Japan has a (temporary) new island

An underwater volcanic eruption near Japan has created a new, roughly crescent-shaped island some 1,200 kilometers south of Tokyo - although the new landmass will likely only be temporary. According to the Japan Meteorological Agency, the submarine eruption — the volcano’s first in over a decade — began on August 13, 2021.

Niijima (新島), meaning 'new island', has a diameter of 1 kilometre and has emerged five kilometres north of Minami-Iōtō (南硫黄島), better known as South Iwo Jima or New Sulfur Island, amid the Nanpō Islands (南方諸島) that lie south of the Japanese archipelago.

The island formed as a result of a powerful eruption of Fukutoku-Okanoba, a submarine volcano which was only discovered when it erupted in 1904. The eruption produced a spectacular mushroom plume of steam and ash up to 16 kilometres altitude, quickly created a new cone that has now breached the surface.

When the eruption reached the surface, it created violent steam explosions as hot magma interacted with the surrounding sea water (known as phreatomagmatic or Surtseyan activity), ejecting billowing white steam plumes and dark jets of water, steam and rock fragments.

The last confirmed eruptions of the volcano occurred in 2010, 2005-07, 1986, 1914, and during 1904-05. During some of these, temporary islands were formed that subsequently were eroded again by the relentless waves of the ocean.

Whether the new island will become a lasting one will depend on the near future. At the moment, it has a flat crescent-shape with a breached bay above the vent and seems to be composed only of fragmented material (ash and blocks), which are not stable enough to resist wave erosion for too long. If activity continues and produces lava flows that manage to “seal” some of the new land, its chances of long-term survival will increase greatly.