New island forms following volcanic eruption in Japan.

A new island has formed off the coast of Iwoto (or Iōtō) Island (formerly known as Iwo Jima), about 1200 km to the south of Tokyo, following a series of eruptions on the Fukutoku Oka-no-Ba submarine volcano which began on 21 October 2023. Pumice rafts and volcanic plumes had previously been seen in the area, with the new island being detected by researchers from the University of Tokyo's Earthquake Research Institute on 30 October. 

Photo taken from a Kyodo News plane on 30 October 2023, shows a column of steam rising from the waters off Iwoto Island, previously known as Iwojima, in the Pacific Ocean. A new island of 100 metres in diameter, formed by masses of rock spewed from the plumes, is seen near the steam. Kyodo News Agency.

Eruptions in this area have led to the formation of new islands in the past, with the most recent forming in August 2021. Such islands are generally temporary in nature, since they are primarily made of ash and pumice, which are easily washed away by the sea, but some remain, and over time tend to merge with the parent island, leading to the formation of larger volcanic islands.

Iwoto is one of the Bonin Islands, which lie on the boundary between the Pacific and Philippine Plates, where the Pacific Plate is passing beneath the Philippine Plate as it is subducted into the Earth. As the Pacific Plate is subducted it is melted by the heat and pressure of the planet's interior. The lighter fractions of this melted material then rise through the overlying Philippine Plate as magma, fuelling the volcanoes of the various islands and island groups that lie along the boundary.

The movement of the Pacific and Philippine Plates beneath eastern Honshu. Laurent Jolivet/Institut des Sciences de la Terre d'Orléans/Sciences de la Terre et de l'Environnement.

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