Geodynamic Implications for the 8 October 2005 North Pakistan Earthquake

We propose here that the 8 October 2005 North Pakistan earthquake occurred beneath the wedge-top of Balakot Formation in the Hazara-Kashmir syntaxial area. Slip occurred along the Muzaffarabad thrust, a southeast extended part of the Indus-Kohistan seismic zone. Tectonic loading of the high-density wedge/thrust sheet between the wedge-top and the descending Indian lithosphere coupled with continued flexural tectonics provoked this earthquake. The obliquely converging Indian plate along with block rotations led to development of a pinned zone around Northwestern Syntaxis of the Himalayas. Strain adjustment related to the rotational deformation processes resulted in the buckling of the more competent rock-units sandwiched between the less competent rock-units around the Hazara-Kashmir syntaxis. The western limb of the buckled unit gave rise to the development of thrusts and associated oblique slip in the inner arc of the competent rock-unit. The observations demonstrate reactivated tectonic movement along the growing fracture-tip of the buried Riasi thrust.