Report on Lokon-Empung (Indonesia) — 3 August-9 August 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
3 August-9 August 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Lokon-Empung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 3 August-9 August 2011. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
CVGHM reported that during 24 July-8 August seismicity decreased at Tompaluan crater, in the saddle between the Lokon-Empung peaks, with a drastic reduction on 26 July. During 27 July-8 August white plumes rose 100-400 m above the crater. The Alert Level remained at 3 (on a scale of 1-4). Residents and tourists were not permitted within a 3-km radius of the crater.
Geological Summary. 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.