The Darwin Volcanic Ash Advisory Centre (VAAC) reported that an ash plume at Ulawun had risen 3.7 km (12,000 ft) a.s.l. and drifted E by 1420 on 23 July based on satellite images and information from the Rabaul Volcano Observatory (RVO). The plume had dissipated by 2000.

Source: Darwin Volcanic Ash Advisory Centre (VAAC)

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.