Delineation the active subsurface structures at Fayoum-Cairo district, Egypt, using magnetic and magnetotelluric tools

摘要

In this work, we present a reconnaissance study to elucidate and delineate subsurface fault structures for an active tectonics area that lies between Cairo and El Fayoum provinces and consider major sources of seismicity in Egypt. Well logging, aeromagnetic, land magnetic, and magnetotelluric data have been used. The well-logging data were used for several drilled wells along W-E direction. The magnetic data were analyzed using trend analysis, 3D magnetic modeling, and Werner deconvolution techniques. The magnetotelluric data were interpreted using 2D (TM-TE) modeling techniques. The results show that there are eight major fault structures having E-W, N-S, and NW-SE directions. These faults extend downward for about 20 km at the Dahshour and Qatrani areas. The epicenter sources of the earthquakes are clustering around the intersections of these structures. The Kattaniya horst structure has been interpreted as a regional structure that exceeds the limits previously determined by geologists. The depth to this horst reaches about 1.8 km at the NW and more than 4.3 km at the southern parts. The interpreted values of magnetic susceptibility at the horst zone indicate that they are ultrabasic/basic intrusion bodies.