BNPB reported intense activity at Sinabung on 2 August; between 0800 and 1200, pyroclastic flows were generated 17 times and traveled as far as 4.5 km ESE. Ash plumes rose up to 4.2 km above the crater and drifted S, causing ashfall in local areas including Perbaji (4 km SW), Sukatendel, Temberun, Perteguhen (7 km ESE), Kuta Rakyat (5 km NE), Simpang Empat (7 km SE), Tiga Pancur (6 km SSE), Selandi (5 km SSW), Payung (5 km SSW), and Kuta Gugung (5 km N). Significant ashfall was noted in Ndokum Siroga (9 km ESE), Gajah (8 km E), and Naman Teran (5 km NE). BNPB noted that there were 2,038 families (7,214 people) displaced to eight shelters, and an additional 2,863 people living in refugee camps. Based on PVMBG observations, webcam and satellite images, and wind data, the Darwin VAAC reported that during 6-7 August multiple ash plumes rose as high as 5.5 km (18,000 ft) a.s.l. and drifted ENE, E, and SE. The Alert Level remained at 4 (on a scale of 1-4), with an exclusion zone of 7 km from the volcano on the SSE sector, and 6 km in the ESE sector, and 4 km in the NNE 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: Badan Nacional Penanggulangan Bencana (BNPB), Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)