Attenuation of shallow microearthquakes at Abu Simbel area, south Egypt

摘要

In the last few years Abu Simbel area received a special attention from the Egyptian government from the tourism point of view as well as the construction of new projects, cities and cultivation of more new areas. As this area is seismically active we decided to carry out studies on attenuation of high-frequency seismic waves at this area. The quality factor (Q) of P-wave was calculated using the Spectral ratio known as the Single-Station method. A selected data set of 14 shallow seismic events recorded by a local network operated around the area was used to calculate Q_p for four stations. Magnitude of these earthquakes varied between 1.7 and 3.6. The results show variations in Q_p as a function of frequency according to the power law Q= Q_(of~n), with frequency dependence coefficient n ranging between 0.4 and 1.2. Strong azi-muthal variations of Q_p were found. It is proposed that this variation indicates presence of local strong lateral heterogeneities and/or fluid filled cracks.