A new inversion method of Coda waveforms to determine spatial distribution of Coda scatterers in the crust and uppermost mantle

Abstract

We have developed a new inversion method of coda waveforms from local earthquakes to estimate the inhomogeneous spatial distribution of scattering coefficient in the crust and the uppermost mantle. A preliminary analysis by this method was applied to the data observed at the Hokuriku district, central Japan. Inhomogeneous structures have been revealed in both horizontal and vertical directions as follows: (1) Strong scatterers are distributed in some localized parts of the surface layer and the upper crust; (2) Some of the strong scatterers seem to be related to major active faults; (3) Horizontal variation of scattering coefficient is smaller in the uppermost mantle than in the crust. We have found that the method presented here is effective enough to investigate deterministically the inhomogeneity in the shallow part of the crust.