Towards quantifying the relative tectonic activity in the Trans-Yamuna segment of NW Himalaya

Abstract

Owing to the increased availability of high-resolution satellite data and the rapid development of Geographic Information System (GIS) technology, the mapping of active faults and quantification of tectonic activity in inaccessible regions has exceedingly improved. We examined the tectonic activity in the Trans-Yamuna region of the NW Himalaya using geomorphic indices derived from a Digital Elevation Model (DEM). In addition, this study evaluates the sensitivity of four space-borne Digital Elevation Models (DEMs) with respect to TAN DEM-X (TerraSAR-X add-on for Digital Elevation Measurements). The Cartosat DEM, generated with a spatial resolution of 5 meters using state-of-the-art methods, demonstrated a reliable representation of topography. Geomorphic indices such as Asymmetry Factor (AF), Transverse Topography (TT), Hypsometric Integral (HI), Valley Floor width (Vf), Stream-length gradient index (SL), and Normalised steepness index (ksn) were computed for 41 sub-watersheds to determine the degree of tectonic activity. We infer that majority of the region is tectonically active, with upliftment continuing to occur in the north of the Main Boundary Thrust (MBT). Furthermore, the existence of mapped active faults north of the MBT further substantiates the fact that strain release is not only concentrated in the frontal Himalaya, but is distributed over a broader area above the decollement.