USGS Volcano Notice - DOI-USGS-HVO-2022-08-19T16:50:31-07:00

HVO/USGS Volcanic Activity Notice

Volcano: Ofu-Olosega (VNUM #244010)

Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Issued: Friday, August 19, 2022, 2:01 PM HST
Source: Hawaiian Volcano Observatory
Notice Number: 2022/H370
Location: S 14 deg 10 min W 169 deg 37 min
Elevation: 2096 ft (639 m)
Area: American Samoa

Volcanic Activity Summary:

An earthquake swarm is occurring in the Manuʻa Islands of American Samoa. As the federal entity responsible for monitoring earthquakes and volcanoes in American Samoa, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO) is assigning the Taʻū Island and Ofu-Olosega Volcano Alert Levels to ADVISORY and Aviation Color Codes YELLOW. The designation previously was UNASSIGNED. This designation does not reflect a change in the behavior of either volcano; it simply acknowledges that the number, size, and frequency of earthquakes being felt by people on Taʻū Island and Ofu-Olosega are well above typical background activity (a NORMAL/GREEN alert level). The first reports of felt earthquakes occurred on July 26, 2022. Personal reports and instruments installed over the past week confirm the continuation of elevated earthquake activity.

Data analysis from simple earthquake detection equipment installed on Tutuila, Taʻū, and Ofu-Olosega Islands indicate that the earthquakes are occurring beneath or around the Manuʻa Islands, likely closer to Taʻū rather than Ofu-Olosega. Approximately 20 earthquakes per hour have been recorded for the past several days in the Manuʻa Islands. Estimated magnitudes of the largest earthquakes are between magnitude 2 and 3. The USGS will have more information about the source and cause of the earthquakes next week after expanding the monitoring network.

Volcanoes in the Manuʻa Islands are monitored with a limited real-time seismic network consisting of four microseismometers on Tutuila, Taʻū, and Ofu-Olosega Islands. HVO staff are working with the NOAA Pago Pago National Weather Service Office (NWS) to expand the American Samoa monitoring network. Satellite remote sensing is another tool being used, which may detect heat, volcanic gas, and volcanic ash associated with early phases of volcanic activity.

Current earthquake monitoring is based on the number and relative size of earthquakes and the estimated distance of earthquakes from the microseismometers. Due to the limitations of the current earthquake monitoring equipment, the exact location, depth, and magnitude of these earthquakes are unknown.

Samoan language alert level and color code definitions: https://www.usgs.gov/media/files/volcano-aviation-codes-and-alert-levels-english-and-samoan

Recent Observations:
[Volcanic cloud height] Unknown
[Other volcanic cloud information] Unknown

Remarks:

Hazards

It is unclear if this unrest will escalate to a volcanic eruption. An eruption could pose significant hazards to residents of American Samoa; these hazards include volcanic gases, low-level localized explosions of lava, lava flows, earthquake shaking, and tsunami. Information about these hazards, which are like those in Hawaii, can be found at this HVO website: https://www.usgs.gov/observatories/hvo/hazards. The primary hazard of concern is earthquake shaking, although no damaging earthquakes have occurred as part of this swarm. For information on how to prepare for an earthquake, see https://www.usgs.gov/faqs/what-can-i-do-be-prepared-earthquake.

If you feel shaking and are not near the coast, immediately drop, cover, and hold on until the shaking stops. If you are at the coast, heed the natural tsunami warning signs. If you feel a strong or long-duration earthquake, see a sudden rise or fall of the ocean, hear a loud roar from the ocean, or see a large aerial plume from an eruption, a tsunami may follow, and you should immediately move to higher ground. Pacific Tsunami Warning Center: https://tsunami.gov/

Report what you feel and see.

Residents can assist USGS and NWS monitoring efforts by noting and reporting accurate times when they feel earthquake shaking or notice other changes that might be related to volcanic activity to either the NOAA Pago Pago National Weather Service Office (https://www.weather.gov/ppg/wsopagooffice) or the American Samoa EOC in Pago Pago (684-699-3800).

Contacts:

HVO, askHVO@usgs.gov—best contact for regular reporting and questions.
Ken Hon, HVO Scientist in Charge, USGS khon@usgs.gov
Natalia Deligne, American Samoa Lead Responding Scientist, USGS ndeligne@usgs.gov

Next Notice:

A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, daily scheduled updates are posted at https://www.usgs.gov/programs/VHP/volcano-updates#hvo. Search for past statements here: https://volcanoes.usgs.gov/hans2/search.

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
Volcanoes of American Samoa: https://www.usgs.gov/observatories/hvo/volcanoes-american-samoa
Explanation of Volcano Alert Levels and Aviation Color Codes: https://www.usgs.gov/programs/VHP/volcanic-alert-levels-characterize-conditions-us-volcanoes

(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20220820/0001Z)
(3) Volcano:	Ofu-Olosega (VNUM #244010)
(4) Current Color Code:	YELLOW
(5) Previous Color Code:
(6) Source:	Hawaiian Volcano Observatory
(7) Notice Number:	2022/H370
(8) Volcano Location:	S 14 deg 10 min W 169 deg 37 min
(9) Area:	American Samoa
(10) Summit Elevation:	2096 ft (639 m)
(11) Volcanic Activity Summary:	An earthquake swarm is occurring in the Manuʻa Islands of American Samoa. As the federal entity responsible for monitoring earthquakes and volcanoes in American Samoa, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO) is assigning the Taʻū Island and Ofu-Olosega Volcano Alert Levels to ADVISORY and Aviation Color Codes YELLOW. The designation previously was UNASSIGNED. This designation does not reflect a change in the behavior of either volcano; it simply acknowledges that the number, size, and frequency of earthquakes being felt by people on Taʻū Island and Ofu-Olosega are well above typical background activity (a NORMAL/GREEN alert level). The first reports of felt earthquakes occurred on July 26, 2022. Personal reports and instruments installed over the past week confirm the continuation of elevated earthquake activity. Data analysis from simple earthquake detection equipment installed on Tutuila, Taʻū, and Ofu-Olosega Islands indicate that the earthquakes are occurring beneath or around the Manuʻa Islands, likely closer to Taʻū rather than Ofu-Olosega. Approximately 20 earthquakes per hour have been recorded for the past several days in the Manuʻa Islands. Estimated magnitudes of the largest earthquakes are between magnitude 2 and 3. The USGS will have more information about the source and cause of the earthquakes next week after expanding the monitoring network. Volcanoes in the Manuʻa Islands are monitored with a limited real-time seismic network consisting of four microseismometers on Tutuila, Taʻū, and Ofu-Olosega Islands. HVO staff are working with the NOAA Pago Pago National Weather Service Office (NWS) to expand the American Samoa monitoring network. Satellite remote sensing is another tool being used, which may detect heat, volcanic gas, and volcanic ash associated with early phases of volcanic activity. Current earthquake monitoring is based on the number and relative size of earthquakes and the estimated distance of earthquakes from the microseismometers. Due to the limitations of the current earthquake monitoring equipment, the exact location, depth, and magnitude of these earthquakes are unknown. Samoan language alert level and color code definitions: https://www.usgs.gov/media/files/volcano-aviation-codes-and-alert-levels-english-and-samoan
(12) Volcanic cloud height:	Unknown
(13) Other volcanic cloud information:	Unknown
(14) Remarks:	Hazards It is unclear if this unrest will escalate to a volcanic eruption. An eruption could pose significant hazards to residents of American Samoa; these hazards include volcanic gases, low-level localized explosions of lava, lava flows, earthquake shaking, and tsunami. Information about these hazards, which are like those in Hawaii, can be found at this HVO website: https://www.usgs.gov/observatories/hvo/hazards. The primary hazard of concern is earthquake shaking, although no damaging earthquakes have occurred as part of this swarm. For information on how to prepare for an earthquake, see https://www.usgs.gov/faqs/what-can-i-do-be-prepared-earthquake. If you feel shaking and are not near the coast, immediately drop, cover, and hold on until the shaking stops. If you are at the coast, heed the natural tsunami warning signs. If you feel a strong or long-duration earthquake, see a sudden rise or fall of the ocean, hear a loud roar from the ocean, or see a large aerial plume from an eruption, a tsunami may follow, and you should immediately move to higher ground. Pacific Tsunami Warning Center: https://tsunami.gov/ Report what you feel and see. Residents can assist USGS and NWS monitoring efforts by noting and reporting accurate times when they feel earthquake shaking or notice other changes that might be related to volcanic activity to either the NOAA Pago Pago National Weather Service Office (https://www.weather.gov/ppg/wsopagooffice) or the American Samoa EOC in Pago Pago (684-699-3800).
(15) Contacts:	HVO, askHVO@usgs.gov—best contact for regular reporting and questions. Ken Hon, HVO Scientist in Charge, USGS khon@usgs.gov Natalia Deligne, American Samoa Lead Responding Scientist, USGS ndeligne@usgs.gov
(16) Next Notice:	A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, daily scheduled updates are posted at https://www.usgs.gov/programs/VHP/volcano-updates#hvo. Search for past statements here: https://volcanoes.usgs.gov/hans2/search.