"April activity was steady with moderate to strong emissions of white vapours from the summit area, and a small number (up to ~15) of seismic events/day. During an aerial inspection on the 26th, the emission plume was dense and white in colour, and rose ~1.2 km above [the] summit. Its length was ~5-10 km.

"The nose of the active lava flow on the E flank had advanced ~50-100 m since the last inspection in late February. It had also widened as it spread out on the more gentle lower slopes of the cone. The flow appeared to be as much as 50 m thick in places and there were occasional slides of unstable material from the edges. The September 1987 pyroclastic avalanche deposit at the E base of the cone was also inspected. Many of the rootless fumaroles were still steaming. The craters and sulphur deposits around many of these fumaroles have been preserved."

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: D. Lolok, C. McKee, and B. Talai, RVO.