摘要
2015年4月25日尼泊尔M_W7.8地震发生在喜马拉雅造山带上,人们普遍认为该地震不足以释放该造山带上累积的能量,但对该地区后续地震危险性评价多基于二维或是假三维的形变反演计算结果.本研究从2015年尼泊尔地震主震与其最大余震M_W7.3地震之间的关系出发,着重分析讨论了尼泊尔地震的时间和空间的非均匀性,结合震源机制解、地壳速度结构、精定位后的余震分布及InSAR反演结果,建立了三维发震构造模型,利用非线性摩擦有限元方法,对一个地震周期内断层摩擦行为和块体变形进行了模拟,将计算结果和地表同震形变、形变反演的同震破裂、历史地震时空演化进行对比,在确认该三维模型可靠性的基础上,讨论了该地区后续地震的可能位置,认为在1934年比哈—尼泊尔M_W^8.1地震以东区域,还存在发生大地震的可能,在最大余震M_W7.3地震东南部位,还存在发生中大地震的可能.
On April 25 th,2015,the moment magnitude（MW）7.8 Gorkha earthquake,Nepal occurred in Himalaya orogenic belt,which seems insufficient to release the accumulated energy as suggested previously.The following seismic risk assessments are mostly based on the two dimensional or pseudo-three dimensional inversions of tectonic deformation.Here we analyze the relationship between the main shock and biggest aftershock of the 2015 Gorkha earthquake sequence,and its unevenness in time and space.Combining focal mechanism solutions,crustal velocity structure,relocated aftershocks,and inversion results from InSAR,we construct a three dimensional model which changes along both the strike and dip directions of the Main Himalayan Thrust.The finite element method with nonlinear friction is used to calculate the fault behaviorand block deformation in one earthquake recurrence period.Comparison between the forward calculation results and the co-seismic deformation observed from InSAR,and co-seismic slip inverted from deformation observations,and time-space evolution of historical earthquakes revealed that the three dimension model is close to the reality.The results suggest two potential seismic risk regions in the future：a big earthquake might be located in the east of the 1934 BiharNepal MW～8.1 earthquake,and a moderate to major event might take place to the southeast of the aftershock MW7.3 earthquake.
作者
姚琪
徐锡伟
邢会林
程佳
江国焰
马未宇
刘杰
杨文
YAO Qi;XU XiWei;XING HuiLin;CHENG Jia;JIANG GuoYan;MA WeiYu;LIU Jie;YANG Wen(Chinese Earthquake Networks Center, Beijing 100045, China;Key Laboratory of Active Tectonics and Volcanos, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Earth Systems Science Computational Centre （ESSCC）, The University of Queensland, St. Lucia, QLD 4072, Australia;Faculty of Science, The Chinese University of Hong Kong, Shain, New Territories, Hong Kong 999077, China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第6期2332-2343,共12页
Chinese Journal of Geophysics
基金
中国地震局星火计划(XH16044)
国家自然科学基金(41404043)联合资助
关键词
2015尼泊尔地震
三维模型
走向不均匀
非线性摩擦
有限元方法
地震危险性
2015 Gorkha earthquake
Three dimension model
Nonuniform along the strike
Nonlinear friction
Finite element method
Seismic risk
