Japan has gained a new island after an undersea volcanic eruption 1,200km south of Tokyo created a landmass about 100 metres across. The tiny island emerged near Iwoto island in the Ogasawara chain following a series of eruptions that began in October.
Fukashi Maeno, an associate professor at Tokyo University's earthquake research institute, confirmed that phreatomagmatic eruptions – explosive interactions between magma and water – occurred about a kilometre off Iwoto. Plumes of smoke and ash rose over 50 metres high every few minutes, with large rocks and pumice stones observed in the discoloured sea.
Iwoto, site of a brutal World War II battle and one of Japan's 111 active volcanoes, lies near another new island formed in 2021. The area has seen similar eruptions between July and December last year and in June this year.
Maeno noted that the new island could grow or change shape if eruptions continue, but might also disappear due to erosion, as happened with islands formed in 1904, 1914 and 1986. However, continued volcanic activity could produce lava flows that create a more durable surface.
Japan's archipelago recently grew to 14,125 islands thanks to digital mapping, though it occasionally loses islands, such as Esanbe Hanakita Kojima, which slipped beneath the waves unnoticed in 2018.
