Unzen volcano is located in the western part of Kyushu, Japan. We carried out a seismic re ection survey at Unzen volcano in order to elucidate the structure of the volcano. Although the survey was conducted in a volcanic area under dif cult conditions, such as arti cial noises and a complex structure, we were able to resolve the structure beneath the pro le using vibrator sources and a large number of stacking signals. The processed depth sections con rmed that Unzen volcano developed in a

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... en structure, as has been suggested in other geological studies. We imaged many subsurface normal faults shallower than 1 km. These faults, mostly covered with volcanic lava and deposits, were identi ed at the surface. Strong re ectors were found at a depth of approximately 3 km. They were located just above the pressure source of the latest eruption, as inferred from geodetic data. The geometric relationship between the re ection image, the pressure source location, and the lava dome suggests that the conduit from the lava dome could connect to the magma chamber located 4 km away from the lava dome.