Hazardos Earth Flashcards
What is the crust made of?
Rock
How thick is the crust?
Varies between 5-70 km thick
How thick is the mantle?
2900 km
What are the two parts of the upper mantle?
Lithosphere and asthenosphere
Where is the lithosphere?
Part of the mantle closest to the crust
What is the lithosphere made out of?
Liquid (molten rock)
Where is the asthenosphere?
Part of the mantle, underneath the lithosphere
What is the asthenosphere made out of?
More rock than molten rock (liquid)
What is beneath the upper mantle?
The lower mantle
What is beneath the lower mantle?
The outer core
How thick is the outer core?
2266km
How hot is the outer core?
4000-5700 degrees centigrade
What is the outer core made out of?
Molten iron and nickel
How thick is the inner core?
1200km
What is the inner core made out of?
Mostly solid iron and nickel
How hot is the inner core?
The same temperature as the surface of the sun
What is the order of the layers inside the earth?
- crust
- lithosphere
- asthenosphere
- lower mantle
- outer core
- inner core
How thick is oceanic crust?
Very thin (1-3 miles)
What is oceanic crust made out of?
Basalt p. The same kind of rock found in the mantle.
Where is the oceanic crust?
The ocean floor
Has the oceanic crust got a hazard got a high or low density?
High density
What is continental crust made out of?
Thick granite
How thick is continental crust?
10-50 miles
Where does continental crust form?
On land
Is it deeper than oceanic crust?
Yes it is the deepest and thickest
What is radioactive decay?
Some elements are naturally unstable and radioactive (e.g uranium), atoms of these elements release particles from the nuclei and give off heat. This is called radioactive decay
What are convection currents?
The movement of the earths crystal plates is due to convection currents which occur in the mantle. These convection currents are created by heat from within the earth.
What is the divergent plate movement?
The tectonic plates move apart.
What is the convergent plate movement?
One plate moves under the other
What is the conservative plate movement?
The plates slide past each other.
What is the collision plate movement?
The plates move towards each other.
Who’s theory proved continental drift and Pangea?
Wegner’s
What was the super continent called?
Pangea
When was Pangea a continent?
250 million years ago
What were the 2 continents called?
Laurasia and Gonclwanaland
When were the the continents Laurasia and Gondwanaland
200 million years ago
What are divergent plates?
When two plates move apart.
What are convergent plates?
One plate moves under the other
What is conservative plates?
Plates slide past each other
What are collision plates?
Plates that move towards each other.
What type of crust do you find divergent plates on?
Oceanic
What tectonic activity do divergent plates cause?
Gentle earthquakes, volcanoes are less violent, but can be more constant.
What type of crust do you find convergent plates on?
Oceanic and continental
What landforms do convergent plates form?
Mountains, ocean trenches e.g Andes
What tectonic activity do converge plates cause?
Big earthquakes
What types of crust can you find collision plates on?
Continental.
What landforms do collision plates cause?
Fold mountains e.g Himalayas
What tectonic activity does collision plates cause?
Big earthquakes
What types of crust do you find conservative plates on?
Continental
What tectonic activity do conservative plates cause?
Massive earthquakes
What is a hot spot?
A place in the centre of a plate where magma rises. This causes the lithosphere to melt and magma pushes through the crust to form volcanoes.
What are the types of volcano?
Hotspot, shield and composite cone.
What shape is a composite cone volcano?
Mountain like, steep slopes, wide base.
What is the lava like that comes from a composite volcano?
- viscous (sticky)
- thick
- ash (pyroclastic flow)
- rockbombs
What is the frequency and magnitude of eruptions for composite volcanoes?
- powerful eruptions
- not very often
- magnitude 4-7
What plate boundaries are composite volcanoes found on?
Convergent
What shape is a shield volcano?
Flatfish, wider, gentle, broad
What is the lava like from a shield volcano?
- slow less violent, runny lava
- doesn’t erupt ash or rock bombs
What is the frequency and magnitude of eruptions from shield volcanoes?
- constantly erupting
- magnitude 2-3
What plate boundaries are shield volcanoes found on?
Divergent
What are seismic waves?
The earthquakes energy being released.
What is the epicentre?
The point on the earths surface above the focus.
What is the focus?
The point inside the crust where the pressure is released
What is a seismometer?
It measure and records seismic waves.
How do earthquakes happen?
- movements of the earths tectonic plates
- concentrated along fault lines (fractures in the earths crust)
- friction builds up along the plate boundaries as they move against each other until finally the energy is released
- this energy is sent out is seismic waves
What is the Richter scale?
The strength or magnitude of an earthquake measured using the Richter scale. The Richter scale is numbered 0-10. It is a logarithmic scale, e.g 6.0 earthquakes is ten wines more powerful than a 5.0.
What causes a tsunami?
- Destructive/convergent plate movement causes earthquake
- sea above earthquake forced upwards
- Sea movement causes a tsunami
- seismic waves spread quickly outwards
- Waves crash onto shite devastating low lying area
What are dark surfaces?
absorb sunlight which is converted to heat. It heats up quickly in summer. (E.g tarmac or soil)
Where does the Gulf Stream begin?
Gulf of Mexico
How long is the Gulf Stream?
10,000 km long
How much colder would our climate be without the Gulf Stream?
5-10 degrees colder
Why might the Gulf Stream stop?
Global warming
What is the global circulation model?
Is a theory that explains how the atmosphere operates in a series of 3 cells each side of the equator.
Light rays hit the equator and spread out. And the greenhouse gas effect traps the light from the sun.
Hadley cell:
- largest cell
- warm air rises from the equator and travels around 30 degrees north/south before returning
Polar cell:
- smaller than Hadley cell
- thermally direct
- cold air sinks at the North Pole, before flowing south at the surface
Ferrel cell:
- is found between Hadley and polar cell
- lies between 60 degrees north and 30 degrees north
- powered by Hadley and polar cells
- the smallest cell
Low pressure is
- warm air rises in areas of low pressure. As it rises and cools, water vapour condenses to for, clouds precipitation.
- the weather in areas of low pressure is often cloudy
High pressure:
- as air is heated at the equator , it rises and begins to descend at around 30 degrees latitude
- as the air descends it warms
- the now warm air stops condensation stops cloud formation as condensation is less likely to happen
What is a pressure belt?
A pressure belt is an area of low pressure between 0 and 30 degrees , here there is year round rainfall
What is the ITCZ?
It’s a convergence zone at the thermal equator where trade winds meet. It’s a low pressure belt that migrates with the changing position of the thermal equator.
Theories for causes of past climate change:
- sunspot theory
- orbital theory
- the eruption theory
- asteroid collisions
What is the sunspot theory?
Sunspots tell us that the sun is mire active than usual. The more spots the more solar energy being fired out from the sun toward the earth.
What is the eruption theory?
The eruption produced ash as sulphur dioxide
- ash into the atmosphere which blocks the sun rays
- causes global cooling.
Asteroid collision theory?
Asteroid hits earth, dust and ash block the sun and earth cools.
What is orbital theory?
The earths orbit around the sun changes shape, the earth is sometimes more tilted on its axis than normal, earths axis wobbles
How can tree rings help with last climates?
Periods of growth can be seem from the number of rings in a tree, larger the gap between the rings the better the climate was.
What can we use to reconstruct past climates?
- historical sources
- ice core
- tree rings
What is the enhanced greenhouse gas effect ?
Is the impact on the climate from additional heat being retained due to increased amounts of carbon dioxide and greenhouse gases that humans have released into the world.
Future predictions for the world?
- 18-59cm sea level rise
- small islands lost to sea
- increased drought
- climates will rise
- stronger and more frequent storms
What do you need for tropical cyclones to develop?
Sea must be 26.5 degrees or higher ,when the wind is shear (the difference in windspeed) between higher and lower parts of the atmosphere is low.
Where is the source area of most tropical cyclones?
Between 5 degrees and 30 degrees north and south of the equator- any further the water isn’t warm enough
When do tropical cyclones happen the most in the northern hemisphere?
June to November
When do tropical cyclones happen the most in the Southern Hemisphere?
November to April
What creates strong winds in cyclones?
Warm , moist air rises and condensation occurs. This releases huge amounts of energy, which makes the storms powerful. The rising air creates an area of low pressure, which increases surface winds
What causes cyclones to spin?
The earths rotation deflects paths of the winds causing the cyclone to spin
Why do tropical cyclones move towards the west?
Because of easterly winds near the equator
Why might cyclones curve as they move away from the equator?
There path might start to curve east as they get caught in mid-latitude westerlies.
Why do cyclones get stronger?
Energy from warm water
Why do cyclones dissipate (loose strength)?
They move over to cooler water because the energy supply from warm water is cut off
What is used to predict a cyclone?
Computer models
How can a cyclones magnitude explode measured?
By measuring its wind speeds
What types of defences can you use against cyclones?
Sea walls, buildings built to withstand a storm surge
When did hurricane Katrina happen?
29th august 2005
When did they issue a hurricane warning for Katrina?
On 26th august for Louisiana, Mississippi and Alabama
How many people were killed during hurricane Katrina?
1800
How many houses were destroyed during hurricane Katrina?
300000 houses
