Report on Manam (Papua New Guinea) — December 1990
Bulletin of the Global Volcanism Network, vol. 15, no. 12 (December 1990)
Managing Editor: Lindsay McClelland.
Manam (Papua New Guinea) Vapor emission; weak seismicity
Please cite this report as:
Global Volcanism Program, 1990. Report on Manam (Papua New Guinea) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 15:12. Smithsonian Institution.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
"Activity was at a very low level in December. Both craters released very weak and occasionally moderate emissions of mostly thin white vapour. No night glows or sounds were reported from the two craters. Seismicity remained at a very low level and no significant changes were observed in measurements from the water-tube tiltmeters.
"An aerial inspection and ground deformation surveys were conducted 7-9 November. There have been no morphological changes at the summit since the last aerial inspection (July 1989). EDM measurements indicated little change along lines radial to the summit between November 1987 and November 1990. Dry tilt results were inconsistent, with two stations showing components of inflation while the third station indicated a component of deflation."
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: B. Talai, RVO.