HR: 0800h
AN: G51C-0840    [Abstracts]
TI: Kinematics, asperities and seismic potential of the Hayward fault, California from ERS and RADARSAT PS-InSAR
AU: * Funning, G J
EM: gareth@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, University of California 215 McCone Hall, Berkeley, CA 94720 United States
AU: Burgmann, R
EM: burgmann@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, University of California 215 McCone Hall, Berkeley, CA 94720 United States
AU: Ferretti, A
EM: alessandro.ferretti@treuropa.com
AF: Tele-Rilevamento Europa, Via Vittoria Colonna, 7, Milano, 20149 Italy
AU: Novali, F
EM: fabrizio.novali@treuropa.com
AF: Tele-Rilevamento Europa, Via Vittoria Colonna, 7, Milano, 20149 Italy
AU: Schmidt, D A
EM: das@uoregon.edu
AF: University of Oregon, Department of Geological Sciences 1272 University of Oregon, Eugene, OR 97403 United States
AB: The Hayward fault is currently considered to carry the greatest risk of a destructive (M_w ~ 7.0) earthquake of all of the strike-slip faults in the San Francisco Bay Area, California. Part of the San Andreas Fault Zone, it is estimated to accommodate some 25% of the total Pacific-N America relative plate motion at this latitude. Published studies using conventional InSAR, creepmeter and GPS data suggest that on average the upper 4--6 km of the fault is creeping at a rate of approximately 5 mm/yr, approximately half of published geologic slip-rate estimates. InSAR data have already been shown to provide considerable insight into the kinematic behaviour of the Hayward fault (Schmidt et al., 2005, JGR). Three areas have been identified where the local creep rate, estimated on the fault using boundary element elastic modelling, is very low (<2 mm/yr). Given their location at the base of the fault, these probably represent locked asperities, areas which could be the loci of deformation in any future earthquake. Current studies are limited by the poor interferometric coherence seen east of the fault; since only one side of the fault has adequate data coverage, resolution in models derived from such data is necessarily limited, especially at depths greather than 5 km. In this study we apply permanent scatterer InSAR (PS-InSAR) techniques to the full archive (1992--2004) of ERS and RADARSAT data covering the Hayward fault in both ascending and descending acquisition geometries. Thereby we create the most complete spatio-temporal picture of the deformation in this area yet assembled, with significantly improved data coverage on the eastern side of the fault. We use this dataset, combined with GPS and creepmeter data, to generate an improved model of the distribution of slip rate over the fault, utilising our time series to model in addition the evolution of this pattern over time. Results are compared with an expanded stack of conventional ERS interferograms covering the same time interval. We also use the improved spatial resolving power of the data to investigate different asperity models -- e.g. to determine the extent of each asperity, and to estimate its likely seismic potential. In future, such models may be useful in assessing and quantifying the state of friction on this and similar faults, allowing us to deepen our understanding of the behaviour of faults that are accumulating elastic strain.
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8111 Continental tectonics: strike-slip and transform
DE: 8163 Rheology and friction of fault zones (8034)
SC: Geodesy [G]
MN: Fall Meeting 2005