Report on Lokon-Empung (Indonesia) — February 2008
Bulletin of the Global Volcanism Network, vol. 33, no. 2 (February 2008)
Managing Editor: Richard Wunderman.
Lokon-Empung (Indonesia) June 2007-March 2008, variable seismicity and minor white plumes
Please cite this report as:
Global Volcanism Program, 2008. Report on Lokon-Empung (Indonesia) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 33:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200802-266100
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
Our most recent report on Lokon-Empung discussed low seismicity and plume emissions between January-October 2005 (BGVN 31:03). Since then, available reports from the Center of Volcanology and Geological Hazard Mitigation (CVGHM) discussed seismic events in June and December 2007, and January 2008. Plumes mentioned in these reports were small, white in color, and only rose 15-40 m, occasionally up to 125 m, above the rim of the active vent area (Tompaluan crater), in the saddle between the peaks of Lokon and Empung.
During 11-24 June 2007 CVGHM reported 52 A-type and 156 B-type earthquakes, but no tremor. Only one earthquake was felt by residents. The Alert Level remained at 2 (on a scale of 1-4).
On 9 December 2007, CVGHM raised the Alert Level from 2 to 3 based on visual observations, inflation detected by deformation instruments, and an increase in seismicity. The water in the Tompaluan crater changed color from green to gray and noises from degassing became stronger. Visitors were advised not to go within 2 km of the crater.
After a short period of decline, seismicity began to increase again on 22 January 2008, peaking on 3 February. Visitors were prohibited from going within 1 km of the crater.
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.
Information Contacts: Dali Ahmad, Hetty Triastuty, Nia Haerani and Suswati, Center of Volcanology and Geological Hazard Mitigation (CVGHM), Jalan Diponegoro 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).