RVO reported that activity at Manam decreased on 18 April and continued at low levels through 21 April. Roaring noises came from both Main and Southern craters. Both craters were incandescent, but only Southern Crater ejected incandescent tephra, which became intense during 0900-1100 on 20 April. Pale gray-to-brown plumes with a minor amounts of ash rose from both craters and drifted SE. RSAM values were about 75-150 units, but between about midnight and 0100 on 22 April they began to rise. RSAM values were 600 at 0500, and then they fluctuated between 400 and 1,400 units at least through 1400, the time of the report posting. According to a news article from 25 April the Alert Level was raised to Stage 3, and an official on the island noted that women and children have begun to be evacuated to Bogia on the mainland.

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.

Sources: Rabaul Volcano Observatory (RVO), Radio New Zealand