Geologic Background:
The largely submarine Kuwae caldera occupies the
area between Epi and Tongoa islands. The 6 x 12 km
caldera contains two basins that cut the NW end of Tongoa
Island and the flank of the late-Pleistocene or Holocene
Tavani Ruru volcano on the SE tip of Epi Island. Native
legends of a major eruption that segmented the
once-connected landmasses of Epi and Tongoa, along with
radiocarbon dates of pyroclastic-flow deposits on Tongoa
Island suggest that the caldera formed about 500 years
ago during one of the largest Holocene eruptions in the
New Hebrides arc. The submarine volcano Karua lies near
the northern rim of the caldera and is one of the most
active volcanoes of Vanuatu.
Historic Activity:
- During the last century, the caldera's active Karua
volcanic cone has emerged at least 6 times, in 1897,
1902, 1906, 1948, 1959, and 1971.
- Each period of activity was accompanied by
explosions.
- The ephemeral island reached a maximum size of 100 m
tall and 1.5 km in diameter in 1949.
Recent Activity:
- The submerged summit area was 50-70 m large at 2-3 m
depth in August 1991. No fumarolic activity was observed
despite a strong sulfur smell.
Data Sources:
- Global Volcanism Network (V. 16, No. 7).
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