Seismic velocity structure of Unzen Volcano, Japan, and relationship to the magma ascent route during eruptions in 1990-1995.

Subsurface structures may control the migration of magma beneath a volcano. We used high-resolution seismic tomography to image a low- P-wave velocity (Vp) zone beneath Unzen Volcano, Japan, at depths of 3-16 km beneath sea level. The top of this low-Vp zone is located beneath Mt.