摘要
2008年5月12日汶川MW7.9特大地震发生在龙门山断裂带,龙门山断裂带深部结构的复杂性制约了地震的破裂过程.通过对研究区区域地质、汶川地震前后采集的地震反射剖面等研究,在对龙门山北段汶川地震断裂带的深部结构和反射地震特征进行了分析的基础上,探讨了它对地表破裂过程的制约.研究结果表明,在地震剖面上,断裂带表现为能量破碎、联系性差;频率剖面上显示整体剖面频率在5~45Hz,断裂带呈现频率低(15~26Hz)等特征.龙门山北段映秀—北川断裂在10km以上是一条倾向北西的高角度走滑兼逆冲性质的断裂,倾角50°~70°.它分割了西侧的轿子顶杂岩和东侧的唐王寨推覆体,错断了早期形成的逆冲岩片,从南到北总位移量由大变小.它高角度的几何形态约束了断裂以走滑为主兼逆冲分量的运动性质,降低了地表滑移量,影响了地震破裂过程以及余震沿断裂带两侧分布的特性.
On May 12,2008,the Wenchuan violent earthquake of M_W7.9 occurred in the Longmen Shan fault zone.The complexity of deep structure of the Longmen Shan fault zone restricts the rupture process of the earthquake.Through the study of the regional geology and the seismic reflection profiles collected before and after the Wenchuan earthquake,the deep structure and reflection seismic characteristics of the Wenchuan seismic fault zone in the northern section of the Longmen Shan are analyzed,and the constraints on the surface rupture process are discussed.The results show that the fault zone on the seismic profile is characterized by energy fragmentation and poor connection,and the frequency section shows the overall frequency in 5~45 Hz,and thefault zone is characterized by low frequency（15~26 Hz）.The Yingxiu-Beichuan fault in the northern part of the Longmen Shan is a high angle strike slip and thrust fault with a dip angle of 50~70 degrees above 10 km.It divided the Jiaozideng complex rock on the west side and the Tangwangzhai nappe on the east side,and breaks the early formed thrust sheet,and the total displacement from south to north gradually decreases.Its high angle geometry constrains the movement of fracture,making it mainly strike slip and thrust,and reduced the surface slip,and affected the characteristics of earthquake rupture process and the distribution of aftershocks along both sides of the fault zone.
作者
于常青
冯杨洋
瞿辰
范国玮
李恒强
YU ChangQing1, FENG YangYang2 , QU Chen1 , FAN GuoWei1,3, LI HengQiang1,4(1.Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China ;2China Earthquake Administration Network Center, Beijing 100036, China;3 School of Land and Resources Engineering, Kunming University of Science and Technology, Kunming 650032, China;4 School of Geophysics and Information Technology, China University of Geosciences （Beijing）, Beijing 100083, China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第5期2038-2053,共16页
Chinese Journal of Geophysics
基金
国家科技专项"汶川地震断裂带科学钻探(WFSD)"
中德合作基金项目(41761134096)资助
关键词
龙门山断裂带
汶川地震
深部结构
地震反射剖面
地震反射特征
Longmen Shan fault zone
Wenchuan earthquake
Deep structure
Seismic reflection profile
Seismic reflection characteristics
