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A study on plate tectonics on the surface of the earth

Hover over the plates to see approximately how much they move each year and the direction of the movement.

Observations show that most earthquakes are associated with tectonic plate boundaries. The theory of plate tectonics can be used to provide a simplified explanation of the global distribution of earthquakes, while some of the characteristics of earthquakes can be explained by using a simple elastic rebound theory. The lithosphere comprises the crust continental and oceanic and the upper part of the mantle.

The Earth's tectonic plates move very slowly relative to each other, typically a few centimetres per year. Hover over the adjacent tectonic map of the world to see how quickly each plate is moving and its direction of movement. Seismologists associate different kinds of seismic activity with what is happening at different types of plate boundaries.

  1. Plates can move past each other in the same plane at a boundary.
  2. The Earth's tectonic plates move very slowly relative to each other, typically a few centimetres per year. This type of boundary is dominated by normal faulting although other types of faulting may be observed.
  3. About 700 million years ago, the Earth is known to have undergone a period of climate change that sent the planet into a deep freeze. Continental collisions result in the creation of mountains and fold belts as the rocks are forced upwards.
  4. The researchers examined a suite of published scientific data on the geological activity during the Neoproterozoic and found many links between plate tectonics and a cooling world.
  5. Where the boundary is between two continental plates, one plate crumples upwards over the other instead of one plate being subducted. Continental collisions A convergent boundary showing mountain formation where one continental plate crumples up and over another continental plate.

Boundaries between tectonic plates are made up from a system of faults. Each type of boundary is associated with one of three basic types of faultcalled normal, reverse and strike-slip faults. Divergent boundary A divergent, or constructive, plate boundary, where new material is produced at the surface. The Mid-Atlantic Ridge is a good example of a constructive plate boundary.

You can see normal faulting at the surface where the Mid-Atlantic Ridge crosses Iceland. Plates can move apart at a boundary. This type of boundary is called a divergent boundary.

Plate tectonics

It is also referred to as a constructive plate boundary, as new material is being produced at the boundary surface. This type of boundary is dominated by normal faulting although other types of faulting may be observed. Hot magma rises from the mantle at mid-ocean ridges pushing the plates apart.

Earthquakes occur along the fractures that appear as the plates move apart. Examples include the East African rift and mid-ocean ridges where two ocean plates are moving apart, such as the regions near the Azores and Iceland.

They are associated with volcanic activity, and the earthquakes in these zones tend to be frequent and small. Convergent boundary Continental collisions result in the creation of mountains and fold belts as the rocks are forced upwards. Plates can move towards each other at a boundary.

This type of is called a convergent boundary. This type of boundary is dominated by reverse faulting although other types of faulting may be observed. Destructive boundary A convergent, or distructive, boundary showing subduction of an oceanic plate under a continental plate. When the boundary is between an oceanic plate and a continental plate, it is also referred to as a destructive plate boundary. At subduction zones, the oceanic plate is pushed down, or subducted, below the continental lithosphere.

As the oceanic slab decends, earthquakes are generated within the slab and at the interface between the plates.

Convergent boundary

Examples include deep ocean trenches like the Peru—Chile trench, where the Nazca plate an oceanic plate is being subducted under the South American continental plate, i. These boundaries tend to produce most of the earthquakes that have magnitudes greater than 6.

Continental collisions A convergent boundary showing mountain formation where one continental plate crumples up and over another continental plate. Reverse faults or 'thrust' faults are found at convergent boundaries. They are associated with mountain ranges, such as the Himalayas or the Andes. Where the boundary is between two continental plates, one plate crumples upwards over the other instead of one plate being subducted.

Examples include the boundary between the Eurasian plate and the African plate, and the boundary between the Indian plate and the Eurasian plate, where the Himalayas are formed where the Eurasian plate is forced up and over the Indian plate.

This type of boundary tends to produce a diffuse zone of activity. Continental collisions result in the creation of mountains and fold belts as the rocks are forced upwards.

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Transform boundary A transform boundary, where two plates slide past each other in the same plane. Strike-slip faults occur at transform boundaries: Plates can move past each other in the same plane at a boundary. This type of boundary is called a transform boundary. This type of boundary is dominated by strike-slip faulting although other types of faulting may be observed. Where two plates slide past each other, earthquakes originate at shallow depths.

California is a good example of this type of boundary. This type of plate boundary is also referred to as a conservative plate boundary, as it involves movement but no loss or creation of material at the surface.

Snowball Earth due to plate tectonics?

Examples include the San Andreas fault and the Anatolian fault. Transform boundaries typically produce large, shallow-focus earthquakes. Although earthquakes do occur in the central regions of plates, these regions do not usually have large earthquakes.