HR: 0830h
AN: G31B-0710    [PDF]
TI: Anomalous Crustal Deformation in the Central Nevada Seismic Belt Detected by InSAR.
AU: * Gourmelen, N
EM: ngourmelen@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Sciences, 4600 Rickenbaker Causeway, Miami, FL 33149 United States
AU: Amelung, F
EM: amelung@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Sciences, 4600 Rickenbaker Causeway, Miami, FL 33149 United States
AB: The Central Nevada Seimic Belt (CNSB) is one of the tectonically most active areas in North America. The CNSB was the location of major normal and strike-slip earthquakes in 1915 (Pleasant Valley M7.5) and in 1953 (four Magnitude 6.8-7.2 during 6 month). GPS measurements have shown ongoing crustal deformation at rates of 5 to 10 mm/yr across the CNSB. Those geodetic estimates of deformation are by a factor of 3-4 higher than geologic fault slip rates derived by paleoseismology. A possible explanation for this discrepancy between geodetic and geologic rates of deformation is that the geodetic measurements do not reflect long-term strain accumulation but transients such as post-seismic relaxation following the 1915-1954 earthquakes. We measure crustal deformation in the CNSB using Interferometric Synthetic Aperture Radar (InSAR). We obtained 9 independent interferograms each covering four adjacent frames (~400 km in along-track direction) spanning 4-7 years using ERS SAR imagery acquired between 1992 and 2001. A precise displacement map obtained by stacking (averaging) the interferograms shows shortening of the distance between the ground and the satellite at a rate of ~2mm/yr (range change). The maximum range change occurs in the epicentral area of the 1954 Dixie Valley and 1915 Pleasant Valley earthquakes. This suggest that we may see post-seismic deformation caused by these normal events. We discuss models of post-seismic deformation to explain the observed deformation.
DE: 1208 Crustal movements--intraplate (8110)
DE: 1640 Remote sensing
DE: 1709 Geodesy
DE: 7209 Earthquake dynamics and mechanics
DE: 8109 Continental tectonics--extensional (0905)
SC: Geodesy [G]
MN: 2003 Fall Meeting