Rabaul Volcano Observatory (RVO) reported that activity at Ulawun was low during 6 December 2023-9 January 2024. During periods of good visibility white steam plumes of variable densities were seen rising from the summit crater. On 19 December visibility was poor, though during a brief clear period, observers noted brown-tinged steam plumes. On 31 December residents of Noau Village photographed dense brown ash plumes rising a few hundred meters above the summit and drifting W, and a small pyroclastic flow descending the NNE flank. The Alert Level remained at Stage 1 (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)