The Chiuhsiungken fault: A candidate to trigger a hazardous earthquake in western Taiwan

The Chiuhsiungken fault located along the boundary between the Western Foothills fold-and-thrust belt and the Coastal Plain in the Chiayi-Yunlin area of Taiwan has been identified as an active thrust through geological and geomorphic investigations. Young geomorphic features provided by shortening across the Chiuhsiungken fault are well preserved and provide excellent examples to illustrate features provided by active thrust faulting. Historic seismicity records show that the deformation front in the Chiayi-Yunlin area is very active, and the fault slips at a rate of mm/yr based on tectonic geomorphic investigation. The Chiuhsiungken fault has the potential to produce large earthquakes in the future. The fault, with a length about 15 km, can be traced northward to the sinistral Kuken transfer fault and southward to near the sinistral Chuchi transfer fault. The maximum potential magnitude of an earthquake triggered by the Chiuhsiungken fault is estimated to be a Mw 6.4. However, the magnitude of the earthquake could be larger than expected if the adjacent faults rupture together with the Chiuhsiungken fault.