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Restless Earth Revision
Revise the topic
Practice exam technique
Draw
Get into groups of four and number
yourselves.
Draw your plate boundary:
1. destructive
2. collision
3. constructive
2 minutes
4. conservative
Practice drawing these diagrams.
Use them in the exam.
Diagrams
• Four plate boundaries
• Convection currents
• Shield and composite/strato- volcanoes
• Structure of Earth (probably won’t be
asked to draw this one; need to be able
to interpret it)
Review and Rate
• Read the summary of the topic.
• Rate each section: how confident do you
feel with each part?
The Earth’s
Structure
Earth’s interior has a layered structure, with
different composition and physical
properties.
Interpreting a cross-section of the Earth,
with details (temperature, density,
composition, physical state) of layered
structure (including the asthenosphere)
Different types of crust.
Contrast continental and oceanic crust.
OCEANIC
This is heavy (density of 3.0), made of
Minerals rich in Iron and Magnesium
Is about 6-10 km thick on average and is
usually under 200 million years old.
CONTINENTAL
This is lighter (density of 2.6), made of
minerals rich in silica and aluminium,
is about 30-70km thick and is mainly
over 1500 million years old.
Convection Currents
Plumes of
heat rise in
the mantle
Convection
cell in the
mantle
Crust
Solid
Convection
in the liquid
outer core
Earth’s Tectonic Plates and their Boundaries
Mapping the distribution of the three plate margin types, and
naming major plates.
or
Types of Volcano
A shield volcano
A composite or stratovolcano
e.g. Mauna Loa, Hawaii
Very hot, runny, basaltic lava.
Eruptions rarely violent.
Thick, viscous, andesitic lava.
Explosive eruptions.
e.g. Mount Pinatubo,
Philippines
Earthquake Hazards
Contrasting earthquake effects in named locations
Impacts on property versus people.
Loma Prieta earthquake, USA
• Date: Tuesday 17 October
1989, at 17.04
• Magnitude: 6.9 on the Richter
Scale
• Epicentre: in a mountainous
part of Santa Cruz County, 90
km south-east of San
Francisco
• Death toll: 63
• Injured: 3,757
• Homeless: 12,000
• Property cost: $10 billion
Kashmir, Pakistan
• Date: Saturday 8 October 2005
• Magnitude: 7.6 on the Richter
Scale
• Epicentre: Muzaffarabad, the
capital of Pakistaniadministered Kashmir
• Death toll: 75,000
• Injured: 75,000
• Homeless: 2.8 million
• Property cost: $440 million
Impacts worst on property
in developed countries.
Impacts worst on people
in developing countries.
Contrasting economic and social volcanic hazard impacts
Mount St Helens, USA
• Date: Sunday 18th May 1980 at
8.33 am.
• Magnitude: 5 on the Volcanic
Explosivity Index 5
(paroxysmal).
• Homes destroyed: 200
• Death toll: 61 (most as a
result of poisonous gases
which accompanied the blast).
• Evacuated: 2,000 people
• Property cost: $1.1 billion.
Economic impacts worse
in developed countries.
Mount Nyiragongo, DR Congo
• Date: 17th January 2002.
• Magnitude: Gentle; 1 on the
Volcanic Explosivity Index
(VEI).
• Homes destroyed: 12,500
• Death toll: 100 (mostly from
poisonous gas and getting
trapped in lava).
• Evacuated: 400,000
• Lava: hot, runny, basaltic
• Homeless: 120,000
Social impacts worse
in developing countries.
Predicting Earthquakes
• Earthquakes are not as easy to predict as volcanic
eruptions. However, there are still some ways of
monitoring the chances of an earthquake:
• Laser beams can be used to detect plate movement.
• A seismometer is used to pick up the vibrations in the
Earth's crust. An increase in vibrations may indicate a
possible earthquake.
• Radon gas escapes from cracks in the Earth's crust.
Levels of radon gas can be monitored - a sudden
increase may suggest an earthquake.
Preparing for Earthquakes
• People living in earthquake zones need to know what
they should do in the event of a quake. Training people
my involve holding earthquake drills and educating
people via TV or radio.
• People may put together emergency kits and store
them in their homes. An emergency kit may include
first-aid items, blankets and tinned food.
• Earthquake proof buildings have been constructed in
many major cities, eg The Transamerica Pyramid in San
Francisco. Buildings such as this are designed to absorb
the energy of an earthquake and to withstand the
movement of the Earth.
• Roads and bridges can also be designed to withstand
the power of earthquakes.
Earthquake-proof
building design
Developed country
Developing country
Predicting Volcanic Eruptions
Warning signs
Monitoring techniques
Hundreds of small earthquakes are
caused as magma rises up through
cracks in the Earth's crust.
Seismometers are used to detect
earthquakes.
Temperatures around the volcano
rise as activity increases.
Thermal imaging techniques and
satellite cameras can be used to
detect heat around a volcano.
When a volcano is close to erupting Gas samples may be taken and
it starts to release gases. The
chemical sensors used to
higher the sulfur content of these
measure sulphur levels.
gases, the closer the volcano is to
erupting.
Predicting and Preparing for
Volcanic Eruptions
Preparing for Volcanic Eruptions
• Creating an exclusion zone around the volcano.
• Being ready and able to evacuate residents.
• Having an emergency supply of basic provisions,
such as food.
• Funds need to be available to deal with the
emergency and a good communication system
needs to be in place.
Haiti, 2010
Impacts
Response
Problems
Death toll: 200,000
(estimated)
Homeless: 1.5
million (estimated)
Tens of thousands
without food, water
and medical
supplies
Port-au-Prince port
badly damaged
US took control of
Port-au-Prince
airport
UN World Food
Programme
increased food aid
to survivors, e.g. 2
million meals
delivered on one
day
US carried out air
drops
The Haitian
authorities were not
prepared for the
earthquake
Port-au-Prince
airport has limited
capacity
Lack of fuel
Glossary
• You need to be familiar with these words so
that you can:
– understand what questions mean (easier)
– define them (harder)
• Use the glossary sheet as a check list. Tick
them off once when you when you understand
them and again when you can define them.
• Concentrate at first on the terms in bold.
Exam question
(a) Identify one advantage and one disadvantage that
Sakurajima has brought to Japan. (2)
(b) Explain one reason way in which the impact of a
volcanic eruption might be different in a less developed
country. (2)
• More deaths/greater impacts on people. Accept other
reasonable suggestions.
• Explanation:
• People more likely to live in risky locations
• Can’t afford safe, well-built houses so buildings often
collapse
• Communications poor, so warning and evacuation may
not happen (so effectively)
• Poverty
• Slow/inadequate relief effort may lead to lack of
shelter, clean water and food. Disease may spread
• Governments don’t have the money or resources to
provide aid
(c) Using examples, explain how eruptions can be
predicted. (4)
(c) Using examples, explain how eruptions can be
predicted. (4)
Warning signs
Monitoring techniques
Hundreds of small earthquakes are
caused as magma rises up through
cracks in the Earth's crust.
Seismometers are used to detect
earthquakes.
Temperatures around the volcano
rise as activity increases.
Thermal imaging techniques and
satellite cameras can be used to
detect heat around a volcano.
When a volcano is close to erupting Gas samples may be taken and
it starts to release gases. The
chemical sensors used to
higher the sulfur content of these
measure sulphur levels.
gases, the closer the volcano is to
erupting.