USGS Volcano Notice - DOI-USGS-HVO-2023-02-01T10:21:52-08:00

HAWAIIAN VOLCANO OBSERVATORY MONTHLY UPDATE
U.S. Geological Survey
Wednesday, February 1, 2023, 8:28 AM HST (Wednesday, February 1, 2023, 18:28 UTC)

OFU-OLOSEGA (VNUM #244010)
14°10'30" S 169°37'5" W, Summit Elevation 2096 ft (639 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

No significant activity was detected at Ofu-Olosega Volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the volcano's vicinity.

Background: The islands of Ofu and Olosega in Manuʻa Islands of eastern American Samoa, with a combined length of 3.7 mi (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. The Nu'utele tuff cone, forming a small crescent-shaped island immediately off the west end of Ofu Island, is Holocene. A submarine eruption occurred in 1866, 1.9 mi (3 km) SE of Olosega, along the ridge connecting Olosega with Ta'u Island. From: https://volcano.si.edu/volcano.cfm?vn=244010

More Information: https://www.usgs.gov/volcanoes/ofu-olosega

TA'U ISLAND (VNUM #244001)
14°13'48" S 169°27'14" W, Summit Elevation 3054 ft (931 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

No significant activity was detected at Taʻū Volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the volcano's vicinity. Two continuously recording Global Positioning System (GPS) instruments on Taʻū show no significant surface deformation over the last month.

Background: Taʻū Island is the top of a shield volcano, most of which is beneath the ocean. The volcano has a summit caldera, though landslides have removed the southern part of the caldera. Two rift zones are present on Taʻū, one to the northeast and one to the northwest. The northwest rift zone of Ta‘ū aligns with the Samoan Ridge, a predominantly submarine feature formed from volcanic activity associated with the Samoa hotspot, which is currently located at the Vailulu‘u seamount 25 miles (40 kilometers) to the east of Ta‘ū Island. Ta‘ū and Ofu-Olosega islands are situated on the crest of the Samoan Ridge. A vent erupted between Ta‘ū and Ofu-Olosega in 1866, which is also located on the Samoan Ridge.

More Information: https://www.usgs.gov/volcanoes/ta-u-island

TUTUILA ISLAND (VNUM #244020)
14°17'42" S 170°42' W, Summit Elevation 2142 ft (653 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

No significant activity was detected at Tutuila Volcano during the past month. The USGS National Earthquake Information Center reported no earthquakes of magnitude 2.5 or greater in the volcano's vicinity.

Background: Tutuila Island is an elongated and eroded group of five Pliocene-to-Pleistocene volcanoes constructed along two or three rifts trending SSW-NNE. The Leone Volcanics, in the southernmost part of the island, is the youngest eruption deposit. Eruptions during the Holocene along a 5-km-long N-S-trending fissure formed a group of initially submarine tuff cones and subsequent subaerial cinder cones that produced fresh-looking pahoehoe lava flows. An ash layer overlying a cultural deposit in the SW part of the island was radiocarbon dated at about 440 ± 200 CE (Addison et al., 2006). From: https://volcano.si.edu/volcano.cfm?vn=244020

More Information: https://www.usgs.gov/volcanoes/tutuila-island

Additional Resources

Volcano Alert Levels and Aviation Color Codes in Samoan: https://www.usgs.gov/media/files/volcano-aviation-codes-and-alert-levels-english-and-samoan
Volcano Hazards in the Pacific U.S. Territories https://pubs.er.usgs.gov/publication/fs20193036
NOAA National Weather Service Pago Pago https://www.weather.gov/ppg/
American Samoa Government https://www.americansamoa.gov/

The Hawaiian Volcano Observatory is one of five volcano observatories within the U.S. Geological Survey and is responsible for monitoring volcanoes and earthquakes in Hawaiʻi and American Samoa.

CONTACT INFORMATION:

askHVO@usgs.gov

Subscribe to these messages: https://volcanoes.usgs.gov/vns2/
Summary of volcanic hazards from eruptions: https://www.usgs.gov/observatories/hvo/hazards
Recent earthquakes in Hawaiʻi (map and list): https://www.usgs.gov/observatories/hvo
Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes