PVMBG reported that the eruption at Sinabung continued during 4-11 May. Weather conditions sometimes prevented visual observations of the volcano, though white fumarolic plumes were visible almost daily rising as high as 500 m above the summit and drifting in multiple directions. Daily avalanches descended 500-1,500 m down the E and SE flanks. At 1119 on 6 May an ash plume rose 2 km above the summit and drifted E. At 0908 and 1519 on 7 May ash plumes rose 3 km and drifted E. Ash plumes rose 1-2.8 km and drifted E, WNW, and W at 1044, 1656, and 1841 on 8 May; plumes were also seen on 9 May. At 0747 on 10 May an ash plume rose 2.5 km and drifted SW. Ash plumes on 11 May rose 700 m and drifted W at 0712, and rose 1.5 km and drifted E at 1428. 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 in 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)