Report on Karangetang (Indonesia) — 1 June-7 June 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 1 June-7 June 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Karangetang (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 1 June-7 June 2011. 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 25 March-5 June seismic activity at Karangetang decreased along with the potential threat of avalanches and pyroclastic flows. During 1 May-5 June no pyroclastic flows were observed. Lava flowed 200 m down the flanks and produced incandescent material from the flow fronts that traveled an additional 1.5-1.8 km. Bluish-white emissions rose as high as 500 m from the main crater and incandescence from the crater was observed at night. Lava flow and avalanche activity decreased on 19 May. The Alert Level was lowered to 2 (on a scale of 1-4) on 6 June.
Geologic Background. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, north 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 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 has also produced pyroclastic flows.