The Chinshui fault is located at the western border of the Tatu terrace, west-central Taiwan. It is believed to be a continuous part of the Changhua fault extenting from the Pakua terrace in the south and also connecting to the Tachia fault developed along the Houli terrace in the north. These serial faults: the Tachia-Chinshui-Changhua fault represent the most western thrust fault system along the deformation front of western Taiwan foothill area. Photogeologic studies indicated that it is an active fault with apparent lineation and fault scarps. The seismic profiles provided by the petroleum company reveal that a standard ‘fault-bend fold’ may exist under the anticlines of the terraces. This study attempts to use the shallow reflection seismic method to map the shallow structures around the fault and to examine its relationship with the surrounding fold structures. This data may also be able to explore the generation mechanics of the terraces and the faults.
Over 50 seismic lines are distributed along the boundary between the plane and the terrace. It is surprised to find that most seismic sections are composed of flat layers even inside the area of low-level terrace. The places where the sedimentary layers start to bend are very close to the boundary of the Toukoshan formation exposed at the high-level terrace. The smoothly bending layers on the seismic sections support the model of fault-bend-fold.
