Plate tectonics essay

1168 Words Sep 21st, 2014 5 Pages
Assess the strength of the relationship between tectonic processes and major landforms on the earth’s surface.

Tectonic processes have been responsible for the major landforms across the Earth’s surface. These processes are controlled by the convection currents rising from the Earth’s mantle.

Firstly, one place where tectonic activity occurs is at oceanic to oceanic constructive plate boundaries. Here two plates diverge or move away from each other, pushed apart by huge convection currents In the earth’s mantle. These convection currents are initiated by heat energy produced from radioactive decay in the earth’s core. As the convection currents move the plates away from each other, there is a weaker zone in the crust and an
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Here, two plates meet and the denser oceanic lithosphere of the Nazca plate is forced down under the more buoyant continental lithosphere of the South American plate, descending at an angle into the mantle in a process called subduction. This is marked on the ocean surface by the presence of the Peru-Chilie trench. The friction between the plates prevents the subducting oceanic plate from sliding smoothly. As it descends it drags against the overlying plate causing both fracture and deform. This results in frequent shallow focus earthquakes The subduction of the Nazca plate under southern Chile produced the largest earthquake ever recorded, with a magnitude of 9.5 in 1960. Volcanoes are also created here as one plate subducts and partially melts; the magma rises up through fissures and can reach the surface. The type of lava here is andesitic, very high in silica and not very hot resulting in a composite volcano being formed out of layers of ash and lava. The cascade mountain range is an example of where a destructive plate boundary has caused the Juan de Fuca plate to subduct under the North American plate. This resulted in 15 composite volcanoes being formed, one of them, Mount St. Helens.

Similar to the peru-chile region, the Japanese islands are situated in a subduction zone. In the northwestern margin of the pacific oceans, the pacific plate

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