A preliminary application of ground penetrating radar to the detection of active faults along Yushu strike-slip faulted zone

GPR (Ground Penetrating Radar) has such characteristics as rapidness, wide range, great detection depth and high resolution, with no damage to the surface environment, so it seems to be quite effective in the study of active faults. Based on depicting active faults along Yushu strike-slip faulted zone, the authors employed high-resolution GPR to delineate active faults in Yushu faulted zone distributed in Longbao, Xirida and Panqionggou. The characteristic responses of electromagnetic waves were simulated on the basis of the numerical model by Finite-difference time-domain method (FDTD), and then the reflected characteristics of active faults on the GPR profiles was summarized. In this way, the GPR images are interpreted and the location, the orientation and the spatial distribution of the active fault can be accurately determined. Combined with exploratory trench cutting, GPR profile is extremely consistent with the trench section. Finally, according to the comparative study of the characteristic responses of electromagnetic waves between the GPR profiles and the trench sections, the GPR images of the earthquake epicenter are interpreted. Preliminary studies show that GPR seem to be an effective and fast technique in detecting active faults, especially in the area without clear evidence of surface rupture. It not only accurately determines the location, the orientation and the spatial distribution of the active fault but also describes the layer in the subsurface and the section outside the trench, thus providing a reference for the detection of active faults by GPR.