李宇磊, 张永志, 王帅, 刘泰. 2015年尼泊尔Mw7.8地震的震后形变机制—震后余滑效应和黏滞性松弛效应[J]. 武汉大学学报 ( 信息科学版), 2020, 45(10): 1578-1587. DOI: 10.13203/j.whugis20180349
引用本文: 李宇磊, 张永志, 王帅, 刘泰. 2015年尼泊尔Mw7.8地震的震后形变机制—震后余滑效应和黏滞性松弛效应[J]. 武汉大学学报 ( 信息科学版), 2020, 45(10): 1578-1587. DOI: 10.13203/j.whugis20180349
LI Yulei, ZHANG Yongzhi, WANG Shuai, LIU Tai. Post-Seismic Deformation Processes:Afterslip and Vicoelastic Relaxation Following the 2015 Nepal Mw7.8 Earthquake[J]. Geomatics and Information Science of Wuhan University, 2020, 45(10): 1578-1587. DOI: 10.13203/j.whugis20180349
Citation: LI Yulei, ZHANG Yongzhi, WANG Shuai, LIU Tai. Post-Seismic Deformation Processes:Afterslip and Vicoelastic Relaxation Following the 2015 Nepal Mw7.8 Earthquake[J]. Geomatics and Information Science of Wuhan University, 2020, 45(10): 1578-1587. DOI: 10.13203/j.whugis20180349

2015年尼泊尔Mw7.8地震的震后形变机制—震后余滑效应和黏滞性松弛效应

Post-Seismic Deformation Processes:Afterslip and Vicoelastic Relaxation Following the 2015 Nepal Mw7.8 Earthquake

  • 摘要: 利用较为完善的球体位错理论,结合尼泊尔地震震后1年GPS数据,研究2015年尼泊尔Mw7.8地震震后形变机制。探索了两种不同的震后形变机制模型:①单一的震后余滑模型(模型1);②震后余滑和黏滞性松弛联合模型(模型2)。模型1研究结果表明,震后余滑主要发生在20 ~ 35 km深度处,位于同震破裂的下倾区域;余滑以逆冲为主,伴随有右旋走滑分量,其中最大逆冲和走滑分量分别为20 cm和11 cm;震后余滑释放的地震矩为1.23×1020 Nm,等效于Mw7.33地震。模型2得到的余滑分布与模型1相一致,但累积滑动量略小,释放地震矩为1.1×1020 Nm,等效于Mw7.32地震。模型2研究表明尼泊尔地震震源区岩石圈弹性层厚度和地幔黏滞性系数的最优值分别为40 km和2×1019 Pa·s。综上所述,尼泊尔地震震后1年时间内,震后余滑效应起主导作用,黏滞性松弛效应起次要作用。

     

    Abstract: The post-earthquake deformation mechanism of the 2015 Nepal Mw7.8 earthquake is studied by using the relatively perfect theory of spherical displacement and GPS data of one year after Nepal earthquake. Two different models of post-earthquake deformation mechanism are explored: ① Single post-earthquake afterslip model (model 1); ② Combined model of post-earthquake afterslip and viscous relaxation (model 2). The results of model 1 show that the post-earthquake afterslip mainly occurs at the depth of 20-35 km and is located in the downdip area of co-seismic rupture; the main component of afterslip is thrust, accompanied by dextral strike-slip components, of which the largest component is 20 cm and 11 cm, respectively; the moment released by the post-earthquake afterslip is 1.23×1020 Nm, equivalent to Mw7.33 earthquake. The residual slip distribution obtained by model 2 is consistent with model 1, but the cumulative slip is slightly smaller, and the released seismic moment is 1.1×1020 Nm, equivalent to Mw7.32 earthquake. Furthermore, the results of model 2 show that the optimum values of lithospheric elastic layer thickness and mantle viscous coefficient in Nepal seismic source area are 40 km and 2×1019 Pa·s, respectively. To sum up, the post-earthquake afterslip effect plays a dominant role and the viscous relaxation effect plays a secondary role in Nepal within one year after the earthquake.

     

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