Bayesian Inference of Fault Slip and Coupling Along the Tuosuo Lake Segment of the Kunlun Fault, China

Abstract

Integrating newly-processed Interferometric Synthetic Aperture Radar (InSAR) and available Global Positioning System (GPS) data, we obtained a dense interseismic velocity field across the Tuosuo Lake segment of the Kunlun fault. Using a Bayesian approach, we obtained the spatial distribution of fault slip and coupling. The slip rate below the locking depth, which represents contemporary steady-state faulting, demonstrates an overall decrease, and decreases non-monotonically toward the eastern fault tip in the range of ∼5–11 mm/a. Two strongly locked zones are identified, extending 100–120 km along-strike and being separated by narrow sections of moderate coupling. These locked zones were likely ruptured during the 1937 M 7.5 Huashixia earthquake. The estimated moment accumulation rate provides a recurrence time of 428 ± 57 years for an earthquake similar to the 1937 event. The Maduo Mw 7.3 earthquake on 21 May 2021 imposed stress loading on the locked zones, equivalent to tectonic loading of ∼10 years, implying increased seismic hazard along the Kunlun fault.