Enhanced Interseismic Coupling Due to Stress Interactions May Contribute to the Cascading Rupture Across the Branching Kunlun Pass Fault During the 2001 Mw 7.8 Kokoxili Earthquake

Abstract Large continental earthquakes often involve cascading ruptures across branching faults, thus increasing the magnitude of the rupture, but the factors controlling such rupture patterns remain unresolved. Here, we use a physically plausible model and the Interferometric Synthetic Aperture Radar (InSAR) data to show the coupling distribution and stress interactions during 2015–2020 for the triple junction of the Kusaihu, Kunlun Pass, and Xidatan faults in northern Tibet. The postearthquake relocked Kunlun Pass fault, which ruptured in the 2001 Mw 7.8 Kokoxili earthquake, undergoes strong stress interactions from the nearby, interseismically locked Xidatan fault. The shear stressing rate due to stress interactions is 2–3 times larger than that due to the self-locking, which spatially correlates with the slipped area during the Kokoxili earthquake. Interferometric Synthetic Aperture Radar- and GPS-derived coupling models are consistent for such stress interactions. We argue that the enhanced stress build-up on the branching Kunlun fault may have contributed to its cascading ruptures in the 2001 Kokoxili earthquake.