RVO reported that Rabaul caldera's Tavurvur cone was quiet during 1-12 November. At 0516 on 13 November a moderate explosion generated a dense billowing ash cloud that rose 1 km above the crater and drifted NW. A few more explosions continued after that, at irregular intervals; notably on 14 November at 0738, 0851, 1308, 2044, and on 15 November at 1903. Ash plumes from these events also drifted NW. During 1-15 November seismicity was very low, except for events associated with the explosions. Deformation measurements showed slight inflation of the central part of the caldera; the long-term inflationary trend continued.

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)