The Challenge of Natural Hazards Flashcards
Define natural hazard
A natural event that posses a risk to people and property
What are the two types of natural hazard?
- Geological
- Meterological
What is a geological hazard?
Hazards caused by land and tectonic processes
Examples of geological hazards [4]
- Volcanoes
- Earthquakes
- Landslides
- Avalanches
What is a meterological hazard?
A hazard caused by weather and climate
Examples of meterological hazards [2]
- Tropical storms
- Extreme weather
Define hazard risk
The probability of people being affected by a hazard in a particular area
What 3 things affect hazard risk?
- Capacity to cope
- Population density
- Nature of hazard
How does capacity to cope affect hazard risk? [2]
- The better a population can cope with an extreme event, the lower the risk of them being severely affected
- e.g. HICs are able to cope with flooding because they can afford to build flood defences
How does population density affect hazard risk? [2]
- The more people there are in an area exposed to a hazard, the greater probability that they will be affected
- e.g. an area with a large population density on a floodplain would be very vulnerable to flooding
How does the type of hazard affect hazard risk? [2 examples]
- Tropical storms can be predicted and monitored, giving people time to evacuate
- Earthquakes happen very suddenly, with little warning, so it’s harder to protect people
How does the frequency of a hazard affect hazard risk?
Natural hazards that occur more often may carry a higher risk
How does the magnitude of a hazard affect hazard risk?
More severe natural hazards tend to have greater effects
What are the 2 types of crust that tectonic plates are made from?
- Continental
- Oceanic
Describe continental crust:
i) thickness
ii) density
i) Thicker (30 - 50 km)
ii) Less dense
Describe oceanic crust:
i) thickness
ii) density
i) Thinner (5 - 10 km)
ii) More dense
What moves tectonic plates in the mantle?
Convection currents
Describe what happens at a destructive plate boundary (2 diff. plates) [2]
- Oceanic and continental plates move towards each other
- Denser oceanic plate subducted and destroyed
Describe what happens at a destructive plate boundary [2]
- Two continetal plates meet
- Ground is folded upwards
What is created at destructive plate boundaries (2 diff. plates)? [2]
- Volcanoes
- Ocean trenches
What is created at destructive plate boundaries?
Fold mountains
Describe what happens at a constructive plate boundary [2]
- Two plates moving away from each other
- Magma rises from the mantle, creating new crust
What is created at a constructive plate boundary?
Ridges
Describe what happens at a conservative plate boundary [2]
- Plates are moving sideways past each other
- OR plates are moving in same direction but at different speeds
What can occur at conservative plate boundaries?
Earthquakes
What plate boundaries do volcanoes occur at? [2]
- Destructive
- Constructive
Explain how volcanoes form at destructive plate margins [3]
- Denser oceanic plate moves down into the mantle and melts
- A pool of magma forms, which then rises through cracks in the crust called vents
- The magma erupts, forming a volcano
Explain how volcanoes form at constructive plate margins [2]
- Magma rises up into the gap, created by the plates moving apart
- Forming a volcano
What plate boundaries do earthquakes occur at? [3]
- Destructive
- Constructive
- Conservative
Explain how earthquakes occur at destructive plate boundaries
Tension builds when one plate gets stuck as it moves past the other
Explain how earthquakes occur at constructive plate boundaries
Tension builds along cracks in the plates as they move away from each other
Explain how earthquakes occur at conservative plate boundaries
Tension builds up when plates that are grinding past each other get stuck
What is the focus of an earthquake?
The point in the earth where the earthquake starts
What is the epicentre of an earthquake?
The point on the Earth’s surface straight above the focus
What are the 2 scales that measure earthquakes?
- Richter scale
- Mercalli scale
What does the Richter scale measure?
Magnitude of an earthquake
What does the Mercalli scale measure?
Damage caused by an earthquake
Why do people continue to live in areas at risk from tectonic hazards? [5]
- Family ties
- Too poor to move
- Farming
- Mining
- Tourism
How can earthquakes be monitored?
Use seismometers and lasers to monitor earth movements
How can volcanic eruptions be monitored?
Scientists can monitor tell-tale signs (e.g. tiny earthquakes, escaping gas and changes in volcano shape)
Protection from earthquakes [3]
- Buildings built with concrete that absorbs shock waves
- Bridges strengthened withs steel frames
- Automatic shutters and shut-off switches
Protection from volcanoes [2]
- Buildings strengthened - less likely to collapse under weight of ash
- Dig channels and embankments to divert lava away from settlements
Ways to plan for a tectonic hazard [4]
- Emergency services can prepare
- People can be educated on what to do
- Governments can plan evacuation routes
- Supplies can be stockpiled e.g. food, water, blankets
What weather does a high pressure system bring [1] and why [1]
- Dry, settled conditions
- Air sinks, warms up and dries out
What weather does a low pressure system bring [1] and why [1]
- Wet, unsettled conditions
- Water vapour rises, cools, condenses and forms clouds for rainfall
Why does the curvature of the Earth cause some areas to receive more heat radiation than others? [2]
- At higher latitudes, the radiation from the sun is spread over a much larger surface area
- At the equator, the same amount of energy is much more concentrated
Why do the polar regions recieve little radiation from the sun? [2]
- Radiation travels through a greater depth of atmosphere at the poles
- Snow and ice reflect a lot of the sun’s radiation back into space
How does the tilt of the Earth affect how much heat energy the poles receive? [2]
- The polar regions do not see daylight during the winter
- Therefore, the Earth is continually sending out heat into space without any compensating heat back from the sun
Describe what happens in the Hadley cells [4]
- At the equator, warm, less dense air rises
- It rises to around 18km and spreads out underneath the tropopause
- The warm air spreads out towards the poles, cooling and sinking as it moves
- It then descends to the surface and flows back to the equator
Describe what happens in the Polar cells [3]
- Cool, dense air descends in the polar regions
- Air flows at low levels of 60° to 70° north of south
- As air leaves the polar regions, it starts to warm and rise and returns to the poles at high levels
What is the weather like in the Hadley cells [1] and why [1]
- Warm and wet
- Rising air
What is the weather like in the Polar cells [1] and why [1]
- Dry and cold
- Falling air
What are the 3 features of Ferrel cells?
- Not driven by temperature
- These cells flow in the opposite direction, acting like a gear
- Transport heat from the equator to the poles
What is the weather like in the Ferrel cells [1] and why [1]
- Wet and cold
- Rising air but far from equator
Where do tropical storms develop?
Between 5 and 30° north and south of the equator
What conditions do tropical storms need to develop? [3]
- Sea temperatures of 27° or higher
- Low wind sheer
- Sea depth of 60-70 m
Describe the formation of a tropical storm [6]
- Air is heated above the surface of warm tropical oceans
- This warm air rises, drawing more air and large volumes of mositure from the ocean
- This causes strong winds
- Rising air will cool and condense to form tall cumulonimbus clouds
- Low wind shear stops the storm being torn apart
- Storm starts to spin due to the Coriolis effect
Why is the eye of a tropical storm calm?
Cool sinking air creates an area of high pressure, leading to calm, drier conditions
What is a tropical storm steered by?
Trade winds
Why do tropical storms lose strength when they hit land?
Their energy supply from the warm water is cut off
What are the features of the eyewall? [5]
- Spiralling rising air
- Very strong winds
- Storm clouds
- Torrential rain
- Low temperature
What happens on the edges of a tropical storm? [4]
- Wind speed falls
- Clouds become smaller and more scattered
- Rain becomes less intense
- Temperature increases
How will climate change affect the frequency of tropical storms? [3]
- Oceans will stay at 27°C or higher for longer each year
- So there will be a longer period when tropical storms can form
- This may increase the frequency of tropical storms per year
How will climate change affect the distribution of tropical storms? [3]
- The average ocean temperature will rise
- More of the world’s oceans could be above 27°C
- Tropical storms could could form in areas that haven’t experienced them before
How will climate change affect the intensity of tropical storms? [3]
- Higher sea surface temperatures
- Could result in more evaporation and increased cloud formation, so more energy is released
- Could mean storms could become more powerful
How can tropical storms be predicted and monitored? [3]
- Radar
- Satellites
- Aircraft
How does predicting and monitoring tropical storms reduce its effects? [3]
- Gives people more time to evacuate and protect their homes
- Reduces deaths and damage to property
How can a tropical storm be planned for? [3]
- Future developments can avoid high-risk areas
- Governments can plan evacuation routes
- Emergency services can prepare
How does planning for a tropical storm reduce its effects? [2]
- Reduces the time taken to evacuate people
- Reduces deaths
How can areas be protected from tropical storms? [2]
- Buildings can be protected - window pannels, stilts etc
- Flood defences can be built along rivers and coasts
How does protecting areas from a tropical storm reduce its effects? [2]
- Reduces damage to property
- Saves money
What are the impacts of strong winds? [3]
- Damage to properties
- Disrupt transport
- Uprooted trees and debris can injure or kill people
What are the impacts of heavy rainfall? [2]
- Flooding (damage homes, disrupt transport and drown people)
- Recovering from flooding can cost millions
What are the impacts of snow and ice? [3]
- Injuries and deaths due to slipping and cold
- Travel disruption
- Schools and businesses forced to shut
What are the impacts of drought? [2]
- Crop failure due to lack of water
- Hosepipe bans etc introduced
What are the impacts of thunderstorms?
Lightening can cause fires, which damage property, and sometimes kill people
What are the impacts of heat waves? [2]
- Health issues (e.g. heat exhaustion)
- Disruption to travel
What is the evidence that weather in the UK is becoming more extreme (temperature)? [2]
- UK’s 10 warmest years have all occured since 2002
- UK’s 7 coldest temperatures have all occured since 1980
What is the evidence that weather in the UK is becoming more extreme (rainfall)? [2]
- More rainfall records broken between 2010 and 2014 than in any other decade on record
- Decemeber 2015 was the wettest month ever recorded
What is evidence for climate change? [4]
- Ice cores
- Tree rings
- Pollen analysis
- Temperature records
How can ice cores show what temperatures were like?
By analysing the gases trapped in the layers of ice, they can tell the temperature from each year
How can tree rings show what the climate was like?
Scientsists can use the thickness of each ring to work out what the climate was like
How can pollen analysis show that the climate was similar to today? [3]
- Pollen from plants gets preserved in sediment
- Scientists can identify and date preserved pollen to show which species were living at the time
- Scientists know the conditions plants live in now, so preserved pollen from similar plants shows climate conditions were similar
What are the 3 possible natural causes of climate change?
- Orbital changes
- Volcanic activity
- Solar output
What could have orbital changes caused?
Glacial and interglacial cycles of the Quaternary period
How can volcanic activity cause climate change? [3]
- Major volcanic eruptions eject large quantities of material into the atmosphere
- Some of these particles reflect the sun’s rays back out into space
- This causes the Earth’s surface to cool
How does the Earth’s solar output change?
It changes in short cycles of about 11 years
Describe the greenhouse effect
Greenhouse gases absorb outgoing heat from Earth, so less is lost to space
What are the 4 human causes of climate change?
- Burning fossil fuels
- Cement production
- Farming
- Deforestation
What does mitigating climate change mean?
Reducing the causes of climate change
What are the 4 ways to mitigate climate change?
- Carbon capture
- Planting trees
- Alternative energy production
- International agreements
How does planting trees reduce the amount of CO₂ in the atmosphere? [2]
- Planting trees increases the amount of CO₂ that is absorbed from the atmosphere through photosynthesis
- This reduces the amount of CO₂ in the atmosphere
How does carbon capture stoarge (CCS) reduce the amount of CO₂ in the atmosphere? [2]
- CO₂ is captured and stored underground
- Reduces the amount of CO₂ in the atmosphere
How does alternative energy production reduce the amount of CO₂ in the atmopshere? [2]
- Replacing fossil fuels with nuclear or renewable energy
- Reduces greenhouse gas emissions in atmosphere
What does the Paris Agreement aim to do?
Reduce greenhouse gas emissions and limit global warming
When did the Paris Agreement come into force?
Novemeber 2016
How many parties have signed the Paris Agreement?
195 parties
What does the Paris Agreement encourage developed countries to do?
Help developing countries put mitigation strategies into place
What does adapting to climate change mean?
Responding to the effects of climate change
What are 3 ways to adapt to climate change?
- Changing agricultural systems
- Managing water supply
- Coping with rising sea levels
How can agricultural systems be changed? [2]
- Plant new crop types that are more suited to the new climate of that area
- Biotechnology is being used to create new crop varieties which are more resistant to extreme weather
How can water supply be managed? [2]
- Water meters can be installed to discourage excessive water use
- Rainwater and waste water can be collected and recycled
How are areas coping with rising sea levels? [2]
- Flood barriers being built
- Building houses on stilts/embankments
