Report on Lokon-Empung (Indonesia) — 21 March-27 March 2001
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 March-27 March 2001
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2001. Report on Lokon-Empung (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 21 March-27 March 2001. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
Activity continued after the 28 January 2001 explosion. On 26 March 2001 at 1440 another eruption sent a dark ash plume 1,500 m above the crater rim. Ash drifted E and N. No incandescent material was observed, but 25 minutes after the explosion ash started to fall at Kinilow village (3.5 km from the crater) and Kakaskasen village (4 km from the crater). Activity slowly decreased though 1510, when thick white gas emissions from the crater rose 400 m. The ashfall was 0.3-0.5 cm thick at Kinilow village, 0.1-0.3 cm thick at Kakaskasen village, and 1-2 cm thick around Pasahapen river, about 1 km from the crater. After the initial explosion, volcanic tremor was recorded between 1442 and 1457 with a maximum amplitude of 2-16 mm. The seismograph recorded 13 deep volcanic (type A) and 12 shallow volcanic (type B) events on 25 March; six deep and seven shallow volcanic earthquakes were detected on the 26th.
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.