RVO reported that activity at Ulawun was low during 1-14 July. Emissions from the summit crater consisted of white vapor during 1-7 July, and then changed to occasionally sub-continuous, light gray ash clouds during 8 and 11-14 July. Ash clouds changed to gray-brown on 14 July.

Seismic activity was low from 1 July through the early part of 13 July. RSAM increased from about 0700 on 14 July onwards with the emergence of continuous volcanic tremors until it reached a peak of 700 just after 0300 on 15 July. RVO noted that the last significant volcanic tremors at Ulawun were recorded in May and June 2012.

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)