Spatio-temporal variations of seismicity and coupling in the Himalaya

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。喜马拉雅山脉的大地测量变形主要反映了从地表到大约15- 20公里深度的主喜马拉雅逆冲断层（MHT）的锁定。当地的地震监测显示，聚集的地震活动，可能是由应力积累附近的下倾边缘锁定断层带。然而，大地应变和地震活动性的分布模式显示出横向变化，这可能揭示了在大地应变和地震活动性上建立的不均匀应力。这些可能是由陆地水储存的变化，主要是在恒河平原，但其他原因也可以提倡。因此，我们提供了分析的空间格局和时间演变的大地应变和地震活动在尼泊尔喜马拉雅地区使用的数据从连续GPS（CGPS）从尼泊尔和西藏南部，和地震活动记录的尼泊尔国家地震台网。该项目的主要目标是：（1）确定喜马拉雅主冲断层（MHT）的锁定模式，（2）评估地震间应变积累与地震活动之间的关系，（3）确定应变随时间变化的原因，（4）分析地震活动性与应变率的关系，并得出地震成核的含义。应力的时间模式正在为尼泊尔喜马拉雅山未来的地震做准备。它将促进我们对物理参数的理解，这些物理参数决定断层是稳定蠕动还是具有产生重复地震滑动事件的粘滑运动。它还将促进我们对地震成核的理解，该项目将为尼泊尔和印度北方的地震危险提供重要信息。事实上，喜马拉雅地区大地震的频率主要取决于地震间隔期内滑动亏损的累积速度。此外，空间模式的赤字的滑动可能是异质性的，并可能影响大地震破裂已推断为一些subduction zones.This项目将解决最具挑战性的问题，在地震构造：为什么一个特定的断层部分蠕变或产生地震？地震活动率与震间应变积累和其他应力波动源（固体潮、雪负荷、陆地蓄水）有何关系？最后，该项目将促进国际科学合作，并将构成博士研究项目的核心。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Geodetic deformation across the Himalaya reflects primarily locking of the Main Himalayan Thrust (MHT) fault from the surface to a depth of about 15-20km. Local seismic monitoring has revealed clustered seismicity that is probably driven by stress accumulation near the downdip edge of the locked fault zone. The pattern of geodetic strain and the distribution of seismicity show however lateral variations which could reveal heterogeneous stress build up on the Also both geodetic strain and seismicity show strong seasonal variations. These may be induced by landwater storage variations, mostly in the Gangetic plain, but other causes may also be advocated. We therefore offer to analyze the spatial pattern and temporal evolution of geodetic strain and seismicity in the Nepal Himalaya using data from Continuous GPS (CGPS) from Nepal and southern Tibet, and seismicity recorded by the National Seismic Network of Nepal. The main objectives of this project are to(1) determine the pattern of locking on the Main Himalayan Thrust (MHT),(2) assess the relationship between interseismic strain build up and seismicity,(3) determine the cause of temporal changes of strain,(4) analyze the relationship between seismicity and strain rates and derive implications for earthquake nucleation.The project will help constrain the spatio-temporal pattern of stress build up that is preparing future earthquakes in the Nepal Himalaya. It will advance our understanding of the physical parameters that determine whether a fault creeps steadily or has a stick-slip motion producing repeating seismic slip events. It will also advance our understanding of earthquake nucleation.The project will contribute important information regarding seismic hazard in Nepal and northern India. Indeed, the frequency of large earthquakes in the Himalaya depends critically on the rate at which deficit of slip accumulates in the interseismic period. Also the spatial pattern of deficit of slip is probably heterogeneous and might influence large earthquake ruptures as has been inferred for a number of subduction zones.This project will address most challenging questions in seismotectonics: why does a particular fault portion creeps or produces earthquakes? How does seismicity rate relates to interseismic strain buildup and to other sources of stress fluctuations (earth tides, snow loading, landwater storage.) Finally, the project will foster international scientific collaboration and will constitute the core of a PhD research project.