Frequency-Dependent Bilateral Rupture of the 2024 Mw 7.1 Wushi Earthquake, NW China: Insights from InSAR, Seismic Imaging, and Aftershock Relocation

Abstract The 2024 Mw 7.1 Wushi earthquake at the Tianshan-Tarim collisional boundary in northwest China was characterized by a frequency-dependent bilateral rupture process. By integrating Differential Interferometric Synthetic Aperture Radar (D-InSAR), finite-fault inversion (FFI), backprojection (BP), and aftershock relocation, we unravel the spatiotemporal complexity of rupture across distinct frequency bands. D-InSAR resolved two main asperities on the reactivated Kuqi-Maidan fault system, with maximum coseismic slips of 1.61 m (east-northeast direction) and 2.19 m (west-southwest direction). FFI of near-field microelectromechanical systems data (<0.5 Hz) revealed temporally staggered earthquake rupture initiation: the east-northeast-directed rupture nucleated immediately, peaking at 5–6 s, whereas the west-southwest-directed rupture commenced ∼6 s later with a slower rupture velocity. BP analysis of S-wave radiation demonstrated frequency-dependent rupture directivity: high-frequency (>1 Hz) rupture branch propagated east-northeast with a velocity of ∼3.45 km/s into the deeper Tianshan orogenic structures, contrasting with west-southwest-oriented low-frequency (0.5–1 Hz) front (∼3.05 km/s) migrating toward shallow structural depths. Relocated aftershocks confirm alignment of clusters with rupture segments corresponding to the asperities. Our multidisciplinary approach reconciles static and kinematic models, providing new insights into intracontinental earthquake mechanisms in active collision settings.