A COMPREHENSIVE THREE DIMENSIONAL CRUSTAL STRUCTURE STUDY OF -. ABU-DABBAB AREA. EASTERN DESmT. EGYPT

Abstract

The main goal of the current work is to delineate the subsurface velocity structure at Abu Dabbab area, northern Marsa-Alam city, and to study the earthquake sources by detennination of the moment tensor using the wavefonn inversion technique known as method INPAR (Sileny and Panza, 1992). The study area is characterized by moderate micro-earthquake swanns activity recorded by local telemetered mobile arrays network. Such records provide a moderate pool of arrival time data and wavefonns suitable for applying the local seismic tomography and moment tensor inversion techniques. Many studies have been done about the Abu Dabbab swanns activity. Boulus et a!., (1990) measured the heat flow value of Abu-Dabbab area at 92rn/W/m2 which is one of the highest values in the Eastern Desert of Egypt.

Ibrahim and Yokoyama (1994) studied the microearthquake swann of Abu­ Dabbab area occurred in 1993. They studied this swarm in comparison with other four swanns around the World, Vogtland, Gennany 1907-1915, Ito, Japan 1930, Matsushiro, Japan 1969-1970, and Ap-Udayn, Yemen 1992 in order to explain the main origin of Abu-Dabbab swarms, if it is igneous or volcanic. They concluded that the microearthquake swarms of Abu-Dabbab area are due to igneous activities, intrusive igneous not volcanic. Their interpretation is supported by the evidences of high heat flow, Tertiary volcanism, and many basaltic rocks in the surrounding area. On the other hand El Hady (1993) discussed the earthquake activity in the Red Sea margin and related the Abu­ Dabbab activity to geothennal evolution there. He detennined the brittle-ductile transition depth at the Abu-Dabbab area as 9-10 km by the distribution of the focal depths. Either, Badwy A., (personal communication, 2006) calculated the