Geologic Background:
Niuafo`ou ("Tin Can Island") is a low, 8-km-wide
island that forms the summit of a largely submerged
shield volcano. The circular island encloses a 5-km-wide
caldera that is mostly filled by a lake whose bottom
extends to below sea level. The inner walls of the
caldera drop sharply to the caldera lake, named Big Lake
(or Vai Lahi), which contains several small islands and
pyroclastic cones on its NE shore.
Historic Activity:
- At least 10 eruptions since 1814.
- Historical eruptions, mostly from circumferential
fissures on the west-to-south side of the island, and
have often damaged villages on this small ring-shaped
island.
- A major eruption at Niuafo`ou in 1946 forced
evacuation of most of its 1,200 inhabitants.
- Additional eruptions may have occurred in 1947 and
1959.
Recent Activity:
- Series of earthquakes on March 21/22, 1985. A few
days later fresh black pumice was found on shore of Motu
Lahi island in the caldera lake, but no new crater was
found and the lake was not hot or bubbling.
- New hot spring reported in caldera in mid 1999)
Data Sources:
- Smithsonian's SEAN Bulletin (V. 10, No. 9).
- Global Volcanism Network (V. 26, No. 5).
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