"Activity strengthened near the end of the first week in May. Brown or grey ash emissions from Southern crater were observed on most days in May, and grey ash emissions from Main crater were also observed on several days when the vent was not obscured. Light ashfalls were experienced on the W side of the island. This ash emission often occurred with little accompanying sound. However, deep booming, rumbling, and roaring noises were occasionally heard. Orange-red glows above both vents were seen on a few days, and lava fragment ejections from Southern crater were observed on 1 and 18 May. No trends were observed in tilts, but seismic amplitudes increased by a factor of about two over normal levels at the onset of the phase of ash emission."

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.