Download Inside the Earth, Why do the plates move?

Restless Earth
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Inside the Earth – the interior of the earth.
Earth’s heat island – how the earth’s core drives the process of
plate movement.
Plate tectonics – how the earth’s plates move and plate boundaries.
Boundary Hazards – Which hazards occur at different plate
boundaries.
Volcanoes in the developed and developing world.
Earthquake hazards – their power, impacts and response to them.
Inside the Earth,
This is the cross-section of the Earth, can you label on
the parts and types of crust?
Continental Crust forms the land and is mostly made of
granite. It is low density and about 30-50 km thick.
Oceanic Crust is under the oceans, it is thinner (6-8 km
thick) and denser to it always goes under (is subducted
under) continental crust when they collide.
Why do the plates move?
Convection currents in the liquid
outer core and mantle move the
tectonic plates on the Earth’s surface.
These convection currents are due to
heat rising from the core which is
radioactive.
Plate Tectonics and Plate Boundaries
The earth’s surface is divided up into plates or giant slabs like the pieces
in a giant puzzle which are floating on the liquid mantle and moving around
due to the convection currents. Sometimes the plates are moving apart
and sometimes they move together.
There are four types of plate boundary and each type is associated with
different hazards (earthquakes, volcanoes or both!).
Conservative
Plates slide past each other
Plates move apart
Constructive
Destructive
Collision zone
Plates are moving together but the
oceanic crust is subducted (goes under)
the continental crust so land is
destroyed.
Plates are colliding, as they are both
continental plates the land is forced
upwards making fold mountains like the
Himalayas
Associated with strong violent
earthquakes.
Associated with small earthquakes
and not very dangerous volcanoes,
lava oozes out of the gap!
Associated with strong
earthquakes and very dangerous
and explosive volcanoes.
Associated with very strong
earthquakes and no volcanoes.
NOTE : MAKE SURE YOU CAN DRAW A DIAGRAM WITH LABELS
FOR EACH TYPE OF BOUNDARY.
Volcanoes in the developed and developing world.
What happens when a volcano erupts?
Tephra is the material that
emerges from a volcano.
Pyroclastic flow is a superheated
cloud of ash and dust travelling
rapidly down a volcano.
Lahar is a mudslide formed when
ash mixes with water.
How are people and property affected by
volcanic eruptions? Volcanoes give signs
they are going to erupt and these can be
monitored to predict and eruption.
In MEDCs
volcanoes are
monitored to
reduce the
impacts eg.
Japan. These
countries can
afford to spend
money on
monitoring,
protection and
evacuation.
Concrete shelters are built where people can take shelter from volcanic
bombs and ash, concrete lahar channels divert dangerous mudflows and
evacuation routes are clearly sign posted. Evacuation drills happen to be
sure people know what to do.
What about LEDCS?
People living in LEDCs near volcanoes are at more risk for a number of
reasons (e.g. Mt Nyiragongo in Democratic Republic of Congo).
1) They don’t have anywhere else to go
2) They don’t have insurance.
3) Their governments don’t have the money to invest in monitoring and
protection.
4) Communications are poor so people don’t get enough warning in advance
in order to escape.
LEDCs rely on aid (foreign relief) to help them after a disaster, so
organisations like the UN provide food, blankets and medicine after the
disasters but there are always more deaths and injuries and it takes the
country much longer to recover. (see temporary camp set up below for
all the homeless after the eruption in Dem. Rep of Congo).
Earthquake hazards – their power, impacts and
response to them
Earthquakes can’t be
predicted but we can try
to reduce the deaths,
injuries and damage by
being prepared and
protecting ourselves.
The shaking or seismic
waves are measured on a
seismometer using the
richter scale. This is
the magnitude of the earthquake.
Why do the effects of earthquakes vary?
The magnitude will vary – a magnitude 8 will cause huge
devastation but a magnitude 4 is minor and hardly felt.
 If the epicentre is near an urban area there will be more deaths
and injuries from collapsing buildings.
 If the focus is shallow (near the surface) the waves will be much
bigger and stronger when they reach the surface.
 If a country is less prepared it will suffer more losses – an LEDC
like China for example cannot invest in earthquake proof buildings
or in training their emergency teams to rescue people. In MEDCs
like Japan people do emergency drills and have emergency kits at
home – they are ready and know what to do in an earthquake.
LEDCs like China suffered terribly during
the 2008 earthquake, 70,000 people died,
400,000 were injured and 5 million made
Cross bracing stops
Shock
absorbers
in
the
homeless. After the initial shaking when
floor collapsing.
cross bracers
buildings collapsed, fires broke out and
people died of diseases as food and water
ran out.
Places like China rely on the rest of the
world to help even though they Prime
Minister sent in the army to help straight
away and the Chinese donated lots of
money.
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Strong steel frame is
flexible and won’t crack
Place like Haiti that are very poor relied
completely on foreign aid.
Exam questions -
specimen paper.
Figure 1 shows some major earthquakes that occurred between 2002 and
2009.
1. (a) Describe the range of magnitudes shown in Figure 1. (2)
(b) Explain what is meant by the magnitude of an earthquake. (2)
(c) Suggest reasons why some earthquakes have a much greater death
toll than others. (4)
(Total for Question = 8 marks)
June 2010
a) Name the features shown at X and Y (2)
(b) Describe one way a region affected by earthquakes can prepare for
this hazard. (2)
c) Using an example(s), describe the effects of earthquakes on people
and property. (4)
Other example questions:
1) What type of plate boundary is x and Y?(2)
2) Explain how tectonic plates move (4).
3) Using examples, explain how volcanic eruptions can be predicted (4)
4)Explain why earthquakes happen on destructive plate boundaries (you
may use a diagram to help with your answer (4).
5) Describe the main features of a volcano (2)
6)Explain why some areas are more vulnerable to hazards than others (4)
7) Describe two ways in which buildings in developing / developed
countries can be made more resistant to earthquakes (2)
8) Using examples, describe some of the hazards of living on a
destructive plate margin (4)
9) using an example, describe the impact of a major earthquake on people
and property in the developing/developed world (4)
Notes: