Abstract Pingtong Town locates just over the fractured zone of the Wenchuan Ms8.0 earthquake and the damage at the surface is very serious. The observational line with its middle point at an earthquake exploration trough crosses the fractured zone, and stretches in NW-SE direction, whose total length is about 400 m. The observational results show that the fault zone trapped waves from the fractured zone of Wenchuan Ms 8.0 earthquake were observed. That indicates that there is a great difference in physical property between the media inside and outside the fault zone. The predominant frequency of the fault zone trapped waves is about 3-4 Hz. It is stronger near the exploration trough. The width of the fault zone in the crust in this region is estimated to be 200 m. Furthermore, from some records it can be seen that the waveforms between the two sides of the trough are quite different and the arrival times of the S waves are also different. The sudden variation point of the waveforms is consistent with the boundary of the uplift at the surface.
