Source parameters and moment tensor inversion of April 11, 2020 (mb=4.4), the significant El-Negalah Earthquake, Matrouh, Egypt

Abstract

ABSTRACT A moderate size felt earthquake with a body wave magnitude (mb = 4.4) shocked the western part of northern Egypt on 11 April 2020. The nature of this seismic source has yet to be fully understood. This paper presents an analysis of the seismic source of this significant earthquake. A robust hypocentral parameters estimation is performed by collecting the data from 29 seismic stations in the Eastern Mediterranean region to reduce the azimuthal gap within the available location. The full-waveform Moment Tensor Inversion (MTI) is applied to derive the faulting mechanism of the quake. The obtained solutions indicate a reverse faulting mechanism. The plausibility of the obtained mechanism is analysed in terms of measuring the Kegan angle and evaluating the stability of the resulting mechanism. The source parameters are estimated using the S-wave amplitude displacement spectra. The obtained source parameters indicate that the seismic moment (Mo) is 8.9 × 1015 Nm, the fault radius L is 1013 m, the stress drop (σ) is 3.8 MPa, and the displacement (d) is 0.053 m. The analysis of this seismic source is of fundamental importance for evaluating seismic hazard in northern Egypt, particularly for critical facilities and safe hydrocarbon exploration.