Moment tensor inversion of small-to-moderate size local earthquakes in Egypt

Abstract

Well resolved moment tensor solutions reveal information about the sources of seismic waves. In this article, a waveform inversion technique, which uses waveform data from near-source seismic stations that belong to the Egyptian National Seismological Network (ENSN) is applied in order to estimate both focal mechanism and moment magnitude of small and moderate local earthquakes that occurred after 2010 till 2014 in and around Egypt. Fifty nine earthquakes with local magnitude (ML) ranging between 3.5 and 5.5 are analyzed. The earthquake focal mechanism obtained by waveform inversion was fundamentally validated by means of the basic technique of first onset polarities. Based on the obtained results, we identified several seismic sources in and around Egypt (i.e. Gulf of Aqaba, northern Gulf of Suez, southern Gulf of Suez-northern Red Sea, Aswan zone, Dahshour zone, and the passive continental margin). A combination of the newly estimated focal mechanisms and the previously published ones of earthquakes occurred before 2010 are used in determination of stress field for each relevant seismic source. A new scaling relationship between local magnitude (ML) and the estimated moment magnitude (Mw) has been developed using a linear regression. The results of this study may be used to improve the ENSN's stations configuration and the efficiency to record teleseismic and regional events.