Geography GCSE- The Challenge of Natural Hazards

Natural Hazard- a naturally occuring event that has a huge social impact 

• atmospheric= wind/ drought/ hurricane/lightning
• flooding= tsunami/flood/mudflow
• geological=tsunami/avalanche/landslide/volcano/earthquake

Hazard Risk= the chance/ probability of being affected by a natural hazard

Factors Affecting Risk=

• Urbanisation- hazards will have greater impact on densely populated/ developed areas
• Climate Change- causes extreme events/ places wetter or drier= increased risk
• Poverty- forcing people to live in risk areas/ lack of resources to prevent/ protect hazards
• Farming- farmers live on floodplains as very fertile

Why live in areas at risk?

• lack of knowledge/ living in povert so no choice/ no event before so aren't aware
• events don't happen that often/ faming/ weigh up advantages

Earth's Layers=

• inner core, outer core, mantle- 2900km wide, semi solid with magma, convection currents
• Crust- solid outer layer, 5-60km thick, broken into plates- oceanic and continental

Earthquake- a sudden and violent period of ground shaking

Volcano- an opening in Earth's crust from which lave, ash and gases erupt

Plate Margins=

• Constructive- plates away from each other due to cc in mantle, magma rises= v, movement= e (Mid Atlantic Ridge)
• Destructive- plates move towards each other and collide, denser oceanic subducted under continental, trench in subduction zone where oceanic sinks to form magma= rises into v, friction of subduction causes e, if both continental- fold up for fold mountains (Nazca under South American)
• Conservative- plates move past each othera nd get stuck= friction and pressure= seismic waves relaesed= earthquake (San Andreas Fault)

Factors Increasing Effect-

• Magnitude- higher= more damage, depth of focus- shallower= more destructive
• Level of development- richer= better protection, time of day- night= people sleeping
• Population density- higher= more casualties, distance from epicentre- more severe at centre

Chilian Earthquake 27th Feb 2010-

• Magnitude= 8.8, destructive plate margin, pacific ocean, waves at 800km/h
• Development= life expec 81, GNI 22,540, HDI rank= 41/187

Primary Effects (immediate)-

• 500 killed, 12000 injured, cost $30bil, many lost water/ power, 220000 homes, 4500 schools destroyed

Secondary Efects (hours, days, years after)-

• 1500km roads damaged, coastal towns devastated, fire at chem plant near Santiago

Immediate Responses-

• international help for field hospitals/ emergency services, temporary repairs to highway in 24hrs
• power/water restored 90% homes in 10 days, national appeal $60 mil= 30k emergency shelters

Long Term Repsonses-

• reconstruction plan help 200,000 households affected, strong economy easily rebuilt

Nepal Earthquake 25th April 2015-

• Magnitude= 7.9, destructive, 15km below surface, epicentre 80km from capitol Kathmandu
• Development= life expec 69, GNI= 2520, HDI rank= 145/187

Primary Effects-

• 1/3 pop affected, 9000 died, 20,000 injyred, 3mil homeless, 1.4mil neede food/ water/ shelter, 7000 schools destroyed, $5bil damage

Secondary Effects-

• landslides/ avalanches blocked roads, Mt ev avalanche killed 19, av in langtang 250 missing

Immediate Repsonses-

• helicopters resuced mountain people and devlievred aid to cut off towns, 1/2mil tents, field hospitals supporting overcriwded hospitals, 300,000 migrated from Kathmandu

Long Term Responses-

• lakes emptied/ landslides cleared, 7000 schools rebuilt, Aug 2015 everest routes created= tourism

Living on an Active Plate Margin Advantages=

• cheaper energy, heating for homes, water for energy
• beautiful views, shelter from wind, photo opportunities

Monitoring= using scientific equip to detect warning signs of events

• remote sensing- detect heat and shape changes, seismicity- seismograph records earthquakes
• geophysical measurements- changes in gravity, hydrology- gases dissolved in water

Prediction= historical ev/ monitoring= predictions of when and where event might happen

• can predict volcanoes from scientific monitoring
• can't predict earthquakes as lack of clear warning signs, but know areas at risk

Protection= designing hazards to withstand tectonic hazards

• earth embankments/ explosives to divert volcano lava
• tsunami walls near nuclear power stations/ coast
• shock absorbers/ concrete columns, auto shutters for earthquake protection

Planning= identifyig and avoiding places most at risk

• hazard maps for volcanoes, maps for earthquakes to protect high value land uses (hsopitals)

• Coriolis Effect- winds distorted by earth's rotation
• Greatest Insolation- (input of energy from sun)= equator
• Pressure- around earth, move n and s during year (with the seasons)

Circulation=

• At equator concentrated sun energy, warm air rises, low pressure belt= air rises and cools= clouds and high rainfall in equatorial regions.
• Air separates and moves to higher latitudes, cool air sinks at hot deserts (30 N and S of equator)= high pressure belt= few clouds and little rainfall= hot/dry but cold at night
• Cold polar air mixes with warmer air and rises= high pressure belt, unstable boundary between, rising air cools and condenses into clouds= rainfall (UK 55 N of equator)
• Air cools and sinks= high pressure belt= cold dry climate

Tropical Storms- large areas of low pressure or extreme depressions

• located 5-15 N and S of equator, between tropics
• America= hurricanes, E Asia= typhoons, W Asia/ Africa= cyclones
• need ocean 26.5 degrees and wind- climate change heats oceans= more storms
• In eye= calm weather, in eye wall= stormy/ lightning/ rain/ wind

Typhoon Haiyan=

• 3rd-11th Nov 2013, Philippines (S-E Asia), 170mph winds, 15m high waves
• Caused by tropical moisture clouds in Pacific, category 5 super typhoon

Primary Effects=

• 6300 drowned in storm surge, 600k displaced, 40k homes destroyed,
• 30 k fishing boats destroyed, 400mm of rain= flooding

Secondary Effects-

• 14mil affected, 6mil lost source of income, $4.5bil damage, landslides blocked roads
• Power supplies cut off for a month, airlines disrupted= no interbational help
• Looting/ violence in Tacloban, shortages of food/water= disease outbreak

Immediate Responses-

• international aid= food/water/shelter, 1200 evacuation centres, 
• Philippines Red Cross delivered food aid, US helicopters for search and resue

Secondary Responses-

• homes built away from flood risk, more cyclone shelters, rebuilding
• foreign docs (US, EU, Australia) supported new ops, rice farming/ fishig quickly reestlablished
• Cash for work programmes, aid agencies replaced fishing boats

Monitoring and Prediction-

• early warnings, hurricane modelling, hurrucane track prediction- determine path/ power

Protection-

• houses on stilts= water run through, shutters for wind, bicycles to deliver warnings
• channel below house, natural landscaping absorbs water

Planning-

• Government educate and warn public, weather reports, TV/ radio safety instructions
• water proof bags, disaster kit, pets indoors, cars away from trees, unplug devices

• 2003 Heatwave- 38.5 d in Kent, 2000 died, roads melted, train tracks buckled
• Dec 2010 Heavy Snow- N Ireland -18.7 d at Castlederg

Somerset Levels Floods 2014-

Causes- 31.4cm rain 24hrs, ground already saturated, steep slopes, confluence, swollen rivers

Effects-

• meadows/ farms underwater, can't drive, angry locals

Immediate responses- villagers travel by boat, local communities helped

Long Term Responses-

• £20mil flood action plan, March 2014 8km Rivers Tone/ Parratt dredged, road levels raised
• river banks strengthened, 2024 consideration  to Bridgewater tidal barrage

Causes of Climate Change-

• Orbital Changes- changes circular- ellpitical affecting distance from sun, circular= closer= more heat energy= increased temps, Axial tilt- tilt chages changing temps
• Volcanic Activity- eruptions release SO2 and CO2= ghg that trap sun's radiation= increased temps, ash can block out sun= reduced temps
• Solar Activity- sunspot activity max= sun gives off more heat, explosions on Earth= solar flares= increased temp
• Burning Fossil Fuels- release CO2= ghg= traps sun's heat
• Deforestation- trees absorb CO2 in photosynthesis= reduced absorbtion
• Agriculture farming= methane produced in decomposition/ digestion= ghg

Effects-

• Glaciers and ice sheets melt= loss of polar habitats, species extinct as conditions change 
• Hotter/ drier climate= drought, declining cro yields, desertification= food/ water shortages
• Extreme weather events, change in rainfall, coastal areas flooded as sea levels rise
• Heat related health problems, mass migration and overcrowding to areas away from risk, 

Evidence-

• Sediment Cores- remains of organisms analysed to identify envrionmental conditions/ temps from Quaternary period and compare
• Analysis of Pollen- preserved in lake beds/ bogs and analysed to show plants that grew then compraed to now to show change in climate
• Ice Cores- analyse gas levels in ice to show temp change across time
• Temp Records- global temps with thermomtere since mid 19th century

Management-

• Alternative energy production- using renewabke sources (solar, wind, biofuel)= no CO2 produced (EU target 20% renewable 2020)
• International Agreements- agree to common policies- reduce climate change/ ghg emissions
• Carbon capture- capture CO2 released in industry and storing underground
• Reforestation- more CO2 removed from atmosphere, Conservation International- restore 73mil trees in Amazon by 2023
• Adapting- sea walls for rising sea levels, modify crops (drought resistant), water eficient devices