Report on Dempo (Indonesia) — 31 December-6 January 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 December-6 January 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2008. Report on Dempo (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 31 December-6 January 2009. Smithsonian Institution and US Geological Survey.
4.016°S, 103.121°E; summit elev. 3142 m
All times are local (unless otherwise noted)
CVGHM reported that on 1 January, a phreatic eruption from Dempo resulted in a strong sulfur odor and "ash rain" that was noted as far as about 10 km from the summit. Fog prevented direct observations of the summit. The Alert Level was raised to 2 (on a scale from 1-4). Visitors and residents were advised not to go within a 2-km radius of the summit.
Geologic Background. Dempo is a prominent stratovolcano that rises above the Pasumah Plain of SE Sumatra. The andesitic volcanic complex has two main peaks, Gunung Dempo and Gunung Marapi, constructed near the SE rim of a 3 x 5 km caldera breached to the north. The Dempo peak is slightly lower, and lies at the SE end of the summit complex. The taller Marapi cone was constructed within a crater cutting the older Gunung Dempo edifice. Remnants of seven craters are found at or near the summit, with volcanism migrating WNW over time. The large, 800 x 1100 m wide historically active crater cuts the NW side of the Marapi cone and contains a 400-m-wide lake located at the far NW end of the crater complex. Historical eruptions have been restricted to small-to-moderate explosive activity that produced ashfall near the volcano.