Earthquakes

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Earthquakes

Causes:

  • At plate boundaries 
  • Nucleur testing 
  • Drilling for oil 
  • Coal mining

Focus: The place where pressure is released by a sudden jerk in the earths crust.

Epicentre: The point on the earths surface immediately abouve the focus where the destructive effects of the earthquake are greatest 

  • Measured using Seismometers
  • Measured on The richter scale: 1 = micro and 9 =devastateing 

Physical Consequences of earthquakes:

  • Liqification
  • Tsunami
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Case Study: Kobe Earthquake

Kobe= MEDC in Japan (Jan 1995)

Epicentre: 20km south west of Kobe

Boundary Type: Destructive 

Cause By: Philline(oceanic plate) going under Eurasian (Continental plate)

Duration: 20 seconds 

Depth: 16km

Strength: 7.2

Impacts, Short term: 

  • Over 40,000 people injured
  • Arounf 5,500 died
  • 300,000 homes destroyed
  • almost all economic activity stopped 
  • fires rafed through Kobe for days, destroying around 7,500 homes
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Kobe Earthquake: Impacts

Short term impacts on people: 

  • Over 40,000 people injured
  • Arounf 5,500 died
  • 300,000 homes destroyed
  • almost all economic activity stopped 
  • Transport routes disrupted

Short Term impacts on the Enviroment

  • Liquification- turning solid ground into mud.
  • Almost all economic activity stopped
  • More than 150 fires raged through Kobe for several days, destroying around 7500 homes.  The fires released smoke into the air, creating smog.
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Kobe Earthquake: Long term Impacts

Long term Impacts on People:

  • Over 5500 died
  • Took several months for electricty, water and gas supplies to be restored
  • 90% of Kobe port was severly damaged 
  • Traffic congestion was not just short term, but continued for a considerable amount of time
  • Took long time to rebuild houses 

Long term impacts on Enviroment:

  • Cracks or 'faults' were observed.
  • A lanslide changed the shpae of fields
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Kobe Earthquake: Response

Precautions:

  • September 1st - public holiday - practise drills
  • Revised building code
  • Many arrangements with fire departement - fire staff training

Immediate strategies:

  • Short term shelters- food and water- 1100 set up
  • Emergencie budget- $100 billion Us dollas 

Long term Strategie:

  • Smart systems for gas and water 
  • Fire department hoses 100ml instead of 65ml
  • Revised 1981 building code- stricter on structures 
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Case Study: Indonesia Earthquake

Indonesia Earthquake, LEDC (Dec 2004)

Strength: 9.0

Duration: 3-4 minutes

Depth: 30km

Boundary type: Destructive 

Plate: Indo-Australien plate and Burma micro plate

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Indonesia Earthquake: Short term Impacts

Short term implacts on people:

  • Problems with foods supply and loss of utensils 
  • People injured and looking for fam member - large displaced population
  • Many died
  • 92000 farms and small buisnesses destroyed - many lost their livlihoods
  • Houses damaged, lack of shelter 
  • Pressure on medical service tp treat the injured 
  • Bodies had to be disposed of quickly to prevent diseases spreading 

Short term impacts on Enviroment:

  • Whole earth vibrated by 1cm
  • tsunami hit heights of 10m
  • After shocks caused region to shake for another 3-4 months
  • Loss of livestock and rice growing areas
  • Freshwater soures destroyed or contaminated 
  • Loss of trees 
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Indonesia Earthquake: Long term impacts

Long term impacts on People:

  • Political impact- peace as result- rebel group declared cease fire
  • psychological impact on children 
  • many young people now growing up without parents 
  • Schools closed or struggled to stay open 
  • Houses rebuilt to higher standard, improved facilities for survivors 

Long term impacts on Enviroment:

  • Raising of sea bed reduced capacity of indian ocean, raised global sea level by 0.1mm
  • Coastal ecosystems damaged
  • release of energy shortened length of a day by 2.68 microseconds
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Indonesia Earthquake: Response

Precautions: (beofre earthquake)

  • no tsunami monitioring/ warning systems 
  • No earthquake education or practise days
  • No building control
  • No rescure equipment 

Immediate strategies:

  • Indonesian gov. launch appeal for aid- largest reponse to natural diaster in history
  • Assesment of damage
  • Cash for worl fpr those who had lost jobs, families etc.
  • Temporary infrastructure- as powerlines, bridge roads etc damaged 
  • Restocking of backyard poultry 

After strategies:

  • Network of tsunami warning buoys laid in Indian ocean 
  • Warning sierins installed in coastal regions 
  • Organisations such as red cross introduced education and prepardness training.
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Summary diagram of plate boundaries

Plate Margin

Direction of movement

Examples of plates

Crust tyre

Type of activity

Features

Destructive



Eurasian plate  and Philippine plate

Continental and oceanic

Earthquakes and volcanic eruptions

Trench,

Fold mountains

Constructive

Eurasian and N. American plates

Oceanic and oceanic

Earthquake and volcanic eruption

Mid-Atlantic ridge and volcanoes

Collision



Continental and continental

Earthquakes

Fold mountains e.g. Himalayas

Conservative



San Andreas fault

Earthquake

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Volcanoes

Volcanoes are mountains, often cone shaped, formed by surface euruptions of magma from inside earth.  

  • Most vocanic activity in the 'ring of fire'

At Constructive Plate Margin

  • Plates move apart
  • Magma wells up from the mantle to plug the gap = volcanic activity
  • This rising of material causes the crust to rise slightly at either side of plate margin creating a mid-Atlantic ridge.
  • Volcanoes found along this ridge are called smokers 
  • The hardened lava erupted from volcano forms new crust. 
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Volcanoes

Destructive Plate boundaries

Example: Nazca Plate (oceanic) and South American plate 

  • Pressure builds up over many years 
  • Once pressure is released the two places with jolf ---- Makeing EARTHQUAKE 
  • As Nazca plate is subducted it begins to melt due to heat.
  • Magma is created
  • It rises up wards as an explosive magma. 
  • If it breaks through surface it creates a volcano
  • The continental Sounth american plate is not subducted easily 
  • Instead it folds and buckles upwards to creeate a liear fold mountain
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