2022年1月8日青海门源M_(S)6.9地震深部构造背景浅析  

The deep tectonic background of the M_(S)6.9 Menyuan earthquake on January 8,2022 in Qinghai Province

作　　者：王琼[1] 肖卓 武粤[1] 李抒予 高原[1] Wang Qiong;Xiao Zhuo;Wu Yue;Li Shuyu;Gao Yuan(Key Laboratory of Earthquake Prediction,Institute of Earthquake Forcasting,China Earthquake Administration,Beijing 100036,China;South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China)

机构地区：[1]中国地震局地震预测研究所地震预测重点实验室,中国北京100036 [2]中国科学院南海海洋研究所,中国广州510301

出　　处：《地震学报》2022年第2期211-222,共12页Acta Seismologica Sinica

基　　金：国家自然科学基金(42074065,4180040231,42104103);国家重点研发计划(2017YFC1500304)联合资助.

摘　　要：2022年1月8日青海境内的托莱山—冷龙岭断裂附近发生了门源MS6.9地震。结合地壳厚度、速度结构及各向异性等资料探讨了门源地震的深部构造特征,揭示了门源地震的发震位置与地壳结构变化的密切关联。结果显示:门源MS6.9地震发生在地壳厚度和vP/vS值都出现快速空间变化的区域;大约在10—20 km深度范围内,震源位于P波速度从浅到深由高速变低速的垂向过渡区,同时也是S波速度和泊松比分布呈现明显横向变化的过渡区域,震源下方存在明显的低速区;冷龙岭断裂两侧相速度的方位各向异性变化比较明显。1月12日的MS5.2余震震中紧邻2016年MS6.4地震震中,揭示出2022年门源MS6.9地震及其余震活动导致了冷龙岭断裂比较充分的破裂,两次门源地震主震之间及邻区短时间内难以积累更大能量,因而短时间内发生更大地震的可能性不大。青藏高原东北缘的持续向北扩展所导致的地表隆升和地壳增厚是该地区强震频发的主要构造成因。On January 8,2022,the Menyuan MS6.9 earthquake occurred on the Lenglongling fault in Qinghai Province.Combining the data of crustal thickness,velocity structure and anisotropy,we discussed the deep structural characteristics of the Menyuan earthquake,and revealed that the location of the Menyuan earthquake is closely related to the structural vari-ations in the crust.The results show that,Menyuan MS6.9 earthquake occurred in the area where both the crustal thickness and vP/vS ratio showed rapid spatial changes.Roughly in the depth range of 10−20 km,the hypocenter is located in the vertical transition zone from shallow to deep where the P-wave velocity changed from high to low,and also the S-wave velocity and Poisson’s ratio distribution show obvious lateral changes and there is a clear low-velocity zone beneath the hypocenter;the variation of azimuthal anisotropy of phase velocity on both sides of the Lenglongling fault is relatively obvious.The epicenter of the MS5.2 aftershock on January 12 was close to that of the 2016 MS6.4 earthquake,revealing that the Menyuan MS6.9 earth-quake and its aftershocks caused a relatively sufficient rupture of the Lenglongling fault.Between the two Menyuan earthquakes and its adjacent areas,it is difficult to accumulate more energy in a short time,so it is unlikely that a larger earthquake will occur in a short time.The continuous northward expansion of the northeastern margin of the Qinghai-Tibet Plateau leads to surface uplifting and crustal thickening,which is the main tectonic cause of frequent strong earthquakes in this region.

关 键 词：门源 M_(S)6.9 地震 震源深度 速度结构 泊松比 地壳厚度 各向异性 

分 类 号：P315.63[天文地球—地震学]