P1 SA The Challenge Of Natural Hazards Flashcards
Define natural hazard
A natural event that has a social impact
What are the three types of natural hazard
Atmospheric
Tectonic
Hydrological
What are examples of atmospheric hazards
Rain / snow
Lightning
Drought
Hurricanes
Wind
What is a hydrological hazard
Flooding
What are examples of a tectonic hazard
Volcanoes
Landslides
Mudflows
Avalanches
Earthquakes
What is hazard risk?
The chance or probability of being affected by a natural event
What are the factors affecting hazard risk?
Urbanisation
Poverty
Climate change
Farming
How does urbanisation affect hazard risk?
Over 50% of world pop. live in cities
Some of world’s largest cities are at risk from earthquakes eg Tokyo, Istanbul, LA
Densely populated urban areas are at great risk from natural hazards
How does poverty affect hazard risk?
Poverty may force people to live in areas at risk
Eg shortage of housing can lead to building on unstable slopes prone to flooding and landslides
How does farming affect hazard risk?
Living near a river is good for farming but means people are at risk from floods
How does climate change affect hazard risk?
Climate change may cause more intense storms and hurricanes
Some areas may become wetter and flood more, others may be drier and have droughts / famines
What are tectonic plate margins?
Where tectonic plates meet
On average, how far do tectonic plates move every year?
2cm
The majority of ___ and ___ are found along plate margins
Earthquakes
Volcanoes
Some volcanoes are not near plate margins - these are called…
Hotspot volcanoes
Eg Hawaii
What are the three types of plate boundary called?
Constructive
Destructive
Conservative
What is a constructive plate margin like
Plates are moving away from each other
Magma rises to surface forming shield volcanoes - low viscosity magma
Magma breaking through crust can cause small earthquakes
What is a destructive plate margin like
Plates moving towards each other
Denser oceanic plate subducts beneath continental plate
Friction —> strong earthquakes
Composite volcanoes - high viscosity magna, violent eruptions
What is a conservative plate margin like
Plates moving side by side - opposite or same direction
Only earthquakes formed here - can be very destructive as they’re near surface
No active volcanoes
What is the Pacific Ring of Fire?
Path around Pacific Ocean w many volcanic eruptions + earthquakes
How long is the Pacific Ring of Fire?
24,900 miles long
The Pacific Ring of Fire is also called…
The Circum-Pacific belt
Earthquakes and volcanoes on the Ring of Fire can affect countries such as…
South and North America
Japan
New Zealand
What % of volcanoes are located along the Ring of Fire?
75%
What % of earthquakes occur along Ring of Fire?
90%
Volcanic eruptions + earthquakes in Ring of Fire are caused by ___ plate margins
Destructive
When did the L’Aquila earthquake occur?
2009
When did the Gorkha earthquake occur?
2015
The L’Aquila earthquake measured ___ on the ___ scale
6.3
Richter
The earthquake’s ___ was ___ northwest of L’Aquila
Epicentre
7km
The Gorkha, Nepal earthquake measured ___ on the Richter scale
7.8
The epicentre of the Gorkha earthquake was…
In Barpak, 80km NW of the capital Kathmandu
What were 5 primary effects of the L’Aquila earthquake?
Any 5:
308 killed
1500 injured
67,500 made homeless
10-15,000 buildings collapsed
Estimated cost = US $11,400 million
What were 5 primary effects of the Gorkha earthquake?
Any 5:
8841 killed
16,800 injured
1 million made homeless
Historic buildings destroyed eg Dharahara Tower
Destruction of 26 hospitals and 50% of schools
Estimated cost = US $6.7 billion
What were the secondary effects of the L’Aquila earthquake?
Aftershocks which triggered landslides + rockfalls
House prices + rent increased
Reduced business, tourism and income
What were the secondary effects of the Gorkha earthquake?
Avalanche on Mt Everest
Tourism, employment + income suffered
Food shortages and income loss due to destruction of rice storage
Name 4 immediate responses to the L’Aquila earthquake
Any 4:
Hotels provided shelter for 10,000
40,000 tents given out
Italian Red Cross searched for survivors
British Red Cross raised £171,000
EU granted $553 million
Mortgages and bills suspended
Name 4 immediate responses to the Gorkha earthquake
Any 4:
Nepal requested international help
UK’s DEC raised $126 million
Temporary shelters set up
Tents for 225,000 people
Medical supplies delivered
Sherpas used to hike relief supplies to people - 315,000 were cut off by road
Name 4 long term responses to the L’Aquila earthquake
Any 4:
No taxes in 2010
Students given free public transport and exempt from uni fees for 3 years
Homes took several years to rebuild
Historic buildings expected to take 15 yrs
Scientists + govt official tried for manslaughter
Name 4 long term responses to the Gorkha earthquake
Any 4:
Rebuilding of houses, schools, roads, monuments
$274 million of aid committed to recovery efforts
Mt Everest reopened August 2015
Individuals trained to maintain irrigation channels
Why do people live with the risk from tectonic hazards?
Hazards are rare
Some don’t have a choice eg poverty
Fertile soil
Rocks for building
Mineral deposits
What is monitoring?
Using scientific equipment to detect warning signs of events such as a volcanic eruption or earthquake
How can we monitor volcanoes?
Warning signs before eruptions
Remote sensing - satellites detect heat
Ground deformation
Geophysical measurements
How can we monitor earthquakes?
Generally occur without warning
Some evidence of changes in water pressure, ground deformation + minor tremors
Scientists yet to discover reliable ways to monitor / predict them
How can we predict volcanic eruptions
Based on scientific monitoring
Eg in 2010 an increase in earthquake activity enabled scientists to predict eruptions
How can we predict earthquakes
Impossible to make accurate predictions
Historical records can show areas of greatest risk
How can we protect against volcanoes
Little can be done to protect people + property
Earth embankments or explosives can be used to divert lava flow
How can we protect against earthquakes
Buildings and bridges constructed to resist earthquakes eg shock absorbers
Regular drills
Tsunami walls on the coast
How can we plan for volcanic eruptions
Hazard maps for most dangerous volcanoes
Maps can be used in restricting certain land uses or identifying areas which need to be evacuated
How can we plan for earthquakes
Maps produced to show effects or identify areas most at risk
High value land uses eg hospitals / reservoirs can be protected using the maps
Evacuation drills
What kind of pressure is found at the equator
Low pressure - air is rising
What are trade winds
Surface winds blowing in a consistent direction
What is a tropical storm
Huge storm that develops in the Tropics
Where are tropical storms called hurricanes
USA and Caribbean
Where are tropical storms called cyclones
SE Asia and Australia
Where are tropical storms called typhoons
Japan and Philippines
What is the eye of a tropical storm
The centre of the storm and the calmest part
What is the eye wall
Most destructive part of storm (highest winds), has intense rain and wind
What are conditions like in cloud banks
Strong winds and heavy rain
What scale measures hurricanes
Saffir-Simpson scale
How is a tropical storm formed?
- Air rises - draws up water vapour
- Evaporated air cools and condenses to form clouds
- As air condenses releases heat which powers storm / draws up more water
- Several storms join together
- Storm develops eye / eye wall
- Carried by prevailing winds - gathers strength
- Loses energy over land (friction)
How fast does a storm have to go to be classified as a tropical storm?
75mph
What is the global atmospheric circulation like at the equator
Low pressure
Air is rising
Humid with high temps and high rainfall
What is global atmospheric circulation like 30 degrees away from the equator?
High pressure
Air is sinking
Arid, high temps and low rainfall
What is global atmospheric circulation like 60 degrees from the equator?
Weaker version of equator
Low pressure
Rainfall
Temperate
Where is the Hadley cell?
Equator —> 30 degrees N / S
Where is the Ferrell cell?
30 —> 60 degrees N / S
How will climate change influence the distribution of tropical storms?
As patterns of sea surface temperatures change they may affect distribution
In future tropical storms may affect areas outside current hazard zone
How will climate change influence frequency of tropical storms?
Becoming more frequent - 6 of the 10 most active hurricane years since 1950 have been since the mid-1990s
Some computer models indicate that frequency may decrease but intensity might increase
How will climate change influence intensity of tropical storms?
Hurricane intensity in N Atlantic has risen in last 20 years
Appears to be linked to increasing sea surface temps
More data will be needed to accurately predict
What is the named example of a tropical storm?
Typhoon Haiyan
How did Typhoon Haiyan form?
Water vapour drawn up - condensed to form clouds
Several storms joined together and it developed an eye
Storm carried across Pacific by prevailing winds and reached Philippines
How did people prepare for Typhoon Haiyan?
Moved 800,000 people to evacuation centres
Didn’t anticipate what was coming
Some ignored evacuation warnings
Name 3 primary effects of Typhoon Haiyan
3 from:
6300 died - most drowned by storm surge
30,000 fishing boats destroyed
Buildings damaged by strong winds
Airport badly damaged
Hundreds of thousands displaced
90% of Tacloban city destroyed
Widespread flooding
Name 3 secondary effects of Typhoon Haiyan
3 from:
Flooding caused landslides - remote communities cut off from aid
Ferries and flights disrupted
Looting / violence in Tacloban
Power supplies cut off for a month
Food, water and shelter shortages - disease
14 million affected
Loss of jobs
Damage to hospitals, schools and shops
Fishing industry damaged - livelihoods
What category was Typhoon Haiyan?
5
How fast was Typhoon Haiyan?
Wind speeds of 150mph
What was the average storm surge for Typhoon Haiyan?
7.5
Name 3 immediate responses to Typhoon Haiyan
3 from:
Philippines Red Cross delivered food aid
Governments and aid agencies responded with food, water and shelter
1200 evacuation centres set up
Aircraft carrier and helicopters helped with search + rescue and aid delivery
Name 3 long term responses to Typhoon Haiyan
3 from:
Aid agencies eg Oxfam helped replace fishing boats (source of income)
Rebuilding of roads, bridges, airports
Rice farming and fishing re-established
Homes built away from areas at risk
US, EU and Australia supported new livelihood opportunities
Money / supplied / medical support donated by UN
How can monitoring and predicting help reduce the effects of tropical storms
Satellite and radar technology
Hurricane warnings to tell people when a hurricane is expected
How can protection help reduce the effects of tropical storms
Windows, doors and roofs reinforced
Storm drains in urban areas - prevent flooding
Storm shelters built
How can planning help reduce the effects of tropical storms
Raise individual and community awareness
How has Bangladesh reduced the potential effects of tropical storms
Early warning systems
Cyclone shelters
Greater awareness
Weather is driven to the UK by
South-westerly prevailing wind
What kinds of extreme weather does the UK get
Thunderstorms
Prolonged rainfall
Drought / extreme heat
Heavy snow / extreme cold
Strong winds
How do thunderstorms affect UK
Follow hot weather bringing lightning and torrential rain
Linked with flash flooding eg Boscastle 2004
How does prolonged rainfall affect UK
Leads to river floods, eg winter of 2013/14 which caused flooding across southern England
How does drought and extreme heat affect UK
Causes rivers to dry up and reservoirs to run dangerously low
Heatwave in 2003 killed 20,000 people
How does heavy snow and extreme cold affect UK
Less common but can cause hardship in north of UK
How do strong winds affect UK
Disrupt power supplies
Cause trees to fall which causes damage
Coastal damage from large waves
Where are the Somerset Levels
North and centre of Somerset (W England)
What are the Somerset Levels
An area of coastal plain and wetland in central Somerset
Mainly agricultural land, important habitat for birds and plants
What caused the Somerset Levels floods in 2014
A sequence of south-westerly depressions brought record rainfall in Jan and Feb
High tides and storm surges prevented normal river flow
Rivers had not been dredged for 20 yrs
What were social impacts of the Somerset Levels floods
Over 600 houses flooded
Villages cut off - disrupted work, schools and shopping
Residents evacuated
What were economic impacts of the Somerset Levels floods
Estimated £10 million damage
Farming couldn’t go ahead
Power supply, roads and railway cut off
What were environmental impacts of the Somerset Levels floods
Sewage contaminated floodwater
Debris had to be cleared
Immediate responses to Somerset Levels floods
Media interest generated
Cut off villages used boats for transport
Volunteers helped support
Long term responses to Somerset Levels floods
£20 million flood action plan launched
8km of rivers dredged
Flood defences built, river banks raised
Define global warming
The long term heating of the earth’s surface due to human activities
Define climate change
Long term change in the average weather patterns that have come to define the earth’s local, regional and global climates
What is the Quaternary period
2.6 million years ago to the present day
Global drop in temp, ice age began
How to discuss graphs
GCSE
General pattern / trend
Compare
Specific examples
Exceptions / anomalies
Global effects of climate change
Melting of glaciers - impacts wildlife
Islands under threat
Flooding of agriculture
Four types of evidence for climate change
Rising sea level
Glacial retreat
Seasonal changes
Ice cores
How do we know about temps from a long time ago
Fossil records
Fresh falls of snow trap and preserve evidence of temp
Scientists study oxygen in ocean sediment or water molecules
Ice cores used to reconstruct temp patterns
How does rising sea level provide evidence for climate change
Average level risen 10-20cm in 100yrs
Warming water expands in volume - thermal expansion
Temps rise causing ice to melt and make sea levels rise
How do ice cores provide evidence for climate change
Temp and CO2 are linked
Enclosed bubbles of air - sample of atmosphere
Concentration of CO2 now 40% higher than before industrial revolution
What are ice cores
Cylinders of ice drilled out of an ice sheet / glacier
How does glacial retreat provide evidence for climate change
Snow + ice undergoing global decline
Glaciers are shrinking - some may disappear by 2035
Arctic sea ice thinned 65% since 1975
How do seasonal changes provide evidence for climate change
In 1990s many bird species nested average of 9 days earlier than 1970s
Timing of natural seasons may be advancing eg tree flowering, bird migration
Natural greenhouse effect
Greenhouse gases occur naturally and are part of the atmosphere
Trap heat to keep planet at 15 degrees
Enhanced greenhouse effect
Human activities have increased the concentrations of greenhouse gases
This means more heat is trapped and atmosphere warms up
What are the natural causes of climate change
Orbital changes
Volcanic activity
Solar output
What are the Milankovitch cycles
Three cycles increase or decrease the distance from the sun
What is eccentricity
Over time the orbit changes from circular to elliptical
When the orbit is elliptical less sunlight reaches earth at some points
What is axial tilt
Angle of tilt changes every 41,000 years
Causes more or less sunlight to reach the poles
What is precession
Earth wobbles on its axis
Amount of sunlight varies
How does solar activity lead to climate change
Number of sunspots increases and decreases
When at maximum sun gives off more heat
How does volcanic activity lead to climate change
Volcanic ash can block sunlight
Droplets of sulphuric acid reflect solar radiation back into space
How does CO2 contribute to human causes of climate change
Accounts for 60% of enhanced effect
Global concentration has increased by 30% since 1850
Burning fossil fuels, deforestation, burning of wood
