ESTIMATION OF MAXIMUM POSSIBLE MAGNETIDE OF EARTHQUAKE IN VARIOUS SEISMOACTIVE REGIONS BY GEOMAGNETIC DATA

Abstract

Studies have continued on the development of a method for determining the maximum possible magnitude of an earthquake (M_max) in the seismically active regions of the planet from geomagnetic data. The research is based on the empirical relationship obtained earlier for the whole planet in the form: M_max = a + b {log [abs (Z_GSM)]}, where Z_GSM is the value of the geomagnetic Z-component in the epicenter of the earthquake during the seismic event, calculated from the international reference model of the geomagnetic field (IGRF), a, b - empirical coefficients. The given ratio approximates the experimental data for the entire planet with the correlation coefficient R = 0.91, however, when calculating M_max for the Almaty seismically active region, the value of the correlation coefficient has significantly increased to R = 0.999, which is probably due to the high sensitivity of the local seismological network, allowing to determine the magnitude of current seismic events with high accuracy. In this paper, the empirical coefficients of the linear dependence between the values ​​of the geomagnetic Z component in the geocentric solar magnetosphere coordinate system and the maximum possible magnitude of the earthquake for the intra-plate seismicity in Eurasia, the San Andreas transform fault and the Sunda subduction zone were obtained. The calculations are based on data from the global seismological catalog NEIC for earthquakes with a magnitude of 4.5 or more.

Keywords: main geomagnetic field, maximum possible magnitude of earthquakes.