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Morsy M.,National Research Institute of Astronomy and Geophysics | Hussein H.M.,National Research Institute of Astronomy and Geophysics | Hussein H.M.,North Africa Seismological Group NASG Net40 OEA ICTP | Abou Elenean K.M.,National Research Institute of Astronomy and Geophysics | And 2 more authors.
Journal of African Earth Sciences | Year: 2011

Earthquake focal mechanism solutions from 18 events in the central and northern parts of the Gulf of Suez with local magnitudes ranging from 2.8 to 5.2 and occurring between 1983 and 2004 are used to determine the type of motion and stress pattern of the region. Fault plane solutions show mostly normal component; pure normal faulting mechanisms and normal faulting with a strike-slip component. Only some mechanisms show pure strike-slip faulting. The fault planes strike in NW, WNW, NNE and ENE directions, in conformity with the geologically observed striking faults in the northern and central parts of the gulf. The principal stress orientation is also estimated by inverting the selected focal mechanism solutions. The results show that the northern part of the Gulf is subjected to NE-SW to NNE-SSW extension, with a horizontal σ(plunge 3°) and subvertical σ(plunge 80°). This means that the horizontal extensional stresses are still present in the central/northern Gulf of Suez. © 2011 Elsevier Ltd.

Elenean K.M.A.,National Research Institute of Astronomy and Geophysics | Elenean K.M.A.,North Africa Seismological Group NASG Net40 OEA ICTP | Mohamed A.M.E.,National Research Institute of Astronomy and Geophysics | Hussein H.M.,National Research Institute of Astronomy and Geophysics | Hussein H.M.,North Africa Seismological Group NASG Net40 OEA ICTP
Natural Hazards | Year: 2010

Three felt earthquakes with local magnitudes 4.0 (June 29th, 2000), 4.2 (July 07th, 2005) and 3.7 (October 30th, 2007) occurred to the southeast of Cairo along the Suez-Cairo shear zone. Being the most well recorded events by the Egyptian National Seismic Network (ENSN) in this area, they provide us an excellent opportunity to study the tectonics, the stress field, the source parameters, and the expected ground motion at Cairo. The focal mechanisms of the three events based on the first motion P-wave polarities indicate mainly normal faulting with a slight strike-slip component along nodal planes trending nearly EW and NW-SE. The three focal solutions imply a rejuvenation of the pre-existing EW and NW-SE faults due to a partly transfer of rifting deformation from the Red Sea-Gulf of Suez along these trends. Dynamic source parameters of these events are estimated from the P-wave spectra of the closest ENSN stations. The average values of the seismic moment, stress drop, rupture radius, and fault dislocation are estimated from six stations and interpreted in the context of the tectonic setting. These parameters in addition to the effects of site and path are used to synthesize the ground motion seismograms using stochastic modeling technique at the recorded stations and at some strategic sites. © Springer Science+Business Media B.V. 2009.

Aldamegh K.S.,King Abdulaziz City for Science and Technology | Hussein Moussa H.,National Research Institute of Astronomy and Geophysics | Hussein Moussa H.,Shaqra University | Hussein Moussa H.,North Africa Seismological Group NASG Net40 OEA ICTP | And 5 more authors.
Arabian Journal of Geosciences | Year: 2010

Focal mechanism solution of the 27th August 2009 earthquake (mb = 4.0) that occurred in the Badr area, northwest of Saudi Arabia, approximately 50 km from the Red Sea has been determined from the P-wave first motion polarities. Results show normal faulting mechanism with a negligible component of strike-slip motion with NE T-axis direction. This type of mechanism is common with other earthquakes of the northwestern Saudi Arabia and is considered to present the tectonic movement of the region. The dominantly extensional tectonic regime in this province demonstrates the influence of NE extension in the Red Sea. The strikes of the solution are consistent with those of the main faults near the epicenter. Hypocentral location of this earthquake was carried out using the data from the King Abdulaziz City of Science and Technology Seismic Network, Saudi Arabia, and the Egyptian National Seismological Network, Egypt. The horizontal and vertical confidence estimates are 0.5 km for both. The local magnitude, ML, following the Richter's original definition was also derived from ten digital three-component broadband seismograms. The average local magnitude determined in this study is 3.8 ± 0.17. The estimated seismic moment of this event is {Mathematical expression}. © 2010 Saudi Society for Geosciences.

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