Bettinelli, Pierre and Avouac, Jean-Philippe and Flouzat, Mireille and Jouanne, François and Bollinger, Laurent and Willis, Pascal and Chitrakar, Gyani Raja (2006) Plate Motion of India and Interseismic Strain in the Nepal Himalaya from GPS and DORIS Measurements. Journal of Geodesy, 80 (8-11). pp. 567-589. ISSN 0949-7714. http://resolver.caltech.edu/CaltechAUTHORS:20101117-134557761
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We analyse geodetically estimated deformation across the Nepal Himalaya in order to determine the geodetic rate of shortening between Southern Tibet and India, previously proposed to range from 12 to 21 mm yr^(−1). The dataset includes spirit-levelling data along a road going from the Indian to the Tibetan border across Central Nepal, data from the DORIS station on Everest, which has been analysed since 1993, GPS campaign measurements from surveys carried on between 1995 and 2001, as well as data from continuous GPS stations along a transect at the logitude of Kathmandu operated continuously since 1997. The GPS data were processed in International Terrestrial Reference Frame 2000 (ITRF2000), together with the data from 20 International GNSS Service (IGS) stations and then combined using quasi observation combination analysis (QOCA). Finally, spatially complementary velocities at stations in Southern Tibet, initially determined in ITRF97, were expressed in ITRF2000. After analysing previous studies by different authors, we determined the pole of rotation of the Indian tectonic plate to be located in ITRF2000 at 51.409±1.560°N and−10.915± 5.556°E, with an angular velocity of 0.483±0.015°. Myr^(−1). Internal deformation of India is found to be small, corresponding to less than about 2 mm yr^(−1) of baseline change between Southern India and the Himalayan piedmont. Based on an elastic dislocation model of interseismic strain and taking into account the uncertainty on India plate motion, the mean convergence rate across Central and Eastern Nepal is estimated to 19 ± 2.5 mm yr^(−1), (at the 67% confidence level). The main himalayan thrust (MHT) fault was found to be locked from the surface to a depth of about 20km over a width of about 115 km. In these regions, the model parameters are well constrained, thanks to the long and continuous time-series from the permanent GPS as well as DORIS data. Further west, a convergence rate of 13.4 ± 5 mm yr^(−1), as well as a fault zone, locked over 150 km, are proposed. The slight discrepancy between the geologically estimated deformation rate of 21 ± 1.5 mm yr^(−1) and the 19 ± 2.5 mm yr^(−1) geodetic rate in Central and Eastern Nepal, as well as the lower geodetic rate in Western Nepal compared to Eastern Nepal, places bounds on possible temporal variations of the pattern and rate of strain in the period between large earthquakes in this region.
|Additional Information:||© 2006 Springer-Verlag. Received: 4 November 2005. Accepted: 27 January 2006. We are grateful to Jeff Freymueller and two anonymous reviewers for most helpful suggestions and comments, and to Will Featherstone for his careful editorial review of the manuscript. We also thank Jeff Genrich for useful comments and suggestions. We are most grateful to all the people who have contributed to the data acquisition, in particular M. Thankauri, B. Chaudhary, B. Kaffle (DMG, Kathmandu); J.B. De Chabalier (Institut de Physique du Globe de Paris (IPGP)), J. Lavé (Laboratoire de Géophysique Interne et de Tectonophysique (LGIT)), R. Cattin (Ecole Normale Supérieure (ENS)). T. Héritier, J. Rouault, and S. Carré, all at Commissariat à l’Energie Atomique/Département Analyse Surveillance Environnement (CEA/ DASE), have greatly contributed to this project. We thank Roger Bilham for making available the GPS campaign data collected by him and his colleagues at the Cooperative Institute for Research in Environmental Sciences (CIRES, University of Colorado). This study benefited also from the GPS campaign data collected during the Centre National de la Recherche Scientifique/Institut National des Sciences de l’Univers (CNRS/INSU) program IDYL-HIM. The realisation of the DORIS time-series was carried out at the Jet Propulsion Laboratory (JPL) under a contract with the National Aeronautics and Space Administration (NASA). This work was supported by the CEA, the CNRS IDYL-Him project and the Betty and Gordon Moore Foundation. This is Caltech Tectonics Observatory contribution number 32. The maps in this paper were generated using the public-domain Generic Mapping Tools (GMT) software (Wessel and Smith 2001).|
|Group:||Caltech Tectonics Observatory, Caltech Tectonics Observatory. Indo-Asian Collision Zone|
|Subject Keywords:||GPS; DORIS; interseismic deformation; tectonic plate convergence; Himalayas of Nepal|
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|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||17 Nov 2010 22:05|
|Last Modified:||26 Dec 2012 12:39|
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