SEISMOLOGY AND EGOLOGY ›› 2022, Vol. 44 ›› Issue (1): 35-45.

• Research paper •

### THE LATE QUATERNARY ACTIVITY AND DISPLACEMENT RATE OF FUSHAN FAULT IN SHANXI

YAN Xiao-bing1)(), ZHOU Yong-sheng2),*(), LI Zi-hong1), HU Gui-rang1), REN Rui-guo1), HAO Xui-jing1)

1. 1) Institute of Earthquake Disasters, Shanxi Earthquake Agency, Taiyuan 030002, China
2) State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
• Received:2021-08-31 Online:2022-02-20 Published:2022-04-20
• Contact: ZHOU Yong-sheng

### 山西浮山断裂的晚第四纪活动与位移速率

1. 1)山西省地震局, 太原 030002
2)中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029
• 通讯作者: 周永胜
• 作者简介:闫小兵, 男, 1978年生, 2008年于中国地震局地质研究所构造地质学硕士学位, 高级工程师, 主要从事活动构造和构造地貌学研究, 电话: 13466852098, E-mail: 42953033@qq.com
• 基金资助:
山西省应用基础研究计划项目(201901D111463);中国地震局地震科技星火计划项目(XH18011);山西太原大陆裂谷动力学野外站计划项目(NORSTY20-05);中国地震局地震预测研究所基本科研业务专项(2017IES0101)

Abstract:

An earthquake of M6½ occurred near Fushan County in the 9th year of Dading Period of the Jin Dynasty(in 1209), which caused a large number of casualties and property losses. Many experts and scholars speculated that the Fushan Fault might be its seismogenic structure, but no in-depth research has been conducted, which greatly hinders the development of earthquake prevention and disaster reduction in the region. The Fushan Fault is located on the east side of the Linfen fault basin in the Shanxi fault depression zone. It is a boundary fault between the Linfen fault basin and the uplift area of the Taihangshan block. Predecessors have done little research on the Fushan Fault. This paper carries out a quantitative study on the late Quaternary activity and displacement rate of the Fushan Fault. First, we carried out remote sensing interpretation, fault surface excavation, collection and testing of fault geomorphological samples in the area of Qianjiao village of Fushan Fault. It is determined that the Fushan Fault starts from Hanzhuang village, Beihan Town in the north, extends to the southwest through Yushipo village, Fenghuangling village, Baozishang village, Zhaojiapo village in Beiwang town, Nanwang village, Zhuge village, Qianjiao village, Guojiapo village, Qiaojiapo village in Tiantan town, Dongguopo village and Zhaishang village in Zhangzhuang town, Lijiatu village and Zhujiashan village in Xiangshuihe town, and terminates in Chejiazhuang village in Xiangshuihe town, with a total length of 24km. The formation age of geomorphological bodies was obtained. It is determined that the latest stratum dislocation event of the fault is later than 7ka, and the fault is a Holocene active fault and has the ability to generate earthquakes of magnitude 7 and above. A total of two phases of stratum dislocation events have occurred on the Fushan Fault since 17ka BP(Late Quaternary): The first-phase event E1 occurred between 17ka and 7ka BP, producing a displacement of 2.04m, the average displacement rate of the Fushan Fault is 0.20mm/a; the second-phase event E2 occurred since 7ka BP, producing a displacement of 3.93m, and the average displacement rate of the Fushan Fault is 0.56mm/a. The displacement rate of the fault has been increasing since the Late Pleistocene. The future seismic hazard of this fault is worthy of attention. This paper also uses land-based LiDAR scanning to obtain the topographic data of the fault plane on the Qiaojiapo village bedrock section of the Fushan Fault(4.5km away from the Qianjiao village section). The isotropic variogram method was used to calculate the fractal dimensions of the fault surface morphology, and the morphological weathering zone was divided, and two phases of ancient seismic events of the Fushan Fault since the Late Quaternary were determined, which are, from old to new, the first-phase event E1 which caused a co-seismic displacement of 3.18m, and the second-phase event E2 which caused a co-seismic displacement of 2.51m. Studies have shown that the bedrock fault plane fractal method is an effective method for studying ancient seismic events in the bedrock area, and its ancient seismic period division is consistent with that of the sedimentary coverage area. Finally, this paper discusses the seismogenic structure of the 1209 Fushan earthquake with magnitude of 6½, and believes that the seismogenic structure of the Fushan earthquake is most likely to be the Fushan Fault. However, due to the lack of a lower age limit and that the only upper limit age is far away from the historical earthquake time, it is necessary to conduct a more detailed investigation and research on the fault to determine whether there can be a revelation of ancient earthquake events with a younger age and comparable magnitude.
This study has greatly improved Fushan County’s risk prevention and control, and territorial planning capabilities.

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