Report on Agung (Indonesia) — 7 February-13 February 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 February-13 February 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Agung (Indonesia). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 7 February-13 February 2018. Smithsonian Institution and US Geological Survey.
8.343°S, 115.508°E; summit elev. 2997 m
All times are local (unless otherwise noted)
On 10 February PVMBG reported that activity at Agung had declined during the previous month or two leading the observatory to lower the Alert Level to 3 (on a scale of 1-4) and adjusted the exclusion zone to a 4-km radius. The report noted that the tallest eruption plume in January was 2.5 km above the crater rim, occurring on 19 January, and the last event on 24 January generated a plume that rose 1 km. The volume of erupted lava was an estimated 20 million cubic meters in December 2017, and had not significantly changed. Seismicity continued to fluctuate, though the number and magnitude of events had declined. Satellite data showed a decrease in thermal output reflective of a reduced lava flow rate. PVMBG warned that activity at Agung is still high and unstable; tiltmeter data showed low rates of inflation (GPS patterns were stable) and gas-emission data indicated magma movement at depth, though at a lower intensity compared to values measured at the end of November 2017. An event at 1149 on 13 February generated as ash plume that rose 1.5 km above the crater rim.
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.