RVO reported that on 31 January, a large explosion from Rabaul caldera's Tavurvur cone produced a shockwave. The flanks were showered with lava fragments and an ash plume rose a few hundred meters above the summit and drifted SE and E. Two more explosions occurred later that day. During 31 January-6 February, emissions of steam and of variable amounts of ash produced plumes that rose to a maximum altitude of 2.2 km (7,200 ft) a.s.l. and drifted NE, SE, and E. Roaring noises were audible on 4 February.

Geological Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor utilized by what was the island's largest city prior to a major eruption in 1994. The outer flanks of the asymmetrical shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the east, where its floor is flooded by Blanche Bay and was formed about 1,400 years ago. An earlier caldera-forming eruption about 7,100 years ago is thought to have originated from Tavui caldera, offshore to the north. Three small stratovolcanoes lie outside the N and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and W caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city.

Source: Rabaul Volcano Observatory (RVO)