2022门源M_(S)6.9地震地表破裂带震害特征调查

Seismic disaster characteristics of the surface rupture of Menyuan M_(S)6.9 earthquake in 2022

2022年1月8日,青海省海北藏族自治州门源县发生M_(S)6.9地震,震中位于青藏高原东北缘地区祁连—海原断裂带的冷龙岭断裂和托勒山断裂构造转换区域(37.77°N,101.26°E)。震后野外现场考察结果表明,此次地震形成的同震地表破裂带总长度约为26 km,整体走向NWW向,破裂性质以左旋走滑局部逆冲为主。断层错动造成的破坏形式以雁列式组合的张裂隙、张剪裂隙、挤压鼓包、断层陡坎等为主。其中,道河至硫磺沟段地表破裂最为强烈,规模大且连续性好,造成的震害最为显著,地表破裂规模向东、西两端逐渐衰减。破裂带穿过区域内多条河流,造成显著的冰面破裂变形,并沿河岸形成一系列的边坡崩塌、滚石等地质灾害。综合破裂带及震害规模分析,宏观震中位于道河至硫磺沟地区。

An M_(S)6.9 earthquake occurred in Menyuan County,Qinghai Province,on January 8th,2022.The epicenter is located at the tectonic transform region of the Lenglongling fault and Tuoleshan fault along the Qilian-Haiyuan fault zone(37.77°N,101.26°E)of the northeastern Tibetan Plateau.This paper introduced the typical earthquake disasters and characteristics of co-seismic surface ruptures.The results of field investigation after the earthquake showed that the main shock ruptured two obvious surface zones with the length up to 26 km,and the overall strike was directed along NWW.The rupture property is mainly sinistral strike-slip with thrusting slip by dipping to NE.The typical rupture landforms caused by fault dislocation mainly exhibit as en echelon combined of separation fractures,tension shear fractures,seismic bulges,and fault scarps.The surface rupture at the segment from Daohe to Liuhuanggou is the strongest,with large scale and good continuity,causing the most significant earthquake damage,and the scale of the surface rupture gradually decreases to the east and west ends.The main shock ruptured the ice surface of the Daohe and the Liuhuanggou,with typical deformation of a series of fractures and bulges as well as small scale of geological disasters,such as slope collapse and rolling stones formed along the river bank.Based on the comprehensive analysis of post-earthquake damage and surface rupture distribution,the region between Liuhuanggou and Daohe can be determined as the macro epicenter of the Menyuan M_(S)6.9 earthquake.