TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 65 (No. 6), pp. 489-504, 2013

The 2011 eruptive activity of Shinmoedake volcano, Kirishimayama, Kyushu, Japan—Overview of activity and Volcanic Alert Level of the Japan Meteorological Agency—

Koji Kato1,2 and Hitoshi Yamasato2

1Fukuoka District Meteorological Observatory, Japan Meteorological Agency, 1-2-36, Ohori, Chuo, Fukuoka 810-0052, Japan
2Seismological and Volcanological Department, Japan Meteorological Agency, 1-3-4, Otemachi, Chiyoda, Tokyo 100-8122, Japan

(Received November 9, 2012; Revised May 8, 2013; Accepted May 13, 2013; Online published July 8, 2013)

Abstract: Following several years of small phreatic eruption events, Shinmoedake volcano in Kyushu, Japan, began a new phase of activity on 19 January 2011. The eruption commenced with a small phreatomagmatic event followed by subplinian events on 26 and 27 January. Lava emerged as a dome in the summit crater on 27 January and filled the crater until the beginning of February. During the subplinian events and lava dome growth, deflation of the deep magma chamber was observed by tiltmeters and GPSνll. Eruptive activity began to decrease in March 2011 and no eruptive event occurred after the 7 September 2011 event. In response to the eruption, the Japan Meteorological Agency (JMA) issued warnings repeatedly to prepare local people and infrastructures around Shinmoedake. JMA did not raise the Volcanic Alert Level before the first subplinian event, because of a lack of clear precursory signals. We conclude that a large amount of magma moved in the shallow Shinmoedake plumbing system for a short time, based on a number of geophysical observations. It is important to detect magma movement and understand eruptive phenomena quickly in order to mitigate risks of volcanic hazards.
Key words: Shinmoedake, Kirishimayama, Volcanic Alert Level.

Corresponding author E-mail: koji-kato@met.kishou.go.jp

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