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