Neotectonics of the Western Suleiman Fold Belt, Pakistan: Evidence for Bookshelf Faulting

The Suleiman Fold-Thrust Belt represents an active deformational front at the western margin of the Indian plate and has been a locus of major earthquakes. This study focuses on the western part of the Suleiman Fold-Thrust Belt that comprises two parallel NW-SE oriented faults: Harnai Fault and Karahi Fault. These faults have known thrust components; however, there remains uncertainty about the lateral component of motion. This work presents the new observation of surface deformation using the Small Baseline Subset (SBAS), Interferometric Synthetic Aperture Radar (InSAR) technique on Sentinel-1A datasets to decompose displacement into the vertical and horizontal components employing ascending and descending track geometries. The subsurface structural geometry of this area was assessed using 2D seismic and well data. In addition, geomorphic indices were calculated to assess the relative tectonic activity of the area. InSAR results show that the Karahi Fault has a similar to 15 mm right-lateral movement for descending and similar to 10 mm/for ascending path geometries. The Harnai Fault does not show any lateral movement. Seismic data are in agreement with the InSAR results suggesting that the Harnai Fault is a blind thrust. This work indicates that the block between these two faults displays a clockwise rotation that creates the bookshelf model.

Automated summary

The study focused on the western part of the Suleiman Fold-Thrust Belt, analyzing surface deformation using InSAR techniques and seismic data to assess the subsurface structural geometry. It found that the Karahi Fault exhibits right-lateral movement, while the Harnai Fault is identified as a blind thrust. The area between these two faults displays a clockwise rotation, forming a bookshelf model.