natural hazards

• what are natural hazards?

  natural hazards are physical events such as earthquakes and volcanoes that have the potential to do damage to humans and property. hazards include tectonic hazards, tropical storms, and forest fires.
• what affects hazard risk?

  • population growth
  • location
  • global climate change
  • wealth
• layers of the earth

  • inner core
  • outer core
  • mantle
  • crust
• the crust is split into major sections called tectonic plates

  there are 2 types of crust:

  oceanic- thin and younger but more dense

  continental- old and thicker but less dense

  these plates move due to convection currents in the mantle, and where they meet, tectonic activity occurs.
• primary effects happen immediately

  secondary effects happen as a result of the primary effects and are therefore often later
• reducing the impact of tectonic hazards

  M-monitoring- seismometers measure earth movements. volcanoes give off gases

  P-prediction- by observing and monitoring data, this can allow evacuation before the event

  P-protection- reinforced buildings and making building foundations that absorb movement. automatic shut offs for gas and electricity.

  P-planning- avoid building in high risk areas. training for emergency services and planned evacuation routes and drills
• Nepal earthquake

  April 2015, magnitude 7.9

  primary effects:

  • 9000 people died
  • 20000 people injured
  • 7000 schools destroyed and hospitals overwhelmed
• Nepal earthquake

  secondary effects:

  • avalanche in Langtang region-250 people missing
  • Avalanches on Mount Everest killed at least 19 people
• Nepal earthquake

  immediate responses:

  • 1/2 million tents needed to provide shelter for the homeless
  • Search and rescue teams, water and medical support arrived quickly from UK
• Nepal earthquake

  long term responses:

  • over 7000 schools needed to be rebuilt or replaced
  • reopen heritage sites by july 2015
• Chile earthquake

  february 2010, magnitude 8.8

  primary effects:

  • 500 people died
  • 4500 schools destroyed
• Chile earthquake

  secondary effects:

  • 1500km of roads damaged by landslides
  • several coastal towns devastated by tsunami waves
• Chile earthquake

  immediate response:

  • power and water restored to 90% of homes within 10 days
  • temporary repairs to route 5 north-south highway within 24 hours
• Chile earthquake

  long term response:

  • housing reconstruction plan- helps 200,000 households affected
  • could take 4 years to fully recover from damage to buildings and ports
• Why do people live near tectonic hazards?

  • people live in poverty- may not have a choice
  • jobs in tourist industry, eg mount etna
  • people have always lived there- don’t want to leave family, jobs
  • fertile soil- from volcanic ash
• Typhoon Haiyan

  november 2013, category 5

  primary effects:

  • about 6300 people killed, most drowned by the storm surge
  • 90% of Tacloban city was destroyed
  • over 400mm of rain caused widespread flooding
• Typhoon Haiyan

  secondary effects:

  • looting and violence broke out in Tacloban
  • 14 million people were affected and many left homeless
  • 6 million lost their source of income
• Typhoon Haiyan

  immediate responses:

  • over 1200 evacuation centres set up to help the homeless
  • french, belgian, and Israeli set up field hospitals to help
• Typhoon haiyan

  long term responses:

  • rebuilding of roads, bridges, and airport facilities
  • new homes built away from areas at risk of flooding
• earthquake key terms

  Focus= centre of the earthquake

  epicentre= directly above the focus

  seismic waves/ waves of energy released
• Earthquake resistant buildings

  • shear walls to reduce rocking movements
  • cross-bracing to reinforce walls using two steel beams
  • shock absorbers to absorb the tremors of earthquakes
• Global atmospheric circulation= the large scale movement of air in the atmosphere, this movement creates cells
• cells

  cells are essentially winds

  there are 3 types of cells: polar, ferrel, hadley
• Weather hazards= extreme weather events when the weather is markedly different to the average weather in the area.
• Effects of extreme weather:

  • Roads and train lines buckling (heat waves)
  • Damaged forests, power lines brought down (hurricane/winter storm)
  • flooding, transport disruption (heavy rain)
  • school closures, deaths, injuries (snow)
  • crop failure, hosepipe ban (drought)
  • fires, benefits to tourism (heat waves)
• Evidence for more extreme weather:

  • warmest temp for jan recorded in scotland (19.6 in jan 2024)
  • 10 warmest years for Uk since 1884 have occurred since 2002
  • 6 of 10 wettest years have happened since 1988
  • far fewer very cold days
• When there are trade winds, it causes low pressure. Westerlies create high pressure
• Why areas near the equator have high rainfall:

  Hot air rises at the equator which cools and condenses to form clouds, which have lots of moisture, causing lots of rainfall.
• Tropical storm= an area of very low pressure surrounded by a rotating mass of fast wind. also known as a hurricane, typhoon, or cyclone.
• How are tropical storms formed?

  • upward movement of air draws water vapour from the warm ocean surface
  • The evaporated air called as it rises, condenses and forms thunder storm clouds
  • As the air condenses it releases heat, this powers the storm and draws up more water from the ocean
  • Several small thunderstorms drawing to make one giant spinning storm. when wins reach 75 mph, the tropical storm is born
• How is a tropical storm formed? Pt. 2

  • An eye develops where the rapidly falls the most intense weather is at that the eye wall
  • As the storm is carried across the ocean, it gets stronger
  • When it reaches land it loses its energy friction slows it down, and it starts to die out
• Where are tropical storms normally found?

  Tropical storms are generally found in between two lines to tropic of cancer and the tropic of Capricorn
• When was our last ice age?

  The quaternary period which ended 11.7 thousand years ago
• What evidence do we have for climate change?

  • ice and sediment cores- repeat photography shows glaciers shrinking, satellite monitoring should ice cap/glaciers shrinking, ice core samples provide data of past climates
  • tree rings which are closer together means there is less growth so a colder climate. tree rings that are spread out mean there was more growth so a warmer climate.
  • plant pollen- scientist can analyse pollen preserved deep in lake floors and match this to plants. Some plants can only grow in certain climate conditions.
• Causes of Climate change:

  • rice production- rice paddies contribute to global warming, as flooded fields emit methane
  • farming- farming livestock produces a lot of methane, through cow‘s burps and farts
  • burning fossil fuels- co2 release when fossil fuels are burnt, eg in power stations or cars
• Causes of climate change Pt.2

  • deforestation- when trees are cut down, they stop taking in co2. Co2 is released into atmosphere when trees are burnt as fuel or to make way for agriculture
  • cement production- cement is made from limestone, which contains carbon. when cement is produced, lots of co2 is released into atmosphere
• Adaptation= when we change our way of life to live with an environmental change.

  mitigation= when we take action to try and prevent or slow down a process from happening.
• Effects of climate change:

  • rising sea levels- cause an increase in floods at coastlines, leading to destruction of houses, so people have to move inland
  • more droughts and wildfires- lead to habitat loss so more species may go extinct (env), wildfires destroy houses so many people left homeless (social), expensive to rehouse everyone into fire-resistant housing (economic)
• What are the positives of global warming?

  • farmers- some farmers in higher latitudes will be able to grow more crops due increases in temperatures
  • tourism- as weather becomes hotter dryer, more tourist will visit countries, eg. the UK economic benefits
• Adaptations to climate change:

  • modified homes- houses built on stilts so that in case of floods, houses are fully protected- so little damage, saving repair costs
  • alternative crops- drought-resistant crops so farmers will still have crops to be sold all year round, even in droughts