C 3 function: the Correlation of Coda of Correlation Function
Speaker: Kai-Xun Chen Adviser: Po-Fei Chen
Abstract Date: 2014/10/09
Correlations of ambient seismic noise are now widely used to retrieve the Earth response between two points. However, usually the distribution of the noise sources does not provide a perfect random noise field. In this case, the theoretical requirements are not completely fulfilled, and the noise correlation does not perfectly reconstruct the surface-wave Green’s function, as some fluctuations remain in the correlation results. To resolve this problem, Stehly [2008] reconstruct the surface-wave Green’s function by iterating the correlation process over the tail of the noise-based correlation function. The later part of the C1 is meaningful and contains multiply scattered waves with properties of regular earthquake codas. It has been demonstrated that the so-called C3 function shows the surface-wave part of the Green’s function. Froment [2011] presented the results of the next iterative step (i.e. C5), which show that some coherent signal is still present in the coda of the C3 function. Ma [2012] demonstrated that all of the station-to-station Green’s functions can be obtained whether or not they operate at the same time. That is, Green’s functions between stations operating at different times, can be constructed.
Reference
Stehly, L., M. Campillo, B. Froment, and R. L. Weaver (2008), Reconstructing Green's function by correlation of the coda of the correlation (C3) of ambient seismic noise, J. Geophys. Res., 113, B11306, doi:10.1029/2008JB005693.
Froment, B., M. Campillo, P. Roux (2011), Reconstructing the Green’s function through iteration of correlations. C. R. Geosci. 343:623–32
Ma, S., and G. C. Beroza (2012), Ambient-field Green's functions from asynchronyous seismic observations, Geophys. Res. Lett., 39, 06301,doi:10.1029/2011GL050755.
Campillo, M., and A. Paul (2003), Long-range correlations in the diffuse seismic coda, Science, 299, 547–549, doi:10.1126/science.1078551.