Images

The base of a tuff cone near the coast of Ta‘ū Island in American Samoa. Tuff cones are created from phreatomagmatic processes through the interaction of lava with shallow seawater. This part of the tuff cone contains mostly sand size material that hosts larger blocks and bombs that are up to several feet (one meter) in diameter.

A cliff on Ta‘ū island in American Samoa, exposing part of a tuff cone that was created from phreatomagmatic processes through the interaction of lava with shallow seawater. This part of the tuff cone contains mostly sand-sized material that hosts larger blocks and bombs that are up to several feet (one meter) in diameter.

A view of the summit region of Ta‘ū island, in the Manu‘a island group of American Samoa. Ta‘ū island is the exposed top of a volcano that formed as a result of volcanic activity at the Samoa hotspot. Most of the volcano is under the ocean surface.

A broadband seismometer being installed on Ta‘ū island near Fiti‘uta on August 23, 2022, by the USGS Hawaiian Volcano Observatory, NOAA National Weather Service, and with help from the American Samoan government and local residents of Ta‘ū island.

A broadband seismometer was installed on Ta‘ū island on August 22, 2022, by the USGS Hawaiian Volcano Observatory and NOAA National Weather Service team. This is one of two broadband seismometers that have been placed on Ta‘ū island to help detect earthquakes that started to be felt in the region starting in late July. USGS photo by D. Downs.

An afternoon view of the tuff cone near Faleāsao village located in northwest Ta‘ū island, with the islands of Ofu and Olosega visible in the distance. This tuff cone, which is thousands of years old, formed when hot magma interacted with either shallow groundwater or sea water. There are several tuff cones located within the northwest corner of Ta‘ū island.

A Raspberry Shake microseismometer was installed on Ta‘ū island, American Samoa, on August 19, 2022, by the USGS Hawaiian Volcano Observatory and NOAA National Weather Service team. This is one of several microseismometers that have been placed within the Manu‘a islands to help detect earthquakes in the region that started to be felt in late July. USGS photo by D.

This reference map depicts the volcanic islands of American Samoa, and specifically the Manu‘a Islands of Ofu, Olosega, and Ta‘ū. In recent days and weeks, residents of the islands have been feeling moderate earthquakes, and the Hawaiian Volcano Observatory has deployed several staff members to American Samoa to help monitor the unrest.

View of part of the tuff cone which contains both Faleāsao village and Faleasao Harbor from the northwest part of Taʻū Island, American Samoa. A tuff cone can form when magma and water interact at shallow depths, causing localized explosions.

A Raspberry Shake seismometer was installed at Fitiʻuta Elementary School on Taʻū Island on August 13, 2022, to provide initial data on the swarm of earthquakes that started on the Manuʻa Islands around July 26, 2022.

A Raspberry Shake seismometer was installed at Fitiʻuta Elementary School on Taʻū Island on August 13, 2022, to provide initial data on the swarm of earthquakes that started on the Manuʻa Islands around July 26, 2022.

Reference map showing the location of Ta'u Island and Vailuluʻu seamount, American Samoa.

Service Layer Credits: Sources: Esri, GEBCO, NOAA, National Geographic, Garmin, HERE, Geonames.org, and other contributors

Esri, Garmin, GEBCO, NOAA NGDC, and other contributors

Earthquakes in oceanic environments can generate pressure waves that travel long distances within the ocean itself. Much like seismographs record ground shaking, this energy is recorded by submerged hydrophones measuring pressure changes in water.

Bathymetry of the Vailulu'u crater between the 1999 and 2005 surveys shows the emergence of the Nafanua cone. From the Smithsonian Institution Global Volcanism Program, courtesy of H. Staudigel and S. Hart. 

Porites and Acropora coral species in reef flat pools in the National Park of American Samoa on Ofu, Manuʻa Islands Group, American Samoa.

Broken pillow lavas, colored red by iron oxide, inside Vailulu'u crater. 

NASA Astronaut image of Ta'u Island (Manu'a Islands, American Samoa) in the South Pacific Ocean.

Geologic sketch map of Ta‘ū Island, showing offshore topography. Bathymetric interval: 600 feet. From Stice and McCoy (1968). 

Geologic sketch map of the Manu‘a group of islands in American Samoa. From Stearns (1944).