HR: 08:20h
AN: G31D-02 INVITED     [Abstracts]
TI: Surface displacements and source parameters of the 2003 Bam (Iran) earthquake from Envisat ASAR imagery
AU: * Funning, G J
EM: garethf@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: Wright, T J
EM: timw@earth.ox.ac.uk
AF: COMET, Department of Earth Sciences University of Oxford Parks Road, Oxford, OX1 3PR United Kingdom
AU: Jackson, J
EM: jackson@esc.cam.ac.uk
AF: COMET, Bullard Laboratories University of Cambridge Madingley Road, Cambridge, CB2 0EZ United Kingdom
AU: Fielding, E J
EM: eric.fielding@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, 91109 United States
AB: The city of Bam in eastern Iran was struck by a deadly Mw 6.6 earthquake on 26th December 2003. This event was one of the first earthquakes for which Envisat ASAR data were available. Using interferograms and azimuth offsets from ascending and descending tracks, we construct a 3D displacement field of the deformation due to the earthquake. Elastic dislocation modelling shows that this observed deformation pattern cannot be explained by models involving slip on a single planar fault, which significantly underestimate eastward and upward motions SE of Bam. We find that the deformation pattern observed can be best explained by slip on two subparallel faults. Approximately 85% of moment release from the earthquake occurred on a previously unknown strike-slip fault running into the centre of Bam, with peak slip of 2.7 m occurring at a depth of 5 km. The location of this fault is consistent with the largest observed surface ruptures. The remainder of the deformation occurred as a combination of strike-slip and thrusting motion on a parallel fault -- a southward extension of the previously-mapped Bam Fault approximately 5 km to the east of the main fault. The geometry and proximity of the two faults suggest that they must interact at depth; similarly complex geometries of faulting have been inferred for recent earthquakes in the Gowk fault zone around 100 km to the NW.
DE: 7230 Seismicity and seismotectonics
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting