Mohamed El-bohoty

In the traditional application of magnetotelluric (MT) method at a point (station), two horizontal components of the electric field (Ex and Ey) and the three orthogonal components of the magnetic field Hx, Hy and Hz are measured simultaneously as time series. The present study is a trial to test the MT method using three magnetic components measured at Misallat geomagnetic observatory (as remote magnetic reference site) instead of the three magnetic components measured at a second sounding site with the electric field components. The distance effect between the two sites has been investigated.

In the traditional application of magnetotelluric (MT) method at a point (station), two horizontal components of the electric field (Ex and Ey) and the three orthogonal components of the magnetic field Hx, Hy and Hz are measured simultaneously as time series. The present study is a trial to test the MT method using three magnetic components measured at Misallat geomagnetic observatory (as remote magnetic reference site) instead of the three magnetic components measured at a second sounding site with the electric field components. The distance effect between the two sites has been investigated.

In the present work, we present a reconnaissance study to elucidate and delin-eate the subsurface structures and tectonics of the area between Dahshour and El Fayoum province using available magnetic data; including land magnetic survey and aeromagnetic data. The study area has been selected due to its active tectonic situation. The magnetic data have been analyzed to provide new information about the tectonic setting and sub-surface structures of the study area. A detailed land magnetic survey has been carried out for the total component of geomagnetic field using two Proton magnetometers, one of them as a local reading base station placed in the middle part of the area, while the second was used for measuring the total intensity of the different points in a mesh-like configuration. The necessary corrections for the measured magnetic data have been car-ried out. The total land intensity and aeromagnetic maps have been reduced to the north magnetic pole. Moreover, wave number filter...

ABSTRACT The Fayoum–Cairo district lies in the south western part of Cairo, which is affected by several earthquakes. According to the Egyptian Network Seismology of National Research Institute of Astronomy and Geophysics (NRIAG), the last one occurred in the 31 st July, 2005 (Magnitude = 4.2 in Richter scale). Magnetotelluric (MT) method can offer good opportunity to detect crustal fluids along faults due to their high electrical conductivity anomalies. The targets of these measurements are various. Its always desired to determine the location(s) of active fault(s) to study the connection of the Fayoum–Cairo seismicity and MT resistivity structure. A single MT profile was carried out across the area in order to investigate the deep resistivity structures. Beside RTP aeromagnetic anomaly map was used to delineate the shallow structures. The area under study is located in the northern part of Egypt between latitudes 29° 40 ' N & 29° 55' N and longitudes 30° 55' E & 31° 20' E, occupying a total surface area of about 1225 km 2 (Fig. 1). The earthquake activity in Egypt is moderate (M≤6); but some events caused extremely severe damage to recent and historical constructions (Fig. 2b). The MT survey was conducted along eight stations on a northeast-southwest trending profile, selected perpendicular to the regional geologic structures and extremely for about 20 km of the study area (Fig. 2a). The Magnetotelluric method (MT) is an electromagnetic (EM) technique that is used to determine the electrical resistivity structure of the earth by measuring natural magnetic and electric fields at the surface. Two dimensional (2-D) inversions were applied to (MT) data. The reduced to the pole (RTP) aeromagnetic map compiled by the Western Digital Company (1983) has been used for determination of subsurface structures. Filtering, power spectrum and 2D-magnetic modeling were applied to the RTP aeromagnetic data.