Through decades of research, scientists have learned that large, powerful earthquakes commonly occur in groups, not in random patterns. But exactly why has so far remained a mystery. Now, new research, published July 13 in Scientific Reports, asserts the first strong — though still disputed — evidence that powerful eruptions on the Sun can trigger mass earthquake events on Earth.
“Large earthquakes all around the world are not evenly distributed … there is some correlation among them,” says Giuseppe De Natale, research director at the National Institute of Geophysics and Volcanology in Rome and co-author of the new study. “We have tested the hypothesis that solar activity can influence the worldwide [occurrence of earthquakes].”
A solar origin for earthquakes
To the unaided eye, the Sun might seem relatively docile. But our star is constantly bombarding the solar system with vast amounts of energy and particles in the form of the solar wind. Sometimes, however, formidable eruptions on the Sun’s surface cause coronal mass ejections, or especially energetic floods of particles — including ions and electrons — that careen through the solar system at breakneck speeds. When they reach Earth, these charged particles can interfere with satellites, and under extreme circumstances, take down power grids. The new research suggests that particles from powerful eruptions like this — specifically, the positively charged ions — might be responsible for triggering groups of strong earthquakes.
Earthquakes typically occur when rocks grind past one another as Earth’s tectonic plates shift and jostle for position. When the intense friction that’s locking plates together is overcome, the rocks break, releasing tremendous amounts of energy and shaking the ground.
But scientists have also noticed a pattern in some large earthquakes around the planet: they tend to occur in groups, not at random. This suggests there may be some global phenomenon that’s triggering these worldwide earthquake parties. And though many researchers have done statistical studies to try to determine a cause before, no compelling theories have yet been rigorously proven.
So, to tackle the lingering mystery, the researchers of this latest study combed through 20 years of data on both earthquakes and solar activity, searching for any possible correlations. Specifically, the team used data from NASA-ESA’s Solar and Heliospheric Observatory (SOHO) satellite, compiling measurements of protons (positively charged particles) that come from the Sun and wash over our planet.