Report on Soputan (Indonesia) — October 2003

Bulletin of the Global Volcanism Network, vol. 28, no. 10 (October 2003)
Managing Editor: Edward Venzke.

Soputan (Indonesia) Ash explosion and lava flows on 31 August

Please cite this report as:

Global Volcanism Program, 2003. Report on Soputan (Indonesia). In: Venzke, E (ed.), Bulletin of the Global Volcanism Network, 28:10. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN200310-266030.

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Soputan

Indonesia

1.112°N, 124.737°E; summit elev. 1785 m

All times are local (unless otherwise noted)


Increased activity during 18-22 July 2003 at Soputan consisted of frequent ash explosions and large glowing lava avalanches (BGVN 28:08). Seismicity from August through mid-October was dominated by avalanche events, with a few tectonic earthquakes (table 4). White gas emissions in this period were commonly seen rising 25-50 m above the crater, but were also reported as high as 1,000 m in late August and September. On 31 August there was ash explosion accompanied by ejection of incandescent material. The ash column reached 1,000 m above the summit. Lava flowed 750 m down the SW slope, and some descended to the N. Volcanic tremor that week (18-31 August) had an amplitude of 10-38 mm. The hazard status remained at Alert Level 2 (on a scale of 1-4) through 19 October.

Table 4. Seismicity at Soputan, 18 August-19 October 2003. Courtesy of VSI.

[Skip text table]
    Date (2003)       Avalanche      Tectonic
                     Earthquakes    Earthquakes

    18 Aug-31 Aug        71             --
    29 Sep-05 Oct        80             12
    06 Oct-12 Oct        30              8
    13 Oct-19 Oct        62              9

Geologic Background. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Riendengan-Sempu, which some workers have included with Soputan and Manimporok (3.5 km ESE) as a volcanic complex. It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.

Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani, and Suswati, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (Email: dali@vsi.esdm.go.id, URL: http://www.vsi.esdm.go.id/).