Report on Sinabung (Indonesia) — 24 February-2 March 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
24 February-2 March 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Sinabung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 24 February-2 March 2021. Smithsonian Institution and US Geological Survey.
3.17°N, 98.392°E; summit elev. 2460 m
All times are local (unless otherwise noted)
PVMBG reported that the eruption at Sinabung continued during 24 February-2 March. White plumes rose as high as 500 m above the summit most days. On 25 February avalanches of material traveled 500-1,000 m down the E, SE, and S flanks. The Darwin VAAC noted that an ash plume rose to 4 km (13,000 ft) a.s.l., or 1.5 km above the summit, and drifted SE, based on satellite images and information from PVMBG. On 28 February avalanches of material traveled 1,000-1,250 m down the E, SE, and S flanks; the VAAC noted that ash plumes were visible in satellite images and rose to 3.4 km (11,000 ft) a.s.l. (about 1 km above the summit) and drifted SW. On 1 March avalanches of material descended the E, SE, and S flanks as far as 1.3 km.
A series of lava-dome collapses began at 0642 on 2 March. A total of 13 pyroclastic flows, each lasting between about two and eight minutes, traveled 2-5 km SE and E. Ash plumes rose 4-5 km along the length of the pyroclastic flows and drifted W, SW, S, and E. The VAAC reported that ash plumes were visible in satellite images beginning at 0640 rising to 4.3 km (14,000 ft) a.s.l. and drifting SW. Ash plumes rose to 7.6 km (25,000 ft) a.s.l. and drifted W by 0758; within another 25 minutes the plumes had risen to 12.2 km (40,000 ft) a.s.l. According to BNPB ashfall was noted in 17 villages in the Tiganderket District, eight villages in the Kutabuluh District, and 15 villages in the Tigabinaga District. The Alert Level remained at 3 (on a scale of 1-4), with a general exclusion zone of 3 km and extensions to 5 km in the SE sector and 4 km in the NE sector.
Geological Summary. Gunung Sinabung is a Pleistocene-to-Holocene stratovolcano with many lava flows on its flanks. The migration of summit vents along a N-S line gives the summit crater complex an elongated form. The youngest crater of this conical andesitic-to-dacitic edifice is at the southern end of the four overlapping summit craters. The youngest deposit is a SE-flank pyroclastic flow 14C dated by Hendrasto et al. (2012) at 740-880 CE. An unconfirmed eruption was noted in 1881, and solfataric activity was seen at the summit and upper flanks in 1912. No confirmed historical eruptions were recorded prior to explosive eruptions during August-September 2010 that produced ash plumes to 5 km above the summit.