HR: 0800h
AN: G51C-0847    [Abstracts]
TI: Measuring the slip rate on faults with InSAR in difficult interferometric conditions: The Denali Fault (Alaska).
AU: * Biggs, J
EM: julietb@earth.ox.ac.uk
AF: COMET, University of Oxford, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Wright, T
EM: timw@earth.ox.ac.uk
AF: COMET, University of Oxford, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AU: Lu, Z
EM: lu@usgs.gov
AF: USGS EROS Data Center, 47914 252nd Street, Sioux Falls, SD 57198 United States
AU: Parsons, B
EM: barry@earth.ox.ac.uk
AF: COMET, University of Oxford, Department of Earth Sciences, Parks Road, Oxford, OX1 3PR United Kingdom
AB: The Denali Fault, Alaska is a major strike-slip fault which ruptured in the M_w 7.9, 3 November 2002, Denali Earthquake - the largest strike slip earthquake in North America for more than 150 years. Geological estimates of Holocene offsets on the McKinley and Totschunda Faults suggests that the slip rate on the Denali Fault is 10-20mm/yr (Plafker, 1977) whereas geodetic estimates of the rate from VLBI (Ma et al, 1990), triangulation networks (Savage and Lisowski, 1991; Page and Lahr, 1971) and GPS (Fletcher, 2002) are around 5 mm/yr. Previous studies have measured interseismic deformation on several faults and folds, including the North Anatolian Fault (Turkey), the Karakorum Fault (Tibet) , the San Andreas Fault (California), and the Tainan Tableland (Taiwan). However, these studies all focus on fast moving features in flat, desert or urban areas. The Denali Fault is a more difficult target because the coherence is poorer and the deformation rate slower. Mountains, vegetation and snow-cover limit the time-span of individual interferograms to 1-2 years and mean that only a very small number of pixels are coherent in all the interferograms. A right-lateral slip rate of 5 mm/yr on the Denali Fault corresponds to a line of sight range change of about 2 mm/yr. Atmospheric errors in a single interferogram are typically of the order of 1 cm in the satellite line of sight so to detect this rate of strain acccumulation requires a large number of interferograms. Using synthetic data, we investigate and compare methods for detecting interseismic strain accumulation in these conditions including simple stacking, weighted stacking and time series approaches. We pay particular attention to data selection and error propagation. We use the large archive of SAR acquisitions collected during the period 1992-2002 by ESA satellites ERS-1 and ERS-2 and apply these methods to over 100 interferograms constructed from 4 tracks (2 ascending and 2 descending) centered on the Delta River Valley where the Trans-Alaska Pipeline crosses the Denali Mountains.
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 1243 Space geodetic surveys
DE: 8111 Continental tectonics: strike-slip and transform
SC: Geodesy [G]
MN: Fall Meeting 2005