Report on Agung (Indonesia) — 25 October-31 October 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 October-31 October 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Agung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 October-31 October 2017. Smithsonian Institution and US Geological Survey.
8.343°S, 115.508°E; summit elev. 2997 m
All times are local (unless otherwise noted)
On 29 October PVMBG lowered the Alert level for Agung to 3 (on a scale of 1-4), noting a decline in activity, especially since 20 October. The thermal anomaly in the crater identified in satellite data was less intense in October than in September. Beginning on 20 October GPS data showed a slower deformation rate. Seismic signals decreased in number and amplitude, though low-frequency events continued to indicate magma movement. White fumarolic plumes rose as high as 500 m above the crater rim during 20-29 October; a comparison of video taken by drones on 20 and 29 October showed a relative decrease in the intensity of fumarolic emissions. BNPB stated that, despite the decreased Alert Level, the exclusion zones remained intact (at 6 km, and an additional expansion to 7.5 km in the NNE, SE, S, and SW directions). The number of evacuees was 133,457 (spread out in 385 shelters).
Geologic Background. Symmetrical Agung stratovolcano, Bali's highest and most sacred mountain, towers over the eastern end of the island. The volcano, whose name means "Paramount," rises above the SE caldera rim of neighboring Batur volcano, and the northern and southern flanks extend to the coast. The summit area extends 1.5 km E-W, with the high point on the W and a steep-walled 800-m-wide crater on the E. The Pawon cone is located low on the SE flank. Only a few eruptions dating back to the early 19th century have been recorded in historical time. The 1963-64 eruption, one of the largest in the 20th century, produced voluminous ashfall along with devastating pyroclastic flows and lahars that caused extensive damage and many fatalities.