During 18-19 July BNPB reported that Sinabung remained active; pyroclastic flows traveled 2.5-3 km E and SE, ash plumes rose as high as 1 km, and lava was active as far as 1.5 km SE. Seismicity was high and the lava dome continued to extrude. A total of 11,111 people (3,150 families) remained displaced. The Alert Level remained at 4 (on a scale of 1-4). Based on satellite images, weather models, and information from PVMBG, the Darwin VAAC reported that during 18-20 July explosions generated ash plumes that rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted E. White plumes rose 200 m on 21 July.

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: Darwin Volcanic Ash Advisory Centre (VAAC), Badan Nacional Penanggulangan Bencana (BNPB)