PVMBG reported that during 4-14 January inclement weather sometimes prevented visual observations of Sinabung and the growing lava dome in the summit crater. As many as 192 hot avalanches and 12 pyroclastic flows traveled 0.5-3 km ESE. Ash plumes from a total of 40 events rose as high as 3 km. 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 in the SSE sector, and within 6 km in the ESE sector, should evacuate.

Based on information from PVMBG and satellite images, the Darwin VAAC reported that during 13-15 and 17-19 January ash plumes from Sinabung rose to altitudes of 3-4.3 km (10,000-14,000 ft) a.s.l. and drifted NW, W, and SW.

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.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)