RVO reported that during 9-16 June white and gray plumes from Ulawun rose 800-900 m high. Fine ashfall was reported almost daily and affected the NW, W, and SW flanks. During 9-12 June occasional rumbling noises were reported. Fluctuating incandescence from the crater was seen at night on 9 and 10 June from observers in areas to the SW and for a brief period of time on 13 June from areas N.

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)