Report on Sinabung (Indonesia) — 30 October-5 November 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 October-5 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, 30 October-5 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)
An eruption began at 0126 on 3 November that generated ash plumes up to 7 km a.s.l. (~23,000 ft) and triggered evacuations from communities within 3 km of the volcano (approximately 1,681 residents); the ash plume drifted W. Rumbling sounds that lasted up to 10 minutes long were noted by staff at the Sinabung Observation Post (~8.5 km from the volcano). News agencies reported that this was the second largest eruption since the 24 October event that displaced more than 3,300 people.
The Alert Level was increased from Level II (Watch) to Level III (Alert) at 0300. A second eruption occurred in the afternoon. PVMBG reported that Sinabung had been erupting more frequently and with increasing energy.
PVMBG reported that elevated seismicity, including events of continuous tremor, was ongoing since 29 October. Relatively small ash explosions were also reported prior to the larger events on 3 November. During 29 October-2 November plumes rose to 200-2,000 m above the summit. Gas measurements conducted during 31 October and 1-2 November showed an SO2 flux of 226-426 tons per day; this was a general decrease in emissions. During 31 October ashfall was noted on the SE flank up to 1 km from the summit.
PVMBG reported that an eruption occurred at 1423 on 5 November. This event lasted for 20 minutes and generated an ash plume up to 3,000 m above the crater that drifted SW. Rumbling sounds were also noted by staff at the observation post. Pyroclastic flows were observed at 1431; the flows extended 1 km down the SE flank. No casualties were reported due to the event. The evacuated residents remained displaced on 5 November.
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.