GPS-derived deformation rates in northwestern Himalaya and Ladakh
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Deformation rates derived from GPS measurements made at two continuously operating stations at Leh (34.1°N, 77.6°E) and Hanle (32.7°N, 78.9°E), and eight campaign sites in the trans-Himalayan Ladakh spanning 11 years (1997–2008), provide a clear picture of the kinematics of this region as well as the convergence rate across northwestern Himalaya. All the Ladakh sites move 32–34 mm/year NE in the ITRF2005 reference frame, and their relative velocities are 13–16 mm/year SW in the Indian reference frame and ~19 mm/year W with reference to the Lhasa IGS station in southeastern Tibet. The results indicate that there is no statistically significant deformation in the 200-km stretch between the continuous sites Leh and Hanle as well as between Leh and Nubra valley sites along the Karakoram fault, whereas the sites in and around the splayed Karakoram fault region indicate surface deformation of 2.5 mm/year. Campaign sites along the Karakoram fault zone indicate a fault parallel surface motion of 1.4–2.5 mm/year in the Tangste and western Panamik segment of the Karakoram fault, which quantifies the best possible GPS-derived dextral slip rate of 3 mm/year along this fault during this 11-year period. Baselines of Ladakh sites show convergence rates of 15–18 mm/year with respect to south India and 12–15 mm/year with respect to Delhi in north India and Almora in the Himalaya ~400 km north-northeast of Delhi. These constitute an arc normal convergence of 12–15 mm/year across the western Himalaya, which is consistent with arc normal convergence all along the Himalayan arc from west to east. Baseline extension rates of 14–16 mm/year between Lhasa and Ladakh sites are consistent with the east–west extension rate of Tibetan Plateau.
KeywordsGlobal positioning system (GPS) Ladakh Himalaya Karakoram fault Surface deformation India
We acknowledge the grant of Department of Science and Technology, DST (ESS/CA/A9-14 IRHPA) and Ministry of Earth Sciences, MoES (MoES/P.O./Seismo/GPS/36/05), Government of India, to establish permanent GPS stations and to carry out regional GPS surveys to rigorously constrain the complex deformation regime in the Ladakh region. We acknowledge the support received from Indian Institute of Astrophysics, Ladakh division, for the continuous support in operation and maintenance of the Leh and Hanle permanent GPS sites. We thank Director, G.B. Pant Institute of Himalayan Environment and Development, for his support in operation of Almora permanent GPS station. We acknowledge the support of SIC, C-MMACS, for the GPS programme. We acknowledge the technical help of Mr. Shrungehswar in the preparation of the manuscript. Our sincere thanks to the reviews on this paper, which helped in vastly improving the quality of this manuscript.
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