Report on Lewotobi (Indonesia) — June 1991
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). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 16:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199106-264180.
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 1. Daily number of earthquakes and explosion events at Lewotobi Lakilaki, May 1991. Arrows represent explosions. Courtesy of VSI.|
Geologic Background. The Lewotobi "husband and wife" twin volcano (also known as Lewetobi) in eastern Flores Island is composed of the Lewotobi Lakilaki and Lewotobi Perempuan stratovolcanoes. Their summits are less than 2 km apart along a NW-SE line. The conical Lakilaki has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has erupted only twice in historical time. Small lava domes have grown during the 20th century in both of the crescentic summit craters, which are open to the north. A prominent flank cone, Iliwokar, occurs on the E flank of Perampuan.
Information Contacts: W. Modjo, VSI.