Report on Karangetang (Indonesia) — 24 October-30 October 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 October-30 October 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Karangetang (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 24 October-30 October 2001. Smithsonian Institution and US Geological Survey.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
During 15-21 October volcanic activity at Karangetang continued to decrease, as it did the previous week, and the Alert Level was reduced from 3 to 2 (on a scale of 1-4). The number of volcanic earthquakes decreased compared to the previous week and no avalanche, tremor, or explosion earthquakes were recorded. Multiphase earthquakes, associated with lava dome growth, were detected. White plumes rose 400 m above main crater, and 50-100 m above Crater II. A "red reflection" was observed reaching up to 25 m above the crater.
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.