Objective With the implementation of the integration of Beijing-Tianjin-Hebei Regions Strategy, the Sanhe City has undertaken to relocate all functions non-essential to Beijing’s role as the nation’s capital to neighboring areas. The Sanhe-Huangtuzhuang fault is a hidden fault in the north of the Sanhe City. The thickness of quaternary strata between the two sides is different greatly because of the influence of the fault. Finding out the activity of the fault since Quaternary period can provide reference for engineering construction in this area.
Methods Based on the artificial shallow seismic reflection profile, radon measurement and borehole section, this paper makes a preliminary study on its activity since the Quaternary period.
Results The artificial shallow seismic reflection profile shows that the Sanhe-Huangtuzhuang fault is an active Quaternary fault and controls the deposition of Quaternary. The up-breakpoint of the fault is about 25~30 m away from the surface. By comparing S13 and S12 holes on both sides of the fault with Quaternary standard borehole S9, the Quaternary stratigraphic framework of the two boreholes are established.
Conclusions According to the comparison of deposition rates and marker beds of the two boreholes in different stages of Quaternary, it is speculated that the Sanhe-Huangtuzhuang fault has been active since the Pliocene, the fault activity increased in the Early Pleistocene, and gradually weakened or even inactive in the late Middle Pleistocene-Late Pleistocene. According to the previous research results on fault activity and seismogenic laws in the eastern section of Zhangjiakou-Bohai tectonic belt, we conclude that the Sanhe-Huangtuzhuang fault has been inactive since Holocene, and the possibility of inducing moderate earthquake is low. This research can provide geological foundations for the spatial planning and earthquake prevention and disaster reduction of Sanhe City.
DownLoad: