PVMBG reported that during 20-26 December gray-and-white plumes rose as high as 2 km above Agung’s crater rim and drifted W and E; weather clouds and fog sometimes prevented visual observations. Incandescence from the crater was sometimes observed at night. BNPB reported that during 22-23 December events generated dense gray ash plumes that rose as high as 2.5 km above the crater rim and drifted NE. Ash fell on the flanks and in Tulamben, Kubu. As of 25 December there were 71,045 evacuees spread out in 239 shelters. The Alert Level remained at 4 (on a scale of 1-4), and the exclusion zones continued at a general 8-km radius and 10 km in the NNE, SE, S, and SW directions.

Geological Summary. 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 rim of the Batur caldera, 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.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Badan Nacional Penanggulangan Bencana (BNPB)