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Plate Tectonics and Associated
Hazards- Revision Notes
Plate Movement
Earth Structure
The Earth is comprised is of three layers


The core comprises of dense rocks, (density 12) especially of iron and nickel alloys. The inner core
is solid and the outer core is liquid. The outer core is…

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The Lithosphere is the crust and the rigid upper part of the mantle forming a layer which is 80km
thick; this is divided in to 12 larger plates and numerous smaller ones


The asthenosphere is semi-molten material below the lithosphere on which the plates of the
lithosphere `float'. The…

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Alongside each other: TRANSFORM or transcurrent.

Constructive Margins
Plates move away from each other, for example, N. American and Eurasian plates, cresting
mid-ocean ridges such as the Mid Atlantic Ridge. New material appears at the ocean ridge.

Features of Constructive margins
Mid-Ocean Ridges- long high and often complex structures of…

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Volcanoes- heat generated by friction, cause the plate to melt in an area known as the
Benioff zone. This is lighter than the surrounding asthenosphere and rises towards the
surface as magma. This is viscous and forms composite and explosive volcanoes.
Island arcs- magma comes to the surface under water…

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Pahoehoe: rope like surface due to partial cooling
Aa: block, rough lava flow

Major forms of extrusive activity- Volcanoes
Fissure Eruptions
o Occur where an elongated crack in the crust allows lava to spill out over a large area.
o Location: Constructive margins
o Made of: Basaltic rocks
o Eruption:…

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Minor forms of extrusive activity
As well as volcanoes there are other features on the surface due to volcanicity

o Water heated by volcanic activity is intermittently discharged of water
o Ejected as a turbulent eruption of water and vapour
o Water is above boiling point

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Volcanic landsides
Climate change- brought about by the injection of vast amounts of debris into the
atmosphere, which can reduce global temperatures

Intrusive activity
With all volcanic regions, the majority of magma never reaches the surface but cools to form coarser
grained igneous rocks beneath the ground. To form intrusive…

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Case Study
Volcanic eruption- Eyjafjallajokull, Iceland, 2010

Eyjafjallajokull is a volcano 1660m high in the south of Iceland 200km
from the capital of Reykjavik.
Situated on top of the Mid-Atlantic ridge and a constructive margin and a
hot spot which makes eruptions more common.


Ice cap caused the…

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If there was another ash cloud more research has been done in to the effect of ash on
airplane engines it has been discovered that all flights don't need to be grounded plane are
just required to flu at a lower height

Case Study
Volcanic Eruption-Nyiragongo, Democratic Republic of Congo,…

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Long term effects

Those who did flee to Rwanda found that there was a problem with
food and shelter provision in the small country there was also the
worry of cholera and diarrhoea due to cramped conditions
There was also limited drinking water; this meant that many people
suffered from…


Finn McGowan


nas 1 sonny

Connor McDonagh


Awesome, covers everything

Idrees Ahmed


I dont normally type here, but when I do, its only to say that this is the best resource I have found for tectonics for which I am doing the 40 mark essay on. Looking to add more case studies but it has everything on there. Beautiful



amazing, you absolute life saver



thanks so much!!




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