USGS Volcano Notice - DOI-USGS-NMI-2023-09-28T17:34:33-07:00

No activity has been detected at Ruby in regional seismic and infrasound data or in satellite imagery over the past week. The plume of discolored water from the September 14-16 eruption was last visible in satellite imagery on September 25, offshore of Saipan to the north but has since dispersed.

It is possible that further eruptive activity could occur at Ruby. There are no local monitoring stations at Ruby, which limits our ability to detect and characterize volcanic unrest there. The volcano is monitored by a regional geophysical monitoring network, including a station at Saipan (50 km away) as well as others in Guam, Japan, and  two arrays of underwater pressure sensors at Wake Island. Analysis of the geophysical data of the September 14-16 eruption was done in collaboration with the Laboratoire de Geophysique in Tahiti. 
 
Ruby is a submarine volcano that rises to within 230 m of the sea surface near the southern end of the Mariana arc northwest of the island of Saipan. The volcano was first detected in eruption in 1966 by sonar signals. In 1995, submarine explosions were heard, accompanied by a fish kill, sulfurous odors, bubbling water, and the detection of volcanic tremor.