Massive amounts of pumice stones washing ashore in Okinawa, may affect nuclear power plants, Japan

Massive amounts of pumice stones washing ashore in Okinawa, may affect nuclear power plants, Japan

A large number of pumice stones produced by massive undersea volcano eruption have washed ashore on the main island of Okinawa Prefecture and other places this week, affecting fisheries industry and ship operations. The pumice is also being reported in the Amami region of Kagoshima Prefecture. On October 27, a member of the Nuclear Regulation Authority urged officials to prepare as the pumice may affect the intake of water used for cooling nuclear reactors.

The source of the pumice is an underwater volcano eruption at Fukutoku-Okano-Ba in the Ogasawara island chain in August 2021, one of the largest among all land and sea eruption in Japan since 1945. The estimated volume of ejected pumice and ash was at least 100 million cubic meters.

According to the prefectural government, pumice stones have begun washing ashore on Kita-Daitojhima island in early October and have been confirmed throughout Okinawa Island as well.1

The government said about 10 tons of pumice have been removed every day at the fishing port of Hentona in the village of Kunigami, but the stones are said to have continued washing ashore at the port seemingly endlessly.

It said about 750 fishing boats have been unable to leave the port due to concerns about engine trouble.

According to an estimate by Toru Miyama, a senior researcher in ocean physics at the Japan Agency for Marine-Earth Science and Technology, pumice stones ejected from the volcano were swept away mainly by the westward Kuroshio countercurrent and washed ashore in Okinawa Prefecture.

Some of the stones then may be carried northward by the Kuroshio current and approach the Pacific side of the Shikoku region in early November and may approach Shizuoka and Chiba prefectures by late November.

At a regular meeting on October 27, Ishiwatari Akira, a member of the Nuclear Regulation Authority, said the pumice may affect the intake of water used for cooling nuclear reactors.2

Ishiwatari called officials to prepare as the stones will likely come to Japan's main island of Honshu.

Officials of the Nuclear Regulation Authority said one of the effective ways to get rid of pumice is the measure being taken at each plant to remove jellyfish in the event of a plague. They also say installing fences in front of the water intake equipment can work.

The source of pumice

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 13.3

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.

Image credit: Japan Coast Guard. Acquired August 13, 2021

The eruption ejected a huge amount of volcanic ash and pumice, and created a new volcanic island.4

Image credit: Japan Coast Guard. Acquired August 26, 2021

Image credit: Japan Coast Guard. Acquired August 26, 2021

Image credit: Japan Coast Guard. Acquired October 12, 2021

Pumice created during an eruption at Fukutoku-Oka-no-ba. Image credit: Japan Coast Guard. Acquired August 16, 2021

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.5

References:

1 Okinawa port clogged with pumice stones - The Japan News

2 Pumice may affect nuclear power plants in Japan - NHK

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

4 New island discovered after major submarine eruption at Fukutoku-Oka-no-Ba, Japan - The Watchers

5 Fukutoku-Oka-no-Ba - Geological summary - GVP

Featured image: Pumice near Okinawa, Japan on October 26, 2021. Credit: Copernicus EU/Sentinel-2, TW


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Comments

Mel 1 month ago

Pumice is a very light material rich in minerals. It can be used to nurture plants and soil. It can help to the skin and also to clean diverse surfaces. Instead of a problem, it can be taken as a good chance.

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