四川康定—磨西断裂强震危险背景研究  

Study on the risk background of strong earthquake in Kangding-Moxi fault,Sichuan

作　　者：环文林[1] 张萌[1] 潘华[1] Huan Wenlin;Zhang Meng;Pan Hua(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]中国地震局地球物理研究所,北京100081

出　　处：《地震科学进展》2024年第10期671-679,共9页Progress in Earthquake Sciences

摘　　要：本文对四川西部鲜水河断裂带上的康定—磨西断裂的强震危险性作了分析探讨。该断裂位于川西—滇东第Ⅲ弧形挤出构造带的弧顶转折部位,这里应力高度集中,块体左旋大幅度滑移,断裂两侧垂直差异运动幅度达1000~2000 m,为大陆板块内部断裂活动性较高的地震区。鲜水河断裂带是我国地震活动性和重复性都很高的一条左旋走滑断裂带,自1725年至今接近300年的时间里,鲜水河断裂带上重复出现了2期地震活动,地震重复周期为100~200年。康定—磨西断裂于1786年发生过7¾级大地震,此地震发生迄今已237年,断裂一直处于能量积累的相对平静期。近期地震活跃起来,2022年9月6.8级四川沪定磨西地震以后5.6级以下的中小震频繁发生,并沿着磨西断裂成带分布,是否预示着该断裂又重新活动起来,进入新的地震活动期?这些特征表明康定—磨西断裂具有大地震孕育发生的背景条件。In this paper,the strong earthquake risk of the Kangding-Moxi fault,located within the Xianshuihe fault zone in western Sichuan,is analyzed and discussed.The fault at the apex of the third arc extrusion structural belt extends from western Sichuan to eastern Yunnan.This area is characterized by high stress concentration,substantial left-lateral slip,and a vertical differential movement between the two sides of the fault ranging from 1000 to 2000 meters.It is one of the most seismically active regions within the continental plate.The Xianshuihe fault zone is a left-lateral strike-slip fault zone with high seismicity and earthquake recurrence in China.Over the nearly 300 years since 1725,two periods of seismicity have repeatedly occurred on the Xianshuihe fault zone,with recurrence intervals of 100 to 200 years.The Kangding-Moxi fault was the site of a major earthquake,with a magnitude of 7¾,in 1786.It has been 237 years since that event,and the fault has been in a relatively quiet phase of energy accumulation.However,recent earthquakes have become active.Following the MS6.8 Moxi earthquake in Luding,Sichuan Province in September 2022,medium and small earthquakes with M<5.6 occurred frequently and along the Moxi fault.This raises the question of whether the fault is reactivating and entering a new period of seismic activity.These characteristics indicate that the Kangding-Moxi fault has the background conditions for the occurrence of large earthquakes.

关 键 词：康定—摩西断裂 鲜水河断裂带 鲜水河-滇东挤出构造 地震活动重复周期 大地震危险性 

分 类 号：P315.5[天文地球—地震学]