Along-strike Variations in Active Strain Accumulation in the Northwest Himalaya

Monday, 14 December 2015: 15:05
302 (Moscone South)
Kristin D Morell, University of Victoria, Victoria, BC, Canada, Talat Ahmad, Jamia Millia Islamia, Delhi, India, Mike Sandiford, University of Melbourne, Parkville, Australia, Alexandru Tiberiu Codilean, Univeristy of Wollongong, Wollongong, Australia and Reka H Fulop, University of Wollongong, School of Earth and Environmental Science, Wollongong, Australia
The spatial distribution of channel steepness, erosion rate, and physiographic data highlight pronounced along-strike changes in active strain accumulation in the northwest Himalaya. In particular, the data suggest that the mid-crustal ramp of the Main Himalayan Thrust could merge along-strike with an active portion of the Main Boundary Thrust near longitude ~77º E. This along-strike change in active fault geometry also coincides with the lateral termination of both lesser and greater Himalayan sequences, a significant reduction in total shortening within the wedge, and pronounced variations in regional seismicity. Recent activity along extensional structures in the high Himalaya of this same region appears to have led to significant reorganization, modification and capture of the Sutlej River basin, one of the largest Himalayan river systems. Given the recent 2015 Gorkha earthquake along a comparable section ~500-km along strike, these new constraints on active fault architecture could have regional implications for how strain is partitioned along seismogenic faults in the northwest Himalaya.