Report on Ulawun (Papua New Guinea) — March 1988
Scientific Event Alert Network Bulletin, vol. 13, no. 3 (March 1988)
Managing Editor: Lindsay McClelland.
Ulawun (Papua New Guinea) Seismicity remains strong but no eruption
Please cite this report as:
Global Volcanism Program, 1988. Report on Ulawun (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 13:3. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198803-252120.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
Despite strong microseismicity that began in [December] 1987, Ulawun showed no visible sign of increased activity. White vapour continued to be released in weak to moderate amounts from the summit crater. Recorded seismicity showed dramatic fluctuations in number of events (300-1800/day), amplitude, and style. Records showed periods of low background seismicity interspersed with sub-continuous low-frequency (B-type) events of small to large amplitude, or periods of non-harmonic tremor lasting 1/2-2 hours. No particular pattern could be recognized, but periods of tremor occurred virtually every day, usually 1 or 2 episodes lasting up to ~2 hours, although on some days up to 12 short periods of tremor were recorded.
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. The 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 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 E flanks. A steep-walled valley cuts the NW side, 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.