PVMBG reported that an eruption at Sinabung was recorded at 0253 on 25 May. An ash plume from the event drifted W and NW according to the Darwin VAAC; fog prevented ground-based visual observations. Ashfall was reported in several areas downwind according to a news article. At 0629 on 27 May a dense gray ash plume rose 2.5 km above the crater rim and drifted S. The VAAC reported that at 0700 an ash plume was visible in satellite images at an altitude of 6.1 km (20,000 ft) a.s.l., or 3.7 km above the crater rim. Eruptive events were recorded at 2323 on 27 May and 0118 on 28 May, though ash plumes were not visible. 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 on 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.

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