CRUSTAL STRUCTURE AND MOHO DEPTH BENEATH SEVEN REGIONS IN EGYPT USING THOMSON-HASKELL (TF) AND AMMON-HERRMANN METHODS (RF)

Document Type : Original Article

Authors

1 National Research Institute of Astronomy and Geophysics, NRIAG, Helwan, Egypt.

2 National Research Institute of Astronomy and Geophysics, NRIAG, Helwan, Egypt

Abstract

Since the establishment of the Egyptian National Seismological Network (ENSN, 1997), we propose to have detailed local velocity models beneath all the recording station- sites, which are grouped into 7 regions according to the local seismicity of Egypt. The Transfer Function (TF) and Receiver Function (RF) techniques are applied to reveal the crustal and upper mantle crustal structure beneath all used station sites. The results have shown crustal structure models. We realized that Egypt has three main units.
First Unit; Upper Crustal part: it is composed of two layers; soft sediments with mean P- wave velocity 3.5 km/s and mean thickness is 2.39 km, the P- wave velocity of the second layer (Hard Deposits) is 5.01 km/sec and thickness is 6.3 km. Second Unit (middle Crustal part): It shows a mean thickness of 7.5 km and a mean P-wave velocity of 5.97 km/sec.
This part is followed by Conrad discontinuity which separates the lower crustal part from above, Third unit; lower crustal part: it exhibits a p-wave velocity of 6.86 km/sec and a thickness of 16 km. The Moho depths under the seven recognized regions are as follows: 34.8 km, 36.8 km, 32.3km, 31.50 km, 32.7 km, 33.13 km and 32.1 km, respectively with a mean Moho depth of 33.3 km.