Beyond Single Interferograms: Inference of Subsurface Processes with Subtle Deformation Signatures from Time Series InSAR

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Beyond single interferograms: inference of subsurface processes with subtle deformation signatures from time series InSARHoward A. Zebker, Paul SegallStanford UniversityInSAR, an exceptional technique for visualizing andquantifying crustal deformation patterns, has largely beenlimited in application to arid environments. Subtlephenomena such as interseismic strain accumulation orpre-eruptive deformation of volcanic edifices can producesurface signatures that are undetected in single radarinterferograms because of i) temporal decorrelation noisedue to vegetation and ii) propagation through aspatially-variable troposphere. We propose to view thesesmall signals using data acquired by Envisat, a newsatellite launched by ESA in March 2002. This new radarincorporates electronic beam steering, which permitsmultiple observations of a given study site during asingle orbit cycle. Furthermore, rapid beam switchingenables a ScanSAR capability for imaging wide swaths.Although the satellite is to be orbited in a 35 dayrepeat orbit similar to that of ERS-1 and ?2, ScanSAR canyield much denser temporal data, with each point on theground imaged four times during each cycle. We proposehere to develop algorithms and methods to produce routineScanSAR interferograms resulting in dense deformation timeseries measurements. We also will develop filters basedon spatio-temporal models of expected signals and errorsources to coax deformations from within the noisybackground.