2017年四川九寨沟M_s7.0地震的地震学特征  

Seismologic characteristics of the 2017, M_s7.0 Jiuzhaigou earthquake, Sichuan, China

作　　者：安艳茹[1,2] 苏金蓉 薛艳[1] 张莹莹[1] 白兰淑[1] 刘杰 何少林[1] 杨志高[1] 杜广宝[1] 魏娅玲[3] 吴微微[3] 黄春梅[3] 潘颖[4] Yanru An1,2, Jinrong Su3, Yan Xue1, Yingying Zhang1, Lanshu Bai1, Jie Liu1 , Shaolin He1, Zhigao Yang1, Guangbao Du1, Yaling Wei3, Weiwei Wu3, Chunmei Huang3 ＆ Ying Pan4(1 China Earthquake Networks Center, Beijing 100045, China; 2 Institute of Geophysics, China Earthquake Administration, Beijing 100081, China 3 Earthquake Administration of Sichuan Province, Chengdu 610041, China; 4 Earthquake Administration of Jiangsu Province, Nanjing 210014, Chin)

机构地区：[1]中国地震台网中心,北京100045 [2]中国地震局地球物理研究所,北京100081 [3]四川省地震局,成都610041 [4]江苏省地震局,南京210014

出　　处：《科学通报》2018年第7期663-673,共11页Chinese Science Bulletin

基　　金：中国地震局地震科技星火计划(XH17048);中国地震局地震行业科研专项(201508012)资助

摘　　要：2017年九寨沟M_s7.0地震位于巴颜喀喇地块东边界带附近的虎牙断裂NNW方向的延长线上,震源深度20km,震源机制解为左旋走滑型,矩震级为M_w6.5.震后6 d内共记录到3000多次余震,最大震级为M4.8,余震活动强度偏低但衰减正常.主震位于余震区中部,为双侧破裂.余震区呈NNW向线性分布,断层面近乎直立,长度超过30 km,破裂宽度约15 km.余震区中部、东南部余震的震源机制大多与主震震源机制一致,而西北部余震的震源机制均为逆冲型,可能与岷江断裂有关.余震区中部、东南部的应力也较西北部释放充分.九寨沟地震最大烈度为9度,记录的峰值加速度值NS向最大,EW向次之,垂直向最小,最近的强震台是九寨百河台,其加速度反应谱低于九寨沟地区的8度设防烈度.静态库仑应力研究表明,汶川地震对九寨沟地震具有较明显的触发作用.沿虎牙断裂发生的1973年松潘东北M_s6.5地震,1976年松潘M_s7.2地震和本次九寨沟地震的余震区沿NNW方向相连.结合主震破裂位移分布、余震的震源机制及应力降分析认为,九寨沟地震余震区中部、东南部发生强余震的危险性不大,但需注意余震区西北部及岷江断裂地震活动的发展.The Ms7.0 Jiuzhaigou earthquake with the hypocenter depth of 20 km occurred at the NNW extension line of the Huya fault located next to the eastern boundary of the Bayan Har block. The focal mechanism solution of the mainshock based on the W-phase source inversion showed a sinistral slip and the moment magnitude was Mw 6.5. Over 3000 aftershocks were recorded within six days, among which the largest was M4.8 and three others were larger than M4.0. The value of the aftershock frequency attenuation coefficient P was 1.03, and the b value of the magnitude-frequency relationship was 0.68. The aftershock activities were relatively inactive but the attenuation was normal. Relocation results of 603 after- shocks were obtained by using the double-difference earthquake location algorithm and the location errors of the EW, NS and the vertical directions were 0.81, 0.84 and 1.59 km respectively. The mainshock occurred in the center of the after- shock region and ruptured on both sides along the strike direction. The aftershocks were distributed linearly along a NNW direction, and the fault plane was nearly vertical with a length over 30 km and a width of about 15 km. Aftershocks were more concentrated in the southeast than in the northwest. The focal mechanism solutions of most aftershocks in the central and southeastern regions were consistent with the mainshock, while those in the northwest were thrnst-types, which might be related to the Minjiang fault. Meanwhile, the regional stress was released more in the central and south- eastern regions than in the northwest. The maximum intensity investigated in the damage zone was up to IX. The maxi- mum intensity region was located in scenic areas, therefore few people were present when the earthquake occurred at night. The peak acceleration was highest in the NS records, followed by the EW and vertical records. The design spectra of intensity for Jiuzhaigou was VIII, which is higher than the acceleration response spectra obtained from the Jiuzhaibai- he station, the nearest sta

关 键 词：九寨沟Ms7.0地震 地震震源机制 余震精定位 峰值加速度 虎牙断裂 库仑应力触发 汶川地震 

分 类 号：P315[天文地球—地震学]