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New Hebrides Plate
The New Hebrides Plate is a micro tectonic plate located in the Pacific Ocean near the island nation of Vanuatu. The plate is bounded on the southwest by the Indo-Australian Plate which is subducting below it. The New Hebrides Subduction Zone is extremely active, producing over 20 earthquakes of magnitude 7 or higher within the past 25 years. The latest quake occurred on April 9, 2008, with a magnitude of 7.3. NH moves 16 mm/a southward with respect to PA by spreading on the South Pandora Ridge. New Hebrides' southward component explains the thrusting earthquakes in the southernmost part of the New Hebrides Trench. The southern part of NH also moves at least 20 mm/a westward with respect to PA.
The New Hebrides Plate is a micro tectonic plate located in the Pacific Ocean near the island nation of Vanuatu. The plate is bounded on the southwest by the Indo-Australian Plate which is subducting below it. The New Hebrides Subduction Zone is extremely active, producing over 20 earthquakes of magnitude 7 or higher within the past 25 years. The latest quake occurred on April 9, 2008, with a magnitude of 7.3. NH moves 16 mm/a southward with respect to PA by spreading on the South Pandora Ridge. New Hebrides' southward component explains the thrusting earthquakes in the southernmost part of the New Hebrides Trench. The southern part of NH also moves at least 20 mm/a westward with respect to PA.
Conway Reef
The Conway Reef plate (CR) is a micro-plate lied in the south Pacific west of Fiji. It is bounded on the east and west by convergent boundaries, the western boundary is with the New Hebrides Plate while the eastern is with the Australian Plate. It's located between two spreading centers. Because spreading rates on the Central Spreading Ridge increase southward from 50 to 80 mm/a, while spreading rates on the West Fiji Ridge decrease southward from 50 to 20 mm/a, CR plate is rotating counterclockwise with respect to all of its neighbors. The North Fiji Fracture Zone is the northern boundary with BR, and its southern boundary with AU is a belt of large sinistral earthquakes on trend with the termination of the New Hebrides Trench.
The Conway Reef plate (CR) is a micro-plate lied in the south Pacific west of Fiji. It is bounded on the east and west by convergent boundaries, the western boundary is with the New Hebrides Plate while the eastern is with the Australian Plate. It's located between two spreading centers. Because spreading rates on the Central Spreading Ridge increase southward from 50 to 80 mm/a, while spreading rates on the West Fiji Ridge decrease southward from 50 to 20 mm/a, CR plate is rotating counterclockwise with respect to all of its neighbors. The North Fiji Fracture Zone is the northern boundary with BR, and its southern boundary with AU is a belt of large sinistral earthquakes on trend with the termination of the New Hebrides Trench.
Futuna
The Futuna plate (FT) is located near the south Pacific island of Futuna. The 200-km-long Futuna Ridge spreading center which trends North from the northeast corner of the Fiji Platform to a point northwest of the Isles de Horne (Fortuna and Alofi islands) with a speading rate of 30 to 60mm/a. Regardless of whether the lithosphere west of Futuna Ridge is part of PA (as interpreted here) or part of BR, the lithosphere east of Futuna Ridge is moving rapidly eastward with respect to PA. There is an E-W alignment of sinistral strike-slip earthquakes appears to separate FT from AU. It possesses an oblique convergent boundary as well.
The Futuna plate (FT) is located near the south Pacific island of Futuna. The 200-km-long Futuna Ridge spreading center which trends North from the northeast corner of the Fiji Platform to a point northwest of the Isles de Horne (Fortuna and Alofi islands) with a speading rate of 30 to 60mm/a. Regardless of whether the lithosphere west of Futuna Ridge is part of PA (as interpreted here) or part of BR, the lithosphere east of Futuna Ridge is moving rapidly eastward with respect to PA. There is an E-W alignment of sinistral strike-slip earthquakes appears to separate FT from AU. It possesses an oblique convergent boundary as well.
Balmoral Reef
The Balmoral Reef plate (BR) is within the North-Fiji Basin. It's a young oceanic crust (<12 Ma) from back arc spreading between New Hebrides and Tonga subduction. It is spreading away from PA at the Tripartite Ridge at rates of 15 mm/a on its northern margin. It also spreads away from NH at the N160 Ridge at rates of 40–50 mm/a or less. The northern and western borders are a divergent boundary while the rest of the borders are transform and convergent boundaries. It has sinistral transform and pull-apart basin boundaries with CR and AU along the North Fiji Fracture Zone. All magnitude-6+ earthquakes within the CR and northeastern AU ‘‘plates’’ have strike-slip mechanisms showing N-S shortening and E-W extension. If these regions are shortening in the N-S direction by 16 mm/a, then the permitted southward component of BR-PA motion can be increased by the same amount.
The Balmoral Reef plate (BR) is within the North-Fiji Basin. It's a young oceanic crust (<12 Ma) from back arc spreading between New Hebrides and Tonga subduction. It is spreading away from PA at the Tripartite Ridge at rates of 15 mm/a on its northern margin. It also spreads away from NH at the N160 Ridge at rates of 40–50 mm/a or less. The northern and western borders are a divergent boundary while the rest of the borders are transform and convergent boundaries. It has sinistral transform and pull-apart basin boundaries with CR and AU along the North Fiji Fracture Zone. All magnitude-6+ earthquakes within the CR and northeastern AU ‘‘plates’’ have strike-slip mechanisms showing N-S shortening and E-W extension. If these regions are shortening in the N-S direction by 16 mm/a, then the permitted southward component of BR-PA motion can be increased by the same amount.
References
Auzende, J.-M., B. Pelletier, and J.-P. Eissen, The North Fiji Basin: Geology, structure, and geodynamic evolution, in Backarc Basins: Tectonics and Magmatism, edited by B. Taylor, pp. 139–175, Plenum Press, New York,
1995a.
Bird, P., Y. Y. Kagan, and D. D. Jackson, Plate tectonics and earthquake potential of spreading ridges and oceanic transform faults, in Plate Boundary Zones, Geophys. Monogr. Ser., vol. 30, edited by S. Stein and J. T. Freymueller, 203–218, AGU, Washington, D. C.,
2002.
Calmant, S., B. Pelletier, P. Lebellegard, M. Bevis, F. W. Taylor, and D. A. Phillips (2003), New insights on the tectonics along the
New Hebrides subduction zone based on GPS results, J. Geophys. Res., 108(B6), 2319.
Bird, P., An updated digital model of plate boundaries, Geochem. Geophys. Geosyst., 4(3), 1027, doi:10.1029/2001GC000252, pp. 25-27, 2003.
Modified Google Earth file by professor Yajing Liu, based on an online module developed by Laurel Goodell, Department of Geosciences, Princeton University. http://serc.carleton.edu/sp/library/google_earth/examples/49004.html.
Auzende, J.-M., B. Pelletier, and J.-P. Eissen, The North Fiji Basin: Geology, structure, and geodynamic evolution, in Backarc Basins: Tectonics and Magmatism, edited by B. Taylor, pp. 139–175, Plenum Press, New York,
1995a.
Bird, P., Y. Y. Kagan, and D. D. Jackson, Plate tectonics and earthquake potential of spreading ridges and oceanic transform faults, in Plate Boundary Zones, Geophys. Monogr. Ser., vol. 30, edited by S. Stein and J. T. Freymueller, 203–218, AGU, Washington, D. C.,
2002.
Calmant, S., B. Pelletier, P. Lebellegard, M. Bevis, F. W. Taylor, and D. A. Phillips (2003), New insights on the tectonics along the
New Hebrides subduction zone based on GPS results, J. Geophys. Res., 108(B6), 2319.
Bird, P., An updated digital model of plate boundaries, Geochem. Geophys. Geosyst., 4(3), 1027, doi:10.1029/2001GC000252, pp. 25-27, 2003.
Modified Google Earth file by professor Yajing Liu, based on an online module developed by Laurel Goodell, Department of Geosciences, Princeton University. http://serc.carleton.edu/sp/library/google_earth/examples/49004.html.