Significant underwater gas emissions at Nishinoshima volcano, Japan

Satellites are registering significant underwater gas emissions at Nishinoshima volcano, Japan following increased eruptive activity at the volcano that started in September 2022. The activity at the volcano further intensified on October 2 and 3.

Tokyo VAAC reported first venting on October 1, with ash rising up to 1.8 km (6 000 feet) above sea level at 01:40 UTC, drifting E. However, satellites were observing an increase in activity since September 23.¹

From October 5 to 12, ash plumes were rising 2.2 – 3.5 km (7 200 – 11 500 feet) a.s.l., drifting in multiple directions.

Ash emissions with varying intensity continued through October and into November, accompanied by significant underwater gas emissions.

Geological summary

The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74.

Another eruption that began offshore in 2013 completely covered the previously exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since.

The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m (702 feet) of the sea surface 9 km (5.6 miles) SSE.²

References:

¹ Increased ash emissions at Nishinoshima volcano, Japan – The Watchers – October 3, 2022

² Nishinoshima – Geological summary -GVP

Featured image: Nishinoshima volcano on November 5, 2022. Credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers