Report on Karangetang (Indonesia) — 23 March-29 March 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
23 March-29 March 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, 23 March-29 March 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 21-23 March incandescent material from Karangetang was ejected 50-75 m above the crater. Lava flows traveled as far as 2 km and collapses from the lava-flow fronts generated avalanches that moved down the flanks up to 300 m further. On 24 March lava was incandescent in areas 1.5 km away from the crater. Incandescent material from the lava-flow fronts rolled an additional 200-500 m down the flanks. Incandescent material was again ejected 75 m above the crater. Later that day, due to decreased seismicity and a decline in the lava-flow effusion rate, the Alert Level was lowered to 3 (on a scale of 1-4).
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.