Although activity at Manam remained low in April, throughout the month both Main and Southern Craters infrequently discharged white vapor. Southern Crater discharged wispy blue vapor on the 11th; faint rumbling sounds were heard on one occasion only (at 2330 on 23 April); weak night glow was seen mainly during the 2nd and 4th weeks of April, when then summit was clearly visible. Main Crater issued occasional, thin to thick white vapors. These emissions were gentle and were not accompanied by night glow or audible sounds. The seismicity fluctuated at a low level throughout the month. No significant change was shown by the water-tube tiltmeter located about 4 km SW from the summit.

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: David Lolok and Ben Talai, RVO.