RVO reported that gray and brown ash plumes and steam plumes from Rabaul caldera's Tavurvur cone rose to altitudes of 0.9-2.7 km (3,000-8,900 ft) a.s.l. and drifted E and SE during 31 January-5 February. Incandescence from the center of the crater was visible almost every night. On 1 February, ashfall was reported in Kokopo, about 20 km SE. Roaring noises were heard from near-by areas during 1-3 February. On 4 February, a strong smell of hydrogen sulfide gas was reported from Rabaul Town (3-5 km NW).

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)