Report on Ulawun (Papua New Guinea) — June 1983

Scientific Event Alert Network Bulletin, vol. 8, no. 6 (June 1983)
Managing Editor: Lindsay McClelland

Ulawun (Papua New Guinea) Five periods of volcanic tremor

Please cite this report as:

Global Volcanism Program, 1983. Report on Ulawun (Papua New Guinea). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 8:6. Smithsonian Institution. http://dx.doi.org/10.5479/si.GVP.SEAN198306-252120.

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Ulawun

Papua New Guinea

5.05°S, 151.33°E; summit elev. 2334 m

All times are local (unless otherwise noted)


"Ulawun's seismicity continued to show interesting variations, although there appears to be no correlation between the seismicity and the steady, moderate to strong white vapour emission from the summit crater.

"A number of seismic crises took place in June in which periods of volcanic tremor were recorded. The first, on 10-11 June, lasted for about 15 hours and was followed by four more: 15 June (7 hours), 16 June (7 hours), 17-18 June (17 hours), and 30 June - 2 July (48 hours). In the last, several periods of tremor were recorded. Other periods of tremor-like signals were recorded on 14, 27, and 28 June, but these were probably the effects of rainstorms on the volcano.

"Amplitudes of discrete earthquakes were generally low in June, although slightly higher amplitudes were recorded 10-18 June in relation to the first 4 periods of tremor. A brief interval of low amplitudes followed the crisis of 17-18 June, but a steady rise in amplitudes was recorded beginning 20 June.

"At times other than seismic crises, daily totals of volcanic earthquakes were about 1,500, although fluctuations, from 1,000 to 2,000 per day, took place at the end of June."

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: C. McKee, RVO.