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TECTONIC HAZARDS (EARTHQUAKES (Factors affecting the impacts (The higher…
TECTONIC HAZARDS
EARTHQUAKES
Measuring
A seismometer detects the vibrations caused by an earthquake. It plots these vibrations on a seismograph.
The strength, or magnitude, of an earthquake is measured using the Richter scale. The Richter scale is numbered 0-10.
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Effects
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short-term (immediate) impacts
long-term impacts
social impacts (the impact on people)
economic impacts (the impact on the wealth of an area)
environmental impacts (the impact on the landscape)
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Causes
occur when tension is released from inside the crust. Plates do not always move smoothly alongside each other and sometimes get stuck.
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An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's plates (plate tectonics). Earthquakes can happen along any type of plate boundary.
Earthquake energy is released in seismic waves. These waves spread out from the focus. The waves are felt most strongly at the epicentre
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VOLCANOES
Parts of a volcano
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When this pressure is released, eg as a result of plate movement, magma explodes to the surface causing a volcanic eruption.
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Facts
They are usually coned shaped hills or mountains, but some are slightly different shapes
Volcanoes can happen at the constructive or the destructive boundaries, but not at the conservative boundaries.
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Effects
Positive effects
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The dramatic scenery created by volcanic eruptions attracts tourists. This brings income to an area.
The high level of heat and activity inside the Earth, close to a volcano, can provide opportunities for generating geothermal energy.
Negative effects
If the ash and mud from a volcanic eruption mix with rain water or melting snow, fast moving mudflows are created.
Lava flows and lahars can destroy settlements, which can also change the landscapes.
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TECTONICS
Types of plates
At a compressional, destructive or convergent boundary the plates move towards each other.
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At a tensional, constructive or divergent boundary the plates move apart.
Boundaries/Margines
At a tensional plate boundary plates move apart due to convection currents, the magma then rises and solidifies to form new rock layers once cooled
Congressional boundary the plates move towards each other. it involves a continental and oceanic plate, the oceanic plate slides underneath to form a hill or mountain
Structure of Earth
Outer core: is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel.
Mantle: is the widest section of the Earth. It has a thickness of approximately 2,900 km. The mantle is made up of semi-molten rock called magma.
Inner core: is in the centre and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C.
Crust: is the outer layer of the earth. It is a thin layer between 0-60 km thick. The crust is the solid rock layer upon which we live.
CASE STUDIES
Christchurch
CAUSES
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More shaking on that alluvial plain, amplified during the tremmor
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EFFECTS
100,000 homes damaged and 200 people spent nights in shelters
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185 people were killed and 10,000 homes destroyed
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Haiti 2010
EFFECTS
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4,000 schools were damaged
200,000 people were killed and 300,000 people injured
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5,000 prisoners broke out of prison endangering the public
RESPONCES
Aid from government and other countries were given to support in this situation, though not good as many people stole and looters hurt people who got in their way if they tried getting food.
Some buildings were reinforced to make them earthquake proof, though not all as it was very expensive
Survivors pulled out of the ruble, though this was not very good as many were not rescued
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CAUSES
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The epicentre was 16km deep so very shallow, it was to the west of Port-Au-Prince.
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It happened on the Caribbean plate where a transform slip at a conservative boundary. The pressure built causing friction and tension to build and then release.