Saturday 11 February 2023

Eruption on Mount Sakurajima in Kagoshima Prefecture, Japan.

Mount Sukurajima, a 1117 m high stratovolcano (cone-shaped volcano made up of layers of ash and lava) in Kagoshima Prefecture on Kyūshū Island, Japan, erupted on Wednesday 8 February 2023, according to the Kagoshima Meteorological Office. The volcano began erupting from the Showa Crater on the east side of the Minamidake Peak (the southernmost of the volcano's three summits), slightly after 10.50 am local time, and had by 11.10 am had produced an ash column over a kilometre high. The eruption was not unexpected, with volcanologists having detected swelling beneath the crater from 14 January 2023. A two kilometre exclusion zone was put in place around the crater as a precaution against pyroclastic flows.

An eruption on Mount Sakurajima, Japan, on 8 February 2023. Kyodo News Agency.

Japan has a complex tectonic situation, with parts of the country on four different tectonic plates. Kyūshū Island lies at the northeast end of the Ryukyu Island Arc, which sits on top of the boundary between the Eurasian and Philippine Plates. The Philippine Plate is being subducted beneath the Eurasian Plate, in the Ryukyo Trench, to the Southeast of the Islands. As it is drawn into the interior of the Earth, the tectonic plate is partially melted by the heat of the Earth's interior, and liquid magma rises up through the overlying Eurasian Plate to form the volcanoes of the Ryukyu Islands and Kyūshū.

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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