CVGHM reported that on 28 August Sinabung emitted diffuse white plumes that rose 20 m and showed no signs of increased activity. On 29 August rumbling was heard, prompting authorities to contact and move people living within a 6-km-radius of the volcano. Later that day, an explosion produced an ash plume that rose 1.5 km above the crater, and the Alert Level was raised to 4 (on a scale of 1-4). Media footage of the eruption at one point showed two closely spaced ash plumes from vents near the summit; the ash plumes caused domestic flights to be diverted. The next day a second, more powerful, explosion generated an ash plume that rose 2 km above the crater. The number of people media sources reported had evacuated ranged from 20,000 to 30,000. Ash fell in nearby areas and a strong sulfur odor was reported. Nighttime video showed incandescent material descending the flank of the volcano.

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), Daily Mail, Associated Press