volcanic and seismic events are major pieces of evidence towards proving thet plate tectonics is valid. discuss the extent to which you agree with this statement

40 mark essay. scored 36/40. Q19 January 2011.

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Preview of volcanic and seismic events are major pieces of evidence towards proving thet plate tectonics is valid. discuss the extent to which you agree with this statement

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Georgina Bennett
`Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics is
valid' Discuss the extent to which you agree with this statement.
The theory of plate tectonics states that the Earth's lithosphere is fragmented into a dozen or more
large and small rigid sections called plates that are moving relative to one another as they float on
top of the underlying semi-molten mantle. If we map out the divisions between these plates, it
would correlate significantly with the distribution of volcanoes around the world. These plates are
either continental, The North American Plate, or oceanic, The Nazca Plate. Tectonic plates are
powered by convection currents, which is the circular movement of magma within the mantle. These
currents are powered by the core, which heats the magma, causing it to rise, cool and fall back down.
This circular motion causes the plates, which float on the mantle, to move.
The entire outer surface of the planet is divided into these plate formations, roughly 30 in total,
which vary in size from over 100,000,000 square miles for example The Pacific Plate to the
Galapagos micro plate at 12,000 square miles. The individual plates are separated by fault lines
which extend from the surface all the way to the asthenosphere, at which point the fault disappears
due to the plasticity of the rock that exists there.
The earth's plates are moved by convection currents in the mantle caused by localised concentrations
of radiation and heat from the earth's core. The plates are constantly in relative motion to each
other, but this motion is extremely slow due to the incredible amount of mass being moved, friction,
and the high viscosity of the asthenosphere.
Volcanoes represent spectacular releases of energy from inside the earth's crust and upper mantle.
There are about 500 active volcanoes which are closely associated with plate boundaries. Magma
rises at the plate margin to create the volcanic activity. During the course of the year only a small
number (20-30) of the active volcanoes erupt. Their eruptive events are relatively short and are
separated by periods of low activity. Earthquakes however are a series of vibrations and shock
waves which are initiated by volcanic eruptions or movements along the plate boundaries. They
result from the build up and the release of pressure created by plate tectonic activity.
Wherever there is movement in the earth's crust earthquakes will form. The build up of pressure in
the earth's crust will build up creating friction. Eventually this pressure will be released and the earth
will shake creating an earthquake. Most earthquakes are caused by sudden movement along fault
plains. The fracture point is known as the foci and the point directly above this on the earth's surface
is called the epicentre.
Modern understanding of the structure of Earth is derived in large part from the interpretation of
seismic studies that measure the reflection of seismic waves off features in Earth's interior. There are
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Georgina Bennett
`Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics is
valid' Discuss the extent to which you agree with this statement.
many types of seismic waves released by the rupture of rocks at the focus. Primary waves (P waves)
travel fastest and are compressional they vibrate in the direction in which they are travelling.…read more

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Georgina Bennett
`Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics is
valid' Discuss the extent to which you agree with this statement.
continental lithospheres, where the less dense plate is pushed beneath the more dense plate, and
becomes part of the asthenosphere forming magma that is andesitic in its nature. This creates the
most violent volcanic activity. Island Arc volcanoes such as Pinatubo and Fold Mountain Volcanoes
such as Nevado Del Ruiz (Andes) are very destructive.…read more

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Georgina Bennett
`Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics is
valid' Discuss the extent to which you agree with this statement.
that the magnetic striping and the construction of the id-oceanic ridge system, the sea floor
spreading hypothesis gained converts and represented another major piece of evidence towards
the theory of plate tectonics.…read more

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Georgina Bennett
`Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics is
valid' Discuss the extent to which you agree with this statement.
formations had once coexisted in an area subsequently separated by movement of lithospheric
plates.
Similar to the age of rocks, studies of fossils found in once adjacent geological formations showed a
high degree of correspondence. Identical fossils are found in bands and zones equidistant from
divergent boundaries.…read more

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Georgina Bennett
`Volcanic and seismic events are major pieces of evidence towards proving that plate tectonics is
valid' Discuss the extent to which you agree with this statement.
of the Pacific Ocean basin). According to Hess, the Atlantic Ocean was expanding while the Pacific
Ocean was shrinking. As old oceanic crust was consumed in the trenches, new magma rose and
erupted along the spreading ridges to form new crust.…read more

Comments

Kayathrie

This amazing! Thank you for sharing :)

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