Eastern Gemini Seamount

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 20.98°S
  • 170.28°E

  • -80 m
    -262 ft

  • 258001
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for Eastern Gemini Seamount.

The Global Volcanism Program has no Weekly Reports available for Eastern Gemini Seamount.

Index of Monthly Reports

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.

02/1996 (BGVN 21:02) Submarine eruption; the first recorded historical activity


Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

All times are local (= UTC + 10 hours)

02/1996 (BGVN 21:02) Submarine eruption; the first recorded historical activity

A submarine eruption was observed in the southern New Hebrides island arc (Vanuatu), an area without previously documented historical activity. The activity was first observed by the merchant ship OSCO STAR cruising in this area on 18 February around 1800. It was described as "continual steam and frequent vertical bursts of very dark water." Observations during a New Caledonia Coast Guard flight on 19 February revealed a white zone within a steaming black patch. A similar flight on 22 February enabled a television crew from RFO New Caledonia to take videotape footage for the local news. Observers on that flight noted that the white zone, from which steam was rising, had a diameter of ~400 m. This zone was located inside a wider ellipse, brown-ochre in color, elongated ~4 km down-current. Every 3-9 minutes an explosion sent black products ~20 m above sea level. After each explosion, the diameter of the white area diminished drastically, rising again during the next explosion. The black products were diluted to form the brown-ochre zone. This activity was probably similar to that documented on 18 February.

Located ~100 km S of Anatom Island, about halfway between Yasur Volcano (Tanna Island) and Matthew Island, the Eastern Gemini seamount is one of several seamounts along the southern submarine extension of the New Hebrides island arc. Several basalt samples and one andesite dredged from this seamount in 1989 (Monzier and others, 1993) were described as glassy, vesicular, and extremely fresh (Bargibant and others, 1989). Because all of the samples were devoid of marine animal traces, the activity was described as very recent. The nearby Western Gemini seamount is located near 21.0°S, 170.05°E, at a depth of 30 m below sea level. Well-developed marine life around its summit suggests that its activity is older.

References. Monzier, M., Danyushevsky, L.V., Crawford, A.J., Bellon, H., and Cotten, J., 1993, High-Mg andesites from the southern termination of the New Hebrides island arc (SW Pacific): Journal of Volcanology and Geothermal Research, v. 57, p. 193-217.

Bargibant and others, 1989, ORSTOM Noumea Earth Sciences Report, no. 12, 13 p. (unpublished).

Information Contacts: Bernard Pelletier, Centre ORSTOM de Noumea, BP A5, Noumea, New Caledonia (Email: pelletib@noumea.orstom.nc); Michel Lardy, ORSTOM, BP 76, Port Vila, Vanuatu (Email: lardy@vanuatu.orstom.nc); Michel Monzier and Claude Robin, ORSTOM, AP 17-11-6596 CCI, Quito, Ecuador (Email: monzier@orstom.ecx.ec, robin@orstom.ecx.ec); Jean-Philippe Eissen, Centre ORSTOM de Brest, BP 70, 29280 Plouzane, France (Email: eissen@orstom.fr).

A submarine eruption, the first recorded in historical time from this previously little known seamount, was observed by a passing ship on February 18, 1996. Water discoloration and bursts of very dark water were observed at Eastern Gemini. Overflights as late as the 22nd noted periodic explosions that ejected black products to about 20 m above sea level. Located ~100 km south of Aneityum Island, about halfway between Yasur volcano and Matthew Island, the Eastern Gemini seamount, also known as Oscostar, is one of several seamounts along the southern submarine extension of the New Hebrides island arc. It consists of an elongated NNE-SSW-trending ridge of submarine volcanoes with satellitic cones. Several basaltic samples and one andesitic rock dredged from this seamount in 1989 were described as glassy, vesicular, and extremely fresh.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1996 Feb 18 1996 Feb 22 (in or after) Confirmed 1 Historical Observations

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.



Synonyms
Oscostar

The Global Volcanism Program has no photographs available for Eastern Gemini Seamount.

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Arculus R J, Shipboard Scientists, 2006. Coriolis Troughs and southern New Hebrides arc: primary tectonic results from the CoTroVE (SS06/2004) research voyage. AESC2006, Melbourne, Australia, 5 p.

Monzier M, Danyushevsky L V, Crawford A J, Bellon H, Cotton J, 1993. High-Mg andesites from the southern termination of the New Hebrides island arc (SW Pacific). J Volc Geotherm Res, 57: 193-217.

Smithsonian Institution-GVN, 1990-. [Monthly event reports]. Bull Global Volc Network, v 15-33.

Volcano Types

Submarine

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Rock Types

Major
Basalt / Picro-Basalt
Andesite / Basaltic Andesite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
0
0
0
187

Affiliated Databases

Large Eruptions of Eastern Gemini Seamount Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.