An active fault in southern Taiwan detected using shallow seismics and ground penetration radar

Abstract

We conducted high-resolution shallow seismic exploration and ground penetrating radar (GPR) exploration to assess the earthquake hazard along the speculated north-south striking Chaujou Fault that is along the mountain foot at the western edge of the Central Range in the southern tip of Taiwan. Shallow seismic and GPR survey lines are approximately eastwest oriented, perpendicular to the speculated fault. All these survey lines run across the speculated fault. A fault plane of an 50° east-dipping angle is interpreted using shallow seismic profiles and one GPR profile. The interpreted fault locations are consistent with the scarp on the earth?s surface with an error of only a few meters, indicating that the scarp marks the Chaujou Fault?s surface location. The GPR profile even shows fault planes within a few meters depth, indicating fault rupturing within the past centuries. As Taiwan has humid climate with high erosion and deposition rate, these evidences imply that the Chaujou Fault really exists and is an active fault, that it has been displaced within the past centuries, and that it is a potential earthquake-inducing mechanism.