1. Geology Department, Faculty of Science, Minia University, 61519Minia, Egypt
2. Chair of Applied Geophysics, Montan University, 8700Leoben, Austria
3. Department of Civil Engineering, University of Bristol, BristolBS8 1TH, U.K.
4. Geology and Geophysics Department, College of Science, King Saud University, P.O. Box 2455, Riyadh11451, Saudi Arabia