Five years of Global Positing System (GPS) measurements, during 1996–2000, were used to derive velocity vectors and principal components of strains in and around Cairo city, Egypt. Estimated horizontal velocity vectors in ITRF96 are in the range of 20-27 mm/yr with an average of 24.16 mm/yr in N4 o 5 o W. We employed the Least-Squares prediction (LSP) technique to segregate the signal and noise in the data. Estimated signals were used to reconstruct the strains; dilatations, maximum shear strains, and principal axes of strains. Obtained strains are portrayed active tectonic environments in and around the Cairo city; (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, and (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. Moreover, the principal axes of strains show a good correlation with the S Hmax directions obtained from earthquake focal mechanisms and borehole breakouts. |
