PHYSICAL MODEL AND NUMERICAL ESTIMATES OF TELLURIC CURRENTS GENERATED BY X-RAY RADIATION OF A SOLAR FLARE

Current studies of solar-terrestrial relationships and the possible impact of space weather on seismic activity are based on statistical analysis without detailed consideration of possible physical mechanisms that results in unclear or contradictory conclusions. It is proposed to consider the hypothesis of electromagnetic triggering of earthquakes by a sharp burst of telluric currents in the lithosphere, including seismogenic crust faults, due to interaction of X-ray radiation of a solar flare with the «ionosphere- atmosphere-lithosphere» system. This hypothesis is based on the field and laboratory experiments carried out in Russia over the past forty years that convincingly demonstrated a possibility of triggering of earthquakes by injection of electric current into the crust faults. A mathematical model and a computer code for numerical estimates of telluric currents generated by solar flare radiation are presented. The numerical estimates performed show that solar flares can generate telluric currents in the conducting layers of the Earth's crust with a density comparable to the densities of currents generated in the crust by artificial pulsed power sources capable to trigger earthquakes. Consequently, the triggering of seismic events is possible not only by artificial sources of electric current, but also by ionospheric disturbances caused by strong solar flares. This model can be used to assess the seismic hazard during the period of strong variations in space weather parameters, in particular, pulsed changes in the geomagnetic field caused by strong solar flares of X-class.