RVO reported that at 0820 on 2 June a small eruption at Ulawun produced dense gray ash plumes that rose about 3 km above the summit and drifted NW. The elevated activity lasted 10-15 minutes. Minor ashfall was reported in areas downwind, including in Ulamona Mission and on Lolobau Island. Seismicity increased during the event, then dropped back to lower levels. Diffuse white plumes were visible rising from the summit the next day.

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.

Sources: Rabaul Volcano Observatory (RVO), Darwin Volcanic Ash Advisory Centre (VAAC)