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

喜马拉雅山是中亚地震灾害的主要威胁，它使一些国家的人口密集和经济面临危险。该项目将提供关于该地区地震活动的重要信息，更广泛地说，将促进在地震危险研究中使用大地测量的方法，喜马拉雅最近和历史上的地震远远没有达到喜马拉雅目前地震间应变积累的速度。因此，我们对地震间应变是如何通过瞬变地震释放的，以及喜马拉雅主逆冲断层上的可能的无震滑动，有一个非常不完整的看法。该项目的长期目标是开发一个动态模型，并获取适当的数据，以验证和校准该模型，从而能够评估喜马拉雅山可能发生的各种地震情景及其发生概率。为了实现这一目标，我们建议（1）继续监测和改进MHT上的地震间耦合模型，（2）使用动态模型来评估断层摩擦特性，以解释观测到的地震间耦合模式，地震活动性对长期应力和季节应力敏感性增加，使用动力学模型来测试MHT锁定部分下倾边缘的应力积累所触发的小地震的统计数据如何能够用于约束破坏整个锁定区的特大事件的统计数据（4）根据GRACE重力卫星使命测量的表面载荷变化引起的大地测量变形，限制地壳的粘性特性。

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.