The summit area of Manam was obscured by rain and atmospheric clouds on most days during January-March 2003, making it difficult to observe emissions from the two summit craters. When clear, the Main Crater released small-to-moderate volumes of thin white vapor. Southern Crater generally released small-volume white emissions. Seismicity was low. Small low-frequency earthquakes were recorded on most days. Slightly greater numbers of earthquakes occurred on 16, 17, 23, 25, and 27 January. Some volcano-tectonic earthquakes were recorded on 11 (1), 12 (1), and 16 January (3); the events on the 16th were larger than the others. No volcano-tectonic earthquakes were recorded in February, and there was no seismic recording during March.

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.