The mostly submarine Tavui caldera lies off the NE tip of the Gazelle Peninsula north of Rabaul caldera. The caldera was first discovered during a bathymetric cruise in 1985. The SW wall of the roughly 10 x 12 km caldera cuts the NE end of the peninsula and extends from Tavui Point at the northern tip of the peninsula SE to Laweo Point. The 7,100-year-old Raluan Ignimbrite, initially thought to have originated from Rabaul, is now thought to have been produced by an eruption of Tavui. A basaltic scoria layer immediately underlies the rhyolitic ignimbrite, and the introduction of basaltic magma was considered to have triggered the rhyolitic eruption. The lack of a major low-velocity region detectable beneath the caldera during a seismic tomography survey suggests that it is not currently active.