Seismotectonic and seismological aspects of the Mostaganem (Western Algeria) May 22, 2014 (Mw 4.9) seismic event

Abstract

On Thursday, 22 of May 2014, at 6 h 22 min 0.3.3 s (GMT + 1) a moderate-sized earthquake struck the Mostaganem, Western Algeria, region. The main shock, recorded by many international and national seismological stations, was preceded by a foreshock, 3 hours before, on May 22, 2014 (Ml = 4.1) at 3 h 57 min 41.4 s and followed by four well-felt aftershocks (M > 3.0) that lasted about 1 year. The main shock did not cause loss of lives but serious panic among the population was reported. The main shock, however, caused cracks in walls and roofs, sometimes destroyed, the old non-engineered and precarious adobe dweller corresponding to I0 = VI–VII (Msk scale). We used accelerograph records to (i) determine the epicenter location (longitude = 0.3537 E, latitude = 35.8598 N, (ii) perform waveforms inversion to calculate the earthquake parameters. The obtained results are, respectively, the seismic moment (M0) = 2.71 E + 16, the Mw = 4.9 and the focal depth = 6 km. The obtained focal mechanism solution shows reverse faulting with small right lateral component with the following nodal plans: NP1, strike = 193.5, dip = 49.5, slip = 57.6 and NP2, strike = 57.8, dip = 50, slip = 122.1. On the other hand, the seismotectonic framework of the Dahra area exhibits a serie of NE-SW trending “en echelon” faulted folds that may be active as suggested by this study.