HR: 08:00h
AN: G41A-01    [Abstracts]
TI: InSAR Observations of low Slip Rates on the Major Faults of Western Tibet
AU: * Wright, T J
EM: tim.wright@earth.ox.ac.uk
AF: COMET, Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Parsons, B
EM: barry@earth.ox.ac.uk
AF: COMET, Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR United Kingdom
AU: England, P C
EM: philip@earth.ox.ac.uk
AF: COMET, Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Fielding, E J
EM: Eric.J.Fielding@jpl.nasa.gov
AF: COMET, Department of Earth Sciences, University of Cambridge, Bullard Labs Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Fielding, E J
EM: Eric.J.Fielding@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena, CA 91109-8099 United States
AB: Two contrasting views of the active deformation of Asia dominate the debate about how continents deform. In the first, deformation is primarily localized on a few major faults separating plate-like crustal blocks. In the second, deformation is distributed throughout the continental lithosphere. In the first model, western Tibet is being extruded eastwards between the major faults bounding the region. Surface displacement measurements across the western Tibetan plateau using satellite radar interferometry (InSAR) indicate that slip rates on the Karakoram and Altyn Tagh faults are lower than would be expected for the extrusion model and suggest a significant amount of internal deformation in Tibet. To determine slip rates we used 5 independent, 500-km-long strips of radar data acquired by the ERS-1 and ERS-2 satellites between 1992 and 1999. The data span the entire width of the western plateau, from the Tarim basin in the north to just north of the Himalayas. Atmospheric disturbances were observed to be low on the plateau. The interferograms cover time intervals of between 1.9 and 3.6 years, and were stacked to reduce the impact of atmospheric and topographic errors. We solved for slip rates assuming surface displacements are equivalent to those caused by an infinitely long screw dislocation in an elastic half space, and use a locking depth of 10~km. To account for data uncertainties, we used the Monte Carlo simulation of correlated noise. The right-lateral slip rate of the Karakoram Fault was found to be in the range 1$\pm$3~mm/yr (upper bound of 7~mm/yr at 95% confidence level); the left-lateral slip rate of the Altyn Tagh Fault was found to be 5$\pm$5~mm/yr. These estimates disagree with some geologic measures of slip rates but agree with results from other geodetic data.
DE: 9320 Asia
DE: 8110 Continental tectonics--general (0905)
DE: 1208 Crustal movements--intraplate (8110)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting