Shear-wave splitting analysis of the upper mantle at the Niigata-Kobe Tectonic Zone with the data of the Joint Seismic Observations at NKTZ

摘要: We conducted seismic observations with a spatially high density network at the Niigata-Kobe Tectonic Zone, central Japan. The was used for analysis of shear-wave splitting. Large lateral variations were found in polarization direction data: northern part research area yields directions NW-SE (Region A), NNE-SSW B), eastern NE-SW C), and southern E-W D). Regions B C could be explained by preferred orientation olivine caused flow subducting Philippine Sea plate. However, cause anisotropic region which related to heterogeneous structure also plausible. Region A might both Pacific slabs. D not produced wedge an beneath slab. variation does support model that NKTZ is collision region.