Report on Karangetang (Indonesia) — 27 February-5 March 2002
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 February-5 March 2002
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2002. Report on Karangetang (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 27 February-5 March 2002. Smithsonian Institution and US Geological Survey.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
VSI reported that at Karangetang during 25 February-3 March small volcanic plumes were emitted, a "red reflection" extended 25 m above the crater, and seismicity was high although it decreased in comparison to the previous week. A pilot report to the Darwin VAAC stated that a layer of apparent ash was seen on 5 March at 1544. The layer was located 18.5-37 km from Karangetang at an altitude near 7.5 km (winds in the area suggest ash was at least as high as ~5.5 km). The Karangetang Volcano Observatory reported that an explosion at 1344 the same day rose 1 km above the volcano's summit (2.8 km a.s.l.). No ash was visible in satellite imagery under clear conditions; the ash layer may have been too thin to detect. The volcano remained at Alert Level 2 (on a scale of 1-4).
Geologic Background. 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.