During 6-12 August, DMPGM reported increasing volcanic activity at Bagana volcano. Thin to thick white vapor plumes from Bagana were accompanied on 6, 8 August by reports of rockfalls. On 10 August an ash plume rose to an estimated several hundred meters above the crater drifting SW and W. Moderate ash was reported in Wakovi (6 km W) and decreased downwind. Residents were advised to evacuate to Gotana (9 km SW) if ashfall continued. On 11 August the Darwin VAAC reported ash plumes rose to 3 km (10,000 ft) a.s.l. and drifted up to 55 km SW. On 12 August Darwin VAAC raised the Aviation Color Code to Red as ash plumes rose to 7.6 km (25,000 ft) a.s.l. and drifted up to 167 km SW.

Geological Summary. Bagana volcano, in a remote portion of central Bougainville Island, is frequently active. This massive symmetrical cone was largely constructed by an accumulation of viscous andesitic lava flows. The entire edifice could have been constructed in about 300 years at its present rate of lava production. Eruptive activity is characterized by non-explosive effusion of viscous lava that maintains a small lava dome in the summit crater, although occasional explosive activity produces pyroclastic flows. Lava flows with tongue-shaped lobes up to 50 m thick and prominent levees descend the flanks on all sides.

Sources: Darwin Volcanic Ash Advisory Centre (VAAC), Department of Mineral Policy and Geohazards Management (DMPGM)