Fig. 4
From: Anelastic properties beneath the Niigata–Kobe Tectonic Zone, Japan
a Map showing Q −1p at depths of 5, 10, 25, and 40 km. The color scale is shown in the right bottom panel. Black triangles represent active volcanoes. Gray dots at a depth of 10 km represent earthquakes (M ≥ 1) in a depth range of 5–15 km in 2003–2015, and stars at depths of 10 and 25 km denote earthquakes (M ≥ 6.5) at depths of ≤20 km from 1923 to 2015. Deep low-frequency earthquakes that occur within 2.5 km of each depth slice are indicated by white circles. The black dashed line shows the 40 km iso-depth contour of the upper surface of the Philippine Sea slab (Hirose et al. 2008; Nakajima et al. 2009). Areas with recovery rates of <20% for the two-grid-model of checkerboard resolution test are shaded in gray. b Vertical cross section of Q −1p along line A–B shown in the right bottom panel in a. Dashed lines indicate the Moho (Zhao et al. 1992b) and the upper surface of the Philippine Sea slab. The intersection of line A–B with the ISTL is indicated by a green arrow. Black triangles at the top denote active volcanoes. Gray dots and white circles represent earthquakes (M ≥ 1) and low-frequency earthquakes, respectively, that occurred within 5 km of line A–B. c Vertical cross section of P-wave velocity perturbations along line A–B (Nakajima and Hasegawa 2007). Other symbols are the same as in b