USGS raised Ahyi Seamount in the Northern Mariana Islands to Aviation Color Code Yellow and Volcano Alert Level Advisory at 10:13 ChST (00:13 UTC) on July 16, 2026, after repeated satellite detections of discolored-water plumes near the shallow submarine volcano indicated increased unrest and a potential for activity to breach the ocean surface.
An underwater volcanic eruption is occurring at Ahyi Seamount, located about 18 km (11 miles) southeast of Farallon de Pajaros (Uracas) in the Northern Mariana Islands, part of the Mariana Volcanic Arc in the western Pacific Ocean.
Increased underwater volcanic activity was detected at the Ahyi Seamount, Northern Mariana Islands on May 21, 2023, leading to the Aviation Color Code and Volcano Alert Level being raised to Yellow/Advisory.
Satellite and remote geophysical data show signs of unrest at Ahyi Seamount, Northern Mariana Islands, prompting the USGS to raise the Aviation Color Code to Yellow and the Volcano Alert Level to Advisory on November 28, 2022.
A submarine volcanic activity appears to be taking place in the Ahyi seamount volcano area, the Northern Mariana Islands since mid-October 2022. The last eruption at this volcano took place in 2014.
Starting at 20:35 UTC on April 23, 2014, seismic stations located on Pagan, Sarigan, Anatahan and Saipan (Commonwealth of the Northern Mariana Islands) began recording signals believed to be from an undersea volcanic source. Hydroacoustic sensors on Wake
