Year 9
Restless Earth
Earthquakes and Plate Tectonics
Revision PowerPoint
Revise Earthquakes and restless earth
using your exercise books, this
PowerPoint and relevant sections of BBC
Bitesize and learn on the internet
geography websites:
http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/
http://www.geography.learnontheinternet.co.uk/topics/volcanoes.html
http://www.geography.learnontheinternet.co.uk/topics/earthquakes.html
http://www.geography.learnontheinternet.co.uk/topics/structureofearth.
The Earth is divided into 4 layers
•
•
•
•
Crust
Mantle
Outer (Liquid) core
Inner (Solid) Core
• Make sure you can describe and label the
features of the 4 layers...
Very thin solid “Skin”
that we live on. As thin
as 8 km in places. The
crust is split into plates
that “Float” on the
Mantle.
5500-6000 Degrees Celsius. Iron
and Nickel. 1260 Km thick. Solid
due to the pressure.
Liquid Iron and Nickel. 2220 Km
thick.
Forms about half the earth. Solid
nearer the surface, but hot and soft
nearer the core.
The Earth gets hotter towards the centre!
The Earth is densest at the inner core!
Layer 1 - The Crust
• The top layer of the earth – it’s surface its about 5 to
70 km’s deep
• Its like an orange!
• The crust is made up of plates – 12 in total
• The plates sit in a layer called the lithosphere
• But they don’t quiet fit
together and are
always moving around
• This means that they
are rubbing against
each other, into each
other, over each other
or away from each
other
Layer 2 – The Mantle
• The plates are moved around as they are
powered from the Mantle
• The mantle is about 3000 km’s deep
• Its consists of semi-molten rock and liquid
metal.
• The energy produces
convection currents because it
is over 3000 degrees celsius.
• This causes the plates to
move.
• Its like orange peel in a bowl
of moving water.
Layer 3 & 4 – The Core
• The outer core is 1300 km’s in
depth and consists of semi
liquid molten metal
• It is between 4000 – 5000
degrees
• The Core is made up of 2 parts
• The inner and outer core
• The inner core is 800 km in depth
and 6000 degrees celsius.
• The two parts are cause of the
magnetic field
This video clip compares the earth to a
peach...
• http://www.bbc.co.uk/learningzone/clips/structure-of-the-earth/9117.html
The earth’s
crust is
divided into
plates
The plates “float” on
the Mantle. They
move. They are
dragged along by
convection currents
in the mantle.
Plate boundaries are
where the different
plates meet.
The red dots are Active volcanoes
Volcanoes and 98%
of earthquakes
occur along the
plate boundaries
__ Tectonic Plate boundaries
There are 4 types of Plate
boundary.
The names we used for them are:
Constructive
Destructive
Conservative
Collision
Make sure you can describe and explain each one.
Ensure you can explain how they cause earthquakes
and volcanoes.
Constructive Plate Boundary
From geog1
Destructive Plate Boundary
From geog1
Conservative Plate Boundary
This type of plate boundary occurs in California, USA where the North American and Pacific
plates slide past each other. The example there is known as the San Andreas fault.
It explains why Los Angeles and San Francisco experience earthquakes.
From geog1
Collision Plate Boundary
This type of plate boundary creates mountains for example the Himalayas where the
Indo-Australian plate is colliding with the Eurasian plate.
This causes earthquakes in India and China.
From geog1
Where is New Zealand?
How do plate boundaries effect New Zealand
North Island
New Zealand
Why do the plate boundaries cause
problems for New Zealand?
• New Zealand 7 August 2012
• http://www.bbc.co.uk/news/world-asia-19160562
• New Zealand 23 December 2012
• http://www.bbc.co.uk/news/world-asia-16313416
What might be happening in New Zealand
The Indo Australian plate is being forced under the
South Island of New Zealand.
The Pacific Plate is being forced under the North Island.
Thesea are destructive Plate boundaries.
Destructive Plate Boundaries
Make sure you can
explain how a
destructive plate
boundary causes
earthquakes and
volcanos.
Earthquakes
Earthquakes are the
“Shaking of the earth’s crust caused by
rock movement”.
You need to be able explain the keywords, explain how earthquakes are measured, explain how
earthquakes occur and describe and explain a real earthquake by using a case study. You alos
need to be able to explain how we try to reduce the effects of earthquakes.
Keywords:
• Magnitude
How strong an earthquake is
• Focus
The place deep inside the earth
where the rocks are moving and
gives way
• Richter Scale
The scale on which the strength
of an earthquake is measured
• Aftershock
Smaller earthquakes after the
main large earthquake.
• Seismometer
An instrument used to measure
the strength of the
earthquake.
• Epicentre
The point at the surface directly
above the focus
Richter Scale
Seismometer
The Richter Scale
A scale used to record the magnitude of earthquakes.
Detected by seismometers,
but people there won’t even
certain there has been an
earthquake.
0
1
2
Windows shatter and break
3
Light fittings sway and
ornaments fall off shelves.
4
5
6
Major catastrophe
7
Buildings damaged, walls
crumble, windows break,
signs fall off shops
8
9
Richter scale no.
No. of
Typical effects of this magnitude
earthquakes per
year
< 3.4
800 000
Detected only by seismometers
3.5 - 4.2
30 000
Just about noticeable indoors
4.3 - 4.8
4 800
Most people notice them, windows rattle.
4.9 - 5.4
1400
Everyone notices them, dishes may break,
open doors swing.
5.5 - 6.1
500
Slight damage to buildings, plaster
cracks, bricks fall.
6.2 6.9
100
Much damage to buildings: chimneys fall,
houses move on foundations.
7.0 - 7.3
15
Serious damage: bridges twist, walls
fracture, buildings may collapse.
7.4 - 7.9
4
Great damage, most buildings collapse.
> 8.0
One every 5 to 10 years
Total damage, surface waves seen,
objects thrown in the air.
Why is California at risk?
Why is Kobe in Japan at risk?
Watch these video clips
http://www.bbc.co.uk/learningzone/clips/1989-santa-cruz-california-earthquake/5722.html
http://www.bbc.co.uk/learningzone/clips/earthquakes-in-california-and-japan/14078.html
Now look at the maps on the next slideIt’s all to do with the North American plate
and Pacific plate moving together at different
speeds.
Look at these two
maps…
The San Andreas
Fault runs along a
conservative plate
boundary
The North
American
plate moves
at 3cm per
year.
The Pacific
plate moves
at 5cm per
year.
It’s as if one of the plates is
remaining still. As they slide past
each other, they get locked
together. Enormous pressure
builds up. The rock eventually
gives way and the plates lurch
forward. The energy released is
felt as an earthquake.
Therefore California is at risk,
so what happened in 1994?
Watch this video to find out…
http://www.bbc.co.uk/mediaselector/check/player/nol/newsid_6720000/newsid_6722300?redirect=672
2349.stm&news=1&nbwm=1&nbram=1&bbwm=1&bbram=1&asb=1
Think about your radio news scripts.
Be ready to describe with evidence
what happened.
MAGNITUDE AND EPICENTER
The Northridge, Los Angeles earthquake
occurred at 4:30 a.m. local time on January 17,
1994. Northridge is located about 30 km
northwest of Los Angeles. This earthquake had
a 6.9 magnitude. The duration was about 10
seconds to 20 seconds.
DEATH TOLL
The number of fatalities in the
Northridge earthquake was 57. About
9000 people were injured. The fact
that the earthquake occurred at 4:30
a.m. minimized the death toll.
STRUCTURAL DAMAGE
The Northridge earthquake caused extensive damage to parking structures and freeway
overpasses (Motor way bridges and fly overs) For example, a section of the Antelope Valley
Freeway collapsed onto the Golden State Freeway south of Newhall. Also, a section of the
Santa Monica Freeway in West Los Angeles collapsed.
In addition, a 2500-car parking garage at the California State University at Northridge
collapsed. This structure was about 3 km away from the epicenter.
Furthermore, the Northridge earthquake triggered landslides in the Santa Susana
Mountains, Santa Monica Mountains, and western San Gabriel Mountains. These landslides
damaged homes, blocked roads and damaged water lines.
Year 9 Earthquakes
Haiti 12 January 2010
Where is
Haiti?
Why is it at
risk?
First reports…
http://news.bbc.co.uk/1/hi/8455629.stm
Immediate aftermath
http://news.bbc.co.uk/1/hi/world/americas/8458307.stm
Eyewitness to aftershock, descriptions of damage.
http://news.bbc.co.uk/1/hi/world/americas/8460575.stm
Death toll rising, Aid arriving.
•http://www.bbc.co.uk/news/world-latin-america-11740647
•12 Nov 2010 Cholera outbreak- link to infrastructure
damaged in earthquake.
Haiti Earthquake!
1653hrs Tuesday 12 January 2010
• Magnitude 7 on the Richter scale
• At least 52 aftershocks within 24
hours.
• An estimated three million people
were affected by the quake
• 230,000 people killed.
• 300,000 injured
• 1,000,000 homeless.
• 250,000 homes destroyed.
• 30,000 business premises
destroyed.
Key facts to
use in a
case study!
Reducing the Effects of earthquakes
Remember your mind maps?
Predict
Plan
Act
We try to prepare for natural disasters by predicting where and when they might occur,
planning for the disaster and taking long and short term actions to help us prepare and
cope with them.
You will need to use your mind maps about Predict, Plan & Act during our revision lesson
and during the homework clubs to recap our discussions, but the next slides will help.
Can we Predict Earthquakes?
In Turkey scientists have
been trying…
But is it accurate
enough?
• http://www.bbc.co.uk/pr
ogrammes/p00gmsgt
Why can’t we use
these methods to
save lives in the
short term?
Plan:
Can we protect our transport links and buildings?
•
http://www.bbc.co.uk/learningzone/clips/engineering-earthquake-resistant-structures/5725.html
• What would be required to earthquake proof
the infrastructure in an area close to a plate
boundary?
• Why would this be hard for some LICs?
Earthquake proof homes?
Reducing the effects of earthquakes
ideas.
• 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.
These could be expensive and may require high levels of engineering skill
to build.
• Emergency Plans - These are drawn up, and supplies such as bottled
water, medicines, tinned food etc are stockpiled by individuals or the local
authorities. LICs and the citizens of poorer countries may not be able to
afford to make plans or have stores of food and water to distribute when
disaster strikes.
• 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 September 1st
every year when the population of Japan practise what to do if an
earthquake occurs. Children in California in the USA are taught a “Drop,
Cover and Hold on” drill to follow. Practise drills and education cost money
that nor all LICs may be able to afford to provide.
Bridges, power stations, medical
facilities, building regulations,
emergency kits, practice drills,
warning systems, earthquake advice
centres
Tiltmeters, falling water levels, radon gas,
foreshocks and animal behaviour.
Act
Reducing the
effects of
earthquakes
Building Regulations, Checking bridges, Educating the populations about what to do,
Emergency kits and Personal planning.