Plate Tectonics - Short Essay
Plate tectonics provide the perfect clues to where and what seismic hazard will occur? Discuss.
It is at the boundaries of the planet’s tectonic plates that most of the world’s major landforms occur and where earthquakes, volcanic and mountain building zones are located. The surface of the planet is made up of seven large and several smaller rigid tectonic plates which float on the semi-molton asthenosphere; the movement of these plates is influenced by the convection cells under the lithosphere, generated by heat from the center of the Earth. Plates can move towardsor away from eachother or in parallel, the type of landform created at the plate boundaries depends on the relative movement of the plates as well as the type of plate, continental or oceanic.
Due to the relatively low density of continental crust it does not sink, however oceanic crust is denser and so does sink into the mantle when the two different types of plate converge at a destructive plate boundary.
As shown in the diagram above, the denser oceanic crust of the Pacific Plate is forced underneath the continental Eurasian Plate at an angle to form a subduction zone with an associated deep sea trench. As the oceanic lithosphere descends, the pressure relaeased can also cause major earthquakes. These earthquakes can happen on land or under the ocean; Tsunamis (such as Krakatoa 1883) caused by submarine earthquakes or by volcanic eruptions are most common at destructive plate boundaries. Volcanoes can also be formed at a destructive plate boundary, for example in New Zealand where the Pacific Plate descends swiftly as it is pushed under the Indo-Austrailian Plate, this causes the crust to melt and magma to rise to the surface. New Zealand and the Japanese Islands (shown in the diagram above) are both examples of Island archs, these are formed when the edge of the less dense continental plate is pushed upwards by the subduction.
Earthquakes are also particularily at common at collision plate
It is at the boundaries of the planet’s tectonic plates that most of the world’s major landforms occur and where earthquakes, volcanic and mountain building zones are located. The surface of the planet is made up of seven large and several smaller rigid tectonic plates which float on the semi-molton asthenosphere; the movement of these plates is influenced by the convection cells under the lithosphere, generated by heat from the center of the Earth. Plates can move towardsor away from eachother or in parallel, the type of landform created at the plate boundaries depends on the relative movement of the plates as well as the type of plate, continental or oceanic.
Due to the relatively low density of continental crust it does not sink, however oceanic crust is denser and so does sink into the mantle when the two different types of plate converge at a destructive plate boundary.
As shown in the diagram above, the denser oceanic crust of the Pacific Plate is forced underneath the continental Eurasian Plate at an angle to form a subduction zone with an associated deep sea trench. As the oceanic lithosphere descends, the pressure relaeased can also cause major earthquakes. These earthquakes can happen on land or under the ocean; Tsunamis (such as Krakatoa 1883) caused by submarine earthquakes or by volcanic eruptions are most common at destructive plate boundaries. Volcanoes can also be formed at a destructive plate boundary, for example in New Zealand where the Pacific Plate descends swiftly as it is pushed under the Indo-Austrailian Plate, this causes the crust to melt and magma to rise to the surface. New Zealand and the Japanese Islands (shown in the diagram above) are both examples of Island archs, these are formed when the edge of the less dense continental plate is pushed upwards by the subduction.
Earthquakes are also particularily at common at collision plate