Earthquake Geology Along the Himalayan Frontal Thrust of India: Insight to Mechanics Earthquakes Along a Continental Convergent Plate Boundary

印度-欧亚板块边界是世界上大陆会聚的典型范例。印度和欧亚大陆之间正在进行的融合导致了全球最高的山脉和有记录以来最大的陆内地震。这些事件中最大的一次发生在沿着喜马拉雅锋面逆冲断层。喜马拉雅前缘逆冲断层沿着2500 km长的喜马拉雅弧连续伸展。喜马拉雅前缘逆冲断层沿着走向表现为相对较短且不连续的前缘陡坎，切割晚更新世和全新世河流阶地和冲积扇。该项目是与印度瓦迪亚研究所的科学家合作进行的，并得到国家科学基金会地球科学司和国际科学与工程处的支助，正在沿喜马拉雅弧沿着进行实地研究，以确定印度境内沿喜马拉雅锋面逆冲断层沿着地震破裂的时间、规模和横向范围。在沿弧长沿着的9个地点，对跨越喜马拉雅锋面逆冲断层断层陡坎的沟槽开挖所产生的暴露进行结构、地层、成壤和放射性碳研究，以便对地震过程的力学模型和沿喜马拉雅锋面沿着的大地震所造成的地震危险水平提供观测约束。由于整个印度-欧亚板块边界都在海平面以上，因此这里有可能确定沿着整个主要会聚板块边界在地震中释放的累积地壳应变的空间、时间和表面特征，以一种方式和细节不可能沿着世界海洋会聚板块边界，那里的逆冲边界在水下。拟议的研究是，应用地质技术提取印度喜马拉雅前缘逆冲断层沿着大地震发生规模和频率的信息。喜马拉雅山前缘逆冲断层是喜马拉雅山南麓的边界。正是这一断层的位移产生了历史上有记录的一些最大的大陆地震，并随着时间的推移反复发生，导致喜马拉雅山的隆起。 印度人口最稠密的地区现在沿着喜马拉雅前缘冲断层的南部边缘延伸。为了教育公众和向政府机构提供所需的信息，以便作出审慎的规划决定，减轻发生这种地震时沿沿着潜在的财务和生命损失风险，需要了解沿推力沿着大地震的规模和发生率。这项研究所获得的信息也将把观测范围的力学地震过程沿着逆冲断层，知识，然后可以应用于地震危险性分析在北美西部和其他地方周围的地球仪。

The Indian-Eurasian plate boundary is the world's type example of continental convergence. The ongoing convergence between India and Eurasia has resulted in the globes's highest mountain range and the largest recorded intracontinental earthquakes on record. The largest of these events have occurred along the Himalayan frontal thrust. The Himalayan frontal thrust extends continuously along the 2500 km length of the Himalayan arc. The Himalayan frontal thrust manifests itself along strike as relatively short and discontinuous range front scarps that cut late Pleistocene and Holocene fluvial terraces and alluvial fans. This project, carried out in collaboration with scientists from the Wadia Institute in India and supported by NSF's Division of Earth Sciences and Office of International Science and Engineering, is conducting field studies along the Himalayan arc to define the timing, size, and lateral extent of earthquake ruptures along the Himalayan frontal thrust fault in India. Structural, stratigraphic, pedogenic, and radiocarbon studies of exposures resulting from the excavation of trenches across fault scarps of the Himalayan frontal thrust fault at 9 sites along the length of the arc in order to provide observational constraints on mechanical models of the earthquake process and the level of seismic hazard imposed by large earthquakes along the Himalayan front. Because the entirety of the India-Eurasia plate boundary is above sea level, the potential exists here to define the spatial, temporal, and surficial, characteristics of accumulated crustal strain that is released in earthquakes along the entirety of a major convergent plate boundary, in a manner and detail not possible along the world's oceanic convergent plate boundaries where the thrust boundary is beneath water.The proposed research is to apply geological techniques to extract information of the size and frequency of occurrence of great earthquakes along the Himalayan frontal thrust fault of India. The Himalayan frontal thrust fault bounds the southern front of the Himalaya. It is the displacements on this fault that have produced a number of the largest continental earthquakes recorded historically and through repeated occurrence through time responsible for the uplift of the Himalaya. The most densely populated regions of India now stretch along the southern edge of the Himalayan frontal thrust. Knowledge of the size and occurrence rate of great earthquakes along the thrust is required for educating the public and providing government agencies the information needed to make prudent planning decisions to mitigate the potential financial and loss-of-life risks along the front in the event of such an earthquake. The information gained by this research will also place observational bounds on the mechanics of the earthquake process along thrust faults, knowledge that may then be applied to seismic hazard analysis in western North America and elsewhere around the globe.