Report on Lokon-Empung (Indonesia) — 2 April-8 April 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 2 April-8 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, 2 April-8 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)
Beginning on 31 March the number of volcanic earthquakes at Lokon-Empung was relatively high. On 1 April at 2242 an explosion produced an ash column to a height of ~1.5 km over the crater. Ash drifted SSE and accumulated as an up to 1-mm-thick layer in the town of Tomohon. Incandescent material was hurled to ~350 m high and cascaded around the crater. Through 0900 on 3 April tremor earthquakes continued to be recorded. Lokon-Empung remained at Alert Level 2 (on a scale of 1-4).
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.