Question

Which plate boundaries and movements most commonly create earthquakes? Explain how earthquakes can be created by plate tectonics.

Answer 1

1. Divergent Plate Boundaries or Constructive Plate Boundaries. This is where two plates separate. Ridges are created when mantle convection rises up beneath it, with extreme heat, the crust will thin, and the igneous material beneath will eventually. 

2. Divergent, or destructive plate margins cause volcanoes. As the more dense plate subducts, it will melt at depth and the water driven off, will lower the melting point of the overlying mantle wedge, this will create a type of magma. Volcanic Island Arcs are formed at oceanic-oceanic destructive plate margins. The hot, bouyant magma, is less dense that the surrounding rock, so will rise to the surface, and will collect beneath the plate that hasn't been subducted. It will then, under increased pressure erupt under the sea. Over thousands to millions of years, it will keep erupting, to form islands. 

3. Earthquakes are mainly caused at Transform boundaries and Divergent boundaries. At transform boundaries, two plates sliding past eachother, and the build up of friction could lead to earthquakes, if enough stress is built up and then suddenly released, then the energy is released as seismic waves or an earthquake. At divergent boundaries, earthquakes happen along the Benioff zone which is the slope of the subducting plate that is slowly being dragged into the mantle by mantle convection and slab pull. 

4. Divergent boundaries cause orogenisis (mountain building). But only the continental-continental margin where two continental plates are colliding. Because they are the same density, they don't subduct, but they buckle, compress and uplift to form mountains. Just like the himilayas, when the Indian plate collided with the eurasian plate.