Abstract
Coda-Q reflects subsurface heterogeneity. In the past, from the variation of Q value against time or space, stochastic information on surface medium that seismic waves travel through has been obtained. For example, it was said that Q value shows abnormal value around volcanoes or before earthquakes. However Q value does not indicate any deterministic information on location of scatterers, source, boundary of layers and so on. Coda-Q is influenced by various parameters in the underground because the coda-wave is formed by the summation of scattered waves, so it is difficult to determine factors that influence coda-Q. In this study, we attempt to obtain non-stochastic parameters of the subsurface medium from stochastic parameter Q. We employ a 2-D finite difference method and simulate seismic scattering of a 2D model to see if we can obtain the information on the stress loaded to the model (i.e. the magnitude and the direction of the stress). Our analysis of the coda-wave reveals the proportional relation between the loaded stress and the coda-Q. In addition, the variation of the coda-Q is dependent on the direction of the stress. As a conclusion, we suggest the possibility that we can get the order and the direction of the loading stress if we obtain the time-variant change of coda-Q. It means that we could obtain non-stochastic parameters from the coda-wave that is used as a stochastic measure of the medium.
