Slip inversion on the creeping thrust fault using geodetic data and repeating earthquakes

The Chihsang segment of Longitudinal valley fault (LVF) is characterized by both rapid surface creep and creeping at deeper depth. However, the slip inversion of the interseismic creep rate obtained using geodetic measurements does not have a good resolution at depth below 15 km, which indicates that the understanding of along-dip variation of aseismic creep is still unclear. In this study, we apply a static joint inversion that combines both geodetic data (GPS and InSAR) and seismic data (repeating earthquake) to better understand the interseismic creep. By taking advantage of the repeating sequences majorly occurring at depths below 15 km, we are able to explore more about the along-dip variation of aseismic creep. Using the geodetic and seismic data from 2007 to 2011, our slip model reveals an anti-correlation spatially between the interseismic slip and co-seismic slip of the 2003 M6 event. We also find that the mainshock of the 2003 M6 event occurred on the boundary between areas with high and low interseismic slip. This study provides a new approach of modeling the static creeping behavior, constrained using geodetic and seismic data, which might further improve the time-dependent seismic hazard.