Report on Karangetang (Indonesia) — 22 September-28 September 2010
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 September-28 September 2010
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2010. Report on Karangetang (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 September-28 September 2010. Smithsonian Institution and US Geological Survey.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
CVGHM reported that during 1-7 September lava seen from the observation post (5 km SSW) traveled 75 m down Karangetang's flanks. Avalanches traveled as far as 1.5 km down the Batang (S), Batu Awang (E), and Nanitu drainages. Incandescent material was ejected 350 m above the crater. During 8-21 September lava traveled 500 m down the flanks. Avalanches originating from the end of the lava flow traveled as far as 2 km down the Batang, Kahetang (E), and Nanitu drainages. During 18-20 September material was ejected 300-500 m above the crater. Ashfall was reported in areas to the NW. On 21 and 22 September incandescent material traveled down multiple drainages. Strombolian activity was observed on 22 September; material ejected 50 m high fell back down around the crater. That same day the Alert level was raised to 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.