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GCSE Revision session.

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GCSE Revision session. Tectonic activity With Mr Thompson. Introduction. Paper 1 Physical Geography. Make sure you know key terms Make sure you know: features, how ... – PowerPoint PPT presentation

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Title: GCSE Revision session.


1
GCSE Revision session.
  • Tectonic activity
  • With Mr Thompson.

2
Introduction.
  • Paper 1 Physical Geography.
  • Make sure you know key terms
  • Make sure you know
  • features,
  • how they are formed,
  • the effect they cause,
  • advantages and disadvantages to human life.
  • Human responses and that you can relate it to
    actual places.

3
  • This unit can be split into 3 sections. Often one
    will affects another. They are
  • The earths structure.
  • Volcanoes
  • Earthquakes.

4
The Earths structure.
  • Activity 1 on the earths outline label on the
    following
  • Mantle
  • Outer core
  • Inner core
  • Crust
  • Mantle
  • Plates

5
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6
  • The CRUST is made up of interlocking slabs of
    rock called PLATES which are moving and float on
    the MANTLE. They can be CONTINENTAL or OCEANIC

7
  • OCEANIC CRUST - Under the oceans, Dense (heavy),
    thin and gets destroyed at SUBDUCTION ZONES and
    created at CONSTRUCTIVE BOUNDARIES.
  • CONTINENTAL CRUST - Under the continents,
    lighter, thicker and permanent.

8
  • PLATE MOVEMENT - caused by CONVECTION CURRENTS in
    the MANTLE.
  • PLATE BOUNDARY - Where two plates meet. Most of
    the world's EARTHQUAKES and VOLCANOES are found
    on plate boundaries.

9
TYPES OF PLATE BOUNDARY
  • COMPRESSIONAL . Where two plates move towards
    each other. Two types-
  • DESTRUCTIVE - Where oceanic crust moves towards
    continental crust and is destroyed at the
    Subduction Zone. Earthquakes and Volcanoes are
    violent and Fold Mountains are found eg West
    coast of South America where Nazca plate meets
    South American plate.

10
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11
COLLISION
  • Where two Continental plates collide. Fold
    Mountains are formed. There are earthquakes, but
    no volcanoes. Eg Himalaya's

12
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13
TENSIONAL or CONSTRUCTIVE
  • Where two oceanic plates move apart and new crust
    is formed. The earthquakes and volcanoes are more
    gentle. Can create a mid-ocean ridge eg The Mid
    Atlantic Ridge.

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15
CONSERVATIVE
  • Where two plates slide past each other. Friction
    between the plates can cause pressure to build up
    that can lead to violent earthquakes when it is
    released. Eg San Andreas Fault.

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17
WHAT CAUSES FOLD MOUNTAINS TO BE FORMED?
  • Convection currents cause two plates to move
    towards each other.
  • Pressure causes a large downfold called a
    GEOSYNCLINE.
  • Erosion leads to sediments being deposited in
    the geosyncline.
  • Sediments build up and are compressed.
  • Pressure from the moving plates cause the
    sediments to fold.
  • As movements get more violent fold mountains are
    formed.

18
Step 2.
Step 1.
Step 1
Step 4
Step 3.
Step 5
Step 6
19
HOW DO FOLD MOUNTAINS INFLUENCE HUMAN ACTIVITY?
  • ADVANTAGES
  • Income from tourism eg skiing in winter and hill
    walking/climbing/mountain biking in summer.
  • Hotels, Bed Breakfast, Campsites.
  • Pleasant environment to live in.
  • Employment in farming, forrestry HEPGrowth in
    tourism reduces out migration.

20
DISADVANTAGES
  • Tourism can cause increase in traffic, buildings
    which spoil the scenery, increase in house
    prices, pollution and footpath erosion.
  • Difficult communications, often remote areas.
  • Lack of industry for alternative employment.
  • Wildlife affected

21
Volcanic eruptions
22
WHAT CAUSES A VOLCANIC ERUPTION?
  • OCEANIC crust moves towards CONTINENTAL crust.
  • The OCEANIC crust is forced under the
    CONTINENTAL CRUST
  • Friction and heat from the mantle melts the
    OCEANIC crust
  • MAGMA is forced upwards through weak points in
    the rock.
  • Pressure build up leading to violent volcanic
    eruptions.

23
Activity 2.
  • Draw and lable the STRUCTURE OF A VOLCANO with
    the following
  • CRATER
  • ASH, BOMBS GASSES, (PYROCLASTS)
  • LAVA FLOW
  • MAIN VENT
  • LAYERS OF ASH AND LAVA
  • SECONDARY OR PARASITIC CONE
  • DYKE
  • EARTH'S CRUST
  • MAGMA CHAMBER

24
Main Vent
Crater
Ah, bombs and gases (Pyroclasts
Lava flow
Secondary or parasitic cone
Dyke
Earths crust
Layers of ash and lava
Magma chamber
25
Key Phrases.
  • ACTIVE VOLCANO - Erupts regularly or recently eg
    Stromboli, Montserrat, Mt. St. Helens or Mt.
    Pinatubo.
  • DORMANT - Has not erupted for a long time (about
    2000 years)
  • EXTINCT - Volcano that no longer erupts
  • MAGMA - Molten rock that becomes LAVA when it
    reaches the surface of the earth.
  • NUEE ARDENTE - A volcanic cloud of gas, steam and
    ash. E.g. eruption of Mt. St. Helens, Mt Etna or
    Montserrat.

26
WHY ARE VOLCANOES DIFFERENT SHAPES?
  • STEEP SIDES - Due to the lava being VISCOUS
    (thick). This lava is also known as ACID lava and
    is rich in SILICA. They are found on DESTRUCTIVE
    Plate Boundaries eg VESUVIUS. ASH volcanoes are
    also steep sided. COMPOSITE (a mixture of ash and
    lava)

27
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28
GENTLE SIDES
  • Lava is NON-VISCOUS (runny) or BASIC. They are
    called SHIELD volcanoes eg MAUNA LOA (HAWAII).
    They are found on CONSTRUCTIVE Plate Boundaries.
    They are less explosive.

29
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30
A CALDERA
  • A large crater caused by the top of a volcano
    being blown off or the cone collapsing into the
    VENT eg CRATER LAKE, USA.

31
EFFECTS OF VOLCANOES
  • SHORT TERM
  • Ash falls on nearby farmland villages and towns.
    Torrential rain LAHARS and MUDFLOWS (water
    picks up huge amounts of ash).
  • Ash can cause buildings to collapse eg houses,
    factories, schools hospitals.
  • Lava can destroy anything in its path.
  • Eruption can kill people close to the volcano.
  • Roads and bridges become impassable.
  • Power suppies cut off
  • Water supplies contaminated

32
  • LONG TERM
  • Crops destroyed by ash and lava and prevented new
    crops being planted.
  • People forced to move away to other towns and
    cities often into shanty towns.
  • People evacuated to refugee camps where diseases
    can spread very quickly.
  • Farm animals killed.
  • There can be long term effects on the climate eg
    delay global warming.

33
WHY DO PEOPLE LIVE NEAR VOLCANOES?
  • FERTILE SOIL - Volcanic ash eventually breaks
    down to form very fertile soil eg rice grown
    around Mt. Pinatubo and Vineyards Orange groves
    around Mt. Etna.

34
  • TOURISM - Potential income from people watching
    eruptions (eg Stromboli) or visiting dormant and
    extinct volcanoes.
  • GEOTHERMAL POWER - Countries like Iceland can
    generate most of the power they need through
    geothermal energy.
  • Other reasons
  • People do not realise the risk of an eruption.
  • In many LEDC's land is in short supply - it may
    be the only available land.
  • Scientists or Vulcanologists carrying out
    research on volcanoes

35
Earthquakes.
36
Key words.
  • FOCUS - Point in the earth's crust where the
    earthquake starts.
  • EPICENTRE - Point directly above the focus on the
    surface of the earth where the damage is
    greatest.
  • SEISMOGRAPH - Instrument that measures the
    strength of the shockwaves.
  • RICHTER SCALE - Scale used to measure an
    earthquake by the strength of its shockwaves.
  • MERCALI SCALE - A way of measuring the strength
    of an earthquake by the damage it does.
  • SHOCKWAVES -Movements in the earth's crust
    caused by the earthquake.
  • AFTERSHOCKS - Smaller shockwaves that follow the
    main earthquake.

37
EFFECTS OF EARTHQUAKES
  • SHORT TERM
  • People killed and injured.
  • Old buildings not built to withstand earthquakes
    collapsed.
  • People made homeless
  • Huge fires caused by broken gas pipes
  • Buildings weakened by original earthquake
    destroyed by aftershocks.
  • People die due to disease, shock and hypothermia
  • Liquefaction where ground becomes like quick
    sand.
  • Fire service unable to control fires due to lack
    of water caused by broken mains.

38
LONG TERM
  • Communication links destroyed
  • Employment lost due to destruction of factories
    e.g. Kobe 2 Toyota factories.
  • Kobe's port severely disrupted.Damage estimated
    to cost 80 billion
  • Areas still without services for periods of 12
    months and more.

39
HOW DO PEOPLE RESPOND TO EARTHQUAKES AND
VOLCANOES?
  • They build buildings that are strengthened with
    steel to withstand earthquakes. They are designed
    to sway.
  • They avoid building on clay and sand.
  • In Japan there are now monitors that will stop
    the railways, turn off the gas as soon as the
    primary waves are felt.
  • By mapping previous earthquakes and plotting the
    regularity of earthquakes it is possible to
    estimate when the next earthquake may strike.
  • By monitoring earth movements and gas emissions
    it is possible to forecast volcanic eruptions eg
    Mt. Pinatubo in the Phillipines.
  • Emergency planning eg in Japan where they hold a
    Disaster Day when everyone practices what to do
    if an earthquake strikes. There are simulators
    where people can experience an earthquake.
    Posters telling people what to do in an
    earthquake.

40
WHY ARE MORE PEOPLE LIKELY TO DIE IN LEDC's THAN
IN MEDC's?
  • Less medical and relief support available.
  • Poorer communications often mean that access to
    affected areas is more difficult.
  • Housing is often of poorer construction, more
    likely to collapse or catch fire.
  • Lack of money to provide instruments or
    technology to predict disasters or limit there
    effects.
  • Poorer medical and emergency services and lack
    of emergency equipment.
  • Many people in LEDC's are subsistence farmers
    and if their crops are destroyed they have
    nothing else.
  • Power and water supplies may be disrupted
    allowing disease to break out and spread quickly.

41
Case studies.
  • MEDCs Kobe Californa
  • LEDCs - Iran

Iran
42
Two earthquakes compared.
California
Iran
43
Location Bam in Iran
Date 26 December, 2003
Strength of earthquake on the Richter scale 6.6
Number dead 28,000
44
Location California in USA
Date 22 December, 2003
Strength of earthquake on the Richter scale 6.5
Number dead 28,000
45
Here are some other reasons why the earthquake in
Iran was so bad
  • The houses in Iraq were badly built. They were
    made from mud brick which collapsed straight
    away.
  • When mud brick collapses it disintegrates.
  • This leaves less air pockets, which might have
    allowed some people to survive, even though they
    were trapped.

46
The time of day when the earthquake happened was
also important. In Bam, it happened at 5 oclock
on a Friday morning. Friday is the Muslim day of
rest. Where do you think most people were, and
why did they die?
These are like the mud brick buildings that
collapsed in Bam
47
Buildings like this in a rich country might
topple, but they dont crumble. What would be
your chance of survival in this situation?
48
Other things to consider
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