First Comparisons of ALOS PALSAR Data for Central and Northern California with Data from Other Satellites

Isabelle Ryder(1) and Roland Burgmann(1)

(1) UC Berkeley, McCone Hall, Berkeley 94704 CA, United States


At UC Berkeley we have an ongoing programme of accumulating InSAR measurements of tectonic surface deformation in central and northern California. Over the last decade we have used ERS, Envisat, Radarsat and JERS SAR data to measure motion across the San Andreas fault and others faults in the San Andreas system. With L-band PALSAR measurements, which promise to allow coherent measurements where ERS C-band data fails, we will be able to improve our ability to monitor complex temporal and spatial deformation patterns. We show ALOS PALSAR interferograms across the San Andreas fault system for the area to the east and south of San Francisco Bay, right down to the south end of the creeping segment at Parkfield. For comparison, we also show some other InSAR results using data from different platforms. The relatively short time elapsed since the start of ALOS data collection, and the temporally uneven distribution of acquisitions, means that only short time span interferograms have been constructed at this point, making it challenging to measure interseismic deformation. Short wavelength features with magnitudes of up to a few centimeters of range change in the interferograms are likely due to tropospheric water vapour. Our preliminary results show a promising degree of coherence over highly vegetated areas. Although the time spans are very short, some of the perpendicular baselines are several times greater than typical baselines used in C-band InSAR, and yet there is a high degree of coherence in the agricultural San Joaquin Basin to the east of the fault system (where C-band fails completely). With repeat SAR scenes covering a longer period of time, we anticipate being able to measure tectonic signals across faults in the San Andreas system robustly in the near future.



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