INFLUENCE OF GLOBAL SEISMIC ACTIVITY ON IONOSPHERE AND NEAR-EARTH ATMOSPHERE PARAMETERS

Abstract

Subject and Purpose. The catastrophic magnitude of life and monetary losses associated with earthquakes spurs extensive searches for reliable earthquake precursors. It is common knowledge that lithospheric processes have a direct bearing on the state of atmosphere and ionosphere during earthquakes. However, the usual practice is to enquire things in the immediate vicinity of the hypocenter, notwithstanding the global nature of seismic processes. The present work is different as considers the changes of pressure and temperature in the near-Earth atmosphere and the total electron content (TEC) in the ionosphere for world regions at arbitrary distances from hypocenters of strong earthquakes. Methods and Methodology. Employed are the data from the maps of the ionospheric TEC and the maps of the pressure and temperature in the atmospheric surface layer in world regions of 40°N latitude. The quantitative estimates are provided by the superposed epoch analysis for winter seasons between 2012 to 2018. Days of strong earthquakes of the Richter magnitudes within 6.3 to 7.9 are taken for the "zeros" whatever the geographical coordinates of the event. Results. The near-Earth atmosphere pressure P0 shows a decrease for about 5 days before the earthquake and gets elevated for about 5 days after the event. The air temperature T behaves in the opposite way. The TEC shows a sharp increase 2 to 5 days before the earthquake. The typical deviations DP0 and DT are of up to 2 hPa and 0.3 K, respectively. The TEC deviations, DTEC, are within 3 to 4%. Where the longitudes fall on the lithosphere plate boundaries, these deviations are nearly doubled. Also, the magnitude of the effect is higher in the regions where the atmospheric pressure is lower. The established patterns indicate that the gas release from underground plays an important role in the lithosphere-atmosphere and lithosphere-ionosphere interaction effects. In this case, the main part is played by radon fluxes that initiate the near-Earth atmosphere ionization and trigger a whole chain of secon- dary processes. Conclusions. The results of the work indicate that atmospheric and ionospheric effects caused by lithospheric processes take place at arbitrary distances from strong earthquake hypocenters. Gaseous emissions from underground play an important role as a primary factor of these global effects.