Report on Karangetang (Indonesia) — December 2002
Bulletin of the Global Volcanism Network, vol. 27, no. 12 (December 2002)
Managing Editor: Richard Wunderman.
Karangetang (Indonesia) 500-m plumes and ~ 1.5-km glowing lava avalanche; Alert Level increased
Please cite this report as:
Global Volcanism Program, 2002. Report on Karangetang (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 27:12. Smithsonian Institution.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
During September-29 December 2002, seismicity at Karangetang was dominated by emission, multiphase and tectonic earthquakes (table 6). The S crater nearly always issued "white, thin ash plumes" that reached up to 500 m above the rim. At night, a light plume was visible rising 25-100 m. Loud noises were heard frequently, and the N crater emitted a "thin white ash plume" to 50 m. No ashfall was reported.
|Date||Deep volcanic (A-type)||Shallow volcanic (B-type)||Explosion||Multiphase||Emission||Tectonic||Avalanche|
|09 Sep-15 Sep 2002||14||24||0||94||299||46||--|
|16 Sep-22 Sep 2002||28||27||0||82||246||39||--|
|23 Sep-29 Sep 2002||22||26||1||20||116||75||--|
|30 Sep-06 Oct 2002||14||4||0||38||88||54||98|
|07 Oct-13 Oct 2002||19||13||--||30||67||89||43|
|14 Oct-20 Oct 2002||7||22||1||30||146||34||10|
|21 Oct-27 Oct 2002||12||34||--||23||114||65||--|
|28 Oct-03 Nov 2002||18||154||--||147||49||24||--|
|04 Nov-10 Nov 2002||15||29||--||90||21||69||--|
|11 Nov-18 Nov 2002||12||40||1||75||28||70||--|
|19 Nov-24 Nov 2002||15||116||--||94||1||46||--|
|23 Dec-29 Dec 2002||10||26||1||168||17||25||--|
During 9 September-13 October glowing avalanches flowed 25-250 m toward Nanitu river (West Siau), and toward Beha river as far as 400 m from the crater rim. By the week of 14-20 October, the lava avalanches extended ~1.5 km toward the Nanitu river, 1.0 km toward the Beha river (West Siau), and 750 m toward the Kahetang river.
On 12 September loud noises were accompanied by a 50-m-high gray ash plume. During 5-6 October, there were 2 volcanic tremor events. On 19 October at 1759 an explosion ejected glowing material to a height of 500 m; it landed inside the crater. A gray-black ash plume reached up to 750 m, drifted to the N, and fell on the sea.
Activity decreased during November, and loud sounds were rarely heard. On 15 November at 0248 an ash explosion produced glowing material up to ~200 m that fell around the crater. Some of the material entered the Batang, Beha, and Keting rivers, located 300-350 m away. Ash fell around Salili, Beong, Hiu, Ondong, Pehe, and Paniki villages to the SW. The Alert Level remained at level 3 through at least 29 December (on a scale of 1 to 4).
Geological Summary. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi island. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented in the historical record (Catalog of Active Volcanoes of the World: Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows.
Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).