;Located on the plate boundary between the Philippine Sea Plate and the continental margin of Eurasian Plate, Taiwan has experienced rapid convergence which leads to densely distributed active faults and frequent earthquakes. In the past ten years, for example, the 2016 Meinong earthquake occurred in southwestern Taiwan caused the most serious disaster. This study focused on analyzing eight active faults in southwestern Taiwan published by the Central Geological Survey. By integrating GPS and PS-InSAR data and implementing the three-dimensional block model method DEFNODE, this study estimated the interseismic slip rates of these faults that can be further applied to the probability seismic hazard analysis. Different form previous interseismic block models that primarily used average horizontal velocities, this study tried to incorporate PS-InSAR and vertical GPS data to model the interseismic surface uplift or subsidence caused by dip-slip faults. Results show that the GPS vertical motion was poorly fitted by block models, which may be due to unmodeled non-faulting mechanisms such as active folding. Integration of GPS and PS-InSAR observations, on the other hand, can notably affect the modeling results where velocity residuals were greatly reduced and long-term slip rates on some faults become more reasonable than the GPS-only results. This study further examined possible influence of the 2016 Meinong earthquake on interseismic slip rates of adjacent faults by dividing the GPS data into two groups: the “pre-Meinong” data from 2002 to 2015 and the “post-Meinong” data from 2016 to September 2019. Results show that slip rates of the Zuozhen, Chishan and Hengchun faults are more than 10 mm/yr faster than those before the earthquake, where the Zuozhen and Chishan faults are only 10-20 km away from the epicenter. Although whether these changes in slip rates are directly related to the Meinong event remains debated, the model results reveal possible temporal variations of fault behavior.
