First eruption at Ruby volcano since 1995, Northern Mariana Islands

ruby volcano eruption plume seen on september 19 2023 via sentinel-2 satellite

An eruption at submarine Ruby volcano, near the southern end of the Mariana arc, was detected on Thursday, September 14, 2023. This was based on seismoacoustic signals from a monitoring station in Saipan and satellite imagery that captured a submarine plume. The last known eruption at this volcano took place in 1995.

A submarine plume was detected in satellite imagery at approximately 20:50 UTC on September 14.

Before the detection of this plume, geophysical data had not captured the onset of the eruption. However, a closer look at seismoacoustic data from a geophysical monitoring station situated 50 km (31 miles) southeast of the volcano, in Saipan, revealed eruption signals that began at 04:27 UTC on September 15. This volcanic activity was also identified by other regional geophysical monitoring systems throughout the Pacific.

ruby volcano eruption plume seen on september 15 2023 via sentinel-3 satellite
Image credit: Copernicus EU/Sentinel-3, The Watchers. Acquired on September 15, 2023

By September 16, satellite images showed that the plume had dispersed, and subsequent monitoring from geophysical networks didn’t detect any further volcanic activity. Due to the eruption at Ruby, officials have now elevated the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY.

Given the recent activity, experts believe that there’s a possibility of future eruptions at Ruby. Monitoring of the volcano is done by a comprehensive regional geophysical network, which includes stations in locations such as Saipan as well as in Guam, Japan, and even an underwater pressure sensor located at Wake Island. The analysis of this geophysical data was conducted in association with the Laboratoire de Geophysique situated in Tahiti.

The plume was again detected in satellite imagery acquired by the Sentinel-2 satellite on September 19.

ruby volcano eruption plume seen on september 19 2023 via sentinel-2 satellite
Image credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers. Acquired on September 19, 2023

Ruby is a submarine volcano with a peak almost 230 m (755 feet) below the sea surface. The first known eruption from this volcano was recorded in 1966, detected via sonar signals. Almost three decades later, in 1995, submarine explosions from Ruby were heard. These explosions were accompanied by a series of disturbances including a fish kill, the release of sulfurous odors, water bubbling, and the detection of volcanic tremor.


1 Volcano Observatory Notice for Aviation (VONA) for Ruby (VNUM #284202) – USGS – Issued at 03:06 UTC on September 19, 2023

Featured image credit: Copernicus EU/Sentinel-2, EO Browser, The Watchers. Acquired on September 19, 2023


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