RVO reported that white-to-gray plumes rose less than 500 m from Ulawun during 27 June-9 July, and fine ash fell in areas to the SW, W, and NW. Occasional roaring noises were heard on 28 June and during 5-6 July. A slight increase in seismicity (above moderate levels) indicated by overlapping tremors and Real-time Seismic-Amplitude Measurement (RSAM) values was noted during 5-8 July.

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)