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Report on Lewotobi (Indonesia) — June 1991


Lewotobi

Bulletin of the Global Volcanism Network, vol. 16, no. 6 (June 1991)
Managing Editor: Lindsay McClelland.

Lewotobi (Indonesia) Strombolian activity; ash to 300 m height; several hundred explosion earthquakes weekly

Please cite this report as:

Global Volcanism Program, 1991. Report on Lewotobi (Indonesia) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199106-264180



Lewotobi

Indonesia

8.542°S, 122.775°E; summit elev. 1703 m

All times are local (unless otherwise noted)


Explosions at the summit crater on 28 May at 1615, 1840, and 1911 produced ash clouds to 300 m, accompanied by thunder-like sounds heard 4 km SW of the crater (at Pos Observatory). Since then, activity has been dominated by gas emissions and explosion earthquakes (figure 1). Explosions emitted ash (12-19 times/week) to 100-300 m high. On 8 and 13 June, lapilli and bombs ejected by Strombolian activity covered the area surrounding the crater. Glow and lava fountaining then steadily diminished through the end of June. Explosion earthquakes were recorded 200-405 times/week, compared to 0-4 deep and shallow volcanic earthquakes, and 5-7 tectonic earthquakes/week. No tremor episodes were recorded.

Figure (see Caption) Figure 1. Daily number of earthquakes and explosion events at Lewotobi Lakilaki, May 1991. Arrows represent explosions. Courtesy of VSI.

Geological Summary. The Lewotobi edifice in eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (the "husband and wife"). Their summits are less than 2 km apart along a NW-SE line. The conical Laki-laki to the NW has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the E flank of Perampuan.

Information Contacts: W. Modjo, VSI.