A powerful earthquake struck southwestern Japan Tuesday afternoon local time, collapsing part of a shopping mall, toppling a stone wall at the centuries-old Kumamoto Castle, and sending more than 150,000 people to evacuation shelters, the BBC reported.

The quake, which the U.S. Geological Survey (USGS) measured as a magnitude 6.8, hit at 4:27 p.m. local time near Kumamoto, a city of more than 700,000 people located on the island of Kyushu in southern Japan.

Thousands of homes lost power, and roads buckled across the region. The second floor of a shopping center collapsed, trapping shoppers inside, according to the BBC report; some of these people were evacuated and later hospitalized. A brief tsunami warning was issued and lifted within an hour.

The USGS measurement is different from the magnitude 7.1 reported by the Japan Meteorological Agency, "primarily because the agencies are reporting different magnitude types," the USGS reported. While Japan is looking at local magnitude, the USGS measured the moment magnitude, which is derived from the physical size of the fault rupture and gives the "most reliable estimate of earthquake size" for large earthquakes, since local-magnitude scales can lose accuracy once a rupture grows big enough, the USGS reported.

These measurements are helpful, as "different magnitude types capture different characteristics of earthquake source processes," the USGS noted. Local magnitude, for example, reflects how strongly the ground shook nearby, while moment magnitude reflects the total energy released across the fault.

Why this quake is scientifically interesting

Japan sits atop one of the most active plate boundaries on Earth, where the Philippine Sea Plate dives beneath the Eurasia Plate. That process, known as subduction, is responsible for the massive, tsunami-generating earthquakes that periodically strike offshore Japan, and it's been studied intensively for decades.

But Tuesday's earthquake didn't occur at the boundary itself. Instead, the rupture happened within the Eurasia Plate, more than 60 miles (100 kilometers) inland from where the plates meet, Jeffrey Park, a theoretical seismologist at Yale University, told Live Science. Roughly 90% of earthquakes happen at plate boundaries, where the constant grinding of two plates builds up stress until a fault gives way. Quakes that strike farther inside a plate — sometimes called intraplate earthquakes — are rarer and less understood, though scientists suspect that stress transmitted through the plate can reactivate old, dormant faults far from the boundary that produced it.

According to Park, the fault in Tuesday's earthquake moved in a way that suggests the plate tore horizontally as it was twisted by subduction occurring at an angle.

The USGS describes this event as shallow strike-slip faulting: the two sides of the fracture slid past each other horizontally, rather than one side thrusting up and over the other. This faulting style, combined with the shallow depth of just 6 miles (10 kilometers) down, points to the same type of rupture behind Kyushu’s deadly 2016 Kumamoto earthquake sequence.

That inland location is also why the quake didn't generate a damaging tsunami, despite the brief precautionary warning. Tsunamis are produced when a big event ‪—‬ such as an earthquake, volcanic eruption or landslide ‪—‬ displaces water; the force from that displacement then propagates as a wave.

Tuesday's rupture stayed entirely on land, so it never pushed the seafloor up the way offshore quakes do. That's why the tsunami risk stayed low, even with the brief precautionary warning. Still, an inland quake isn't automatically off the hook: if the shaking triggers a landslide that spills into the sea, that alone can generate a tsunami.

The depth mattered just as much as the location. The quake was shallow enough to concentrate its energy near the surface, which Park said explains the structural damage.

"Because it is shallow it will cause more structural damage than a similar-sized event that might occur deeper and offshore," he told Live Science in an email.

Earthquake country

Several earthquakes have already clustered in the area, and numerous aftershocks are expected over the coming days. Japan experiences roughly 1,500 earthquakes annually, making it one of the most seismically active countries on the planet — a byproduct of sitting at the junction of several tectonic plates.

To protect itself, Japan has spent decades — and learned from painful lessons from disasters like the 2011 Tohoku earthquake and tsunami — engineering a response system built for exactly this scenario.

Bullet trains are programmed to halt automatically the instant seismic sensors detect a major earthquake, a safeguard Park pointed to as a defining feature of the country's earthquake readiness. That automatic shutdown extends to other transit and utility systems, part of a broader early-warning network that alerts the public within seconds of a quake's detection, giving people crucial time to take cover before shaking arrives.

Japan's investment in its infrastructure may help to explain why, even after a magnitude 7 event near a city of 700,000, Japan's death toll and damage have historically been far lower than those from comparable quakes elsewhere in the world.

Search-and-rescue efforts are continuing in Kumamoto, with CNN reporting that between 20 and 30 employees remained unaccounted for at the Aeon Mall in Kashima Town, where the building’s second floor had collapsed. Firefighters were also working to reach the site and contain nearby fires.

The two major earthquakes that struck Venezuela just 39 seconds apart on June 24 had slightly different epicenters in north-central Venezuela. The first (M7.2) struck near San Felipe, and the second (M7.5) near Yumare, leaving thousands dead and thousands more injured, according to government officials. But beyond the devastation, the sequence opened a rare scientific opportunity: Researchers think the unusual "earthquake doublet" could offer new insight into how large fault systems interact and how some of the most destructive earthquakes grow.

Large earthquakes are typically followed by smaller aftershocks. But particularly intense events can also alter stress on nearby faults ‪or along the same fault, ‪triggering another major earthquake.

These scenarios are infrequent but not unprecedented. The 2023 sequence in Kahramanmaraş, Turkey, and the 1997 earthquake doublet in Harnai, Pakistan, are two well-known examples.

The Venezuelan sequence also reinforces an emerging consensus among seismologists: that treating faults as isolated structures may underestimate the destructive power of quakes in regions where multiple tectonic faults meet, as they do both in Venezuela and around California's San Andreas Fault system. That's a problem, because many of the seismic hazard models in California do not account for those multi-fault interactions.

A natural laboratory for understanding major earthquakes

The fault system involved in the Venezuelan earthquake ‪—‬ which includes the Boconó, Morón, San Sebastián and El Pilar faults ‪—‬ shares several key characteristics with the San Andreas Fault. Both are right-lateral strike-slip fault systems ‪—‬ in which the crustal blocks slide horizontally past each other ‪—‬ located along the boundary between two tectonic plates: the South American and Caribbean plates in Venezuela, and the Pacific and North American plates in California.

Despite these similarities, researchers caution that the two systems differ in important ways.

"The main difference is that the Venezuelan plate boundary has a much more complex fault architecture," Julián García Mayordomo, a senior scientist in the Geological Hazards and Climate Change Department at the Geological and Mining Institute of Spain, told Live Science.

The difference stems largely from the Maracaibo block, whose interaction with surrounding faults creates a much more intricate plate boundary than California's.

"The other difference is the speed at which the plates move," García Mayordomo pointed out.

In Venezuela, the tectonic plates move past each other at about 0.8 inches (20 millimeters) per year, compared with roughly 1.2 inches (30 millimeters) along the San Andreas Fault. Faster plate motion allows tectonic stress to accumulate more quickly, which influences how often large earthquakes occur over long timescales, but not when the next one will strike.

Along the San Andreas Fault, magnitude 7 or larger earthquakes occur, on average every 100 to 200 years, although the frequency of recurrence varies along the fault. The last major rupture in Southern California was the magnitude 7.9 Fort Tejon earthquake in 1857. In Venezuela, estimated slip rates suggest recurrence intervals of one to two centuries. The region experienced two devastating earthquakes in 1812, part of a multiple-rupture sequence that included events of magnitude 7.5, 7.2 and 6.5, and a 2018 study concluded that the Boconó Fault had already accumulated enough strain to generate another major earthquake.

However, these are statistical averages. The recurrence of large earthquakes is highly irregular and depends on a multitude of factors, many of which we still don't fully understand. So a major event could occur in 100 years ‪—‬ or even tomorrow.

Looking beyond individual faults

This uncertainty is precisely one of the reasons the Venezuelan seismic doublet is generating so much interest among seismologists.

"It is the kind of natural event that can sharpen and test the rupture-interaction concepts that paleoseismic models like ours can only infer indirectly," said Liliane Burkhard, a geologist and geophysicist at the University of Bern and first author of a recent study suggesting that the junction between the San Andreas and San Jacinto faults in Southern California is experiencing some of its highest tectonic stress levels in the past 1,000 years, told Live Science.

"Our Cajon Pass work relied on centuries of paleoseismic reconstructions to infer how stress evolves and whether ruptures can cross between fault systems," Burkhard told Live Science. But that doesn't give geologists real-time data, captured by seismic instruments, showing how different faults interact during quakes, she added.

The Venezuela doublet offers exactly that opportunity. The main lesson for California, Burkhard said, is that interactions between neighboring faults can play an important role in the evolution of large earthquakes.

"Whether it is Cajon Pass where the San Andreas and San Jacinto systems meet or the Boconó-San Sebastián in Venezuela, these are precisely the locations where single-fault hazard models break down because the real behavior depends on how stress is shared and transferred between adjacent structures," she said.

Still, the two systems are quite different. The Venezuelan sequence represents a different type of cascading rupture than the one described in Burkhard's research. At Cajon Pass, the "earthquake gate" concept explores whether a single rupture can jump from one fault system to another during the same earthquake, over tens of seconds of rupture propagation along a continuous fault trace. The Venezuelan doublet, by contrast, "looks like two distinct ruptures on what may be two separate fault structures, triggered in close succession," Burkhard said.

For Burkhard, the Venezuelan earthquake reinforces the need for seismic hazard models to move beyond treating faults as isolated structures and instead represent them as interconnected networks. The challenge is particularly relevant in California, where roughly 300 active faults may interact in ways that traditional hazard models do not capture.

New Zealand has already incorporated this lesson. After the 2016 Kaikōura earthquake ruptured at least 12 faults in a single event, New Zealand revised its National Seismic Hazard Model to include complex multifault ruptures.

García Mayordomo argues that both Venezuela and the United States should incorporate these complex rupture scenarios into seismic hazard assessments and building codes. Earthquakes involving multiple faults can produce longer-lasting shaking that increases structural fatigue and, ultimately, the risk of collapse.

"It's like a boxing match," García Mayordomo said. "Many times the winner isn't the boxer who lands the hardest punch but the one who keeps punching for longer."

Even so, researchers cautioned against drawing sweeping conclusions from a single earthquake.

"Each earthquake gives us one possible scenario," Judith Hubbard, an earthquake scientist and structural geologist at Cornell University told Live Science. "The range of earthquake behaviors is wide."

Thousands of previously undetected tiny earthquakes have revealed the edge of a miniature tectonic plate slamming into Alaska near the Denali Fault.

The microplate could be focusing seismic energy in a straight line in a region under the Alaska Range of mountains, potentially contributing to large earthquakes and the development of small volcanoes in the area.

The Yakutat microplate is an ocean plateau that is thicker than the Pacific oceanic crust surrounding it. Formed by volcanoes tens of millions of years ago, this block of crust is now being pushed under the North American Plate in Alaska in a process called subduction. But because it is thicker and more buoyant than the surrounding oceanic crust, the microplate pushes up the Alaska Range, which includes North America's highest mountain, Mount McKinley (also known as Denali).

"Being able to identify where the Yakutat microplate is in the subsurface has helped us understand the tectonics," said Meghan Miller, the study's first author and a seismologist at the Australian National University.

Part of the plate is still off the coast of Alaska, sticking out like a slipper under a rug. But the precise location of the edge of the plate that has already subducted under the continent has been hard to pinpoint. Miller and her colleagues installed seven new seismometers south of the Denali Fault, which runs through the Alaska Range. This is a tectonically active region, most famous for a 2002 magnitude 7.9 earthquake that was felt as far away as Seattle.

But it wasn't a giant temblor like 2002's that revealed the hidden edge of the Yakutat. Instead, it was unmasked by about 3,000 newly discovered minuscule earthquakes clustered in a clean line running from northwest to southeast for 155 miles (250 kilometers) under the Denali Fault. The "very sharp, linear pattern" also aligns with a series of small volcanic cones and rock-type changes in the deep subsurface, Miller and her colleagues reported in the new study, published June 4 in the journal The Seismic Record.

The researchers suspect that the leading edge of the plate is focusing seismic energy toward the surface. The plate's location also aligns with the initiation point of the 2002 Denali quake, which started on a nearby fault, Miller told Live Science, but exploring that idea further will require computational modeling.

"What we were postulating is that the edge of the Yakutat plate is influencing all these different types of processes," Miller said.

The San Andreas and San Jacinto fault systems are at their highest levels of tectonic stress in 1,000 years, raising the threat of a major, imminent earthquake that could devastate Southern California, a new study finds.

The faults could rupture separately or together, thanks to an "earthquake gate" between them at Cajon Pass, where the San Jacinto fault splits from the main trace of the San Andreas fault. Researchers discovered that Cajon Pass can prevent or facilitate earthquakes moving between the faults, depending on how similar their stress levels are at the time of rupture.

And right now, the San Andreas and San Jacinto faults appear to have comparable, extremely elevated stress levels, potentially spelling trouble for Los Angeles, San Bernardino, Riverside and the Coachella Valley, the team warned.

"Our results show that stress levels on multiple fault segments are now at or above the highest values seen in the past millennium and that the region may be capable of a large through-going rupture involving both fault systems," study first author Liliane Burkhard, a planetary geologist at the University of Bern in Switzerland and at the University of Hawaii at Manoa, said in a statement.

The San Andreas and San Jacinto faults have caused 36 earthquakes with magnitudes of 6.4 or above in the past 1,000 years. Southern California's last "big one" was a magnitude 7.9 event in 1857, when a 205-mile (330 kilometers) segment of the San Andreas fault slipped horizontally between Parkfield and Cajon Pass. That rupture did not propagate through Cajon Pass, but a similar megaquake in 1812 did, suggesting this could happen again in what is now a much more built-up and densely populated environment, according to the study.

Almost 170 years have passed since the 1857 megaquake, raising fears that another huge earthquake could be due to hit soon.

To estimate this risk, Burkhard and her colleagues built a model replicating the last 1,000 years of major earthquake activity along the southern San Andreas and San Jacinto fault systems.

The researchers used observations such as tree-ring records and age data from sediments that have been displaced to reconstruct Southern California's earthquake history. They fed this information into the model, which simulated the accumulation, release and propagation of tectonic stress in the San Andreas and San Jacinto faults.

The results, published June 3 in the Journal of Geophysical Research: Solid Earth, suggest the San Andreas and San Jacinto faults are primed for an Earth-shattering rupture, which may involve the earthquake gate at Cajon Pass opening to unleash more destruction than a single-fault event would on its own.

If a rupture were to occur along the two branches of the San Andreas fault that connect at Cajon Pass, it would be a joint rupture, according to the study. If both branches of the San Andreas fault and the San Jacinto fault were involved, this would constitute a tripartite rupture.

The chance of each event happening and the timing of a potential rupture are unknown, but understanding how much stress is building up inside the system could help planners and policymakers prepare for whatever comes next, Burkhard said.

"What we can say is that the system is critically stressed, and that physics-based models like this one give us a clearer picture of the range of scenarios we should be prepared for," she said. "That information matters for hazard assessment, infrastructure planning, and emergency preparedness."

The researchers say their model could apply to other fault junctions and be used as a tool for hazard assessment globally. "We are using rigorous, quantitative science to better understand the risk facing millions of people," Burkhard said.

Artificial intelligence (AI) has revealed hundreds of previously unknown earthquakes beneath the East Antarctic Ice Sheet, including some in an unexpected place: in the middle of a tectonic plate, far from a plate boundary.

The findings, published May 28 in the journal Science, reveal that Antarctica is more seismically active than previously thought and that new technologies can help to uncover hidden earthquakes in surprising locations.

In the new study, scientists used machine learning, a type of AI, to reanalyze seismic data taken from 49 seismic stations over the past two decades: one dataset from 2001 to 2004, and another from 2012 to 2015. The data revealed over 500 previously unrecognized earthquakes about 60 to 90 miles (100 to 150 kilometers) beneath David Glacier, which stretches nearly 700 miles (1,100 kilometers), bridging East and West Antarctica. This major outlet glacier drains about 4% of the East Antarctic Ice Sheet into the ocean, and its ice has thinned over the past several thousand years.

Earthquakes over 50 miles (80 km) deep are called intermediate-depth earthquakes. This type of earthquake is typically seen only at tectonic plate boundaries ‪—‬ specifically subduction zones, where one tectonic plate dives beneath another.

Yet the study showed that these earthquakes are happening in the middle of the tectonic plate, far from active plate boundaries.

"The earthquakes occur where the cold, rigid crust and upper mantle beneath East Antarctica meets warmer, softer rock beneath West Antarctica, and this contrast creates an abrupt change in tectonic strength," Long Ho, a University of Alabama geologist and first author of the new paper, told Live Science in an email. The detected earthquakes have magnitudes ranging from 1.6 to 3.5. The warm, buoyant material of the upper mantle extends beyond the edges of David Glacier from below, uplifting the edges of the nearby crust and bending them, and this concentrated stress causes the ground to shake, Ho explained.

It was surprising to find so many earthquakes at these depths, far from plate boundaries, Ho said, but similar earthquakes may be occurring in other geographic regions and going unnoticed given their small magnitudes. AI could help to identify those hidden quakes by reanalyzing past seismic data.

"As machine-learning tools continue to improve, they could reveal that deep, continental-interior earthquakes are more common than currently recognized," Ho said. "If so, the role of such events within the plate tectonics framework may need to be re-evaluated."

The results also show that Antarctica is more dynamic than previously thought. "Antarctica was [long] considered to largely lack earthquakes," Richard Alley, a glaciologist at Penn State who was not involved in the new paper, told Live Science in an email. "Now, we know that the apparent lack of earthquakes was really a lack of [tools] to listen to earthquakes." The data from this paper were collected between 2001 and 2004 and are now yielding new results as modern techniques have been developed to analyze the data, Alley said.

The detected earthquakes are not strong enough to threaten the overlying ice sheets or the Antarctic ecosystem, Ho said, so the research team is not concerned about that.

Next, Ho hopes to explore how the enormous weight of the Antarctic Ice Sheet might contribute to the location of earthquakes, and how changes in the ice sheet could affect underlying seismic activity.

It's still puzzling that seismic activity is concentrated at David Glacier rather than spread along the mountains in this region, Alley said, adding that the answer could be linked to the recent history of the ice sheet growing and shrinking, or to a longer history of the ice sheet eroding.

"I worry a lot about the ice sheet," Alley said, "and I hope work like this is continued and expanded, to help us understand the history and improve our understanding of possible futures."

How much do you know about Earth's frozen continent? Test your smarts with our Antarctica quiz!

Egypt's Great Pyramid of Giza, also known as the Great Pyramid of Khufu, has stood for more than 4,600 years, even through powerful earthquakes. Now, new research explains why: The structure is remarkably resilient to vibrations.

The pyramid has lost only about 33 feet (10 meters) of height since its construction during Egypt's Old Kingdom (2649 to 2150 B.C.). That's despite experiencing strong earthquakes over the millennia, including one with an estimated magnitude of 6.8 that struck south of Cairo in the city of Fayum in 1847 and a temblor with a magnitude of 5.9 in 1992 that knocked some of the topmost stones to the ground.

The new study of vibrations throughout the pyramid's structure suggests that certain architectural features, such as a series of chambers known as the pressure-relieving chambers above the chamber where the pharaoh Khufu once rested, dampen seismic movement toward the top of the structure.

"[T]he study highlights the extraordinary practical engineering knowledge of ancient Egyptian builders, who developed highly effective construction practices through centuries of experimentation and refinement," study co-author Asem Salama, a geoscientist at the National Research Institute of Astronomy and Geophysics in Cairo, wrote Live Science in an email.

Salama and his team placed vibration sensors in 37 sites in and around the Great Pyramid and recorded ambient vibrations when no tourists were inside the pyramid. "In heritage conservation, this information can provide important insights into structural stability, hidden vulnerabilities, and long-term preservation strategies while fully respecting the integrity of the monument," Salama explained.

The team found that throughout the pyramid, vibrations were remarkably similar, ranging from about 2.0 to 2.6 hertz. This was quite different from the frequencies on the ground nearby, which were typically around 0.6 hertz. This gap in frequencies means that during earthquakes, the pyramid sits apart from the vibrations traveling through the ground, perhaps contributing to its resilience, the researchers reported Thursday (May 21) in the journal Scientific Reports.

Other features contributing to the pyramid's stability include its massive base, strong limestone foundation and symmetrical geometry, Salama said. The vibrations do increase toward the top of the structure, which is typical in most buildings (imagine a skyscraper built to sway in an earthquake), but this pattern is interrupted by the pressure-relieving chambers that sit about 200 feet (61 m) high inside the pyramid. These chambers lie over the King's Chamber and are thought to have been built to take some of the weight off the pharaoh's final resting place. They also, it turns out, dampen vibrations that otherwise might travel toward the structure's apex.

The researchers plan to take more measurements at the Great Pyramid and hope to use similar methods at other important Egyptian archaeological sites. It's likely that some of the same features of the pyramidal shape help protect the other pyramids at Giza, but each structure is likely unique, Salama said, as ancient Egyptian architects evolved their methods over time.

"Earlier pyramids," he said, "show evidence of experimentation and structural evolution, including changes in slope geometry and internal layouts."

Are you a fan of mummies and hieroglyphs? Find out with our ancient Egypt quiz!

Solar flares often disrupt Earth's upper atmosphere and help power stunning auroras. Now, scientists suggest those same bursts of solar energy might also influence earthquakes.

When a solar flare erupts toward our planet, it can subtly rearrange charged particles in Earth's ionosphere, a region of the upper atmosphere filled with electrically charged gas. In a new study, the researchers suggest that those changes may slightly alter the electrical forces within Earth's crust and affect the stability of faults where earthquakes can occur.

If this connection can be proved, it would link space weather to earthquake risk in a way scientists don't currently account for. But other researchers cautioned that the model used in the study, published Feb. 3 in the International Journal of Plasma Environmental Science and Technology, is overly simplified, and that real-world geology may dampen the effect to nearly nothing.

A planet-sized electrical circuit

Our planet is buzzing with naturally generated electricity. In particular, highly stressed cracks in Earth's crust contain pockets of water that is so hot and pressurized it is neither liquid nor gas. This supercritical fluid is teeming with charged ions, meaning the cracks behave like a capacitor, storing electrical energy.

These cracks in the crust, or faults, are also key regions that trigger earthquakes, because they mark where tectonic plates collide and move, building up mechanical energy that can result in quakes.

In the new study, the researchers created a model that treated Earth's crust and the ionosphere — a charged layer 250 miles (402 kilometers) above Earth — as two ends of a giant, leaky battery.

They then connected the crust "capacitor" to the ionosphere with an electrical field.

The scientists used their to model predict that when a solar flare's electrically charged particles hit Earth, they shift electrons in the ionosphere downward, which concentrates them at lower altitudes, forming a layer of negative charge. This charge, in turn, increases the electrostatic force acting upon the charges in Earth's crust, producing pressure changes, the model showed. The researchers argue that these pressure changes are comparable to other forces that affect fault stability, like gravity or tides.

Essentially, the increase in electrostatic force in the crust translates to more pressure exertion on the surrounding crust, nudging a fault to move and result in an earthquake.

Hard to test

The researchers suggest that the 2024 Noto Peninsula earthquake in Japan supports their model's findings, as the quake overlapped with strong solar flare activity. However, validating a crust-to-ionosphere connection is difficult in practice.

For one thing, the U.S. Geological Survey has long emphasized that earthquakes do not follow the sun's 11-year solar cycle in any clear, repeating way.

There's also a coincidence problem. Solar flares and earthquakes are rather common, so by chance there will be some overlap between the two types of event, even if they don't necessarily influence each other.

Other researchers noted that the study's model does not reflect the full complexities of Earth's crust.

"The proposed model is greatly simplified," said Victor Novikov, a geophysicist at the Russian Academy of Sciences, who was not involved in the study. He added that the researchers did not fully account for many rock layers' resistance to conducting electricity, which could suppress the electric field before it contributes to a quake. "Observational results do not support the proposed idea," Novikov told Live Science in an email.

Despite this, researchers continue to search for a link between space weather and plate tectonics, however subtle it may be.

For now, the study is best viewed as a proposed pathway that could be tested with better observations and deeper analysis, the researchers noted.

Whether the sun can reliably jostle Earth's faults remains an open question and a reminder of a basic scientific rule: Correlation does not equal causation.

What's inside Earth quiz: Test your knowledge of our planet's hidden layers

The 2011 Tohoku earthquake that triggered a devastating tsunami in eastern Japan was worsened by a thick layer of slippery clay, new research finds.

The clay layer, which was up to 98 feet (30 meters) thick on the ocean floor, created a weak spot that enabled the magnitude 9.1 quake's movement to travel all the way to the seafloor. That motion thrust the seafloor upward by 164 to 230 feet (50 to 70 m) over about 310 miles (500 kilometers). And the motion of the seafloor thrusting into the overlying ocean is what created the tsunami wave that inundated 217 square miles (561 square kilometers) of Japan.

"It's low-friction, so that clay is weak," said Ron Hackney, a geophysicist at the Australia National University and the director of the Australian and New Zealand International Scientific Drilling Consortium. "It can slip very easily."

The side-to-side breakage of the fault was about half of what researchers would have expected, Hackney told Live Science, which concentrated the upward motion into a smaller area, probably intensifying the resulting tsunami. The findings explain why the tsunami was larger and more concentrated than expected, he said, and these kinds of detailed studies can help provide better warnings for future quakes.

"We can be a bit more prepared in terms of informing people of what to expect and how to respond when an earthquake does happen," he said.

The 2011 quake happened along a subduction zone, where the Pacific Plate slides under Japan. In 2024, Hackney and other researchers aboard the research vessel Chikyu drilled directly into the fault that caused the quake. After drilling 23,000 feet (7,000 m) below the ocean surface and another 3,300 feet (1,000 m) below the seafloor, they pulled up cores of sediments from within the fault and from the Pacific Plate.

They found that the Pacific Plate is covered with a thick, goopy layer of clay that has been accumulating slowly for around 130 million years. This layer compresses as the Pacific Plate pushes under Japan, also squeezing the continental rocks above. The result is a mechanical weak point, almost like a perforation on a piece of notebook paper, where the rock is prone to breaking.

The researchers published their findings December 2025 in the journal Science.

Similar clay layers may or may not exist at other subduction zones, Hackney said. There is some evidence that they might be present near Sumatra, Indonesia, the site of the magnitude 9.1 earthquake that caused a devastating tsunami on Dec. 26, 2004. But less is known about the materials coming into the fault zone at places like the Kamchatka Peninsula, where large quakes also occur, he said.

Hackney and his colleagues are working to find links between topography and rock density and ultimate earthquake movement. Earth scientists are getting increasingly good at predicting how large a quake will be and where the shaking will be felt once a quake happens, enabling early warning systems that can alert people to incoming shaking seconds to minutes in advance. Tsunami warnings have an even longer lead time, so perfecting the understanding of how the seafloor moves to better predict where a tsunami will go could save even more lives.

Vanishing lakes in southern Tibet may have triggered earthquakes in the region by "awakening" long-dormant faults in Earth's crust, researchers say. The finding adds to evidence of an unexpectedly strong link between our planet's climate and the geological activity deep beneath our feet.

About 115,000 years ago, southern Tibet was home to enormous lakes, some more than 125 miles (200 kilometers) long. Today, those lakes are much smaller. They include Nam Co Lake (also called Namtso Lake or Lake Nam), which is just 45 miles (75 km) long.

A team of geologists led by Chunrui Li, a researcher at the Chinese Academy of Geological Sciences in Beijing, suspected that water loss from the lakes might have had knock-on effects for the local geology. This is partly because large lakes weigh down Earth's crust. When they begin to dry up, that weight is lost and the crust slowly rises again, in much the same way that a heavily laden ship rises in the water as its cargo is removed.

A second key point is that southern Tibet is geologically active because of the ongoing collision between India and Eurasia, which began about 50 million years ago. Strain has built up in Earth's crust beneath southern Tibet, leaving ancient cracks — or faults — in the crust ready to rupture. The geologists reasoned that the slow rise of the crust caused by the shrinking lakes might have triggered such ruptures and generated earthquakes.

The researchers think that this has happened. They analyzed the local geology, mapping the ancient lake shorelines to work out how much water the lakes have lost. They then used computer models to predict how much the crust should have risen in response, revealing that this should have reactivated nearby faults.

The study was published Jan. 17 in the journal Geophysical Research Letters.

Their analysis suggests that water loss from Nam Co Lake between 115,000 and 30,000 years ago led to a total of 50 feet (15 meters) of movement on a nearby fault. The lakes 60 miles (100 km) to the south of Nam Co Lake have lost even more water over the same time period. There, there may have been 230 feet (70 m) of movement on nearby faults.

These calculations suggest that the faults in the region have experienced between 0.008 and 0.06 inches (0.2 and 1.6 millimeters) of movement per year, on average. For comparison, the San Andreas Fault running through California records far more movement: about 0.8 inches (20 mm) each year, on average. But there, the movement is driven largely by processes occurring deep belowground. The new study is evidence that substantial movement on faults can also be affected by processes happening aboveground.

"Surface processes can exert a surprisingly strong influence on the solid Earth," Matthew Fox, an associate professor of geology at University College London who was not involved in the study, told Live Science in an email. "Geologists are increasingly aware that to fully understand the evolution of a landscape or tectonic region, we need to consider this coupling between surface and deep Earth processes."

This doesn't mean earthquakes will occur whenever and wherever lakes are drying up, said Sean Gallen, an associate professor of geology at Colorado State University who was not involved in the research. Such earthquakes will occur only where the lakes sit above crust that has accumulated strain because of tectonic activity. "Tectonics is always the driver," he told Live Science. "Changes in water load just alter how the built-up tectonic strain is released over time."

Strain can also be released by other surface processes, Philippe Steer, an assistant professor of geosciences at the University of Rennes in France, told Live Science. Severe storms may trigger sudden and rapid erosion, removing heavy rock from some parts of the crust and allowing it to rise. Quarries where large amounts of rock are removed from the ground have a similar effect, said Steer, who was not involved in the study.

But perhaps the most significant "unloading" events in the recent geological past relate to the last glacial maximum. At that time, about 20,000 years ago, large chunks of North America and Eurasia were weighed down by enormous ice sheets, which were several miles thick in places. Those ice sheets had largely vanished by about 10,000 years ago. But because they were so heavy, the crust beneath where they once lay is still rebounding today.

Some researchers think this may help to explain a long-standing geological mystery. Almost all powerful earthquakes occur along major faults, like the San Andreas, that are found at the boundaries between Earth's tectonic plates. But occasionally, powerful earthquakes can occur in the middle of a tectonic plate, thousands of miles from one of these boundaries. For instance, in 1811 and 1812, there were three earthquakes of magnitude 7 or 8 along the Mississippi River valley in the central United States.

One idea is that strain slowly accumulated on ancient faults in the Mississippi River valley because of geological activity thousands of miles away, along the edges of the North American tectonic plate. Then, when the ice sheets melted and Earth's crust began to rise, that strain was released in the form of powerful earthquakes.

"While climate change does not 'cause' tectonics, it can modulate the stress conditions in the crust," Fox said. "That's something we need to factor into future hazard assessments."

What's inside Earth quiz: Test your knowledge of our planet's hidden layers

Earthquakes that jiggle Earth's middle layer may be more widespread than scientists thought.

A new map of these mysterious deep earthquakes shows that they occur all around the world and that they may have a variety of causes. That's interesting, said study senior author Simon Klemperer, a geophysicist at Stanford University, because mantle earthquakes were once thought to be impossible, or at least rare. These quakes originate below a border known as the Mohorovičić discontinuity, or "Moho" — the line between the brittle crust and the hotter, gooier mantle.

"We believe this firmly demonstrates that there are earthquakes below the Moho in very many regions of the world," Klemperer told Live Science. "It's not just special places. It's possibly ubiquitous."

Most earthquakes start in the crust, which is like a layer of toasted sugar over the softer, more deformable cream filling that is the mantle. This brittle crust can't deform, so it cracks under stress, causing the ground to shift and shake. For a long time, geoscientists thought this couldn't happen in the mantle, which has a taffy-like texture and tends to ooze instead of snap. But over the years, seismologists studying earthquakes have turned up evidence of quakes with deep origin points more than 22 miles (35 kilometers) down, which would put them below the Moho.

But pinpointing these quakes is difficult, especially when they are not large. In general, these earthquakes are so deep that they can't be felt at the surface, regardless of their size. The Moho's depth also varies from place to place, so it's possible that some very deep quakes are still in the crust.

Traditional methods of pinpointing mantle quakes required a specific understanding of how thick the crust might be in that particular location. But Klemperer and his co-author, Stanford doctoral student Shiqi Wang, developed a method that uses specific types of earthquake shear waves that tend to get trapped in either the crust or the mantle. The pattern of these waves in each individual earthquake can determine whether it's likely to have started above or below the Moho.

First, they tested the method in Tibet in 2021. Now, in a new paper published Feb. 5 in the journal Science, they have taken the research global. The researchers excluded subduction zones, which often have deep earthquakes because rocks from the crust get pushed into the mantle in these regions. Instead, the team focused on the more elusive phenomenon of mantle earthquakes under the continents.

They found mantle quakes all over the place. A dense band of them stretches from the Alps to the Himalayas, probably related to the mountain-building continental collisions in these regions. Another cluster occurs in East Africa, where the continental crust is rifting apart. There are also mantle earthquakes under the western United States and in Baffin Bay, Canada, the researchers found.

Some of the cluster locations were surprising. "There were some regions where nobody had found these before, like in the Bering Sea," Vera Schulte-Pelkum, a geologist at the University of Colorado Boulder who was not involved in the study, told Live Science. "I'd love to get an interactive version of these and zoom around."

The global overview should allow other scientists to do more specific studies on individual mantle quakes, Klemperer said, and perhaps better pinpoint their depths and the mechanisms driving the earthquakes.

"It's tremendously exciting that we have this tool that can now be applied on a very routine basis," he said.

What's inside Earth quiz: Test your knowledge of our planet's hidden layers

Deep-sea landslides in the Pacific Northwest's Cascadia subduction zone hold a record of earthquakes dating back 7,500 years, and similar markers may be found in other tectonic plate boundaries worldwide, new research shows.

Subduction zones are places where an oceanic tectonic plate dives beneath a continental plate, which can cause large and damaging earthquakes like the 2011 Tohoku magnitude 9.1 earthquake in Japan that triggered a devastating tsunami. The Cascadia subduction zone — which extends from northern California to Vancouver Island, British Columbia — is capable of quakes of at least magnitude 9.0, according to the Pacific Northwest Seismic Network.

Exactly how often such enormous quakes hit is an open question, however. To tease out the history of Cascadia quakes, researchers turn to geological evidence such as sudden land-level changes and turbidites, which are undersea sediment flows that occur off the coast during large quakes.

But turbidites in submarine canyons near the shore can also be caused by storms, currents and regular landslides that have nothing to do with earthquakes. In the new study, published Wednesday (Jan. 14) in the journal Science Advances, U.S. Geological Survey research geologist Jenna Hill and her colleagues decided to go deeper. They collaborated with the Monterey Bay Aquarium Research Institute to study the continental slope — the steep dropoff from the North American continent to the plains of the deep sea — in southern Cascadia.

Focusing on an area off the coast of Crescent City, California, the researchers used autonomous and remotely operated vehicles to get detailed views of the slope and sediment deposits. They also used sediment cores from the region to radiocarbon-date the turbidite deposits and compare their timing to the dates of known ancient Cascadia quakes.

The researchers found evidence of at least 10 events in the past 7,500 years, which enabled them to link historical quakes, landslides and resulting turbidites.

"We are able to clarify how and where the turbidites are generated," Hill told Live Science. "So we know they're coming from landslides that we know are triggered by earthquakes."

It's not clear how large a quake has to be to trigger deep-sea turbidites, Hill said, but it probably has to be large enough to cause damage. She and her colleagues also saw signs of seafloor shaking corresponding with the earthquake turbidites, which could additionally raise the risk of tsunamis from this type of quake.

Turbidites found in submarine canyons closer to the coast of the Pacific Northwest have already been used to link earthquakes in Cascadia to quakes on the nearby San Andreas Fault. Turbidites on the continental slope may be even more reliable markers of quakes because they're less influenced by coastal processes such as tides or rainfall, Hill said.

"We think they're happening most everywhere along subduction zones," she said, "so we should be able to find these landslide deposits and marine turbidites globally in places where we have never looked for them before."

A fragment of a long-lost tectonic plate is sliding under the North American continent in the southern part of the Cascadia subduction zone, scientists have discovered. This leftover plate fragment could pose a new earthquake risk to the region.

New research, published Thursday (Jan. 15) in the journal Science, revealed that the Pioneer Fragment — a leftover bit of an oceanic plate that disappeared under the North American Plate some 30 million years ago — is now stuck to the floor of the Pacific Ocean and is moving northwest along with that plate.

This is happening at a spot called the Mendocino triple junction, where California's famous San Andreas Fault abuts the Cascadia subduction zone. Along the San Andreas, the North American and Pacific plates move alongside one another. At Cascadia, which extends from Cape Mendocino, California, to Vancouver Island, British Columbia, the Juan de Fuca and Gorda oceanic plates dive below North America. That tectonic motion is capable of setting off earthquakes of magnitude 9 and above, according to the Pacific Northwest Seismic Network.

Some evidence suggests that earthquakes in the Cascadia subduction zone might trigger earthquakes along the San Andreas, a possibility that would widen the danger from the Cascadia fault.

While the new findings don't make the risk clear, said study first author David Shelly, a geophysicist at the U.S. Geological Survey in Golden, Colorado, they are a step toward understanding this relationship.

The Pioneer Fragment "does increase the area of contact between what’s effectively the Pacific Plate and the subduction zone," Shelly told Live Science.

Shelly and his colleagues probed the Mendocino triple junction using tiny low-frequency earthquakes and tremors — a kind of seismic shiver that originates deep in the crust and can't be felt without sensitive seismometers. "They’re teeny-tiny events but they often occur on the biggest faults," Shelly said.

By analyzing these events, the researchers determined the direction of subtle plate motions. At Mendocino, the Pacific Plate is sliding northwest against the North American Plate, bumping against the Gorda Plate as it pushes under North America. It's a complex situation, and there are competing explanations for exactly where all the pieces are and where the faultlines run.

Shelly and his colleagues found that the situation is even more complex, because a surprise piece of long-gone Farallon Plate still has an influence on the triple junction. This ancient tectonic plate started subducting under North America 200 million years ago, during the breakup of the supercontinent Pangaea. The Juan de Fuca is one remnant of the Farallon. But now, the researchers found that another remnant got stuck to the Pacific plate. This remnant, the Pioneer Fragment, isn't subducting but rather moving sidelong against the continent.

Meanwhile, bits of the Gorda Plate that got scraped off onto the North American Plate as the two ground together have now seemingly been passed back to the Gorda like a "tectonic hot potato" and may be diving back below North America, Shelly said.

This bit of geological messiness may explain why one of the largest triple junction quakes, the 1992 Cape Mendocino earthquake, had a shallower origin than scientists expected. Because of the extra bits and pieces, "the fault may not be following the oceanic crust itself. It may be shallower than that," Shelly said.

Beyond increasing the surface area of the Pacific Plate that interacts with Cascadia, the Pioneer Fragment might have the potential to cause earthquakes itself. Between the fragment and the North American Plate is a nearly horizontal fault, like the icing in a layer cake.

"We don’t know whether that fault can generate large earthquakes, but it is a fault that isn’t currently in the hazard models," Shelly said. "So it’s something we need to consider in the future."

Predicting earthquakes before they happen is currently impossible, but scientists are edging closer and closer with new and innovative ways to monitor movements in Earth's crust. In this excerpt from "When Worlds Quake: The Quest to Understand the Interior of Earth and Beyond" (Princeton University Press, 2026), author Hrvoje Tkalčić, the head of geophysics at the Australian National University, delves into the reasons why earthquake prediction is so tricky, looking at the "Parkfield Experiment," where scientists waited nearly 20 years for an earthquake on the San Andreas Fault to strike.

You can often read rude and even vulgar comments under online newspaper articles about the purpose of the seismological profession when people in their post-earthquake trauma realize that seismologists don't forecast like meteorologists do, such as forecast hail or tornadoes with high accuracy.

An approximate answer to these comments could be given with the following targeted question: "We still can't beat malignant diseases, but should we stop researching because of that?"

We are used to discussions about earthquake causes after every event, particularly in the places where the world's earthquakes occur. There are discussions about their frequency, and quite often, there are those who claim they could recognize the coming earthquake in something else. Whether it's a full moon, a planetary conjunction, too much rainfall, bone pain, overexploitation of the planet's resources or greed, people tend to believe that earthquakes have simpler explanations than physical forces in the interior of the Earth and, of course, that they can be predicted.

Let's travel to California in the 1970s and 80s, to a small, picturesque town of only 18 inhabitants — Parkfield — located between San Francisco and Los Angeles, near the central part of the San Andreas Fault. You’re probably wondering why. Well, this small town is known to the seismological world for its turbulent geological history. Namely, on average, significant earthquakes have occurred in Parkfield every 22 years since the middle of the 18th century.

But it was fascinating that the recorded seismograms for the earthquakes of 1922, 1934 and 1966 were almost identical, one wiggly seismogram line to the other. In addition, the 1934 and 1966 earthquakes had foreshocks — about 17 minutes before the main shock — whose seismograms also looked very similar.

You wonder how such a thing is even possible. Such similarity of seismograms is possible only if the same fault surface is always activated and recorded with the same instrument at sufficiently long waves. Of course, the shorter the waves, the greater the differences. In other words, you have a source — an earthquake and a receiver — a seismometer at fixed locations, and waves propagating between them through the same material. So, you have a perfect natural laboratory and an experiment set up in it. You just have to wait long enough.

Scientists, therefore, had good maps in hand to investigate the mechanisms of earthquakes that recur from time to time on an active, well-monitored fault. Since the mid-1980s, they have installed a whole arsenal of instruments near Parkfield and along the fault: powerful seismographs, then strainmeters, which measure rock deformation at a depth of 650 feet (~200 meters) along the fault, magnetometers for measuring the intensity of the magnetic field, creepmeters, which measure displacements on the surface along the fault, and other scientific "weaponry." They forecasted with 90 to 95% confidence that the next earthquake there would occur between 1985 and 1993. Some of the key questions were:

1. How is stress distributed in space and time on the fault due to the action of tectonic forces before and after the earthquake?

2. Do earthquakes repeat at an average time interval, or is each earthquake unique, a story in itself?

3. How do the structure of faults and surrounding rocks affect the nucleation of smaller earthquakes and the possibility of larger ones and their distribution in time and space?

They wondered what the deformation we measure on the surface could tell us about the stress distribution on the fault, and they hoped for a positive result — confirmation of the predictions for earthquake occurrences between 1985 and 1993. They waited and waited. In those years, I worked once a week with colleagues at the U.S. Geological Survey California office in Menlo Park, in the northwestern part of Silicon Valley, where I was able to observe some scientists involved in the experiment.

Eventually, a magnitude 6.0 earthquake did happen in Parkfield, but not until 2004. We greeted the most watched and studied earthquake in human history with a huge question mark above our heads; it occurred 11 years after its forecasted time. Devastating. That’s why the "Parkfield Experiment" left a bitter taste of disappointment in the mouth. But, as they say, only those who dare to fail eventually succeed. Research continued.

Why is earthquake prediction so tricky? Each fault is different — some of them we know about, but many we don't — earthquake catalogs don't go back far enough, and, after all, underground architecture is entirely invisible to us.

We do not know how deep the fault reaches, whether it is a flat or curved surface, whether its surface is smooth or rough, whether and where it touches other faults, the chemical composition of the rocks on one and the other side of the fault, or their physical properties, for example, strength and porosity. We do not know precisely how the deformation we observe on the surface of the Earth can be related to the deformation and stress in the depth of the fault. We also do not know many other factors. A forecast can be made, but by its very nature, it must be probabilistic and taken with a grain of salt. So, how do we proceed?

Not everything is so negative. The first good news is that seismic hazard maps exist in most countries. They are well made, but of course, they must be constantly updated. The other good news is that, based on fundamental knowledge of physics and the propagation of seismic waves through the interior and across the surface of the Earth, we can predict how the ground and some buildings will behave during an earthquake, and that is already a major benefit.

This is possible because of basic science and seismological research on the nature of the subsurface, in a similar way that radiologists can illuminate the inside of the human body. Ironically, earthquakes help us because they serve as a source of waves illuminating the Earth's interior. It is possible to predict infrastructure behavior during earthquakes due to the development of engineering, construction, computer science and numerical methods. Either way, those hazard maps serve as input for engineers, builders and insurance companies.

In the end, the most positive thing is that modern studies involving laboratory models and artificial intelligence are being carried out across the world, aimed in the direction that one day we will be able to predict earthquakes. Certainly not without major investment in science and technology, which will need to continue to develop. This might even take us to the point where we will have to place thousands or millions of microsensors on every fault in the Earth's interior and then monitor the strain in real time.

In a way, we will have a "crystal ball" — an insight into the dynamics and future behavior of faults. In fact, we are already doing it today, but we have only scratched the surface of the Earth with the help of satellites. InSAR, LIDAR and GPS are just some of the networks and methods that give us an insight into where the Earth's crust is most stressed from surface deformations.

The stress or tension build-up mechanism on a fault is still under investigation. It is most likely that the hot rocks of the Earth's continental crust beneath approximately 9.3 miles (15 kilometers) of depth are ductile, and this rock mass "flows" at a higher speed than on the surface, but without earthquakes, and the upper part of the crust therefore bends and the stress along the fault surface increases. However, how this stress is distributed in space is not yet known.

Furthermore, laboratory experiments at high pressures and temperatures give us insight into how hard rocks are and how strain and stress are related. The chemical and physical structure of the soil is examined by drilling around the fault. Old tree trunks are explored, and excavations are made to detect historical earthquakes on rock samples.

Investments are made in studying the deeper interior of the Earth and the mechanism of earthquakes using seismic waves and tomography methods. Investments are also made in mathematical geophysics, as well as in machine learning and improved techniques for processing enormous amounts of digital data. Investments are also made in alarm systems based on the detection of P waves. Even a few seconds of warning before the arrival of S waves can be crucial to saving people and infrastructure. Likewise, investments are being made in modern construction resistant to earthquakes.

But the conclusion is that, unless you want to move to stable parts of the continents, somewhere in Siberia, to the northernmost, permanently frozen parts of Canada, or the remote regions of the Australian Outback seldom struck by earthquakes, we need to learn to live with earthquakes.

Adapted from When Worlds Quake: The Quest to Understand the Interior of Earth and Beyond. Copyright © 2026 by Hrvoje Tkalčić. Reprinted by permission of Princeton University Press.

Glacial earthquakes are a special type of earthquake generated in cold, icy regions. First discovered in the northern hemisphere more than 20 years ago, these quakes occur when huge chunks of ice fall from glaciers into the sea.

Until now, only a very few have been found in the Antarctic. In a new study published in Geophysical Research Letters, I present evidence for hundreds of these quakes in Antarctica between 2010 and 2023, mostly at the ocean end of the Thwaites Glacier — the so-called Doomsday Glacier that could send sea levels rising rapidly if it were to collapse.

A recent discovery

A glacial earthquake is created when tall, thin icebergs fall off the end of a glacier into the ocean.

When these icebergs capsize, they clash violently with the “mother” glacier. The clash generates strong mechanical ground vibrations, or seismic waves, that propagate thousands of kilometres from the origin.

What makes glacial earthquakes unique is that they do not generate any high-frequency seismic waves. These waves play a vital role in the detection and location of typical seismic sources, such as earthquakes, volcanoes and nuclear explosions.

Due to this difference, glacial earthquakes were only discovered relatively recently, despite other seismic sources having been documented routinely for several decades.

Varying with the seasons

Most glacial earthquakes detected so far have been located near the ends of glaciers in Greenland, the largest ice cap in the Northern Hemisphere.

The Greenland glacial earthquakes are relatively large in magnitude. The largest ones are similar in size to those caused by nuclear tests conducted by North Korea in the past two decades. As such, they have been detected by a high-quality, continuously operating seismic monitoring network worldwide.

The Greenland events vary with the seasons, occurring more often in late summer. They have also become more common in recent decades. The signs may be associated with a faster rate of global warming in the polar regions.

Elusive evidence

Although Antarctica is the largest ice sheet on Earth, direct evidence of glacial earthquakes caused by capsizing icebergs there has been elusive. Most previous attempts to detect Antarctic glacial earthquakes used the worldwide network of seismic detectors.

However, if Antarctic glacial earthquakes are of much lower magnitude than those in Greenland, the global network may not detect them.

In my new study, I used seismic stations in Antarctica itself to look for signs of these quakes. My search turned up more than 360 glacier seismic events, most of which are not yet included in any earthquake catalogue.

The events I detected were in two clusters, near Thwaites and Pine Island glaciers. These glaciers have been the largest sources of sea-level rise from Antarctica.

Earthquakes at the Doomsday Glacier

Thwaites Glacier is sometimes known as the Doomsday Glacier. If it were to collapse completely it would raise global sea levels by 3 meters (10 feet), and it also has the potential to fall apart rapidly.

About two-thirds of the events I detected — 245 out of 362 — were located near the marine end of Thwaites. Most of these events are likely glacial earthquakes due to capsizing icebergs.

The strongest driver of such events does not appear to be the annual oscillation of warm air temperatures that drives the seasonal behavior of Greenland glacier earthquakes.

Instead, the most prolific period of glacial earthquakes at Thwaites, between 2018 and 2020, coincides with a period of accelerated flow of the glacier's ice tongue towards the sea. The ice-tongue speed-up period was independently confirmed by satellite observations.

This speed-up could have been caused by ocean conditions, the effect of which is not yet well understood.

The findings suggest the short-term scale impact of ocean states on the stability of marine-terminating glaciers. This is worth further exploration to assess the potential contribution of the glacier to future sea-level rise.

The second largest cluster of detections occurred near the Pine Island Glacier. However, these were consistently located 60–80 kilometers [37 to 50 miles] from the waterfront, so they are not likely to have been caused by capsizing icebergs.

These events remain puzzling and require follow-up research.

What's next for Antarctic glacial earthquake research

The detection of glacial earthquakes associated with iceberg calving at Thwaites Glacier could help answer several important research questions. These include a fundamental question about the potential instability of the Thwaites Glacier due to the interaction of the ocean, ice and solid ground near where it meets the sea.

Better understanding may hold the key to resolving the current large uncertainty in the projected sea-level rise over the next couple of centuries.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Cracks deep in Earth's crust can stick themselves back together within hours after certain earthquakes, new research suggests.

Specifically, these cracks can heal speedily after what geologists call slow slip events. This is when the deformation- and stress-induced movement between two sides of a fault occurs over days, weeks or months, rather than over seconds or, for the largest earthquakes, minutes.

Slow slip events are "silent" earthquakes in which the slip happens much more slowly and doesn't radiate the strong waves that can make regular earthquakes dangerous, said study lead author Amanda Thomas, a professor of geophysics at the University of California, Davis.

"Slow slip events and regular earthquakes can occur on the same major fault systems, but they typically happen at different depths and under different physical conditions," Thomas told Live Science in an email. "What determines whether the fault slips slowly or suddenly is the fault frictional behavior and the effective stress on the fault."

Thomas and her colleagues studied slow slip events deep in the Cascadia subduction zone, a "megafault" where the Juan de Fuca Plate slides under the North American Plate. Cascadia experiences lots of these slow slip events and has an exceptional seismic monitoring network, making it one of the best places in the world to study this phenomenon, Thomas said.

The megafault is capable of unleashing magnitude 8 and 9 earthquakes. "In subduction zones like Cascadia, large earthquakes occur in shallow, colder rocks, while slow slip happens deeper where temperatures and pressures are much higher and fluids are abundant," Thomas explained.

Cascadia's slow slip events are unusual in that they sometimes rupture the same zone repeatedly during a single event. Within just a few hours, one area of the fault can break multiple times, which suggests both that stress is reloaded quickly and that a "healing" process occurs between ruptures. "That repeated re-activation is one of the puzzles our study set out to explain," Thomas said.

The results were published Nov. 19 in the journal Science Advances.

Because the depths of Cascadia are inaccessible, the researchers re-created in the lab the conditions thought to exist deep within the subduction zone. They loaded a silver capsule with powdered quartz and a trickle of water to mimic rocks and deep fluids, respectively. The team then welded the capsule shut, heated it to about 930 degrees Fahrenheit (500 degrees Celsius), and put it under a pressure 10,000 times higher than atmospheric pressure for up to 24 hours.

Next, the researchers used electron microscopy to glean what had happened to the quartz powder. They found that the mineral grains had been welded together, even in samples that had been "cooked" for only a few hours.

"Fault healing depends strongly on temperature, pressure, and the presence of fluids," Thomas said. "In our experiments, these conditions produced measurable strengthening within hours."

Regular earthquakes typically occur in shallower regions of the crust, so it takes much longer — years to decades — for fractures to heal. "Our results suggest the same basic process can operate across the crust, but the timescales change depending on the environment," Thomas said.

The other part of the puzzle addressed in the study is how stress is reloaded so rapidly during slow slip events in Cascadia. The subduction zone experiences low-frequency earthquakes, which are small seismic events triggered in bursts when the same area ruptures again and again. These bursts overlap with ocean tide cycles, suggesting tidal changes can cause a fault to re-rupture just hours after it has repaired itself.

"In Cascadia, rapid healing means that parts of the deep fault can re-strengthen quickly enough to be re-activated multiple times during one slow slip cycle," Thomas said. "That affects how we model slow slip and how we interpret the signals we use to monitor the deep fault."

Fault healing is also an important consideration in shallower regions, including those known to cause major earthquakes. Repair processes should be included in the next generation of models, as they could improve our understanding of earthquake risks, Thomas said.

Scientists are deliberately triggering earthquakes from a tunnel deep beneath the Alps. Although it may sound like something out of a James Bond movie, the goal isn't turmoil and destruction. Rather, researchers with the Fault Activation and Earthquake Rupture (FEAR) project are looking for ways to determine the danger of an earthquake before it strikes.

Despite an increasing amount of monitoring on fault lines worldwide, researchers still don't understand the immediate triggers of earthquakes. Nor do they know why some ruptures happen on short segments of fault lines while others run for many miles, causing greater destruction. Right now, geoscientists are limited to studying these events only after they happen, Domenico Giardini, professor of seismology and geodynamics at ETH Zürich, told Live Science.

"What are the signs that nature is telling us?" Giardini said. "Invariably, they become clear after the quake, not before, so we are trying to understand much better how to see the signs."

That means they must trigger real earthquakes in controlled conditions with thousands of monitors right on a fault — not an easy prospect. But Giardini and his colleagues are taking advantage of the massive power of the Alps themselves. These mountains, on the border of Switzerland and Italy, are deeply faulted; the zigzagging networks of cracks beneath them are the legacy of millions of years of tectonics. Just the compressional force of the towering mountains above is enough to fracture the rocks 0.6 to 1.2 miles (1 to 2 kilometers) below the surface.

The rocks on the sides of these faults do occasionally slip, giving off mostly small quakes. Using a preexisting tunnel that was once used in the construction of a railway project, the FEAR project is getting up close and personal with one of these faults and pumping water into them to trigger it to release earthquakes on a convenient time schedule.

"They would have taken place sooner or later in the history of the Alps, but we make sure they happen next week," Giardini said.

The process is similar to what happens when oil and gas companies inject wastewater from wells into faulted areas in places like Oklahoma and Texas. This water lubricates the faults, thus reducing the friction required for them to rupture.

The difference is that Giardini and his team have a dense network of seismometers and accelerometers right on the fault, so they can measure exactly how it moves in response to this decrease in friction. The team has already triggered hundreds of thousands of quakes up to magnitude zero. (Because earthquakes are measured on a nonlinear, logarithmic scale, it's possible to have very small quakes with a magnitude of zero or even with negative magnitudes.)

Next week, the researchers will begin injecting hot water into the fault to see how temperature affects the evolution of an earthquake. And in March, Giardini said, they'll start triggering earthquakes up to magnitude 1.

The idea is that if they can figure out what parameters trigger a quake of a certain size — if they can, in essence, trigger a quake of whatever size they desire — they'll eventually be able to measure a dangerous fault in the real world before it breaks and calculate the kinds of stresses needed to trigger a quake of a certain size on that fault.

"A couple years ago [in February 2023], there was a very large quake on the border between Syria and Turkey," Giardini said. "We know that fault will continue toward the south and toward the north. We want to try to understand, is the next quake going to be a 7 or an 8 or 8.5?"

Already, he said, certain parameters, like the amount of strain in the rocks outside the fault, are proving to be important. The researchers are also starting to understand more about how quakes jump from one fault to a neighboring fault.

"We are seeing examples that we produce ourselves underground that look very much like what happens in nature," Giardini said.

A newly discovered way to monitor magma movements beneath Mount Etna could help scientists forecast when it might erupt.

Mount Etna, located on the Italian island of Sicily, is Europe's largest active volcano. Humans have documented its activity for the past 2,700 years, but the volcano's eruptive history stretches as far back as 500,000 years.

Etna's most recent eruption, in June 2025, ejected a giant, 4-mile-high (6.5 kilometers) cloud of ash and triggered an avalanche of hot lava blocks and other debris. The eruption was expected, so officials were able to issue warnings on the morning of the event, but predictions don't always hit the nail on the head.

The novel method could make it easier to predict Mount Etna's eruptions. In a new study, researchers at Italy's National Institute of Geophysics and Volcanology (INGV) analyzed a parameter called the b value, which describes the ratio of low-magnitude to high-magnitude earthquakes in a region of Earth's crust. This ratio can change as magma rises through the crust to the summit of a volcano, the researchers reported in a study published Oct. 8 in the journal Science Advances.

"Changes in the b value over time reflect how the stress inside the volcano is evolving," study lead author Marco Firetto Carlino, a geophysicist at INGV's Etna Observatory, told Live Science in an email. "Since magma ascent induces stress changes within the crust, tracking the b value can help reveal different stages of magma transfer from depth to the surface."

The b value is an established parameter in volcanology, but the researchers examined it in a novel way, with an updated statistical model. By compiling 20 years' worth of earthquake data from Mount Etna, they found a "very strong" correlation between the b value and Etna's volcanic activity, Firetto Carlino said.

Mount Etna sits in the collision zone between the African and European tectonic plates. As a result, a vertical fracture in Earth's crust known as a strike-slip fault underlies the volcano, thus facilitating the rise of magma to the surface, according to the study.

The crust beneath Mount Etna is up to 19 miles (30 km) thick. Magma rises through this volume before an eruption, but instead of replenishing a single magma chamber, the molten rock feeds a series of interconnected storage zones that are embedded in the crust at different depths.

The deepest magma storage zone is 7 miles (11 km) below sea level, Firetto Carlino explained, and it feeds an intermediate storage system with different zones likely extending 2 to 4 miles (3 to 7 km) deep. As magma rises, it travels through an intricate network of fractures and eventually reaches the last storage zone, which is located above sea level inside the volcano edifice.

The researchers had a wealth of data to work with and extract b values from, due to Etna's frequent activity. They analyzed seismic patterns in the 19 miles of crust beneath the volcano from 2005 to 2024, paying particular attention to how these patterns varied between crustal regions.

Generally, regions of Earth's crust with active magma storage zones show higher b values than more stable regions do, because the active zones experience more small earthquakes than bigger ones.

"This happens because rocks affected by moving magma become weak and highly fractured," Firetto Carlino said. "For example, when magma inside a storage releases volatiles, they permeate the surrounding rocks, making it easier for small fractures to slip."

Conversely, regions of Earth's crust that are more stable typically experience more big earthquakes than smaller ones, because it takes more force to break the rock. "Rocks with good mechanical properties can store stress for longer periods," Firetto Carlino said. "When they finally break, they produce larger earthquakes, corresponding to lower b values."

So, by tracking the b value over time, it may be possible for researchers to follow the movement of magma through the deep crust to the first storage zone, up from there to the intermediate storage system, and up again to the shallow storage zone. This method could help experts estimate the timings of eruptions at Mount Etna.

"Monitoring the b value offers a powerful way to track magma movement within the crust and assess the volcano's evolving state before eruptions," Firetto Carlino said.

Mount Etna was a good test for the study due to its layered magma storage zones and enormous seismic catalog, but the results might also apply elsewhere.

"In principle, the b value could also be used to track magma movements in other volcanic areas, provided that a sufficient number of earthquakes is available and that their locations are distributed across different crustal sectors, well constrained by previous geological studies," Firetto Carlino said.

A "Big One" on the Cascadia subduction zone in the Pacific Northwest might trigger a similarly serious earthquake on California's San Andreas Fault, new research suggests.

The findings are based on sediments taken from the seabed off the coast of Cape Mendocino, California and offshore Oregon. It's at Cape Mendocino that California's famous San Andreas fault ends and the Cascadia subduction zone begins.

These are two very different fault systems, but the sediment record suggests that in the past, at least three San Andreas earthquakes have happened within hours to a couple of days after large Cascadia quakes. Another seven or so may have occurred within decades to years or less. There are uncertainties in the dating and records, however.

But if the two fault systems are, in fact, synchronized, it could be a real problem for disaster relief, said study first author Chris Goldfinger, a paleoseismologist and professor emeritus at Oregon State University.

"Having these things side by side would really be a tough one," Goldfinger told Live Science. "There'd be not enough resources to respond to even one of these very well, and two of them would be really difficult."

Earthquake potential

Cascadia can create extremely powerful earthquakes. Famously, in 1700, the region experienced a quake thought to be between magnitude 8.7 and 9.2 that sent destructive tsunami waves all the way to Japan. These quakes are caused by movement of three oceanic plates (the Explorer, the Juan de Fuca, and the Gorda) slipping beneath the North American continent.

The San Andreas Fault, on the other hand, is a strike-slip fault where rock masses on either side of the fault move past each other horizontally.. The largest known quake on the northern San Andreas was the 1906 San Francisco earthquake of approximately magnitude 7.9. Because the fault runs through densely populated areas, it could do a great deal of damage, as in the 1989 Loma Prieta earthquake that killed 63 people.

The two fault systems meet off the coast of Mendocino in an area known as the "triple junction." Goldfinger and his colleagues were on a research cruise in 1999 drilling core samples from the ocean floor in Cascadia, looking for signs of ancient earthquakes. When large earthquakes happen on land, they can trigger underwater flows of sand and sediment known as turbidites. Turbidites follow a pattern where coarse sediment settles out of the water first, creating a layer. Finer sands and silt follow, forming another layer.

On that cruise, however, a mix-up led to the ship traveling 60 miles from where they'd meant to be. The scientists, who were trying to nap between working, didn't realize the error until the ship arrived.

"I was just like, 'Oh no, we’re like halfway to San Francisco,'" Goldfinger remembers.

He decided to take a core sample in that spot anyway. When the team later analyzed the sample, they realized it contained a mystery. The turbidites in the sample didn't have the coarse layer on the bottom and the finer layer on top, as was typical.

"This original core of the San Andreas had deposits that looked like they were upside-down," Goldfinger said. "The sand was at the top."

Upside-down evidence

The researchers had no explanation for this flip-flopped pattern. Nor, at first, did they have an explanation for another strange mystery of these offshore samples: Cores taken south of the triple junction, in the realm of the northern San Andreas, seemed to show earthquakes that matched eerily well to the timing of earthquakes taken north of the triple junction in Cascadia. In the last 1,300 years, they found, there were 18 likely earthquake-generated turbidites in Cascadia and 19 offshore from the northern San Andreas. Ten of those appeared to be deposited within 50 to 100 years of each other.

Even weirder, in three cases, the coarse sand of the upper layer of these flip-flopped turbidites was mixed into the finer sand of the lower layer, suggesting the upper layer had settled while the bottom layer was still in motion. That would mean that the two layers were deposited within hours to days of one another. These three events included the 1700 Cascadia quake, as well as quakes 1,200 years ago and 1,500 years ago.

It took many years to conduct additional radiocarbon dating, gather corresponding earthquake records from other sources like lakebeds in California and ponder the meaning of these bizarre "doublet" turbidites. But ultimately, Goldfiner said, he came to realize that these San Andreas turbidites might represent two different quakes: One, from the far-off Cascadia region, which shook off only lighter silt and sand, and the second, from a soon-after San Andreas quake that was locally stronger and could move coarser material.

"That would explain it," Goldfinger said. "It would explain the match-up of ages… that's what broke the dam."

The researchers argue in their new paper, published Sept. 29 in the journal Geosphere, that large quakes in Cascadia can transfer stress to the neighboring San Andreas, which then leads to a San Andreas earthquake not long after.

Earthquakes triggering one another are not unheard of, said Harold Tobin, a seismologist at the University of Washington who was not involved in the research. But most of those examples occur in the same fault zone.

"There aren’t really examples that I can think of where two different types of plate boundary faults are so tightly coupled as what’s proposed in this paper," Tobin told Live Science. The work was carefully done, he said, but "for me, the jury is still out on whether there could be other explanations for the sediment deposits or not."

Cascadia and the northern San Andreas region are highly seismically active, and many other faults could trigger earthquakes, Tobin said. Sedimentary deposits are complicated to interpret, and there are uncertainties inherent in radiocarbon dating.

"There are an awful lot of reasons why this is a complicated system," Tobin said. "This is an intriguing set of observations, but it’s going to take even more detailed work to corroborate."

Goldfinger said he hoped the work would inspire Cascadia geologists and San Andreas geologists to work more closely together to do that detailed work.

"We all have a lot to learn from each other," he said. "I’m hoping it will ratchet up the quality of science on both sides."

An artificial intelligence (AI) model has revealed never-before-seen geological structures at Italy's Campi Flegrei volcano, including a clear "ring fault" that could unleash magnitude 5 earthquakes.

So far in 2025, Campi Flegrei has produced five earthquakes above magnitude 4, and the volcano has been showing signs of unrest since 2005. But most of the earthquakes triggered in the region are going undetected, according to a new study that used AI to pinpoint tens of thousands of seismic events that have gone under the radar over the past few years.

"We've known that this is a risky place for a long time," study co-author William Ellsworth, a professor emeritus of geophysics at Stanford University, said in a statement. "Now we're seeing for the first time the geologic structures that are responsible."

Over the past 40,000 years, Campi Flegrei has produced two of the largest eruptions in Europe, and evidence suggests the volcano's earlier history was just as explosive. Scientists have been recording unrest at Campi Flegrei since the 1950s, but monitoring efforts increased in the 1980s after a swarm of 16,000 earthquakes prompted the evacuation of 40,000 residents.

To investigate modern threats from Campi Flegrei, Ellsworth and his colleagues developed an AI tool capable of identifying earthquakes that previous methods couldn't pick out.

Traditionally, seismologists identify earthquakes by analyzing seismograms, which are graphs with wiggly lines that represent shaking in the ground over time. Researchers look for a sudden increase in the wiggles' size, and this process is known as "phase picking," said study co-author Greg Beroza, a professor of geophysics at Stanford University.

"That's a simple and often effective means of picking a phase, but it doesn't 'learn' how to do it better so that it improves with time," Beroza told Live Science in an email. "In our approach, we train a machine learning model to pick phases. We base it on the collection of millions of examples where experts have done this already, and our method is designed to learn how to do this more effectively."

The team chose to have their tool analyze Campi Flegrei before other volcanoes for several reasons, including there being an urgent need to better understand this volcano's behavior, Beroza said. More than 360,000 people live inside Campi Flegrei's 7-mile-long (11 kilometers) caldera, and roughly 1.5 million people reside in the wider area. Unrest over the past 20 years ticked up in 2018 — and while there are currently no signs of an eruption, a particularly violent or shallow earthquake could present a huge danger to people as well as damage buildings, according to the statement.

The results from the AI tool, published Sept. 4 in the journal Science, reveal that three-quarters of earthquakes at Campi Flegrei between 2022 and mid-2025 went undetected. While traditional methods documented 12,000 earthquakes in this period, AI shows the number was closer to 54,000.

By mapping the location of these earthquakes, the researchers discovered faults — cracks in Earth's crust that can grind against each other and cause earthquakes — that previous methods hadn't highlighted. Notably, the team found two faults converging beneath Pozzuoli, a town west of Naples where evacuations took place in the 1980s. The location of these faults suggests "an earthquake in the magnitude 5 range is not out of the question," Ellsworth said.

This wasn't the only striking finding. Pozzuoli experienced uplift in the 1980s, and the same is happening again now, with the ground beneath the town rising by about 4 inches (10 centimeters) each year. It turns out, the area of uplift is encircled by several faults, forming a thin, well-marked "ring fault" that extends offshore, according to the statement.

"Our Italian colleagues were surprised to see the ring so clearly," study lead author Xing Tan, a doctoral student in Beroza's lab, said in the statement. "They expected to see something in the south where previous data had revealed scattered seismicity, but in the north, they'd never seen it so clearly."

Seismic activity along the ring fault could help predict changes in the system, as well as hint at the magnitudes of future earthquakes, Beroza said. But it doesn't provide new information about the likelihood or timing of Campi Flegrei's next eruption.

"All the analyzed seismicity from 2022 to mid-2025 is shallow, at depths above 4 kilometers (2.5 miles) and does not indicate any migration of magma towards the surface," Beroza said.

The team's results for Campi Flegrei indicate that the AI tool could be useful for other volcanoes, too. Places that have recently seen an uptick in seismic activity, such as Santorini in Greece, could benefit from a clearer understanding of the underlying geology, the researchers said in the statement.

A 1954 earthquake that rattled Northern California was likely caused by the infamous Cascadia Subduction Zone, a new study finds.

The linking of the magnitude 6.5 quake with this particular seismic zone is important, because the Cascadia Subduction Zone, which stretches from northern California to Vancouver Island in Canada, is not known to give off many small or medium quakes. In seismology parlance, the fault is "locked," or unmoving. The last known rupture was a massive magnitude 9 earthquake in 1700 that caused landslides and an enormous tsunami that was so powerful that waves over 16 feet high (5 meters) hit Japan, according to the U.S. Geological Survey.

In modern times, though Cascadia "has been eerily quiet," study co-author Lori Dengler, a retired seismologist from Cal Poly Humboldt and one of the study’s co-authors, said in a statement. "We don't have smaller earthquakes, and that’s not something you usually see in subduction zones."

That lack of small earthquakes in the decades since scientists started monitoring faults with seismometers and other instruments means they have a limited sense of Cascadia's behavior. But the new research, published in the Bulletin of the Seismological Society of America on Tuesday (Aug. 19), suggests that the fault has possibly ruptured on a smaller scale within recent memory. The study re-evaluated a Dec. 21, 1954 quake that shook the Humboldt Bay, California area just before noon. Residents reported strong, rapid ground motion that toppled chimneys.

Related: San Andreas fault could unleash an earthquake unlike any seen before, study of deadly Myanmar quake suggests

The quake was recorded by the seismology equipment of the time, which included a few accelerometers that could measure ground motion and older seismographs that used a suspended pen to draw a continuous line on a roll of paper, recording the shaking of earthquakes with the resulting squiggly lines. The researchers had to collect these old paper records and scan them digitally. They also gathered records from farther-flung seismic stations to get a better sense of the earthquake's epicenter and its depth.

With fragmented data, researchers had previously proposed 14 different epicenters for the quake. The new study honed in on a new, more precise location: Fickle Hill, a small forest community along a two-lane road not far from the larger city of Arcata. The researchers, led by retired University of California Berkeley seismologist Margaret Hellweg, also found that the fault that caused the quake likely ruptured between about 6.8 miles and 8.7 miles (11 to 14 kilometers) below the surface.

Arcata sits in a particularly interesting earthquake region. It's not far from the offshore "triple junction," where the Pacific oceanic plate meets the Gorda oceanic plate and the North American continental plate. It's also in the transition zone between the San Andreas fault zone (where the North American plate and the Pacific plate slide past each other) and the Cascadia Subduction Zone (where the oceanic Juan de Fuca plate dives under the North American plate).

Most quakes near Humboldt originate on the Gorda plate. But the Fickle Hill quake didn't, the researchers found. Based on the depth and the direction of the earthquake waves, the quake instead seems to have come from the Cascadia Subduction Zone.

That makes Fickle Hill one of only two known possible Cascadia quakes since 1700. (The magnitude 7.2 Cape Mendocino quake in 1992 might also have been a Cascadia quake, though that is still hotly debated.)

The finding would suggest that Casadia does not have to rupture all at once, causing devastatingly huge quakes, but that it can also break in segments, creating smaller temblors. Though the new research doesn't yet translate to any predictions of what Cascadia might do in the future, reviewing existing data can help improve scientists' understanding of the area's tectonics, the researchers wrote in their paper, ultimately helping improve their estimation of the earthquake hazard for the Pacific Northwest.

Faults like San Andreas don't necessarily repeat past behavior, which means the next big earthquake in California has the potential to be larger than any seen before, a new study suggests.

The fresh insights into fault behavior came from studying Myanmar's devastating March earthquake, which killed more than 5,000 people and caused widespread destruction. Scientists found that the fault responsible, an "earthquake superhighway" known as the Sagaing Fault, ruptured across a larger area, and in places that they wouldn't have expected based on previous events.

Faults are fractures in Earth's crust. Stress can build up along the faults until eventually the fault suddenly ruptures, causing an earthquake. As the Sagaing and San Andreas faults are similar, what happened in Myanmar could help researchers better understand what might happen in California.

"The study shows that future earthquakes might not simply repeat past known earthquakes," study co-author Jean-Philippe Avouac, a professor of geology and mechanical and civil engineering at Caltech, said in a statement. "Successive ruptures of a given fault, even as simple as the Sagaing or the San Andreas faults, can be very different and can release even more than the deficit of slip since the last event."

Related: Almost half of California's faults — including San Andreas — are overdue for earthquakes

The San Andreas Fault is the longest fault in California, stretching about 746 miles (1,200 kilometers) from the state's south at the Salton Sea to its north off the coast of Mendocino. In 1906, a rupture in the northern section of the fault caused a devastating magnitude 7.9 earthquake that killed more than 3,000 people, according to the U.S. Geological Survey.

Earthquakes are notoriously unpredictable, but geologists have long warned that the San Andreas Fault will produce another massive earthquake at some point. For instance, the area nearest to Los Angeles has a 60% chance of experiencing a magnitude 6.7 or greater in the next 30 years, according to the USGS.

The 870-mile-long (1,400 km) Sagaing Fault is similar to the San Andreas Fault in that they are both long, straight, strike-slip faults, which means the rocks slide horizontally with little or no vertical movement.

Geologists were expecting the Sagaing Fault to slip somewhere along its extent. Specifically, they thought that the rupture would take place across a 190-mile-long (300 km) section of the fault where no large earthquakes had occurred since 1839. This expectation was based on the seismic gap hypothesis, which anticipates that a stuck section of a fault — where there hasn't been movement for a long time — will slip to catch up to where it was, according to the statement.

However, in the case of Sagaing, the slip occurred along more than 310 miles (500 km) of the fault, meaning that it caught up and then some. The researchers used a special technique to correlate satellite imagery before and after the event. Those images revealed that after the earthquake, the eastern side of the fault moved south by about 10 feet (3 m) relative to the western side. The scientists say that the imaging technique they used could help improve future earthquake models.

"This earthquake turned out to be an ideal case to apply image correlation methods [techniques to compare images before and after a geological event] that were developed by our research group," study first author Solène Antoine, a geology postdoctoral scholar at Caltech, said in the statement. "They allow us to measure ground displacements at the fault, where the alternative method, radar interferometry, is blind due to phenomenon like decorrelation [a process to decouple signals] and limited sensitivity to north–south displacements."

Six volcanoes in far eastern Russia are now erupting following the 8.8 magnitude earthquake and aftershocks that shook the region last week.

Klyuchevskaya erupted first, on July 30. It had already shown signs of unrest before the earthquake, and experts deduced that the quake likely intensified the eruption but didn't trigger it. However, it's difficult to know the exact effect of the earthquake on the volcano. Eruptions of nearby volcanoes Shiveluch, Bezymianny, Karymsky, Avachinsky and Krasheninnikov soon followed and continue through today.

All of the volcanoes sit on the Ring of Fire, a geological feature notorious for volcanic and seismic activity.

The area around this parade of erupting volcanoes, called the Kamchatka Peninsula, is sparsely populated, so there doesn't seem to be an active threat to local communities. However, the eruptions could pose a risk to planes if they were to fly through ash plumes, Harold Tobin, a seismologist at the University of Washington, told Live Science in an email.

Despite the recent spate of eruptions, experts say this kind of volcanic activity is not out of the ordinary. "About 40 to 50 volcanoes are actively erupting around the world at any given time. Right now is no different," Tobin said. "Kamchatka is a very volcanically active region."

Were the eruptions caused by the earthquake?

There is no clear or singular way an earthquake can cause volcanic eruptions, but these two events can co-occur at subduction zones, areas where one tectonic plate dives beneath another.

Related: Russian volcano grows 'devil horns' and spits out 1,000-mile-long river of smoke — Earth from space

"It is not unprecedented for a large subduction zone earthquake to trigger volcanic eruptions," Paul Segall, a geophysicist at Stanford University, told Live Science in an email.

The largest earthquake ever recorded — a magnitude 9.5 quake that struck Valdivia, Chile, in 1960 — was followed by several volcanic eruptions. "The earthquake changed the stress in [Earth's] crust, which may have made it easier for magma to rise to the surface," Segall said. The shaking of the ground by the earthquake also may have contributed to the eruptions by changing the movement of magma beneath Earth's surface.

Both these mechanisms could have played a role in the Chilean eruptions, but it's still too soon to characterize the recent Russian events, Segall said.

Klyuchevskoy was already showing signs of activity prior to the earthquake, but "it did likely increase in the vigor of the eruption, including some ash emission," a U.S. Geological Survey representative told Live Science on July 30.

The most notable aspect of this chain of events was the eruption of Krasheninnikov for the first time in about 500 years. "The timing is either a very strong coincidence or its magma system was perturbed by strong seismic waves and triggered the eruption," Tobin explained. "It's very hard to determine which is true for a single given eruption."

Additionally, the Ministry of Emergency Situations of Russia for the Kamchatka Territory reported increased thermal activity of a seventh nearby volcano, Mutnovsky. Satellite images revealed a thermal anomaly at the volcano, which has yet to erupt, but scientists say they can't predict if or when it might blow.

US volcano quiz: How many can you name in 10 minutes?

A major fault in the Yukon, Canada, that has been quiet for at least 12,000 years may be capable of giving off earthquakes of at least magnitude 7.5, new research suggests.

Based on the amount of strain the Tintina fault has accumulated over the past 2.6 million years, it is now under an amount of stress that could lead to a large quake within a human lifespan, researchers reported July 15 in the journal Geophysical Research Letters. The finding may require experts to rethink the earthquake danger in the region, the study authors said.

An magnitude 7.5 earthquake would threaten a few small communities within the remote Yukon. But the finding that the Tintina fault may be capable of such a large quake is notable because the fault has been quiet since before the last ice age ended.

"Major ancient faults like that can remain as weak zones in the Earth's crust and then focus ongoing tectonic strain," Theron Finley, a geoscientist who conducted the research while earning his doctorate at the University of Victoria in Canada, told Live Science.

The Tintina fault is over 620 miles (1,000 kilometers) long and stretches from northeast British Columbia through the Yukon and into Alaska. On its southern end, it connects to the Rocky Mountain Trench fault, which creates a huge valley through southern Canada and northern Montana.

Forty million years ago, during the Eocene epoch, one side of the Tintina fault slid 267 miles (430 km) against the other at a rate of about half an inch (13 millimeters) each year. Today, the fault seems quiet, with only occasional small earthquakes of magnitude 3 to 4 in some sections.

However, "there has always been a question of whether it's still a little bit active or still accumulating strain at a slower rate," Finley said.

To find out, Finley and his colleagues used high-resolution satellite data and lidar imagery of the Yukon. Lidar is a type of laser measurement that allows for precise imaging of topography while ignoring vegetation — an important tool for an area blanketed with forest. With this imagery, the researchers looked for signs on the surface of ancient earthquakes, such as fault "scarps," where the ground moved sharply upward on one side of the fault.

"Those features can be hundreds of kilometers long in some cases, but they're only on the order of a couple meters high or wide, so we need the really high-resolution topographic data," Finley said.

The researchers determined the dates of each rumple of the landscape by using traces left by incursions of glaciers, which occurred at known intervals 12,000 years ago, 132,000 years ago, and 2.6 million years ago. They found that over 2.6 million years, the fault's sides moved relative to each other by about 3,300 feet (1,000 m). Over the past 136,000 years, the opposing sides of the fault moved about 250 feet (75 m). It probably took hundreds of earthquakes to accumulate all that movement, Finley said, which translates to between 0.008 and 0.03 inches (0.2 to 0.8 mm) per year.

The fault has not had a large earthquake that ruptured the ground surface for at least 12,000 years, according to the study. The researchers estimate that in that period, the fault has accumulated about 20 feet (6 m) of built-up strain — movement that hasn't yet been released in an earthquake. The fault probably breaks at between 3 and 33 feet (1 to 10 m) of strain, Finley said, so it's in the range where it might normally fracture.

"It could still be many thousands of years before it reaches the threshold where it ruptures, but we don't know that and it's very hard to predict that," Finley said.

Because the fault is active in its Alaska portion, it's not surprising to learn that the Tintina fault could be a sleeping giant, said Peter Haeussler, a geologist emeritus at the U.S. Geological Survey in Alaska. He said he was glad to see the evidence emerge."Somebody's finally found evidence for activity on the Tintina fault in the Yukon," Haeussler told Live Science.

"It ups the seismic hazard for this neck of the woods a little bit," he added, but not enormously, as the region was already known to be seismically active. The fault runs near Dawson City, Canada, Finley said, which has a population of about 1,600 and would be most threatened by a large quake. There are also mining facilities in the area, as well as a risk of quake-triggered landslides.

To better understand the risk, geoscientists will need to excavate trenches in the fault to look for rock layers that show past earthquakes and how often they occurred.

"Right now, we just know that many have occurred, but we don't have a sense of how frequently," Finley said. "Is 6 meters a lot of strain, or is it more likely there's a long way to go before another rupture?"

Klyuchevskoy volcano in eastern Russia began erupting shortly after a powerful 8.8 magnitude earthquake and several aftershocks shook the same area.

"A descent of hot lava is observed on the western slope," the Geophysical Center of the Russian Academy of Sciences said in a translated post on the messaging app Telegram Wednesday (July 30).

The Kamchatka branch of the academy captured the eruption on cameras observing the volcano. In the Telegram post, they reported seeing "explosions" as a "powerful glow above the volcano."

The ash plume from the eruption extended at least 1.5 miles (2.5 kilometers) above and 36 miles (58 km) east of the volcano, the Kamchatkan Volcanic Eruption Response Team said on Telegram. The group warned that explosions of ash up to 5 miles (8 km) high could occur at any time.

Details about the full extent of the eruption and damages are unknown at this time.

In the weeks leading up to the earthquake, "the volcano was showing signs of unrest," a U.S. Geological Survey (USGS) representative told Live Science in an email. On July 21, a team of Russian scientists found a lava lake at the summit of the volcano, signaling that the volcano was primed for eruption.

Related: Russian volcano grows 'devil horns' and spits out 1,000-mile-long river of smoke — Earth from space

"While yesterday's large earthquake did not cause the eruption to begin, it did likely increase in the vigor of the eruption including some ash emission," the USGS representative said.

Klyuchevskoy, which rises 15,597 feet (4,754 meters) above sea level, is the tallest active volcano in Asia and Europe, according to NASA's Earth Observatory. The volcano sits on Russia's Kamchatka Peninsula, a hotspot for geologic activity due to its position on the Pacific Ring of Fire.

The eruption came hours after an 8.8 magnitude earthquake — tied for the sixth-most-powerful earthquake ever recorded — struck on the same peninsula Wednesday at 11:24 a.m. local time. The earthquake could generate tsunami waves higher than 10 feet (3 m) above the tide on the coasts of Hawaii, Ecuador and Russia, the U.S. National Tsunami Warning Center warned after the earthquake struck.

The volcano is about 280 miles (450 km) north of Petropavlovsk-Kamchatsky, the regional capital city. It last erupted in late 2023, when it spewed a 1,000-mile-long (1,600 km) river of dust and ash that reached up to 7.5 miles (12 km) above Earth's surface.

This eruption is "typical activity at this very active volcano," the USGS representative said. "The volcano is in a remote area and this eruption is consistent with other recent past eruptions."

Tsunami warnings have been issued in regions across the Pacific, including Hawaii, Alaska, Russia and Japan, following a magnitude 8.8 "megaquake" — the joint-sixth largest ever recorded — that hit off Russia's Far Eastern Kamchatka Peninsula at 11:25 a.m. local time (18:25 p.m. EST) on Wednesday morning (July 30), according to the U.S. Geological Survey (USGS).

Tsunami waves could reach higher than 10 feet (3 meters) above tide level along the coasts of Hawaii, Ecuador and Russia, according to a warning issued by the U.S. National Tsunami Warning Center at 11:07 p.m. EST on July 29. The first waves reached Hawaii, with a 4 foot (1.2 m) wall of water recorded by the Pacific Tsunami Warning Center (PTWC) off the coast of Oahu, the BBC reports.

"A tsunami has been generated that could cause damage along coastlines of all islands in the state of Hawaii," the PTWC said in a bulletin. "Urgent action should be taken to protect lives and property."

Honolulu's mayor Rick Blangiardi warned residents to move to higher ground and Hawaii's governor, Josh Green, urged people to immediately evacuate coastal regions.

In a news conference reported by CNN, Green said "it will not hit one beach, it will wrap around the islands."

In Japan, officials have told more than 1.9 million people to evacuate as waves measuring over 4 feet (1.2 m) hit the country's north and east coasts, CNN reports.

Footage of tsunami waves hitting the Russian coastal town of Severo-Kurilsk in Kamchatka, shows water flooding buildings on the port.

In North America, tsunami advisories are also in place along the coasts of California, Oregon, Washington, British Columbia, Alaska and the Aleutian Islands. Waves measuring between 3 and 10 feet (1 to 3 m) are also possible along the coasts of Chile, Costa Rica, French Polynesia, Japan, Jarvis Island, Johnston Atoll, Kiribati, Midway Island, Palmyra Island, Peru, Samoa and the Solomon Islands, according to the PTWC.

The epicenter of the earthquake was recorded roughly 74 miles (119 kilometers) southeast of Petropavlovsk-Kamchatsky, on the Kamchatka Peninsula, according to the USGS. As of midnight EST, 24 powerful aftershocks reaching magnitudes of over 5.0 were reported in Russia, with two hitting magnitudes of 6.9 and 6.3, respectively.

The Kamchatka earthquake is considered a megaquake as its magnitude is above 8.

The Kamchatka Peninsula is a sparsely populated region located within the Pacific Ring of Fire, a horseshoe-shaped belt of volcanoes known for their explosive volcanic eruptions and intense earthquakes. The ring runs from southern Chile, up the west coast of the Americas, through the islands off Alaska and far eastern Russia and down through Japan and the Philippines.

The volcanoes here arise due to tectonic plates involved in a process called subduction. This movement lowers the melting point of rocks in Earth's mantle, creating pockets of magma that rise to the surface. "What's special about the Ring of Fire is that multiple oceanic plates in the Pacific have subduction boundaries there," Loÿc Vanderkluysen, a volcanologist at Drexel University in Philadelphia, previously told Live Science.

Indeed, it's estimated that 90% of the 34,000 miles (55,000 km) of subduction plate boundaries on Earth are found in the Pacific.

Tectonic movements also trigger earthquakes as the plates squeeze past each other. "There's lots of kicking and screaming as the plates grind against one another," Jeffrey Karson, a professor emeritus of tectonics at Syracuse University in New York, previously told Live Science. "And so that's where the biggest earthquakes on our planet take place."

Due to all this activity, the Ring of Fire is home to about 75% of Earth's active volcanoes and reports 90% of all measured earthquakes.

Indeed, the five largest earthquakes ever recorded have all taken place within this region:

1. Valdivia Earthquake, Chile: magnitude 9.5, 1960

2. Great Alaska Earthquake, U.S.: magnitude 9.2, 1964

3. Sumatra-Andaman Islands Earthquake: magnitude 9.1, 2004

4. Tohoku Earthquake, Japan: magnitude 9.1, 2011

5. Kamchatka Earthquake, Russia: magnitude 9.0, 1952

This latest earthquake comes in joint-sixth place with Chile's Maule Earthquake in 2010 and the Ecuador-Colombia Earthquake in 1906, all with a magnitude 8.8.

The Ring of Fire is an enormous belt of active and dormant volcanoes that surrounds most of the Pacific Ocean. It runs from southern Chile, up the west coast of the Americas, through the islands off Alaska and down Japan to the Philippines. Some geologists also include an Indonesian chain of volcanoes in the ring.

These volcanoes arise because of subduction — the movement of a tectonic plate under a neighboring plate — which lowers the melting point of rock in the mantle. The rock turns to magma, rises to the surface and erupts as a volcano.

But the Ring of Fire does this subduction on a massive scale. "What's special about the Ring of Fire is that multiple oceanic plates in the Pacific have subduction boundaries there," Loÿc Vanderkluysen, a volcanologist at Drexel University in Philadelphia, told Live Science. About 90% of the 34,000 miles (55,000 kilometers) of subduction plate boundaries on Earth are found in the Pacific, Vanderkluysen explained.

This tectonic movement also causes earthquakes. When one plate is forced underneath another, "there's lots of kicking and screaming as the plates grind against one another," Jeffrey Karson, a professor emeritus of tectonics at Syracuse University in New York, told Live Science. "And so that's where the biggest earthquakes on our planet take place."

The Ring of Fire contains about 75% of Earth's active volcanoes and is where 90% of measured earthquakes occur.

What's in a name?

The name Ring of Fire is hotly contested among researchers. "Many scientists hate the term," Vanderkluysen said. For one, it's not actually a complete ring. The volcanoes follow the edges of tectonic plates, which only subduct on the north, east and west of the Pacific.

Also, some areas of the ring have no volcanism at all, such as Peru and central Chile.

In addition, the Ring of Fire includes more than 450 volcanoes in distinct regions. And they all differ in their magma production, storage and the positioning of their subducting plate, Vanderkluysen said.

"Each [volcano] has its own individual history and flavor that, from a research perspective, is more effective to study individually rather than trying to link all the Ring of Fire volcanoes together that are otherwise not geologically linked," he said.

Related: Sleeping subduction zone could awaken and form a new 'Ring of Fire' that swallows the Atlantic Ocean

Some experts believe that the term has taken on a false meaning in popular culture, with the implication that it's one big structure, Erik Klemetti, a volcanologist at Denison University in Granville, Ohio, told Live Science. "It works nicely as a way to describe the fact that there are an awful lot of volcanoes along the edge of the Pacific," he said, but the ring is just "a geographic coincidence of our current moment on Earth."

One big misconception is "the catastrophist notion that all volcanoes in the Ring of Fire are interconnected and that an eruption or earthquake in one location can trigger the whole region with dramatic consequences," Vanderkluysen said. While it's clear to scientists that an eruption in Japan will not trigger an eruption in Chile, for example, the term is sometimes used to suggest that it's possible, he said.

"An immense natural laboratory for volcanism"

Research into the Ring of Fire spreads across many fields. About two-thirds of the volcanoes that have erupted on Earth since 1960 were in the ring, so "just due to sheer numbers, the Pacific region is an immense natural laboratory for volcanism, and explosive volcanism in particular," Vanderkluysen said.

Volcanologists can use data from the ring to learn about the various eruptions that happen there. "Some are steady and erupt without massive build-ups, and others erupt sporadically but catastrophically," Robert Butler, who studies plate tectonics at the University of Aberdeen, told Live Science in an email.

The different kinds of plate interactions in the Pacific serve as "test beds" for learning what leads to different types of eruptions, Klemetti explained.

Klemetti hopes Ring of Fire research will eventually reveal the inner workings of volcanoes that take place miles below sea level. In the next 10 or 20 years, he thinks scientists can learn about where and how magma is stored between eruptions, how long it takes for magma to heat up and understand more about the transition from dormancy to eruption.

Seismologists also study the Ring of Fire, as more than 80% of earthquakes with a magnitude of 8.0 or higher have occurred there. Researchers can investigate quakes in the Ring of Fire to learn more about how the stress builds up in subduction zones before powerful earthquakes, Butler said.

The vast amount of data helps scientists differentiate between types of extreme events and their causes. "It's a general problem we need to sort in geology, the differences between frequent, not too serious events, and those that occur infrequently but are super-devastating," Butler said.

Analyzing volcanoes and earthquakes in the Ring of Fire can help scientists to improve extreme hazard prediction for volcanic eruptions. Scientists estimate that 800 million people — about 10% of the world's population — live within 62 miles (100 kilometers) of an active volcano. "In the future, there will be large volcanic eruptions that might happen close to population centers and might have impacts at the global scale," Marc-Antoine Longpré, a volcanologist at CUNY Graduate Center, told Live Science.

Earthquakes in the ring, and resulting tsunamis, are also of great concern. Researchers could use earthquake data from the Ring of Fire to develop early warning systems or forecasting tools, Vanderkluysen said.

US volcano quiz: How many can you name in 10 minutes?

A first-of-its-kind video showing the ground cracking during a major earthquake is even more remarkable than previously thought. It not only captures a ground motion never caught on video before but also shows the crack curving as it moves.

This curvy movement has been inferred from the geological record and from "slickenlines" — scrape marks on the sides of faults — but it had never been seen in action, geophysicist Jesse Kearse, a postdoctoral researcher currently at Kyoto University in Japan, said in a statement.

"Instead of things moving straight across the video screen, they moved along a curved path that has a convexity downwards, which instantly started bells ringing in my head," Kearse said, "because some of my previous research has been specifically on curvature of fault slip, but from the geological record."

The video — captured by a security camera near Thazi, Myanmar — shows the ground rupturing during a magnitude 7.7 quake that hit the region on March 28. It shows the ground shaking, followed by a crack opening up. These ground ruptures are relatively common during big quakes, but they'd never been caught on video.

Kearse said he watched the video with chills down his spine shortly after it was uploaded to YouTube. On his fifth or sixth viewing, he noticed that the crack was curvy. He and his colleague at Kyoto University, geophysicist Yoshihiro Kaneko, then analyzed the video more closely. They found that the crack curves sharply at first and then accelerates to a peak velocity of about 10.5 feet per second (3.2 meters per second) of movement, slipping a total of 8.2 feet (2.5 meters) in 1.3 seconds. After hitting its top velocity, the crack straightens and slows.

The findings suggest that the curvature happens because stresses on the fault right at the ground surface are lower than the stresses on the fault deeper in the Earth. This creates an uneven pattern in how the fault moves. "The curvature holds important information about the dynamics of the rupture," Kearse said in an annotated video of the slip he posted on YouTube.

Related: The San Andreas Fault: Facts about the crack in California's crust that could unleash the 'Big One'

The differing stresses at the surface push the fault off its course, "and then it catches itself and does what it's supposed to do," Kearse said in the statement.

The dynamics of these curvatures depend in part on which way the rupture travels, so an understanding of the curves can reveal clues about how past earthquakes unfolded and help scientists better predict future ground ruptures.

The research was published today (July 18) in the journal The Seismic Record.

Editor's Note: This article was updated at 8:20 p.m. EDT to note that the new research has now been published in The Seismic Record.

The ancient meteor impact that formed Arizona's Barringer Crater sent shock waves through the Grand Canyon — likely triggering a landslide that dammed the Colorado River, a new study suggests.

Barringer Crater, also called Meteor Crater, formed between 53,000 and 63,000 years ago, when a giant cosmic "curveball" punched a hole in Earth's surface. The force of the impact traveled more than 100 miles (160 kilometers) to the Grand Canyon, which may have caused an entire cliff face to collapse into the river, scientists have found.

The discovery, described July 15 in the journal Geology, has linked two major events that were thought to be completely unrelated.

"There are other possibilities, such as a random rockfall or local earthquake within a thousand years of the Meteor Crater impact that could have happened independently," Karl Karlstrom, a professor of Earth and planetary sciences at the University of New Mexico and lead author of the study, said in a statement.

But the events described are extraordinary, Karlstrom said — and they happened within a suspiciously small time frame, suggesting that they were related.

Related: Grand Canyon Dragon wildfire burns down historic lodge and triggers toxic gas leak

Researchers already knew that the Colorado River flooded the Grand Canyon sometime in the Late Pleistocene (129,000 to 11,700 years ago). They determined this by analyzing animal figurines carved out of driftwood, which Karlstom's father and colleagues unearthed in a cavern called Stanton's Cave in the 1960s, according to the statement. With techniques available at the time, the researchers dated the driftwood and found it was more than 35,000 years old. (The figurines themselves were carved between 3,000 and 4,000 years ago.)

Stanton's Cave sits 150 feet (46 meters) above river level, so the water must have risen to deposit driftwood there — but the reason remained unknown. "It would have required a ten-times bigger flood level than any flood that has happened in the past several thousand years," Karlstrom said.

"Rare and unusual occurrences"

Subsequent analyses using more advanced techniques suggested the driftwood was 43,500 years old, and the new study pushed the date back even further, to 56,000 years ago. Dating the driftwood was a crucial step in figuring out how it got to Stanton's Cave in the first place, Karlstrom said.

But the researchers needed more evidence to complete the puzzle, so they searched similar caves in the area. "From numerous research trips, Karl and I knew of other high-accessible caves that had both driftwood and sediment that could be dated," study co-author Laura Crossey, also a professor of Earth and planetary sciences at the University of New Mexico, said in the statement.

Several labs examined the additional driftwood samples, and all came back with dates consistent with a flooding event 56,000 years ago. The locations of the caves pointed to this event being a landslide near Nankoweap Canyon, which is downstream of Stanton's Cave. The landslide may have been so big that it created a dam on the Colorado River, forming a lake that stretched for miles upstream. As a result, water levels may have risen high enough to deposit driftwood in the caves, according to the statement.

Around the same time as these results appeared, study co-author David Kring, principal scientist at the Lunar and Planetary Institute in Houston, was recalculating the age of the Barringer Crater. Kring's work showed that the meteor impact occurred around 56,000 years ago, according to the statement.

Kring had previously calculated that the Barringer meteor impact unleashed a magnitude 5.4 earthquake, and when the researchers came together to work on the new study, he determined that the residual effect at the Grand Canyon would have been the same as a 3.5 magnitude earthquake. This could have been enough to disintegrate a cliff face, according to the statement.

"The team put together these arguments without claiming we have final proof," Karlstrom said. "Nevertheless, the meteorite impact, the massive landslide, the lake deposits, and the driftwood high above river level are all rare and unusual occurrences."

With dates that all converge around 56,000 years ago, it seems credible for the events to be related, he said.

Giant sand mounds beneath the North Sea have puzzled scientists for years. Now, researchers have discovered that these mysterious structures were created by a geological process that has never been seen on such a huge scale.

Seismic data and rock samples from the northern North Sea, off the coast of Norway, suggest that these miles-wide mounds sank millions of years ago, lifting up older, less-dense "ooze" beneath. The findings could help scientists learn more about future carbon storage options, the researchers wrote in the new study, which was published June 21 in the journal Communications Earth and Environment.

Researchers have known about these mounds buried beneath the seabed for years but haven't reached a consensus regarding the structures' origins. Proposed explanations have included landslide deposits, sandstone pushed up from below, or mud forced through brittle rock.

Now, using a three-dimensional seismic dataset covering the northern North Sea, along with rock samples, researchers examined the mounds and the surrounding regions. They found that the structures were surrounded by older, low-density "ooze," composed in large part of the fossil remains of ancient microorganisms.

The mounds were chemically similar to nearby sands that appear later in the geological record. In some places, the mounds were connected to these sands via fractures in the rock. This suggests that the mounds were made of younger sands that sank beneath the older, lighter ooze below.

The sunken sands have jumbled the expected pattern in the geological record. Usually, older layers of rock are buried deeper than younger sediment, leaving a record of the processes that shaped the landscape over time.

"This discovery reveals a geological process we haven't seen before on this scale," study co-author Mads Huuse, a geophysicist at the University of Manchester in the U.K., said in a statement. "What we've found are structures where dense sand has sunk into lighter sediments that floated to the top of the sand, effectively flipping the conventional layers we'd expect to see and creating huge mounds beneath the sea."

Earthquakes or changes in pressure may have caused the sands to behave like a fluid, thus enabling it to flow through fractures in the seabed and slip beneath rigid sections of the ooze. The researchers dubbed these large, sinking mounds "sinkites." The ooze rafts, buoyed upward, were named "floatites."

"This research shows how fluids and sediments can move around in the Earth's crust in unexpected ways," Huuse said.

The team originally studied these mounds as a possible location for carbon dioxide storage. Before beginning any carbon storage efforts in the region, scientists will need to understand how well and how safely the area can hold on to that carbon.

"Understanding how these sinkites formed could significantly change how we assess underground reservoirs, sealing, and fluid migration — all of which are vital for carbon capture and storage," Huuse said.

The San Andreas Fault is California's longest and most famous fault. At this fracture zone, two plates of Earth's crust move past each other. It stretches from the Salton Sea in Southern California to off the coast of Mendocino in Northern California. On the inland side of the fault, the North American Plate moves southeast. Toward the coast, the Pacific Plate creeps northwest.

The San Andreas is capable of creating big, destructive earthquakes. Earthquakes are measured in magnitude on a scale that starts at zero. In this scale, each whole number represents an earthquake 10 times as large as the one before it. Most earthquakes under magnitude 2.5 aren't felt, while 2.5- to 5.4- magnitude quakes usually cause some shaking but not much damage. Quakes of 5.5 magnitude and higher cause damage to buildings, and earthquakes over 7.0 are considered major.

In 1906, the northern section of the fault shook San Francisco and the Bay Area with a 7.9 magnitude quake, which caused a devastating fire in the city and killed more than 3,000 people, according to the U.S. Geological Survey. In 1857, the southern section of the fault shook and created a quake thought to be just as large. Only two people died, because California had a tiny population at the time. Geologists warn that the San Andreas will give off a large earthquake again — the only question is when.

5 fast facts about the San Andreas Fault

• Over the past 3 million years, the San Andreas Fault has moved an average of 2 inches (56 mm) per year.
• If that rate continues, Los Angeles and San Francisco will be next-door neighbors in 15 million years!
• The 1857 Fort Tejon quake on the southern San Andreas Fault lasted between one and three minutes.
• During the 1906 Great San Francisco earthquake, 296 miles (477 km) of the fault moved.
• The San Andreas Fault was discovered just 11 years before the 1906 earthquake by geologist Andrew Lawson, who worked at the University of California, Berkeley.

Everything you need to know about the San Andreas Fault

San Andreas Fault pictures

Discover more about earthquakes

• Why can earthquakes happen far from plate boundaries?
• The 20 largest recorded earthquakes in history
• Nearly 75% of the U.S. is at risk from damaging earthquakes

California is an earthquake oddball in that the state's faults are more likely to be "overdue" compared with faults elsewhere in the world, new research finds.

The study could help geoscientists make more accurate calculations of when faults are likely to break and cause earthquakes — even in misfit California, said study lead author Vasiliki Mouslopoulou, a research geoscientist at the National Observatory of Athens in Greece.

"The main message to take away is that everyone could benefit, including California," Mouslopoulou told Live Science.

Mouslopoulou and her co-authors were interested in studying the recurrence intervals between earthquakes on faults with a long geological record of their ruptures. Earthquake scientists use these records to calculate the chance of a future quake on the fault by comparing the time since the last known major earthquake to the average time between two large earthquakes on the fault throughout history. If the rocks of the fault show signs of rupturing every 150 years and it's been 200 years since the last earthquake, that quake is said to be "overdue."

Many of California's faults, including the southern portion of the San Andreas, are overdue, Mouslopoulou said. She and her colleagues wanted to compare this overdue pattern to the patterns in other regions of the world.

They gathered records from the state and four other quake-prone regions: Japan, Greece, New Zealand, and the Basin and Range province, which covers much of Nevada, Utah, Arizona and northwestern Mexico. These geological records come from trenches that were dug into fault lines so researchers can see when and where the ground broke in the past.

The study showed that while about 45% of California's faults are overdue compared with the mean duration of their seismic cycle, faults in the rest of the world are early — less than 20% were overdue in each of the other regions studied, the researchers reported April 18 in the journal JGR Solid Earth.

Related: Part of the San Andreas fault may be gearing up for an earthquake

That may be an issue, Mouslopoulou said, because California's earthquake data feed into seismic forecast models for faults around the world. This means the models may be skewed by California's current outlier patterns.

She and her colleagues suggest that to better understand faults globally, researchers may use the elapsed time between the historic rupture and their next-to-last events, rather than the time elapsed since the most recent quake. This method best predicts the earthquake patterns actually seen at faults outside California, Mouslopoulou said.

One reason California is an earthquake outlier is that the San Andreas Fault and the faults around it are fast-slipping faults, meaning that they move quickly and generate earthquakes regularly. That relatively frequent earthquake recurrence means there's a good historical and geological record of quakes on those faults, Mouslopoulou said. In comparison, a slow fault that generates an earthquake every 10,000 years offers far fewer historical comparisons. Geologists will be lucky to glean even one or two earthquake records from that fault, much less to demonstrate that it's overdue for a quake.

California is currently in a quiescent period for quakes, but that likely won't last forever; there's some evidence that San Andreas quakes come in "supercycles," or clusters, Mouslopoulou said. No one knows what drives these patterns, but they may be linked to the giant subduction zone off California's coast where the Pacific Ocean floor grinds under the North American continent. Thus, in the long term, California is not likely to keep up this overdue pattern; if it ends up in a more active phase, it will probably fall closer in line with faults around the rest of the world.

The next step, Mouslopoulou said, is to compare California's fast faults to other fast-slip systems around the world, such as in Turkey's Anatolia region or the subduction zones, such as the one off the coast of Chile.

"It will be very interesting to see how these fast-moving faults and regions compare to the Californian faults," Mouslopoulou said.

Scientists have made the first direct observations of a strange seismic event that shook the world for nine consecutive days in 2023 and confirmed its cause: two "mega-tsunamis" that sloshed around an East Greenland fjord.

The gigantic waves — one of which measured 650 feet (200 meters) high, or about half the height of the Empire State Building — entered East Greenland's Dickson Fjord and rocked back and forth for nine days in September 2023, sending seismic waves reverberating through the planet's crust.

The signal was initially a mystery to scientists, but ground and satellite imagery traced the likely culprit to landslides in the fjord. These landslides unleashed the waves, known as seiches, following the climate-change-induced melting of a glacier behind the fjord. However, no direct evidence of these seiches was found.

Now, the theory has been confirmed by a new satellite that tracks water on the surface of the ocean. The findings were published Tuesday (June 3) in the journal Nature Communications.

"Climate change is giving rise to new, unseen extremes," study lead author Thomas Monahan, a graduate student in engineering science at the University of Oxford, said in a statement. "These extremes are changing the fastest in remote areas, such as the Arctic, where our ability to measure them using physical sensors is limited. This study shows how we can leverage the next generation of satellite Earth observation technologies to study these processes."

Related: 'This is a very big earthquake': The science behind Myanmar's magnitude 7.7 earthquake

Typically, scientists study the movements of tsunami waves using a method called satellite altimetry, in which radar pulses are sent to the ocean's surface from orbit to measure a wave's height based on the time it takes for the pulses to return.

But because satellites have long gaps in coverage and their instruments can only measure what's beneath them, they are unable to measure the differences in water height in confined areas like those within the fjord.

To confirm the existence of the seiches, the scientists turned to data captured by the new Surface Water and Ocean Topography (SWOT) satellite, a joint project of NASA and CNES, France's space agency. Launched in December 2022, the satellite uses an instrument called the Ka-band Radar Interferometer (KaRIn) to map 90% of the water across the ocean's surface.

KaRIn works by using two antennae mounted across a boom on each side of the satellite to triangulate the return signals of radar pulses with unprecedented accuracy — measuring water levels with a resolution of up to 8.2 feet (2.5 m) along a 30-mile (50 kilometers) arc.

SWOT data taken above the fjord during the two mega-tsunamis revealed two cross-channel slopes moving in opposite directions between it, confirming their presence. Seismic observations made thousands of miles away, alongside weather and tidal readings, further enabled the researchers to reconstruct the waves and conclusively link them to the mysterious seismic signals.

"This study is an example of how the next generation of satellite data can resolve phenomena that has remained a mystery in the past," co-author Thomas Adcock, a professor of engineering science at the University of Oxford, said in the statement.

"We will be able to get new insights into ocean extremes such as tsunamis, storm surges, and freak waves," he added. "However, to get the most out of these data we will need to innovate and use both machine learning and our knowledge of ocean physics to interpret our new results."

A video showing the ground tearing apart in a major earthquake in Myanmar in March may be the first of its kind.

The video captures a ground rupture, the ripping of Earth's crust all the way up to the surface, during a major earthquake. The magnitude 7.7 quake struck on March 28 at 12:50 p.m. local time and was felt as far away as Thailand. Nearly 5,500 people died.

The video, posted on Facebook by Singaporean engineer Htin Aung, comes from GP Energy Myanmar's Thapyawa solar farm, located near the town of Thazi, according to Aung's post. The feed is centered on a concrete-and-metal gate, which shudders and slides open as the earth begins to move. About 14 seconds into the video, a crack opens across the driveway and yard outside the gate, with the ground literally pulling apart.

"It's really kind of unsettling," said John Vidale, a seismologist at the University of Southern California Dornsife. Vidale told Live Science he knew of no other videos that show such a ground rupture. Rick Aster, a geophysicist at Colorado State University, concurred.

"To my knowledge, this is the best video we have of a throughgoing surface rupture of a very large earthquake," Aster told Live Science.

The Myanmar quake occurred on the Sagaing Fault between the Burma and Sunda tectonic plates, two minor tectonic plates. This fault slices through central Myanmar in a straight line, north to south. It's a transform fault, just like California's famous San Andreas, where the two plates move side by side against each other.

The epicenter of the Myanmar quake, where the fault rupture started, was north of the location in the video, near the city of Mandalay. This rupture then propagated both north and south, cracking the ground all along the fault line.

"The actual segment of the Earth that is slipping side to side goes from the surface down to maybe 20 or 30 kilometers [12 to 19 miles] depth," Aster said. Below that, the crust still moves, but the crust is more malleable and deforms rather than cracks.

The shaking first seen in the video comes from the earthquake waves that speed out from the rupturing crack, Vidale said. Then, the rupture itself arrives.

Seismologists get good measurements of such ruptures from seismic stations that use GPS to quantify even tiny movements of the crust. They also often do fieldwork to find evidence of ruptures after they happen, Aster said. "But we don't really understand the dynamics of what happened, exactly how things move," he said. The video might be useful for researchers who are trying to understand those unusual dynamics.

"I have no doubt that seismologists will take a very close look at this," Aster said. "It will probably lead to some kind of a publication at some point, if the location and other details can be sorted out."

Live Science reached out to Aung and to GP Energy Myanmar and will update this story with further details, if available.

A powerful magnitude 7.7 earthquake hit central Myanmar (formerly Burma) Friday (March 28), shaking Mandalay, the country's second-largest city, as well as nearby countries, including China and Thailand, the U.S. Geological Survey (USGS) reported.

The shallow earthquake struck at 12:50 p.m. local time (2:20 a.m. EDT) at a depth of about 6.2 miles (10 kilometers), the USGS reported. Just 12 minutes later, a magnitude 6.7 earthquake at the same depth shook south of the first one, and later that day, nine smaller earthquakes, ranging from magnitude 4.4 to 4.9, also hit the region.

At least 144 people were killed in the earthquakes, and 732 were injured, Myanmar's military junta said, according to The Washington Post. A monastery and multiple buildings also collapsed in Myanmar. In Bangkok, at least 10 people died when a 33-story high-rise under construction fell down; Thai authorities also said 16 people were injured and 101 were missing, the Associated Press reported.

Although Bangkok was "well removed from where the faulting was" in Myanmar, "it's a very big earthquake and it's not really surprising it would have been felt for that amount of distance," Gregory Beroza, a professor of geophysics at Stanford University, told Live Science.

The earthquakes struck at the Sagaing Fault, which runs north-south and spans nearly 1,000 miles (1,600 km) through Myanmar toward the Andaman Sea. Earthquakes that occur on this fault are known strike-slip quakes, in which one block of land moves horizontally past a block of land on the other side of the fault, according to the USGS. This is a similar setup as the San Andreas Fault in California, which is also a strike-slip fault.

Related: Scientists find hidden mechanism that could explain how earthquakes 'ignite'

Myanmar, which is just south of the Himalayas, is a seismically active region and known for its big earthquakes, Ben van der Pluijm, a professor emeritus of geology at the University of Michigan, told Live Science.

"The reason for that is that the continent of India sits on the Indian Plate. And the Indian Plate has been moving northward for around 100 million years," van der Pluijm said. "But around 40 million years ago or so, India connected with the Eurasian Plate and kept on traveling northwards into the Eurasian Plate." Over millions of years, that collision helped create the Himalayas.

Even today, the Indian Plate is still moving northward, into the Eurasian plate. That motion "is what accumulated the energy that gets released in earthquakes like today's earthquakes in Southeastern Asia," van der Pluijm said.

Today's magnitude 7.7 earthquake was so big that it wouldn't be surprising if the ground were displaced several meters horizontally, van der Pluijm added.

"This is a very big earthquake," he said. "We don't have many of these."

Because these earthquakes were so shallow, they could be compared to the magnitude 7.8 and 7.5 earthquakes that struck Turkey in 2023 and caused widespread death and damage, said Jeffrey Park, a professor of Earth and planetary sciences who specializes in earthquakes and Earth structure at Yale University.

"We should expect the same kind of damage report and also loss of life from this earthquake because it's a shallow earthquake that's in a heavily populated area of Burma," Park told Live Science.

Since 1900, the region has had six other magnitude 7 or greater big strike-slip earthquakes within about 155 miles (250 km) of today's earthquake, according to the USGS. The most recent one, a magnitude 7.0 earthquake in January 1990, caused 32 buildings to collapse. An even bigger one — a magnitude 7.9 — shook south of today's earthquake epicenter in February 1912.

Summerville, South Carolina, has been haunted by mysterious "ghost lanterns" for decades. Now, a scientist thinks she's finally worked out what the floating orbs are: Turns out, they could be linked to tiny earthquakes.

Local legends suggest the mysterious balls of light, which are often spotted near old railway tracks, are lanterns carried by the ghost of a woman who lost her husband in a train accident.

It is not clear exactly when the floating orbs were first seen in the area, but references mostly date back to the mid-20th century. The lights are described as small, glowing spheres, often in blue or green, seen floating above a narrow stretch of Sheep Island Road, where an old railway line used to run. Witnesses also reported cars shaking violently, strange whispering and, occasionally, "ghostly" apparitions.

In the surrounding area, locals have described slamming doors, the sound of footsteps, disturbed animals and birds, and objects moving as if of their own accord.

Now, Susan Hough, a seismologist for the U.S. Geological Survey (USGS), has extensively studied these reports and concluded that the mysterious orbs may be explained by a rare geological phenomenon known as earthquake lights.

Related: Scientists find hidden mechanism that could explain how earthquakes 'ignite'

According to USGS, earthquake lights are glowing spheres, sparks and streamers thought to occur in an area before, during or immediately after earthquakes.

"They have never been studied or confirmed systematically because virtually all of the data/observations are anecdotal, but lights during earthquakes have been reported for many years," Hough told Live Science in an email.

One of the most widely accepted explanations for this phenomenon is the ignition of underground gases, such as methane and radon, as they seep out of the ground during increased seismic activity. All that's needed is a spark, generated by static electricity or moving rocks.

Hough said that this explanation was particularly appropriate for the Summerville ghost. Her findings were published Jan. 22 in the journal Seismological Research Letters.

Could Summerville's ghost lanterns be caused by earthquakes?

In August 1959, a magnitude 4.4 earthquake was recorded 2.5 miles (4 kilometers) from the stretch of road where the majority of the Summerville sightings were reported. By the end of 1960, two smaller earthquakes had also been reported in the same area, Hough wrote.

It is possible that even smaller earthquakes have occurred since but were not recognized as such.

Seismic activity would also explain many of the other "paranormal" activities reported in the area, Hough writes. For example, shaking cars, swinging doors and moving objects can all be attributed to small earthquakes. Birds and animals may also get spooked by the movement, no matter how small.

As for the ignition spark, Hough said that steel rails and scrap heaps are commonly found at the sites of old railways, which when shaken may create a spark. Hough noted this would explain why similar ghost lights are often seen near disused railway lines.

While this hypothesis remains speculative, Hough said that it could be tested by measuring gas emissions from the ground in areas where the "ghosts" are seen. Sensors could also look for active faults in the region.

If confirmed, these sightings could help seismologists learn more about America's geology. "Understanding earthquakes in central and eastern North America has been challenging because we have so little data to investigate earthquakes and active faults," Hough said. "This might be the most interesting implication of my little study, that friendly ghosts are illuminating shallow faults along which gases are released."

Greek authorities have closed schools and deployed emergency crews as a swarm of earthquakes intensifies near the volcanic island of Santorini. Scientists aren't expecting Santorini or other volcanoes in the region to erupt, but they warn more powerful earthquakes could be coming.

People on Santorini began feeling tremors last week as a cluster of underwater earthquakes broke out beneath the Mediterranean's Aegean Sea. These small earthquakes — mostly magnitude 3.5 or less — continued to intensify on Monday (Feb. 3).

The largest earthquake so far was a magnitude 5, which struck 21 miles (34 kilometers) northeast of Santorini at 2:27 p.m. local time (7.27 a.m. EST), according to the University of Athens' earthquake tracking website.

The Greek authorities have responded to the earthquakes by ordering precautionary measures on Santorini and nearby islands, all of which are popular tourist destinations, the Associated Press reported.

Santorini sits on the exposed part of a largely underwater volcano called the Santorini caldera. However, researchers believe the earthquakes there are driven by the movement of plates, or plate tectonics, rather than volcanic activity.

David Pyle, a professor of Earth sciences at the University of Oxford who has studied volcanos in the Santorini caldera, told Live Science that the earthquakes by Santorini are likely caused by a series of faults — or zones where two blocks of rock move or slip against each other. However, he noted that the earthquakes were "unusual."

"The problem with this event is that we've just seen earthquake after earthquake after earthquake," Pyle said. "It's all underwater, and so it's really hard to anticipate what's going to happen next."

Related: Yellowstone National Park earthquake shakes hottest and oldest geothermal area

The Aegean Sea sits on a small plate of crust, which is stretching as the nearby African plate slides beneath the Eurasian plate. Pyle noted that stretching in the Aegean's crust creates stresses that move the faults driving the earthquakes.

This isn't the first time Santorini has experienced a series of small, concentrated earthquakes, known as an earthquake swarm. Magma moving beneath Santorini triggered a swarm around the island in 2011 and 2012, but that event was less severe than the ongoing swarm, which is northeast of the island.

"The area that is being affected is a little larger [than in 2011 and 2012,] the rate at which the detected earthquakes are occurring is also larger, and the focus of the events is outside the Santorini caldera," Pyle said.

Kolumbo volcano

Most of the earthquakes have occurred between another underwater volcano, Kolumbo, which is approximately 4.4 miles (7 kilometers) northeast of Santorini, and the small island of Anydros. While plate tectonics appear to be driving the earthquakes this time, Pyle noted that researchers are unsure whether there's a direct link between the tectonic activity and any potential volcanic activity at Kolumbo.

"We actually don't really know much about the deep systems supplying magma to the volcanos," Pyle said.

Kolumbo volcano last erupted in 1650, triggering a catastrophic tsunami that devastated islands in the region. Santorini was shaped by the earlier Minoan eruption in 1600 B.C., which was one of the largest volcanic eruptions in human history, according to Columbia University's Lamont-Doherty Earth Observatory in New York.

Small earthquakes on Santorini have raised concerns about a volcanic eruption on the Greek island.

Experts and civic leaders met at the Greek Climate Crisis and Civil Protection Ministry Wednesday (Jan. 29) to discuss the uptick in seismic activity on Santorini, an island in the Aegean Sea that curves around a flooded volcanic caldera, according to the Associated Press. The increase in seismic activity is concentrated on the caldera's northern end, they reported.

Seismic activity has gently stirred the island over the past few weeks. A seismic station on Santorini run by the Aristotle University of Thessaloniki detected at least 39 small earthquakes, mostly magnitude 3.5 or less, Friday (Jan. 31).

The island got its current shape via the Minoan eruption in 1600 B.C. — one of the largest volcanic eruptions in human history, according to the Lamont-Doherty Earth Observatory in New York. It may have inspired tales of the lost city of Atlantis, which was said to have sunk under the sea.

The volcano has experienced similar periods of unrest before without erupting. Between 2011 and 2012, there was a period of seismic activity related to magma movement below the surface, according to the Smithsonian National Museum of Natural History's Global Volcanism Program. This was preceded by a period of subsidence, or sinking, at the small island of Nea Kameni in the center of the sunken caldera.

Related: The 20 largest recorded earthquakes in history

The last time the volcano erupted was in 1950. This was a relatively small eruption, producing a lava dome and ash clouds that rose several hundred meters into the sky. An eruption in A.D. 726 reportedly caused the sea to boil and sent pumice chunks flying 250 miles (400 kilometers) away. The volcano has been causing disturbances for a long time: A 2024 study found that it erupted more than half a million years ago, ejecting a stunning 21.6 cubic miles (90 cubic kilometers) of rock and ash.

Scientists don't expect the current unrest to lead to such a dramatic outburst.

"What we must realize is that the Santorini volcano produces very large explosions every 20,000 years," Efthymios Lekkas, seismologist and head of the scientific monitoring committee for the Hellenic Volcanic Arc, said on Greece's ERT television Thursday (Jan. 30), according to the Associated Press. "It's been 3,000 years since the last explosion, so we have a very long time ahead of us before we face a big explosion."

Lekkas met with the deputy minister responsible for natural disaster recovery, the head of Greece's fire department, and local officials, according to the AP report.

A minor earthquake has hit Yellowstone National Park, shaking the hottest and oldest geothermal area in the region.

The magnitude 3.9 tremor hit near Norris Geyser Basin in Wyoming on Tuesday (Jan. 28) at 6 p.m. Mountain Standard Time (8 p.m. EST).

"The earthquake is typical of the Yellowstone region and not a sign of any significant unrest, and it was reported felt by a few people in the Yellowstone region," the U.S. Geological Survey (USGS) wrote in a Facebook post.

Scientists rate the size of earthquakes with the magnitude scale. Earthquakes with a magnitude of around 4 are minor quakes that can be felt by humans. The earthquake in Yellowstone was normal for the region, according to USGS.

Related: Scientists find hidden mechanism that could explain how earthquakes 'ignite'

Yellowstone is seismically active and experiences about 1,500 to 2,000 earthquakes each year. Most of these shakes are up to magnitude 2, but some are higher, like the one in Norris Geyser Basin on Tuesday.

Norris Geyser Basin is the hottest and oldest geothermal area in Yellowstone and home to the tallest geyser in the world, which shoots hot water and steam 300 to 400 feet (90 to 120 meters) into the air, according to the National Park Service. The basin sits at the intersection of two faults — fractures between two blocks of rock that can slip past one another and cause earthquakes.

The largest earthquake ever recorded within the park struck close to Norris Geyser Basin in 1975. That earthquake was a magnitude 6, but there was little damage and no injuries reported at the time, according to USGS's Yellowstone Volcano Observatory.

There are about half a million minor earthquakes within the 2.5 to 5.4 magnitude range every year worldwide. Those in the magnitude 6 range usually number about 100 and can cause significant damage to populated areas. Scientists consider less-common magnitude 7-range earthquakes to be major earthquakes, while the exceptionally rare magnitude 8 earthquakes — averaging about one per year or every other year — are great earthquakes, according to Michigan Technological University.

The largest recorded earthquake in U.S. history had a magnitude of 9.2. Hitting Alaska in 1964 and triggering a tsunami, this great earthquake resulted in the deaths of 128 people and about $311 million in property loss.

A period of slow, creeping movement without any shaking may be a necessary prelude to earthquakes, a new study suggests.

The research, which was on the fundamentals of how materials rupture, focused on cracks snaking through sheets of plastic in a laboratory. But the experiments revealed some basic physics of how fractures work — particularly how a buildup of friction at the interface of two bodies transforms into a sudden rupture. And those findings do apply to real-world earthquakes, said study author Jay Fineberg, a physicist at The Hebrew University of Jerusalem.

"The material composing the contacting plates will not matter," Fineberg told Live Science. "The same physical process will take place in both cases — the explosive spring of the bent plates will release in the same way."

Earthquakes form when two tectonic plates moving against one another get stuck, allowing the fault to build up stress. "The plates are increasingly stressed by the forces trying to move them, but are stuck at the brittle part of the interface that separates them," Fineberg said. This brittle section, which doesn't deform in response to stress, has a finite thickness and is what breaks during a quake.

"The fracture process doesn’t happen all at once. First, a crack needs to be created," Fineberg said. When that crack reaches the borders of the brittle interface, that crack accelerates rapidly to speeds close to the speed of sound. That's what makes the earth shake.

"The question is how does nature create the crack which then becomes an earthquake?" Fineberg.

Fineberg and his colleagues investigated the question with a mix of theoretical math and laboratory experiments. They reproduce earthquake-like fractures in the lab with blocks made of a thermoplastic called polymethyl methacrylate, better known as plexiglass. The researchers clamp sheets of plexiglass together and apply a shear, or sidelong, force, similar to those found at a strike-slip fault like Califonia's San Andreas Fault. Though the materials are different, the mechanics of the fracture are the same.

Once a crack starts, it acts like a one-dimensional line ripping through the material. Fineberg and his team had previously shown that before the crack forms, though, the material develops a kind of precursor phase called a nucleation front. These nucleation fronts — the seeds of cracks — move through the material, but much more slowly than standard cracks. It wasn't clear how this seed could rapidly transition into a fast-moving fracture.

Fineberg and his colleagues were perplexed about how this could be. With a combination of lab experiments and theoretical calculations, they realized that they needed a math update: The nucleation fronts need to be modeled in 2D, not 1D.

Instead of thinking of a crack as a line separating broken from unbroken material, Fineberg said, imagine the crack as a patch that starts within the plane where two plexi-glass "plates" meet. The energy it takes to break new material at the border of the patch is linked with the patch's perimeter: As the perimeter grows, so does the energy it takes for new material to crack.

That means the patch moves slowly and doesn't yet cause a rapid fracture that would create the seismic waves and subsequent shaking motion associated with an earthquake. While the rapid acceleration of a standard, rapid crack, releases kinetic energy into the surrounding material, the slow movement of the initial patch doesn't release any kinetic energy into its surroundings. Therefore, its movement is known as "aseismic."

Eventually, though, the patch expands outside of the brittle zone where the two plates meet. Outside this zone, the energy it takes to break new material no longer grows with the size of the broken region, and instead of a balance of energy, there is now excess energy that needs somewhere to go.

"This extra energy now causes the explosive motion of the crack," Fineberg said.

The findings, published Jan. 8 in the journal Nature, show how a slow creep before a crack can transition rapidly to an earthquake, he said. Theoretically, if one could measure aseismic movement before a rupture — on a fault line, for example, or even in a mechanical object like an airplane wing — it might be possible to predict a break before it happens. This may be complicated in real-world faults, many of which undergo aseismic creep over long periods of time without releasing any earthquakes.

Nevertheless, Fineberg and his team are now trying to detect signs of the transition from aseismic to seismic in their laboratory materials.

"In the lab, we can watch this thing unfold and we can listen to the noises that it makes," Fineberg said. "So maybe we can uncover what you can’t really do in a real fault, because you have no detailed information on what an earthquake is doing until it explodes."

Potential patches of Earth's ancient crust, sometimes called "sunken worlds," may have just been discovered deep within the mantle, thanks to a new way of mapping the inside of our planet. However, these mysterious blobs appear in places they should not, leaving researchers scratching their heads.

For decades, scientists have been building up a better picture of Earth's interior by using seismographs — 3D images created by measuring how seismic waves from earthquakes reverberate deep within our planet. This method has helped scientists identify ancient sections of the planet's crust, known as subducted slabs, that have been pulled into the mantle through subduction zones where tectonic plates meet. For example, in October 2024, researchers announced the discovery of a section of seafloor that had sunk deep into the mantle below Easter Island.

In a study published Nov. 4, 2024, in the journal Scientific Reports, researchers revealed that they had discovered "numerous" potential subducted slabs throughout Earth's mantle, using a new type of seismographic imaging. (Little information about the size, shape and exact locations of the blobs has been revealed so far.)

However, unlike previously identified subducted slabs, which are found in areas where tectonic plates currently collide or have previously smashed together, some of the new anomalies are located in places where no known tectonic activity has ever occurred, such as below the western Pacific Ocean. As a result, it is unclear how they ended up there.

"That's our dilemma," Thomas Schouten, a doctoral candidate at the ETH Zurich Geological Institute in Switzerland, said in a statement released Jan. 7. "With the new high-resolution model, we can see such anomalies everywhere in the Earth's mantle. But we don't know exactly what they are."

Related: A 'protoplanet' that created the moon may be hiding deep inside Earth

There are other potential explanations for the newly mapped blobs. For example, they may be made of crust-like material left over from the mantle's creation 4 billion years ago. Or they may consist of some other similarly dense material that has grown within the mantle over the past few hundred million years.

However, these are just alternative theories. At the moment, the identity of these blobs remains a "major mystery," ETH Zurich representatives wrote in the statement.

Finding "sunken worlds"

Until now, everything we know about Earth's innards has come from stitching together different seismographs created from different individual earthquakes across the globe. But in the new study, researchers used a new method, known as full-waveform inversion, which uses computer models to combine these seismographs into a single clear image.

This is a computationally intensive method, and to pull it off, researchers had to run the model on the Piz Daint supercomputer at the Swiss National Supercomputer Center in Lugano — formerly Europe's most powerful computer — to crunch the numbers.

Study co-author Andreas Fichtner, a seismologist at ETH Zurich who created the full-waveform model used in the new research, compared the use of full-waveform inversion to medical imaging advancements. Imagine a doctor has been studying the circulatory system for decades, Fichtner said. "Then, if you give [them] a new, better examination tool, [they] suddenly see an artery in the buttock that doesn't really belong there," Fichtner explained. "That's exactly how we feel about the new findings."

Researchers think the newly discovered blobs may be subducted slabs, largely because seismic waves travel through them both at the same speed. But this does not guarantee that they are the same thing, and more research is needed to assess whether they are actually alike.

"We have to calculate the different material parameters that could generate the observed speeds of the different wave types," Schouten said. "Essentially, we have to dive deeper into the material properties behind the wave speed."

A deadly magnitude 7.1 earthquake hit one of the holiest cities in Tibet on Tuesday morning (Jan. 7), local time.

The earthquake struck at 9:05 a.m. China standard time (8:05 p.m. EST on Jan. 6), and has killed at least 95 people and injured 130 more as of 3 p.m. local time (2 a.m. EST), according to Chinese state media.

Chinese officials reported that the earthquake had a magnitude of 6.8, but the U.S. Geological Survey (USGS) registered the magnitude at 7.1.

The earthquake's epicenter was below Dingri County in the holy city of Shigatse, or Xigazê, which is part of the autonomous region of Tibet, southwestern China.

Chinese President Xi Jinping ordered "all-out rescue efforts to save lives and minimize casualties," Chinese state media reported.

Related: Massive magnitude 7 earthquake strikes off California coast

Around 6,900 people live within 12.4 miles (20 km) of the epicenter of the latest earthquake. Initial surveys have found that more than 1,000 houses have been damaged, with some turned to rubble. Officials sent more than 1,500 firefighters and rescue workers to the affected areas on Tuesday morning, Chinese state media reported.

After the initial quake in Tibet, there were dozens of aftershocks that registered up to a magnitude 4.4. The neighbouring countries of Nepal, Bhutan and India all felt tremors, Sky News reported.

"There have already been a number of potentially damaging aftershocks and more can also be expected in the area," a spokesperson for the British Geological Survey told Live Science in an email.

The spokesperson noted that most earthquakes are followed by aftershocks, and that the rule is usually the larger the earthquake, the larger the aftershocks and the longer these aftershocks last.

"Aftershocks might affect the region for months to come which could heavily impact those living in the area, but, after a few days, the number of aftershocks expected should rapidly decrease," the spokesperson said.

Earthquakes strike when two blocks of earth slip past one another at fault lines — the zones between these blocks. Faulting events of the kind in Tibet usually cover an area that's around 28 miles (45 kilometers) long and 12 miles (20 km) wide, according to USGS.

Plate boundary

The earthquake struck at a depth of 6 miles (10 km) below the surface near the Eurasian and Indian tectonic plate boundary, according to USGS. This region has a history of large earthquakes, including the 2015 Nepal earthquake, or Gorkha earthquake, that killed some 9,000 people.

"This is a very earthquake prone region which has experienced many large earthquakes in the past, including the magnitude 7.3 Gorkha, Nepal, earthquake in 2015, which [was] around 160 km [258 miles] to the southwest and resulted in 8,669 fatalities," the spokesperson said. "In 1934, a magnitude 8.0 earthquake occurred approximately 160 km to the south-southwest."

Scientists cannot predict earthquakes, and they usually occur without warning, making them one of the most dangerous natural disasters.

The Eurasian and Indian plates colliding into one another drives a process called uplift in the Himalayas, which includes Mount Everest. The Indian plate is sliding beneath the Eurasian plate, driving the edge of the Eurasian plate up. The edges of two plates were already quite high before they started colliding millions of years ago, which contributed to the Himalayas' great height.

We finally know how a fault that gave rise to Denali, North America's highest mountain, first formed.

According to new research, the Denali Fault is actually an ancient suture mark where two land masses once joined together. Between 72 million and 56 million years ago, an oceanic plate called the Wrangellia Composite Terrane bumped into the western edge of North America and stuck there.

"Our understanding of lithospheric growth, or plate growth, along the western margin in North America is becoming clearer," Sean Regan, a geoscientist at the University of Alaska, Fairbanks and the lead author of a paper published in October in the journal Geology detailing the fault's history, said in a statement.

Massive fault

The Denali Fault is a strike-slip fault, a place where two chunks of continental crust slide past each other. On Nov. 3, 2002, the fault jolted, creating a magnitude 7.9 earthquake that knocked houseboats off their moorings more than 1,500 miles (2,414 kilometers) away in Seattle, according to an article in NASA's Earth Observatory blog.

Regan studied three sections of the fault: The Clearwater Mountains of southeastern Alaska, Kluane Lake in Canada's Yukon Territory, and the Coast Mountains near Juneau. These sites are hundreds of miles apart along the faultline. The sites are spread across about 620 miles (998 kilometers).

Research in the 1990s had suggested that despite this distance, these three fault sections were formed at the same time and place, only to be torn apart later as the two sides of the fault slid against one another. But no one had confirmed that finding.

Stitching of once-distant lands

In an attempt to do so, Regan studied a mineral called monazite at all three locations. This mineral, which is made of rare-Earth elements, changes as the rock hosting it is transformed or bent under pressure or high temperature, giving researchers a way to understand the rock's history.

“We showed that each of these three independent inverted metamorphic belts all formed at the same time under similar conditions," Regan said in the statement. "And all occupy a very similar structural setting. Not only are they the same age, they all behaved in a similar fashion. They decrease in age, structurally, downward."

This decrease in age is an effect of a phenomenon called inverted metamorphism, whereby rocks formed under high temperatures and pressures are found above rocks formed under lower temperatures and pressures — the opposite of the usual pattern, given that the deeper you go in the Earth's crust, the hotter and more pressurized it is. Inverted metamorphism is found in places where tectonic forces have warped the crust and pushed deeper rocks over shallower ones.

The findings reveal that these three regions formed at the same place and time. That place was the terminal suture zone between the North American plate and the Wrangell subplate, a mini tectonic plate that makes up part of the complex jigsaw of the northern Pacific coast.

"We’re starting to recognize those primary features involved in the stitching, or the suturing, of once-distant land masses to the North American plate," Regan said.

A magnitude 7 earthquake hit off the coast of northern California on Thursday (Dec. 5).

However, a tsunami warning that had initially been prompted by the earthquake has now been canceled, according to the U.S. Tsunami Warning System.

The earthquake hit at 10:44 a.m. PST (18:44 UTC) at a depth of about 0.4 mile (0.6 kilometers), according to the U.S. Geological Survey (USGS). The earthquake occurred off the coast, about 39 miles (63 km) northwest of the city of Petrolia in Humboldt County. It's likely that these numbers will be updated as the USGS gathers more information.

Related: The 20 largest recorded earthquakes in history

Currently, the USGS is reporting that the "landslides triggered by this earthquake are estimated to be limited in number." According to the USGS Shake Map, people reported feeling extreme shaking on the California coast by the earthquake.

Other small earthquakes, including a magnitude 4.2 and a magnitude 3.3, have also hit the area today. There are no immediate reports of damage, according to the Los Angeles Times.

Editor's note: This story was updated at 3:38 p.m. EST to note that the tsunami warning has been canceled.

Scientists are trying to establish what caused an unusual spike in earthquakes at the Mount Adams volcano in Washington state by installing multiple temporary seismic monitoring stations at the site.

In September, six small earthquakes were recorded at the "high threat" volcano. Normally, it only experiences one earthquake every two to three years, according to the U.S. Geological Survey (USGS) Cascades Volcano Observatory (CVO).

"We are now working to gather more data to assess if this is really something unusual or just a volcano talking to us a bit more than it normally does," Jon Major, the CVO scientist-in-charge, told Live Science in an email.

"Our volcanoes chatter all the time," he said, adding that the nearby Mount St. Helens and Mount Rainier often experience 10 to 20 earthquakes per month. "Some volcanoes, like St. Helens, Rainier, and Mount Hood undergo episodes of increased earthquake frequency where we see bursts of many earthquakes, which may last for days to weeks," he said. "That is all part and parcel of background activity at our Cascades volcanoes. So what we are seeing at Mount Adams is very far from unusual for the Cascades — but different for Mount Adams."

At 12,277 feet (3,742 meters) high and 18 miles (29 kilometers) wide, Mount Adams is the largest active volcano in Washington, surpassing Mount Rainier — the state's highest peak — by volume.

Related: The sea 'began to boil': Freak volcanic eruption of Santorini 1,300 years ago indicates huge blasts can occur during time of quiet

The increase in earthquake activity, including another magnitude 0.9 quake on Sunday (Oct. 6), does not indicate an eruption will take place. The earthquakes were very small, ranging from magnitudes 0.9 to 2. "Had one been standing at or near Mount Adams one would not have felt these earthquakes," Major said. The volcano last erupted around 4,000 years ago, but this relatively long period doesn't mean that an eruption is due, he added. "Every volcano has its own personality and they do not erupt on any particular cycles," he said. "Some may erupt and then be active intermittently for decades or centuries, then go back to a state of dormancy for centuries to millennia."

Mount Adams generally produces effusive eruptions, characterized by slow-moving lava flows rather than destructive, explosive eruptions. The summit has a big section of unstable and weakened rock. If an eruption were to occur, the main danger would come from lahars, or muddy flows of rock, ash and ice "that surge downstream like rapidly flowing concrete," USGS representative wrote in a statement.

Major said that generally "volcanoes will broadcast pretty loudly" if they are building toward an eruption, triggering lots of earthquakes that increase in size and frequency. The recent mild earthquake flurry doesn't fit that pattern.

The ground around the volcano will also deform as magma pushes up — something that can be ascertained with GPS and satellite monitoring — and the volcano starts to release gases. "These are the main things we watch for to give us a sense of whether or not a volcano may be building toward an eruption," Major said. "We fully expect to see these types of changes at any of our volcanoes should they begin moving toward eruption."

At present, Mount Adams only has one permanent seismic monitoring station around 7 miles (11 km) southwest of the summit. There are plans to install more permanent stations at the site next summer, Major said.

"At this point, we simply do not have enough data to say much of anything," he added. "After the new [temporary] stations we install have had a chance to collect data for a while, we'll be in a much better position to assess the potential causes and significance of this seismic activity and then determine if any further action is needed."

David Pyle, a volcanologist at the University of Oxford in the U.K., said the recent earthquakes could be caused by a "whole range of processes," including the rocks creaking due to internal stresses and strains.

"At Mount Adams the small cluster of detected events is out of the ordinary, given how quiet the volcano has been for the past 40 years," he told Live Science in an email. "This is no cause for alarm, and it is too early to diagnose the cause, but the 'sentinel seismometer' [the permanent station] has done its job, and the team monitoring the volcano will now be able to keep a closer eye on the subsurface, using the array of ground- and satellite-based instruments to which they have access."

Scientists have discovered exactly how earthquakes trigger quartz into forming large gold nuggets — finally solving a mystery that's puzzled researchers for decades.

Gold naturally forms in quartz — the second-most abundant mineral in Earth's crust after feldspar. But unlike other types of gold deposits, those found in quartz often cluster into giant nuggets. These nuggets float in the middle of what geologists call quartz veins, which are cracks in quartz-rich rocks that periodically get pumped full of hydrothermal fluids from deep within the crust.

"Gold forms in quartz all the time," said Chris Voisey, a geologist at Monash University in Australia and the lead author of a new study published Monday (Sept. 2) in the journal Nature Geoscience. "The thing that's weird is really, really large gold nugget formation. We didn't know how that worked — how you get a large volume of gold to mineralize in one discreet little place," Voisey told Live Science.

Hydrothermal fluids carry gold atoms up from the deep and flush them through quartz veins, meaning gold should theoretically become evenly spread in the cracks rather than concentrated into nuggets, Voisey said. These nuggets are exceptionally valuable and represent up to 75% of all the gold ever mined, according to the study.

Two separate clues helped Voisey and his colleagues solve the gold nugget mystery, he said. The first was that the largest nuggets occur in orogenic gold deposits, which are deposits that form during earthquakes. The second was that quartz is a piezoelectric mineral, meaning it creates its own electric charge in response to geologic stress, such as the stress generated by earthquakes.

Related: Why is gold so soft?

"When you actually put it together, it almost works out a bit too neat," Voisey said. The researchers found that earthquakes fracture rocks and force hydrothermal fluids up into the quartz veins, filling them with dissolved gold. In response to the stress of the earthquake, quartz veins simultaneously generate an electric charge that reacts with the gold, causing it to precipitate and solidify.

Gold concentrates in specific spots because "gold dissolved in solution will preferentially deposit onto pre-existing gold grains," Voisey said. "Gold is essentially acting as an electrode for further reactions by adopting the voltage generated by the nearby quartz crystals."

This means that in quartz veins, gold solidifies into clusters that grow bigger with each earthquake. The largest orogenic gold nuggets found to date weigh around 130 pounds (60 kilograms), Voisey said.

To test this idea, the researchers simulated the effect of an earthquake on quartz crystals in the laboratory. They submerged the crystals in a liquid containing gold and replicated seismic waves to generate a piezoelectric charge. The experiment confirmed that under geologic stress, quartz can produce a large enough voltage to precipitate gold out of solution.

The simulation also confirmed that gold preferentially solidifies on top of existing gold deposits in quartz veins, which helps explain the formation of large gold nuggets.

"Having pre-existing gold and having it become basically the catalyst or the lightning rod that other gold would attach to was very, very exciting," Voisey said.

One of the implications of the study is that scientists can now make large gold nuggets in the lab, "but it's not alchemy," Voisey said. "You'd have to have gold in a solution and then you just move it from basically being in a liquid to sticking to something else."

However, the results don't give geologists and exploration companies new clues as to where to mine for gold nuggets. The best science can offer for now is a device that detects piezoelectric signals from quartz at depth, Voisey said. "This can tell you where quartz veins are — but not tell you if there is gold in those quartz veins."

Lake Kivu is a giant body of water that is so saturated with carbon dioxide (CO2) and methane at its depths it could explode without warning. Two other lakes in Africa have a similarly deadly chemistry — lakes Nyos and Monoun in Cameroon — which have both exploded in the past 40 years, killing a total of nearly 1,800 people and thousands of animals.

Lake Kivu is one of the African Great Lakes that straddle a tectonic plate boundary called the East African Rift. In the rift, the Somalian tectonic plate is drifting eastward and away from the rest of the continent on the Nubian plate. (The Somalian plate is also known as the Somali plate, and the Nubian plate is also sometimes called the African plate.) This movement leads to volcanic and seismic activity in the region, which in turn funnels gases from deep inside Earth's crust to the surface — and into Lake Kivu's depths.

Related: Last Chance Lake: The unusual 'soda lake' with conditions that may have given rise to life on Earth

Lake Kivu is much bigger than either Lake Nyos or Lake Monoun, stretching 55 miles (90 kilometers) long, 30 miles (50 km) wide and up to 1,560 feet (475 meters) deep. The lake has an unusual, layered structure, with only the top 200 feet (60 m) of water mixing regularly and the lower layers remaining stagnant, Sergei Katsev, a professor of physical and geochemical limnology at the University of Minnesota Duluth, told National Geographic. This strict separation means that CO2 and methane bubbling up from the lakebed become trapped and accumulate in the bottom layer, 850 feet (260 m) deep and below, he said.

Roughly 72 cubic miles (300 cubic kilometers) of CO2 and 14 cubic miles (60 cubic km) of methane sit at the bottom of Lake Kivu, Katsev said, which is also laced with hydrogen sulfide gas from the depths of Earth's crust.

And this toxic cocktail could soon explode across the surrounding, densely populated region, Katsev said.

An explosion would release a huge cloud of gas that would hang over the lake for days to weeks and eventually dissipate into the atmosphere, Philip Morkel, an engineer and founder of Hydragas Energy, a company based in Canada that is planning to extract methane from Lake Kivu to produce electricity, told National Geographic. "When the lake reaches 100% saturation [in the bottom layer] — and it is currently somewhere over 60% — it will erupt spontaneously," Morkel said.

At that point, he said, the lake could release the equivalent of 5% of annual global greenhouse gas emissions in one day. The death toll from such an explosion would be staggering. Around 2 million people live on the shores of Lake Kivu, and "if anyone were in that cloud, it would take a minute to kill them," Morkel said.

While scientists can track how much gas is trapped in the lake, and thereby estimate the risk of an explosion, other, less predictable factors could also trigger a catastrophe. For example, an earthquake or sudden lava intrusion could shake up the lake's layers and cause an eruption, Katsev said.

The risk could also come from ongoing efforts to pump methane from the lake, Katsev said. Methane extraction began on the Rwandan side in 2016, with the goal of reducing the threat of an explosion while also supplying energy to power the country's electrical grid. But some experts warn that by disturbing the lake's structure, the operation could trigger the very explosion it is trying to prevent.

"It's a compromise of safety versus commercial exploitation in the long term," Katsev said. Extraction companies are pumping water from the bottom layer, removing methane, and returning the degassed water to the top layer. "The water generates a plume as it sinks downward," he said, heightening the risk of an explosion.

Discover more incredible places, where we highlight the fantastic history and science behind some of the most dramatic landscapes on Earth.

On 8 September 2023, a magnitude 6.8 earthquake struck western Morocco, causing damage and destruction that claimed thousands of lives in rural communities in the High Atlas Mountains. Prior to the 2023 event, the last powerful earthquake to affect Morocco occurred in 1960, and this long stretch of seismic silence may have contributed to the region and its infrastructure being underprepared for major shaking and associated damage.

Most of Morocco's seismic activity occurs near the Rif Mountains to the north of the 2023 epicenter, which are formed by convergence of the African and Eurasian plates. But closer to the High Atlas Mountains—the tallest in North Africa, with peaks rising more than 4,000 meters—the plates are converging at a rate of only about 1 millimeter per year. It's thought that mantle upwelling beneath the High Atlas, more so than the slow convergence, is a main reason why these peaks reach as high as they do.

By examining geodetic and seismic data, Huang et al. found that the 2023 Morocco quake originated in the Tizi n'Test fault system on a fault plane centered about 26 kilometers below the surface and that the rupture's strongest effects occurred at a depth of 12-36 kilometers. The event caused displacement of the Moho, the boundary about 32 kilometers beneath the surface where the crust meets the mantle.

Because of the unusual origination depth of the earthquake and its occurrence far from plate boundaries, the researchers suggest that the quake may have been triggered by the same mantle upwelling that helps lift the High Atlas Mountains, rather than by faulting activity closer to the surface.

The findings suggest that seismic hazard models should incorporate more data about deeper dynamics in intraplate regions, which are often overlooked in favor of plate boundary dynamics, according to the authors. They also highlight the importance of seismic monitoring for regions, such as this one, where slow deformation rates and complex fault structures cause infrequent but devastating disasters. (Geophysical Research Letters, https://doi.org/10.1029/2024GL109052, 2024)

This article was originally published on Eos.org. Read the original article.

Los Angeles is at risk of a major earthquake, but new research shows that the shaking from the "Big One" may not be as catastrophic as scientists initially feared. 

A new simulation of the shaking from a magnitude 7.8 earthquake on the south San Andreas fault suggests that LA may see 50% less ground motion than previously predicted. 

That could be good news for the City of Angels, but residents (and builders) shouldn't let their guard down, researchers say — there are still many questions about the damage a large quake could wreak in the region. 

"This is only one scenario," said study co-author Te-Yang Yeh, a postdoctoral researcher at San Diego State University. 

The study has not yet undergone peer review but appears on the preprint site ESS Open Archive. The study updates computer modeling first conducted during the 2008 Great Southern California ShakeOut, a project designed to quantify the consequences of a magnitude 7.8 quake on the southern San Andreas fault, which runs 30 miles (50 kilometers) east of downtown LA. 

According to the Statewide California Earthquake Center, such a worst-case quake is expected to cause 1,800 deaths, 50,000 injuries and $200 billion in damage. 

ShakeOut predicted surprisingly dramatic ground motion in downtown LA, said Thomas Heaton, a professor emeritus of geophysics and mechanical and civil engineering at Caltech, who was not involved in the new study. 

"That made quite a stir at the time, and then a number of us in the field were wondering whether or not the simulations were appropriate," Heaton told Live Science. In particular, the simulations suggested that the basins around the city – from the San Gabriel basin where Pasadena sits to the Los Angeles basin that holds its eponymous city — would act as what's called a "waveguide," funneling earthquake waves right toward the city. But basins are structurally complicated, Heaton said, so it's not clear whether they'd be such perfect channels. 

The quake simulations used in the ShakeOut project were not as detailed as today's technology allows, Yeh told Live Science. For example, the models represented the surface between the fault and LA as smooth. Yeh and Kim Olsen, a seismologist at San Diego State who co-authored the study, used a new simulation that included actual topography as well as detailed information about the geometry of the fault and the way waves travel through the subsurface. 

Their results showed a better outlook for LA. "The ground motions are still profound," Yeh said, "but it's not as horrifying as what was previously predicted."

While the basins around LA do channel earthquake waves to some extent, the researchers found, the mountainous topography around the fault also has a scattering effect. Thus, the waves going into the basins aren't as strong as previously expected, so neither are the waves coming out. 

Still, that doesn't mean Southern Californians can rest easy. 

"It's important that they actually redid this calculation, and I applaud them for that," Heaton said. "That's how good science progresses. But what is still missing in the entire analysis is real data from earthquakes." 

The area is now well-observed by a network of seismic monitors, Heaton said, but more quakes will have to occur to get those data points. 

Another consideration is that ground motion could vary a lot even within the Los Angeles area, regardless of what the whole city's average shaking looks like, said Zachary Ross, a geophysicist at Caltech who was not involved in the new research. 

The middle of the Los Angeles basin sits on sediments, Ross said, which are relatively loose and can move easily in a quake, whereas the areas closer to the mountains may have more rigid, resistant rock. There are also multiple other fault networks beside the San Andreas near Los Angeles, and they create their own hazards. 

"That's part of what makes this whole problem just so challenging," Ross told Live Science. "At the end of the day, even if you could get this one simulation fairly reasonable, it's just one of them." 

Earthquakes are one of the most mysterious and terrifying natural disasters. Although we have some idea of when the big ones might happen, others can occur seemingly out of nowhere, bulldozing cities and creating secondary disasters such as fires, landslides and tsunamis. Climate change is causing increases in other natural disasters, like wildfires and hurricanes. So could it make earthquakes more common, too? 

The biggest and most dangerous type of earthquake is the tectonic earthquake. These earthquakes occur because of tectonic plates, the massive slabs of rock that make up Earth's crust and upper mantle. Heat emanating from deep within the planet causes these plates to move an average of half an inch (1.5 centimeters) per year, making them rub up against each other. The pressure in those areas builds until it reaches a breaking point where the plates will move suddenly, releasing energy that causes earthquakes. 

Unlike with other disasters, it's almost impossible to predict when earthquakes will happen, making planned evacuations next to impossible. 

Unfortunately, climate change could make quakes happen closer together and with more intensity, experts told Live Science. With global warming, glaciers are melting at an increased rate. When melted glacier water flows off land and into the sea, the land that used to sit underneath it rises, said John Cassidy, an earthquake seismologist at the Geological Survey of Canada and the University of Victoria. 

It's the same principle as when a child pushes a pool noodle below the surface and then lets go: The noodle stays down as long as there's pressure from above, but as soon as that pressure is released, it rises back up. When this happens, pressure differences can cause faults that previously lay dormant to suddenly go off, causing earthquakes, Cassidy told Live Science. 

Related: How big is the largest possible earthquake?

More concerning than glacial-melt earthquakes are those that could be caused by an increase in sea level. As sea levels rise, pressure underwater on the seafloor also goes up, said Marco Bohnhoff, a geophysicist at GFZ Helmholtz Centre Potsdam and Free University Berlin in Germany. As water pressure spikes, the pressure on fault lines near the coast will also increase. 

"Several earthquakes are late in their seismic cycle," Bohnhoff told Live Science, including earthquakes predicted to happen near San Francisco and Los Angeles in the next few decades. "That means just a little increase in pressure is enough to advance the seismic clock. It might be enough in many places to trigger earthquakes." 

Even if we stopped using greenhouse gases now, it would take up to 1,000 years for sea level rise to stop, Bohnhoff added. He predicts that over that time, the gaps between big coastal earthquakes will become shorter.

Because proving this prediction would take centuries, Bohnhoff's research is based mostly off of existing models. For example, scientists modeled increases and decreases in the water level of the Salton Sea, an inland body of water about 80 miles (130 kilometers) northeast of San Diego, over the past 1,000 years, and found that when the lake was full, more earthquakes happened along the nearby San Andreas fault. 

Cassidy, however, is uncertain whether sea level rise would cause enough of a pressure change to make these giant quakes happen faster, at least within our lifetimes. He emphasized that when they do happen, climate change will make them more dangerous. Tsunamis triggered by earthquakes will reach farther inland as the sea level rises. Warmer oceans will lead to increased rainfall, which will raise the risk of earthquake-induced landslides. Rainfall will also make earthquake shaking more pronounced, since any vibration in wet ground is far more amplified than in dry ground. But again, we won't know exactly what will happen until it happens, and according to Cassidy there's still a lot we have to figure out.

"It's an important topic, and one that I'm sure we'll see a lot of information coming out on in the coming months and years," he said. "But no matter what we've discovered, it's not good news."

The heart of our planet has been spinning unusually slowly for the past 14 years, new research confirms. And if this mysterious trend continues, it could potentially lengthen Earth's days — though the effects would likely be imperceptible to us.

Earth's inner core is a roughly moon-size chunk of solid iron and nickel that lies more than 3,000 miles (4,800 kilometers) below our feet. It is surrounded by the outer core — a superhot layer of molten metals similar to those in the inner core — which is surrounded by a more solid sea of molten rock, known as the mantle, and the crust. Although the entire planet rotates, the inner core can spin at a slightly different speed as the mantle and crust due to the viscosity of the outer core.

Since scientists started mapping Earth's inner layers with detailed seismic activity records around 40 years ago, the inner core has rotated slightly faster than the mantle and the crust. But in a new study, published June 12 in the journal Nature, researchers found that since 2010, the inner core has been slowing down and is now rotating a bit more slowly than our planet's outer layers.

"When I first saw the seismograms that hinted at this change, I was stumped," John Vidale, a seismologist at the University of Southern California, Dornsife, said in a statement. "But when we found two dozen more observations signaling the same pattern, the result was inescapable."

If the inner core's rotation continues to decelerate, its gravitational pull could eventually cause the outer layers of our planet to spin a little more slowly, altering the length of our days the researchers wrote. 

However, any potential change would be on the order of thousandths of a second, which would be "very hard to notice," Vidale said. As a result, we would likely not have to change our clocks or calendars to adjust for this difference, especially if it were only a temporary change.

Related: 'New hidden world' discovered in Earth's inner core

This is not the first time scientists have suggested that Earth's inner core is slowing down. This phenomenon, known as "backtracking," has been debated for around a decade but has been very hard to prove.

In the new study, researchers analyzed data from more than 100 repeating earthquakes — seismic events that occur repeatedly at the same location — along a tectonic plate boundary in the South Sandwich Islands in the South Atlantic Ocean between 1991 and 2023. 

Each earthquake allowed scientists to map the core's position relative to the mantle and by comparing these measurements, the team was able to see how the inner core's rotation rate changed over time. 

The new study is the "most convincing" evidence so far that backtracking has been happening, Vidale said.

It is currently unclear why the inner core is backtracking, but it is likely caused by either "the churning of the liquid iron outer core that surrounds it" or "gravitational tugs from the dense regions of the overlying rocky mantle," the researchers wrote.

It is also unclear how frequent backtracking is. It is possible that the inner core's spin is constantly accelerating and decelerating, but these changes likely happen over decades or longer. Therefore, longer data sets are needed to infer anything about long-term trends.

The inner core remains one of the most mysterious of Earth's hidden layers. But in recent years, new technologies are allowing researchers to learn more about the inner core, including that it is slightly lopsided, that it is softer than expected, that it potentially wobbles off Earth's axis and that it has a separate innermost core.

The study authors will continue to analyze seismic data to learn more about the heart of our planet and how it changes over time.

"The dance of the inner core might be even more lively than we know," Vidale said.