HR: 0800h
AN: G51C-0626    [Abstracts]
TI: Investigating the Creeping Segment of the San Andreas fault using a Maximum Likelihood Persistent Scatterer Technique
AU: Agram, P S
EM: shanker@stanford.edu
AF: Radar Interferometry Group, 350 Serra Mall, Packard 302, Stanford, CA 94305, United States
AU: * Ryder, I
EM: isabelle@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall, UC Berkeley, Berkeley, CA 94720, United States
AB: Numerous new methods that use multiple SAR interferograms have been developed recently to study the temporal characteristics of deformation in a region of interest. Persistent scatterers (PS) approach relies on identifying a network of pixels in the interferogram whose scattering properties vary little with time. Various PS- InSAR methods have been proposed and have been shown to work reliably in urban environments. The Stanford Method for PS (StaMPS) was the first method developed to extend the scope of PS-InSAR, to work effectively in vegetated regions. The maximum likelihood approach to PS selection (also developed at Stanford) is a new method that has been shown to be effective in identifying PS in the vegetated areas in the Bay Area in California, USA. The primary advantage of both these methods are that they do not assume a model for the deformation pattern. Ability of the maximum likelihood method to identify a reasonably dense PS network in vegetated regions, where conventional InSAR and other PS-InSAR algorithms failed, makes it a powerful tool for estimating the deformation time-series in heavily decorrelated regions. This method identifies PS by estimating the most likely Signal-to-Clutter Ratio (SCR) by comparing the time-series of interferometric phase of pixels in a stack of interferograms with a statistical model describing the interferometric phase. We will present the results from maximum likelihood PS-InSAR analysis of the creeping section of the San Andreas fault in central California, one of the first areas to which this new technique has been applied. This section of the fault is known to creep at rates in excess of 20 mm per year. Geodetic measurements up to now ( e.g. from creepmeters, GPS) have tended to have poor spatial and/or temporal resolution. A stack of multiple ERS interferograms covering the creeping segment between 1992 and 2001 gives good spatial information about surface deformation, but the stacking technique assumes linear displacement gradients over time. The PS approach offers the opportunity to generate time series of surface displacement at a potentially large number of points, which may provide important clues about the mechanics of creep at depth.
DE: 0933 Remote sensing
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1209 Tectonic deformation (6924)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
SC: Geodesy [G]
MN: 2007 Fall Meeting