Report on Lokon-Empung (Indonesia) — 5 February-11 February 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 February-11 February 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Lokon-Empung (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 5 February-11 February 2003. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
Starting at the beginning of the report week (3-9 February), there was an increase in seismicity and surface activity at Lokon-Empung in comparison to the previous week. There were more emission, and deep and shallow volcanic earthquakes and ash emissions. On 8 February at 0443 an ash explosion was accompanied by the ejection of incandescent volcanic material. A thick ash cloud rose to 1.4 km over the crater and 0.5-1 mm of ash was deposited S of the volcano in the villages of Kayau, Tara-tara I and II, and Woloan II and III. At this time the Alert Level was raised from 2 to 3 (on a scale of 1-4).
Geologic Background. The twin volcanoes Lokon and Empung, rising about 800 m above the plain of Tondano, are among the most active volcanoes of Sulawesi. Lokon, the higher of the two peaks (whose summits are only 2 km apart), has a flat, craterless top. The morphologically younger Empung volcano to the NE has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century, but all subsequent eruptions have originated from Tompaluan, a 150 x 250 m wide double crater situated in the saddle between the two peaks. Historical eruptions have primarily produced small-to-moderate ash plumes that have occasionally damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred. A ridge extending WNW from Lokon includes Tatawiran and Tetempangan peak, 3 km away.