Natural Hazards Flashcards
What are the 4 different plate margins called
Destructive, constructive, conservative, collision
When does a constructive plate boundary occur
When two plates move away from each other
Convection currents moving in opposite directions in the mantle move the two plates apart
Magma will rise up and form a shield volcano
Erupts and then cools as new land, this can create huge ridges of undersea mountains
Two oceanic plates
When and what makes a destructive plate boundary occur
Usually involve an oceanic and a continental plate
Plates move towards one another
Process that occurs at a destructive plate margin
-Plates collide
-oceanic plate is forced under the continental plate because of subduction
-the plate sinks into the mantle to form magma
-pressure of magma builds up and escapes through weaknesses in the rock and rises and through a composite volcano
-eruptions are violent with lots of steam and ash
Why does subduction occur in a destructive plate margin
Because the oceanic plate is denser than the continental plate
What happens at a conservative plate margin
Plates move past each other and different speeds
As the plates move friction occurs and plates become stuck
Pressure builds as plates try to move when pressure is released it sends our huge amounts of energy causing an earthquake
Why can conservative plate margins be so destructive
They occur close to the earths surface
What happens at a collision plate margin
Two continental plates collide
Neither can sink and so the land buckets upwards to form fold mountains
Earthquakes can also occur
What are the two types of crusts
Oceanic and continental
What is oceanic crust
found underneath the oceans. It is denser than continental crust and can be subducted.
What is continental crust
found under land masses or continents. It is generally older than oceanic crust and is less often destroyed.
Where are earthquakes found along
All types of plate margins
Where are volcanoes formed along
Only occur at constructive and destructive plate margin
Factors affecting the risk of natural hazards
Urbanisation
Poverty
Location
High population density
Examples of atmospheric hazards
-storms
-tornadoes
-droughts
Definition of natural hazard
A natural event or phenomenon that poses a threat to human life or has a social impact
Example of hydrological hazards
-floods
-tsunamis
-storm surges
Example of geological hazards
-earthquakes
-volcanic eruption
-avalanches
What was alfred wegners theory
About continental drift that there was once a huge super continent
What was the evidence for Alfred wegners theory
-all continents fit together
-plant and animals were all across the world
-same geological structures across continents
What is a rift valley
Forms when earths tectonic plates move apart so river or sea forms
Name the 4 layers of the earth
Crust, mantle, outer core, inner core
What is the temperature of the core
Around 5500 degrees
Characteristics of continental crust
Granite rock type
Light
Old
Less dense
Found on land
Characteristics of oceanic crust
Basalt rock type
Found under seas
Young
Dense
What is year was the chile earthquake
2010
What year was the Nepal earthquake
2015
What was the magnitude of the chile earthquake compared to the Nepal earthquake
Chile = 8.8
Nepal = 7.9
What was the cost of the chile earthquake compared to the Nepal earthquake
Nepal = 5 billion dollars
Chile= 30 billion dollars
How many people were killed in Nepal compared to the chile earthquake
Nepal = 9000
Chile = 500
What other natural hazard did the Nepal earthquake trigger
Landslides and avalanches blocking roads
What other natural hazard did chile earthquake trigger
Tsunami
Level of income of Nepal vs chile (GNI)
Chile = 14,100 dollars
Nepal = 970 dollars
Features of a composite volcano
Tall coned
Thick lava
Narrow base
Less frequent
More explosive
Features of a shield volcano
runny lava
Dome
Less explosive
Wide base
Chile immediate and long term responses :
Immediate = raised 60 million dollars which was enough to build 30,000 small emergency shelters
Long term = a month after a housing reconstruction was put in place by the government to help nearly 200,000 households
Immediate and long term responses of Nepal earthquake:
Immediate = half a million tents provided to shelter for homeless, search and rescue teams lifted rubble, used camera
Long term = roads were repaired and landslides cleared, held an international conference to discuss reconstruction and seek financial and technical support with other countries
Impact of eyjafjallajokul volcanic eruption
Havoc on European flight path (100,000) flights cancelled
Homes and roads damaged
What is a tilt meter
A sensitive instrument that can detect changes to the tilt of earth
We are able to see every change in the plates and detect if their are any seismic waves
Also monitors levels of gas around a volcano
Why live near a volcano
Mining, heating, tourism, farming and soils
Ways to predict natural hazards
Seismometer = pick up vibrations at earths crust
Heatseeking cameras = to see volcanic heat
Tilt meters = measure earths movement
Find water which is 27 degrees as this could cause tropical storm
Ways to protect against natural hazards
Shock absorbers for earthquakes
Roads and buildings can be built to withstand power of earthquakes
Ways to plan for a natural hazard
Earthquake drills are held in schools
Put together emergency kits and store them at home or work
Evidence for climate change
Rising sea levels
Temperature
Glacial retreat / melting ice
Historical evidence from ice cores (to show greenhouse gases concentrations have changed in the past)
How much has sea levels risen
Between 10 and 20 cm
What is the quaternary period
Geological period that covers the last 2.6 billion years
How is glacial retreat evidence for climate change
-photographic evidence shows that the worlds glaciers have been melting causing them to retreat
How is ice cores evidence for climate change
-ice cores detects changes in temperatures
-these ice cores go as far back as 400,000 years ago
-and concentration of greenhouses gases can be seen
What is the enhanced greenhouse effect
-we are producing more greenhouse gases
-so more heat reflected into atmosphere
-and less heat will escape into space so it’s trapped
-this will result in earth heating up quicker
What percentage of animals are at risk of extinction due to climate change
8 percent
How much ice has Antarctica lost compared to 25 years ago
3 times as much
Impacts of climate change
-Lower level of rainfall and high temperature
-Longer food growing seasons
-countries could become underwater due to river and sea levels
Positives to using fossil fuels
Generate large amounts of energy quite cheaply
Locating where fossil fuels are is easy
Means for extracting fossil fuels already exist
Negatives of fossil fuels
Suppliers are running out and new courses are harder to get to
Release carbon dioxide contributes to global warming and greenhouse effect
Oil spills can cause environmental damage
What is afforestation
Growing and planting of tress
Challenges to afforestation
Takes 20-40 years to actually absorb a significant amount of carbon
Expensive
Some climate can’t have trees
What is carbon capture
Carbon is collected and is injected deep into the ground after it is compressed turning it into a liquid, its injected into porous rock that carbon fills and has an impermeable layer that acts as a cap to prevent it from moving
Advantages of carbon capture
Allows up to 90% of carbon dioxide to be caught
Reduces the carbon emissions of fossil fuel power plants
Disadvantages of carbon capture
Concerns around safety due to possibility of leakages and environmental contamination
Large amounts of excess energy required to produce the equipment needed
Earthquakes might result in co2 leakages
Ways to protect homes from natural hazards
Raised on stilts
Paint white so heat is reflected
Green roofs to reduce heat
Aerodynamic
Natural causes of climate change
-volcanic eruptions
-sunspot theory
-eccentricity orbital theory
-axial tilt orbital theory
How does volcanic eruptions cause climate change
Can emit lots of ash sulfur dioxide which prevents solar energy reaching earth which lowers the temperature
How does the sunspot theory cause climate change
They are dark spots on the earth that give off more solar energy (heat)
How does eccentricity orbital theory cause climate change
Earths orbit turns from a circle to an oval every 100,00 years so that means earth is further from sun so less heat from sun
How does axial tilt orbital theory cause climate change
Earths tilt changes every 4000 years this means that earths seasons could be shortened or extended
Human causes of climate change
Burning fossil fuels
Agriculture
Deforestation
How is high pressure formed
-air that is sinking towards the ground surface forms areas of high pressure
How is low pressure formed
Air that is rising from the ground surface forms low pressure. Winds on the ground move towards these areas of low pressure
Name the types of cells in global atmospheric circulation
Polar cell = at the north and South Pole
Ferrel cell = between polar and Hadley cell
Hadley cell = between equator and Tropic of Cancer / Capricorn
How does atmospheric circulation system explain the UKs mild cloudy and wet weather
-uk is located just below 60 degeees line of latitude
-Uk is close to boundary of cold polar air moving down from north and warm sub tropical airs moving up from the south
-there is rising air and low pressure belts
-rising air cools and condenses forming cloud and rain
How does global circulation affect the worlds weather
-the circulation cells, pressure belts and surface winds affect the weather around the world
-for exemplary the trade winds in the tropics are responsible for driving tropical storms
Characteristics of warm air
-it’s less dense
-rising air
-low air pressure
-air cools and form clouds
-warm air rises and holds lots of moisture
Characteristics of cold aid
-more dense
-sinking air
-high air pressure
-clear sunny skies no clouds
-little moisture in air
Why is there high rainfall at the equator
High solar energy radiating and heating the ground
Air gets heated so then rises
Air cools down condenses and forms clouds then it rains
Key conditions needed to form tropical storms
Warm oceans (over 27 degrees)
Low pressure
Light cross winds to begin with
How do tropical storms form
-Ocean water evaporates, the warm moist air rises creating an area of low pressure
-air cools and condenses and forms clouds
-air begins to spin because of the rotation of the earth
-spinning storm is carried across the ocean as it moves across warmer ocean it becomes stronger
What is the Coriolis effect
The Coriolis effect makes storms swirl clockwise in the Southern hemisphere and counterclockwise in the Northern Hemisphere.
Primary effect of beast from the east snow storm
50cm of snow fell
Secondary effect of beast from the east
Snow melt and high tides caused flooding
Responses to the beast from the east
Royal air force was drafted in to help relief efforts in snow
Weather events that could effect the UK
Flooding (heavy rainfall)
Extreme cold (low pressure)
Drought (high temp)
Storms (strong winds)
Primary effects of typhoon haiyan
-29,000 people died
-cost damage of 12 billion dollars
-roads were blocked
-homes destroyed
Secondary effects of typhoon haiyan
-education disrupted as schools destroyed
-airport badly damaged
-flooding caused landslides
Immediate responses to typhoon Haiyan
- over one million food packs distributed
-televised warning
Long term responses to typhoon haiyan
-upgraded damaged buildings with build back better campaign
-Oxfam replaced fishing boats
How are tropical storms measured
Saffir Sampson scale
How does the Saffir Sampson scale measure tropical storms
Rating 1-5 based on wind speed, category 5 being the most dangerous with wind speeds of over 157
What was the wind speeds of typhoon haiyan
305 km/h
How can you monitor for tropical storms
Check for areas of low pressure and sea temperatures of 27 degrees
What is slab pull
as the crust subducts into the mantle gravity will pull the plate further into the mantle. The weight of the plate behind it will also push it down further
What is ridge push
The warm magma rises from the core and will PUSH the plates at the top upward (ridge push) as the plates stop the material rising further. This means the magmal then moves out sideways taking the crust along with it. The magma begins to cool at the surface of the mantle before sinking back down to the bottom to be heated again.
How do convection currents work
When magna nearest to the core of the earth is warmer and so less dense. This will result in it rising. The magma nearest to the crust is cooler and more dense and will sink. This repetitive cycle is convection currents
What is atmospheric circulation
Air from the equator rises and moves towards the poles, then cools down and sinks at approximately 30 degrees north and south of the equator. The sinking air creates an area of high pressure with very little rainfall. Some of the air moves back to the equator as surface winds called trade winds
Effects of boscastle flooding
80 homes destroyed
Coastal pollution
Response management to boscastle flooding
Deepened and widened river, created natural wetland, rebuilt bridges and homes
Describe the link between air pressure and surface winds
Winds blow from high to low pressure. The trade winds blow from 30 degrees N and S towards the equator
