龙门山断裂带映秀-北川断裂白沙河段滑动速率  

STUDY ON THE SLIP RATE OF THE BAISHA RIVER SEGMENT IN THE YINGXIU-BEICHUAN FAULT IN THE LONGMENSHAN FAULT ZONE

作　　者：花春雨 石峰[1,2] 魏占玉 HUA Chun-yu;SHI Feng;WEI Zhan-yu(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Shanxi Taiyuan Continental Rift Dynamics National Observation and Research Station,Beijing 100029,China)

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [2]山西太原大陆裂谷动力学国家野外科学观测研究站,北京100029

出　　处：《地震地质》2024年第6期1295-1313,共19页Seismology and Geology

基　　金：国家重点研发计划项目(2021YFC3000601,2023YFC3012001)资助。

摘　　要：龙门山断裂带是青藏高原块体和华南块体的重要边界断裂带,是一条重要的地震活动构造带。几何上自西向东可分为后山断裂、中央断裂、前山断裂和前陆盆地(成都平原)变形带。中央断裂带是龙门山断裂带的主干断裂,映秀-北川断裂是中央断裂带中段活动最强烈的一支断裂。前人对龙门山断裂带映秀-北川断裂滑动速率进行了部分研究,但结果差异很大,范围从0.07mm/a到1.1mm/a不等。断层滑动速率是分析断层活动特征、研究区域运动学和动力学机制的重要依据。文中依据遥感精细解译和野外调查资料,通过10个阶地横剖面及阶地年龄对龙门山断裂带映秀-北川断裂白沙河段的滑动速率进行约束,得到映秀-北川断裂白沙河段晚更新世以来的垂直滑动速率为(0.10±0.02)~(0.30±0.05) mm/a,平均滑动速率为0.19mm/a。该结果可为理解汶川地震的发震构造、龙门山断裂带的整体活动特征及评价龙门山断裂带的长期地震危险性提供基础资料。The tectonic belt stretches approximately 400km from Lushan County to Wenchuan County in an east-west direction.The Longmenshan fault zone can be geometrically divided into several sections,including the Houshan Fault,the Central Fault,the Qianshan Fault,and the Foreland Basin(Chengdu Plain)Deformation Zone.The Central Fault is the main segment of the active tectonic belt in the Longmenshan region,and the Yingxiu-Beichuan Fault is one of the most active segments within this central section.The Yingxiu-Beichuan Fault has experienced numerous moderate and strong earthquakes throughout its history,including the Wenchuan earthquake 2008.The 2008 Wenchuan earthquake was ahigh destructive natural disaster that profoundly impacted the Chinese mainland,leading to significant economic losses and casualties.This earthquake caused extensive building collapses,leading to the loss of tens of thousands of lives,and triggered severe secondary geological disasters such as landslides,rockfalls,and mudflows,severely affecting the normal operation of transportation and communication infrastructure.The Yingxiu-Beichuan Fault was one of the key surface rupture zones during this earthquake.However,there is still some uncertainty about the slip rate of this fault.The Baisha River segment examined in this paper is located in the southern part of the Yingxiu-Beichuan Fault,measuring approximately 14km long.This area contains 14 fractures of varying lengths and complex geometric structures,forming a fracture zone that reaches a maximum width of nearly 300m.The overall orientation of the rupture zone is about 50 degrees;however,the orientation of each small secondary rupture varies,with differences ranging from 0 to 90 degrees.The coseismic displacement along the Baisha River section displays complexity and diversity.The thrust movement primarily occurs on the northern and western walls,with some local thrust faults.Additionally,the strike-slip motion is predominantly right-lateral,exhibiting a maximum horizontal displacement of approximat

关 键 词：龙门山断裂带 映秀-北川断裂 白沙河 滑动速率 

分 类 号：P315.2[天文地球—地震学]