RVO reported that activity at Manam's Southern and Main craters remained low during 22-31 July; observers noted white vapor plumes rising from the craters during periods of clear weather. Considerable amounts of blue vapor rose from Southern Crater during 25-26 July. Deep and low booming noises were heard on the island on most days since 24 July, however, on 30 July a loud explosion was heard in Bogia, 25-30 km SSW of Manam on the N coast of the mainland. Seismicity fluctuated but remained high.

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)