f Geodynamical Studies in Cairo Region Deduced from Graviyt and Geodetic Data

Great Cairo region is considered as a very important part in Egypt. Big earthquake with a magnitude of Mb=5.8 on October 1992,occurred at Dahshour area, 35 Km south west of Cairo ,so different geophysical and geodetic investigations were carried out in and around this vital area of Egypt. At the present work, monitoring and analysis of the crustal movements using the Global Positioning System (GPS) and repeated micro gravity measurements are performed on the geodetic points distributed around the Great Cairo. The investigated area lies in transitional stress regime with a tension axis about NS to NE - SW. There faults trends E-W, NW - SE, and NE - SW, affect the area and all of these faults are normal. The horizontal movements obtained from analysis of GPS measurements were 8 mm / year. Preliminary results of the geophysical analysis of time variations in the gravity field of non-tidal type obtained within the limits of the Great Cairo geodetic test site, as well as the relationship between those variations and earthquakes are discussed.