Interseismic Coupling, Asperity Distribution, and Earthquake Potential on Major Faults in Southeastern Tibet.

Southeastern (SE) Tibet is one of the most seismically active regions in mainland China, but the spatial distribution of interseismic coupling that quantifies seismic hazard is unknown along most major faults. In this study, we constructed an elastic block model to invert Global Positioning System data for slip rates and locking coefficients along 20 major faults in SE Tibet. Our results identify 27 strongly coupled fault segments with locking coefficients >0.5, defined as potential seismogenic asperities, extending laterally for 36–330 km. Quantitative calculations of seismic moment budgets on these seismogenic asperities indicate that they are capable of generating Mw 6.4–7.7 earthquakes in the next few decades, of which the Anninghe, Daliangshan and Red River faults have the potential for Mw ≥ 7.5 earthquakes. The interseismic coupling model provides a component for probabilistic analysis of future seismic hazards in densely populated Southwest China. Plain Language Summary: In the period between earthquakes, crustal faults are either partially to fully stuck or slipping freely. In the former case, plate movement can cause a buildup of energy on the fault plane and eventually be released through earthquakes. Using Global Positioning System (GPS) to measure the movement of the Earth's surface, we can use models of crustal deformation to identify where and how quickly faults are accumulating energy and then make reasonable predictions about the locations and magnitudes of future earthquakes. Based on the above principles, in this study, we use GPS measurements to suggest the locations and magnitudes of potential earthquakes on 20 major faults in southeast Tibet, which includes most of the Sichuan and Yunnan provinces in southwestern China. We find that 27 fault segments with lengths of 36–330 km are stuck to some degree and accumulating energy. Currently, the accumulated energy can produce earthquakes of Mw 6.4–7.7, highlighting the severity of earthquake hazards in Southwest China. Key Points: We obtained a unified interseismic coupling model for 20 major fault systems in southeastern TibetWe identify 27 seismogenic asperities with locking coefficients >0.5 that could host Mw 6.4–7.7 earthquakesThe interseismic coupling model provides a component for probabilistic analysis of future seismic hazards in Southwest China [ABSTRACT FROM AUTHOR]