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  • Country
  • Subregion Name
  • Primary Volcano Type
  • Last Known Eruption
  • 14.175°S
  • 169.618°W

  • 639 m
    2096 ft

  • 244010
  • Latitude
  • Longitude

  • Summit

  • Volcano

There are no activity reports for Ofu-Olosega.

 Available Weekly Reports

There are no Weekly Reports available for Ofu-Olosega.

Summary of eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1866 Sep 12 1866 Nov 15 ± 5 days Confirmed 2 Historical Observations Submarine vent 3 km SE of Olosega

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Richard J J, 1962. Kermadec, Tonga and Samoa. Catalog of Active Volcanoes of the World and Solfatara Fields, Rome: IAVCEI, 13: 1-38.

Stearns H T, 1944. Geology of the Samoan Islands. Geol Soc Amer Bull, 55: 1279-1332.

Stice G D, 1968. Petrology of the Manu'a Islands, Samoa. Contr Mineral Petr, 19: 343-357.

Stice G D, McCoy F W, 1968. The geology of the Manu'a Islands, Samoa. Pacific Sci, 22: 427-457.

Walker G P L, Eyre P R, 1995. Dike complexes in American Samoa. J Volc Geotherm Res, 69: 241-254.

The two triangle-shaped islands of Ofu and Olosega in eastern Samoa, with a combined length of 6 km, are separated by a narrow strait. The islands are formed by two eroded, coalescing basaltic shield volcanoes whose slopes dip to the east and west. Steep cliffs up to 600-m high truncate the northern and southern sides of the islands. The narrow, steep-sided ridge forming the eastern tip of Ofu Island consists of a dike complex. The shield volcano on Ofu is cut on the north by the A'ofa caldera; bathymetry suggests that a caldera may also exist on the Sili shield volcano of Olosega. The Nu'utele tuff cone, forming a small crescent-shaped island immediately off the west end of Ofu Island, is Holocene in age. A submarine eruption took place in 1866 at the opposite end of the two islands, 3 km SE of Olosega, along the ridge connecting Olosega with Ta'u Island.