Report on Karangetang (Indonesia) — 26 September-2 October 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 September-2 October 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Karangetang (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 26 September-2 October 2001. Smithsonian Institution and US Geological Survey.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
During 17-23 September lava flows and lava avalanches rarely occurred at Karangetang. Small white-colored emissions rose ~500 m above the main crater and 50-200 m above Crater II. A 10- to 100-m-high "red reflection" was visible above the volcano. Seismic activity decreased in comparison to the previous week and was dominated by multiphase and avalanche earthquakes. During 24-30 September seismic activity continued to decrease and few lava avalanches were observed emanating from main crater. Plumes rose 400 m above the summit of the main crater and 50-100 m above Crater II. A 25-m-high "red reflection" was observed. The Alert Level remained at 3 (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.