On 9 August 2013 the Japan Meteorological Agency reported a 50 minute eruption on Sakurajima Volcano, which is one of Japan's most active and sits on an island in Kagoshima Bay, Kyushu Island, which produced a 3.5 km high ash column, as well as throwing tephra (lumps of rock) up to 800 m from the crater. This is not atypical behavior on Sakurajima, which has erupted over a dozen of time already this month and probably over a hundred times this year, producing ash columns in excess of 5 km high in March and June, and which hasn't had a quiet period of more than a few days since 2008.
An eruption on Sakurajima in July 2013. Volcano Discovery.
Japan has a complex tectonic environment with four plates underlying parts of the Islands; in addition to the Pacific in the east and the Othorsk in the North, there are the Philipine Plate to the south and the Eurasian Plate to the West. Kyushu 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 volcanos of the Ryukyu Islands and Kyushu.
The location of the Sakurajima Volcano. Google Maps.
See also Magnitude 6.0 Earthquake east of the Oshika Peninsula, Japan, Eruption on Tori-shima, Magnitude 6.0 Earthquake in southern Japan, Magnitude 7.3 Earthquake off the coast of Japan and Japan shaken by pair of major Earthquakes.
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