Report on Ulawun (Papua New Guinea) — 7 April-13 April 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 April-13 April 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Ulawun (Papua New Guinea). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 7 April-13 April 2004. Smithsonian Institution and US Geological Survey.
Papua New Guinea
5.05°S, 151.33°E; summit elev. 2334 m
All times are local (unless otherwise noted)
RVO reported that volcanic activity was at low levels at Ulawun during 15 March to 1 April. Only white vapor was emitted from the main summit crater and there were no emissions from the north valley vent. The overall level of seismicity was low, with only small low-frequency volcanic earthquakes recorded. Electric tiltmeter measurements showed a long-term inflationary trend. According to the Darwin VAAC, on 12 and 13 April thin ash plumes from Ulawun were visible on satellite imagery at a height of ~700 m above the volcano. The plumes extended ~75 km E and NE.
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 N coast of the island of New Britain across a low saddle NE of Bamus volcano, the South Son. The upper 1,000 m is unvegetated. A prominent E-W 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.
Sources: Darwin Volcanic Ash Advisory Centre (VAAC), Rabaul Volcano Observatory (RVO)