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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.

Volcano Profile |  Complete Bulletin


Lokon-Empung

Indonesia

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).

Table 4. Earthquakes recorded at Lokon during 5 August-29 December 2002. No reports were issued during 11 November-22 December. Courtesy VSI.

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/).