Ahyi undersea volcano (Mariana Islands): alert status lowered after calm period since early June

 

Consistent signs of unrest at Ahyi undersea volcano have not occurred for over four weeks. Underwater pressure sensors near Wake Island have not detected clear signs of underwater volcanic activity since early June and the last satellite observations of discolored water near the seamount was seen on May 22, 2023.

Starting mid-October 2022, hydroacoustic sensors at Wake Island, 1,410 miles (2,270 km) east of Ahyi, began recording signals consistent with activity from an undersea volcanic source. In collaboration with the Laboratoire de Geophysique in Tahiti, a combined analysis of the hydroacoustic signals and data from seismic stations located at Guam and Chichijima Island, Japan, confirmed that the source of this activity was at or near Ahyi seamount. Observations of discolored water above the seamount in satellite data confirmed activity at Ahyi. The activity appears to have paused beginning in early April but briefly resumed in late May.
Due to the apparent absence of activity over the last month, the aviation color code is being lowered from YELLOW to UNASSIGNED and the alert level is being lowered from ADVISORY to UNASSIGNED.
Source: Northern Mariana Islands Volcano Observatory volcano activity update 18 July 2023