Badan Nacional Penanggulangan Bencana (BNPB) reported that between 1200 and 1800 on 23 January pyroclastic flows traveled 1.5 km down Sinabung's S flank. The number of displaced people reached 28,715 (9,045 families) in 42 evacuation centers. Based on webcam views, satellite images, ground reports, and altitude and drift directions derived from wind data, the Darwin VAAC reported that during 22-23 and 25-27 January ash plumes rose to an altitude 5.2 km (17,000 ft) a.s.l. and drifted 35-185 km N, NE, and E.

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), Darwin Volcanic Ash Advisory Centre (VAAC)