NEW EVIDENCES OF THE HOLOCENE FAULT IN SUQIAN SEGMENT OF THE TANLU FAULT ZONE DISCOVERED BY SHALLOW SEISMIC EXPLORATION METHOD |
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Authors: | XU Han-gang FAN Xiao-ping RAN Yong-kang GU Qin-ping ZHANG Peng LI Li-mei ZHAO Qi-guang WANG Jin-yan |
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Institution: | 1. Earthquake Administration of Jiangsu Province, Nanjing 210014, China;
2. Institute of Geology, China Earthquake Administration, Beijing 10029, China |
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Abstract: | The fault F5 is considered as the most active fault in the Tanlu fault zone(Yi-Shu fault zone), which is located from Weifang of Shandong Province to Jiashan of Anhui Province, with a length of 360km. It has always been a focus of concern to many geoscientists because of its complexity and importance. But, for a long period of time, there exists biggish indetermination in the accurate position and active ages of the fault F5 in Suqian section of Tanlu fault zone. Seismic reflection exploration is the main technique in present urban active faults detecting. In order to investigate the spatial distribution, characteristics and activities of the fault F5 in covered terrains, we carried out a systematic survey to the fault with shallow seismic prospecting method and obtained the accurate position and development characteristics of the fault. The results show that the fault F5 continues to develop toward south rather than ending at the Huancheng South Road of Suqian City. F5 is mainly composed of two main faults, which dip in opposite directions and almost vertically. Near the Sankeshu town, F5 is composed of three faults with right-stepping, forming a small pull-apart basin with length of 6km, width of 2.5km, controlling the deposition of Neogene and Quaternary strata. By combining the results of composite drilling section and trenching, we make a conclusion that the western branch of fault F5 is a Holocene active fault, and the eastern branch is a Pleistocene active fault. Our general view is that fault F5 is a Holocene active fault. |
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Keywords: | shallow seismic exploration Suqian section of Tanlu fault zone fault F5 |
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