Natural Hazards

  • Created by: efrench
  • Created on: 27-05-15 09:03

Living with Natural Hazards

Earthquakes and Volcanoes

Primary and Secondary Effects


  • April 2010
  • North American Plate and Eurasian Plate moving away from eachother- constructive
  • ash cloud rose 11,000m into air
  • lava flows
  • melted 150m thick ice cap = major flooding
  • ash filled rivers = blockaging
  • 20 farms destroyed from ash = costly
  • Airspace closed across Europe - 17,000 flights cancelled a day
  • cost airlines $2 billion
  • £102 lost in London from tourist income
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The Effects of Earthquakes and Volcanoes


  • South Colombia, 400km from the West Coast -- 2006
  • 10km ash cloud into sky
  • huge lava flows
  • up to 5cm of ash
  • pyroclasric flows raced down slopes - destroyed 7 villages and 5,000 people homeless.
  • 6 died
  • hot ash = breathing difficulties
  • lava and ash covered fertile farmlands & ruined crops and livestock
  • roads impassable, local airports closed


  • 6,000 died and 37,000 injuried
  • 154,000 homes destoyed, leaving 1.5 million homeless
  • aftershocks 
  • business ruined and loss of income
  • Hindu Temple badly damaged
  • Overall damage - US$3 billion
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The Causes of Earthquakes and Volcanoes


  • plates move away from eachother & magma rises
  • volcanoes gently erupt all the time
  • small earthquakes from friction between mantle and moving plate
  • type of crust does not matter


  • two plates hit eachother and fold mountains form. Varied sized earthquakes form
  • need the Same type of crust


  • two plates move alongside eachother & create large earthquakes
  • type of crust does not matter


  • oceanic plate sinks underneath the less dense continental plate. Oceanic plate melts at bottom = volcano!
  • sudden movement of the plate releases this pressure and causes earthquakes
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Living with Tectonic Hazards

Why live in Volcanic areas?

  • Geothermal Energy - hot rocks below ground heats water to create steam which dives turbines. Provides 70% of energy need in New Zealand
  • Tourism - volcanic landscapes with beautifuk scenery. Jobs from tourist attractions
  • Fertile Soils - volcanic rocks are rich in minerals and when whethered, form fertile soils = ideal for growing crops
  • Raw Materials - raw materials for many products come from volcanoes
  • Mineral Extraction - valuble minerals can be extracted when volcanic activity occurs

Composite Volcanoes

  • lava is acidic
  • created along destructive plate margins
  • lava is viscous so creates steep mountains

Shield Volcanoes

  • lava is basic
  • occur along constructive plate margins.
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Kashmir Case Study - 2005

  • Indian Plate and Eurasian Plate colliding. Mountainous area on the boarder of India


  • 79,000 killed, 100,000 injured
  • building collapsed 
  • millions of homes destroyed
  • diseases spread - contaminated water
  • harsh winter = people died and only harsh tents to live
  • loss of jobs
  • schools and books damaged
  • overal cost $5 billion


  • military helicopters take injured and military hospitals opened
  • food and supplies carried from other countries for free
  • Red-Cross built water supplies
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LA Case Study

  • conservative plate boundary
  • 1994


  • 9 bridges collapsed
  • 7 killed
  • motorists trapped under rubble
  • landslides moves homes down slopes
  • 12,500 buildings damaged


  • all schools re-opened after a week
  • electricity supplies repaired within hours
  • 80,000 new housing units built
  • food handed out by popular stadium
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Monsterrat Case Study - 1995

  • North and South American plates being subducted under the Caribbean plate
  • August 1995 people evacuated North of Monsterrat
  • April 1996 - everyone forced to leave capital city of Plymouth
  • 1997 - south of island covered in hot ash
  • 2005 - south of island out of bounds. Population has increased to over 8000
  • present day - volcano is still erupting. People are re-building from damage
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Mount St Helens

  • Western Northern America, Washington

The Eruption

  • Pyroclastic Flows - 7000 animals kiled. 61 died. 
  • Ash Cloud - ruined crops and farming machinery. cost was $175 billion. Made roads unstable
  • Shape of Mountain - top was blocked by old solidified lava. After eruption - side had blown out and the top had collapsed
  • Landslides - snow at the top melted and caused mudslides. They flowed down river alleys at 35m per second.

Long Term Effects

  • US Government gave $951 million in aid to rebuilt industry in area
  • area now tourist attracton - local economy wealthier than before
  • increased risk of flooding due to new landscape
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Reducing the Effects of Earthquakes

How might we prepare?

  • Earthquake shaking maps
  • Education
  • Building codes -strict building regulations
  • Earthquake proof builidings
  • 'Appropriate Technology'
  • Retrofitting - addings things to old buildings to make it earthquake resistant

Bamboo homes in Costa Rica was 'appropriate technology' 

Earthquake Proof Buildings

  • roof weights to counter shock waves
  • Cross bracing to give added strength
  • Automatic window shutters to prevent falling glass
  • Automatic sprinkler system to prevent fires
  • rubber shock absorbers
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Reducing the Effects of Volcanoes

How might we prepare?

  • Emergency kits
  • volcanic hazard maps
  • restriciting access and evacuaiton
  • monitoring of volcano
  • improved building design

Evacuation in Java, Indonesia Case Study: EVACUATION

  • evacuation on May 2006 from the volcano they called Mount Merapi
  • Orange Code - Children and elderly women taken to emergency shelters
  • Red Code (highest level) - village people forced to leave 


  • bulldozers built earth and rock walls to direct lava away from villages
  • planes and helicopters dropped cold water to cool and slow down the lava flow
  • in the past - lava diverted away by using military bombing and dynamite 
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Reducing the Effects of Volcanoes

Sloping Roofs - ash slides off instead of collapsing home

Air Filter systems - stop ash coming into homes

Plastic Roof coverings - ash wont be able to corrode the roof

Sealing doors and windows - ash particles cant get in 

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What Causes Tropical Storms?

They form where the sea surface temperatures are over 27oC and form between 10o and 30o North and South of the equator.

How do they form?

  • several thunderstorms drift over warm seas
  • the warm air from the sea surface combines with the thunderstorms and warm air begins to rise
  • more warm air rises, and due to the Earth's rotations, starts to move in a spiral. It cools an condenses forming clouds, releasing much energy.
  • the air starts to rise faster and cooler air is sucked downwards. Windspeed starts to increase.
  • the tropical storm drifts over the ocean, picking up warm moist air. Cold air is drawn into the eye.
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Reducing the Damage from Tropical Storms

Forecast -- Prepare -- Act


  • can be accessed on internet. Regularly updated.
  • includes an area of uncertainty, where the hurricane may strike within a 3-day or 5-day period.
  • people who live within the area should prepare 
  • they also show, wind speed, current centre location, day and what time, predicted path


  • education programmes for how to respond
  • school lessons, posters leaflets giving advice on drawing up a family disaster plan, putting together an emergency kit and simple methods of protecting their homes
  • tropical storms are closely monitored by angencies like the Nation Hurricane Centre

How can LEDC's prepare?

  • training locals in how to organise others in evacuation
  • educating women on what to wear incase they need to swim
  • building homes on stilts and cyclone shelters
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Effects of Tropical Storms


  • damage to buildings
  • roads and infrastucture damaged
  • loss of animal habitats 
  • sea fish killed


  • trauma and stress
  • water-borne diseases
  • job losses due to damage to industries
  • food and water shortages


  • repair and insurance claims
  • loss of income from closed business
  • crops destroyed
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Hurricane Case Study

Hurricane Hanna

  • 550 died
  • City of Gonaives badly damaged
  • tin-roofed homes across country destroyed
  • leaving 1 millions people homeless
  • Much of low-lying Gonaives was flooded
  • roads impassable
  • - other parts of Haiti - whole villages buried under mudslides
  • - little natural defence from mud slides due to forests being removed
  • - crops destroyed along with cows and goats
  • - people left with no food or income

What did they do?

  • United Nations troops has to supervise food aid distribution
  • three days later, another hurricane hit Haiti taking 74 more lives and worsening the food crisis
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More Tropical Storms to come?

  • many people think climate change from global warming has increased the number of storms
  • other believe that it has stayed the same
  • scientists say it will start to decline in the future

Why are opinions divided?

  • satellite technology has only been used to monitor since the late 1960's
  • before -- accounts from ships' logs, aeroplane reseach flights and simple weather recording instruments were used
  • scientists beliveed that the strenght of the storms were greater than what was actually recorded at the time
  • there is a natural cycle of variations in the number of hurricanes
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More Tropical Storms to come?


  • number of tropical storms has doubled in the last 100 years
  • since 1995, they have become more frequent and more intense
  • due to global warming, sea surfaces have risen by 0.5 oC in the last few decades

Stays the Same

  • do not have enough evidence linking global warming to changes in the number of tropical storms
  • short term changed to the number of tropical storms may not be due to the actions of people
  • changes to the number of tropical storms
  • the changes are part of a natural cycle


  • technology predicts that the number of tropical storms will fall after 2080
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The Causes of Wildfires

Natural Causes

  • lightening
  • spontaneous heating
  • volcanic eruptions
  • hot, dry weather
  • droughts
  • Santa Ana Winds 
  • South facing slopes - sun dries out vegetation

Human Causes

  • accidents
  • broken bottles act as magnifier
  • slash and burn - method used by farmers to clear land to grow crops
  • arson
  • sparks, chimneys, BBQ's

Combo of both!!!

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The Effects of Wildfires

California Wildfires Case Study: 2007

  • destroyed over 200,000 hectares of grassland and woodland
  • 640,000 people had to evacuate their homes
  • 9 died, 85 injured
  • over 1,800 homes destroyed
  • damage cost US $1.6 billion.
  • trauma from seeing loss of homes
  • clouds of smoke blotted out the sun and raised levels of air polltuon to three times the normal level
  • caused breathing problems
  • business and factories had to close
  • distrupted important trade
  • farms and crops damaged and dead
  • many species of animals killed in teh blaze
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Other Wildfire Case Studies

Colorado - 2012

  • extremely dry winter before
  • arsonists
  • dry thunderstorms

Laguna Fire, California - 1970

  • started by downed power lines
  • during Santa Ana winds 

Tasmanian Fires, Australia - 1967

  • had its driest 8 motnh period since 1885.
  • several bushfires from extremely dry and hot weather
  • some were caused by deliberate burning
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How can Wildfires be reduced?

Responses to wildfires

  • public educated on how they start
  • fire line/ fire breaks
  • removing dead leaves and branches
  • backfires
  • public advised to have a family evacuation plan
  • wildfire risk map
  • people evacuated
  • given advice on burning things to reduce sparks
  • air drops: released from aircraft onto fire
  • areas sprayed ahead of fire to stop from spreading

Smokey Bear Case Study

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More Wildfires to Come?

  • Climate change has an effect on the number of wildfires
  • other scientists feel that periods of increased wildfires are part of a natural cycle where there are periods of higher temps and lower rainfall.

Calfornia Wildfires due to Climate Change Case Study

  • vegetation grew heavier than normal and tehn ignites during long draughts
  • parts of the United States may experience several wet years followed by several drier than normal
  • during these periods, wildfires can spread very quickly
  • droughts or heat waves would lead to wildfires larger than ever before

Climate Change could lead to more and larger wildfires

  • researchers say - the are burned by wildfires could double by teh end of teh century of the climate warms
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