Surface deformation in the Himalaya and adjoining piedmont zone of the Ganga Plain, Uttarakhand, India: Determined by different radar interferometric techniques

The Himalaya and adjoining Ganga (also called Gangetic) plain are traversed by a number of neotectonically active longitudinal and transverse faults. However, the pattern and extent of present day slip rate along these faults is not yet well known. We herein present the results of our investigations directed in this direction. Surface deformations induced by active faults during a period of three years from August 2008 to August 2010 in the southern part of Uttarakhand state, India have been monitored. Multidate ENVISAT radar images of the area have been analyzed by applying the latest Interferometric Synthetic Aperture Radar (InSAR) remote sensing techniques of Persistent Scatterer Interferometry (PSI) and Atmospheric Correction InSAR (ACI) using the MODIS data. Both the PSI and ACI techniques were found capable of extracting valuable surface information despite the natural challenges of vegetal cover and mountainous terrain. The study revealed some conspicuous surface deformation patterns, which are related to active movements along some of the major faults/thrusts of the area, e.g., the Himalayan Frontal Thrust (HFT) and the transverse Garampani-Kathgodam Fault (G-KF). The G-KF acts as a segment boundary fault, dividing the study area into two distinct parts with relative subsidence in the east and uplift in the west. Based on our presumption about the G-KF, a general tectonic model of the study area has been created. The study has provided a better understanding of the active tectonics of the area.