the challenge of natural hazards

• what is a natural hazard and give both main types

  • a natural event causing damage to people/property.
  • geological and meteorological
• whats a natural disaster?

  a hazard that has happened
• what 5 factors affect the risk of natural hazards

  • vulnerability
  • wealth
  • type of hazard
  • frequency
  • magnitude
• how are tectonic hazards distributed

  found on plate margins;clustered around the edge of the pacific plate(Ring of Fire)

  
• layers of earth:

  • crust(solid rock)
  • mantle(molten rock, contains convections currents)
  • outer core(molten iron and nickel)
  • inner core(solid iron and nickel)
• types of crust;

  • oceanic;more dense,sinks
  • continental;less dense,doesnt sink
• what happens at contructive plate margins and what forms

  • plates pull apart (convection current)
  • volcanoes and earthquakes form
  • e.g iceland (mid-atlantic ridge;north american plate and eurasian plate pulling apart)
• what happens at destructive plate margins and what forms

  • plates push onto eachother(oceanic crust sinks under continental)
  • volcanoes, earthquakes and tsunamis form +fold mountains and ocean trenches
  • e.g Nazca plate subducted under south american plate
• what happens at conservative plate margins and what forms

  • plates push past eachother or move in same direction but different speeds
  • only earthquakes
  • e.g San Andreas fault line in California(north american plate+pacific plate sliding past eachother)
• what causes earthquakes?

  friction builds between plates; tension builds as plates move and energy is released which sends out shockwaves.
• what are some primary effects of earthquakes?

  • building collapse
  • deaths
  • injuries
  • infrastructure damaged
  • water/gas/electricity disrupted
  • communications down
• what are some secondary effects of earthquakes?

  • landslides
  • tsunamis
  • gas leaks
  • fires
  • disease
  • expensive repairs
• what are some immediate responses of earthquakes?

  • rescue people
  • set up shelters
  • send foreign aid
  • provide water/food
• what are some long term responses of earthquakes?

  • re-house people
  • build earthquake proof buildings
  • reconnect water and electricity
  • rebuild roads
  • educate people about earthquake drills
• what are some reasons to live near tectonic hazards?

  • tourism
  • farming(fertile soil)
  • reluctance to leave family/friends
  • optimism
  • confident of government support
• what are some ways of managing tectonic hazards through monitoring and predicting?

  • satellites(detect ground movement & heat changes)
  • seismometers(detect ground shaking)
  • escaping gas(may indicate volcano eruption)
• what are some ways of managing tectonic hazards through protecting?

  • earthquake proof buildings (deep foundations, shock absorbers)
• what are some ways of managing tectonic hazards through planning/preparing?

  • educate people(earthquake drills)
  • prepare emergency services
  • evacuation routes
• where are hadley cells located?

  equator to tropics
• where are ferrel cells located?

  tropics to mid-latitudes
• where are polar cells located?

  mid-latitudes to poles
• descending air causes high pressure(in cold environments) and rising air causes low pressure(in hot environments)
• a tropical storm is a very powerful spinning storm cloud. They move at speeds of at least 75mph and can be hundreds of miles wide.
• how are tropical storms categoried

  using the Saffir-Simpson Scale
• tropical storms have different names depending on their location. Hurricanes occur in the Atlantic ocean and east of the Pacific. Typhoons occur in the west of the Pacific. Cyclones occur in the Indian ocean and south of the Pacific.
• what conditions are needed for tropical storms to form?

  • warm oceans at 27 degrees Celsius or more
  • mainly form between Tropics of Cancer and Capricorn
  • sea must have a depth of at least 60m
  • strong surface winds(they spin and join storm clouds together)
  • heat and moisture
• the direction of tropical storms is determined by the Coriolis effect which means in the Northern hemisphere tropical storms moves anticlockwise and in the Southern hemisphere they move clockwise.
• how do tropical storms form?

  • warm moist air rises above oceans creating low pressure
  • the Coriolis effect causes air to spin upwards around the eye of the storm(calm centre)
  • as the vapour rises, it condenses to then power the tropical storm
  • cold air sinks through the eye so its dry and calm there without any cloud on either side of the eye is the eye wall(where the storms fastest)
  • the storm travels across the ocean by the prevailing wind. it continues moving over warm waters being powered by evaporation and condensation.
  • when the storm meets land its no longer fuelled by water
• how does climate change affect the frequency, distribution and intensity of tropical storms?

  • DISTRIBUTION: as oceans become warmer, the conditions for tropical storm formation may extend further north and south of the current hazard zone.
  • FREQUENCY: total frequency expected to remain the same or decrease. frequency of categories 4-5 expected to increase and 1-3 to decrease.
  • INTENSITY: scientists aren't sure however categories 4-5 of tropical storms have increased. expected to become 2-11% more intesne by 2100
• primary effects of tropical storms

  • destroyed infrastructure
  • flooding
  • drownings
  • injuries
  • transport damaged
• secondary effects of tropical storms

  • homelessness
  • disease spread
  • job losses
  • aid cant get through
• immediate responses for tropical storms

  • evacuation
  • temporary shelters
  • temporary food
  • foreign aid
• long term responses of tropical storms

  • repairing homes and businesses
  • improve flood defences
  • strengthen buildings
  • improve forecasting techniques
• how can monitoring reduce the effects of tropical storms

  • use satellites/radar to track storms
  • evacuate people
• how can protection reduce the effects of tropical storms

  • make buildings storm proof(reinforced doors/windows)
  • build houses on stilts
  • sea defences
• how can planning/preparing reduce effects of tropical storms

  • educate people to have action plans ready
  • build new developments away from risk areas
  • evacuation routes
• examples of UK weather hazards:

  • rain(frequent; prolonged rainfall with sudden downpours can lead to flooding)
  • wind(strong winds can damage properties)
  • snow and ice(less common; can cause injuries; damage to crops)
  • thunderstorms(common in summer; can cause fires)
  • drought and heat waves(dangerous to elderly; can damage road tarmac; hosepipe bans may happen)
• evidence for climate change over the years:

  • temperature records increased since 1860(short term)
  • ice sheets form every year that provide data about the temp that year(long term)
  • sediment cores provide temp data based on trapped organisms(long term)
  • ice melt(aerial images show ice melting; temp rising)
  • sea level rise(10-20cm in 100 years)
  • tree rings(wider in warm temp, thinner in cold)
• natural causes for climate change:

  • orbital changes(when earth is closer to sun its warmer; circular to elliptical)
  • sunspots
  • volcanic activity(gases released trap heat in atmosphere; sulfur dioxide has a cooling effect though- reflects sunlight back to space)
• human causes for climate change:

  • fossil fuels(enhanced greenhouse gas effect)
  • farming(methane produced)
  • deforestation(trees release CO2 when burnt)