1A - The Challenge of Natural Hazards

natural hazard

natural hazard

• extreme natural events that can cause loss of life, extreme damage to property and disrupt human activities

• a natural disaster is a natural hazard that has already happened

geological hazard

• caused by land and tectonic processes

• include volcanoes, earthquakes, landslides and avalanches

meteorological hazard

• caused by weather or climate

factors affecting hazard risk

hazard risk - the probability of people being affected by a hazard in an area

vulnerability

• population - the more people that are in an area exposed to natural hazards, the greater the probabaility they will be affected by a natural hazard.

capacity to cope

• the better a population can cope with an extreme event, the lower the risk of them being severely affected

• HICs can do this better than LICs

phyiscal geography of an area

• flat, mountainous, island, landlocked etc

nature of natural hazards

• type - the risk from some hazards is greater than others e.g tropical storms can be predicted and monitored, giving people time to evacuate but earthquakes can happen very suddenly with no warning so it is harder to protect people

• frequency - natural hazards that occur more frequently carry a higher risk

• magnitude - move severe natural hazards tend to have the greatest effects

primary and secondary effects of natural hazards

primary (immediate) effects

• building and road destruction

• deaths and injuries

• crops and water supplies damaged/contaminated

• electricity cables, gas pipes and communication cables damaged

secondary

• initial hazard can trigger other hazards

• emergency aid unable to get through due to blocked roads

• lack of clean water and sanitation could lead to diseases spreading

• country’s economy weakened

immediate and long term responses to natural hazards

immediate

• evacuate people

• treat the injured and rescue people

• temporary food and water supplies

• foreign governments providing aid workers and money

long term

• repair houses

• repair buildings and roads

• improve forecasting/mmonitoring and evacuation plans

• promote tourism to boost economy

continental vs oceanic crust

continental

• thicker

• 30-50km

• less dense

oceanic

• thinner

• 5-10km

• more dense

tectonic plates

• the crust is dived into these and they float on the mantle

• the plates move due to convection currents in the mantle

• places where the plates meet are plate margins or plate boundaries

destructive margins

• two plates moving towards each other

• oceanic plate meets a continental plate and the denser oceanic plate is subducted under the continental plate

• pressure due to friction melting rock increases

• due to heat and pressure it melts into a pool of magma

• this magma then rises through vents

• this then forms destructive volcanoes which are very powerful

constructive margins

• plates move apart, causing magma to rise up between to fill the gap

• resulting volcano is not very powerful

• this creates shield volcanoes

conservative margins

• plates side paralell past the other along a fault

• can be the same direction but at different speeds

• strike and slip

• pressure causes earthquakes

collision margins

• similar plates collide

• no subduction

• land is forced up to bend and reform into fold mountains

how earthquakes happen

• tectonic plates are all constantly moving

• sometimes they get stuck, so when they finally move, they release a lot of energy in the form of seismic waves

• since it can release the tension at any point, earthquakes are unpredictable

parts of an earthquake

• focus - the point in the earth where the earthquake starts

• epicentre - the point directly above the focus, on the earth’s surface

• seismic waves are vibrations from the earthquake which are strongest near the epicentre

Haiti 2010 eathquake - background

• epicentre - 16 miles from Port Au Prince (capital with pop 2.5M)

• lasted 35s

• magnitude 7.0

• carribean

• poorest country in the NW hemisphere - GDP per capita $849 per annum in 2014

• North American and carribean plates - conservative boundary

Haiti earthquake - causes

• Port Au Prince was built on soft sediment

• 2-4 storey buildings and lack of steel reinforcements lead to pancake collapse

• shallow earthquake

Haiti earthquake - primary effects

• 300,000 injured

• 220,000 dead

• buildings completely collapsed

• loss of power lines and communications

• few hospitals left in tact

• harbour collapsed

• 1.5M left homeless

Haiti earthquake - secondary effects

• cholera outbreak caused by poor sanitation

• 1 in 5 lost jobs

• looting due to lack of food and clean water

• prisoners forming gangs after being released when prisons collapsed

• cost of damages $7.9B

• people died awaiting aid and poor living standard not improved

Haiti earthquake - primary responses

• rubble remained mostly unmoved - 10 months on, only 2% was moved

• 1500 camps set up in port au prince and 81000 people placed in them - hugely inadequete for health and safety

• food and water aid had been donated by many countries but was unable to reach people due to the collapsed harbour

• 1 delivery of drinking water after a week

• bodies collected and buried in mass graves - even this was not implemented properly - slum areas were not well informed so many trued keeping infected bodies in crowded living spaces, allowing cholera to spread

• rules not properly enforced

Haiti earthquake - secondary responses

• world bank cancelled half of Hait'i’s debt

• NGOs set up temporary schools + raised mony

• gov refused to make a decision due to upcoming election

• food rations reached 4.3M people eventually

• water and hygeine reached 1.7M

• building codes introduced for new builds to make them safer - mostly ignored

Japan 2011 earthquake - background

• epicentre 400km from Tokyo

• lasted 6 mins

• magnitude 9.0

• located on the Eastern edge of the Earasian plate which is subducted by the pacific plate (destructive)

Japan 2011 earthquake - causes

• a slippery clay layer was found lining the fault which allowed the plates to slide50m

• shallow

Japan 2011 earthquake - primary effects

• around 16,000 died

• 26,000 injured

• 131,000 displaced and 2600 missing

• 332,400 buildings, 2126 roads, 56 bridges and 26 railways were damaged or destroyed

• land and plate shifts and landfall in beach fronts

• 7 reactors at fukushima had a meltdown - 8x more radiation

Japan 2011 earthquake - secondary effects

• transport disrupted on a large scale

• 4.4m w/o electricity in NE

• tsunami caused pollution further in land

• rural areas for much longer

• cost of damage $235B

Japan 2011 earthquake - primary responses

• Japan Meteorological Agency issued tsunami warnings 3 mins before

• modelling + forecasting technology used to direct responses to appropriate regions

• 100,000 members of Japan’s self defense force mobilised along w/ rescue workers to aid search and rescue within hours

• 11 military aircraft in action to identify priority areas within 30 min

• all rubble cleared within 2 days, allowing emergency goods to be dellivered twice daily

• gov declare 200km evac zone around fukushima

• help from US, NZ, India SK and Australia

• temporary shelters

Japan 2011 earthquake - secondary responses

• evacuees from Fukushima had their health monitored

• 1 month later, reconstruction policy set up to build tsunami resistant communities

• japan move forward committee wanted youth to be involved in the planning and rebuilding

• by nov 2011, 96% of the electricity supply, 98% of the water supply and 99% of the landline network were restored

• gov approved of a scheme to attract investment in the tohaku region

• seawalll

• repairs to tohaku railway and sendai airport

reasons for living in high risk areas

• cannot afford to move

• persecution/conflict

• don’t know the risks

• have always lived there - moving meand leaving jobs and families

• in wealthier countries, effective monitoring and evacuation plans can minimise risk

• confident that their government will support them after an earthquake or volcanic eruption

• minerals from volcanic ash makes volcanic soil very fertile - good for farmers

• volcanoes are tourist attractions - live nearby to work in the tourist industry

management to reduce the effects of tectonic hazards

monitoring

• for earthquakes, seismometers and lasers monitor earth movements and can be used in early warning systems

• before an eruption, small earthquakes, escaping gas and changes in volcano shape can be detected

prediction

• earthquakes cannot be reliably predicted but where they may occur can be forecasted by monitoring the movement of tectonic plates

• volcanic eruptions can be predicted if the volcanoes are monitored closely over a long time

protection

• new buildings can use reinforced concrete that will absorb an earthquake’s energy. existing buildings and bridges can be strengthened with steel frames so they’re less likely to collapse. automatic shut off switches can turn off gass and electricity supplies to prevent fires

• buildings can be strengthened so that they’re less likely to collapse under the weight of ash

planning

• future developments can avoid high risk areas

• emergency services can prepare - practice rescuing

• people can be educated o they know what to do in the event of a hazard

• governments can plan evac routes to gey people away quickly and safely

• emergency supplies can stockpiled

Global atmospheric circulation

• GAC is the transfer of heat from the equator to the poles by the movement of air

• air moves due to differences in air pressure - winds blow from high pressure areas to low pressure areas

• each cell has warm rising air that creates a low pressure belt and cool sinking air that creates a high pressure belt

• each hemisphere has three cells

• hiigh pressure - cool air descends

• low pressure - warm air ascends

How air moves

• the sun warms the earth at the equator, causing the air to rise, creating a low pressure belt and rainfall.

• as the air rises and reaches the edge of the atmosphere, it cools and moves away from the equator to the north and south.

• at 30 degrees north and south of the equator, cool air sinks, creating a high pressure belt and dry dry conditions

• large air cells are created in this way

• at the ground surface, some of the cool air goes back to the equator as trade winds and the rest goes towards the poles as westerlies. these winds curve due to the earth’s rotation - coriolis effect

• at 60 degrees north and south of the equator, the warmer surface winds meet colder air from the poles. The warmer air rises, creating low pressure

• some of the air moves back towards the equator and the rest moves towards the poles

• at the poles, the cool air sinks, creating high pressure. the high pressure air then moves back towards the equator.

the hadley cell

at the equator, the ground is intensely heated by the sun. this causes air to rise which creates a low pressure zone on the earth’s surface. as the air rises, it ccools and forms thick storm clouds. the air continues to rise up to the upper atmosphere and then the following happens:

• the air separates and starts to move both north and south towards the poles

• when it reaches about 30 degrees north and south, nthe air cools and sinks towards the ground forming the subtropical high pressure zone.

• as the air sinks, it becomes warmer and drier. This creates an area of little cloud and low rainfall where deserts are found

• the hadley cell is then complete. the air completes the cycle and flows back towards the equator as the trade winds

• in the northern hemisphere, the winds flow to the right and are called northeast trade winds. In the southern hemisphere the winds flow to the left and are called the south east trade winds - coriolis force and friction

the ferrel cell

occurs at higher latitudes (between 30 and 60 north and south)

• air on the surface is pulled towards the poles, forming the warm south westerly winds in the northern hemisphere and the north westerly winds in the northern hemisphere

• these winds pick up moisture as they travel over the oceans. at around 60 degrees north and 60 degrees south, they meet cold air which has drifted from the poles

• the warmer air from the tropics is lighter than the dense and cold polar air so it rises up as the two air masses meet

• this uplift of air causes low pressure at the surface and the unstable weathr conditions - much of the wet and windy uk weather is determined by this.

the polar cell

• at the poles, air is cooled and sinks towards the ground, forming high pressure. this is known as the polar high. it then flows towards the lower latitudes

• at about 60 degrees north and south, the cold ar mixes with warmer tropical air and rises upwards, creating a zone of low pressure called the sub polar low

• the boundary between the warm and cold air is called the polar front. it accounts for a lot of the unstable weather experienced in these latitudes.

formation of tropical storms

• develop between 5-30 north and south of the equator when the sea temp is 27 celsius of higher and the wind shear (difference in wind speed) between the higher and lower parts of the atmosphere is low

• Air is heated above the surface of warm tropical oceans (27°C)

• warm air rises rapidly under low pressure

• strong winds form as rising air draws up more air and moisture

• Rising air spins around a calm central eye 50m across - coriolis effect

• Rising air condenses, forming cumulonimbus clouds

• Torrential rainfall travels with prevailing wind

• Loses its source of heat and moisture upon meating land

features and structures of a tropical storm

• circular, hundreds of kilometres wide and usually last 7-14 days

• spin anticlockwise in northern hemisphere and clockwise in southern hemisphere

• centre of the storm is called the eye - up to 50km across - caused by descending air. very low pressure, light winds, no clouds and a high temperature in the eye

• the eye is surrounded by the eyewall, where there’s spiralling, rising air, very strong winds, storm clouds, torretial rain and a low temperature

• towards the edges of the storm the wind speed falls, the clouds become smaller and more scattered, the rain less intense and the temperature increases

Typhoon Haiyan - background

• category 5 tyhoon originated in the pacific ocean

• stuck close to Tacloban, Philippines (SE Asia)

• LIC

• a month prior, it had experienced a deadly earthquake and the year prior, a typhoon so it was low on resources

Typhoon Haiyan - background

• extreme low pressure was caused by warm conditions, deep water and low wind shear which allowed vertical development of the typhoon

Typhoon Haiyan - primary effects

• 28,600 injured and 6201 dead

• 600,000 dispaced and 1785 missing

• 30,000 fishing boats destroyed

• electricity and communications taken out, lasting 1 month

• 40,000 homes damaged or destroyed

• flooding caused landslides + blocked roads

• 90% of tacloban destroyed

• airports destroyed

• crops such as rice and coconuts destroyed

Typhoon Haiyan - secondary effects

• 14M affected

• diseases spread from lack of sanitation

• 6M lost source of income

• dirupted aid arrival due to blocked ports and airports

• looting was rife

• $13B in economic losses

Typhoon Haiyan - primary responses

• 1200 evacuation centres put up

• red cross delivered food aid and UK sent shelter kits

• emergency teams distributed aid on food

• US donated financial and medical supplies

• looting for food due to shortage

• US search and rescue

Typhoon Haiyan - secondary responses

• a cash for work programme paid people to clear debris and rebuild tacloban

• displaced fishermen salvaged items to remake boats

• oxfam supported the replacement of fishing boats

• typhoon shelters made for future evacuation

• relocation to newly built homes away from high flood risk areas

• US donated financial and medical supplies

• 800000 evacuated

climate change affecting tropical storms

frequency

• oceans will vstay at 27 celsius or higher for longer each year so there is a longer period when tropical astorms can form, meaning there may be more storms each year

intensity

• higher sea surface temperatures are likely to result in more evaporation and increased cloud formation, so more energy is released, meaning storms become more powerful

distribution

• as the average ocean temperature rises, more of the world’s oceans could be above 27 celsuis and this may mean that tropical storms can form in areas that haven’y experienced them before

reducing the effects of tropical storms

prediction and monitoring

• storms can be monitored using radar, satellites and aircraft. computer models can then be used to calculate its path

• predicting when and where gives time to evacuate and protect homes and businesses

planning

• future developments, e.g new houses, can avoid high risk areas to limit the number of people and buildings at immediate risk from storm surges and flooding(

• governments can plan evac routes so people know a safe place to go in

  the event of a hurricane and get away quickly to minimise loss of life and injury

• emergency services can prepare for disasters by practising rescuing people from flooded areas

• Preparing disaster supply kits means people have what they need in the

  event of a tropical storm

protection

• buildings can be built to withstand tropical storms. they can also be put on stilts so they’re safe from flood water

• flood defences can be build along rivers and coasts

UK weather hazards

strong winds

• can damage properties and public transport

• uprooted trees and debris can injure + kill

heavy rainfall

• can cause flooding which can damage homes, disrupt transport networks and drown people

• recovering from flooding can cost millions

snow and ice

• injuries from sliping and hypothermia can kill

• schools and businesses could be forced shut and disruption to travel can have economic impacts

drought

• water supplies run low, causing economic impacts from crop failures

• rules to conserve water must be introduced

thunderstorms

• heavy rain, strong winds and lightning can all occur

• lightning can cause fires which can damage property and the environment and occasionally kill

heat waves

• during long periods of hot weather, pollution builds up in the air - heights heat exhaustion and breathing difficulties - death

• disruption to transport from rains buckling or roads melting can have economic impacts

• tourism industry may benefit

somerset levels flooding - background

• from dec 2013- feb 2014, somerset experienced 3 times the average amount of rainfall for those months

• lots of rain fell on already saturated ground and coincided with high tides and storm surges, causing extensive flooding of an area of low lying land crossed by rivers

• the rivers hadn’t been dredged (cleared of sediment) regularly for 20 years which reduced their capacity

somerset levels flooding - social impacts

• more than 600 homes were flooded and many people were forced to evacuate

• villages such as Muchelney were cut off by road, and the only way in or out was by boat

• major transport links including the A361 and some train lines were closed or disrupted

• insurance prices soared and some residents were unable to insure their homes against future flooding

somerset levels flooding - environmental impacts

• 11500 hectares were flooded, including farmland, destroying many crops

• standing water made the ground toxic and unproductive for over a year. Loss of nutrients and damage to soil structure decreased the long term fertility of land

• tonnes of mud and debris were left by the floods, damaging vegetation further

somerset levels flooding - economic impacts

• the total cost of damage to the somerset levels - estimated over £80 million

• local companies lost more than £1.2 million in nbusiness

• loss of tourism cost the county £200 million

somerset levels flooding - management strategies

• before the flood

  • warning systems gave people time to prepare -met office said to find emergency accomodation

  • sand bags and floorboards to limit flood damage to buildings

• since the flood, the government has has set up the |”somerset levels and moors flood action plan” - 20 year plann which paims to limit the risk of future flooding. £100 million will be spent on

  • turning temporary pumping stations into permanent ones

  • regular dredging of the rivers parrett and tone

  • building a tidal barrage at bridgewater

  • widening the river sowy’s channel and king’s sedgemoor basin

evidence of climate change

• climate change is any significant change in the earth’s climate over a long period

• the quaternary period is the most recent geological time period, spanning from about 2.6 million years ago to present day

• in the period before the quarternary, the earth’s climate was warmer and quite stable but then it changed

• during the quarternary, global temperature has shifted between cold glavial periods that last for around 100,000 years and warmer interglacial periods that last for around 10,000 years

• the last glacial period ended around 15,000 years ago. since then, the climate has been warming

• global warming describes the sgar rise in global temperatures over the last century

more evidence for climate change

ice and sediment cores

• ice sheets are made up of layers of ice - one layer formed every year

• these can be drilled into to get long cores of ice

• by analysing the gases trapped in the layers of ice, the temperature of each year can be estimated as well as the composition of the atmosphere

• the remains of organisms found in cores taken from ocean sediments can also be analysed

pollen analysis

• pollen from plants gets preserved in sediment

• it can be dated to show which species were living at the time

• preserved pollen from similar plants to today can indicate similar climate conditions

tree rings

• as a tree grows, it forms a new ring each year - tree rings thicker in warm, wet conditions

• these can be counted to find the age of a tree. the thickness of each ring shows what the climate was like

• reliable for climate change for the past 10,000 years

temperature records

• since the 1850s, global temperatures have beeen measured accurately using thermometers

• this gives reliable short term record of temperature change

• historical records like harvest dates or newspaper weather reports can extend the record of climate change further back.

natural causes of climate change

orbital changes (milankovich cycles)

• affect how much solar radiation the earth recieives - more energy means more warming. Changes in the following change the lengths of the glacial and interglacial periods.

• variations in the way the earth orbits the sun

  • stretch/eccentricity - varies from circular to elliptical every 100,000 years

  • tilt - earth’s axis tilded at an angle as it orbits the sun 41,000 years

  • wobble/precession- the earth’s axis wobbles every 26,000 years

volcanic activity

• major volcanic eruptions eject large quantities of material into the atmosphere

• some of these ash particles block out reflect the sun’s rays back out to space so the earth’s surface cools

• sulfur released leads to sulfuric acid droplets that reflect more of the sun’s radiation away

• volcanic activity may cause short term changes in the climate

sun spots

• sun spots and and hotter darker patches on the sun that appaer on an 11 year cycle

• reduced solar output may coo some areas of earth but it doesn’t have a major effect

human causes of climate change

burning fossil fuels

• co2 is released into the atmosphere when fossil fuels like coal, oil, natural gas and petrol are burnt

farming

• livestock produces a lot of methane

• rice paddies - flooded fields emit methane

cement production

• made from limestone which contains carbon. lots of co2 released into the atmosphere

deforestation

• plants remove co2 from the atmosphere and convert it into organic matter using photosynthesis

• when trees are cut down, they stop taking in co2

• co2 is released when trees are burnt down

enhanced greenhouse effect

• IR short waves from the sun hit earth

• Earth absorbs some of the heat

• some of the heat escapes back into space

• atmosphere absorbs some of the heat and traps it, allowing it to hit earth again

• more heat is trapped as greenhouse gas layers increase.

effects of climate change on the environment

• warmer temperatures are causing glaciers to shrink and ice sheets to melt. melting land ice meants that water stored on land is returning to the oceans, causing sea levels to rise

• sea ice is also shrinking, leading to thes loss of ploar habitats

• rising sea levels mean low lying and costal areas will flood more regularly. costal erosion will increase and some coastal areas will be submerged - habitat loss

• other species such as coral reefs are suffering from bleaching (rising sea temperatures make corals expel the algae that live in them, starving them)

• precipitation pattern are changing - affects how much rain areas get

• distribution and quantity of some species could change and biodiversity decrease

  • some species now live at higher altitudes to do warming temps

  • some habitats are being damaged or destroyed - species that are afapted to these envirnoments may become extinct

effects of climate change on people

• in some places, deaths due to heat have increased but deaths due to cold have decreased

• some areas could become so hot and dry that they’re difficult or impossible to inhabit and lead to migration and overcrowding in other areas

• some areas are struggling to supply enough water for residents due to problems with water availability caused by changing rainfall patterns - could lead to political tensions especially where rivers cross borders

• globally, some crops have suffered from reduced yield due to warming

• but some farmers in high latitude countries are finding that their crops benefit from the warmer conditions

• lower crop yieldscould increase malnutrition, ill healrh and starvation

• more extreme weather - money spent on predicting, reducing impacts and rebuilding

mitigation strategies aiming to reduce the causes of climste change

planting trees

• increases the amount of co2 that is absorbed from the atmosphere through photosynthesis

carbon capture

• designed to reduce emissions from power stations burning fossil fuels

• CSS involves capturing cO2 and transporting it to a safe place where it can be stored as a solid or liquid deep underground

alternative energy production

• replacing fossil fuels with nuclear or renewabke energy can help reduce greenhouse gas emissions

• in the uk, more offshore wind farms are being build

adaptating to the effects of climate change

changing agricultural systems

• changing rainfall patterns and higher temperatures will affect the productivity of existing systems

• may be necessary to plant new crop types that are more suited to the new climate conditions in the area

• in some regions, biotechnology is being used to create new crop varieties which are more resistant to extreme weather events

managing water supply

• dry areas are predicted to get even drier - more water shortages - people need to use water more efficiently

• water meters can be installed in homes to discourage excessive water use

• rainwater and waste water can be collected and recycled

coping with rising sea levels

• at current rates, sea levels are predicted to rise about 65cm by 2100 - would flood many islands and costal areas

• better flood warning systems are being put in place and physical defences such as flood barriers are being built

• in areas that can’t afford expensive flood defences, people are building on raised flood shelters and houses on embankments