Crustal deformation analysis across Garhwal Himalaya: Part of western Himalaya using GPS observations

Abstract

Past earthquakes in the Himalayas are mainly due to tectonic activities along the thrust faults parallel to the Himalayan belt. In order to study the ongoing tectonic process, crustal deformation at a selected transect in a part of western Himalayas as well as of the Indian plate, then: are studied by the analyses of GPS data processed in a GAMIT/GLOBK platform. The data were collected from four local continuous operating reference stations (CORS), six International Global Navigation Satellite System Service (IGS) stations and five surveyed based GPS campaign stations transverse to major faults system. Results show an annual crustal motion of 19.18 mm Near Southern Tibetan Detachment (STD), 18.72 mm near Main Central Thrust (MCT), 11.93 mm near Main Boundary Thrust (MBT) and 11.53 mm near Himalayan Frontal Thrust (HFT) in India fixed reference. The present day Indian plate motion was estimated to be 55.33 mm/yr. In the study region at western Himalaya, crustal convergence of 13.83 mm/yr was observed in Dehradun-Badrinath sector in Uttarkhand. GPS sites near to north of HFT shows a westward movements and sites at peninsular India shows eastward movements suggesting possible counter clockwise rotation of the Indian plate. The annual motion across HFT varies between 0.1 and 2.0 mm, suggesting that HFT is locked in Garhwal region of western Himalaya. Insignificant movement across HFT indicates greater strain accumulation and the possibility of earthquakes in near future. The study suggests requirement of continuous monitoring of deformation across major thrusts in the Himalaya with dense network of GPS stations.