Report on Lokon-Empung (Indonesia) — 5 March-11 March 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 March-11 March 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, 5 March-11 March 2003. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
Explosive activity continued at Lokon-Empung during 24 February to 2 March, with 12 explosions producing "white-gray ash columns" that rose 300 m above the volcano. An explosion on 2 March at 2129 was preceded by 204 shallow and 77 deep volcanic earthquakes. During the explosion a "gray-dark ash column" rose 1.5 km above the crater, but incandescent volcanic material remained within the crater. Ash drifted about 14.5 km from the crater to the Tondano area, depositing ~1 mm of ash. Tremor was recorded after the eruption. Lokon-Empung remained at Alert Level 3 (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.