"Observer reports indicated that the increased level of activity was continuing. Emissions were moderate to strong and consisted of white-grey (with occasional brown) ash and vapour clouds. Ashfalls around the summit area, due to rockfalls from a new lava flow on the S flank, were reported 7-11 and 25 May. Glows from the active lava flow were seen 2-3, 16-17, 22, and 24 May. Rumbling noises, correlating well with rockfalls, were heard 1-5, 12-14, and 23 May.

"Seismic monitoring . . . lapsed at the beginning of May because of an inability to maintain telemetry equipment during the current period of civil disturbance on Bougainville Island."

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.

Information Contacts: H. Patia and C. McKee, RVO.