High-level eruption at Fukutoku-Oka-no-Ba submarine volcano, ash to 16.4 km (54 000 feet) a.s.l., Japan


A major eruption started at the Japanese submarine Fukutoku-Oka-no-Ba volcano at around 21:20 UTC on August 12, 2021, and continued into August 13.

According to the Tokyo VAAC, volcanic ash was rising up to 16.4 km (54 000 feet) above sea level at 23:50 UTC and heading SSW toward the Philippines.1

Their latest VA Advisory, issued at 06:00 UTC, confirmed ash was still rising from the volcano at 05:20 UTC.

Eruption at Fukutoku-Oka-no-Ba submarine volcano. Image credit: JMA/Himawari-8, NII/NICT, TW. Acquired at 05:20 UTC on August 13, 2021

Eruption at Fukutoku-Oka-no-Ba submarine volcano. Image credit: NASA/NOAA SuomiNPP/VIIRS, TW. Acquired on August 13, 2021

The last eruptive episode at this volcano started on February 3, 2010, and lasted to ~April 8, 2010 (VEI 1).

Numerous eruptions were recorded in 20th century, two of them VEI 3 and three VEI 2.


The Japan Coast Guard has stated that "the eruption was so large that it could not be observed in close proximity," and is calling for caution on vessels navigating and flying aircraft in the vicinity.3

An observation conducted by the Japan Coast Guard in June confirmed that volcanic activity had become more active, such as discoloration of the surrounding sea surface.

Geological summary

Fukutoku-Oka-no-ba is a submarine volcano located 5 km (3.1 miles) NE of the pyramidal island of Minami-Ioto. Water discoloration is frequently observed from the volcano, and several ephemeral islands have formed in the 20th century.

The first of these formed Shin-Ioto ("New Sulfur Island") in 1904, and the most recent island was formed in 1986.

The volcano is part of an elongated edifice with two major topographic highs trending NNW-SSE, and is a trachyandesitic volcano geochemically similar to Ioto.2


1 Tokyo VAAC – VA ADVISORY DTG: 20210813/0600Z – FUKUTOKU-OKA-NO-BA 284130

2 Fukutoku-Oka-no-Ba – Geological summary – GVP

3 Eruption at Fukutoku-Okanoba, a submarine volcano near Iwo Jima, for the first time in 11 years – NHK

Featured image: Eruption at Fukutoku-Oka-no-Ba submarine volcano. Image credit: JMA/Himawari-8, NII/NICT, TW. Acquired at 05:20 UTC on August 13, 2021

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One Comment

  1. A reasonable geologic assessment says there are about 100.000 active volcanoes pouring emissions into the sea from where a lot goes into the atmosphere possibly affecting climate. But nobody to my knowledge has tried to check the faults and tectonic plates to count volcanoes and vents. Interesting?

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