Activity at Manam remained low during 10 November-14 December 2003. Occasional emissions of weak to moderate gray-brown ash clouds continued from Main Crater, at a lower level compared to late October-early November. An explosion on 11 November produced an ash plume that rose slowly to ~400 m above the summit crater, causing ashfall to the E. Occasional low rumbling and weak roaring noises were heard on 12 and 28-30 November. No night-time glow was observed during November. A forceful gas emission on 5 December sent an ash column ~500 m above Main Crater, and a steady glow was observed on the night of 10 December. Southern Crater gently released weak thin white vapor gently throughout the period. Small low-frequency volcanic earthquakes continued, with a slight increase in seismicity characterized by sub-continuous volcanic tremors after 1 December.

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: Ima Itikarai, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.