Weak to moderately thick white vapor emissions from both South and Main craters prevailed at Manam throughout April. No sounds were heard and no night glow was seen. Seismicity remained low, with 1,300-1,400 low-frequency, very low-amplitude events occurring per day. Water-tube tiltmeters at the Tabele Observatory (4 km SW of the summit) showed continued deflation; it has totaled ~3 µrad since mid-December 1997.

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: Ben Talai, RVO.