HR: 11:50h
AN: G52A-07    [Abstracts]
TI: Measuring vertical deformation in the Seattle, WA urban corridor with satellite radar interferometry time series analysis
AU: * Finnegan, N J
EM: njf7@cornell.edu
AF: Department of Earth and Atmospheric Sciences, Cornell University, Snee Hall, Ithaca, NY 14853, United States
AU: Pritchard, M E
EM: mp337@cornell.edu
AF: Department of Earth and Atmospheric Sciences, Cornell University, Snee Hall, Ithaca, NY 14853, United States
AU: Lohman, R
EM: rbl62@cornell.edu
AF: Department of Earth and Atmospheric Sciences, Cornell University, Snee Hall, Ithaca, NY 14853, United States
AU: Lundgren, P R
EM: paul.lundgren@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AB: Satellite radar interferometry (InSAR) time series analysis (e.g., Lundgren et al., 2001) can reveal rich patterns of deformation in both time and space. As the technique is sensitive to mm-scale vertical deformation over large and spatially extensive regions, it provides a useful geodetic tool where satellite coverage and radar phase coherence permit. Here we apply InSAR time series techniques based on the Small BAseline Subset Algorithm (SBAS) (Berardino et al., 2002) using data from three satellites (ERS 1, ERS2, and RADARSAT) to the urban corridor between Tacoma, Seattle and Everett, WA, over the time period 1992 - 2007. The target of our work is to better characterize the nature of active faulting and deep-seated landsliding within the densely populated study area. Additionally, we seek to independently quantify how localized short-wavelength deformation is contaminating data collected from the ~ 12 GPS stations in the eastern Puget Sound region. Comparisons of InSAR time series inversions to data from 4 GPS stations temporally and spatially overlapping the available InSAR observations reveal that surface displacement computed from InSAR matches the GPS deformation within the range of error reported for vertical GPS data (~ 4mm). Contemporaneous surface velocity maps generated via linear regression to two independent time series inversions from overlapping ERS satellite tracks 428 and 156 show striking agreement in the pattern of surface velocity, and effectively resolve rates as low as 1 mm/yr. Based on the results of our velocity mapping, we provide new constraints on surface deformation in the Seattle metro region. First, between 1992 and 2007 we document subsidence (~ 1-3 mm/yr) over much of the region characterized by Holocene infilling of the Puget Sound by lahar and floodplain sedimentation. This deformation is consistent with subsidence due to sediment compaction and de-watering. Second, between 1992 and 2007 we document no slow landslide deformation on any of the numerous mapped slide complexes within Seattle. Regions of known active landsliding, such as along Perkins Lane in Seattle, exhibit radar phase de- correlation. These observations are therefore consistent with relatively infrequent and rapid landslide deformation within Seattle. Finally, we note a NW-SE striking, sharp linear gradient in deformation near Federal Way, WA. As this feature is located just north of the Tacoma Fault Zone, it may mark the location of a previously unmapped fault splay that is serving as a barrier to local groundwater flow.
DE: 1211 Non-tectonic deformation
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 1826 Geomorphology: hillslope (1625)
DE: 1872 Time series analysis (3270, 4277, 4475)
SC: Geodesy [G]
MN: 2007 Fall Meeting