Looking for active faults at east Qattara depression, northwestern desert, Egypt

Abstract

Potential field methods are considered the cheapest tools in geophysical exploration to detect and characterize subsurface structures. Here we present a detailed land magnetic survey in an East Qattara Depression that was subjected before to a reflection seismic investigation. The main target of this study is infer the deeper subsurface structures and to investigate possible relations of these structures with earthquake activity. The reduced to north Pole (RTP) aeromagnetic map was used for detecting the regional extension of the interpreted structures on the land magnetic survey. The interpretations were performed on the RTP land and aeromagnetic maps using filtering techniques, least squares separations, tectonic trend analysis, spectral analysis, Werner and Euler deconvolutions, and 2.5­D modelling techniques. The results indicate that the main dominant tectonic trends are N35°Â­ 45°W, N45°Â­65°E, E­W and Aqaba trends. Moreover two seismic lines WQ85­31B and 127 were interpreted and compared with the deduced tectonic map. The results show that there is a great correlation between the location of the faults deduced from both the magnetic and seismic data. The results agree with the well logging data. Furthermore these structures correlated with the recorded earthquake activity by the National Egyptian Seismological Network (ENSN). This correlation implies that the studied area is more stable than other adjacent areas in the northern parts of Egypt close to the Mediterranean Sea and the Nile Delta River.