2015年尼泊尔8.1级地震与喜马拉雅弧的历史地震研究  

Research on Nepal M8.1 Earthquake in 2015 and Historical Earthquakes along the Himalayan Arc

作　　者：杜方[1] 旦增 朱德富 土登次仁 益西拉姆 曹华文 米玛次仁 梁明剑[1] 

机构地区：[1]四川省地震局,四川成都610041 [2]西藏自治区地震局,西藏拉萨850000

出　　处：《地震研究》2016年第2期177-186,共10页Journal of Seismological Research

基　　金：中国地震局地震行业科研专项(20140823)资助

摘　　要：2015年4月25日在喜马拉雅弧的尼泊尔博克拉发生8.1级大地震,2015年4月25日至5月12日相继发生尼泊尔7.0、7.1和7.5级大震。根据西藏地震台网资料和收集到的国内外相关资料,分析了尼泊尔8.1级地震的基本参数、余震分布、序列衰减以及喜马拉雅弧的历史破裂等特征。结果表明：尼泊尔8.1、7.0、7.1和7.5级地震的震源力学机制均显示为低倾角的纯逆冲性事件,破裂面走向平行于NWW—SEE的喜马拉雅边界,以5°～11°倾向北;从定性的角度分析,尼泊尔8.1级地震可判定为独特的主—余型地震,其余震分布长轴走向显示与喜马拉雅主边界走向一致,密集区NWW—SEE向长轴和S—N向短轴大约分别为200 km和150 km;估计2015年尼泊尔8.1级地震破裂尺度与1833年尼泊尔加德满都北部大震相当,比1934年的尼泊尔—印度（比哈尔邦）间大震略小。据历史地震破裂空段推测,2015年尼泊尔8.1级地震破裂填充在1505年大震与1833年大震两次历史破裂之间的空段。On Apr. 25,2015,an Nepal M8. 1 strong earthquake in the Pokhara of Nepal occurred on the Himalayan arc. The three strong events of M7. 0,M7. 1 and M7. 5 had occurred in Nepal from Apr. 25 to May. 12,2015.According to the data of Tibet Seismic Network and the current correlative information from internal and overseas,we analyzed the basic seismic parameters,aftershock distribution and sequence attenuation of Nepal M8. 1earthquake,and other characteristics of historical rupture along Himalayan arc. The results showthat the focal mechanisms of the Nepal M8. 1,M7. 0,M7. 1 and M7. 5 earthquakes are almost the pure thrust events with a low-angle and shown as the rupture plane strikes parallel to the Himalayan belt in NWW-SEE,and the dips with5° ～ 11° to the NNE. From a qualitative point of view,the Nepal M8. 1 earthquake can be determined a typical main shock-aftershock sequence. The trend of the long axis of aftershocks distribution ellipsoid was consistent with the trend of main boundary of Himalayan belt structural. The lengths of the long axis in NWW-SEE and short axis in S—N of the aftershocks distribution ellipsoid are about 200 km and 150 km respectively. It is estimated that the rupture zone of the 2015 M8. 1 Nepal earthquake is similar to that of the 1833 MW7. 7 Nepal earthquake in the North of Kathmandu,and is smaller than that of the 1934 MW8. 1 Nepal-India（ Bihar） earthquake.From the historical seismic gap,the rupture zone of the 2015 M8. 1 Nepal earthquake filled the seismic gap between the two historical rupture of the 1505 earthquake and the 1833 earthquake.

关 键 词：尼泊尔8.1级地震 震源力学机制 主喜马拉雅逆冲断裂 历史地震 

分 类 号：P315.7[天文地球—地震学]