PVMBG reported that during 6-12 April white plumes rose as high as 500 m above Sinabung; misty conditions prevented observations on 13 April. Lava was incandescent as far from the lava dome as 1.5 km S and SE. The main lava flow remained 2.9 km long. After pyroclastic flows descended the flanks on 2 April, a new lava flow from the growing dome formed near the crater and traveled 170 m SSE. Seismicity consisted of avalanche signals, low-frequency and hybrid events, local and far tectonic events, and volcanic earthquakes. Overall seismicity decreased compared to 30 March-6 April. Tilt and EDM (Electronic Distance Measurement) data fluctuated but showed overall deflation. The Alert Level remained at 3 (on a scale of 1-4). Visitors and tourists were prohibited from approaching the crater within a radius of 6 km on the S, 5 km on the SE, and 3 km in other directions.

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)