Fig.13

(a) Vertical cross-sections of V _p images in the direction of PHS plate subduction (Y1–Y1′,Y27#x2013;Y2′,Y3–Y3′) and PHS plate strike (X–X′). (b) Vertical cross-sections for the RRT results. Thick lines and thin lines indicate contour lines of V _p . Position of the cross-sections is shown in the insert map. Masking obscures areas of low reliability (see Fig. 6 and the text for details). The red triangle and gray rectangle above each panel mark the position of active volcanoes and the Kyushu Mountains, respectively. Circles indicate the epicenters of the relocated events. Earthquake hypocenters (circles) within 15 km of each cross-section are plotted.