Report on Ulawun (Papua New Guinea) — October 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 10 (October 1991)
Managing Editor: Lindsay McClelland
Ulawun (Papua New Guinea) Seismicity declines without eruption
Please cite this report as:
Global Volcanism Program, 1991. Report on Ulawun (Papua New Guinea). In: McClelland, L (ed.), Bulletin of the Global Volcanism Network, 16:10. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.BGVN199110-252120.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
"A buildup of seismicity observed toward the end of September continued through the first week of October, but the volcano remained in a non-erupting state, releasing vapour in small to moderate volumes. The increased seismicity consisted of periods of frequent discrete, low-frequency earthquakes. The maximum daily number of recorded events was ~350. Despite their increase in number, there was no marked increase in amplitude. This activity waned after a week and by the end of the month was at a low level, with earthquake counts of <30/day. High-frequency volcanic earthquakes were recorded occasionally throughout October."
Geologic Background. The symmetrical basaltic-to-andesitic Ulawun stratovolcano is the highest volcano of the Bismarck arc, and one of Papua New Guinea's most frequently active. Ulawun volcano, also known as the Father, rises above the north coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1000 m of the 2334-m-high Ulawun volcano is unvegetated. A prominent E-W-trending escarpment on the south may be the result of large-scale slumping. Satellitic cones occupy the NW and eastern flanks. A steep-walled valley cuts the NW side of Ulawun volcano, and a flank lava-flow complex lies to the south of this valley. Historical eruptions date back to the beginning of the 18th century. Twentieth-century eruptions were mildly explosive until 1967, but after 1970 several larger eruptions produced lava flows and basaltic pyroclastic flows, greatly modifying the summit crater.
Information Contacts: P. de Saint-Ours and C. McKee, RVO.