Report on Lokon-Empung (Indonesia) — 12 February-18 February 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 February-18 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, 12 February-18 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)
On 10 February at 2219 an ash explosion occurred at Lokon-Empung, but the height of the resultant ash cloud could not be determined due to heavy rain. On 12 February, mainly during 0100-1000, there was a significant increase in volcanic earthquakes. At 1048 an explosion occurred, followed by seismic data indicating a larger explosion at 1102. On 12 February during 0800-1100 the Alert Level was raised from 3 to 4 (the highest level). Tremor was continuously recorded during 1255 on the 12th to 0046 the following day. According to the Darwin VAAC, an explosion occurred on 19 February at 0403 that produced a plume to 500 m above the summit.
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.