Seismotectonic analyses of Karachi Arc, Southern Kirthar Fold Belt, Pakistan

In this study geomorphological and seismotectonic analyses were carried out in Karachi arc area, southernPakistan to locate relatively safe areas from earthquakes disasters. Karachi arc is the southern extremity of the Kirtharmountain chain that occupies a major part of southern Pakistan and is comprised of a number of narrow, elongatedmountain ranges, i.e. Laki, Kirthar, Khud, Pab and Mor ranges. Based on geomorphological and seismotectonicanalyses Karachi arc area has been divided into three parts. These parts are northern, frontal and southern part. Thenorthern part of Karachi arc is seismically active where minor to moderate (3-5.9Mb) earthquakes occurred. Somebasement structures in Sehwan area seem to be still active and affected by the present-day transpressional stress field.The frontal part of Karachi arc is also active as manifested by the existence of active faults in Jhimpir, Surjan andMeting areas. These embryonic structures in the eastern part of the Arc are indicators of active deformation of Karachiarc. Presently the active deformation is taking place in frontal and northern parts of the arc, while the southern part thathas experienced deformation prior to Quaternary time is inactive and is relatively stable geoblock. The instrumental andhistoric seismicity record of the adjoining areas of Karachi arc show that the area has experienced light to moderateseismic events (4-5.9) with occasional occurrence of strong and major earthquakes. Any major or strong event in Katchrift zone, Makran subduction zone and Ornach-Nal fault zone may cause intensity of VII to VIII in Karachi arc area aswell as Karachi city of environmental seismic intensity scale 2007.