Report on Lokon-Empung (Indonesia) — December 2002
Bulletin of the Global Volcanism Network, vol. 27, no. 12 (December 2002)
Managing Editor: Richard Wunderman.
Lokon-Empung (Indonesia) Higher-than-normal activity continues through at least December 2002
Please cite this report as:
Global Volcanism Program, 2002. Report on Lokon-Empung (Indonesia). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 27:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN200212-266100.
1.358°N, 124.792°E; summit elev. 1580 m
All times are local (unless otherwise noted)
Higher-than-normal activity continued at Lokon-Empung during August-December 2002. Throughout the report period a "white-thin ash plume" rose 25-75 m above the crater rim. No ashfall was reported. Seismicity was dominated by shallow volcanic and tectonic earthquakes (table 4).
|Date||Deep volcanic (A-type)||Shallow volcanic (B-type)||Tectonic|
|05 Aug-11 Aug 2002||19||42||32|
|12 Aug-18 Aug 2002||9||11||35|
|19 Aug-25 Aug 2002||14||51||42|
|26 Aug-01 Sep 2002||19||53||28|
|02 Sep-08 Sep 2002||14||39||32|
|09 Sep-15 Sep 2002||18||50||33|
|16 Sep-22 Sep 2002||16||37||39|
|23 Sep-29 Sep 2002||2||18||46|
|30 Sep-06 Oct 2002||9||17||39|
|07 Oct-13 Oct 2002||5||7||35|
|14 Oct-20 Oct 2002||5||4||29|
|21 Oct-27 Oct 2002||6||25||44|
|28 Oct-03 Nov 2002||0||1||35|
|04 Nov-10 Nov 2002||1||4||26|
|23 Dec-29 Dec 2002||29||74||31|
During the week of 4-10 November, the hazard status was reduced from Alert Level 2 to 1 (on a scale of 1-4). On 23 December a "white-thick ash plume" rose 100-250 m over Tompaluan crater. No ashfall was reported. [A later report did note ashfall.] The same day, volcanic tremor with an amplitude of 0.5-2 mm occurred. A total of 42 emissions were reported during 23-29 December. The Alert Level returned to 2 by the end of the report period.
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.
Information Contacts: Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).