Report on Manam (Papua New Guinea) — 29 July-4 August 2020
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 29 July-4 August 2020
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2020. Report on Manam (Papua New Guinea) (Sennert, S, ed.). Weekly Volcanic Activity Report, 29 July-4 August 2020. 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 seismicity at Manam began increasing on 16 July and fluctuated between low and moderate levels through the 29th. A slow steady increase of RSAM values was recorded on 30 July, and RVO stated that an observer had reported that incandescent material had been ejected from the summit. The Darwin VAAC noted that a sustained and intense thermal anomaly was visible in satellite images that same day. During 31 July-1 August ash plumes drifted NW at an altitude of 4.3 (14,000 ft) a.s.l. and a lava flow at the summit was visible.
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.