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Subduction zone physics: Sinking of the oceanic lithosphere (sediments, crust, mantle), by the contrast of density between the cold and old lithosphere and the hot asthenospheric mantle wedge, is the strongest force (but not the only one) needed to drive plate motion and is the dominant mode of mantle convection. [citation needed]
Obduction zones occurs when the continental plate is pushed under the oceanic plate, but this is unusual as the relative densities of the tectonic plates favours subduction of the oceanic plate. This causes the oceanic plate to buckle and usually results in a new mid-ocean ridge forming and turning the obduction into subduction. [citation needed]
The Hikurangi Subduction Zone is an active subduction zone extending off the east coast of New Zealand's North Island, where the Pacific and Australian plates collide. [2] [3] The subduction zone where the Pacific Plate goes under the Kermadec Plate offshore of Gisborne accommodates approximately 6 cm/year (2.4 in/year) of plate movement while off the Wairarapa shore this decreases to perhaps ...
To map the subduction zone, researchers at sea performed active source seismic imaging, a technique that sends sound to the ocean floor and then processes the echoes that return. The method is ...
Abyssal plains are key geologic elements of oceanic basins (the other elements being an elevated mid-ocean ridge and flanking abyssal hills). In addition to these elements, active oceanic basins (those that are associated with a moving plate tectonic boundary) also typically include an oceanic trench and a subduction zone.
Some troughs look similar to oceanic trenches but possess other tectonic structures. One example is the Lesser Antilles Trough, which is the forearc basin of the Lesser Antilles subduction zone. [8] Also not a trench is the New Caledonia trough, which is an extensional sedimentary basin related to the Tonga-Kermadec subduction zone. [9]
The Cascadia subduction zone is a 960 km (600 mi) fault at a convergent plate boundary, about 100–200 km (70–100 mi) off the Pacific coast, that stretches from northern Vancouver Island in Canada to Northern California in the United States
The zone includes most of the islands of Vanuatu, the Santa Cruz islands of the southern Solomon Islands, [4] and the Loyalty Islands.A number of ocean floor features are related to the zone, in particular the New Hebrides Trench (South New Hebridies Trench) [5] and the North New Hebrides Trench (Torres Trench) which is separated from the southern trench by the d'Entrecasteaux Ridge and the ...