Report on Lokon-Empung (Indonesia) — 28 December-3 January 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 December-3 January 2012
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, 28 December-3 January 2012. 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 on 27 December seismic activity at Lokon-Empung suggested that an eruption had occurred, but fog prevented visual observations of the crater area. CVGHM noted on 28 December that the Alert Level remained at 3 (on a scale of 1-4), and reminded residents and tourists to not approach within a 2.5 km radius of the crater. Based on information from CVGHM, the Darwin VAAC reported that on 29 December an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l.
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.