Section A, Q1, The Restless Earth:
What the syllabus says:
Key Idea:
The Earth’s crust is unstable,
especially at
plate margins.
Unique landforms occur at
plate margins
People use these landforms as
a resource
and adapt to the conditions
within them.
Volcanoes are hazards
resulting from
tectonic activity. Their
primary and
secondary effects are positive
as well
as negative. Responses change
in the
aftermath of an eruption.
Supervolcanoes are on a much
bigger
scale than other volcanoes and
an eruption
would have global
consequences.
Earthquakes occur at
constructive,
destructive and conservative
plate margins.
The effects of earthquakes
and responses
to them differ due to
contrasts in levels of
wealth.
Tsunamis are a specific
secondary effect and
can have devastating effects
in coastal areas.
Specification Content:
Distribution of plates;
contrasts between continental and oceanic plates.
Destructive, constructive and conservative plate margins
Location and formation of fold mountains,
Location and formation of ocean trenches,
Location and formation of composite volcanoes and
shield volcanoes.
A case study of one range of fold mountains.
The ways in which they are used – farming,
Hydro Electric Power, mining, tourism and how
people adapt to limited communications, steep
relief, poor soils.
Characteristics of different types of volcanoes.
A case study of a volcanic eruption – its cause;
primary and secondary effects; positive and negative impacts;
immediate and long term responses.
Monitoring and predicting volcanic eruptions.
The characteristics of a supervolcano and the
likely effects of an eruption.
Location and cause of earthquakes. Features
of earthquakes – epicentre, focus, shock
waves and the measurement of earthquakes
using the Richter and Mercalli Scales.
A case study of an earthquake in a rich part of
the world and one from a poorer area – their
specific causes; primary and secondary effects;
immediate and long term responses – the need
to predict, protect and prepare. Contrasts in
effects and responses will be clear.
A case study of a tsunami – its cause, effects
and responses.
Key Words:
Key word:
Core
Crust
Mantle
Oceanic Crust
Continental Crust
Plates
Convection currents
Destructive plate
Margin
Subduction Zone
Oceanic Trench
Constructive Plate
Margin
Conservative plate
Definition:
This is the name given to the centre
of the earth
This is the thin layer of cool rock
which we live on. There are two
types continental and oceanic
This is the mass of molten rock that
surrounds the core of the earth
Dense (heavy) and about 5 km thick
(heavier but lighter than continental
crust)
Light and 30 km or more thick
(lighter but thicker that oceanic
crust)
These are the names given to the
seven larger and many small sections
of the Earth’s crust
These are the hot currents within
the earth’s mantle
These are plates that move/ bang
together. One plate gets pushed
under the other where it gets
melted (destroyed) in the
subduction zone
Earthquakes take place here and
Composite volcanoes occur here.
Fold Mountains occur here
an area where one tectonic plate
(usually part of the ocean) is going
down under a second plate
a long and narrow depression along
the ocean bottom these occur at
subduction zones
These are plates that are moving
apart- as the move apart the gap is
filled with magma rising up
(constructing new land)
Shield volcanoes only are created
here
These are plates that slide by each
other.
Earthquakes only take place at
these margins
Example
Nazca plate
South American
plate
The boundary
between the Nazca
and South
American plates
Marianas Trench
The margin
between the North
American and
Eurasian plates
The boundary
between the North
American and the
pacific plates
Composite volcano
Created at destructive plate
margins
Tall
violent
Made of alternate layers of rock
and lava
Made with Acid lava- thicker
slow moving lava with a high
silica content
Etna in Italy
Landforms created at destructive
plate margins when plates push
sedimentary rock together forcing
it up into tall, jagged mountains
This is a huge depression on the
surface of the earth eg seas
Rock formed at the base of the sea
that is made of different layers of
sediment.
A simple upfold
A simple Downfold
 Created at constructive plate
margins
 Wide base with gentle slopes
 Regular frequent eruptions
 Made of lava only
 Made with basic lava- pours out
easily, is runny and flows a long
distance, has a low silica content.
A cone shaped mountain formed by
surface eruptions
a large underground pool of molten
rock found beneath the surface of
the Earth from which volcanoes are
formed because of eruptions
This is the name given to magma
when it reaches the earth’s surface
Molten (hot- liquid) rock in the
earth's crust
The passage in a volcanoes through
which the magma escapes
The Alps
The Andes
The Rockies
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Fold mountains
Geosynclines
Sedimentary rock
Anticlines
Synclines
Shield volcano
Volcano
Magma chamber
Lava
Magma
Vent
Vesuvius in Italy
Soufriere Hills
Volcano in
Montserrat
Mount Loa in Hawaii
Helka in Iceland
Shield, Composite
Crater
Basic lava
Acid lava
Supervolcano
Primary effect
Secondary effect
Natural hazard
Tiltmeter
Earthquake
This is the circular top of a volcano
through which lava, ash and gas gets
thrown out of a volcano
Lava found at constructive plate
margins. Come from within the
mantle and has a low silica content.
It pours out easily, is runny, and
flows long distances
Lava found at destructive plate
margins.
It has high silica content. It is
viscous (thick) so it travels shorter
distances before cooling- leads to
explosive volcanoes
A volcano that erupts with a massive Yellowstone super
volume of materials
volcano
The immediate impact of a natural
hazards eg
 People injured and hurt
 Buildings, property and farmland
destroyed
 Communications and public
services disrupted
The medium and long term impacts
of a natural hazard eg
 Shortage of drinking water, food
and shelter
 Spread of disease form
contaminated drinking water
 Economic problems from the
cost of rebuilding and the loss of
farmland factories tourism and
economic activities
 Social problems from families
losses and stress
Earthquakes, volcanic eruptions and
tsunamis
These measure very small change in
the profile of a mountain.
These are vibrations in the Earth’s
crust that shake the grounds
surface
Richter scale
Seismometer
Mercalli Scale
Focus
Shock waves
Epicentre
Responses
Tsunami
A value on the Richter scale (1-10);
A logarithmic scale used to express
the energy released by an
earthquake. The difference in
strength between a 6 and a 7 of the
Richter scale is 10 times.
The instrument used to measure the
magnitude of an earthquake
Used to indicate the intensity of an
earthquake. It is obtained by making
a judgement it is a scale I to XIII
The point at which the earthquake
happens below the ground surface.
The energy of an earthquake that
spreads out in all directions from an
earthquake, lasting from less than a
second to several minutes.
This is the point on the surface
directly above the focus of an
epicentre.
The action taken by people after a
disaster in the short-medium and
long term. Eg the police etc
A very large and destructive wave,
generally caused by a tremendous
disturbance in the ocean, such as an
undersea earthquake.
Indonesia and Asian
Tsunami 2004
At these margins 2 plates move together and the Destruction of some of the Earth's crust results. An
oceanic plate (denser) is pushed towards a continental plate (less dense) by convection currents deep
within the Earth's interior. The oceanic plate is subducted (pushed under) the continental plate at what is
called a subduction zone, creating a deep ocean trench. It is the Oceanic crust which sinks down into the
mantle because it is denser (heavier). As it descends friction, increasing pressure and heat from the mantle
melt the plate. Some of this molten material can work its way up through the continental crust through
fissures and cracks in the crust to collect in magma chambers. This is often some distance from the margin
where magma can eventually re-emerge at the surface to create a range of mountains. The movement of
the plates grinding past one another can create earthquakes, when one plate eventually slips past the
other releasing seismic energy. There are several really good examples of Destructive plate margins,
including along the West coast of the Americas and Japan, where the Philippines sea plate is pushed under
the Eurasian plate.
At these type of plate margins two plates are moving apart from each other in opposite
directions. Convection currents moving in opposite directions (caused by the intense heat of
the Earth's interior) in the mantle move two plates apart. As these plates move apart this
leaves cracks and lines of weakness, that allows magma from the mantle to escapes from the
highly pressurised interior of the planet. This magma fills the gap and eventually erupts onto
the surface and cools as new land. this can create huge ridges of undersea mountains and
volcanoes such as the Mid-Atlantic Ridge, and where these mountains poke above the level of
the sea islands are created. Generally volcanoes result at these margins. A really good example
of this is the mid Atlantic Ridge, where the Eurasian plate moves away from the North
American plate at a rate of around 4cm per year. Iceland owes its existence to this ridge.
At conservative margins mountains are not made,
volcanic eruptions do not happen and crust is not
destroyed. Instead, 2 plats either slide past each
other in opposite directions, or 2 plates slide past
each other at different speeds. As they move past
each other friction builds as the plates snag and
grind on one another. When this friction is
eventually released it sends shock waves through
the earth’s crust. We know these shock waves as
earthquakes, and a good example of this is the
San Andreas fault in California, where the Pacific
plate is moving NW at a faster rate than the North
American plate.
Fold mountains form along
destructive plate. As the plates
are pushed together, the sediment
that has formed in the seas
between them is compressed and
pushed upwards, as seen opposite.
Creating the Alps, Andes, Rockies
and the Himalayas.
Our Case study involves the Alps
and these were formed 30-40
million years ago. They are located
in central Europe and are found in
France, Italy, Austria, Germany
and Switzerland. The Alps consist
of many high mountains such as Mt.
Blanc, the Matterhorn and Eiger.
This is also where Europe's great
rivers begin such as the Rhine,
Rhone and Danube. Finally it is also
where some of the largest lakes in
Europe are located such as Lake
Garda, Geneva and Como.
The main features of this
region are the U - shaped valleys,
glaciers and the snow especially in
the winters. See opposite.
The Majority of Ocean trenches are located
around the sides of the Pacific Ocean at
DESTRUCTIVE PLATE MARGINS.
The subduction zone is an ocean trench . One
wall is formed by subducted ocean plate and
the other by the overriding Continental plate.
These are very deep usually around 500010,000 metres deep
Ocean trenches are inaccessible to humans.
CASE
STUDY
CASE
STUDY
Farming
Tourism
HEP & Industry
The valley floor is ideal for
The Alps are an ideal
Tourism is one of the
location for the production
biggest growing industries in
of HEP as there are steep
the Alps (see DVD on
slopes to produce fast
Livigno). Over 20 million
flowing streams. The area
people visit the Alps every
has high rainfall and of
year and the main reasons
course the snow melts in the
are as follows:
spring/summer. Finally the
* Beautiful winter scenery
The traditional type of farming
narrow valleys are easy to
with snow capped peaks and
was known as Transhumance. This
dam. As a result the
forests
electricity produced is
* Winter sports resorts for
usually very cheap and this
skiing, skating and
attracts industries who rely
tobogganing
over winter and fed on the straw
on the cheap energy.
* Summer lake resorts such
that had been grown on the valley
The main industry in the
as at Lake Como, Lake Garda
region is forestry which
and Lake Geneva
relies on the conifers for
Excellent communications
building purposes, paper, fuel
which includes motorways,
and even for cuckoo clocks.
railways and airports.
farming and the main type is
usually is Dairy Farming although
vineyards can be found in warmer
areas. It is ideal here because:
* The land is flatter
* The soils are deeper and more
fertile
* There are better
communications
was where the cows were taken up
on to the Alps in summer after the
snow had melted and returned in
the Autumn to be kept in barns
floor. This type of farming is rare
now as much of the valley floor is
taken up with villages and skiresorts which are far more
profitable.
Tunnels have been built to
The Problems of Alpine Valleys
Few people live in Alpine areas for a number of reasons:
* Poor communications due to the mountains
* Few industries are attracted so there are few jobs
* High altitude areas with cold wet climates
* Avalanches and landslides are dangerous and can cause
problems
* Farming is difficult due to the steep slopes and short
growing season
access ski resorts such as
Livigno
* The alpine climate have
attracted many for the snow
and clean dry air, especially
those with breathing
problems.
SHIELD VOLCANOES
Composite Cone Volcanoes
Formed at DESTRUCTIVE PLATE MARGINS
Formed at CONSTRUCTIVE PLATE MARGINS
As the plates move apart magma rises upwards
from the mantle to fill the gap.
This adds new rock to the spreading plates.
Some of the magma may also be forced out to the
surface through a vent. Some volcanoes grow high
enough to form volcanic islands.
Characteristics of a Shield volcano
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Cone with wide base and gentle slopes
Made of lava only
Regular and frequent eruptions
Lava pours out with little violence
Examples
When the plates collide, the denser oceanic plate
is pushed down into the mantle. Here the plate
melts and is destroyed in the subduction zone. In
the subduction zone the plate forms a pool of
magma. The great heat and pressure may force
the magma along a crack where it erupts at the
surface to build up a volcano
Characteristics of a Composite Cone Volcano
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Tall cones with narrow base and steep
sides
Made of alternate layers of lava and ash
Irregular with long dormant periods
Violent explosions possible
Hekla and Surtsey in Iceland
Examples
Etna, Vesuvius and Stromboli in Italy
Mauna Loa and Kilauea in Hawaii
Krakatoa in Indonesia
A supervolcano is a volcano that erupts with a massive volume of material- much more than a
normal volcano- at least 1000km3 of magma. (volcanoes can give off 1km3 of magma)
A supervolcanic eruption alters the landscape over 100s or even 1000s of Kms. So much dust is
circulating that it can lead to a ‘volcanic winter’ this means that cooler temps occur on Earth
because less sunlight reaches the surface.
Supervolcanoes are very large volcanoes that they can only be identified from space/air
they do not have a cone shape they form a dome. An example is Yellowstone in the USA
Volcanic eruptions and Earthquakes have both primary and secondary effects
Primary effects= immediate effects
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People injured and killed
Buildings, property, and farmland destroyed
Communications and public services (transport, electricity, telephones etc.)
disrupted
Secondary effects= the medium and long term impacts
 Shortage of drinking water, food and shelter
 Spread of disease from contaminated water
 Economic problems from the cost of rebuilding and the loss of farmland,
factories, tourism and other economic activities
 Social problems from family losses and stress.
WHY DO PEOPLE LIVE NEAR
VOLCANOES?
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After lava has weathered it is
some of the most fertile soil in
the world
Volcanic areas attract tourists eg
bathing, walking
Hot water can be used to
generate electricity
Valuable minerals
EG CAMPANIA near Vesuvius in
Italy
Can volcanic eruptions be predicted?
Yes and No
Some warning signs such as
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small earthquakes
increases emissions of steam and gases
visual signs of bulging around the crater
Volcanoes near populations are constantly monitored.
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Electric Tiltmeters measure small changes in
the profiles of mountains- like a sprit level
Satellite are used to measure infra red data
because of the danger involved
Poorer countries do not have the same ability to
monitor volcanic activity
Volcanoes are very hard to predict
How are Earthquakes measured?
Richter Scale.
The magnitude of an earthquake is
measured by an instrument known
as a seismograph and given a value
between 1 and 10.
It is logarithmic an earthquake
measured at 7 is 10 times stronger
than a 6 and 100 time stronger than
a 5.
Mercalli Scale.
Is used to indicate the intensity of
an earthquake.
It classifies the effects of an
earthquake on a scale using roman
numerals I to XII. It takes into
account the effects on the Earth’s
surface, buildings and people
Effects of Earthquakes
Primary effects include
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Collapsed bridges, roads, buildings.
People killed or trapped.
Secondary effects include
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Fires are caused by broken gas pipes and collapsed power
lines.
Tsunamis
Landslides
Diseases such as typhoid and cholera
Often more severe in poorer countries where earthquake
resistant buildings are considered too expensive. Building
regulations are often ignored. People and authorities are often
not well prepared
The Responses to Earthquakes.
In poor and rich countries immediate
emergency is needed everywhere. In rich
countries-Specialist rescue teams with sniffer
dogs and lifting equipment and medical
teams with field equipment can be air lifted
quickly into the area.
Poor countries often rely on short term aid
from abroad.
Medium term need to rebuild and return to
normal life- repairing/ replacing what has
been lost and restarting economic activity.switch from disaster aid to development aid.
Long term is to be prepared- trained
emergency services. Earthquake proof
buildings.
The Indonesia and Asian tsunami, Boxing day 2004
Information
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Speed 500 km/h
CASE
Highest recorded wave 34m
Distance travelled from epicentre 4000km
STUDY
Number of people dead or missing 220,000+
Number of people displaced about 2 million
House destroyed Over 500,000
Measure on Richter Scale 8.9
Indo-Australian plate pushed under the Eurasian plate
Fifth strongest earthquake ever recorded
Within 4 hours many populated areas of Thailand, Indonesia, India and Sri Lanka are left in ruins
Human Responses to the disaster
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Within a week £450 million had been pledged from around the World
Worlds biggest emergency relief operation began immediaetey
Cargo planes from around world brought blankets and medicines
Trucks being food, medicines and body bags reached areas accessible by road
Air drops to coastal areas cut off provide relief
Troops used bulldozers helped to clear dead bodies into mass graves to reduce the risk of disease
International tsunami warning system between countries were set up.
California, USA Earthquake 2003
Bam, Iran Earthquake in 2003
Occurred on 22nd December 2003
Occurred on 26th December 2003
6.6 on the Richter Scale
25,000 people dead
6.5 on the Richter scale
CASE
STUDY
Why did it happen?
3 people dead
CASE
STUDY
Why did it happen?
Movement of three plates the Arabian
plate, the Asian plate and the central
Iranian block. A sudden movement
along these margins lead to the quake
Movement along the San Andreas fault. This
is located between the Pacific plate and the
North American Plate. A sudden movement
along this Conservative margin lead to the
quake.
Why was the Earthquake so
devastating?
Why was the Earthquake NOT so
devastating?
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The houses were build out of
poor quality materials, mud
brick, which collapsed straight
away
Mud brick disintegrates when it
collapses
When this happens it leaves less
air pockets. Air pockets give
people a chance of surviving
even when they are trapped.
Occurred at 5AM on a Friday,
Friday is the Muslim day of rest
so most people were at home
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The three people died because a
historic clock tower (Acorn
Building) collapsed. This was made
of wood and un-reinforced masonry
(brick)
Within 12 hours search and rescue
found all the victims
75,000 homes and businesses lost
power but service was soon restored
Minor damage could be repaired due
to payments from insurance
companies.
Building are designed to not crumble
even if they do collapse
Other things to consider:
Other things to consider:
Quality of services available
Quality of services available
Quality of preparation
Quality of preparation
Lack of early warning system
Early warning system