Large‐Scale Crustal Deformation, Slip‐Rate Variation, and Strain Distribution Along the Kunlun Fault (Tibet) From Sentinel‐1 InSAR Observations (2015–2020)

Abstract

AbstractLarge‐scale geodetic measurements of crustal deformation in the north‐central Tibetan Plateau are crucial for improved understanding of earthquake‐cycle processes and long‐term seismic hazard assessment. We use GPS velocities and Interferometric Synthetic Aperture Radar (InSAR) observations (2015–2020) on eight descending and eight ascending Sentinel‐1 tracks to map surface motions and their gradients for an area of over ∼2,000 km × 350 km around the Kunlun‐Manyi fault system. The derived line‐of‐sight (LOS) and 3D velocity fields demonstrate ongoing postseismic transients along the ruptured segments of the 1997 Manyi and 2001 Kokoxili earthquakes, interseismic deformation along locked fault segments, and strain accumulation on a large subsidiary fault (i.e., the Kunlun Pass fault). We use elastic dislocation and analytical postseismic deformation models constrained by our dense InSAR measurements to quantify the interseismic and postseismic contributions, which reveal the along‐fault distribution of fault slip rate and locking depth along the entire length of the fault. The results indicate that the slip rate of the Kunlun fault systematically decreases toward the west to the west of the Taiyang Lake fault. We also find that the interseismic strain accumulation rate along the main trace of the Kunlun fault is to first‐order spatially constant (0.1–0.15 microstrain/yr), except around its restraining bend. As the historically unruptured segments, especially the eastern segments (from 95°E to 101°E) of the Kunlun fault, have relatively fast slip rates and high locking depths (>15 km), they have the potential to generate large and damaging earthquakes in this region.