Report on Manam (Papua New Guinea) — August 1996
Bulletin of the Global Volcanism Network, vol. 21, no. 8 (August 1996)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Weak emissions and seismic quiet
Please cite this report as:
Global Volcanism Program, 1996. Report on Manam (Papua New Guinea). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 21:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199608-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Low-level activity persisted in August. Both summit craters usually released white vapor in small amounts. Blue vapor was emitted from South Crater on a few days at the end of the month. Small, discrete explosions took place at South Crater on the 9th (1 event) and 13th (2 events).
During August seismic activity was low. Daily totals of low frequency earthquakes had a range of 200 to 1,280. Periods of tremor were recorded between the 6th and 11th. There was no visible activity associated with the tremor. Seismic amplitudes increased in the week before the seismograph became unoperational on the 27th. The water-tube tiltmeters (4.5 km SW of the summit) did not show any significant changes.
Geologic Background. 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 1807-m-high basaltic-andesitic stratovolcano to its lower flanks. These "avalanche 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 historical eruptions have originated from the southern crater, concentrating eruptive products during much of the past century into the SE valley. Frequent historical 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: C. McKee and B. Talai RVO.