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What happens at deep-ocean trenches?
subdution
Where is old crust pushed down into a trench?
subdution zone
Place where old crust is pushed down into a trench?
subdution zone
Is there a hot spot or a subdution zone near mount st helens?
Mount St. Helens is near a subduction zone.
How does subduction is opposite of spreading boundaries?
it is opposite because subdution sinks in the earth crust and back up and spreading boundaries spread appart.
What happens at deep ocean trenches?
At some points, the oceanic crust bends downward and forms a deep-ocean trench. Then the oceanic crust sinks back into the mantle through a process called subduction.
Why do volcanoes occur at a subdution zone?
the oceanic crust being subducted is Basaltic. It goes through changes from pressure and temperature as it ids subducted. It goes from basalt to Amphibolite and finally at 100km depth eclogite. At the 100 km a lot of the water is forced out of the rock allowing the surrounding area to liquidize. Since it is liquid it is less dense then the solid area and rises. as it reached into the Continental or ocean crust it melts the surrounding area, and magma rises forming a volcano.
Where does subdution occur?
Subduction (I believe that's what you meant) occurs at CONVERGENT boundaries, where two plates collide and the less dense one remains and the denser one sinks. An example of subduction is two oceanic plates colliding. Oceanic plates contain mainly basalt, which is dense. The oceanic plate closer to a heat source (hot spot, volcano) would remain in place while the denser plate sinks (cold water is denser than hot water so it sinks) below the other. When an oceanic plate and a continental plate collide, the oceanic plate sinks because granite (what continental plates are composed of mainly) is less dense than basalt, therefore the oceanic plate would sink. However, when two continental plates collide, because both plates are made of granite and are not very dense, they push and shape the land into mountains.
