PVMBG reported that white-and-gray plumes rose 100-300 m above Sinabung during 20-21 July and drifted N, NE, E, and SE. During 21-27 July white plumes rose as high as 400 m and drifted NE, E, and SE. At 1320 on 28 July an eruption produced an ash plume that rose 4.5 km above the summit and drifted E and S; the event lasted for about 12 and a half minutes. The Aviation Color Code was raised to Red. The Alert Level remained at 2 (on a scale of 1-4), and the public was warned to remain outside of the 2-km exclusion zone.

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)