Ruby Submarine Volcano(Activation news)

 The Northern Mariana Islands Volcano Observatory reported that a new submarine eruption appeared at the volcano on 15 September.

The new explosion resulted from analysis of seismoacoustic recordings and observations of a submarine plume detected in the satellite imagery on 16 September. Two days before the eruption, a discolored water was monitored at dawn (20:50 UTC) on 14 September. The plume does not breach the ocean surface.

The eruption onset was not observed in geophysical data, however a retrospective investigation of seismoacoustic data of the Saipan monitoring network, 50 km to the southeast of the volcano, captured eruption signals at 04:27 UTC on 15 September. The activity was recorded on other regional geophysical monitoring stations in the Pacific.
The Northern Mariana Islands Volcano Observatory, therefore, raised the alert level for the volcano to Yellow. It is highly likely that further eruptive activity may take place at the volcano.
Ruby, a basaltic submarine volcano that rises to within 230 m of the sea surface near the southern end of the Mariana arc NW of Saipan, was detected in eruption in 1966 by sonar signals (Norris and Johnson, 1969). In 1995 submarine explosions were heard, accompanied by a fish kill, sulfurous odors, bubbling water, and the detection of volcanic tremor.
Source: Northern Mariana Islands Volcano Observatory volcano activity update 19 September 2023