Towards a data-based and physics-based model of interseismic and seismic behavior of Main Himalayan Thrust

California Institute Of Technology, Pasadena CA

Investigators

Abstract

The Himalaya stands out as the major threat with respect to seismic hazard in central Asia where it puts at risk the dense population and economies of several countries. The project will contribute important information regarding seismic activity in that area and, more generally, will advance methods regarding the use of geodetic measurements in seismic hazard studies. Recent and historical earthquakes in the Himalaya fall way short of balancing the rate at which interseismic strain is currently accumulating in the Himalaya. Thus we have a very incomplete view of how interseismic strain is released by transient seismic, and possibly, aseismic slip on the Main Himalayan Thrust fault. The long term objective of this project is the development of a dynamic model and the acquisition of appropriate data to validate and calibrate the model that will allow assessing the full range of possible earthquake scenarios in the Himalaya and their probability of occurrence. To achieve that goal we propose (1) to keep on monitoring and improve the modeling of interseismic coupling on the MHT, (2) use dynamic modeling to evaluate the fault frictional properties needed to account for the observed pattern of interseismic coupling, the sensitivity of seismicity to secular and seasonal stress build up an (3) use dynamic models to test how the statistics of small earthquakes triggered by stress build up at downdip edge of the locked portion of the MHT can be used to constrain the statistics of the very large events rupturing the whole locked zone (4) constrain the viscous properties of the crust based on the geodetically measured deformation induced by surface load variations measured from the GRACE gravimetric satellite mission.