Monitoring the Processes of Interseismic Accumulation and Coseismic Release of Stresses in the Medium Nearby Earthquake Sources Based on the Analysis of Tidal Response of the Earth’s Surface

Abstract

Abstract—The Global Seismographic Network (GSN) incorporating more than 150 seismic stations all over the world allows recording not only high-frequency seismic signals but also the response of the medium to semidiurnal and diurnal tidal impact. The correlation method for the analysis of GSN data developed by us makes it possible to detect variations in the amplitudes of tidal response associated with elastic moduli of the medium with an accuracy of 0.5%. The processes of stress accumulation and fracturing in the zone of a tectonic fault can significantly affect elastic properties of the medium which, in turn, may cause changes in tidal response of the medium in the vicinity of the earthquake’s source. In this work, a linear dependence is detected between the change in the amplitude of tidal response at GSN stations and the magnitude of the coseismic stress change in the medium in the vicinity of the station estimated from GPS data. The developed method for the analysis of tidal tilts can be used for studying the processes of accumulation and redistribution of tectonic stresses before the strong earthquakes in seismically active regions.