HR: 1340h
AN: S53B-1271    [Abstracts]
TI: Reanalysis of the stationary phase method in ambient noise study
AU: Zhan, Z
EM: zwzhan@mail.ustc.edu.cn
AF: National Geophysical Observatory at Mengcheng, School of Earth and Space Science, USTC, 96 Jinzhai Road, Hefei, Anh 230026, China
AU: * Ni, S
EM: sdni@ustc.edu.cn
AF: National Geophysical Observatory at Mengcheng, School of Earth and Space Science, USTC, 96 Jinzhai Road, Hefei, Anh 230026, China
AB: Extracting Green's function between stations from the cross correlation has been proven to be an effective method theoretically and experimentally. It has been widely applied in surface wave tomography of the crust and upmost mantle. However, there are still a lot of controversies about why this method works. Assuming the stationary phase approximation, Snieder (2004) evaluated the contribution of scatterers distributed in whole space to cross-station correlation function, and he proposed that it is the constructive interference of waves emitted by the scatterers near the receiver line leads to the Green's function. Instead, we evaluate the cross correlation between station pairs numerical for a diffuse wave field, and our numerical computation indicates that cross correlation differs from Greens¡¯ function substantially in both amplitude and phase when frequency is low, where stationary phase approximation fails to work. We also demonstrate that this inaccuracy of stationary phase approximation can be ignored when the station distance is larger than several wavelengths.
DE: 7205 Continental crust (1219)
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory
SC: Seismology [S]
MN: 2007 Fall Meeting