Configuration of subducting Philippine Sea plate beneath southwest Japan revealed from receiver function analysis based on the multivariate autoregressive model

摘要: [1] We construct a detailed image of velocity discontinuity beneath southwest Japan by using receiver functions. We first propose an improved function estimation method based on the statistical multivariate autoregressive model. Then we apply new to teleseismic waveform data recorded high-density seismograph network in Japan. The results show clear at 30 km depth southern Shikoku region. This discontinuity, corresponding boundary between oceanic crust and high-velocity layer (the Moho) Philippine Sea plate (PHS), continues down north indicating that aseismic PHS extends central Chugoku continental Moho is also clearly imaged contour shows rather complicated feature with ridges valleys. most significant ridge located around longitude 133°E, west which contours are basically directed north-south, changing west-east east. Beneath western part this ridge, hypocenters microearthquakes above while earthquakes mainly occur below within mantle, eastern ridge.