UTILIZATION OF OPEN SOURCE IMAGERY DATA IN DELINEATING ACTIVE FAULTS, SE WESTERN DESERT, EGYPT

The SE part of the Egyptian Western Desert is dominated by E-W and N-S striking fault sets. The ca. 300 km long Kalabsha and the ca. 100 km long Kurkur faults, are the most significant and famous faults representing these two sets, respectively. The epicenter of the November 14, 1981 earthquake (5.6 M), which was felt in Aswan and in the neighboring areas was located at the intersection between these two faults. In the present study, we test the potential of satellite imagery data freely available through the USGS website (http://earthexplorer.usgs.gov/) for mapping these faults. Resolution merge between the 1m-spatial resolution, panchromatic Orbview-3 image and the 30 m-spatial resolution Landsat 7 ETM+ multi-spectral image gives 6 multi-spectral bands in VNIR and SWIR channels with 1 m spatial resolution. PCA and high-pass filtering further enhanced rock units discrimination and hence structures. Image interpretation together with field studies of parts of these two faults indicate that they are composed of several segments having en echelon arrangement, producing releasing and constraining bends with synclines and anticlines, respectively. Both faults affect Cretaceous and Paleocene rocks. Hence they are younger than Paleocene. Open fractures filled with windblown sand in the Quaternary terraces and sand sheets were observed along and parallel to both fault traces indicating recent seismic activity. Kinematic indicators indicate a major dextral strike-slip movement and a subordinate northward dip-slip movement associated with the E-W striking Kalabsha fault and a major sinistral strike-slip movement and a subordinate eastward dip-slip movement associated with the N-S striking Kurkur fault. Paleo-stress analysis of fault plane striae of the two faults indicates sub-horizontal NNE-SSW extension. The Kurkur and Kalabsha faults, are believed here to be conjugate shear fractures. This conclusion is in agreement with the trends of the nodal planes obtained from fault plane solution of the November 14, 1981 earthquake and the events recorded afterwards. The seismicity of the area could be related to the present day plate configuration and stress distribution related to the Red Sea opening.