Abstract:

The composite profile of some geophysical exploration methods, including controlled source audio-frequency magnetotellurice method, shallow seismic and radon methods, was used to pinpoint the position of Baifu-Baishan section of Nankou-Sunhe fault. By studying the borehole sedimentary facies and the magnetostragigraphy characteristics, this paper discussed the activity of Nankou-Sunhe fault in Quaternary. The results show that the position displacement of the main fault is from 500 to 800 meters along NE direction compared with previous reports. The result of two boreholes in Baishan shows that the fault^,s vertical rate is 0.12 mm/a, 0.58 mm/a and 0.31 mm/a in Middle Pleistocene, Late Pleistocene and Holocene, respectively. The activity of the fault is weak to strong, and then weak. Therefore, combined with borehole profiles, the comprehensive geophysical profile can pinpoint the location of buried active faults in cities, and can be used to analysis the faults^,characteristics, providing valuable information for taking effective preventive measures to reduce the disaster in urban areas and to protect the lives and properties of people.

Key words: buried fault, geophysical exploration, join profile, activity rate, Nankou-Sunhe fault