GPS derived velocity and crustal strain field in the vicinity of Cairo City, Egypt

Abstract

Five years of Global Positioning System (GPS) measurements (1996-2000) are used to derive velocity vectors, strain field and principal components of strain in the vicinity of Cairo city, Egypt. Estimated horizontal velocity vectors in ITRF96 are in the range of 20-27 mm/yr with an average of 24 mm/yr in N4 degrees + or -5 degrees W. Least-Squares prediction (LSP) technique is used to estimate the dilatational strains, maximum shear strains, and principal axes of strains. The important features are: (1) dilatational strains show that the northern part of the region is under a compressive strain regime, (2) maximum shear strains show good agreement with the recent crustal activities, (3) principal axes of the strains indicate that the compressional force acting at the convergent plate boundary between the Eurasian and the African plates affect the southern part of the Nile Delta and (4) the principal axes of strains show a good correlation with the S (sub Hmax) directions obtained from earthquake focal mechanisms and bore-hole breakouts.