Following the 4 June 2000 eruption at Southern Crater (BGVN 25:07), volcanic activity was low at both summit craters through October 2000. Seismicity remained relatively stable except for a slight increase in amplitudes beginning on 18 September.

During August, activity at the two summit craters was low. Main Crater gently emitted small-to-moderate volumes of white vapor, while Southern Crater weakly emitted white vapor. Seismic-event amplitudes steadily increased throughout the month, though the overall trend remained within background levels. Daily average event counts were about 1,200, with some fluctuations. No significant movements were recorded by the water-tube tiltmeter 4 km SW of the summit.

Activity remained low throughout September, with vapor emissions from both craters similar to those in August. Seismic amplitudes were steady until 18 September when a slight increase was observed that continued through the end of the month. Daily average seismic event counts remained steady, with about 1,300 events/day.

Throughout October both craters emitted varying amounts of white vapor, and there were no reports of noise or night glow. Seismicity and tilt measurements appeared to remain at background levels, although consistent measurements could not be made because scientists did not have access to the Tabele Observatory during 5-21 October.

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, David Lolok, Herman Patia, and Steve Saunders, Rabaul Volcano Observatory (RVO), P.O. Box 386, Rabaul, Papua New Guinea.