Activity remained low in April, with low to moderate rates of white vapor emissions from the summit craters. On the night of 12 April, however, an ejection of incandescent lava fragments from the South Crater was accompanied by a loud roaring noise. During the rest of the month no glows were visible. Seismic monitoring was again operative in April. During the first two weeks, totals of 100-500 low-frequency earthquakes occurred daily. There was a slight increase in seismicity during the third week of the month, up to 900 events/day, which was followed by a decrease to 600 events/day by the end of April. There were no changes in earthquake amplitudes. Tilt data from the water tube tiltmeters at Tabele observatory (4 km SW of the summit) showed an inflation of ~3 µrad during the month.

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: H. Patia, RVO.