摘要
2015年4月25日发生在尼泊尔博克拉M_S8.1大地震的深层动力过程与"地中海—喜马拉雅—南亚地震带"的中段喜马拉雅地震活动带密切相关.这次大地震是该地震强烈活动带上长期以来深部物质与能量强烈交换、运动,并导致构造活动和应力积累的产物.综合分析与研究提出:(1)博克拉M_S8.1大地震的孕育、发生和发展具有长期活动和近年来相邻地带地震活动频繁的背景;这一地带自1505年—2015年,即500多年来相继发生多次M_S≥8.0的大地震.(2)这一地带具有特异的地球物理边界场响应和深层动力过程,显示深部物质的重新分异、调整与能量交换.(3)大地震发生与周边地带应力场分布特异,壳、幔结构与介质属性变异及破裂响应与断层面解的属性相关.(4)喜马拉雅地带的三条北倾断裂带以不同角度向深部延伸、震源位置及浅表层的变形特征尚应深化理解.(5)M_S8.1大地震的发生对相邻地带的波场影响强烈,故应强化高精度地球物理场的观测和探测,以"捕捉"未来可能大地震的孕育与发生.
Deep processes of the Ms8.1 earthquake on April 25, 2015 located in Pokhara, Nepal is closely related to Himalayan seismically active area which is the middle part of ＂Mediterranean- Himalaya-South Asia seismic zone＂. This huge event is the result of long-term tectonic activity and accumulation of stresses in this intense activity area which is due to the strong deep material movement and severe energy exchange. Our comprehensive analysis and study suggest that （1） The generation, occurrence and development of this great earthquake has a frequently seismic activity background both in its locality and adjacent regions; There have been several megaseisms （Ms≥8.0） in 500 years from 1505 to 2015. （2） The specific geophysical boundary conditions and deep dynamic processes in this area show deep material redifferentiation and energy exchange. （3） The occurrence of the megaseism is related to peculiar stress distribution of the surrounding areas, special crust-mantle structure, differentiation of media attributes and rupture responses, as well as properties of fault plane solutions. （4） There are still some aspects which need to deepen understandings including three north-trending faults with different angles towards to depth in the Himalaya, the hypocentral locations and shallow surface deformation features. （5） The Ms8.1 earthquake has strong influences on the wave field of its adjacent regions, so we should strengthen the observation and detection of geophysical fields to capture the generation and occurrence of possible great earthquakes in the future.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第1期123-141,共19页
Chinese Journal of Geophysics
基金
国家自然科学基金项目(90914012
41674102)资助
