Fukutoku-Oka-no-Ba submarine volcano information top

Release date: October 27, 2021 (JST)

Discovery and observation of the Fukutoku-Oka-no-Ba pumice raft at sea

　On October 14, 2021, a pumice raft was encountered in the sea northwest of Amami-Oshima Island by AIST researchers during a research voyage by S/V Shinsei-maru. The observed raft was elongated from east-northeast to west-southwest, and the width of the pumice-rich area was about 7-8 m-wide. The size of pumice clasts ranged from approximately 5 cm to 0.1 cm.

View of the pumice raft seen from a distance.The direction of the elongated raft extends from east-northeast to west-southwest．

Photo 1　View of the pumice raft seen from a distance. The direction of the elongated raft extends from east-northeast to west-southwest.

A closer view of the pumice raft. The width of the part where pumice clasts are concentrated is approximately 7-8 m.

Photo 2　A closer view of the pumice raft. The width of the part where pumice clasts are concentrated is approximately 7-8 m.

The ship was maneuvered to allow detailed observation of the pumice raft. This view from the side of the ship shows that the raft consists of relatively large pumice clasts with lengths of several centimeters, as well as fine (millimeter-sized) pumice pieces.

Photo 3　The ship was maneuvered to allow detailed observation of the pumice raft. This view from the side of the ship shows that the raft consists of relatively large pumice clasts with lengths of several centimeters, as well as fine (millimeter-sized) pumice pieces.

Pumice clasts pulled up onboard by a net. Some of them are rounded, but others maintain their original surface morphology from the time of eruption.

Photo 4　Pumice clasts pulled up onboard by a net. Some of them are rounded, but others maintain their original surface morphology from the time of eruption.

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IEVG (Research Institute of Earthquake and Volcano Geology）