RVO reported that activity at both Manam's Southern Crater and Main Crater was low during 1-18 March although inclement weather made crater observations difficult; no noises were reported. Seismicity had slowly and erratically increased since 28 February, peaked on 13 March and remained at that level through 15 March, and then increased again through 18 March. The seismicity was characterized by small-to-moderate, sub-continuous, and continuous volcanic tremor. Discrete low-frequency earthquakes were also recorded.

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.

Source: Rabaul Volcano Observatory (RVO)