Fig. 9

Locations of the sources of the volcanic tremors. a Epicentral distribution, b depth section along E–W section, and c depth section along A–B section. Red stars indicate the locations of the sources of the tremors, obtained using the envelope correlation method. Orange circles show the hypocenters of VT earthquakes that occurred from 07:32 to 17:00 on June 29, 2015. Blue circles indicate the hypocenters of low-frequency earthquakes. Black circles and gray quadrilaterals represent the locations of vents and the open-crack sources, respectively