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Report on Karangetang (Indonesia) — October 2003


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

Karangetang (Indonesia) White gas emissions and glow during October, but decreased seismicity

Please cite this report as:

Global Volcanism Program, 2003. Report on Karangetang (Indonesia) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 28:10. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200310-267020



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

All times are local (unless otherwise noted)

Explosive activity has been common at Karangetang in recent years, producing ashfall and lava avalanches as recently as May and June 2003 (BGVN 28:05 and 28:07). However, Karangetang was not included in reports by the Volcanological Survey of Indonesia (VSI) between 16 June and 28 September 2003. A report for the week of 29 September-5 October indicated that there had been a decrease in multiphase and emissions earthquakes compared to the previous week (table 9). At that time white gas emissions were observed rising 400 m above the S crater and 50 m above the N crater. Red glow was seen at night over the S crater that week. No lava avalanches occurred. Similar observations were reported through 19 October. Although surface observations of activity were consistent, seismic data showed that shallow volcanic earthquakes increased and emission events decreased during 6-19 October. The hazard status remained at Alert Level 2 (on a scale of 1-4) through at least 19 October.

Table 9. Seismicity at Karangetang during 2 June-19 October 2003. No data was available between 16 June and 28 September. Courtesy of VSI.

Date Deep volcanic (A-type) Shallow volcanic (B-type) Multiphase Emission Tectonic
02 Jun-08 Jun 2003 11 348 233 46 26
09 Jun-15 Jun 2003 32 438 228 21 20
29 Sep-05 Oct 2003 15 84 50 121 38
06 Oct-12 Oct 2003 19 103 33 74 32
13 Oct-19 Oct 2003 18 135 54 72 33

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. 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 (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/).