Ahyi Seamount unrest raises potential for activity to breach ocean surface, Northern Mariana Islands
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.
