Report on Suwanosejima (Japan) — July 2005

Bulletin of the Global Volcanism Network, vol. 30, no. 7 (July 2005)
Managing Editor: Edward Venzke

Suwanosejima (Japan) Eruptions during April 2004-July 2005 send plumes to varying heights

Please cite this report as:

Global Volcanism Program, 2005. Report on Suwanosejima (Japan). In: Venzke, E (ed.), Bulletin of the Global Volcanism Network, 30:7. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN200507-282030.

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Suwanosejima

Japan

29.638°N, 129.714°E; summit elev. 796 m

All times are local (unless otherwise noted)


Several small eruptions during December 2003 and January 2004 at Suwanose-jima produced ash plumes to unknown heights (BGVN 29:03). Little activity was observed during the first four months of 2004. From the end of April 2004 to the end of July 2005, numerous eruptions and explosions produced plumes reported by the Tokyo Volcanic Ash Advisory Center (VAAC), including some observed by pilots (table 3).

Table 3. Summary of activity at Suwanose-jima from April 2004 to July 2005 based on information from the Tokyo VAAC. "?" indicates data not reported or unknown.

[Skip text table]
    Date                   Time      Event                    Plume
                                                              Altitude (km)    Direction

    28 Apr 2004             --       ash emission                  3              SE
    01 May 2004            0906      explosion                     --             --
    07 Jun 2004             --       gas plume                     2               E
    08 Jun 2004             --       gas and ash                   2               E
    09 Jun 2004            1003      ash plume                     1.8             E
    09 Jun 2004            1300      ash plume                     --             --
    30 Jun-05 Jul 2004    various    several explosions        max 1.9            --
    30 Nov 2004            1607      eruption                      1.2            --
    20 Dec 2004             --       eruption                      1.8            SE
    21 Dec 2004             --       eruption                      --             SE
    22 Dec 2004             --       ash plume                     --             --
    24 Dec 2004             --       ash plume                     --             --
    25 Dec 2004             --       ash plume                     --             --
    27 Dec 2004             --       ash plume                     --             --
    29 Dec 2004             --       ash plume                     1.2            --
    01 Jan 2005             --       eruption                      --             --
    04 Jan 2005             --       eruption                      --             --
    06 Mar 2005             --       ash emission                  1.5            --
    08 Mar 2005             --       ash emission                  1.2            --
    09 Mar 2005             --       ash plume                     1.8            --
    26 Apr 2005             --       eruption                      1.2             E
    26 May-31 May 2005    various    several ash explosions    max 2.1            --
    01 Jun-06 Jun 2005    various    several ash explosions        1.8            --
    06 Jul 2005           various    several ash explosions        --             --
    27 Jul 2005             --       eruption with ash             0.8            --
    28 Jul 2005             --       ash plume                     2.4            --

Geologic Background. The 8-km-long, spindle-shaped island of Suwanosejima in the northern Ryukyu Islands consists of an andesitic stratovolcano with two historically active summit craters. The summit of the volcano is truncated by a large breached crater extending to the sea on the east flank that was formed by edifice collapse. Suwanosejima, one of Japan's most frequently active volcanoes, was in a state of intermittent strombolian activity from Otake, the NE summit crater, that began in 1949 and lasted until 1996, after which periods of inactivity lengthened. The largest historical eruption took place in 1813-14, when thick scoria deposits blanketed residential areas, and the SW crater produced two lava flows that reached the western coast. At the end of the eruption the summit of Otake collapsed forming a large debris avalanche and creating the horseshoe-shaped Sakuchi caldera, which extends to the eastern coast. The island remained uninhabited for about 70 years after the 1813-1814 eruption. Lava flows reached the eastern coast of the island in 1884. Only about 50 people live on the island.

Information Contacts: Tokyo Volcanic Ash Advisory Center, Japan Meteorological Agency (JMA), 1-3-4 Ote-machi, Chiyoda-ku, Tokyo 100, Japan (URL: http://www.jma.go.jp/JMA_HP/jma/jma-eng/jma-center/vaac/, Email: vaac@eqvol.kishou.go.jp).