Report on Lokon-Empung (Indonesia) — 26 March-1 April 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 March-1 April 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, 26 March-1 April 2003. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
VSI decreased the Alert Level at Lokon-Empung on 24 March from 3 to 2 (on a scale of 1-4) due to a decrease in volcanic activity. During 17-23 March, "white-thick ash emissions" rose to ~300 m above Tompaluan crater, ash explosions occurred, and there was a significant decrease in emission earthquakes compared to the previous week. On 27 March at 0156 an explosion ejected ash to 1.5 km and incandescent volcanic material to 400 m above the crater. An ash cloud drifted S and ash fell around the summit. Ash was not visible on satellite imagery. Lokon-Empung remained at Alert Level 2.
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.