PVMBG reported that white-and-gray plumes generally rose as high as 500 m above Sinabung’s summit during 30 December-5 January. Avalanches of material traveled 500-1,200 m down the E and SE flanks each day. Three eruptive events recorded on 4 January (at 0854, 1150, and 1412) produced dense gray ash plumes that rose 700-1,000 m above the summit and drifted N, NW, and W. Three eruptive events were detected the next day as well. The first, at 0825, generated an ash plume that rose 800 m above the summit. Ash emissions were not visible from the second and third events, recorded at 2027 and 2108. 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)