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Ofu-Olosega volcano

Updated: Mar 4, 2024 12:04 GMT -
Shield volcanoes 639 m / 2,096 ft
United States, Samoan Islands, -14.18°S / -169.62°W
Current status: normal or dormant (1 out of 5)
Last update: 31 Aug 2022 (Smithsonian / USGS Weekly Volcanic Activity Report)

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Typical eruption style: unspecified
Ofu-Olosega volcano eruptions: 1866 

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TimeMag. / DepthDistance/Location


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.
Smithsonian / GVP volcano information

Ofu-Olosega Photos

See also: Sentinel hub | Landsat 8 | NASA FIRMS
Wed, 31 Aug 2022, 14:00

Ofu-Olosega volcano (American Samoa, SW Pacific) - Smithsonian / USGS Weekly Volcanic Activity Report for 24 August-30 August 2022 (New Activity / Unrest)

Data from seismometers recently installed on Tutuila, Ta'u, and Ofu-Olosega islands of American Samoa to monitor an ongoing seismic swarm indicated that the events were related to Ta'u Island and not Ofu-Olosega. HVO lowered the Volcano Alert Level to Normal and the Aviation Color Code to Green on 26 August. The report warned residents of Ofu-Olosega that they could still be significantly affected by events that may take place on or around Ta'u Island. ... Read all
Wed, 24 Aug 2022, 14:00

Ofu-Olosega volcano (American Samoa, SW Pacific) - Smithsonian / USGS Weekly Volcanic Activity Report for 17 August-23 August 2022 (New Activity / Unrest)

HVO reported that an earthquake swarm in the Manu'a Islands of American Samoa continued to be recorded and felt by residents of Ta'u Island and Ofu-Olosega. About 20 earthquakes per hour were recorded by four microseismometers distributed on Tutuila, Ta'u, and Ofu-Olosega Islands. The largest events were estimated to be between magnitudes 2 and 3; most events are too small to be felt. ... Read all