PVMBG reported that at 1331 on 4 April an explosion at Agung ejected incandescent material out of the crater and onto the flanks within a 2-3 km radius, mainly on the S flank. A dense gray ash plume rose 2 km above the crater rim and, based on satellite data, drifted W and S. Ashfall was reported in areas downwind including Telungbuana, Badeg, Besakih (7 km SW), Pempatan (8 km W), Teges, and Puregai. Roaring was heard at the observation post in Rendang (12 km NW). The Alert Level remained at 3 (on a scale of 1-4) with the exclusion zone set at a 4-km radius.

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), Darwin Volcanic Ash Advisory Centre (VAAC)