A group of small islands SE of Tongoa Island, part of the northern group of the Shepherd Islands, were considered to be remnants of a once-larger landmass that foundered during the Holocene. Ewose, Buninga, and Tongariki islands lie on the rim of a proposed caldera thought to be one of several formed in the central volcanic chain of Vanuatu about 2000 years ago (Crawford et al. 1988, Macfarlane et al. 1988). Eissen et al. (1991) did not find evidence for a caldera at this location. Pyroclastic rocks intruded by dikes are exposed on Ewose, whereas Buninga and Makura are largely composed of tilted lava flows. Tongariki consists of remnants of a basaltic stratovolcano with dacitic pumiceous tuffs in low-lying areas.