USGS Volcano Notice - DOI-USGS-HVO-2022-10-03T17:21:37-07:00

Over the past few weeks, the earthquake activity level for Taʻū Island has dramatically decreased and maintained low levels. The earthquake swarm that began in late July is over. As a result, the Hawaiian Volcano Observatory is lowering the volcano alert level to NORMAL and the aviation color code to GREEN. 

An analysis of data from a seismometer installed on Ta‘ū Island from 2005 to 2009 suggests that less than five detected earthquakes per day may be the long-term background seismicity rate. Current earthquake activity is within this background level. 

HVO scientists continue to closely monitor American Samoa earthquakes with four broadband and eight micro-seismometers.  The National Earthquake Information Center is also monitoring and locating earthquakes greater than magnitude 2.5 in American Samoa.  Two Global Positioning System (GPS) receivers on Taʻu Island are being used to monitor any potential ground movements that may occur in the future. Data from the instruments is available from the Taʻū Island website map. https://www.usgs.gov/volcanoes/ta-u-island 

We will begin issuing monthly statements for Taʻū and all other American Samoa volcanoes in the NORMAL/GREEN alert level on the first Thursday of the month that report the volcano's activity level and provide any necessary informational updates. If activity increases significantly, a new Volcano Activity Notification will be issued announcing the change in alert level.