Atafu Atoll Seen From Orbit

©NASA

Atafu Atoll

Atafu Atoll in the Southern Pacific Ocean is featured in this image photographed by an Expedition 18 crewmember on the International Space Station.

At roughly eight kilometers wide, Atafu Atoll is the smallest of three atolls (with Nukunonu and Fakaofo atolls to the southeast, not shown) comprising the Tokelau Islands group located in the southern Pacific Ocean. Swains Island to the south (not shown) is also considered part of the Tokelau group.

The political entity of Tokelau is currently a territory of New Zealand. In recent years, public referendums on independence within the islands have been held, but have not received sufficient support to move forward. The primary settlement on Atafu is a village located at the northwestern corner of the atoll indicated by an area of light gray dots in this photograph. The typical ring shape of the atoll is the result of coral reefs building up around a former volcanic island.

Over geologic time, the central volcano has subsided beneath the water surface, leaving the fringing reefs and a central lagoon that contains submerged coral reefs. Erosion and soil development on the surfaces of the exposed fringing reefs has lead to formation of tan to light brown beach deposits (southern and western sides of the atoll) and green vegetation cover (northern and eastern sides of the atoll).

The Tokelau Islands, including Atafu Atoll, suffered significant inundation and erosion during Tropical Cyclone Percy in 2005. The approximate elevation of Atafu Atoll is only two meters above the tidal high water level. Vulnerability to tropical cyclones and potential sea level rise makes the long-term habitability of the atoll uncertain.

ISS018-E-018129 (6 Jan. 2009) larger image

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