Report on Lokon-Empung (Indonesia) — 20 July-26 July 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
20 July-26 July 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Lokon-Empung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 July-26 July 2011. Smithsonian Institution and US Geological Survey.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
CVGHM reported that during 20-21 July seismicity and visual observations of Tompaluan crater, in the saddle between the Lokon-Empung peaks, indicated that activity continued to be high. On 20 July plumes rose 100-500 m above the crater, and during 21-24 July white plumes rose 100-300 m above the crater. CVGHM noted that, since the eruption on 18 July, most data showed a decline in activity and therefore on 24 July the Alert Level was lowered to 3 (on a scale of 1-4). Residents and tourists were not permitted within a 3-km radius of the crater. A news article stated that on that same day about 5,000 residents that had evacuated returned home, and about 200 people remained in shelters.
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.