Solar flares may be triggering earthquakes, controversial study claims

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.

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