Report on Sinabung (Indonesia) — 24 June-30 June 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 June-30 June 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Sinabung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 24 June-30 June 2015. Smithsonian Institution and US Geological Survey.
3.17°N, 98.392°E; summit elev. 2460 m
All times are local (unless otherwise noted)
PVMBG reported that foggy weather sometimes prevented visual observations of Sinabung during 22-29 June. White plumes rose as high as 500 m above the crater, and lava flows on the flanks were incandescent as far as 3 km S and SE. Multiple pyroclastic flows per day during 22-26 and 28 June traveled 2.5-4 km down the flanks from the SSE to the SE. One pyroclastic flow was observed on 27 June. Ash plumes rose generally 3.5 km on most days, drifting E, SE, and S, although an ash plume rose as high as 5 km on 25 June. Seismicity consisted of avalanche signals, low-frequency and hybrid events, tremor, tectonic events, and volcanic earthquakes; RSAM values increased due to an increase of avalanche signals. Deformation data showed a trend of inflation. The Alert Level remained at 4 (on a scale of 1-4), indicating that people within 7 km of the volcano on the SSE sector, and within 6 km in the ESE sector, should evacuate.
Geologic Background. 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.