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Report on Karangetang (Indonesia) — November 2003


Bulletin of the Global Volcanism Network, vol. 28, no. 11 (November 2003)
Managing Editor: Edward Venzke.

Karangetang (Indonesia) Ash explosion on 28 October, then decreased seismicity

Please cite this report as:

Global Volcanism Program, 2003. Report on Karangetang (Indonesia) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 28:11. Smithsonian Institution.



2.781°N, 125.407°E; summit elev. 1797 m

All times are local (unless otherwise noted)

White gas emissions and glow were reported at Karangetang during October 2003. The Volcanological Survey of Indonesia (VSI) reported continuing activity over the period 26 October-30 November, with white gas plumes rising 350-400 m above the S crater rim and 50-150 m above the N crater. On 28 October an ash explosion produced a 2,000-m-high column with ashfall reaching the sea to the E and a lava avalanche toward the Batu Awang area, 750 m from the summit. Except for the week of 17-23 November, local seismicity decreased compared to the first half of October (table 10). The hazard status remained at Alert Level 2 (on a scale of 1-4).

Table 10. Seismicity at Karangetang during 27 October-30 November 2003. One explosion and one avalanche also occurred during the week of 27 October-2 November. Courtesy of VSI.

Date Deep volcanic (A-type) Shallow volcanic (B-type) Multiphase Emission Tectonic
27 Oct-02 Nov 2003 18 64 10 24 43
03 Nov-09 Nov 2003 9 96 7 12 53
10 Nov-16 Nov 2003 3 52 10 23 106
17 Nov-23 Nov 2003 25 135 16 42 47
24 Nov-30 Nov 2003 15 79 34 29 130

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