Report on Sinabung (Indonesia) — 30 December-5 January 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 30 December-5 January 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Sinabung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 30 December-5 January 2016. 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 during 21-28 December inclement weather sometimes prevented visual observations of Sinabung and the growing lava dome in the summit crater. As many as 21 hot avalanches and pyroclastic flows traveled 0.7-1.5 km ESE, producing ash plumes that rose 1 km. Ash plumes from explosions rose as high as 3 km and drifted E and SW. Seismicity consisted of avalanche and pyroclastic-flow signals, low-frequency and hybrid events, tremor, tectonic events, and volcanic earthquakes. Seismicity fluctuated at high levels, although it had declined compared to the previous week, and indicated lava-dome growth. The Alert Level remained at 4 (on a scale of 1-4), indicating that people within 7 km of the volcano on the SSE sector, and within 6 km in the ESE sector, should evacuate.
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.