PVMBG reported that at 1320 on 28 July an eruption at Sinabung produced dense ash plumes that rose as high as 4.5 km above the summit that drifted E and S; pyroclastic flows traveled as far as 1 km down the E and SE flanks. The event lasted over 12 minutes, and caused ashfall in areas to the E including the subdistricts of Namanteran, Merdeka, Berastagi, and Simpang Empat. White plumes rose up to 500 m above the summit during 29 July-2 August; weather conditions sometimes prevented visual observations. 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)