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American Samoa

American Samoa


Land area: 198 km2 (5 volcanic islands: Tutuila, ‘Aunu’u, Ofu, Olosega, Ta’u; 2 coral islands: Rose, Swains)
EEZ area: 390,000 km2
Political status: An unincorporated and unorganized territory of the United States
Population: 70,260 (July 2003 estimate)
GDP: $510 million, GDPper capita: $5,800
Ethnicity: 93% Pacific Islander, 3% Asian, 1% White, 3% Other
Economy: Rely heavily on US trade, grants and job; tuna canneries are bulk of private sector
Max Elevation above Sea level: 966 m
Island minerals: Pumice (pumicite), pozzolan

Island History

American Samoa was settled circa 600 B.C., perhaps by migrants from the west by way of Indonesia, Vanuatu, Fiji, and Tonga. European explorers first visited the islands in the 18th century, the initial visit being by the Dutch explorer Jacob Roggeveen in 1722. Claim disputes among Germany, the United Kingdom, and the United States were settled by the 1899 Treaty of Berlin, in which the United States received the smaller group of eastern islands (Tutuila and Aunu’u), which it formally occupied the next year. The deed of ces­sion was signed on 17 April 1900, and the U.S. Navy took over administrative duties. Ta’u, Ofu, Olosega (the Manu’a Islands), and Rose Island were ceded to the United States in 1904. Swains Island became part of American Samoa in 1925 by a joint resolution of Congress. In 1951, President Truman transferred administration of the islands to the Department of the Interior.


American Samoa is the southernmost U.S. territory, cen­tered at about 14°S latitude. It is located 3,700 kilometers southwest of Hawai’i and 2,574 kilometers northeast of New Zealand. Tutuila Island possesses an excellent natural deep-water harbor at Pago Pago, which rests at the base of Mt. Matafao, the second highest peak in the territory at 653 m. The highest peak is Lata Mountain at 966 m on Ta’u Island. Ofu, Olosega, and Ta’u Islands form the Manu’a Islands group. Swains Island is an atoll without a channel connecting the central lagoon and the open ocean, whereas Rose Island is a typical atoll with free exchange of water between the lagoon and open ocean.

Geologic Setting

The EEZ of American Samoa encompasses a variety of geologic, morphologic, and tectonic environments. The sediment-covered, deep-water Samoa Basin occupies most of the eastern half of the EEZ. Seamounts of unknown age penetrate through the sediment in the Samoa Basin, mostly near the southern and northern margins of the EEZ. A small piece of the Manihiki Plateau, a feature about 110 million years old, occupies the northeast corner of the EEZ and includes several seamounts. The eastern end of Samoa Ridge occupies the west-central part of the EEZ. This ridge is composed of the geologically young (1.5 million years old to recent) volcanoes that form all the islands within the American Samoa EEZ, except Swains Island. Tutuila Island has a maximum age of about 1.5 million years, and Ta’u Island has had recent volcanic activity. The hot spot (stationary magma chamber deep in the Earth) that created the entire Samoa island chain and ridge (in both Samoa and American Samoa) lies about 45 kilometers east of Ta’u Island (part of the Manu’a Islands) and its active sea-floor manifestation is called Vailulu’u seamount. This seamount is both volcanically and hydrothermally active. Part of Robbie Ridge occupies the northwest corner of the EEZ and includes Swains Island and several seamounts. The age of Robbie Ridge may be similar to that of Manihiki Plateau. The southwest margin of the EEZ is sediment covered and abuts the outer (eastward) margin of the Tonga Trench.

Ephraim Temple
South Pacific Liaison, American Samoa Representative
American Samoa Community College
P.O. Box 2609
Pago Pago, AS 96799

Office: (684) 699-3353
Cell: (684) 731-8169
Email: ephraim@hawaii.edu


USGS Circular 1286 (http://pubs.usgs.gov/circ/2005/1286)



Please consider acknowledging PacIOOS in any distribution or publication of data as follows: Data provided by PacIOOS (www.pacioos.org), which is a part of the U.S. Integrated Ocean Observing System (IOOS®), funded in part by National Oceanic and Atmospheric Administration (NOAA) Award #NA11NOS0120039.