Analysis of the southeast Beni-Suef, northern Egypt earthquake sequence

On 11 October 1999, a moderate earthquake of local magnitude ML 4.9 hit northern Egypt. This event shook the greater Cairo region and northern part of the Nile valley and was felt in much of northern Egypt with epicentral intensity of V (EMS). It was followed by eight aftershocks with local magnitude ranging from 1.6 to 3.2. A detailed analysis of this sequence, crosscorrelation analysis, fault plane solutions and source parameter estimations is performed in the present article. A crosscorrelation analysis allowed us to recognize a number of correlated events, which were used for earthquake ancestry using a master event technique. The focal mechanism solutions for the main-shock and the largest aftershock are moderately controlled and indicate strike-slip faulting with a dip-slip normal component. Rupture directivity, aftershock distributions and isoseismal lines were combined in an attempt to determine which of the two nodal planes is the fault plane. The dynamic source parameters of the southeast Beni-Suef earthquake sequence have been estimated from the P-wave spectra of the Egyptian National Seismograph Network (ENSN). The spectral amplitude of the main shock records displayed two distinct corner frequencies that reflect a complex rupture process. The averaging of the obtained values at different stations shows that the main shock occurred on a fault length of 1.5 km with relative displacement 9 cm, stress drop of 49 bar and seismic moment of 5×1022 dyn/cm. The aftershocks show a relatively similar source parameters fault length of 0.3