DISTRIBUTION OF YANGJIA VILLAGE-YAODIAN SECTION OF WEIHE FAULT AND THE CHARACTERISTICS OF ITS LATE QUATERNARY ACTIVITY |
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| Authors: | TIAN Qin-hu ZHOU Ben-gang LI Xiao-ni SHI Jin-hu WEI Qing-ke BIAN Ju-mei |
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| Affiliation: | 1. Earthquake Administration of Shaanxi Province, Xi'an 710068, China;
2. Institute of Geology, China Earthquake Administration, Beijing 100029, China;
3. Geophysical Exploration Center, China Earthquake Administration, Zhengzhou 450002, China |
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| Abstract: | The Yangjia Village-Yaodian segment of Weihe Fault, starting from Yangjia Village in the west, passing through Weijiaquan, Jinjiazhuang, Donger Village, Chenjiatai to Yaodian, occurs as a NE-striking fault dipping south with a total length of 33 kilometers. As a syn-depositional normal fault, it extends along the leading and trail edge of T1, T2 and T3 terrace at the northern bank of Weihe River. Results of remote sensing interpretation, shallow seismic exploration, exploratory trench, and drilling show that the Yangjia Village-Yaodian section of Weihe Fault manifests as fault scarps, overlapping with the NE-extending terrace scarp at the northern bank of Weihe River. Weihe Fault broke the T1 that can be distinguished on the shallow seismic profile and multiple profiles with broken signs from T1 to the ground, which is the same with the cracks through the Han Tomb at the top of the exploratory trench in Yangjia Village. It shows that the fault may still be active from the late Pleistocene to Holocene. Through composite drilling section and the analysis of exploratory trench, there is no significant difference in activity between the Yangjia Village-Jinjiazhuang and Donger Village-Yaodian section. This segment has experienced a large displacement event since (46.0±3.3)ka BP, approximately 11.0~16.5m, with a vertical slip rate of 0.34~0.45mm/a. The most recent activity occurred approximately around 2.0ka BP. The left-step en echelon fracture zone at Jingjiazhuang separates this section into two minor ones, Yangjia Village-Jinjiazhuang section and Donger Villag-Yaodian section. Yangjia Village-Yaodian section in Weihe Fault and Yaodian-Zhangjiawan section which was found out in the Xi'an active fault detection and seismic risk assessment project can be combined into the Yangjia Village-Zhangjiawan section. |
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| Keywords: | Weihe Fault distribution shallow seismic exploration trench terrace scarp |
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