Report on Lokon-Empung (Indonesia) — 26 March-1 April 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
26 March-1 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, 26 March-1 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)
VSI decreased the Alert Level at Lokon-Empung on 24 March from 3 to 2 (on a scale of 1-4) due to a decrease in volcanic activity. During 17-23 March, "white-thick ash emissions" rose to ~300 m above Tompaluan crater, ash explosions occurred, and there was a significant decrease in emission earthquakes compared to the previous week. On 27 March at 0156 an explosion ejected ash to 1.5 km and incandescent volcanic material to 400 m above the crater. An ash cloud drifted S and ash fell around the summit. Ash was not visible on satellite imagery. Lokon-Empung remained at Alert Level 2.
Geological Summary. The Lokong-Empung volcanic complex, rising above the plain of Tondano in North Sulawesi, includes four peaks and an active crater. Lokon, the highest peak, has a flat craterless top. The morphologically younger Empung cone 2 km NE has a 400-m-wide, 150-m-deep crater that erupted last in the 18th century. A ridge extending 3 km WNW from Lokon includes the Tatawiran and Tetempangan peaks. All eruptions since 1829 have originated from Tompaluan, a 150 x 250 m crater in the saddle between Lokon and Empung. These eruptions have primarily produced small-to-moderate ash plumes that sometimes damaged croplands and houses, but lava-dome growth and pyroclastic flows have also occurred.