Late Quaternary Active Borehole Joint Profile Detection of Internal Faults in Shulu Sag of Xingtai Seismic Zone in 1966
NAN Bohan
LI Yanbao
CHEN Lichun
Cao Jun
PAN Rongqing
Abstract：From March 8 to 29,1966,there were five earthquakes above 6 magnitude in Xingtai area,including Ningjin 7.2 earthquake,which caused more than 8000 deaths.The Xingtai earthquake swarm occurred in the Shulu Depression in the south-central North China Plain.Previous data suggest that the boundary and internal faults of Shulu Depression are not active in the late Quaternary.The seismogenic structure of the 1966 Xingtai earthquake may be a hidden deep strike-slip fault,which is not related to the shallow pre-existing faults.The recent shallow seismic exploration work carried out in the Shulu Depression and its vicinity reveals that faults with shallow burial depth of upper breakpoints may be developed inside the Depression.Based on the results of the latest shallow seismic exploration work,this paper uses the borehole joint profile detection method,combined with the chronology test,to detect the breakpoints revealed by the shallow exploration in detail and analyze the age of fault activity.The detection results reveal that a steeply dipping active fault since the late Pleistocene—Xinhexi fault is also developed on the west side of the Xinhe fault on the eastern boundary of the Shulu Depression,which may be connected up and down with the deep steeply dipping strike-slip fault revealed by the early detection data.The detection results provide key information for the analysis and discussion of the seismogenic structure of the 1966 Xingtai M7.2 earthquake.
Keywords：1966 Xingtai M7.2 earthquakeShulu DepressionBorehole joint profile detectionActive fractureNorth China Plain
Publication Date：2025-12-30
Online Publishing Date：2025-12-15(First online date of this platform, not the publication date of the document)
Pages：9( 8-16 )