🌍 A study links solar activity to earthquakes

The Sun, through its distant activity, could contribute to earthquakes.

A theoretical study examines this unexpected idea. It suggests that solar flares, by disrupting the ionosphere, are likely to apply localized electrical forces on fragile portions of the Earth's crust, thus potentially participating in the triggering of earthquakes.

This approach, developed by researchers from Kyoto University, outlines a physical link between space and geological depths. Solar flares indeed alter the distribution of charged particles in the upper atmosphere, a well-known phenomenon.

The proposed mechanism focuses on zones of fractured rock containing water at extreme temperatures and pressures. These damaged regions behave like electrical capacitors, connected to both the ground surface and the lower ionosphere via capacitive coupling. Consequently, the crust and ionosphere form a unified electrostatic system, rather than isolated layers.

During intense solar events, electron density in the ionosphere can increase, generating a more negative layer at low altitude. This change in atmospheric charge is not confined to high altitude. With the capacitive connection, it can generate amplified electric fields inside tiny, nanoscale cavities present in the fractured rock.

These electrostatic forces are capable of influencing crack propagation in fault zones already close to rupture. The team's calculations show that electrostatic pressure reaches levels analogous to other forces, such as tidal stresses.

Before some major earthquakes, unusual behaviors of the ionosphere have been recorded, such as higher electron density or reduced altitude. Traditionally, these signals were interpreted as consequences of stress accumulation in the crust. The recent model offers a different perspective, describing a two-way interaction where ionospheric disturbances can also feedback on subsurface processes.

Ultimately, combining high-resolution ionospheric tomography with space weather data could allow for a better understanding of the conditions that favor this electrostatic influence on the Earth's crust.