摘要
利用区域测震台网的地震波形及震相数据基于CAP方法反演北纬26°~42°,东经90°~110°内的270个MS>3.0以上地震的震源机制解;并结合GCMT目录和一些前人研究结果中该区域的共759个震源机制解数据,运用SATSI方法计算了研究区域的应力场。将研究区域按1°×1°网格化后得到了154个局部应力场分布结果,从结果上看,整个青藏高原的最大主压应力方向大致表现为顺时针且向右的旋转方式。该结果反映了青藏高原块体向NE和NNE挤压的过程中,分别在其北部和东部受到鄂尔多斯和阿拉善两个坚硬块体的阻挡,造成青藏块体增厚,块体之间物质的侧向流动。对研究区域应力型因子R值的研究显示青海祁连、甘东南区域、四川龙门山断裂带等沿青藏高原块体与阿拉善块体以及鄂尔多斯块体交界处相对应力值偏大,与近年来这些地区的地震活动性成正比。本文研究结果对比其他应力场研究结果、GPS研究结果、以及数值模拟结果具有很好的一致性,可为青藏高原地区的孕震机理、活动构造以及地震趋势判定提供可靠的参考依据。
In this paper,the cut-and-paste(CAP)method was used to calculate and study the focal mechanism solutions of 270 MS>3.0 earthquakes in the range of 26°N-42°N and 90°E-110°E based on the seismic observation data of the regional seismic network.Then combining the global centroid moment tensor(GCMT)catalog and the data of 759 focal mechanism solutions,the stress field in the study region was calculated using the spatial and temporal stress inversion(SATSI)method.The distribution results of 154 stress fields were obtained by meshing the study area into 1°×1°.Compared with the early tectonic stress field,the direction of maximum principal compressive stress had a clockwise rotation.The results showed that in the extrusion process of the Tibetan Plateau block toward NE and NNE,the northern and eastern parts of the block were stopped by two hard blocks:Ordos and Arashan,respectively,resulting in the thickening of the Tibetan block and the lateral flow of material between the blocks.The study of the R value of the stress form factor in the whole study area showed that the relative stress along the boundary of the Tibetan Plateau block such as the Qilian Mountain in Qinghai,southeastern Gansu,and Longmenshan in Sichuan is large;the relative stress is directly proportional to the seismicity of these areas in recent years.The results of this research agree well with the study results of stress field,GPS research,and numerical simulation.The research results can provide a reliable reference for earthquake initiation mechanism,active structure,and seismic trend determination in the Tibetan Plateau.
作者
尹欣欣
李少华
邹小波
刘旭宙
YIN Xinxin;LI Shaohua;ZOU Xiaobo;LIU Xuzhou(Gansu Earthquake Agency, Lanzhou 730000, Gansu, China;Open Laboratory of Loess Earthquake Engineering, China Earthquake Administration, Lanzhou 730000, Gansu, China;Gaotai Seismic Station of Gansu Earthquake Agency, Gaotai 734300, Gansu, China)
出处
《地震工程学报》
CSCD
北大核心
2020年第5期1065-1076,1084,共13页
China Earthquake Engineering Journal
基金
中国地震局地震预测研究所基本科研业务费专项(2019IESLZ07,2015IESLZ04)
国家自然科学基金(41601479)
中国地震局地震科技星火计划项目(XH19043)。
关键词
震源机制解
构造应力场
青藏高原
滑动角
CAP震源机制解法
focal mechanism solution
tectonic stress field
Tibetan Plateau
slip angle
CAP focal mechanism solution
