Report on Karangetang (Indonesia) — December 2000
Bulletin of the Global Volcanism Network, vol. 25, no. 12 (December 2000)
Managing Editor: Richard Wunderman.
Karangetang (Indonesia) Explosions generate ash plumes, ashfall, lava flows and avalanches
Please cite this report as:
Global Volcanism Program, 2000. Report on Karangetang (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 25:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200012-267020
2.781°N, 125.407°E; summit elev. 1797 m
All times are local (unless otherwise noted)
Heightened activity continued at Karangetang in late December 2000-late January 2001, following a year of frequent activity in 2000 (BGVN 25:11). The main crater and Crater II sent a white, variably-thick ash plume up to 600 m above the summit during 19-25 December. Plume illumination up to 150 m above the craters was visible at night. Lava flows occurred on 21-22 December and reached as far as 1,250 m laterally along the SW flank. The seismic record also showed increased activity with multi-phase earthquakes predominating.
Activity, however, tailed off during 26 December-1 January before increasing again with renewed vigor from 2 to 8 January. At 1258 on 2 January an explosion produced a white-gray ash plume that rose ~500 m above the summit. At 1845 on the same day, workers observed a glowing lava avalanche issuing from the main crater and moving 50 m from the summit down toward the Naitu River. A larger explosion on 7 January sent gray ash 1,500 m above Karangetang. A coeval Strombolian eruption cloud rose 200 m. Ashfall occurred W of the volcano, coating Pahe, Lehi, Mini, and Kinali villages. Lava flowed down to the Tanitu River as far a 1 km from the summit. Tectonic earthquakes dominated seismicity during the week, and a significant number of tremor earthquakes also occurred.
A minor explosion occurred on 10 January; ash rose and subsequently fell back into the crater. Tectonic earthquakes again overshadowed all other types during 9-15 January. At 0845 on 17 January an explosion generated a small ash plume and a lava avalanche. Ash fell on Salili and Beong villages; lava flowed down both the E and W flanks of the volcano. Seismicity remained elevated with earthquake distributions similar to the previous week. The VSI maintained a hazard status of 2 (on a scale of 1-4) for Karangetang throughout the report period.
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.
Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).