Fukutoku-Oka-no-Ba submarine volcano information top
Release date: January 4, 2022 (JST)
Pumice drifting below the sea surface
Between November 7 and 11, 2021, AIST researchers on board the Tokai University Research and Training Vessel Bosei Maru collected pumice clasts drifting below the sea surface off Koniya port, Setouchi Town of Amami-Oshima Island. No pumice raft was observed on the sea surface at that time.
Pumice clasts were recovered 1) by a plankton net deployed from the rear of the vessel between sea surface and 1m deep, 2) from a strainer fitted to the intake of seawater for research on the bottom of the ship.
This observation indicates that pumice clasts may be present below the sea surface without surface expressions as pumice rafts.
Photo 1 Sampling of pumice using a plankton net off Koniya port. No pumice clasts were observed on the sea surface.
Photo 2 Pumice clasts pulled up on board using a plankton net. Maximum grain size is about 1 cm.
Photo 3 Pumice clasts recovered from a strainer fitted to intake of seawater used for research. Maximum grain size is about 2 cm. Intake is as deep as 5 m below the sea surface. These pumice clasts were captured while the ship sailed from around Nakanoshima Island to Amami-Oshima Island.
IEVG（Research Institute of Earthquake and Volcano Geology）
IGG（Research Institute of Geology and Geoinformation）