Fig. 2
Seismicity rate changes that followed the Kumamoto earthquake sequence. Seismicity rate changes at depths of (a) 5 km, (b) 10 km, and (c) 15 km. The seismicity rate change is shown by the logarithm of the ratio of the number of events for the postseismic period (Ra) to that for the preseismic period (Rb). The stars denote the epicenter of the mainshock. The triangles denote active volcanoes. The black dashed lines show prefectural boundaries. The light green rectangles show the main rupture zone of the Kumamoto earthquake by Asano and Iwata (2016). The light green dashed lines show the study region (in Sects. 3–5), where seismicity rate changes are investigated in this study. Grey lines show active faults