China Institute of Disaster Prevention, Sanhe, China.
Hebei Key Laboratory of Earthquake Dynamics, Sanhe, China.
PLoS One. 2022 Oct 14;17(10):e0275436. doi: 10.1371/journal.pone.0275436. eCollection 2022.
Beijing plain is a strong earthquake tectonic area in China. There was a Sanhe-Pinggu earthquake with Ms8 that happened in1679. The seismogenic fault of this earthquake is called Xiadian fault. Our work found fault with a similar strike and opposite dip in the west of the Xiadian fault, which is called the Xiadian west fault in this paper. Six shallow seismic profiles have been constructed to determine the location of the fault in Sanhe city, and the late Quaternary activity of the fault is studied with the method of combined drilling, magnetic susceptibility logging, and luminescence dating. The results of shallow seismic exploration show that the fault is zigzag and generally strikes NE and inclines NW. According to the core histogram and logging curves of ten boreholes and eight effective dating data, the buried depth of the upper breakpoint of the concealed fault is about 12 m, which dislocates the late Pleistocene strata. The effective dating result of this set of strata is 36.52 ±5.39 ka. The vertical slip rate has been about 0.075± 0.023 mm/a since the late Pleistocene and about 0.058 ± 0.030 mm/a since the late period of the late Pleistocene. It can be inferred that the Xiadian west fault is probably a part of the seismogenic structure of the Sanhe-Pinggu Ms8 earthquake that happened in 1679. In a broad sense, the Xiadian fault zone is likely to extend to the southwest along the Xiadian west fault.
北京平原是中国的一个强烈地震构造区。1679 年发生了一次 8 级的三河-平谷地震。这次地震的发震断层称为下店断层。我们的工作在该断层的西部发现了一条具有相似走向和相反倾向的断层，本文将其称为下店西断层。为了确定三河市的断层位置，共布置了 6 条浅层地震剖面，并采用钻探、磁化率测井和发光测年相结合的方法研究了断层的晚第四纪活动性。浅层地震勘探结果表明，该断层呈之字形，总体走向为 NE，倾向 NW。根据 10 个钻孔的岩芯柱状图和测井曲线以及 8 个有效测年数据，隐伏断层的上断点埋深约为 12 m，错断了晚更新世地层。这套地层的有效测年结果为 36.52±5.39ka。自晚更新世以来，该套地层的垂直滑动速率约为 0.075±0.023mm/a，晚更新世晚期以来约为 0.058±0.030mm/a。可以推断，下店西断层可能是 1679 年三河-平谷 8 级地震的发震构造之一。广义上讲，下店断层带可能沿下店西断层向西南延伸。
