A Multidecadal Catalog of Normal-Faulting Earthquakes Across the Tibetan Plateau Derived From InSAR and Body-Waveform Modeling: Insights Into the Plateau's Extensional Tectonics and Dynamics

Normal-faulting structures are believed to play a significant role in accommodating large-scale continental extension across the Tibetan Plateau. However, the fine-scale details of active tectonic structures in this region and their relationships with plateau deformation patterns remain poorly constrained. To better understand the extensional tectonics of the plateau, we compile a multidecadal catalog of normal-faulting earthquakes, including 40 Mw ≥ 5 events since 1976, using interferometric synthetic aperture radar (InSAR) analysis and global synthetic body-waveform modeling (gWFM). Most events occurred along N–S-trending fault planes at depths shallower than 10 ± 2 km and are characterized by a single, roughly circular asperity, with an average rupture width-to-length ratio of 0.8. Approximately 80% of events have dip angles within 35–65° (±10°), although one potential low-angle (<35°) event and several high-angle (>65°) events are also identified. The spatial distribution of dip angles does not support the proposed extensional patterns, such as the west–east sequential collapse model (dip angles increase from west to east) or the central axially symmetric model (dip angles decrease from the middle at 87°E to the two sides). We find that most events occurred at elevations above 5,000 m, corresponding to regions of positive dilation strain. Approximately 82% ± 7% of the regional geodetic dilation strain can be accounted for by the seismic moment release of normal-faulting events. Finally, normal-faulting events are confined to a region bounded by the southern margin of the Indian indenter and the Manyi–Kunlun fault. They are distributed mainly across the interior of the plateau, away from the eastern and western tectonic syntaxes.