2021年新疆皮山M_(S)5.4和叶城M_(S)5.4双震序列及青藏高原西北缘地震活动特征  

The 2021 Pishan M_(S)5.4 and Yecheng M_(S)5.4 Earthquake doublet and seismicity feature in the Northwestern margin of the Tibetan Plateau

作　　者：罗钧[1] 左可桢 赵翠萍[1] LUO Jun;ZUO KeZhen;ZHAO CuiPing(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国地震局地震预测研究所,北京100036

出　　处：《地球物理学报》2023年第4期1481-1495,共15页Chinese Journal of Geophysics

基　　金：国家重点研发计划课题"应力与震源参数变化智能提取技术研发"(2021YFC3000703);中国地震局地震预测所所基金专项"金沙江下游白鹤滩水库地震危险性研究"(CEAIEF20220401)共同资助。

摘　　要：利用新疆、西藏区域台网记录的P波和S波到时数据,对2009年1月至2021年9月期间的青藏高原西北缘的地震事件开展了精定位;利用新疆区域台网的地震波形数据,对2021年9月4日皮山M_(S)5.4地震和9月5日叶城M_(S)5.4双震序列中的12次M_(S)≥3.5地震事件开展了震源机制解反演;综合精定位与震源机制解结果,分析了皮山M_(S)5.4和叶城M_(S)5.4双震序列的震源特征;结合本文作者已取得的于田地区强震活动性研究结果,讨论了青藏高原西北缘两个强震区内(皮山—叶城地区与于田地区)的强震相关性.研究结果表明,(1)皮山M_(S)5.4和叶城M_(S)5.4双震序列的发震断层为NW向的泽普断裂带,两次M_(S)5.4地震的质心深度为17 km左右.(2)皮山M_(S)5.4和叶城M_(S)5.4地震之间伴有NE-SW向的次级隐伏拉张断层破裂.(3)2015年皮山M_(S)6.5地震序列呈现出NW向的单侧破裂,其余震区与此次皮山M_(S)5.4和叶城M_(S)5.4双震序列余震区没有重叠,两者属于不同的地震序列.(4)近年来,青藏高原西北缘"盆山交接地带"上的于田地区和皮山—叶城地区的强震活动性特征、发震构造模式及局部的构造动力源均不同.以东经80°为界,在其东侧的于田地区,大部分地震沿着NE向大型断裂带分布,少数地震沿着近乎NS向或NNE-SSW向的条带展布;断层错动方式以正断型或走滑型为主.在其西侧皮山—叶城地区,大部分地震活动沿着NW向分布,少量地震沿着NNE向的条带展布;断层错动方式以逆冲错动为主.Using P-wave and S-wave arrival time data recorded by the Xinjiang regional seismic network,seismic events that occurred from January 2009 to September 2021 are relocated.Using seismic waveform data from the Xinjiang regional seismic network,focal mechanism solutions of 12 M_(S)≥3.5 earthquakes have been inversed.By combining results of high-precision relocation and focal mechanisms,source characteristics of the Pishan M_(S)5.4 and Yecheng M_(S)5.4 earthquake doublet sequence were analyzed.Combining seismic research results in the Yutian region obtained by the authors,the correlation between strong earthquakes in the Pishan and Yecheng area and the Yutian area has been discussed.Results are shown as follows(1)The seismogenic fault of Pishan M_(S)5.4 and Yecheng M_(S)5.4 earthquake doublet is the northwest-trending Zepu fault.Centroid depths of two M_(S)5.4 earthquakes are both around 17 km.(2)There is a hidden fault which trends from northwest to southeast between the Pishan M_(S)5.4 earthquake source and the Yecheng M_(S)5.4 earthquake source.(3)The 2015 Pishan M_(S)6.5 earthquake is a unilateral rupture event.There is no overlap between aftershock zone of the Pishan M_(S)6.5 earthquake and that of the Pishan M_(S)5.4 earthquake and Yecheng M_(S)5.4 earthquake doublet.(4)In recent years,characteristics of the strong seismic activity,patterns of seismogenic structure,and dynamic sources of local structure in the Yutian region and the Pishan—Yecheng region are different.The 80°E meridian is chosen as the division.In the Yutian area to the east of it,most earthquakes are distributed along large-scaled northeast-trending faults,and a few earthquakes are distributed along smaller-scaled faults which trend from north to south or from north-northeast to south-southwest.Normal-and strike-slip faulting are the main types of faults.In the Pishan—Yecheng area to the west of it,most earthquakes are distributed along large-scaled northwest-trending faults,and a few earthquakes are distributed along smaller-scaled nort

关 键 词：皮山—叶城地区 双震序列 青藏高原西北缘 

分 类 号：P315[天文地球—地震学]