Multi-frame Sentinel-1 InSAR and GNSS assessment of relative line-of-sight deformation patterns in the Muş Basin, eastern Türkiye

The Muş Basin in eastern Türkiye is located in a tectonically complex region where Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) velocity fields may be affected by frame-dependent reference levels, atmospheric artifacts, orbital ramps, temporal-network differences, and line-of-sight (LOS) viewing geometry. Recent Sentinel-1 studies in Türkiye have addressed Anatolia-scale InSAR–GNSS velocity and strain-rate modelling (Weiss et al., 2020), interseismic deformation in western Türkiye (Diercks et al., 2024), and coseismic deformation associated with the 2023 Kahramanmaraş earthquake sequence (Bae et al., 2025). This study presents a frame-aware assessment of relative LOS anomaly patterns rather than an estimate of absolute vertical deformation.

Sentinel-1 data were processed with the LiCSAR/LiCSBAS time-series framework for one ascending and two descending geometries. Strict quality masking, sector-based statistics, common-pixel comparison, cumulative-displacement diagnostics, reference-normalized LOS anomaly mapping, and Global Navigation Satellite System (GNSS)-to-LOS projection with frame-specific LiCSBAS look vectors were applied.

The ascending geometry yielded the highest strict-mask valid fraction (67.27%); however, its median velocity (−11.09 mm/yr), sector time-series trend (+0.05 mm/yr), cumulative-displacement pixel-slope median (+0.23 mm/yr), and GNSS-projected LOS velocity (−3.95 ± 1.51 mm/yr) were not mutually consistent, indicating a frame-dependent reference-level mismatch. The primary descending geometry provided the most internally consistent basin-scale constraint, with a median velocity of +19.01 mm/yr, a time-series trend of +13.72 mm/yr, a cumulative-displacement slope median of +12.99 mm/yr, and a GNSS-projected LOS velocity of +4.53 ± 1.50 mm/yr.

While previous Sentinel-1 studies in Türkiye have primarily focused on Anatolia-scale velocity and strain-rate fields, regional interseismic deformation, or coseismic displacement, the present study provides a frame-aware assessment of relative LOS anomaly patterns in the Muş Basin. Accordingly, raw LOS velocity levels were not interpreted as absolute deformation rates but were evaluated in the context of reference-frame effects, viewing geometry, and GNSS constraints.