HR: 1340h
AN: G13A-0907    [Abstracts]
TI: GRACE gravity observations associated with two great earthquakes in 2004
AU: * Han, S
EM: schan@puuoo.gsfc.nasa.gov
AF: Planetary Geodynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States
AU: * Han, S
EM: schan@puuoo.gsfc.nasa.gov
AF: Goddard Earth Science and Technology Center, University of Maryland Baltimore County, Baltimore, MD 21228, United States
AU: Sauber, J
EM: jeanne@steller.gsfc.nasa.gov
AF: Planetary Geodynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States
AU: Ji, C
EM: ji@geol.ucsb.edu
AF: Department of Earth Sciences, University of California at Santa Barbara, Santa Barbara, CA 93106, United States
AU: McAdoo, D
EM: Dave.McAdoo@noaa.gov
AF: NOAA Laboratory for Satellite Altimetry, 1335 East-West Highway, Silver Spring, MD 20910, United States
AB: We report GRACE satellite observations of coseismic change and postseismic transients from two great earthquakes, the Sumatra-Andaman Island (thrust event; M 9.1) and North of Macquarie Island (strike-slip event; M 8.1) in December 2004. Instead of using global spherical harmonic solutions of monthly gravity fields, we estimated the regional gravity changes directly using over-flight satellite tracking data with regionally-concentrated basis functions (spherical Slepian basis) every 15-day interval. We found significant step-like (coseismic) and exponential-like (postseismic) behavior in a 3 year long time-series of the estimated coefficients for the spherical Slepian functions. We analyzed the coseismic results on the basis of the seismically-derived slip models in spatial and spectral domains. Also we evaluated alternate post-seismic mechanisms (afterslip, poroelastic rebound, and viscoelastic relaxation) with a particular interest in dilatation (sum of normal strain) change.
DE: 1200 GEODESY AND GRAVITY
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1217 Time variable gravity (7223, 7230)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
SC: Geodesy [G]
MN: 2007 Fall Meeting