Ofu-Olosega

Ofu and Olosega are two islands formed from two shield volcanoes in the United States Territory of American Samoa. Volcanic activity in American Samoa is within the area of responsibility of the U.S. Geological Survey’s Hawaiian Volcano Observatory, based in Hilo on the Island of Hawai‘i.

Volcanoes in American Samoa

Facts Block

Location: American Samoa

Latitude: 14.18° S

Longitude: 169.62° W

Elevation: 639 (m) 2,096 (f)

Volcano type: Shield

Composition: Basalt

Most recent eruption: unknown

Nearby towns: Olosega, Ofu

Threat Potential: Low*

*based on the National Volcano Early Warning System

Hawaiian Volcano Observatory (HVO)

[

](https://www.usgs.gov/observatories/hvo/about-hawaiian-volcano-observatory)

The USGS Hawaiian Volcano Observatory monitors volcanoes in American Samoa

Learn about HVO

HVO Quick Links

• Volcanic Hazards in Pacific U.S. Territories Fact Sheet
• Volcanoes of American Samoa Fact Sheet
• Media Newsroom
• Subscribe to Volcano Updates
• Volcano Watch - HVO's weekly article

NASA Astronaut image of Ofu-Olosega islands (Manu'a Islands, American Samoa) in the South Pacific Ocean. NASA Space Shuttle image ISS002-E-6878 (https://eol.jsc.nasa.gov/SearchPhotos/photo.pl?mission=ISS002&roll=E&fr…).

News

Volcano Minute — Volcano monitoring work in American Samoa: aloha to talofa

September 24, 2026

Volcano Minute — Volcano monitoring work in American Samoa: aloha to talofa

Volcano Watch — From aloha to talofa: USGS Hawaiian Volcano Observatory monitors American Samoa

September 24, 2026

Volcano Watch — From aloha to talofa: USGS Hawaiian Volcano Observatory monitors American Samoa

Photo & Video Chronology — Fieldwork in American Samoa

September 14, 2026

Photo & Video Chronology — Fieldwork in American Samoa

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Publications

August 8, 2024

Volcanoes of American Samoa Volcanoes of American Samoa

Authors

Natalia I. Deligne, Drew T. Downs, Elinor Lutu-McMoore, Steven Sobieszczyk, Wendy K. Stovall

By

Volcano Hazards Program, Volcano Science Center, Ofu-Olosega, Ta'u Island, Tutuila Island

Volcanic hazards in the Pacific U.S. Territories Volcanic hazards in the Pacific U.S. Territories

The Commonwealth of the Northern Mariana Islands, Guam, and American Samoa lie along the western side of the famed Pacific Ring of Fire. Here, the processes of active island and submarine volcanoes produce activity both underwater and in the atmosphere that poses potential hazards to the daily lives of residents and travelers. Since 2000, CNMI volcanoes have erupted six times, and one...

Authors

Gabrielle Tepp, Brian Shiro, William W. Chadwick

By

Volcano Hazards Program, Volcano Science Center, Agrigan, Ahyi Seamount, Alamagan, Anatahan, Asuncion, Daikoku Seamount, East Diamante, Esmeralda Bank, Farallon de Pajaros, Fukujin Seamount, Guguan, Kasuga 2, Maug Islands, Ofu-Olosega, Pagan, Ruby, Sarigan, South Sarigan Seamount, Supply Reef, Ta'u Island, Tutuila Island, Zealandia Bank, Subduction Zone Science

October 22, 2018

2018 update to the U.S. Geological Survey national volcanic threat assessment 2018 update to the U.S. Geological Survey national volcanic threat assessment

When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location. Assessing the relative threats posed by U.S. volcanoes identifies which volcanoes warrant the greatest risk-mitigation efforts by the U.S. Geological Survey and its partners...

Authors

John W. Ewert, Angela K. Diefenbach, David W. Ramsey

By

Volcano Hazards Program, Volcano Science Center, Agrigan, Ahyi Seamount, Alamagan, Anatahan, Asuncion, Belknap, Black Butte Crater Lava Field, Black Rock Desert Volcanic Field, Blue Lake Crater, Carrizozo Lava Flow, Cascade Range Weekly Update, Cinnamon Butte, Clear Lake Volcanic Field, Coso Volcanic Field, Crater Lake, Craters of the Moon Volcanic Field, Daikoku Seamount, Davis Lake Volcanic Field, Devils Garden Lava Field, Diamond Craters Volcanic Field, Dotsero Volcanic Center, East Diamante, Esmeralda Bank, Farallon de Pajaros, Fukujin Seamount, Glacier Peak, Guguan, Haleakalā, Hell's Half Acre Lava Field, Hualālai, Indian Heaven Volcanic Field, Jordan Craters Volcanic Field, Kama‘ehuakanaloa, Kasuga 2, Kīlauea, Lassen Volcanic Center, Long Valley Caldera, Mammoth Mountain, Markagunt Plateau Volcanic Field, Maug Islands, Mauna Kea, Mauna Loa, Medicine Lake, Mono Lake Volcanic Field, Mono-Inyo Craters, Mount Adams, Mount Bachelor, Mount Baker, Mount Hood, Mount Jefferson, Mount Rainier, Mount Shasta, Mount St. Helens, Newberry, Ofu-Olosega, Pagan, Red Hill-Quemado Volcanic Field, Ruby, Salton Buttes, San Francisco Volcanic Field, Sand Mountain Volcanic Field, Sarigan, Soda Lakes, South Sarigan Seamount, Supply Reef, Ta'u Island, Three Sisters, Tutuila Island, Ubehebe Craters, Uinkaret Volcanic Field, Valles Caldera, Wapi Lava Field, Weekly Update, West Crater Volcanic Field, Yellowstone, Zealandia Bank, Zuni-Bandera Volcanic Field

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