Spatial Distribution of Seismicity: Relationships with Geomagnetic Z-Component in Geocentric Solar Magnetospheric Coordinate System

Abstract

For 173477 epicenters of earthquakes with М ≥ 4.5, which occurred at the globe in 1973-2010, the geomagnetic Z-component in Geocentric Solar Magnetospheric (GSM) coordinate system were evaluated for the moment of earthquake occurrence on the base of the International Geomagnetic Reference Field model (IGRF-10). It is found that in the regions, where the Z GSM reaches large positive value (low and middle latitudes), earthquake occurrence is higher than in the regions where Z GSM is mainly negative (high latitudes). In the area of strongest seismicity at the globe, which is located in the longitudinal ranges of about 120 0 E - 170 0 W, the values of Z GSM are the most high at the globe. It is found that statistically significant dependence, with correlation coefficient R = 0.91, exists between the maximal possible magnitude of earthquake (M max ) and the logarithm of absolute value of Z GSM . We suggest that earthquake occurrence is triggered by the perturbations, which in first occur at the magnetopause due to reconnection of the magnetic field of the solar wind with the Earth’s magnetic field, and then propagate into the solid earth via the GEC, which is considered at present as a main applicant for a physical mechanism of solar-terrestrial relationships. It is clear that much work remains to further verify this speculative assertion and to find the physical processes linking seismicity with the main geomagnetic field structure.