Report on Sinabung (Indonesia) — 25 December-31 December 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 December-31 December 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, 25 December-31 December 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 that seismicity at Sinabung increased during 21-26 December and indicated rising magma and lava-dome growth. Observers in Ndokum Siroga, about 8.5 km away, noted dense white plumes rising 70-1,200 m above the crater. Roaring was also periodically heard. A lava dome in the North Crater, visible on 24 December, was 56 m high and 210 m wide. During 25-26 December plumes were white and gray, and rose 300-400 m above the crater. On 26 December the lava-dome volume was estimated to be over 1 million cubic meters, with a growth rate of 3.5 cubic meters per second. The Alert Level remained at 4 (on a scale of 1-4). Visitors and tourists were prohibited from approaching the crater within a radius of 5 km.
On 30 December Badan Nacional Penanggulangan Bencana (BNPB) reported that the number of displaced people reached 19,126 (5, 979 families). They also noted that activity at Sinabung had increased. Collapsing parts of the lava dome generated block-and-ash flows as well as pyroclastic flows which traveled as far as 3.5 km down the SE flank. Explosions and pyroclastic flows generated ash plumes that rose at least 6 km above the crater.
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.