RVO reported that the fissure eruption on Ulawun’s WSW flank had ceased by 4 October, producing only diffuse white-to-gray steam plumes with a blueish tinge from the main coalesced vent. Weak incandescence from the vent was visible at night on 5 October. The lava-flow rate slowed to 3-5 m a day, likely because it was no longer being fed. RSAM decreased to 1,000 units; regular small high-frequency events were recorded during 4-7 October. RVO recommended that the Alert Level be reduced to Stage 2.

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)