Report on Karangetang (Indonesia) — 26 November-2 December 2008
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
26 November-2 December 2008
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Karangetang (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 26 November-2 December 2008. 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 on 28 November seismicity from Karangetang increased and indicated rockfalls. White plumes rose from summit craters I and II to approximate altitudes of 1.8-2.2 km (5,900-7,200 ft) a.s.l. On 29 November white and brownish plumes rose to an altitude of 1.8 km (5,900 ft) a.s.l. Incandescent rockslides from the main crater traveled 250 m S towards the Bahembang River, 250 m W towards the Beha Timur River, and 500-1,000 m S towards the Keting River. Thunderous noises were reported. On 30 November, fog prevented visual observations; the seismic network recorded 160 rockfalls. On 1 December, incandescent rockslides traveled 250 m S towards the Bahembang River, 750 m W towards the Beha Timur River, and 500-1,500 m S towards the Keting River. On 2 December, the Alert Level was raised to 3 (on a scale of 1-4) due to the continuation of elevated seismicity, run-out distances of incandescent rockslides, and height of incandescent material ejected from the summit.
Based on analysis of satellite imagery and information from CVGHM, the Darwin VAAC reported that on 2 December an ash plume from Karangetang rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted W.
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.