Low-level activity persisted during May as in previous months (BGVN 21:04). Both summit craters emitted white vapor in variable quantity. Blue vapor from South Crater was seen on 28 and 29 May, and weak roaring noises were heard on the evening of 6 May. Between 1 and 5 May the daily occurrence of low-frequency earthquakes ranged from 440 to 690 events/day. This value increased up to 800-1,690 events/day during 6-30 May. On the 31st the seismicity dropped to the early May level.

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: D. Lolok and C. McKee, RVO.