Coseismic and Postseismic Slip Analysis of the 2024 <i>M</i>w 7.0 Wushi Earthquake: Insights From InSAR Observations and Slip Inversion

Analysis of fault slip behavior is crucial for assessing regional seismic hazards. This study employs Sentinel-1 SAR data to investigate the coseismic and postseismic deformation associated with the 2024 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i>w 7.0 Wushi earthquake using Interferometric Synthetic Aperture Radar (InSAR) technique. Through multi-temporal InSAR analysis, we reconstructed the coseismic slip distribution and revealed the spatiotemporal evolution of postseismic slip. The coseismic rupture released a seismic moment of 3.65<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\times 10^{19}$</tex-math></inline-formula> N<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\cdot$</tex-math></inline-formula> m (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i>w 7.0) with maximum slip of 2.3m at 12km depth. Coseismic Coulomb stress changes triggered the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> 5.6 aftershock on January 30, 2024, with surface rupture observed. Postseismic deformation exhibits coupled afterslip-aftershock mechanisms, showing asymmetric line of sight (LOS) displacement with maximum uplift of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 20cm (ascending track) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 15cm subsidence superimposed on 20cm uplift (descending track). Time-series analysis reveals a two-phase decay pattern: rapid deformation at 20cm/month during the initial two weeks, decaying to 0.5cm/month over subsequent four months. The friction parameter (0.001 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&lt; $</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$a - b$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&lt; $</tex-math></inline-formula> 0.003) indicates velocity-strengthening behavior in the Maidan fault's postseismic slip zone, suggesting stable slip characteristics. However, the relatively low friction coefficient still warrants attention to long-term fault motion and strain accumulation. This study provides new observational constraints for understanding postseismic deformation mechanisms and frictional properties in the South Tianshan orogenic belt.