Variation in aseismic slip along the creeping section of the San Andreas fault from space-based geodetic data

Frederique Rolandone(1) , Ingrid Johanson(2) , Eric Fielding(3) , and Roland Burgmann(2)

(1) Universite Pierre et Marie Curie, 4 Place Jussieu, 75252 PARIS, France
(2) UC Berkeley, 215 McCone Hall, 94709 Berkeley, United States
(3) Jet Propulsion Laboratory, 4800 Oak Grove Drive, 91109 Pasadena, United States


In central California most of the relative motion between the Pacific and North American plates is accommodated by strike slip along the San Andreas fault system. Along the central San Andreas fault (CSAF), from San Juan Bautista to Parkfield, almost all the slip along the CSAF in the brittle upper crust is accommodated aseismically. We use GPS, InSAR and trilateration data to resolve both the distribution of aseismic slip along the CSAF, and the deformation across adjacent, secondary fault structures. Since 2003, we conducted several GPS surveys along the CSAF. The dense GPS measurements, along with data from permanent GPS stations in the area, allow us to constrain the regional strain distribution and contributions from adjacent faults. We combine GPS and InSAR data to better resolve active strain accumulation and aseismic slip along the CSAF. We use data from the ENVISAT and RADARSAT satellites. To overcome the limited coherence between SAR images and to enhance the crustal signal relative to atmospheric and orbital effects, we combine multiple interferograms. InSAR is well suited to monitoring details of the shallow slip along the CSAF and, in concert with the broadly spaced GPS velocities, to resolving the distribution of deformation along and across the plate boundary. The results are the basis for determining the kinematics of spatially variable fault slip on the CSAF, and help to better constrain the fault's constitutive properties, and fault interaction processes.


Workshop poster


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