Report on Kuchinoerabujima (Japan) — November 2010

Bulletin of the Global Volcanism Network, vol. 35, no. 11 (November 2010)
Managing Editor: Richard Wunderman.

Kuchinoerabujima (Japan) Some periods of increased seismicity through 2009; white plumes

Please cite this report as:

Global Volcanism Program, 2010. Report on Kuchinoerabujima (Japan). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 35:11. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN201011-282050.

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Kuchinoerabujima

Japan

30.443°N, 130.218°E; summit elev. 639 m

All times are local (unless otherwise noted)


No eruptive activity has been reported at Kuchinoerabu-jima since a small eruption in September 1980 (SEAN 05:12). However, there have been many periods of elevated seismicity.

One such episode, beginning in early September 2008, prompted two increases in the hazard status by late October when the seismicity was accompanied by inflation and increased fumarolic activity near the summit (BGVN 33:09). The Alert Level remained at 3 (on a scale of 1-5) until 18 March 2009, when it was decreased to level 2. Sulfur dioxide emissions had decreased in January 2009, followed by a decrease in the rate of deformation.

Seismicity data during 2003-2009. Seismic data recorded by JMA between January 2003 and December 2006 indicted that the number of monthly volcanic earthquakes was typically below 200, with less than 30 tremor events. Seismicity was higher in March 2004, January-February, May, July-September, and November 2005, March-April, August, and October-December 2006, and February and April 2007 (table 1).

Table 1. Months with anomalous seismicity at Kuchinoerabu-jima between January 2003 and December 2009, showing numbers of earthquakes, tremors, and plume observations. Months with either more than 200 volcanic earthquakes or more than 30 tremors are shown, and months with earthquake swarms on specific days. All observed plumes throughout this period were white. Data courtesy of JMA.

[Skip text table]
Month         Earthquakes      Tremors     Days with    Plume height
                                            plumes          (m)	
                                            	
Mar 2004         315             48           --             --		
										
Jan 2005         346             59           --             --		
Feb 2005         234             36            4             40		
										
May 2005         100             35           --             --		
										
Jul 2005         136             58           --             --		
Aug 2005         228             40           --             --		
Sep 2005         201             10           --             --		
										
Nov 2005         205              7           --             --		
										
Mar 2006         292              7           --             --		
Apr 2006         289             11           --             --		
										
Aug 2006         221              2           --             --		
										
Oct 2006         291             31            1             10		
Nov 2006         479            100            5             30		
Dec 2006         201             32            5             10		
										
Feb 2007         174             65            2             10		
										
Apr 2007         127             57            2             10		
										
Sep 2008         186             49            1             30		
              70 on 4 Sep
              
Oct 2008         133             94           20            200		
Nov 2008         106             54           25            200		
Dec 2008         138             39           27            200		
										
Apr 2009         124             67           12            400		
May 2009         153             96           22            300
		
                 177              6       
Sep 2009      75 on 27 sep      28 Sep        10            200
             ~750 on 28-29    and 30 Sep
             
Oct 2009         131             32           10            200	
                             all 1-6 Oct	

A seismic swarm consisting of 70 events on 4 September 2008 resulted in the Alert Level increase already reported. The months of September-December 2008 included high numbers of tremor episodes (table 1). Large numbers of tremors were recorded again in April-May 2009. Seismicity decreased after that time, until an earthquake swarm was recorded during 27-29 September 2009 (about 150 earthquakes). Tremor events also increased briefly, with 38 between 28 September and 6 October 2009. White fumarolic plumes rising from the summit area increased in height (up to 400 m) and frequency (every 1-2 days) after September 2008 through 2009.

Geologic Background. A group of young stratovolcanoes forms the eastern end of the irregularly shaped island of Kuchinoerabujima in the northern Ryukyu Islands, 15 km west of Yakushima. The Furudake, Shindake, and Noikeyama cones were erupted from south to north, respectively, forming a composite cone with multiple craters. The youngest cone, centrally-located Shintake, formed after the NW side of Furutake was breached by an explosion. All historical eruptions have occurred from Shintake, although a lava flow from the S flank of Furutake that reached the coast has a very fresh morphology. Frequent explosive eruptions have taken place from Shintake since 1840; the largest of these was in December 1933. Several villages on the 4 x 12 km island are located within a few kilometers of the active crater and have suffered damage from eruptions.

Information Contacts: Japan Meteorological Agency (JMA), Otemachi, 1-3-4, Chiyoda-ku Tokyo 100-8122, Japan (URL: http://www.jma.go.jp/, http://www.seisvol.kishou.go.jp/tokyo/STOCK/kaisetsu/English/level.html)