摘要
收集及处理尼泊尔境内的GPS连续观测站和中国藏南地区的GPS基准站数据,获得2015年尼泊尔M_(W)7.8地震震后3 a的GPS水平形变场。结果显示,尼泊尔地震的震后形变主要分布于尼泊尔北部及中尼边境区域,且东西方向形变较小,南北方向形变较大,整体继续向南运动,最大震后位移约为10.93 cm。采用孔隙弹性回弹模型计算的理论地表位移远小于GPS观测值,无法解释GPS观测到的震后形变。采用震后余滑模型反演的结果表明,震后余滑主要集中在断层的下倾延伸部分,且空间分布较广,余滑释放的地震矩为1.09×10^(20)Nm。采用PSGRN/PSCMP程序计算粘弹性引起的理论地表形变结果显示,粘弹性松弛模型不能解释近场GPS观测值,但在远场区域的运动方向与GPS观测值一致。采用粘弹性松弛和震后余滑组合机制模型进行反演,余滑释放的地震矩降为1.08×10^(20)Nm,且空间分布更加集中。研究结果表明,组合机制模型在保证了模型拟合精度的基础上,反演结果与应力驱动模型反演结果更接近。
By collecting and processing the data of GPS continuous observation stations in Nepal and GPS reference stations in southern Tibet of China,we obtain the GPS horizontal deformation field three years after the 2015 M_(W)7.8 earthquake in Nepal,which shows that the post-earthquake deformation is mainly distributed in the northern part of Nepal and the border area between China and Nepal,and that deformation in the east-west direction is small,while deformation in the north-south direction is large.The whole earthquake continues to move south,and the maximum post-earthquake displacement is about 10.93 cm.The theoretical surface displacement calculated by the pore elastic rebound model is far less than the GPS observation value,which cannot explain the post-earthquake deformation observed by GPS.The post-earthquake residual slip distribution inversed by the post-earthquake residual slip model shows that the post-earthquake residual slip is mainly concentrated in the downdip extension part of the fault,and the spatial distribution is wide.The seismic moment released by the residual slip is 1.09×10^(20)Nm.The theoretical surface deformation caused by viscoelasticity in the forward modeling of PSGRN/PSCMP shows that the viscoelasticity relaxation model cannot explain near-field GPS observations,but its movement direction is consistent with the GPS observations in the far-field region.After inversion using the combined mechanism model of viscoelastic relaxation and post-earthquake residual slip,the seismic moment released by residual slip is reduced to 1.08×10^(20)Nm,and the spatial distribution is more concentrated.The results show that the inversion results of the combined mechanism model are closer to those of the stress driven model on the basis of ensuring the fitting accuracy of the model.
作者
姚未正
徐克科
朱绪林
邵振华
YAO Weizheng;XU Keke;ZHU Xulin;SHAO Zhenhua(School of Surveying and Land Information Engineering,Henan Polytechnic University,2001 Shiji Road,Jiaozuo 454003,China)
出处
《大地测量与地球动力学》
CSCD
北大核心
2021年第8期833-840,共8页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金(41774041)
河南省高等学校青年骨干教师培养计划(2016GGJS-041)
中国博士后科学基金(2017M610954)
河南理工大学博士基金(B2017-15)。
关键词
尼泊尔地震
震后形变
震后余滑
粘弹性松弛
Nepal earthquake
post-seismic deformation
afterslip
viscoelastic relaxation
