Spatiotemporal evolution of seismic slip of the 31 October 2013 Ruisui, Taiwan, earthquake

In this study, coseismic and postseismic deformation following the October 31, 2013 M 6.4 earthquake in eastern Taiwan is investigated using InSAR and GPS measurements. The InSAR data includes a pair of ascending and descending SAR data from Radarsat-II satellite covering the mainshock. The GPS measurements span the earthquake and up to 340 days after the event. The geodetic measurements of coseismic deformation are inverted to determine fault geometry and slip distribution. GPS time series data are analyzed by Principal Component Analysis based Inversion Method (PCAIM) to derive space and time distribution of postseismic fault slip. The main coseismic slip in the best fitting oblique-thrust dislocation shows two clear asperities: a small asperity at a depth of about 5 km with a maximum slip of 0.6 m and a larger asperity between depths of 15-25 km with maximum slip of 1 m. There is little slip above 5 km, suggesting the presence of active subsurface (blind) faulting under the Central Range. The mainshock is followed by widespread frictional afterslip on one patch which is localized close to the deepest coseismic asperity.