Pago Pago, AMERICAN SAMOA — The U.S Geological Survey (USGS) has lowered the volcano alert level for the Ta’u island volcano as tremors continue to decrease.

The federal government agency says that over the past few weeks, the earthquake activity level for Taʻu Island has dramatically decreased and maintained low levels.

“The earthquake swarm that began in late July is over,” USGS said in a statement early yesterday morning. And as a result, the Hawaiian Volcano Observatory (HVO) — which oversees volcano activities in American Samoa — is lowering the volcano alert level to NORMAL and the aviation color code to GREEN. 

According to USGS, an analysis of data from a seismometer installed on Ta‘u Island from 2005 to 2009 suggests that less than five detected earthquakes (tremors) per day may be the long-term background seismicity rate.

Therefore, current earthquake activity is within this background level. 

HVO scientists continue to closely monitor American Samoa earthquakes with four broadband and eight micro-seismometers. Additionally, the National Earthquake Information Center is monitoring and locating earthquakes greater than magnitude 2.5 in American Samoa.  

Furthermore, two Global Positioning System (GPS) receivers on Taʻu Island are being used to monitor any potential ground movements that may occur in the future.

With the decrease in tremors, the HVO will begin issuing monthly statements for Taʻu and all other American Samoa volcanoes in the NORMAL/ GREEN alert level that report the volcano's activity level and provide any necessary informational updates on the first Thursday of the month .

If activity increases significantly, a new Volcano Activity Notification will be issued.

HVO scientists, who were in American Samoa since early August, returned to Hawai’i more than a week ago, as tremors decreased.