Report on Sinabung (Indonesia) — 20 November-26 November 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 November-26 November 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Sinabung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 20 November-26 November 2013. 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 three explosions from Sinabung on 17 November. The first explosion, at 2024, generated an ash plume that rose 500 m and drifted SW, and a pyroclastic flow that traveled 500 m down the SE flank. At 2152 a dense ash plume from an explosion rose 500 m and drifted SW. Incandescent material was ejected 50 m away from the crater. At 2252 an ash plume rose 1 km and drifted SW. At 0704 on 18 November an explosion generated an ash plume that rose 8 km and drifted SW. A pyroclastic flow also traveled 800 m down the SE flank.
On 19 November at 2155 a dense ash plume rose 10 km, drifted SW, and exhibited lightning. Pyroclastic flows again traveled 500 m SE. Multiple explosions on 20 November (at 0240, 0405, 0529, 0619, and 0641) generated ash plumes that rose to heights between 1 and 3.5 km. An explosion at 1716 was detected by the seismic network but cloud cover prevented observations of possible plumes. White plumes rose 100 m on 21 and 23 November; misty conditions prevented visual observations on 22 November. On 23 November scoria fell in the Sigarang-garang and Desa Kuta villages in the NNE. Two explosions on 24 November, at 0043 and 0232, were detected but not visually observed. Ash plumes rose 8 km and drifted NNE at 0727, rose 1 km at 0812, and rose 3 km at 0855. Since Sinabung's activity continued to increase, PVMBG raised the Alert Level to 4 (on a scale of 1-4) on 24 November. PVMBG noted that residents and tourists were not to approach the crater within a 5-km radius, and that remaining residents in 17 villages around the volcano were to be evacuated. On 25 November Badan Nacional Penanggulangan Bencana (BNPB) reported that 17,713 people, out of the 20,270 residents living within 5 km, had been evacuated to 31 shelters.
Geologic Background. 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.