HR: 1330h
AN: G23A-01    [Abstracts]
TI: InSAR analysis of Subsiding Soils: Amherst and surroundings, NY
AU: * Becker, R
EM: richard.becker@wmich.edu
AF: Western Michigan University, Department of Geosciences, 1903 W. Michigan Ave, Kalamazoo, MI 49008-5241 United States
AU: Sultan, M
EM: mohamed.sultan@wmich.edu
AF: Western Michigan University, Department of Geosciences, 1903 W. Michigan Ave, Kalamazoo, MI 49008-5241 United States
AU: Giese, R
EM: glgclay@acsu.buffalo.edu
AF: University at Buffalo, Department of Geology, 876 NSC, Buffalo, NY 14260 United States
AU: Guay, B
EM: BradleyE.Guay@usace.army.mil
AF: US Army Corps of Engineers Buffalo District, 1776 Niagara Street, Buffalo, NY 14207 United States
AB: Amherst Town (140 km²), a northeast suburb Buffalo, New York, lies in the Erie-Ontario Lake Plain. Residential development in the north and central region is within or underlain by mostly glacial and lacustrine unconsolidated deposits of expansive silty-clay that is extremely soft in some areas. Foundation -related damages caused by horizonatal (lateral pressure) and vertical movement (subsidence) are estimated to affect more than 1000 homeowners. The subsidence is due, in part, to the shrink/swell nature of the clays (primarily illite with some chlorite) that respond to seasonal changes in soil moisture content. Neighborhood -scale subsidence, however, is potentially a concern if the underlying soft clays are dewatering and consolidating. The purpose of this analysis is to determine (1) if a regional subsidence patterns exists and (2) if subsidence corresponds to foundation damages and/or the soft soil regions. Radar interferometry will be used to provide the estimates of areal extent that are highly sought by the community. Interferograms were generated from 18 ERS-1 and ERS-2 scenes that were acquired over the 1992-2003 time period. Results from the 2 pass and 3 pass methods were unsatisfactory, primarily due to the inherent ambiguity related to difficulties in registration and inaccuracies of digital elevation (2 pass) and due to de-correlation over the long period (years) of deformation (3 pass). Our best results which we report here are from the 4 pass method for pairs of scenes that were selected (1992 through 1995) to encompass the wet-dry cycle (1991:wet; 1992-1995: dry). Good coherence was limited to interferograms generated from pairs of scenes that were acquired over short time periods and small spatial baselines (δT 1 day, B_perp < 50m), in periods of minimal vegetation (November scenes), and in subsets of images acquired with slightly longer temporal and spatial baselines (δT < 3months, B_perp < 200m) over developed areas. Inspection of the patterns displayed in the interferogram is here interpreted to indicate differential surface deformation in east central Amherst. The inferred deformation was found to coincide with locations where foundation damage was reported. We cannot entirely rule out a subtle residual topographic phase effect as a possible cause. Future plans involve further verification of these features using multi-temporal techniques to eliminate uncertainties related to topographic and atmospheric phase contributions.
DE: 1800 HYDROLOGY
DE: 6924 Interferometry
DE: 6969 Remote sensing
SC: Geodesy [G]
MN: 2005 Joint Assembly