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Title:: Regional Crustal Horizontal Deformation Characteristics before Yunnan Tonghai M_S5.0 Earthquakes in 2018

Author(s):: JIANG Fengyun; ZHU Liangyu; JI Lingyun; LI Ning; WANG Shuangxu; (The Second Crust Monitoring and Application Center,China Earthquake Administration,Xi'an 710054,Shaanxi,China)

Keywords:: Tonghai M_S5.0 earthquake; crust deformation; GPS; strain rate field

摘要:: 利用1991—2015年GPS观测地壳长期水平运动速度场,研究了2018年8月13,14日云南通海2次5.0级地震前附近区域地壳水平形变背景特征,结合构造分析认为:(1)通海地震发生在区域地壳水平运动受阻,应变快速积累部位,即面应变率和最大剪应变率的高值区。该部位亦是小江断裂带和曲江—石屏断裂带的交汇部位,从背景形变特征来看,该区域及其附近未来稍长一段时间再次发生中强地震的危险性依然存在。(2)个旧与弥勒之间为另一个应变快速积累部位,应警惕未来发生中强地震的可能。

Abstract:: According to crustal long-term horizontal movement field of GPS observation from 1991 to 2015,we studied the deformation features of crustal horizontal movement in epicenter area before two Yunnan Tonghai M_S5.0 earthquakes occurred on Aug.13 and Aug.14 in 2018.Combined with the tectonic,the results show that:(1)The Tonghai earthquakes occurred in the region where the crustal horizontal movement was hindered and the strain energy accumulated rapidly,that is,the high value area of the plane strain rate and the maximum shear strain rate.The region is also located at the intersection of Xiaojiang Fault system and Qujiang Shiping fault system.According to the characteristics of background deformation,the study area still has a high risk of moderate-strong earthquake in the future.(2)Another rapid strain accumulation zone is lying at the area between Gejiu and Mile,we should pay attention to the possibility of moderate-strong strong earthquakes in the future.