东喜马拉雅构造结地区地震活动及其构造意义

Seismicity in the eastern Himalayan syntaxis and its tectonic implications

东喜马拉雅构造结位于印度大陆与欧亚大陆碰撞前沿部位,其地下结构复杂,地震多发,是探索地震活动性与活动构造关系的理想场所。本研究首先对研究区构造背景、断层分布、历史大地震、近50年来的中小地震活动性及其震源机制解进行简单回顾。基于在研究区域布置的23个宽频带流动地震台的观测波形,对观测期间发生的9次较大地震进行精确定位,并对这些地震反映的构造意义进行了讨论。由于板块边界发生近90°突然偏转,导致现今的地下形变比较复杂,剪切作用伴随碰撞带挤压作用同时发生。

Eastern Himalayan syntaxis is located in the frontal area of the India and Eur-asia collision zone. I t is an ideal place to explore the relationship between the seismicity andthe tectonics because of its complexity in structure and earthquake activities. Here we re-viewed the tectonic setting, the fautt distribution, the historical large earthquakes and the small to moderate earthquakes occurred in recent 50 years. Based on the waveforms recorded by 23 temporary broadband stations we deployed,we relocate 9 earthquakes occurred in the observation time period. Then the tectonic implications are discussed. Due to the rapid rota-tion of nearly 90° at the plate boundary,the deformation is in a complex manner,combining shearing with plate collision.