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Title:: New Active Characteristics and Seismological Significance of the Yuan'an Fault in the Central Hubei Basin

作者:: 殷娜¹; 2; 余中元¹; 2; 石砚斌¹; 2; 付国超³; (1.防灾科技学院,河北三河 065201; 2.河北省地震动力学重点实验室,河北三河 065201; 3.中国地震局地球物理研究所,北京100010)

Author(s):: YIN Na¹; 2; YU Zhongyuan¹; 2; SHI Yanbin¹; 2; FU Guochao³; (1.Institute of Disaster Prevention,Sanhe 065201,Hebei,China;2.Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,Hebei,China;3.Institute of Geophysics,China Earthquake Administration,Beijing 100010,China)

Keywords:: the central Hubei Basin; the Yuan'an Fault; new activity features; seismogeological significance; the Yangtze Craton

摘要:: 鄂中盆地地处稳定的扬子克拉通内部,但近年来陆续有中等强度地震发生,其孕震机理和发震构造备受关注。通过高密度电法勘探和野外地表地质调查方法,研究了鄂中盆地远安断裂的新活动特征。结果表明:远安断裂在第四纪早期构造变形强烈,运动方式以正断为主兼具右旋走滑分量。尽管断裂晚第四纪以来活动强度逐渐减弱,但仍具备发生中等强度地震的能力。应重视扬子克拉通内部NW或NNW向断裂作为中强地震发震构造的可能性,其潜在地震危险不容忽视。

Abstract:: The central Hubei Basin is located in the interior of the stable Yangtze Craton,but moderate earthquakes have occurred frequently in the Basin in recent years.Thus,its seismogenic mechanism and seismogenic structures have attracted much attention.Taking the Yuan'an Fault in central Hubei Basin as an example,this paper studies its new activity characteristics by means of high-density electrical prospecting and field geological survey.The results show that the tectonic deformation of the Yuan'an Fault was strong in the early Quaternary,and the tectonic mode was mainly dominated by normal movement with dextral strike-slip component.Although the activity intensity of the fault has been gradually weakening since the late Quaternary,it still has the seismogenic capacity of moderate earthquakes.The research also hints that these NW or NWW strike-slip faults with strong deformation in the early Quaternary play an obvious role in controlling modern medium-and strong-earthquakes in the Yangtze Craton.The possibility that these NW trending faults,which may be the seismogenic structures for moderate-and strong-earthquakes in the craton interior,should be paid more attention to and their potential seismic hazards should not be ignored.