The challenge of natural hazards Flashcards
Atmospheric (hydro-meteorological) hazards
hazards that are caused by the weather
- droughts
- floods
- tropical storms
- acid rain
Geological (geophysical) hazards
hazards caused by tectonic plates
- tsunami
- earthquakes
- volcano
- landslides
what’s the relation between natural disasters and natural hazards?
natural disasters are events caused by nature that have actually happened whereas natural hazards are events that have/ can occur that can disrupt humans or damage property
Natural disasters
events caused by nature that can cause disruption to human life and destroy property/ possessions
Why may people choose to live somewhere vulnerable to a natural hazard?
- we can’t accurately predict the hazard (its timing, magnitude and location) so its worth the risk to stay as there is a small chance of being effected.
- we can’t move, some people cannot move due to it being more expensive to do so or they aren’t socially able. Language can be difficult when moving to another country and some are not educated enough to be able to move away.
- don’t want to go, perhaps they strongly believe in their defences or they are optimistic that it won’t happen.
- worth the risk perhaps if the jobs there have high salaries or the land has good natural resources.
What factors affect the hazard risk of natural hazards?
- vulnerability: a densely populated area has a greater risk than a sparsely populated area, timing during the day
- capacity to cope: normally HICs cope better due to their advancements in technology that can predict hazards and issue warnings and they have advanced infrastructure made to cope with the conditions
- nature of the natural hazards: some natural hazards are easier to monitor and predict (tropical storms rather than earthquakes), the magnitude of the hazard and how frequent it is.
how vulnerability affects natural hazard risks:
- natural factors (height of land, geology, and location): soft rock in an earthquake poses more risk as it is more unstable, a funnel shaped coastline can increase the likeliness of a storm surge.
- population density and distribution: greater density = greater risk
how capability to cope affects natural hazard risks:
- management to reduce (prediction, planning and protection): we can monitor some hazards better than others and issue out evacuations, we can build houses to suit the conditions, we can prevent as much damage by carrying out rules
- education on what to do in the circumstances
- how much money can be invested into advanced preparation; HICs
how nature affects natural hazard risks:
- time: when asleep or during working hours = more risk
- frequency: more frequent = less hazard as people become more educated and aware, they aren’t taken by surprise
- magnitude
What 2 factors make tectonic plates movie:
- convectional currents
- ridge push and slab pull
convectional currents
radioactive decay in the mantle produces heat which heats up the magma. as the magma gets hotter it becomes less dense and rises to the surface (crust). as it rises it cools and is forced to disperse in different directions beneath the crust, causing the plates to move in the same convectional current. as the magma cools at the surface, it solidifies and becomes denser, sinking back down to the mantle to melt again and repeat.
ridge push and slab pull
through the cracks in the curst, magma (under lots of pressure from the convectional current in the mantle) escapes from the gap, erupting. this magma now at the surface (lava) cools and creates new plate area, causing the plates to be pushed apart.
slab pull is when at the other end of the plate, the denser plate subjects under the lighter one under gravity. it melts into the mantle feeding the convectional currents which pulls the rest of the plate with it.
Describe how the Mercalli scale measures earthquakes:
the Mercalli scale is a scale of 12, 1 being least destructive and 12 being devastating. this is based on the effects of the earthquake (people’s opinions and observation) and doesn’t measure the energy of the earthquake.
Describe how the Moment scale measures earthquakes:
the Moment scale uses a logarithmic scale from 1 to 10 (1 being the weakest). it uses seismographs to measure the seismic waves given off from the focus. it shows both the intensity of the earthquake but also shows how often the intensity occurs in the world.
Describe the composite volcanoes:
Composite volcanoes occur at destructive plate margins where a denser oceanic crust subducts under a lighter continental crust. as the oceanic crust melts into the mantle, it creates gas pockets and lots of pressure which collects in magma chambers near the surface of the crust. as the pressure builds, the magma may be forced out of vents in the crust, causing violent and infrequent eruptions of thicker magma. this magma travels slowly due to its high silica content so travels shorter distances before setting, creating taller and steeper sloped volcanoes. some eruptions may be pyroclastic flows (flows of ash, hot steam and rocks) therefore composite volcanoes are made up of layers of both lava and ash.
Describe shield volcanoes:
Shield volcanoes occur at constructive plate boundaries where the tectonic plates are diverging from another. this causes the magma from the mantle to erupt out from the gap, this magma is more liquid, so it erupts frequently and spreads quickly across the land forming thinner layers. its gas bubbles are able to easily expand so they erupt gently with no explosions. this makes these volcanoes low and gently sloping.
Explain how volcanic eruptions occur at destructive and constructive plate boundaries:
at destructive plate boundaries, the denser heavier oceanic crust subducts beneath the lighter less dense continental crust into the mantle. as the oceanic crust subducts into the mantle it melts into magma, creating pressure as gases and magma build up. this collects into a magma chamber beneath the surface and rises through cracks in the crust called vents. the magma erupts out of the curst as lava forming a volcano.
in constructive margins, magma rises through the gap -as lava- created between the tectonic plates as they move apart from each other, creating a volcano.
Lahars
Lahars are fast moving flows of mud made out of settled ash on a volcano which can be triggered by heavy rainfall events. as the layers of ash receive the rain, they become unstable and can collapse, sending flows down the volcano at high speeds, often picking up debris on the way carrying them for 10’s of miles.
Pyroclastic flows
these are flows of hot steam, ash and rocks that avalanche down a volcano.
volcanoes
openings in the crust allow hot magma, ash and gases to escape from the mantle
earthquakes
short sudden intense shocks periods that are ground shaking.
they are caused by the pressure that builds up between two plate margins that are passing each other (at conservative boundaries). as they pass each other, they overcome friction which builds their pressure. eventually, they will jerk past each other sending shocks and/or seismic waves through the crust from the focus to an epicentre on the crust. these vibrations are an earthquakes.
Where is Haiti?
Haiti is an island country located in Hispaniola, west of the Dominican Republic in the Caribbean. it sits on the conservative fault line between the Caribbean and North American plate resulting in the 2010 earthquake of a 7.0 magnitude.
Why was Haiti more heavily affected by the earthquake than Christchurch’s 2011 earthquake?
though Christchurch’s focus was shallower and its epicentre was nearer to the city, it experienced less severe impacts because in Haiti…
- 86% of the population live in slum conditions, whose housing was improper and underdeveloped to withstand earthquakes, hence many collapsed leaving people homeless and jobless.
- it had a long history of ineffective and unstable governance, therefore the responses after the earthquake weren’t organised enough leading to slow recovery.
- it is the poorest country in the western hemisphere, with 70% living under $2 a day, this means that funding the recovery was difficult as the country couldn’t afford to implement better infrastructure, making it vulnerable to future events.
compare the effects and responses of Haiti and Christchurch
Haiti primary effects - 220,000 died
Christchurch primary effects - 185 died
Haiti secondary effects - 10 months later, they experienced outbreaks of cholera, $8 billion cost
Christchurch secondary effects - school has to close for 2 weeks due to the damages, $28 billion cost
Haiti short term response - 10,000 troops were sent from the USA, however these were sent for defence purposes to tame communities expecting violence, so primary aid wasn’t distributed and unplanned.
Christchurch short term response - government zoned areas to assess the damage and relocated patients from the hospital to surrounding hospitals to allows victims to be cared for immediately.
Haiti long term response - the new development of advanced infrastructure was eventually introduced but was slow, one year after 1million were still homeless.
Christchurch long term response - New Zealand governments supplied temporary housing and 10,000 affordable houses were constructed.
Typhoon Haiyan:
Typhoon Haiyan is a magnitude 5 (Saffir Simpson scale) super typhoon that occurred in central Philippines in 2013, hitting the small city of Tacloban reaching speeds up to 175 mph and a height of 15m.
Why was Tacloban vulnerable to Typhoon Haiyan?
Typhoons occur between the topics of cancer and Capricorn when oceans reach 27ºC consistently, in the northern hemisphere, they travel in a north westerly direction hence the eastern coast of the Philippines was the first point of contact from the Pacific Ocean. with the Philippines being comprised of many islands, the intensity of the typhoon didn’t weaken by the time it reached Tacloban.
Tacloban is situated in a funnel shaped piece of land which concentrated the typhoon at the tip of the city increasing its strength. 27% of the population lived under $2 per day having a GDP of $4700 per capita.
effects and impacts of typhoon haiyan:
strong winds and 400mm of rainfall damaged buildings and fishing boats and destroyed crops, resulting in 6 million people losing their sources of incomes being a agricultural city. due to the saline water from the storm, recovering fertile agricultural land was hard therefore took a toll to their economy. as a short term response, the US sent helicopters such as the George Washington to distribute aid and help with search and rescue missions, and to help the recovery of the city, ‘Cash for Work’ programs meant that locals could be paid and earn an income for cleaning up the rubble, enabling them to return to a somewhat form of normality with the help of OXFAM who supplied fishing boats to help recover their fisheries.
What are the 6 types of weather hazards in the uk?
- strong winds
- heavy rainfall
- droughts
- floods
- heat waves
- snow and ice
Describe the location of the Somerset Levels and why they were vulnerable to flooding:
The Somerset Levels are located in the county of Somerset, in the south east of England which with the Somerset Moors, form an extensive low-lying plain bordered by the Bristol Channel and the Quantock and Mendip Hills. the area is drained by the Tone and Parrett rivers into the Severn Estuary.
it experienced flooding in the winter of 2014 due to the increased precipitation it has experienced over the years, receiving 100mm more rainfall than average between January and February, causing the soil to become saturated. Further more, heavy rainfall and storm surges from the Bristol channel have caused the tides to push fresh water in river back towards the wetlands, making it unable to drain out the rivers discharge. Additionally, the rivers haven’t been dredged for the past 20 years so their bankfull capacities have reduced significantly.
What were the social impacts of the Somerset flood?
Villages such as Moorland were cut off, meaning local livelihood became harder to continue especially accessing school, disrupting education.
residents had to move into temporary accommodation for several months
What were the economic impacts of the Somerset flood?
over 14,000 hectares of agricultural land was under water for 3-4 weeks with 1,000 livestock being evacuated, it caused the loss of local livelihood, many businesses saw a loss of £1.2 million in business.
What were the environmental impacts of the Somerset flood?
stagnant water had to be collected for months to be reoxygenated before being released into rivers again, this stagnant water made the land toxic and unproductive as the soil became infertile due to the lack of nutrients.
What were immediate responses to the Somerset floods?
rescue boats were dispatched to help stranded people access aid and resources
the Environment Agency installed giant pumps from the Netherlands to lower water levels.
What were long term responses to the Somerset floods?
in march of 2014, 8 km of the River Tone and Parrett were dredged to increase its bankfull capacity, and will be dredged regularly to ensure it can contain excessive amounts of precipitation.
A £100 million 20-year flood action plan is being drawn up to reduce the risk of flooding, enforcing vulnerable communities with flood defences to reduce the severity of damage.
What is the difference between global warming and climate change ?
Global warming refers to the average increase in the earth’s temperature, whereas climate change refers to the overall change in the global changes in temperature, precipitation, seasons and winds.
How are temperature records evidence for climate change
Temperatures can be measured using a thermometer, with the most reliable temperatures being recorded from 1910 in the UK, however, harvest dates and newspaper weather reports also extends our knowledge of climate change.
How are ice and sediment cores evidence for climate change
Ice cores can be extracted by drilling deep down into ice sheets and mountain glaciers and analysing the molecules and air bubbles trapped in the ice, which each year, a new layer of ice is formed. in these air bubbles, scientists can analyse the different atmospheric gasses such as CO2 that were present at the time, tracking the layer back thousands of years and theorising the temperature. they can then present the data to show interglacial and glacial periods.
How are warning signs from nature evidence for climate change
scientists are observing the mannerisms of organisms and how they react to their habitats changing, for example, by monitoring polar bears, they discovered that due to the ice sheets melting earlier, due to increasing temperatures during hunting season, polar bears have been interacting with humans more by scavenging for food in towns.
How are extreme weather events evidence for climate change
scientists are comparing the most recent extreme weather events such as tropical storms, droughts, floods, heat waves, etc to the weather reports from the past, seeing that the weather has become unusual, unpredictable, more intense and frequent.
How is the Keeling curve evidence for climate change
scientists are measuring the amount of CO2 in the atmosphere at the Mauna Loa Observatory in Hawaii on a regular basis and plotting their data on a graph, showing that CO2 levels are increasing rapidly. they predict that levels could be even higher closer to human activity (industry and settlements) which links climate change and the greenhouse effect to humans.
How are glaciers and ice sheets retreating evidence for climate change
glaciers retreat when less snow is being input than what is being output (melting), due to the higher temperatures, new snow has been melting from the glaciers and is unable to remain to be compressed into more permanent ice, this causes glaciers to retreat and the amount that are and the rate they are retreating is increasing. ice sheets are also melting for this reason which can contribute towards higher sea levels especially when the ice sheets sit on land such as Antartica and Greenland.
How is pollen analysis evidence for climate change
scientists can extract pollen and analyse them from the bottom of lakes and pet bogs. the pollen represents the different plants that had existed and since scientists have an idea of the conditions which they grow, we can see that similar species exist now, linking our climate to that of a warmer time.
How are tree rings evidence for climate change
scientists can take cross sections of a tree and count how old it is, as each layer is gown per year, with the thickest layers being grown in warmer and humid conditions.
What are the different evidences for climate change? (8)
- extreme weather
- ice and sediment cores
- glaciers and ice sheets melting
- natures warning signs
- pollen analysis
- temperature records
- tree rings
- the Keeling curve.
What are the natural causes of climate change?
- solar radiation (sun spot theory)
- volcanic activity
- orbital changes
Solar activity (Sun spot theory) as a natural cause of climate change:
climate change can be caused by the sun’s solar activity, known as the sun spot theory, which varies the amount of solar energy the sun outputs. the more sunspots there are the more radiation is received on earth as it means the sun is more active, causing higher temperatures, though this doesn’t effect the climate as much.
Orbital motion as a natural cause of climate change:
orbit motion effects how much of the sun’s radiation is received on earth due to three factors: precession, eccentricity and axis tilt.
- precession is the earth wobbling during its obit, which explains why some latitudes experience longer and shorter days in certain times of the year.
- eccentricity is when the earth morphs from a circular to an elliptical orbit around the sun, this explains the colder weather in winter and warmer weather in summer as the further away from the sun, the less energy it receives.
- axis tilt is due to the fact the the earth spins on an angle, which brings about night and day.
Volcanic activity as a natural cause of climate change:
When volcanoes erupt they eject particulates and gases into the atmosphere like sulphur. this can form a layer in our atmosphere which reflects radiation from the sun away from our atmosphere, preventing any from entering causing the climate to cool temporarily.
What are the human causes of climate change:?
Fossil fuels as a human cause of climate change:
Fossil fuels are finite resources (coal, oil and natural gas) derived from detritus formed over millions of years. it is increasing because our population is rising, so there is a higher demand for energy and manufacturing materials from the combustion of fossil fuels which releases CO2 into the atmosphere. this causes climate change because the higher the concentration of these greenhouse gases the more solar radiation is prevented from escaping into space, so the earth retains its heat causing higher temperatures.
Deforestation as a human cause of climate change:
Deforestation is the permanent removal of trees from an area to make space for housing, urbanisation and agriculture. it is increasing because our growing population requires more space and resources to survive, especially with our standard of living increasing. we need more land for accommodations, cattle ranching and we extract timber and other vegetations for medicine from them. this is causing climate change because trees act as carbon sinks, who absorb CO2 from our atmosphere and store it inside. by cutting them down, not only do we reduce this but we also release CO2 into the air when we burn it, so less radiation is lost from our atmosphere causing temps to increase.
Agriculture as a human cause of climate change:
Agriculture is the harvesting of animals, plants and fungi for food, fuel, medicine and other resources which is increasing with our growing demand for products. as our population increases our standard of living increases so our meat consumption also increases, this not only releases CO2 as we deforest areas for land but also releases methane. This causes climate change due trout anthropogenic emissions
What are the social effects of climate change:
- Desertification of crop fields and the flooding of low-lying agricultural land causes crop yields to deplete, which result in the population having food insecurity and are at greater risk of malnourishment, ill-health and death from starvation.
- Populations such as the Sahel region have resorted to migrating away from drought areas due to the risk of starvation.
- 80 million people are at risk in low-lying areas prone to flooding, 17 million in Bangladesh who with its increasing population puts more people are risk and flood defences under more pressure
- extreme heat waves experience in Europe have caused premature deaths of the elderly and the young, due to the 2003 heat wave, England and Wales had 2,000 extra deaths.
- waterborne diseases may spread to other parts of the world as vectors such as mosquitoes transmit communicable diseases such as malaria which don’t have a cure.
What are the economic effects of climate change:
- If lower latitudes are unable to be productive with a good crop yield, it could affect the world market of food, making prices increase as certain foods become harder to grow.
- if droughts become more common due to the increasing temperatures, less water will be available for irrigation of crops so there will be lower crop yields to be exported for money.
- tourism may be impacted severely, as resorts who are focused around skiing become less attractive as the lack of snow no longer makes tourists visit.
What are the environmental effects of climate change:
- desertification due to the high temperatures causing droughts in countries makes the land arid and unable to sustain vegetation and a biodiverse biome
- flooding may become more common as the higher temperatures cause water in oceans to expand
- many species have migrated to cooler climates, whereas those who are land-based may go extinct due to being unable to adapt quickly to their changing environment.
what are mitigation and adaptation strategies:
mitigation strategies aim to reduce the impacts of climate change whereas adaptation strategies aim to respond and adjusting life around it.
A PEE paragraph about the mitigation strategy: alternative energy sources:
Alternative energy sources aim to reduce the CO2 emissions caused by the combustion of fossil fuels (coal, oil, and natural gas) with renewable energy sources such as tidal, solar and geothermal. this reduces the greenhouse emissions significantly and is sustainable for future generations however it is more expensive than fossil fuel energy and can be unreliable due to the weather.
A PEE paragraph about the mitigation strategy: carbon capture and storage (CCS)
carbon capture and storage aims to convert gaseous CO2 into supercritical CO2 in liquid form to be injected into sedimentary rocks to be stored. this is good as it takes away majority of CO2 produced by industry and power stations from being released however, it isn’t certain that the CO2 stored in the rocks would be a long-term solution, is expensive and it doesn’t reduce CO2 being produced in the first place.
A PEE paragraph about the mitigation strategy: afforestation
by planting more trees, these trees will act as a carbon sink, absorbing and storing the CO2 in the atmosphere through photosynthesis, which also produces a cooling effect as it produces water vapour, which is a greenhouse gas which helps prevent more solar radiation from entering the atmosphere however, it can be expensive, takes up lots of land and time to be effective.
A PEE paragraph about the mitigation strategy: international agreements
world summits enable governments to collaborate on global strategies of climate change, helping to internationally tackle it together rather than alone. it can set legal binding obligations to industrialised countries to reduce their CO2 emissions for the benefit for everyone’s future however, these agreements can be seen as promises and aren’t as strict as they should be.
A PEE paragraph about the adaptation strategy regarding agriculture:
Agriculture can be heavily impacted by climate change due to the changing rainfall and higher temperatures which impede on their productivity. to combat this, farmers can start growing different crops which are more suitable to the changing environments to ensure they have a feasible yield. some may also grow genetically modified crops where scientists have adapted the genetics of a crops to better adapt to the changing conditions such as allowing them to grow in drier conditions. other strategies such as conserving water using dams and reservoirs also ensures that farmers have enough water to irrigate their fields in droughts or draining areas in times of floods heavy rain. this reduces the risk of food shortages globally as people are still able to grow enough food yearly to export and to live on, reducing the chances of ill-health, malnourishment and starvation.
A PEE paragraph about the adaptation strategy regarding water supply:
climate change has also caused many droughts and floods. in droughts where water becomes scarce, people must conserve water and maximise its usage. to combat this, infrastructure such as pipelines, dams and reservoirs can be used to store water to be used in irrigation or to transfer water from areas of surplus to deficit. additionally, we can educate on reducing, reusing and recycling grey water to maximise the potable water available. we can also collect rainwater to use for other uses. this reduces the impact of climate change as areas in water deficits can receive the water they need to support their populations, for example irrigating fields and doing industry such as agriculture, reducing food insecurity .
A PEE paragraph about the adaptation strategy regarding rising sea levels:
due to the higher temperatures causing water in oceans to expand, putting low-lying areas at risk of flooding and storms, sea defences may be installed to reduce the need of evacuation, economic cost to recovery and the environmental toll of excessive rainfall (eroding nutrients from the soil). additionally, people can resettle in higher altitudes to reduce property destruction as sea levels could rise by 82mm by 2100. this reduces the impact of climate change as less people are needed to evacuate from certain areas and reduces the stress as the aftermath (displacement and the economic cost).
