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Ruby

Photo of this volcano
  • Country
  • Volcanic Region
  • Landform | Volc Type
  • Last Known Eruption
  • 15.605°N
  • 145.572°E

  • -174 m
    -571 ft

  • 284202
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Weekly Report: 4 October-10 October 2023 Citation IconCite this Report

The US Geological Survey lowered both the Aviation Color Code and Volcano Alert Level for Ruby to Unassigned on 6 October, noting that eruptive activity was last detected during 14-15 September. The level of Unassigned reflected the lack of nearby monitoring instruments that could detect lower-level events.

Source: US Geological Survey


Most Recent Bulletin Report: October 2023 (BGVN 48:10) Citation IconCite this Report

Submarine eruption during 14-16 September 2023

Ruby is a submarine volcano that rises to a depth of about 230 m and is located near the S end of the Mariana arc NW of Saipan. Sonar observations detected an eruption was detected in 1966. In 1995, submarine explosions were heard by fishermen, accompanied by a fish kill, sulfurous odors, bubbling water, and volcanic tremor (BGVN 20:10). This report covers a new eruption during September 2023 characterized by seismoacoustic signals and a discolored submarine plume based on reports from the United States Geological Survey (USGS).

During 14-15 September, seismoacoustic signals were detected and a submarine plume was observed in satellite imagery. Volcanic tremor was first observed on a seismometer around 1900 on 14 September. The USGS reported that another signal followed the tremor at 0016 on 15 September, which represented the start of the eruption. A submarine plume of discolored water was visible in geostationary satellite imagery starting around 0416 on 15 September. The discolored plume was also visible at 0650. Seismicity gradually increased throughout the day, peaking around 1426 with a M 4.7 earthquake. An analysis of seismoacoustic data from a geophysical monitoring station on Saipan (50 km SE) showed eruption signals beginning at 1427 on 15 September; the activity was also detected on other regional geophysical monitoring networks in the Pacific. Later in the day on 15 September, the submarine plume had notably weakened and became greener in color and narrower before detaching from the source vent at 1330 on 16 September. Local observers also reported seeing the plume of discolored water. Based on visuals in satellite images, and no additional activity was recorded by geophysical networks after 16 September; no gas-and-steam emissions were detected in satellite data associated with the eruption or in the following days. The Volcano Alert Level (VAL) was raised to Advisory (the second level on a four-level scale) and the Aviation Color Code (ACC) was raised to Yellow (the second level on a four-color scale) on 19 September. In a report issued on 20 September, USGS reported that there was no evidence of further activity detected in regional seismic and infrasound data. The discolored water plume had drifted slowly E and was still visible in satellite imagery in the ocean between Saipan and Anatahan through 25 September; during 21-23 September the discolored plume was visible in satellite imagery N and NNE of Saipan.

On 6 October the ACC and VAL were lowered to Unassigned, noting that eruptive activity was last detected during 14-15 September. The level of Unassigned reflected the lack of nearby monitoring instruments that could detect low-intensity events.

Information Contacts: US Geological Survey, Volcano Hazards Program (USGS-VHP), 12201 Sunrise Valley Drive, Reston, VA, USA, https://volcanoes.usgs.gov/index.html.

Weekly Reports - Index


2023: September | October


4 October-10 October 2023 Citation IconCite this Report

The US Geological Survey lowered both the Aviation Color Code and Volcano Alert Level for Ruby to Unassigned on 6 October, noting that eruptive activity was last detected during 14-15 September. The level of Unassigned reflected the lack of nearby monitoring instruments that could detect lower-level events.

Source: US Geological Survey


20 September-26 September 2023 Citation IconCite this Report

The US Geological Survey reported that no activity had been detected at Ruby in regional seismic and infrasound data or in satellite imagery since the 14-16 September submarine eruption. The plume of discolored water that had detached from the source vent on 16 September drifted E and dispersed; it was between Saipan and Anatahan during 21-22 September, faintly visible N and NNE of Saipan during 23-25 September, and no longer visible by 26 September. The Volcano Alert Level remained at Advisory (the second level on a four-level scale) and the Aviation Color Code remained at Yellow (the second level on a four-color scale).

Source: US Geological Survey


13 September-19 September 2023 Citation IconCite this Report

The US Geological Survey reported that an eruption began at Ruby on 15 September. A submarine plume of discolored water was identified in satellite images at around 0650 but there was no activity above the water surface. Eruption signals began at 1427 on 15 September based on retrospective analysis of seismo-acoustic data from a geophysical monitoring station on Saipan, 50 km SE. The activity was also recorded on other regional geophysical monitoring networks in the Pacific. The submarine plume had detached from the source vent by the morning of 16 September and no additional activity was recorded by geophysical networks. The Volcano Alert Level was raised to Advisory (the second level on a four-level scale) and the Aviation Color Code was raised to Yellow (the second level on a four-color scale).

Source: US Geological Survey


Bulletin Reports - Index

Reports are organized chronologically and indexed below by Month/Year (Publication Volume:Number), and include a one-line summary. Click on the index link or scroll down to read the reports.

10/1995 (BGVN 20:10) Submarine eruption

10/2023 (BGVN 48:10) Submarine eruption during 14-16 September 2023




Information is preliminary and subject to change. All times are local (unless otherwise noted)


October 1995 (BGVN 20:10) Citation IconCite this Report

Submarine eruption

Ruby is a prominent, active submarine volcano in the Mariana Arc (2,300 km S of Tokyo) located NW of the Island of Saipan (figure 1). Although signs of an eruption were first noted by fishermen about 11 October, initial attempts to confirm their early observations failed. On 23 October fishermen reported that they could hear submarine explosions in that vicinity. A vessel from the Wildlife and Emergency Management Office of the Commonwealth of the Northern Mariana Islands confirmed these reports. An Associated Press news report stated that early on 25 October observers had seen dead fish and bubbles, and had smelled a sulfurous odor. On 27 October the Pacific Daily News reported the eruption site as 15°36'22"N, 145°34'33"E (15.6061°N, 145.5758°E). This spot clearly lies on the edifice identified by Bloomer and others (1989, p. 215) as Ruby....

Figure (see Caption) Figure 1. Index map and bathymetric map (depths in meters) showing seamounts near Saipan Island, including the known active centers Esmeralda Bank and Ruby (after Bloomer and others, 1989).

Prior to the eruption, published estimates of the summit elevation suggested a 230-m depth, a refinement an earlier estimate of 549 m (Bloomer and others, 1989, p. 215). On 6 October 1995, the Pacific Daily News report stated the summit was measured at 185-m depth. This newly reported depth remains unconfirmed. According to Mike Blackford, on 23 October a marine depth finder reportedly measured a depth of ~60 m. Although this could be a reflection off the eruptive plume, in the absence of any discussion of instrument type and calibration, this depth remains equivocal.

According to Koyanagi and others (1993), the two seismic stations nearest the eruption were on Saipan (~50 km SE of Ruby) and Pagan islands (~130 km N of Saipan), both too distant to detect subtle seismic effects. Despite the lack of a nearby seismic station, tremor appeared on seismic records at the time of the eruption and the next day. Given the temporal coincidence between the eruption and the tremor, the two were probably associated.

A fish recovered at the eruption site was found to have small particles of ash in its gills and HVO researchers planned to analyze this ash. News of the eruption caused concern about a possible local tsunami and on 25 October, the Commonwealth of the Northern Mariana Islands issued an alert.

Evidence for Ruby's active status came from 1966 hydrophone data, followed later by dredging of extremely fresh volcanic rocks bearing plagioclase, clinopyroxene, and olivine (Bloomer and others, 1989).

References. Bloomer, S.H., Stern, R.J., and Smoot, N.C., 1989, Physical volcanology of the submarine Mariana and Volcano arcs: Bull. Volcanol., no. 51, p. 210-234.

Koyanagi, R., Kojima, G., Chong, F., and Chong, R., 1993, Seismic monitoring of earthquakes and volcanoes in the Northern Mariana Islands: 1993 summary report: Prepared for the Office of the Governor, Commonwealth of the Northern Mariana Islands, Capitol Hill, Saipan MP 96950 (revised 21 February 1993), 34 p.

Information Contacts: Robert J. Stern, Center for Lithospheric Studies, University of Texas at Dallas, Box 830688, Dallas, TX 75083-0688 USA; Robert Koyanagi, USGS Hawaiian Volcano Observatory, Hawaii Volcanoes National Park, HI 96718, USA; Ramon C. Chong, Commonwealth of the Northern Mariana Islands (CNMI), Disaster Control Office, Capitol Hill, Saipan, MP 96950 USA; Mike Blackford, Pacific Tsunami Warning Center, 91-270 Fort Weaver Road, Ewa Beach HI 96706, USA; Associated Press; Pacific Daily News.


October 2023 (BGVN 48:10) Citation IconCite this Report

Submarine eruption during 14-16 September 2023

Ruby is a submarine volcano that rises to a depth of about 230 m and is located near the S end of the Mariana arc NW of Saipan. Sonar observations detected an eruption was detected in 1966. In 1995, submarine explosions were heard by fishermen, accompanied by a fish kill, sulfurous odors, bubbling water, and volcanic tremor (BGVN 20:10). This report covers a new eruption during September 2023 characterized by seismoacoustic signals and a discolored submarine plume based on reports from the United States Geological Survey (USGS).

During 14-15 September, seismoacoustic signals were detected and a submarine plume was observed in satellite imagery. Volcanic tremor was first observed on a seismometer around 1900 on 14 September. The USGS reported that another signal followed the tremor at 0016 on 15 September, which represented the start of the eruption. A submarine plume of discolored water was visible in geostationary satellite imagery starting around 0416 on 15 September. The discolored plume was also visible at 0650. Seismicity gradually increased throughout the day, peaking around 1426 with a M 4.7 earthquake. An analysis of seismoacoustic data from a geophysical monitoring station on Saipan (50 km SE) showed eruption signals beginning at 1427 on 15 September; the activity was also detected on other regional geophysical monitoring networks in the Pacific. Later in the day on 15 September, the submarine plume had notably weakened and became greener in color and narrower before detaching from the source vent at 1330 on 16 September. Local observers also reported seeing the plume of discolored water. Based on visuals in satellite images, and no additional activity was recorded by geophysical networks after 16 September; no gas-and-steam emissions were detected in satellite data associated with the eruption or in the following days. The Volcano Alert Level (VAL) was raised to Advisory (the second level on a four-level scale) and the Aviation Color Code (ACC) was raised to Yellow (the second level on a four-color scale) on 19 September. In a report issued on 20 September, USGS reported that there was no evidence of further activity detected in regional seismic and infrasound data. The discolored water plume had drifted slowly E and was still visible in satellite imagery in the ocean between Saipan and Anatahan through 25 September; during 21-23 September the discolored plume was visible in satellite imagery N and NNE of Saipan.

On 6 October the ACC and VAL were lowered to Unassigned, noting that eruptive activity was last detected during 14-15 September. The level of Unassigned reflected the lack of nearby monitoring instruments that could detect low-intensity events.

Information Contacts: US Geological Survey, Volcano Hazards Program (USGS-VHP), 12201 Sunrise Valley Drive, Reston, VA, USA, https://volcanoes.usgs.gov/index.html.

The Global Volcanism Program has no synonyms or subfeatures listed for Ruby.

Eruptive History

There is data available for 3 confirmed Holocene eruptive periods.

2023 Sep 14 - 2023 Sep 15 Confirmed Eruption VEI: 1

Episode 1 | Eruption (Submarine)
2023 Sep 14 - 2023 Sep 15 Evidence from Observations: Reported

List of 3 Events for Episode 1

Start Date End Date Event Type Event Remarks
2023 Sep 15    - - - - Seismicity (volcanic) Eruption signals began at 1427 on 15 September based on retrospective analysis of seismo-acoustic data from a geophysical monitoring station on Saipan, 50 km SE.
2023 Sep 15    - - - - Observation A submarine plume of discolored water was identified in satellite images at around 0650 on 15 September but there was no activity above the water surface.
2023 Sep 15    - - - - VEI (Explosivity Index) VEI 1

1995 Oct 11 (?) - 1995 Oct 25 Confirmed Eruption VEI: 1

Episode 1 | Eruption (Submarine)
1995 Oct 11 (?) - 1995 Oct 25 Evidence from Observations: Reported

List of 3 Events for Episode 1

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Seismicity (tremor)
   - - - -    - - - - Fauna Kill Aquatic.
1995 Oct 11
(?)
   - - - - VEI (Explosivity Index) VEI 1

1966 Apr 21 ± 7 days - 1966 May 16 ± 15 days Confirmed Eruption VEI: 1

Episode 1 | Eruption (Submarine)
1966 Apr 21 ± 7 days - 1966 May 16 ± 15 days Evidence from Observations: Hydrophonic

List of 2 Events for Episode 1

Start Date End Date Event Type Event Remarks
   - - - -    - - - - Observation SOFAR signals.
1966 Apr 21 ± 7 days    - - - - VEI (Explosivity Index) VEI 1
Deformation History

There is no Deformation History data available for Ruby.

Emission History

There is no Emissions History data available for Ruby.

GVP Map Holdings

Maps are not currently available due to technical issues.

Smithsonian Sample Collections Database

There are no samples for Ruby in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

External Sites