Report on Dempo (Indonesia) — 16 August-22 August 2023
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 16 August-22 August 2023
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2023. Report on Dempo (Indonesia) (Sennert, S, ed.). Weekly Volcanic Activity Report, 16 August-22 August 2023. Smithsonian Institution and US Geological Survey.
4.016°S, 103.121°E; summit elev. 3142 m
All times are local (unless otherwise noted)
PVMBG reported that an eruption at Dempo occurred at 2105 on 21 August, but no ash emissions were observed. A video posted on social media showed a Surtseyan eruption through the crater lake, with steam plumes and dark material being ejected above the lake. The Aviation Color Code was raised to Orange (the third color on a four-color scale). The Alert Level remained at 2 (on a scale of 1-4), and the public were reminded to stay 1 km away from the crater and as far as 2 km on the N flank.
Geological Summary. Dempo is a stratovolcano that rises above the Pasumah Plain of SE Sumatra. The andesitic complex has two main peaks, Gunung Dempo and Gunung Marapi, constructed near the SE rim of a 3-km-wide amphitheater open to the north. The high point of the older Gunung Dempo crater rim is slightly lower, and lies at the SE end of the summit complex. The taller Marapi cone was constructed within the older crater. Remnants of seven craters are found at or near the summit, with volcanism migrating WNW over time. The active 750 x 1,100 m active crater cuts the NW side of the Marapi cone and contains a 400-m-wide lake at the far NW end. Eruptions recorded since 1817 have been small-to-moderate explosions that produced local ashfall.