Japan earthquake & tsunami of 2011: Facts and information

An aerial view of damage to Sukuiso, Japan, a week after the earthquake and subsequent tsunami devastated the area in March, 2011. Also this isn't likely to happen on the East Coast, it's not inconceivable. — This isn't likely to happen on the East Coast, but it could. This is an aerial view of damage to Sukuiso, Japan, a week after the earthquake and subsequent tsunami devastated the area in March, 2011.

(Image credit: Dylan McCord. U.S. Navy)

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A surprise disaster
The 2011 Tohoku earthquake
Early warning
Death toll of the 2011 earthquake and tsunami
The Fukushima nuclear meltdown
The response
Worldwide effects
Amazing facts
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The Japan earthquake and tsunami of 2011, also known as the 2011 Tohoku earthquake and tsunami or the Great Tohoku earthquake, was a natural disaster that shook northeastern Japan on March 11, 2011. The disaster began when a magnitude-9 earthquake shook the region in the early afternoon, unleashing a savage tsunami.

The effects of the great earthquake, which was the strongest in Japan's recorded history, were felt around the world, from Norway's fjords to Antarctica's ice sheet. Tsunami debris has continued to wash up on North American beaches years later.

More than 120,000 buildings were destroyed, 278,000 were half-destroyed and 726,000 were partially destroyed, according to the agency. The direct financial damage from the disaster is estimated to be about $199 billion dollars (about 16.9 trillion yen), according to the Japanese government. The total economic cost could reach up to $235 billion, the World Bank estimated, making it the costliest natural disaster in world history.

The unexpected disaster was neither the largest nor the deadliest earthquake and tsunami to strike this century. That record goes to the 2004 Banda Aceh earthquake and tsunami in Sumatra, a magnitude-9.1, which killed more than 230,000 people. But Japan's one-two punch proved especially devastating for the earthquake-savvy country, because few scientists had predicted the country would experience such a large earthquake and tsunami.

Japan's scientists had forecast a smaller earthquake would strike the northern region of Honshu, the country's main island. Nor did they expect such a large tsunami. But there had been hints of the disaster to come. The areas flooded in 2011 closely matched those of a tsunami that hit Sendai in A.D. 869. In the decade before the 2011 Tohoku earthquake, a handful of Japanese geologists had begun to recognize that a large earthquake and tsunami had struck the northern Honshu region in that year. However, their warnings went unheeded by officials responsible for the country's earthquake hazard assessments, Live Science previously reported. Now, tsunami experts from around the world have been asked to assess the history of past tsunamis in Japan, to better predict the country's future earthquake risk.

The 2011 Tohoku earthquake struck offshore of Japan, along a subduction zone where two of Earth's tectonic plates collide. In a subduction zone, one plate slides beneath another into the mantle, the hotter layer beneath the crust. The great plates are rough and stick together, building up energy that is released as earthquakes. East of Japan, the Pacific plate dives beneath the overriding Eurasian plate. The temblor completely released centuries of built up stress between the two tectonic plates, a recent study found.

Residents of Tokyo received a minute of warning before the strong shaking hit the city, thanks to Japan's earthquake early warning system. The country's stringent seismic building codes and early warning system prevented many deaths from the earthquake, by stopping high-speed trains and factory assembly lines. People in Japan also received texted alerts of the earthquake and tsunami warnings on their cellphones.

Less than an hour after the earthquake, the first of many tsunami waves hit Japan's coastline. The tsunami waves reached run-up heights (how far the wave surges inland above sea level) of up to 128 feet (39 meters) at Miyako city and traveled inland as far as 6 miles (10 km) in Sendai. The tsunami flooded an estimated area of approximately 217 square miles (561 square kilometers) in Japan, according to the National Oceanic and Atmospheric Administration .

In the tsunami's aftermath, Japan's Meteorological Agency was criticized for issuing an initial tsunami warning that underestimated the size of the wave. In some regions, such as Miyagi and Fukushima, only 58% of people headed for higher ground immediately after the earthquake, according to a Japanese government study published in August 2011. Many people also underestimated their personal risk, or assumed the tsunami would be as small as ones they had previously experienced, the study found.

Scientists from around the world descended on Japan following the earthquake and tsunami. Researchers sailed offshore and dropped sensors along the fault line to measure the forces that caused the earthquake. Teams studied the tsunami deposits to better understand ancient sediment records of the deadly waves. Earthquake engineers examined the damage, looking for ways to build buildings more resistant to quakes and tsunamis.

The surge of water carried an estimated 5 million tons of debris out to sea, the National Oceanic and Atmospheric Agency reported. Japanese docks and ships, and countless household items, have arrived on U.S. and Canadian shores in the ensuing years. The U.S. Coast Guard fired on and sank the derelict boat 164-foot Ryou-Un Maru in 2012 in the Gulf of Alaska. The ship started its journey in Hokkaido.

The earthquake shifted Earth on its axis of rotation by redistributing mass, like putting a dent in a spinning top. The temblor also shortened the length of a day by about a microsecond.
More than 5,000 aftershocks hit Japan in the year after the earthquake, the largest a magnitude 7.9.
About 250 miles (400 km) of Japan's northern Honshu coastline dropped by 2 feet (0.6 meters), according to the U.S. Geological Survey.
The jolt moved Japan's main island of Honshu eastward by 8 feet (2.4 m).
The Pacific Plate slid westward near the epicenter by 79 feet (24 m).
In Antarctica, the seismic waves from the earthquake sped up the Whillans Ice Stream, jolting it by about 1.5 feet (0.5 m).
The tsunami broke icebergs off the Sulzberger Ice Shelf in Antarctica.
As the tsunami crossed the Pacific Ocean, a 5-foot high (1.5 m) high wave killed more than 110,000 nesting seabirds at the Midway Atoll National Wildlife Refuge.
In Norway, water in fjords pointing toward Japan sloshed back and forth as seismic waves from the earthquake raced through.
The earthquake produced a low-frequency rumble called infrasound, which traveled into space and was detected by the Goce satellite.
Buildings destroyed by the tsunami released thousands of tons of ozone-destroying chemicals and greenhouse gases into the air.

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Becky Oskin covers Earth science, climate change and space, as well as general science topics. Becky was a science reporter at Live Science and The Pasadena Star-News; she has freelanced for New Scientist and the American Institute of Physics. She earned a master's degree in geology from Caltech, a bachelor's degree from Washington State University, and a graduate certificate in science writing from the University of California, Santa Cruz.

A surprise disaster

The 2011 Tohoku earthquake

Early warning

Death toll of the 2011 earthquake and tsunami

The Fukushima nuclear meltdown

The response

Worldwide effects

Amazing facts

Additional resources

Bibliography