natural hazards Flashcards
what is a natural hazard
a natural event which poses potential risk of damage to property or loss of life
different types of natural hazard
- tectonic hazard
- atmospheric hazard
- geomorphological hazards
- biological hazards
factors effecting hazard risk
- magnitude
- population density/ urbanisation
- deforestation
- global warming
different types of crust
- continental (thicker and less dense)
- oceanic (thinner and denser)
how do tectonic plates move?
- ridge push and slab pull
what happens at constructive plate margins
- upper part of mantle melts and hot magma rises
- plates move away from each other due to slab pull/ ridge push, and magma rises in between, before cooling down as solid rock to form part of oceanic plate
- forms shield volcanos
what happens at destructive plate margin (continental)
- both continental plates are buoyant and cannot sink into mantle, meaning compression forces the plates to collide and form mountains
what happens at destructive plate margin (continental and oceanic)
- the denser oceanic plate is subdued and sinks under continental plate and into mantle
- earthquakes, fold mountains and volcanoes occur
what happens at conservative plate margins
- two plates move parallel to each other, either in the same direction or opposite direction
- pressure is built up due to friction of both plates when they become stuck, causing earthquakes when the rock eventually fractures
case study for LIC/NEE earthquake
- Gorkha, Nepal (2015)
- LIC
case study for HIC earthquake
- L’aquila, Italy (2009)
Gorkha earthquake stats
-7.8 on richter scale
- 8,841 dead
- 16,800 injured
- 1 million made homeless
- 26 hospitals destroyed
- 50% of schools destroyed
L’aquila earthquake stats
- 6.3 on richter scale
- 308 killed
- 1,500 injured
- 67,500 made homeless
- house prices and rent increased due to lack of housing (long term)
immediate responses to l’aquila earthquake
- hotels provided shelter for 10,000 people
- 40,000 tents given out
- Eu granted $550 million to help rebuild L’aquila
long term responses to L’aquila earthquake
- homes took several years to rebuild and historic centres expected to take approx 15 years to rebuild
immediate responses to gorkha earthquake, nepal
- Uk’s DEC raised $126million to provide emergency aid and start rebuild
- temporary shelters set up- tents for 225,000 people provided by red cross
- WHO distributed medical aid
long term responses to gorkha earthquake
- Nepal’s government carried out Post- disaster needs assessment, which reported 23 areas need rebuilding
why do effects and responses of earthquakes differ?
- depends on level of development -ie HIC, LIC, NEE etc, which effects the ability to predict, protect and prepare for hazard
different factors affecting effects of earthquakes
- magnitude
- depth of focus (shallower = more effect)
- pop density
- building density
- distance from epicentre
pull factors for living in high volcanic and earthquake risk areas
- geothermal energy- steam heated by hot magma
- farming- nutrient rich, fertile soil
- mining- makes more than on a coffee plantation
- tourism
- family/ friends
how can risks of natural hazards be reduced
- monitoring
- protection
- prediction
- planning
how can monitoring and prediction reduce risk of earthquakes
- Seismologists use radon detection to find radon in soil and groundwater, as it escapes form cracks in earth’s surface
- seismometers used to measure tempers or foreshocks
- locations and times of earthquakes mapped to spot patterns- predict next one
- animals believed to act strangely before earthquakes
how can protection reduce risk of earthquakes
- designing buildings, roads and bridges built to withstand earthquakes provides protection- mitigation
- however this is expensive and cannot always be achieved
how does planning reduce risk of earthquakes
- furniture and objects fastened down
- residents taught how to turn off gas, electricity and water supplies
-preparing emergency aid supplies and how to distribute- saves lives as response faster - earthquake drills
how does monitoring and prediction reduce risks of volcanic eruptions
- satellites and telemetry’s monitor ground deformation
- seismometers measure small earthquakes and tremors
- thermal heat sensors detect changes in temp of volcano’s surface
how does protection prevent risk of volcanic eruptions
*extremely difficult- doesn’t really happen
how does planning prevent risk of volcanic eruptions
- evacuation plans
- preparation of emergency shelter and food supplies
- exclusion zones (nobody can enter)
- if unable to evacuate, residents told to seek shelter or go indoors to prevent dangers of ash and rock
how do tropical storms form
- warm air rises to create an area of intense low pressure
- as warm, moist air reaches high altitudes, powerful winds spiral around calm central point due to coriolis effect creating the ‘eye’
- warm air cools and condenses into heavy rainfall and thunderstorms
where are hurricanes found
- Atlantic and Eastern Pacific Oceans
where are typhoons found
- North pacific ocean
conditions needed for tropical storms
- between 5-30 degrees N and S of equator
- sea temp above 27 degrees C
- sea depth of approx 60-70 metres
- Low wind shear
where are cyclones found
- indian and south pacific ocean
Where are Hurricanes found
- Atlantic Ocean
Where are Typhoons found
- Pacific Ocean
Which direction do Tropical storms spin in Northern Hemisphere
- Anti-clockwise
Which direction do tropical storms spin in Southern Hemisphere
- Clockwise
How to categorise tropical storms
- CAT 1-5 on Saffir-Simpson scale
What is it called when storm reaches land
- Making Landfall
What happens when storm reaches landfall
- Dissipates due to there no longer being enough evaporation to fuel the storm
Process of formation of tropical storm:
- Sun’s radiation warms oceans to 27 degrees
- Warm moist air rises creating low pressure at centre of storm
- as air rises it cools, causing condensation to occur, leading to rain
- Air rushes in from higher pressure areas outside storm to lower pressure at centre creating strong winds
- Whole storm rotates due to Earth’s spin
How could climate change effect distribution of tropical storms
- Increased global water temperatures mean more areas are warm enough to have tropical storms
How could climate change effect intensity of tropical storms
- Warmer water means hurricane is stronger
How could climate change effect Frequency of tropical storms
- Higher water temps increase possibility of tropical storms
Primary effects of Tropical storms
- People injured/killed by debris
- Buildings destroyed by debris or storm surge
- People drown in storm surge
- Water supplies contamination
- Road and rail networks blocked by debris
Secondary effects of Tropical storms
- Crops/livestock killed can lead to food shortage
- people left homeless
- Electric supplies cut off due to power line damage
- Sewage released due to flooding
- Water borne diseases due to poor sanitation
- Unemployment due to businesses being damaged
Immediate responses of tropical storms
- People evacuated before landfall
- Trapped people rescued
- medical support provided for injured
- Temporary shelters for evacuees
- Food and water supplied to people
- Dead bodies recovered
Long term responses of tropical storms
- repair and rebuild properties
- rehouse people
- repair transport infrastructure
- provide grants and aid to people to help rebuild their homes
- BBB- Build back better
Name of Tropical storm case study
- Typhoon Haiyan
How many killed in Haiyan
- 6,340 people
How many made homeless in Haiyan
- 670,000
How many islands in Philippines
- 7000
Category of Haiyan
- Cat 5 on Saffir Simpson scale
Fastest wind in Haiyan
- 315Kph- fastest ever recorded tropical cyclone
When Haiyan made landfall?
- Nov 7 2013
How much of city of Tacloban destroyed by Haiyan
- 90%
How many farmers and fishers lost source of income in Haiyan
- 3/4
How big was Haiyan’s storm surge in Tacloban
- 5 metres
Secondary effects of Haiyan
- 6 million lost source of income
- 8 deaths in stampede for rice supplies
- Rice prices risen by 12% in 2014
How many fishing boats destroyed in Haiyan
- 30,000
Immediate responses to Haiyan
- 1200 evacuation centres set up
- International governments and aid agencies supplied food, water and emergency shelters
- RAF and Royal Navy provided thousands of litres of water and 100,000 tonnes of rice
Long term responses to Haiyan
- UN countries donated financial aid, supplies and medic support
- Rebuilding of roads, bridges and airports
- ‘Build back better’
What is Build back better
- A scheme by ‘plan international’ which gave visual guides to local people on how to build more resilient houses
Why was it hard for effective immediate response for Haiyan
- Hundreds of effected islands made it hard to co-ordinate- no land vehicles could be used
What is tropical storm planning
- Telling people way they need to do in a tropical storm
How does tropical storm planning help
- People more prepared, therefore act more decisively and less loss of life
Examples of tropical storm planning
- Fuel up vehicles in advance
- Store loose objects to prevent debris
- prepare supply kits
- Learn locations of evac centres
What is tropical storm prediction
- Putting weather data into supercomputers which can run models to predict path/intensity of storm
How does prediction reduce impact of T.S
- Use prediction to see where storm his heading to issue warnings in these areas
Example of Prediction
- Cyclone in india in 2013 was successfully predicted leading to 1.2 million evacuees
What is tropical storm monitoring
- Tracking/observing storms to see where they are/their magnitude
How monitoring reduce impact of T.S
- Allow predictions to be made which saves lives and reduce damage
Example of T.S monitoring
- Global precipitation measurement satellite monitors precipitation every 3hrs between 65 degrees N and S of equator
What is T.S protection
- Making buildings stronger and more resistant to storms
How does protection reduce impact of T.S
- Stronger buildings means less damage to properties
- Also means less debris flying around which reduces danger
Examples of T.S protection
- Storm shutters in windows
- Tying down objects that could get blown
- Reinforce doors
What is weather
- State of atmosphere at a particular place and time
What is climate
- Weather conditions prevailing in an area over a long period (30yrs)
What is extreme weather
- A weather event which is especially severe and significantly different from the average, typically unseasonal and different from usual weather pattern
Case study for extreme weather event in UK
- Beast from the east, 2019
Impact of Extreme cold weather
- Travel disruptions and safety concerns lead to school and business closure
- death of livestock
- slipper conditions- risk to health
- money spent on salting and gritting
Impact of gales (strong winds)
- Buildings, transport links and electricity lines damaged
- Debris could block roads
Impact of thunderstorms
- Lighting can cause fires, electrical surges, deaths and building damage
- flash floods could occur
Impact of heatwaves
- Deaths due to health issues- heat exhaustion and breathing difficulties
- crops scorches and livestock killed
Impact of droughts
- Crop failure
- Water conservation methods such as hose pipe bans
Impact of heavy rain
- (Flash)floods damage buildings, transport links and energy supplies
- livestock and crops killed
- expensive reparations
Causes of Beast from the east
- Change in Northern polar jet stream, which drew cold air to UK
- Air picked up moisture over North Sea bringing snow
- Huge amount of snow dumped on UK
Primary effects of Beast from East
- 4 reported deaths
- upto 50cm of snow in some places
- 60-70mph winds in Northern England and Wales
Secondary effects of beast from east
- Hundreds of flights cancelled from Heathrow
- Thousands of schools closed
- Over 8000 collisions in 3 days due to conditions, costing over £10m in insurance
- Scottish premiership postponed games
Responses to beast from east
- Army called in to help people
- Met office issued red warnings
- Councils sent out gritters and ploughs to clear roads
- Public Heath England urged people to ensure they had enough food and meds
Evidence for UK weather becoming more extreme
- 2022 had record breaking temps
- 2020 Feb had 4x average rainfall
- increase in frequency for heatwaves- used to be every 3 yrs, now every 200 days
Evidence for Uk weather not becoming more extreme
- UK hasn’t seen overall change in annual rainfall
- We don’t have enough evidence over a long enough period
What is climate change
- Very long term shifts in weather patterns
Evidence of Climate change in past
- Glaciated landscapes
- Fossils of animals in unusual places, showing different climates in past
Evidence of climate change today
- Sea levels rising
- Increase in temp
- Ice caps melting
- increased extreme weather
How much sea level risen in last 100 years
- 10cm
Natural causes of climate change
- orbital changes
- Solar output
- volcanic activity
How does solar output cause climate change
- ‘Sunspots’ randomly form on surface of sun, leading to more solar output and so high temperature
How do orbital changes lead to climate change
- Earth’s orbit changes from circular to elliptical shape every 100,000 years, causing colder (glacial) periods
How does volcanic activity lead to climate change
- In short term, volcanic ash blocks out sun, reducing temp on earth
- In long term, sulphur dioxide turns into sulphuric acid, which reflects radiation form sun
Sources of greenhouse gases
- Industry- releases CO2
- Deforestation- releases CO2 as carbon sinks burned
- Agriculture- livestock produce methane
How does enhanced greenhouse effect work
- Increased greenhouse gases released leads to thicker layer of greenhouse gases, which traps heat inside Earth’s atmosphere increasing temp
Effects of climate change on people
- Diseases more rife in hotter climates
- Melting snow in ski resorts can ruin economy in these areas
Effects of climate change on Environment
- More extreme weather could lead to forest fires in hot areas
Effect of climate change on Environment AND people
- More frequent droughts and flooding lead to crop failure and so starvation
- Melting ice caps leads to rising sea level meaning some have to leave their homes in coastal areas
What is mitigation
- strategies to reduce causes of climate change and therefore reduce impacts
What is adaptation
- Strategies to responses to new conditions of climate change to make populations less vulnerable to negative impacts
Example of mitigation
- Taxing cars that produce more CO2- ULEZ
Example of adaptation
- Farmers changing crops which are more suited to new conditions
