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Continental collision at the western boundary of the Indian continent formed the tectonically complex transpressional zones of the Sulaiman Fold and Thrust (SFT) belt. Seismic hazard in the SFT is considered very high due to strong transpressional movement and documented active seismicity. Here, we study SAR time series of Sentinel-1A through LicSBAS to estimate the coseismic crustal deformation along with the inter-seismic, and post-seismic movement caused by the 2021 M 5.9 Harnai earthquake in the central SFT belt. The line-of-sight (LOS) displacement amounts to ~55 and ~65 mm for ascending and descending interferograms respectively, due to thrust-dominated slip over the NW-SE trending fault. We invert the LOS displacement through the Bayesian inversion approach. The inverted InSAR measurements fit well with USGS and ISC model parameters. A simplified fault model shows a dip of 22°, strike of 282°, length of 10 km, and width of 11 km. We perform kinematic inversions to determine the slip on complex fault geometries such as double fault-bend fold (décollement-ramp-décollement) and fault-propagation fold (décollement-ramp) systems. We find post-seismic movement on the fault, however, at this stage, we are not conclusive to interpret the signal as after-slip or viscoelastic relaxation. The double fault-bend structures are commonly observed in the frontal and central SFT zone. Previous work on the frontal zone of SFT indicates the presence of décollement that branches into a shallow ramp (Javed et al. 2022, GRL) matching geological and seismic observations in the SFT belt.&nbsp, The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Oblique convergence across Tibet leads to slip partitioning with the coexistence of strike-slip, normal and thrust in major fault systems. Both transform and convergent components of deformation are responsible for significant seismic hazard. However, fault interactions and present-day deformation related to thrust faults are poorly explored in current models of interseismic deformation. Here, we use SAR interferometry and GPS data to investigate slip partitioning between the Haiyuan fault system and the Qilian Shan restraining bend at the north- eastern active margin of the Tibetan plateau. The objectives are both methodological (extracting a small deformation signal in mountainous areas by InSAR) and thematic (understanding the present-day kinematics along this complex fault system). For InSAR, we use the most recent developments of our Small Baselines interferometric chain NSBAS (that takes into account, in particular, atmospheric and DEM delays corrections before un- wrapping). We compute and analyze time series of interferograms built from the complete Envisat data archive over track 104 in between 2003 and 2010. We then model the velocity field by oblique slip on a deep crustal decollement connecting the roots of the major Haiyuan and Gulang left-lateral faults and the Qilian Shan thrust. Using this geometry, we determine a horizontal shortening rate of 4+- 2 mm/yr and fault-parallel component of 9+- 2 mm/yr across the whole fault system, with different partitioning west and east of the Tianzhu pull-apart basin. Our simple model gives a quantitative understanding of how crustal deformation is accommodated by the various branches of this thrust/strike-slip fault system and shows that the complexity of the Haiyuan fault system may be accounted for by partitioning, laterally and at depth, of the more simple block motion.