Tuesday 30 June 2015

Japan restricts access to Mount Hakone after small eruption.

Authorities in Japan have closed off part of Mount Hakone, a popular tourist resort in Kanagawa Prefecture with hot springs and views of Mount Fuji, following a small eruption on Monday 29 June 2015. Nobody was injured in the event, in which a small amount of ash was produced slightly before 7.00 am, and was preceded by a Magnitude 3.3 Earthquake, but about 40 people were evacuated from the area due to the possibility of a phreatic eruption (explosion caused by water coming into contact with hot lava and vapourising).

Ash cloud over Mount Hakone. Reuters.

The Hakone area is noted for its hot springs, which are caused by water coming into contact with burried hot rocks, then rising to the surface, however Earthquakes near volcanoes are often caused by liquid magma moving through chambers beneath the volcano, and can be symptoms of future eruptions. In the case of Hakone there is a concern that magma closerto the surface my come into contact with liquid water, leading to explosions capable of throwing debris into the air at the surface.

The location of Mount Hakone. Google Maps.

Japan has a complex tectonic situation, with parts of the country on four different tectonic plates. Eastern Honshu area lies on the boundary between the Pacific, Eurasian and Philipine Plates, where the Pacific Plate is passing beneath the Eurasian and Philipine Plates as it is subducted into the Earth. This is not a smooth process; the rocks of the two plates constantly stick together, only to break apart again as the pressure builds up, causing Earthquakes in the process. 

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.

Mount Hakone is located directly on the Bonin Arc, a chain of volcanoes fed by liquified material from the Pacific Plate which is melted by the heat of the Earth's interior and rises through the overlying Eurasian Plate.

See also...

Authorities in Kanagawa Prefecture have closed off an area of Mount Hakone, a popular tourist destination, following a rise sharp in seismic activities since 26 April 2015. An area of around 300 m around the...

The Japan Meteorological Agency (which also monitors seismic activity) recorded a Magnitude 5.7 Earthquake at a depth of 50 km off the coast of Iwate Prefecture, slightly after 1.45 pm Japan Standard Time (slightly after 4.45 am GMT) on Tuesday 17 February 2015. There...

The Japan Meteorological Agency (which also monitors seismic activity) recorded a Magnitude 6.8 Earthquake at a depth of 10 km in Nagano...

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