Report on Karangetang (Indonesia) — 19 July-25 July 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 19 July-25 July 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Karangetang (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 19 July-25 July 2006. Smithsonian Institution and US Geological Survey.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
The Alert Status of Karangetang was raised on 22 July from 3 to 4 (on a scale of 1-4) due to a further increase in eruptive activity since the last reporting period. On 20 July, lava flows were observed moving E toward the Kahetang and Batu Awang rivers at a maximum distance of 1.8 km from the vent, towards the Keting river at unknown location and distance, and S towards the Bahembang river at a maximum distance of 2 km. On 21 July, a pyroclastic flow originating from the upper S flank traveled 2.5 km toward the Stone river (unknown direction) and was followed by lava flows that traveled toward the Keting river and E towards the Kahetang river at a maximum distance of 2 km. A "thin white smoke" was seen at a height of ~350 m above the summit (7,000 ft a.s.l.). Lava flows traveled a maximum distance of ~2.3 km towards the Keting river and S towards the Bahembang river during 22-23 and 25 July.
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.