关键词: 普渡河断裂, 电阻率层析成像, 电性结构

Abstract: Yuxi basin is one of the potential earthquake risk areas with high seismic frequency and intensity in Yunnan Province. In order to set up the "standard" structure model to be applied directly in earthquake prevention and disaster reduction,we used electrical resistivity tomography(ERT)to detect the electrical structure of mountain-basin transition zone in Yuxi basin and Pudu River Fault which is buried in and goes through the western margin under the support of the Special Project for the Fundamental R&D of Institute of Geophysics,China Earthquake Administration. In data acquisition,6 ERT measuring lines,as an important supplement to the seismic reflection survey,were designed to control the fault,and Wenner α arrays were used,with the electrode spacing of 6m,maximum depth factor of 30～75 and the electrode number of each array being 112～288.Our results indicate that Pudu River Fault in Yuxi basin consists of two NNE-striking branches,the east branch and the west branch. From south to north,the width of the fault zone becomes wider from Wenquan town to Heicun Village at first and then becomes narrower through Lianchi and Meiyuancun Village to Yukun Iron & Steel Co. Ltd. Its hanging wall is a low resistivity fracture zone,while its footwall appears as a homogeneous high-resistivity zone. The east branch (F_1-2) has an apparent dip direction of SE/S near and to the north of Meiyuancun Village and of NW near and to the south of Lianchi Primary School,with the apparent dip angle of 56°～73°,while the west branch(F_1-1) has an apparent dip direction of SE/E/S and the apparent dip angle of 38°～66°.The seismic results showed that both of the east and west branches of Pudu River Fault have the apparent dip direction of SE/E and apparent dip angle of 75°～80° in Yuxi basin(He et al., 2012),which are slightly different from our results.

Key words: Pudu River Fault, electrical resistivity tomography, electrical structure