[SCG66-P10] Reflection seismic survey data around ring structures of the submarine Kikai Caldera, south offshore Kyushu, Japan
Keywords:Reflection seismic data, Kikai caldera
North of the northern ring structure, a bathymetric bulge is recognized and shows a gentle convex shape on reflection seismic profiles. It is likely to represent the tumescence of the Kikai activities. Beneath the bathymetric bulge, a relatively flat and eastward dipping surface is clearly shown. The formation of this surface is likely to provide us a key to evaluate the of most recent activities of the Kikai Caldera. South of the south ring structure, a funnel-shaped feature is recognized in our reflection seismic data. Based on field perception from Miyakejima Volcano, we interpreted it as a volcanic crater associated structure, probably indicating a phreatomagmatic explosion controlled by the lateral evolution of a feeder dike.