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Year 9 Tectonic Hazards Revision Booklet
What do I need to know?
Topic Page Number Tick when learnt Causes of tectonic plate movement
1
The four different types of tectonic plate margin
1
Describing the distribution of tectonic hazards
2
Why do people continue to live in earthquake prone areas?
2
The causes of earthquakes at different plate margins
3
How can the impacts of earthquakes be reduced
4-5
HIC Earthquake Case Study – New Zealand
6-7
LIC Earthquake Case Study – Nepal
8
Practice 9-17
1
What causes tectonic plates to move?
The Earth's crust is broken up into pieces called plates. Heat rising and falling inside the mantle creates
convection currents. The plates are ‘floating’ on the mantle and the convection currents move the plates.
Where convection currents diverge near the Earth's crust, plates move apart. Where convection currents
converge, plates move towards each other. The movement of the plates, and the activity inside the Earth,
is called plate tectonics.
What are the different types of plate margin?
2
Describing the distribution of tectonic hazards
The 4 Cs
When describing distribution of something you need to say where something occurs and
the way it does – are there any patterns? You need to include the continent that thing
occurs in, the compass direction in that continent, the coastline that thing is on, and give a
country example.
For example: Earthquakes are unevenly distributed around the world. They occur in bands
on tectonic plate boundaries, often on the edges of continents. A number of earthquakes
can be seen on Pacific coast of South America, for example in Chile.
Why do people continue to live in earthquake prone areas?
3
What causes earthquakes?
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.
Earthquakes occur when tension is released from inside the crust. Plates do not always move smoothly alongside each other and sometimes get stuck. When this happens pressure builds up. When this pressure is eventually released, an earthquake tends to occur.
At a conservative plate margin, the plates move past each other or are side by side moving at different speeds. As the plates move, friction occurs and plates become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy, causing an earthquake. The earthquakes at a conservative plate boundary can be very destructive as they occur close to the Earth's surface.
A destructive plate boundary occurs when oceanic and continental plates move together. The oceanic plate is forced under the lighter continental plate. As the plates move, friction occurs and plates become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy, causing an earthquake.
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How can the impacts of earthquakes be reduced?
Despite much research it is not yet possible to predict earthquakes accurately - The best advanced knowledge is 9 seconds which is too short to do anything. Therefore most efforts have been put into preparing for them. Below are some of the ways:
Earthquake Resistant Buildings - These are built with deep foundations with rubber shock absorbers and concrete reinforced with steel. They are designed to twist and sway, have sprinkler systems and gas cut off valves. For example the Transamerica Pyramid in San Francisco, California.
Emergency Plans - These are drawn up, and supplies such as bottled water, medicines, tinned food etc. are stockpiled by individuals or the local area
Earthquake Drills - These are held to practise what to do in the event of an earthquake taking place such as the one held in Japan on Sept 1st every year.
Tsunami Warnings - As Tsunamis occur in the Pacific Ocean there are data collecting devices to give warnings of such an event. They are also being built in the Indian Ocean.
Prediction
Prediction involves using seismometers to monitor earth tremors. Experts know where earthquakes are likely to happen, however it's very difficult to predict when they will happen. Even looking at the timescale between earthquakes doesn't seem to work. Along the San Andreas fault in California, USA, scientists have some of the most advanced technical equipment and education in predicting earthquakes – but they too cannot be exactly sure of when or where an earthquake may strike.
Protection
Many areas prone to earthquake hazards now use building codes. Any new building or adjustment to existing buildings must be built to strict guidelines that would protect people from future earthquake hazards. Protection involves constructing buildings so that they are safe to live in and will not collapse. Some examples of building improvements are:
Rubber shock absorbers in the foundations to absorb the earth tremors.
Steel frames that can sway during earth movements.
Open areas outside of the buildings where people can assemble during an evacuation.
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Low cost methods, such as wire mesh retrofitting, are used in rural areas and developing countries. These are affordable and appropriate to the resources and people living there.
Lightweight roofs and safety glass designed to reduce damage and injury.
Preparation
Hospitals, emergency services and residents practise for an earthquake in earthquake-prone countries. They have drills in all public buildings so that people know what to do in the event of an earthquake. This helps to reduce the impact and increases people's chance of survival.
Responses
Responses are how countries react to an earthquake. They are categorised as follows:
Short-term or immediate response - in the hours, days and weeks immediately after a disaster, it mainly involves search and rescue efforts and helping the injured.
Long-term response - continues for months and years after a disaster and can involve rebuilding damaged or destroyed houses, schools, hospitals, etc. Kick-starting the local economy is also considered a long-term response.
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HIC Earthquake Case Study – Christchurch, New Zealand, 2011
Location
New Zealand is located in the Pacific Ocean in the continent of Oceania. It is South East of Australia and consists of a North and South Island. Its capital city is Wellington.
Causes
The 6.3 magnitude earthquake struck New Zealand at 12:51 on 22 February 2011. The epicentre was 6 miles South East of Christchurch and the focus was very shallow at 3.1 miles. The earthquake occurred on a conservative plate margin where the Pacific Plate slid past the Australian Plate in the opposite direction. It was technically an aftershock from a larger earthquake in 2010 but the impacts were more severe.
Effects
Primary (caused directly by the earthquake) Secondary (result from primary effects)
181 people were killed and around 2,000 people were injured
Business were put out of action for long periods causing losses of income and jobs
Hundreds of kilometres of water and sewage pipes were damaged
Schools had to share classrooms because of the damage to other school buildings
50% + of Central City buildings severely damaged including the city’s cathedral which lost its spire
Damage to roads through liquefaction made it difficult for people and emergency services to move around
Liquefaction (where the ground gets saturated and loses strength) caused lots of damage to roads and buildings
People were affected mentally by the earthquakes and needed support
Part (size of 20 football fields) of the country’s longest glacier was broken off creating a large iceberg
Christchurch could no longer host Rugby World Cup matches so lost the benefits, e.g. tourism and income, they would bring
80% of the city was without electricity
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Responses
Short Term Long Term
Cared for the most vulnerable people and ensured people were safe from dangerous buildings
Paid $898 million in building claims
Chemical toilets were provided for 30,000 residents
Provided temporary housing and ensured all damaged housing was kept water tight
Areas were zoned (green, orange, white, red) to classify damage/cost of repairs
Water and sewerage was restored for all residents by August
International aid was provided in the form of money (around $6-7 million) and aid workers
Roads and houses were cleared of silt from liquefaction by August and 80% of roads/50% of footpaths were repaired
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Key idea: Natural hazards pose major risks to people and property.
1. Define ‘natural hazard’ and give examples.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
_________________________________________
2. Add the events to the table below. Events: earthquake, volcanic eruption, tsunami,
tropical storm, hurricane/typhoon/cyclone, climate change
Event Meaning Lava erupts from a vent in the earth’s crust. This occurs at destructive
and constructive plate boundaries.
Changes to the earth’s atmospheric patterns, especially rainfall and temperature. These changes vary region to region, but in many places they involve increases in temperature.
Different names are given to tropical storms depending on where they occur.
Shaking of the ground due to tectonic movement. This occurs at all plate boundary types.
A series of fast moving, long and high waves resulting from tectonic movement under the ocean floor.
A powerful storm that moves at more than 74 miles per hour. They form over water and spin in an anticlockwise direction, gathering power as they move over water & losing power when they reach land.
3. Complete the paragraph about hazard risk by filling in the gaps with the provided vocabulary. Vocabulary: equipped, earthquakes, probability, density, magnitude, nature, defences, flooding, rebuild, greater, human, frequently, cope, severe.
Hazard risk is the _____________________ that a natural hazard occurs. To count as a
hazard, the event has to affect _____________________ activities. Several factors influence
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hazard risk. One is vulnerability. The denser the population is in an area exposed to natural
hazards, the greater the risk that they will be affected by a natural hazard. For example, an
area with a high population _____________________ along a very active plate boundary
(e.g. San Francisco) is especially vulnerable to earthquakes, and a densely populated
floodplain (e.g. Bangladesh) is especially vulnerable to __________________ caused by
extreme weather. Another factor is capacity to _____________________. The better a
population can cope with an extreme event, the lower the impact will be. For example, HICs
are often better _____________________ than LICs to deal with the impacts of natural
hazards such as flooding or volcanic eruptions., because they are more able to build
__________________, evacuate people, provide swift medical assistance and
________________ quickly. Another factor is that the _________________ of natural
hazards varies considerably. Some hazards can be predicted (e.g. tropical storms) giving
people and governments time to prepare and evacuate, while others cannot be predicted
and happen suddenly (e.g. _____________________) meaning that people are caught
unaware. Some hazards occur more _____________________ than others, increasing
hazard risk. Some hazards are more _______________ than others, e.g. an earthquake of
9.2 on the Richter scale will have a far _______________ hazard risk than one that registers
in at 4.6. To summarise, some key factors affecting hazard risk are: vulnerability, population
density, capacity to cope, level of preparation, hazard type, hazard frequency, and
_____________________.
4. Would hazard risk be greatest for A or B? In the final column, give reasons for your choice. An example has been done for you.
Question A B Risk would be greatest in… (A or B)
Reasons
Where will economic cost be greatest?
Volcanic eruption in a rural area
Volcanic eruption in an urban area
B
Urban areas have more buildings and businesses so insurance and reconstruction costs would be higher. Replacement of belongings is costly for individuals.
Where will economic cost be greatest?
Earthquake in an urban area in a HIC
Earthquake in an urban area in a LIC
Where will human
A tsunami strikes a densely
A tsunami strikes a sparsely
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cost be greatest?
populated coastline
populated coastline
Where will human cost be greatest?
Rising sea levels- mountainous region
Rising sea levels- small Pacific islands
Tectonic hazards
Key idea: Earthquakes and volcanic eruptions are the result of physical processes.
5. The theory of plate tectonics is that….
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
6. Look at the map. The black lines show plate margins. In one sentence, say what a
plate margin is.
___________________________________________________________________________
___________________________________________________________________________
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7. Why do most earthquakes and volcanoes occur near plate margins? In your answer, try to use geographical terms such as: convection currents, tectonic plates, plate boundaries, collision, energy, etc.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
_________________________________________
8. Where do more tectonic hazards occur? Circle the correct answers.
a. On or near plate margins / far from plate margins
b. Near the Pacific Ring of Fire / far from the Pacific Ring of Fire
c. Near coastal areas / inland areas
d. The western coastline of North and South America / the eastern coastline of
North and South America
e. Southern Africa / south and eastern Asia
9. There are three main types of plate margin (destructive, constructive and conservative). For each plate margin type:
a. Draw a diagram showing how the plates move (Towards each other? Apart? Alongside each other?)
b. Write a sentence describing what happens c. Indicate whether earthquakes and/or volcanic eruptions occur as a result d. Give an example (use the map above to help you) e.g. ‘where the South
American and Nazca plates meet’
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Destructive plate margin
a. The plates move together / apart / alongside each other
b. At a destructive plate margin,
________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________.
c. Earthquakes occur here / volcanoes occur here / earthquakes and volcanoes occur here
d. Example: ___________________________________________
Constructive plate margin
a. The plates move together / apart / alongside each other
b. At a constructive plate margin,
_______________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________.
c. Earthquakes occur here / volcanoes occur here / earthquakes and volcanoes occur here
d. Example: ___________________________________________
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Conservative plate margin
a. The plates move together / apart / alongside each other
b. At a conservative plate margin,
_______________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________.
c. Earthquakes occur here / volcanoes occur here / earthquakes and volcanoes occur here
d. Example: ___________________________________________
Key idea: The effects of, and responses to, a tectonic hazard vary between areas of contrasting levels of wealth.
10. Below some effects of and responses to tectonic hazards are listed. Code each one as
either PE (primary effect), SE (secondary effect), IR (immediate response) or LR (long-
term response).
buildings collapse
water pipes burst
disease spreads
evacuation
communication links destroyed
building regulations improved
volunteers arrive to search for survivors
fires spread due to gas pipes bursting
people are injured or killed
income is lost
investment in the area is focussed on
rebuilding
search and rescue teams deployed
evacuation services
medical tents set up
money is donated to purchase medicines
and other supplies
homes are rebuilt at huge expense
trade is made more difficult
economic growth slows
people moved permanently from the area
homelessness
people die of cold and exposure
landslides
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new jobs in the construction industry
tents given out by charities
schools and hospitals rebuilt
people live in refugee camps
shops and businesses ruined
gas pipes burst
rioting
farmland, crops and livestock destroyed
water sources contaminated
the government has to borrow money for
reconstruction
sites of religious and cultural importance
are lost
water is contaminat
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The effects of tectonic hazards are often worse in places that have low
incomes. Select one effect from the list above, and create a flow chart in the
space below to show why the effects may be more devastating in a LIC than a
HIC.
11. To help you do this, complete the table below. Try to include place-
specific details (e.g. place names) and facts and figures (e.g. number of
destroyed houses and lives lost).
HIC named example Earthquake or volcano? _______________________ Place? ____________________________________ Year? ________________________
LIC named example Earthquake or volcano? _______________________ Place? ____________________________________ Year? ________________________
Primary effects
Secondary effects
Immediate responses
Named examples alert! The specification says that you need to ‘Use named examples to show how
the effects and responses to a tectonic hazard vary between two areas of
contrasting levels of wealth.’