Preliminary geodetic constraints on plate boundary deformation on the western edge of the Indian plate from TriGGnet (Tri-University GPS Geodesy Network)

Abstract

Shortly after the 2005 Kashmir earthquake, scientists from three Pakistan Universities collaborated with US, and through them, Indian scientists to monitor seismotectonic deformation and crustal velocities on the western edge of the Indian plate. Twelve GPS receivers were installed at key locations in Pakistan, with some sites monitored continuously and others for a week once each year. More than 80 points have been measured with various periods of longevity. We report here the initial results of these surveys using the Indian pate as a fixed frame of reference. Following are the main results of our study: 1) Sindh province and the southern Punjab are deforming insignificantly (linear strain rates 0.01 µstrain per year) 2) the Makran coast is moving rapidly (18 mm yr^-1) southward indicating a locked offshore region; 3) post-seismic effects of 2005 Kashmir earthquake are largely ceased by 2009; 4) interseismic convergence of the Karakorum ranges (>16 mm yr^-1) is reduced to 5-8 mm about a line from Peshawar through Islamabad to Srinagar indicating significant strain to have focused in the ranges to the north;  5) the Potwar plateau is moving at less than 3 mm SSE, a factor of four slower than to its geologically estimated rate of 13±2 mm yr^-1; and 6) the geodetic rupture parameters of the 2005 Kashmir, and the October 2008 Pishin Baluchistan earthquakes.