Source parameters of earthquakes from the 1987 and 1993 swarms and crustal deformation study during 1987, Aswan Lake area, Egypt

Abstract

Shallow earthquake swarms of focal depths <10 km and magnitude <4 occurred beneath Aswan Lake in 1987 and 1993. The 1987 events are located along the E-W Kalabsha fault and their focal mechanism solution is strike-slip. Events of the 1993 sequence are distributed along a fault segment trending in the N-S direction and show a strike slip fault plane solution, too. Source parameters of 29 earthquakes from these two sequences are determined using a software developed by the Institute of Geophysics, Polish Academy of Science. The seismic moment and corner frequency data indicate weakness of the focal region of these swarms. The weakness may be produced by the presence of a fractured zone. Horizontal movements, which were collected by Kalabsha local geodetic network, are analyzed for epochs 1984-February 1987, February 1987-September 1987 and September 1987-November 1988. The results show different spatial patterns and magnitudes of the horizontal displacement. The large magnitude of the horizontal displacements suggests that the crustal deformation measurements are mixture of seismic and aseismic components. Moreover, correlation between the geodetic data and the stress pattern deduced from seismicity exists.