Nature of Faults and Focal Mechanism Solutions of Part of Northern Pakistan
Abstract
The area extending southwards from the MMT to Kohat/Potwar plateau in Northern Pakistan is considered to be one of the most seismically active region in the world. 13 earthquake events recorded during 1984-1995 from this area have been investigated for focal mechanism solution.
Solution show strike-slip faulting with a majority (eight) indicating a left lateral sense of motion. They mostly confirm the trend and behavior of the exposed faults with exception of one which might be related with a blind fault.
Three right lateral strike-slip focal mechanism solution, one associated with the Thakot fault and other with the Kalabagh fault, support the active character of these faults or represent their buried offshoots. Two E-W trending right lateral focal mechanism solutions are considered to represent left lateral sheer at the western boundary of Indo-Pakistan Plate.
The P and T'-axis orientation indicate NE-SW direction of compression for area located north of MBT, whereas in Kohat and Potwar area mixed trend of both NE-SW and NW-SE compressive directions are obtained suggesting more complexity. In this active zone of convergence i.e., thrusting dominated region, a kinematic change due to oblique collision is inferred.
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