The application of shallow seismic and high-density electrical methods in fault zone detection：Taking the western edge fault of the Maoyaba Basin in Litang, western Sichuan as an example

The western edge fault of the Maoyaba Basin, a branch of the Litang fault zone in western Sichuan, is the western boundary fault controlling the Great Maoyaba Basin. There have been no reports on its geometric distribution and deep structure. This article uses high-density electrical method and shallow seismic exploration technology to conduct geophysical exploration on the northern and southern sections of the western edge fault of the Maoyaba Basin, respectively. The response characteristics of the western edge fault of the Maoyaba Basin revealed by the high-density electrical method and shallow seismic exploration profiles are analyzed. The western edge fault of the Maoyaba Basin shows lateral displacement of the marker layer on the shallow seismic reflection profile, with the presence of fault diffraction waves and other phenomena. The tomographic inversion velocity profile reflects significant changes in the lateral velocity on both sides of the fault, suggesting that the depth of the upper breakpoint is shallower than 15 m. The low resistance strip characteristics on the apparent resistivity profile inverted by the high-density electrical method are preliminarily determined by combining field investigation and regional geological data to determine the production of the fault, shape, geometric structure, and planar layout. Advantages, disadvantages, and application prerequisites of the two geophysical methods in active fault detection are also explored in this article. Based on similar cases domestically and internationally, a combination of multiple methods is proposed to more effectively detect fault structures.