摘要
概述了2008年汶川8.0级地震后近10年有关龙门山断裂带的深浅部变形研究结果,通过较为系统的综合对比分析,归纳得出的基本共识为:龙门山断裂带的深部构造形态和速度结构均十分复杂,2008年汶川8.0级地震是由多次子事件构成的十分复杂破裂过程,其主要滑动量在深浅部都有展布.综合分析认为:龙门山断裂带中北段的深浅滑动速率存在明显差异,孕震深处的滑动速率约为浅部的2~3倍,以重复地震分析给出的深部滑动速率估算的汶川地震复发间隔约为500~4500 a.针对探测程度十分有限的大陆内部断裂带,应充分发挥重复地震的原位探测优势,集成地震学、大地测量学和地质地貌学的各自优势进行深浅部构造变形的有效探测分析,对断裂闭锁段和深浅构造变形差异显著地区的强震危险性尤应重视.
This paper reviews studies of the past ten year related to the crustal deformation of the Longmenshan fault zone（LMSFZ） which was struck by the M8.0 Wenchuan earthquake on May 12, 2008. The tectonics of the LMSFZ located at the eastern margin of the Tibetan Plateau is complex, with complicated fault geometry and a heterogeneous velocity structure. The Wenchuan earthquake rupture extended for about 300 km along the middle and northern segments of the LMSFZ, with a very complicated rupture process involving multiple sub-events. The Wenchuan slip distribution is characterized by two major slip patches near Hongkou/Yingxiu and Beichuan with peak slip of 5.0–15.5 m and extended from near the surface to below 20 km depth. Prior to the Wenchuan earthquake, the LMSFZ had been seismically quiet for several centuries and there were no hints that suggested that such an M8.0 earthquake might strike the area. The long-term geological investigations and short-term geodetic measurements before the Wenchuan earthquake generally agree that the horizontal slip rate along the LMSFZ is no more than 3 mm per year. The low slip rate observed at the surface around the LMSFZ may not reveal the real state of accumulated strain at depth where the devastating Wenchuan earthquake nucleated. Rates of aseismic slip at depth derived from seismological investigation of repeating microearthquakes were found to be approximately twice as large as the interseismic rates inferred from surface GPS and geological data. Most of the clusters of repeating microearthquakes are located at the edge of locked areas where large coseismic slips were observed during the Wenchuan earthquake, suggesting a close relationship between microearthquakes and impending large earthquakes. A two-dimensional viscoelastic finite-element model produces a depth-related slip rate pattern around the LMSFZ that is consistent with that revealed by the seismological observation of repeating earthquakes. The measured in situ deep slip rates increase with depth and vary from 3
作者
陈棋福
李乐
Qi-Fu Chen;Le Li(Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China 2 Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China;3 College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,Chin;4 Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2018年第19期1917-1933,共17页
Chinese Science Bulletin
基金
国家自然科学基金(41474041,41474031和41774058)资助
关键词
汶川地震
龙门山断裂带
深部变形
重复地震
强震危险性
复发间隔
Wenchuan earthquake
Longmenshan fault zone
deep deformation
repeating earthquakes
seismic hazard
recurrence interval
