Flashcards in 1A: The Challenge of Natural Hazards Deck (109):
what is the definition of a natural hazard?
an extreme natural event that has the capacity to cause damage to people and property
give two examples of a geophysical/geological hazard?
earthquake and tsunami
give two examples of a hydrological hazard?
flooding and landslide
give two examples of a meteorological hazard?
tropical storm and tropical cyclone
give two examples of a climatological hazard?
drought and wildfire
give two examples of a biological hazard?
disease and insect infestation
what is the definition of hazard risk?
the chance or probability of being affected by a natural event
what factors increase the risk from natural hazards?
1) urbanization (higher concentration of people)
2) poverty (poor infrastructure + live in dangerous areas)
3) farming (low lying land means on flood plane)
4) climate change (some parts may become wetter, some drier and increased intensity of storms)
what is the theory of plate tectonics?
the crust is made up of tectonic plates which are in constant motion. earthquakes and volcanoes are more likely to occur at plate boundaries.
what are the four concentric layers of the earth?
inner core, outer core, mantle and crust
what is a tectonic plate?
broken section of the earth's crust
what is a plate margin?
where two tectonic plates meet (boundary)
what are the two types of the earth's crust?
oceanic and continental
is oceanic or continental crust denser?
is oceanic or continental crust older?
what happens to the pressure as you go deeper inside the earth?
is the core solid or liquid?
why is the core solid?
very high pressure keeps it in solid state
what does the lithosphere comprise of?
the crust and the upper mantel
what is continental drift?
when continents move apart
why do tectonic plates move?
1) heat from the core causes convection currents in the mantel
2) these cause the crusts, which float on the top of the mantel, either towards or apart from each other
what is the world distribution of tectonic activity?
1) Along plate boundaries.
2) On the edge of continents.
3) Around the edge of the Pacific. (Pacific Ring of Fire)
describe the process at constructive plate margins
1) plates more apart due to convection currents
2) as plates move apart magma rises up from the mantle due to convection, leading to pressure and doming of the crust.
3) as magma continues to build up eventually volcanic islands form as they break the surface of the ocean
4) when this magma breaks through the overlying crust earthquakes occur
5) rising magma gently flows out and forms shield volcanoes which are less explosive
6) lava cools and solidifies to form ridges
what is an example of a constructive plate margin?
Iceland and Mid-Atlantic ridge
what are the features of a constructive plate margin?
1) generally gentle volcanic eruptions
2) broad and flat shield volcanoes
3) occasionally small earthquake
describe the process at destructive plate margins
1) plates move together due to convection currents
2) the oceanic dense plate sub ducts beneath the less dense continental plate
3) as the oceanic plate moves downwards it melts due to the high temperature and friction (this friction causes strong earthquakes)
4) the newly-formed magma is lighter than the mantle as it is mixed with seawater and forces its way to the surface to form steep sided composite volcanoes
5) rising magma contains gas and is highly pressurized leading to explosive eruptions
what is an example of a destructive plate margin?
Nazca and South American plate
what are the features of a destructive plate margin?
1) explosive volcanic eruptions
2) deep earthquakes
describe the process at conservative plate margins
1. plates move in different directions or at different speeds to one another
2. plates stick or jam together and huge amounts of pressure build up
3. pressure releases and the plates move suddenly causing a violent earthquake
what is an examples of a conservative plate margin?
San Andreas fault in California
what are the feature of a conservative plate margin?
1) powerful earthquakes
2) no volcanic eruption as there is no magma
describe the process of earthquakes
1. two plates become locked causing friction to build up
2. the pressure will eventually be released, triggering the plates to move into a new position
3. this movement causes energy in the form of seismic waves, to travel from the focus towards the epicentre
4. the crust vibrates triggering an earthquake
what is the epicenter of an earthquake?
the point directly above the focus, where the seismic waves reach first
what is the focus of an earthquake?
the point at which pressure is released
why do people continue to live near tectonic hazards?
1) People living in poverty ridden areas have more important things to think about like food, money, security and family.
2) Plate margins often coincide with very favourable areas for settlement, such as coastal areas where ports have developed.
3) Fault lines associated with earthquakes allow water supplies to reach the surface. This is important in dry desert regions.
4) Better building design can withstand earthquakes so people feel less at risk.
5) Volcanoes can bring benefits such as fertile soils, rocks for building, rich mineral deposits, hot water and geothermal energy.
6) More effective monitoring of volcanoes and tsunamis waves enable people to receive warnings and evacuate before events happen
how can monitoring and prediction reduce the risk of tectonic hazards?
1) Seismometers measure earth movement
2) Radon gas sensor (radon gas is released when plates move so this finds that)
3) Water table level (water levels fluctuate before an earthquake)
4) Satellite surveying (tracks changes in the earth’s surface)
5) Laser reflector (surveys movement across fault lines)
how can planning reduce the risk of tectonic hazards?
1) Avoid building in at risk areas
2) Training for emergency services and planned evacuation routes and drills
how can protection reduce the risk of tectonic hazards?
1) Building earthquake-resistant buildings e.g. Automatic shut offs for gas and electricity.
2) Raising public awareness
3) Improving earthquake prediction
what is the global atmospheric circulation model?
a number of circular air movements called cells joined together to form the overall circulation of the earth's atmosphere (powered by warm air rising)
What happens to air at the equator?
At the equator, the sun’s rays are most concentrated. This means it is hotter so it rises.
what is the cell 30° north and south of the Equator?
The Hadley cell
what happened to air 30° north and south of the Equator?
The air sinks under high pressure. High pressure weather brings dry and clear skies.
what is the cell above the Hadley cell?
The Ferrel cell
explain the convection current in the Polar cell
1) Air at the polar latitudes is colder and denser so the air sinks towards the ground surface under high pressure conditions.
2) This air flows towards the Equator.
3) The air warms as it reaches about 60°and again rises under low pressure conditions.
when does low pressure occur?
when there is hot less dense air
when does high pressure occur?
when there is cold dense air
what is the corrolis effect?
the impact of the earth's rotation of global wind patterns. the anticlockwise rotation of the earth deflects winds to the right in the northern hemisphere and to the left in the southern hemisphere
why do surface winds occur?
Winds on the surface of the Earth are experienced as air moves from high to low pressure belts in the convection cells
why is it often cloudy and wet in the UK?
1) The UK is located about 55°north just below the 60° line of latitude putting the UK close the boundary of Polar air moving down from the north and warm sub-tropical air moving up from the south.
2) The boundary between these two cold and warm air masses is unstable.
3) Here there is rising air and low-pressure belts (the sub polar low) on the ground.
4) Rising air cools condenses and forms clouds and rain.
is the equator in a low or high pressure belt?
low pressure belt
what is the distribution of tropical storms?
1) occur in low latitudes between 5° and 30° north and south of the equator (in the tropics)
2) occur above seas/oceans
3) they don’t occur on the equator
rarely occur in the south atlantic
why don't tropical storms form on the equator?
because there is not enough spin from the rotation of the Earth
what temperature does the ocean have to be in order for tropical storms to form?
how do tropical storms form?
1) The sun’s rays heats large areas of the ocean, causing warm, moist air to rise over the particular spots
2) Once the temperature is 27⁰, the rising warm moist air leads to a low pressure. This eventually turns into a thunderstorm. This causes air to be sucked in from the trade winds.
3) With trade winds blowing in the opposite direction and the rotation of earth involved (Coriolis effect), the thunderstorm will eventually start to spin.
4) When the storm begins to spin faster than 74mph, a tropical storm (such as a hurricane) is officially born.
5) With the tropical storm growing in power, more cool air sinks in the centre of the storm, creating calm, clear condition called the eye of the storm.
6) When the tropical storm hits land, it loses its energy source (the warm ocean) and it begins to lose strength.
how may climate change impact the distribution of tropical storms?
The location of tropical is not expected to change significantly, but there may be more in areas such as the South Atlantic and parts of the subtropics as sea surface temperatures increase.
how may climate change impact the frequency of tropical storms?
The overall frequency of tropical storms is expected to remain the same or decrease. However, the frequency of category 4 and 5 storms (strongest) is expected to increase, whilst the frequency of 1-3 storms (weaker) is expected to decrease.
how may climate change affect the intensity of tropical storms?
Since 1970s the number of the most severe category 4 or 5 tropical storms has increased. Every 1-degree Celsius increase in sea surface temperatures will mean a 3-5% increase in wind speed.
how can monitoring reduce the effects of tropical storms?
1) Satellites monitor cloud patterns associated with tropical storms.
2) NASA monitor weather patterns using unmanned drones called Global Hawk.
how can prediction reduce the effects of tropical storms?
1) Supercomputers give 5 days’ warning and predict a location within 400km.
2) Track forecast cones plot the tropical storms path. Approx. 70% occur within the cone.
how can protection reduce the effects of tropical storms?
1) Reinforce buildings – hurricane shutters on windows and doors.
2) Develop coastal flood defences.
3) Create ‘no-build zones’ in low lying areas
how can planning reduce the effects of tropical storms?
1) Those living where it will hit can prepare disaster supply kits and ensure their car is fully fuelled.
2) People should know where evacuation centres are.
3) Emergency drills
how do weather recording provided evidence for climate change?
An increase in the average surface air temperature by 1⁰C over the past 100 years
The warmest ocean temperatures since 1850
how do shrinking glaciers/ice sheets provide evidence for climate change?
Arctic sea ice has thinned by 65% since 1975, showing warmer temperatures causing ice to melt
how do rising sea levels provide evidence of climate change?
A 19 cm rise in sea levels since 1900, due to thermal expansion and land ice melting.
how do ice cores provide evidence of climate change?
show changes in concentration of carbon dioxide and oxygen (dating back 800,000 years). changes in oxygen can be inferred from the abundance of oxygen isotopes (ratio of oxygen-16 to oxygen-18). show how temperature has increased since the Quaternary period.
how can tree rings (dendrochronology) provide convincing evidence for climate change?
rings are wider during cool, wet years showing how the climate has changed
how can volcanic activity affect world temperatures?
volcanic eruptions produce ash and sulfur dioxide, which forms a layer around the earth. these volcanic aerosols reflect sunlight away, temporarily reducing temperature.
how can orbital geometry affect world temperatures?
the sun's energy on the earth's surface changes as the earth's orbit is elliptical, its axis is tilted and the earth isn't spherical
how can solar output affect world temperatures?
the number of sunspots changes and higher numbers of sunspots means the sun is more active and releasing more solar energy towards earth
how long are sunspot cycles?
how does the burning of fossil fuels affect world temperatures?
burning fossil fuels releases greenhouse gases (primarily carbon dioxide) which increases world temperatures
how does agriculture affect world temperatures?
leads to deforestation and emits greenhouse gases (e.g. methane is released from rice cultivation)
describe the greenhouse effect
greenhouse gases trap infrared radiation stopping it escaping to outer space and allowing the earth to cool
how does deforestation affect world temperatures?
deforestation increases the amount of carbon dioxide in the atmosphere as less photosynthesis occurs
what are the effects of climate change on people?
1) Increased disease eg. skin cancer and heat stroke
2) Winter deaths decrease with milder winters
3) Crop yields affected by up to 12% in South America but will increase in Northern Europe but will need more irrigation
4) Less ice in Arctic Ocean increases shipping and extraction of oil and gas reserves
5) Droughts reduce food and water supply in sub-Saharan Africa. Water scarcity in South and South East UK
6) Increased flood risk. 70% of Asia is at risk of increased flooding
7) Declining fish in some areas affect diet and jobs
Increased extreme weather
8) Skiing industry in Alps threatened.
what are the effects of climate change on the environment?
1) Increased drought in Mediterranean region
2) Lower rainfall causes food shortages for orangutans in Borneo and Indonesia
3) Sea level rise leads to flooding and coastal erosion
4) Ice melts threaten habitats of polar bears
5) Warmer rivers affect marine wildlife
6) Forests in n America may experience more pests, disease and forest fires
7) Coral bleaching and decline in biodiversity such as the Great Barrier Reef (Australia)
how can we adapt to climate change?
1) moving production to another location due to changing temperatures and extreme weather
2) increasing irrigation in areas due to changing precipitation
3) changing the crops grown and the times of year they are planted
4) sea defences
how have people in Peru adapted to climate change?
potato park in Peru started to grow crops at higher altitudes
how have people in India adapted to climate change?
1) Artificial glaciers are being constructed to supply water to villages in Ladakh, India.
2) Water is collected in winter through a system of diversion canals and embankments and it freezes.
3) When the ‘glacier’ melts in spring it will provide water for the local villages. .
how can alternative energy provision mitigate climate change?
renewable energy sources do not emit large amounts of carbon dioxide
how can carbon capture and storage mitigate climate change?
1) It is possible to capture up to 90% of the CO₂ that
would otherwise enter the atmosphere.
2) Once CO₂ is captured, the carbon gas is compressed and transported by pipeline to an injection well.
3) It is injected as a liquid into the ground to be stored in suitable geological reservoirs such as sedimentary rock as this prevents it from escaping.
how can planting trees mitigate climate change?
1) Trees act as carbon sinks, removing CO₂ from the atmosphere by the process of photosynthesis.
2) They also release moisture into the atmosphere. This has a cooling effect by producing more cloud, reducing incoming solar radiation.
give an example of an international agreement which has mitigated climate change
Paris Agreement 2015
195 countries adopted the first ever universal and legally binding global climate deal which agreed to:
1) peak greenhouse gas emissions as soon as possible and achieve a balance between sources and sinks of greenhouse gases in the second half of this century (2050-2100).
2) keep global temperature increase below 2°C and limited to 1.5°C above pre-industrial levels.
3) review progress every 5 years.
4) give $100 billion a year to support climate change initiatives in developing countries by 2020, with further finance in the future.
when was the Christchurch Earthquake?
what was the magnitude of the Christchurch Earthquake?
what were the primary effects of the Christchurch earthquake?
1) 185 people died
2) Over 50% of central buildings were damaged/destroyed
3) 200,000 homes affected
what were the secondary effects of the Christchurch earthquake?
1) 80% of city without electricity
2) 13 schools closed and 18 merged meaning sharing classrooms
3) Many businesses in CBD out of action
4) Christchurch could no longer host the Rugby World Cup
what were the immediate responses to the Christchurch earthquake?
1) Chemical toilets provided for 30,000
2) Areas were zoned to classify damage
3) Some international aid
what were the long term responses to the Christchurch earthquake?
1) Gov to spend NZ$1bn in the next 10 years to renew education system
2) Paid NZ$900 million in building claims in first 6 months
3) 80% of roads were repaired
4) Water and sewage restored by August
when was the Haiti Earthquake?
what was the magnitude of the Haiti Earthquake?
what were the primary effects of the Haiti Earthquake?
1) 316,000 people died
2) 250,000 homes were destroyed/damaged
3) Over 1 million people left homeless
4) Transport links (e.g. docks and roads) destroyed
5) 19 million cubic meters of rubble
what were the secondary effects of the Haiti Earthquake?
1) Hospitals and Morgues became full so bodies piled up on the streets
2) Diseases such as cholera became an issue
3) Difficult to get aid because of transport issues
5) 20% of people lost their jobs
what were the immediate responses to the Haiti Earthquake?
1) $100 million in aid from USA
2) $330 million in aid from EU
3) 800,000 people in aid camps
4) 1.3 million put in homeless shelters
5) 4.3 million provided with food rations
what were the long term responses to the Haiti Earthquake?
1) 98% of rubble remained uncleared 6 months post-earthquake
2) 1 million without houses after a year
3) Water and sanitation supplied to 1.7 million people
4) Temporary schools
when was Typhoon Haiyan?
what category was Typhoon Haiyan?
what were the primary effects of Typhoon Haiyan?
1) 6,300 people killed
2) Over 600,000 people displaced damaged
3) 90% of buildings in Tacloban City were destroyed
4) Strong winds damaged power lines and crops
5) Over 40mm of rain caused widespread flooding
6) 30,000 fishing boats destroyed
what were the secondary effects of Typhoon Haiyan?
1) 6 million people lost source of income
2) Only 20% of the people in need of aid in Tacloban received it as landslides blacked roads
4) Rise in crime due to desperation and low police presence (only 100 of 1300 police reported for duty)
what were the immediate responses to Typhoon Haiyan?
1) $780 million from UN fundraising appeal
2) $500 million from foreign nations
3) Save the children helped build tent schools
4) Over 1200 evacuation centers set up to help homeless
5) Field hospitals set up
what were the long term responses to Typhoon Haiyan?
1) ‘Cash for work’ scheme paid people to clear debris and rebuild the city
2) Aid agencies (i.e. Oxfam) supported replacement of fishing boats
3) Gov implemented soft engineering schemes (e.g. mangrove plantations) to reduce impact of waves
4) Rebuild roads, bridges and airport
when were the Cumbria floods?
what caused the Cumbria floods?
1) Record rainfall – Cumbria had already received a month’s worth of average rainfall before the 17th November
2) the soil was saturated. Rainfall flowed down into the rivers (River Derwent was 10m wider than normal and flowing 25x higher)
what were the social impacts of the Cumbria floods?
1) Police officer killed when bridge collapsed
2) 1500 homes flooded
3) River water contaminated with sewage (health risk)
what were the economic impacts of the Cumbria floods?
1) Debris transported by river destroyed 6 important regional bridges
2) Many businesses closed and did not reopen for a long time
3) Regional economy lost money due to decline in tourism
what were the environmental impacts of the Cumbria floods?
1) Water erosion by the River Derwent triggered landslides along its banks
2) Hundreds of trees tore loose and carried away, damaging habitats
what management strategies have been employed in response to the Cumbria floods?
1) New flood defenses built at a cost of ₤4.5 million (Mobile wall built which rises when needed and can disappear so as not to disrupt tourism etc.)
2) Flood warning systems improved.
Describe the features of a tropical storm
1) circular shaped eye surrounded by a vortex of clouds
2) could spins clockwise or anti-clockwise towards the centre