Report on Manam (Papua New Guinea) — 5 December-11 December 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 December-11 December 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Manam (Papua New Guinea). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 December-11 December 2012. Smithsonian Institution and US Geological Survey.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
RVO reported that during 1-7 December both diffuse and dense ash plumes rose 500 m above Manam's Southern Crater and drifted NW. Ashfall was reported in areas downwind. Roaring and rumbling were heard, and became loud and frequent on 4 December. Ejected incandescent tephra was observed at night, and a small volume of lava effused from a SE valley vent that formed in August. Small volumes of lava also flowed from a vent, adjacent to the first vent, which opened in late November. White vapor plumes rose from Main Crater during the reporting period. Data from the electronic tiltmeter showed a long-term inflationary trend towards the E. RVO warned residents to stay away from the four main radial valleys, especially to the SE and SW, because products of the current activity are channeled into them.
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.
Source: Rabaul Volcano Observatory (RVO)