The West Melanesian Trench (previously known as Manus Trench)Note:Also known as Manus Trough or the Melanesian Trench, the later is particularly confusing as the Vityaz Trench has been named the East Melanesian Trench. is an

oceanic trench Oceanic trenches are prominent, long, narrow topography, topographic depression (geology), depressions of the seabed, ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers ...

in the

Bismarck Sea The Bismarck Sea (, ) lies in the south-western Pacific Ocean within the Papua New Guinea, Papua New Guinean exclusive economic zone. It is located north-east of the island of New Guinea and south of the Bismarck Archipelago. It has coastlines i ...

north of

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

delineating the

plate tectonic Plate may refer to: Cooking * Plate (dishware), broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: r ...

boundary between the Caroline and North Bismarck plates. There is only slight seismic activity along both the trench, and its status as an active subduction zone, as proposed in the 2003 general model of major plate movement, is not generally accepted now. A relative motion of or less has, nevertheless, been suggested for the trench, roughly normal to the trench. The

Kilinailau Trench The Kilinailau Trench is an oceanic trench delineating the former oceanic crust boundary between the Pacific Plate and the now inactive North Bismarck Plate, in the area to the west of Papua New Guinea. To its south west is the inactive North S ...

east of New Ireland appears to form a continuation to the south west and is thought to mark the boundary between the Pacific and North Bismarck plates. It is, however, disputed whether the Caroline Plate moves independently from the Pacific Plate. If not, the West Melanesian and Kilinailau trenches form the Pacific-North Bismarck boundary together. The area to the western end of the trench is actively subducting under the Australian Plate at the

New Guinea Trench The New Guinea Trench is a trench along the northern coast of New Guinea. It may represent the seafloor expression of an active subduction zone. The trench generally reaches a depth of less than because of the subduction of thickened oceanic crus ...

. Perpendicular to the two trenches is another trench, the

Mussau Trough Mussau Island is the largest island of St Matthias Islands, Papua New Guinea,Müller, Chris J. "Butterflies of Mussau Island (Lepidoptera: Rhopalocera)." ''A Rapid Biodiversity Survey of Papua New Guinea’s Manus and Mussau Islands'' (2015): 21. ...

separating the Caroline Plate and Pacific Plate. This areas tectonics is still poorly understood.

References

; Sources * * * Tectonic plates Oceanic trenches of the Pacific Ocean Geology of the Pacific Ocean Subduction zones {{tectonics-stub

See also

References