Normal faulting mechanisms in the Western Desert of Egypt |
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| Authors: | Ali K Abdel-Fattah Ahmed Badawy K Y Kim |
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| Institution: | (1) National Research Institute of Astronomy and Geophysics, Cairo, Helwan, 11421, Egypt;(2) Kangwon National University, 192-1 Hyoja-2-dong, Chunchon, Kangwon-do, 200-701, South Korea |
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| Abstract: | Egypt is recognized as a moderate seismicity region where earthquakes are distributed within several active regions. Owing
to sparse distribution of both seismicity and seismic stations, mostly moderate-size Egyptian earthquakes were recorded by
regional stations. One of such cases is the moderate-size earthquakes of moment magnitudes greater than 4.0 which struck the
Western Desert of Egypt in 1998 and 1999. These events are the first instrumentally recorded earthquakes occurring in the
area. In the present study, the source mechanism for these earthquakes was estimated using the waveform data recorded from
one of the very broadband MedNet seismograph stations and polarities from the national short-period seismographs. An iterative
technique was applied to find the best-fit double-couple mechanism by a grid search over strike, dip and rake. Regional synthetic
seismograms were calculated by using f–k integration in the frequency range of 0.03–0.1 Hz. A crustal structure fitted to surface wave dispersion curves was used
to compute Green’s function. Focal depths were determined through the grid search method for a range of source depths. Our
results show a normal faulting mechanism with minor strike-slip component. The NNW trend has been chosen as a preferred rupture
plane in consistence with surface and subsurface faults and microearthquake seismicity in the epicenteral area as well. |
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| Keywords: | grid search method moment magnitude relocation seismic moment source mechanism Western Desert Egypt |
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