BBC - GCSE Bitesize: Plate tectonics - Higher tier
Yet violent earthquakes related to plate tectonics have caused terrible Most earthquakes and volcanic eruptions do not strike randomly but occur in . primary goals remain unchanged: to issue a short-term prediction; to monitor .. An improved knowledge of the relationship between plate tectonics and. Volcanoes, mountains and earthquakes occur at the edges of tectonic plates - their creation depends on the direction the plates are moving. Earthquakes, volcanoes, and tsunamis are all dangerous natural disasters, but they also have something else in common - tectonic plate.
But the mantle is, in general, solid. It turns out that rocks, along with most other solids, flow by a solid-state, creeping motion, especially when they are hot and given enough time.
Mantle Convection and Plate Tectonics
This is what happens in the mantle. Based on observations of the rates at which the surface of Earth moves, geologists estimate the mantle convectively flows at rates of several centimeters a year.
The heat driving mantle convection has three sources. Mantle convection is the main mechanism by which this heat escapes from the interior of Earth. Plate tectonics refers to the movement of the rigid plates around the surface of Earth.
All about Earthquakes and Volcanoes — Department of Earth Sciences
The outer portion of the planet, or lithosphere, is relatively rigid because it is relatively cold. The lithosphere varies in thickness but is typically a hundred or so kilometers thick. It includes the upper mantle and both the continental and oceanic crust. These plates may move away from, move by, or collide with each other. This process forms ocean basins, shifts continents, and pushes up mountains.
Mantle Convection and Plate Tectonics (article) | Khan Academy
Tectonic plates break apart and diverge where the mantle beneath is upwelling. In such regions mid-ocean ridges develop, and new lithosphere and crust form to replace the material that is moving away.
Where plates converge, usually where the mantle is downwelling, one plate is forced beneath another.
When this involves plates with embedded continental crust, mountain belts such as the Alps and Himalayas form.
- Plate tectonics and volcanoes
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If the collision involves plates with oceanic crust, subduction zones form where one plate descends into the mantle beneath the other plate. Above these subduction zone chains of volcanoes and island arcs like the Aleutians, develop. Below the Aleutian island arc, at depths of to kilometers, water is forced out of the subducted Pacific plate.
This water lowers the melting point of the overlying mantle, causing it to melt.
Plate tectonics - Higher tier
This means that the continents have changed their positions over millions of years. Movement of tectonic plates - Higher tier Volcanoes, mountains and earthquakes occur at the edges of tectonic plates - their creation depends on the direction the plates are moving.
Volcanoes If the plates are moving apart, as at mid-ocean ridges, volcanoes are produced as molten magma is allowed to escape. This happens in Iceland.
This is called subduction.
It produces mountains, like the Himalayas. The friction of the movement can also melt rocks and produce volcanoes. This is also part of the rock cycle, because the plate that dives under the other one becomes part of the mantle [mantle: There are two other ways in which mountains can be formed.Volcanic Activity and Plate Motions
At destructive margins mountain chains can be formed as plates push against each other. If an ocean closes completely then continents can collide. This occurs slowly but the collision would still result in the formation of a mountain chain. Earthquakes If the plates are moving sideways, stresses build up at the plate boundary. When the stress reaches some critical value, the plates slip suddenly, causing an earthquake.