Distribution of magnetogravity waves during strong earthquakes (M > 6.5) preparation periods

Abstract

Magnetogravity activity during the preparation of four strong (M > 6.5) earthquake with epicenters at medium (35–40° N) and low (10° S–10° N) latitudes is detected. For this purpose a comparison of simultaneous disturbances at dynamic spectra of ionospheric layers Es, E, F2 critical frequencies and geomagnetic field X, Y, Z components was performed. It was found that the greatest number of magnetogravity events noted in epicenters vicinity takes place at two days before the considered earthquakes. Evaluation of dynamic spectra intensity level which was obtained by data from magnetic stations located around the epicenter, allows to identify the magnetogravity waves (MGW) propagation direction with least damping. In most cases they coincide with geomagnetic field direction. Attention is paid to ionospheric wind influence for low-frequency MGW mode.