Report on Lokon-Empung (Indonesia) — 22 July-28 July 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 July-28 July 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Lokon-Empung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 July-28 July 2015. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
PVMBG reported that during 15-22 July observers at the Lokon Observation Post in Kakaskasen Tomohon, North Sulawesi (4 km from the crater) reported that, although inclement weather sometimes obscured views of Lokon-Empung's Tompaluan Crater, white plumes were observed rising as high as 75 m above the crater. The number of volcanic earthquakes declined but still remained higher than levels recorded during 25 May-10 July. Signals indicating emissions were occasionally detected. The Alert Level remained at 3 (on a scale of 1-4). Residents and tourists were reminded not to approach Tompaluan Crater within a radius of 2.5 km.
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.