"Apart from a few minor steam blast explosions earlier in the year, the level of activity in 1984 has been low. However, in mid-August the amplitudes of volcanic earthquakes increased markedly, and by late August the frequency of occurrence of volcanic earthquakes was increasing.

"Since 23 August occasional explosion sounds from the summit have been heard and occasional small ash clouds have been observed rising 400-500 m above the summit. Weak summit crater glow was reported on 25 August, and on the 28th provincial authorities were alerted to the possibility of further developments."

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.

Information Contacts: C. McKee, RVO.