Based on paleo-reconstructions of tectonic evolution of Taiwan, on the style of deformation across the Taiwan mountain ranges, on global travel-time tomography beneath Taiwan and on the characteristics of the Chi-Chi earthquake, I Propose that the last M7.6 earthquake is a "subduction earthquake" which has ruptured a segment of the plate interface between the Eurasia and the Philippine Sea. Considering this event as an interface thrust earthquake, I propose to guide the future investigations of the Taiwan Foothills with such view including ultra-deep drilling (about 5-8 km) through the ruptured fault, down-holw permanent monitoring, systematic paleoseismic studies across active faults and numerical modeling of elastic deformation of Taiwan coupled with GPS observations. The aim of these studies being the determination of the distribution, recurrence and magnitudes of earthquakes in the western part of Taiwan.