On 5 June BNPB reported that the Alert-Level increase for Sinabung on 2 June prompted 2,727 people (677 families) from the S and SE flanks to evacuate. PVMBG reported that foggy weather often prevented visual observations during 5-10 June, except for a few clearer periods on some days. White plumes rose at most 1 km above the crater, and lava flows on the flanks were incandescent as far as 2 km S and SE. Pyroclastic flows traveled 0.7-1.3 km daily down the S and SE flanks. Ash plumes from pyroclastic flows rose as high as 1 km during 5-6 and 10 June. The Alert Level remained at 4 (on a scale of 1-4).

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), Badan Nacional Penanggulangan Bencana (BNPB)