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Tectonics basics content - Coggle Diagram
Tectonics basics content
Tectonic hazards and the distribution of tectonic hazards
"Hazard": An event (natural in the case of tectonics) which has the potential to damage persons and or property.
Distribution of hazards
Earthquakes and volcanoes occur on the boundaries of tectonic plates.
This is because said hazards are the result of tension building up within plates as a result of tectonic plate movement.
Earthquakes and volcanoes can occur 'intraplate'
Earthquakes
Earthquakes have been recorded here because the North American plate moves at many different speeds and in many different directions.
This causes tension to build up within the plate, and the Mississippi valley
This tension is released via faults within the plate, causing earthquakes.
Volcanoes
Hotspot volcanoes
Superheating of the mantle creates a 'magma plume' inside the earth. Due to hotter materials having a lower mass per unit value than colder materials, the superheated magma rises towards the crust.
Here, the plume creates a fault within the crust from which volcanic material can be released.
As tectonic plates move, an island chain will form.
The Structure of the earth
Lithosphere
0-100 KM deep
up to 100 KM thick
Solid state
Composed of iron and silicone
300-500 degrees in temp
Asthenosphere
100-250 KM deep
Up to 150 KM thick
Rhein state
Composed of magnesium and iron
1,300 degrees in temp
Mantle
100-2900 KM deep
Up to 2800 KM thick
Liquid
Composed of magnesium, aluminium and silicone
2600-3800 degrees in temp
Outer core
2900-5100 KM deep
Up to 3200 KM thick
Molten
Composed of Iron, nickel and oxygen.
3800-4600 degrees in temp
Inner core
6378 KM deep
Solid
Composed of Iron, nickel and oxygen
5000-5100 degrees in temp
Due to intense pressure which causes the molten core to condense into a solid
Types of crust
Oceanic
<200 million ya
50-100 KM thick
Composed of magnific rocks (igneous)
High density level
Continental
Uo to 4.0 billion ya
125 KM thick
Composed of silicone and oxygen
Buoyant (low density)
Convection cells and plate movement
What is a convection cell?
A convection cell is a process of heating and cooling of magma which results in a ciclical current within the mantle, upon which tectonic plates move.
Heat causes particles in the mantle to gain thermal energy
Lower density
Rises
Reaches the crust and begins to cool
Cooler with a high density
Cools
Reaches the heat source
Heat source (radioactive decay in the core).
Slab pull
Slab pull is the pulling force exerted by a cold, dense oceanic plate plunging into the mantle due to its own weight. The theory is that because the oceanic plate is denser than the hotter mantle beneath it, this contrast in density causes the plate to sink into the mantle.
Ridge push
Ridge push refers to the force exerted by magma on tectonic plates as magma is released from an oceanic ridge.
Fissure eruption
This is evidence of plate tectonics as it is an eruption that occurs along a fault between plates. It indicates plate tectonics as the magma is released from the points at which plates move apart.
Heimay 1973, Iceland sits at the site of a divergent plate and most are fissure eruptions.
Rift valley
A rift valley is a point of rifting between two plates
Evidence of plate tectonics as the rift forms at the point where plates move apart. No moving plates, no rifting,.
East African rift valley
Plate tectonics- theories and evidence.