Fig. 2

Relative reflection strengths of an inclined stratification structure along NS vertical cross section. Reflection strengths take account of inclined angles (0°, 5°, 10°, 15°, and 20°). The color scale and plane locations are shown on the middle left. Blue stars represent hypocenters of deep low-frequency earthquakes (DLFs). Hypocenters occurring within 5 km of each plane are plotted. Black lines represent active faults. The assumed angle of inclination is shown at the upper left-hand side in each panel. Blue lines indicate area in which the number of data points assigned to each grid cell exceeds the threshold value of 10,000. We consider that relative reflection strengths within the blue lines are sufficiently accurate