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Mount Asama erupts 2 February 2009

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Mount Asama, 2 February 2009.

Mount Asama in Japan fulfilled the JMA forecast by erupting on a relatively small scale today, producing a steam-and-ash plume to altitudes of around 2 km and throwing rocks as far as 1km from the vent. Light ashfall took place over parts of Tokyo and reached as far as Yokohama. The Tokyo VAAC had reports (based on estimates) of ash up to altitudes of 10000 to 15000 ft (3-4.5 km), dispersing to the south-east. The BBC has a video showing aerial views of the summit which must have been taken soon after the eruption.

Meanwhile Sakura-jima on Kyushu in the south of Japan has also erupted several times over the last few hours, producing ashfall mainly into the sea. Sakura-jima is highly active, with frequent explosions producing ash plumes, and residents of the nearby city of Kagoshima took the latest activity in their stride: ‘we did not note anything out of the ordinary affecting daily activity’, said a local official.

Webcam views of Asama can be found here and here (thanks to Boris Behncke and Stefan Keuttel for this information). The image at the top is Asama erupting, 02:00, 2 February 2009 (thanks to Stefan Keuttel; original here).

UPDATE: The Japan Meteorological Agency is pleased that this eruption of Mount Asama has proved to be a success for its new volcano alert system, introduced in December 2007, reports The Japan Times.

News
Japan volcano Mount Asama erupts, no major damage – Reuters, 2 February 2009
Volcano erupts near Tokyo raining ash down on city – Associated Press, 2 February 2009
Ash falls on Tokyo as volcanoes erupt – AFP, 2 February 2009
Volcano erupts close to Tokyo – BBC News, 2 February 2009
Volcano erupts in Japan – BBC News, 2 February 2009 (video)

Information
Global Volcanism Program: Asama – summary information for Asama (0803-11=)
Global Volcanism Program: Sakura-jima – summary information for Sakura-jima (0802-08=)
Japan Meteorological Agency – English-language homepage for the JMA
Volcano Research Center, University of Tokyo – English-language homepage for the VRC

The Volcanism Blog

Heightened alert at Mount Asama 1 February 2009

Posted by admin in activity reports, Asama, Japan, volcano monitoring.
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'Earthquake and Eruption of the Mountain of Asama-yama, in the province of Sinano', Isaac Titsingh, London, 1822 (Courtesy of the University of Texas Libraries, The University of Texas at Austin).

The Japan Meteorological Agency has raised the alert level for Mount Asama, the most active of Honshu’s many volcanoes, after detecting increased seismic activity.

Press reports quote JMA official Sadayuki Kitagawa as warning that ‘Mount Asama could erupt within two days, spewing rocks and ash’, and that ‘there are prospects for an eruption that could thrown volcanic rocks to a distance of around 4 kilometres’. Up to 45,000 people could be affected by the current alert, and local officials are warning people to be ready for evacuation.

Asama has erupted frequently in recent years, most recently in September 2004, but without fatalities or widespread destructive effects. The volcano’s last destructive eruption was in May-August 1783, a VEI4 event which devastated 500 square kilometres and left around 1200 people dead.

Image: ”Earthquake and Eruption of the Mountain of Asama-yama, in the province of Sinano’, from Isaac Titsingh, Illustrations of Japan: Consisting of Private Memoirs and Anecdotes of the Reigning Dynasty of the Djogouns, or Sovereigns of Japan (London, 1822). Courtesy of the University of Texas Libraries, The University of Texas at Austin. [Source]

News
Japan warns of eruptions at volcanoInternational Herald Tribune, 1 February 2009
Japan on heightened alert for Mount Asama eruption – Reuters, 1 February 2009
Japan warns of volcano eruption within 48 hours – Telegraph.co.uk, 1 February 2009

Information
Global Volcanism Program: Asama – summary information for Asama (0803-11=)
Japan Meteorological Agency – English-language homepage for the JMA
Volcano Research Center, University of Tokyo – English-language homepage for the VRC

The Volcanism Blog

Japan: Kurikoma activity raises questions 17 June 2008

Posted by admin in activity reports, blogs, geoscience, Japan, Kurikoma.
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Hot gas plumes thought to consist of volcanic gases have been detected 7km south-west of the summit of Mt Kurikoma, a 1628m stratovolcano in northern Honshu (see Erik’s Eruptions blog for more). Kurikoma last erupted in 1950, and has in general a rather sketchy eruptive history.

The volcano is in the area affected by Friday’s 6.8M earthquake, so are these phenomena related? Here’s what the Japanese press report says:

Associate Prof. Sadato Ueki of Tohoku University’s Research Center for the Prediction of Earthquakes and Volcanic Eruptions said the plumes might be volcanic gases rising to the Earth’s surface.

‘There’s a possibility that volcanic gases that had been confined below ground are gushing out through fissures in the mountain created by the earthquake,’ he said.

Ueki said it was also possible that the plumes were steam coming from underground hot water channels that had their course diverted by the earthquake.

But the professor ruled out the possibility of increased volcanic activity on Mt. Kurikoma, saying that the plumes were very far from the summit of the volcano.

So the professor is suggesting the plumes might be by-products of the earthquake. Kim at All of My Faults Are Stress-Related similarly asks ‘Did the earthquake … cause Kurikoma to start acting up?’, but also observes that this was a rather unusual earthquake. It was along a thrust fault, but it was in Honshu’s volcanic arc, which is not where you would expect a thrust earthquake to be. Kim asks whether the quake itself might be the result of local magmatism: ‘the fault mechanism isn’t surprising. But the location is. Is this a case where the magmatism created a weaker zone in the crust and allowed thrust faulting to take place?’

It will be interesting to watch what happens.

Information
Global Volcanism Program: Kurikoma – summary information for Kurikoma (0803-21=)

News
Hot gas plumes detected at Mt. KurikomaDaily Yomiuri Online, 17 June 2008

The Volcanism Blog