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Report on Ulawun (Papua New Guinea) — 1 November-7 November 2023


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 1 November-7 November 2023
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2023. Report on Ulawun (Papua New Guinea) (Sennert, S, ed.). Weekly Volcanic Activity Report, 1 November-7 November 2023. Smithsonian Institution and US Geological Survey.

Weekly Report (1 November-7 November 2023)


Papua New Guinea

5.05°S, 151.33°E; summit elev. 2334 m

All times are local (unless otherwise noted)

Rabaul Volcano Observatory (RVO) reported that diffuse white plumes rose from Ulawun’s summit crater on 1 November. A low booming noise was heard at 1945. Minor crater incandescence began to be visible later that day at around 2100 and was observed until sunrise. White emissions were visible early on 2 November but by the afternoon clouds of gray-to-brown ash were occasionally observed when weather permitted observations. Crater incandescence was again visible at nightfall but was more intense than the previous night and remained visible until sunrise. Seismicity was dominated by low-level volcanic tremor. Small, low-frequency earthquakes occurring at long intervals began to be recorded at some point before 2300 on 1 November; an increase in both magnitude and frequency occurred after 2300 and the signal again intensified after 0800 on 2 November. Seismicity slightly declined around 0800 on 3 November and remained at those levels at least through noon. The Alert Level remained at Stage 2 (on the four-level scale).

Geological Summary. 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.

Source: Rabaul Volcano Observatory (RVO)