2010年玉树地震库仑应力变化对2016年杂多地震的影响及区域危险性评估

在以往研究的基础上，利用弹性位错理论和岩石圈分层粘弹性模型，进一步分析2010年玉树地震同震及震后应力变化对2016年杂多地震的影响，讨论玉树地震和杂多地震对研究区主要活动断裂的应力影响及未来地震危险性。结果表明，玉树地震同震库仑应力使杂多地震震中位置应力升高1.476 kPa。2010年玉树地震至2016年杂多地震的6 a内，震后粘弹性松弛作用使研究区域库仑应力增强区域应力持续集中，并使应力影区进一步释放应力，杂多地震位于玉树地震导致的库仑应力增强区域。2016年杂多地震发生时，其震中位置应力升高3.902 kPa。采用多组不同模型参数的研究结果均显示，玉树地震对杂多地震孕育起促进作用。2016年杂多地震同震破裂仅影响震中周边小范围区域的应力状态，在杂多断裂带西北端出现应力高值区域。2010年玉树地震同震及震后作用使甘孜-玉树断裂的叶诺卡-结隆段、巴塘乡-洛须段、当江段、巴塘乡断裂中段及五道梁-曲麻莱断裂称多段应力明显升高。甘孜-玉树断裂西北段的叶诺卡-结隆段、巴塘乡-相古段地震空区的地震危险性较高。

Coulomb Stress Influence of 2010 Yushu Earthquake on 2016 Zaduo Earthquake: Earthquake and Seismic Hazard Assessment on Surrounding Area

Based on elastic dislocation theory and lithosphere layered viscoelastic model, we analyze the influence of the co-seismic and post-seismic stress of the Yushu earthquake on the Zaduo earthquake. Additionally, we discuss the stress influence of Yushu and Zaduo earthquakes on the major active faults about seismic risk in the study area. The result shows that the co-seismic stress increased 1.476 kPa on the epicenter of the 2016 Zaduo earthquake. During the 6 years between the two earthquakes, post-seismic Coulomb stress enhanced regional stress in the area, and released stress in the stress shadow; the epicenter of the Zaduo earthquake is always located in the area of enhanced stress. When the Zaduo earthquake occurred, the Coulomb stress increased 3.902 kPa on the epicenter of the Zaduo earthquake. The results of different models show that the occurrence of Yushu earthquake promoted the occurrence of Zaduo earthquake. The co-seismic rupture of Zaduo earthquake only affected the stress state of a small area around the epicenter, which made a high stress area in the northwest of Zaduo fault zone. The co-seismic and post-seismic effect of Yushu earthquake significantly enhanced the stress state of the Yenuoka-Jielong segment, Batang-Luoxu segment, Dangjiang segment, the middle segments of Batangxiang and Wudaoliang-Qumalai faults. The northwest seismic gaps of Ganzi-Yushu fault, including the Yenuoka-Jielong and Batang-Xianggu segments, retain arelatively high seismic hazard.