Report on Karangetang (Indonesia) — January 1979
Scientific Event Alert Network Bulletin, vol. 4, no. 1 (January 1979)
Managing Editor: David Squires.
Karangetang (Indonesia) Occasional explosions since October
Please cite this report as:
Global Volcanism Program, 1979. Report on Karangetang (Indonesia). In: Squires, D. (ed.), Scientific Event Alert Network Bulletin, 4:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197901-267020.
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
Three explosions from the summit crater occurred during October and two others were observed at night during November and early December. Ashfalls reached Ulu, 6 km SE of the summit (figure 1), where ~0.5 mm of ash was deposited.
A 10-minute eruption beginning at 1730 on 15 December produced a thick tephra column that rose 600-700 m above the summit and dropped more than 0.5 mm of ash on Ulu. Sharp explosion sounds were clearly audible from the temporary observatory at Tarorane, about 5 km from the summit. Volcanic tremors were frequently felt, but none were recorded at Tarorane.
Vapor emission from the 1976 vents has stopped, but a solfatara ~ 50 m above the upper vent emitted a thin stream of bluish gas.
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.
Information Contacts: A. Sudradjat, M. Kamid, VSI.