HR: 09:00h
AN: S21D-04    [Abstracts]
TI: Extracting seismic time domain Green's functions from ambient noise
AU: * Sabra, K G
EM: ksabra@mpl.ucsd.edu
AF: Marine Physical Laboratory Scripps Inst. Ocean. UCSD, 9500 Gilman Drive, La Jolla, CA 92093-0238 United States
AU: Gerstoft, P
EM: gerstoft@mpl.ucsd.edu
AF: Marine Physical Laboratory Scripps Inst. Ocean. UCSD, 9500 Gilman Drive, La Jolla, CA 92093-0238 United States
AU: Roux, P
EM: philippe@mpl.ucsd.edu
AF: Marine Physical Laboratory Scripps Inst. Ocean. UCSD, 9500 Gilman Drive, La Jolla, CA 92093-0238 United States
AU: Kuperman, W A
EM: wak@mpl.ucsd.edu
AF: Marine Physical Laboratory Scripps Inst. Ocean. UCSD, 9500 Gilman Drive, La Jolla, CA 92093-0238 United States
AU: Fehler, M C
EM: fehler@lanl.gov
AF: Los Alamos National Laboratory, P. O. Box 1663, MS D443 Bldg 1572 Room 108, Los Alamos, NM 87545 United States
AB: It has been demonstrated experimentally that an estimate of the Green's tensor between two seismic stations can be obtained from the long-time average of the cross-correlation of ambient noise at the two stations [Shapiro and Campillo, Geophys. Res. Lett., 31, 2004]. This result provides a means to find trace data that can be used to infer Earth structure without the use of active seismic sources or earthquakes. The availability of numerous broadband seismic recording stations throughout the world makes this technique attractive for simulating virtual large dense seismic arrays for continuous sampling of the earth's crust. Cross-correlations have been computed from ambient noise recorded over 150 broadband seismic stations located in California. A simple and straightforward processing yielded hundreds of cross-correlation pairs, for receiver separations of up to 250 km, that clearly exhibit coherent broadband dispersive wavetrains. A record section of the waveforms as a function of increasing receiver separation shows clearly that the recovered signals are propagating wavetrains. The potential use of this passive seismic imaging technique was investigated across 1) the frequency band [5mhz-10Hz], 2) the spatial distribution of the pair of stations (in range and azimuth), 3) averaging time periods of 1 day to 1 month.
DE: 9350 North America
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory and modeling
DE: 7294 Instruments and techniques
DE: 7203 Body wave propagation
SC: Seismology [S]
MN: 2004 AGU Fall Meeting