Hazard Notification System (HANS) for Volcanoes


U.S. Geological Survey
Thursday, September 29, 2022, 2:48 PM HST (Friday, September 30, 2022, 00:48 UTC)

14°13'48" S 169°27'14" W, Summit Elevation 3054 ft (931 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

The earthquake rates related to the swarm under Taʻū Volcano have diminished over the past weeks. One earthquake was reported felt over the past week (September 23) with a magnitude similar to larger earthquakes earlier in this swarm. The satellite data from the previous week observed no volcanic activity.

The National Earthquake Information Center (NEIC) is now publishing preliminary locations of the largest earthquakes that have occurred during the past 30 days of seismic unrest in American Samoa. These locations will appear as dots on a map available at https://earthquake.usgs.gov/earthquakes/map/ and people can report if they felt these events at https://earthquake.usgs.gov/data/dyfi/. However, in the Manuʻa Islands, the earthquake locations and depths continue to be best estimates—large uncertainties exist because the monitoring network is constrained to the east-west orientation of the islands in American Samoa. Thus, a dot only indicates an earthquake occurred and does not provide a precise location. The NEIC will use standard methods for locating earthquakes, and those with poor depth control are assigned a default depth of 6 miles (10 kilometers).

So far, analysis of the earthquakes in the swarm suggests that they occur north of Taʻū Island, and the source of the earthquakes has not moved over time. However, due to processing challenges, some preliminary earthquake locations may appear south of Taʻū Island on the NEIC map. Therefore, the earthquake locations on the NEIC map will change with further refined analyses of the events.   

Samoan and English language alert level and color code definitions: (PDF download, 57.68 kb) https://www.usgs.gov/media/files/volcano-aviation-codes-and-alert-levels-english-and-samoan 

HVO will continue to issue weekly Taʻū Island updates on Thursdays until further notice. Additional messages will be issued as needed.

FAQ Web Resource

Read our Frequently Asked Questions web page for more information. https://www.usgs.gov/observatories/hvo/frequently-asked-questions-about-earthquakes-american-samoa

Volcano Monitoring

Volcanoes in the Manuʻa Islands are monitored with a limited real-time seismic network consisting of four sophisticated seismometers (broadband seismometers)—two on Taʻū Island, one on Ofu Island, and one on Tutuila Island—and eight microseismometers on Tutuila, Taʻū, and Olosega Islands. Two GPS stations provide ground deformation information for Taʻū Island. Satellite remote sensing is another tool being used, which may detect heat, volcanic gas, and volcanic ash associated with early phases of volcanic activity.  

Report what you feel and see.

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

American Samoa Volcanoes

Volcanoes in the U.S. Territory of American Samoa are within the area of responsibility of the U.S. Geological Survey’s Hawaiian Volcano Observatory, based in Hilo on the Island of Hawai‘i.

NOAA Weather and Tsunami resources

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.


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 

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