Report on Manam (Papua New Guinea) — May 1998
Bulletin of the Global Volcanism Network, vol. 23, no. 5 (May 1998)
Managing Editor: Richard Wunderman.
Manam (Papua New Guinea) Short-lived Vulcanian episode unsettles month of mild activity
Please cite this report as:
Global Volcanism Program, 1998. Report on Manam (Papua New Guinea). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 23:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199805-251020.
Papua New Guinea
4.08°S, 145.037°E; summit elev. 1807 m
All times are local (unless otherwise noted)
Mild activity from Manam's two summit craters continued throughout May. Emissions at both Southern and Main craters chiefly consisted of white vapors released at weak to moderately high rates.
An hour-long Vulcanian episode occurred on 21 May. At 1300 a single large explosion at Southern crater produced a gray-brown ash cloud that rose ~ 500 m above the crater, followed by occasional gray ash emissions at 3-5 minute intervals. The ash clouds drifted to the SE of the island leaving a fine ashfall in its wake. There was no visible glow at night.
Seismicity remained at low levels. From 1,100 to 1,400 low-frequency events of very low amplitudes were recorded daily. The water-tube tiltmeter at Tabele Observatory, 4 km SW of the summit, showed an inflation of 2 µrad prior to the Vulcanian phase of 21 May, which remained to the end the month.
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: Ben Talai and H. Patia, RVO.