HR: 0800h
AN: G51B-0083    [Abstracts]
TI: Subsidence induced by ground-water withdrawels across the Wasatch Front, Salt Lake Valley, Utah
AU: * Bawden, G W
EM: gbawden@usgs.gov
AF: US Geological Survey, 3020 State University Drive East Modoc Hall Suite 4004, Sacramento, CA 95819 United States
AU: Stolp, B J
EM: bjstolp@usgs.gov
AF: US Geological Survey, 2329 W Orton Circle, West Valley City, UT 84119 United States
AU: Chang, W
EM: wchang@mines.utah.edu
AF: University of Utah - Department of Geology and Geophysics, 135 South 1460 East, Salt Lake City, UT 84112 United States
AU: Smith, R B
EM: rbsmith@mines.utah.edu
AF: University of Utah - Department of Geology and Geophysics, 135 South 1460 East, Salt Lake City, UT 84112 United States
AU: Brandt, J T
EM: jbrandt@usgs.gov
AF: US Geological Survey, 3020 State University Drive East Modoc Hall Suite 4004, Sacramento, CA 95819 United States
AB: Interferometric Synthetic Aperture Radar (InSAR) imagery of the Salt Lake Valley shows a northwest-trending, 12- x 17-km elongate subsidence bowl, centered on Salt Lake City, that has an annual subsidence rate of of 12 mm/year and seasonal uplift of ~30 mm. Radar imagery from the European Space Agency's ERS satellites (1992-2000) shows that the subsidence has been persistent over this period, with >100 mm of cumulative line-of-sight range change in the valley. On the basis of water-well records and radar imagery, the onset of the subsidence likely predates the 1992 launch of the ERS-1 satellite. The seasonal uplift has been observed in a few fall interferograms, is confined to the southern portion of the basin, and has a maximum magnitude of 30 mm. The western, southern, and eastern margins of the deforming bowl, as observed in the interferograms, are distinctly linear and presumably indicate impermeable or semi-permeable barriers to ground-water flow across faults in the Wasatch fault system. A preliminary evaluation of ground-water levels throughout the Salt Lake Valley region suggests a correlation between the seasonal and annual deformation and the location and timing of ground-water withdrawels. Subsidence of this magnitude will produce both seasonal and long-term human-induced horizontal strain gradients that will need to be taken into account when assessing seismic hazard associated with the low slip rates along the heavily populated Salt Lake segment of the Wasatch Front.
DE: 8110 Continental tectonics--general (0905)
DE: 7205 Continental crust (1242)
DE: 1829 Groundwater hydrology
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting