Over decades of research, scientists have learned that violent earthquakes usually occur in groups, rather than randomly. Now, a new study, published July 13 in Scientific Reviews, confirms the first, although still controversial, evidence that powerful eruptions on the Sun can trigger massive earthquakes on Earth.

Strong earthquakes throughout the world are distributed unevenly, there is some correlation between them. Scientists have tested the hypothesis that solar activity can affect the occurrence of earthquakes around the world.

The sun is constantly bombarding the solar system with a huge amount of energy and particles in the form of the solar wind. Sometimes eruptions on the surface of a star cause outbursts of coronal mass or especially energy fluxes of particles – including ions and electrons – that reach Earth at breakneck speed. Already near the planet, charged particles can interfere with satellites, and in extreme conditions, turn off electrical networks. A new study suggests that particles from such powerful eruptions, in particular, positively charged ions, may be responsible for triggering groups of strong earthquakes.

Earlier, scientists also noticed the pattern of some major earthquakes on the planet: they usually occur in groups. This suggests that there may be a global phenomenon that causes these global earthquakes. And, although many researchers conducted statistical studies to try to determine the cause earlier, not a single convincing theory has yet been rigorously proven.

Researchers in the latest study examined 20-year data on earthquakes and solar activity in search of any possible correlations. In particular, the team used data from the NASA-ESA satellite for the Solar and Heliospheric Observatory (SOHO), collecting measurements of protons (positively charged particles) that come from the Sun and wash our planet.

SOHO, which is located 900,000 miles (1.45 million kilometers) from Earth, faces the Sun. This helps scientists track how much solar material ultimately hits the earth. Comparing reports of strong earthquakes with SOHO data, scientists noticed that the stronger ones occurred when the number and velocity of incoming solar protons increased. For example, when the protons emanating from the Sun reached a peak, an earthquake surge with a magnitude above 5.6 occurred over the next 24 hours.

Having noticed a correlation between the flux of solar protons and strong earthquakes, the researchers proposed a possible explanation: a mechanism called the inverse piezoelectric effect.

Previous experiments have clearly shown that the compression of quartz, a rock found in the earth’s crust, can generate an electrical impulse through a process known as the piezoelectric effect. Researchers believe that such small pulses can destabilize faults that are already close to breaking, causing earthquakes.

When the positively charged protons of the Sun crash into the Earth’s protective magnetic “bubble”, they create electromagnetic currents that propagate around the globe. The pulses created by these currents can then deform quartz in the earth’s crust, ultimately causing earthquakes.

More research is needed before scientists can prove whether the sun can cause earthquakes. But this work can help to better predict them and prepare for them, which may help save lives.