Report on Manam (Papua New Guinea) — 26 September-2 October 2018
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 September-2 October 2018
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2018. Report on Manam (Papua New Guinea). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 26 September-2 October 2018. 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 pale-gray-to-brown ash plumes rose from Manam’s Southern Crater during 20 September-1 October. Activity was most intense on 24 September, with an increased amount of ash emissions, and occasional weak roaring and rumbling noises. Based on seismic data an eruption at Main Crater began during 0100-0130 on 1 October, peaked around 0200, and ended at 1200 (though a sharp decline was recorded at 1215). Ash plumes rose at least several hundred meters above the crater rim, though darkness obscured visual observations. Islanders described loud roaring and rumbling noises, as well as loud banging noises. Residents of Tabele on the SW side of the island observed bright summit incandescence, which was also visible from the Bogia Government Station on the mainland (22 km SSW). Scoria and minor amounts of ash fell in Jogari and villages to the N.
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)