what is a natural hazard? - aqa geography · 2018. 8. 30. · give me a definition not examples ......
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What is a natural hazard?Give me a definition not examples…
These words might help you…
A natural hazard is a naturally occurring event that might have a negative effect
on people or the environment.
Location of volcanoes and earthquakes
Volcanoes and earthquakes do not
occur in random locations, there are
particular areas around the world with clusters or
patterns of volcanoes and earthquakes
The Earth’s crust
• The crust is not all one piece but is broken into several enormous sections called plates.
• These plates are continuously moving and they meet at a place called plate boundaries or plate margins.
Exam question
• Describe the location of earthquakes and volcanoes (3)
Structure of the earth
• There are two types of crust• The earth’s crust consists of two different types, the crust under the
oceans is a thin layer of heavy rock (basalt) this is known as the‘Oceanic Crust’. The other is thicker and made of lighter rocks (mostlygranite) this is known as the ‘Continental Crust’.
Granite Basalt
The Earths Crust
Together they form the Lithosphere
Convection currents
Convection currents move heat in the mantle. Heat from the interior of the earth rises to the surface. This causes the plates on the surface to move. As they cool they sink back down.
Evidence for plate tectonics?
1. Study of fossils – similar fossils are found on different
continents. This is evidence that these regions were once
very close or joined together.
3. Shape of continents fit together like a jigsaw.
Africa
South
America
2. Pattern of rocks – similar pattern of rock layers on
different continents is evidence that the rocks were once
close together or joined.
Explain why Ice Age 4 is not accurate?
-Think about theories and evidence to prove this
© Boardworks Ltd 200311 of 26
A destructive plate boundary is found
where a continental plate meets an
oceanic plate.
The oceanic plate descends under the
continental plate because it is denser.
As the plate descends it starts to melt
due to the friction caused by the
movement between the plates. This
melted plate is now hot, liquid rock
(magma). The magma rises through
the gaps in the continental plate. If it
reaches the surface, the liquid rock
forms a volcano.
Destructive
Plate
Boundary
© Boardworks Ltd 200312 of 26
Name this plate boundary
Continental crust MantleThe oceanic crust
melts and risesExplosive volcanoes
Oceanic plate
The oceanic crust sinks under
the less dense continental crust Earthquakes occur due to friction
Match the labels to the letters
A B
C D
E
F
G
© Boardworks Ltd 200313 of 26
Constructive
Plate
Boundary
At a constructive plate boundary, two
plates move apart. As the two plates
move apart, magma rises up to fill
the gap. This causes volcanoes at
this type of boundary. However, since
the magma can escape easily at the
surface the volcano does not erupt
with much force. Earthquakes are
also found at constructive
boundaries.
An example of a constructive
boundary is the Mid-Atlantic Ridge.
© Boardworks Ltd 200314 of 26
Conservative plate boundaries
exist where two plates do not
directly collide but slide past
each other along a fault
(weakness).
No volcanoes are found along
these plate boundaries, but
earthquakes do occur.
An example of such a boundary
is the San Andreas Fault in
California.
Conservative
Boundary
What is similar and different between each?
Conservative plate boundary
Destructive plate boundary
Constructive plate boundary
Think about: volcanoes, earthquakes, direction of plate movement, ocean trench, new land formed, type of crust (oceanic or continental), famous examples
Question 1
• Explain how/why earthquakes occur at one type of plate boundary.
• You may use a diagram (6)
Peer marking - Question 1Level 1 (Basic) 1-2 marks
They have given a basic description of plate movement but they have not gone into much detail. For example something like “Plates moving towards each other. One plate pushed below another. As plates move there are shock waves.”
They must have mentioned destructive / conservative / constructive boundaries
Level 2 (Clear) 3-4 marks
They have given a clear description of the cause, and have linked statements.
For example “One plate pushed beneath another. As plates move, they snag and tension builds up. A sudden movement sends out shockwaves, which cause earthquakes.”
Level 3 (Detailed) 5-6 marks
Detailed description of the cause and have linked statements together well. They have also mentioned a case study. They have also used specialist words/terms.
Add a WWW and an EBI
Question 2• Explain why there are earthquakes in and around Indonesia.
• Use this image and your own knowledge (5)
Indonesia
Peer marking – Question 2• Level 1 (Basic) 1-3 marks• They have mentioned the diagram and have given the
names of the plates (once only), on a plate boundary, gives a basic idea of which direction they are moving -not just “plates are moving”
• An example would be “Indo-Australian plate moving towards Eurasian plate. One plate pushed below another. As plates move there are shock waves”.
• They have not gone into much detail and their statements are not linked together.
• Level 2 (Clear) 4-5 marks• They have linked their statements together and have
explained the process in more detail• An example would be “Indo-Australian plate subducted
beneath Eurasian plate. As plates move, they snag and tension builds up. A sudden movement sends out shock waves, which causes earthquakes in Indonesia”.
Question 3• Explain why there are volcanic eruptions in
the area highlighted on the map (5)
Peer marking – Question 3• Level 1 (Basic) 1-3 marks• They have given a basic idea of plate movement but
have not added much detail, e.g. “Plates are moving apart. Magma rises up from below the earth’s crust”.
• They must have stated it is a constructive plate boundary
• Limited evidence of sentence structure. They have spelling mistakes and poor grammar
• Level 2 (Clear) 4-5 marks• They have given a clear explanation of why
earthquakes/volcanic eruptions happen and have linked their statements together e.g. “On a constructive plate boundary where plates are moving apart. As the North American and the Eurasian plates move apart, volcanic eruptions occur as magma rises from the mantle and new crust is formed”.
• They have also mentioned the names of the plates
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