"During March, Manam's summit was often obscured by clouds, but when visible, both vents were usually emitting white vapours. Weak rumbling noises were heard on the E side of the volcano on 7 March. Activity strengthened in April, when glow and lava ejections from Southern crater were commonly seen. The highest ejections rose to about 50-60 m above the summit. No eruptions of ash were seen, but white and blue vapours were emitted. A blue haze was occasionally seen in the upper parts of some of the major valleys that descend from the summit. Main crater was usually obscured, but white emissions were observed on a few days. Seismic activity remained at its usual level and tilt readings indicated no trends."

Geological Summary. The 10-km-wide island of Manam, lying 13 km off the northern coast of mainland Papua New Guinea, is one of the country's most active volcanoes. Four large radial valleys extend from the unvegetated summit of the conical basaltic-andesitic stratovolcano to its lower flanks. These valleys channel lava flows and pyroclastic avalanches that have sometimes reached the coast. Five small satellitic centers are located near the island's shoreline on the northern, southern, and western sides. Two summit craters are present; both are active, although most observed eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent eruptions, typically of mild-to-moderate scale, have been recorded since 1616. Occasional larger eruptions have produced pyroclastic flows and lava flows that reached flat-lying coastal areas and entered the sea, sometimes impacting populated areas.

Information Contacts: C. McKee, RVO. [Information Contacts for this and following RVO reports were corrected by the RVO staff in January 1988.]