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Geography > Unit 1 - Hazardous Earth > Flashcards

Unit 1 - Hazardous Earth Flashcards

1
Q

What is the ITCZ?

A

The intertropical convergence zone is an area of low pressure near the equator which brings rain

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2
Q

How does the ITCZ form?

A

When two masses of air meet and converge

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3
Q

When hot air rises, it creates ___ pressure

A

low

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4
Q

When dense cold air sinks, it creates ___ pressure

A

high

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5
Q

Does high or low pressure cause heavy rainfall?

A

Low

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6
Q

What were the 4 causes of climate change in the past?

A

Volcanic activity, Asteroid collisions, Variations in solar output, the orbital theory

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7
Q

How did volcanic activity impact the climate?

A
  • Large explosive volcanoes erupted and released ash and sulphur dioxide gas
  • The ash and gas were spread around in the stratosphere by high-level winds
  • The blanket of ash and gas stop sunlight from reaching the Earth’s surface and sunlight instead reflects back to space
  • This cools the planet and lowers the average temperature
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8
Q

How did asteroid collisions impact the climate?

A
  • 1km sized asteroids strike the Earth around once every 500,000 years
  • An asteroid this big would blast millions of tonnes of ash and dust into the atmosphere
  • This would cool the climate as dust and ash would block incoming sunlight
  • Effects could last between 5-10 years
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9
Q

How did variations in solar output impact the climate?

A
  • Sunspots are black areas on the sun’s surface
  • Sometimes, the sun has many sunspots and sometimes, the sunspots disappear
  • Lots of sunspots means that the sun is more active than usual and that more solar energy is being fired towards the Earth
  • More solar energy means there will be an increase in the Earth’s temperature
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10
Q

What is the orbital theory and how does it affect climate?

A
  • Changes in the way Earth orbits the sun
  • These changes alter the amount of sunlight the Earth recieves and where sunlight falls on the Earth’s surface
  • These changes are called Milankovitch Cycles
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11
Q

What are the 3 orbital changes the Earth undergoes?

A
  1. It takes 100,000 years for the Earth’s orbit to change from being more circular to an ellipse and back again.
  2. Over a cycle of 41,000 years, there is continous change in the Earth’s rotational axis
  3. Over a cycle of 26,000 years, a gradual shift occurs in the orientation of the Earth’s axis of rotation, producing a ‘wobble’
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12
Q

What are the 3 sources of evidence for past climate change?

A

Ice cores, tree rings and historical sources

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13
Q

How do ice cores show evidence of past climate change?

A
  • Ice cores contain layers of ice, oldest at the bottom and youngest at the top
  • Each layer is one year of snowfall
  • There are air bubbles trapped in the ice layers which preserve air from the time the snow fell
  • The air bubbles contain carbon dioxide, so by drilling a core through the ice you can measure the amount of carbon dioxide that was present at the time
  • More carbon dioxide = climate was warmer / interglacial period
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14
Q

How do tree rings show evidence of past climate change?

A
  • Each ring of a tree is one year of its life and in temperate climates, trees grow every summer
  • The years which were warmer and wetter would’ve caused more growth in the tree than if it was colder and drier
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15
Q

How long do trees normally survive and how are they often preserved?

A
  • Trees rarely survive more than a few hundred years
  • Some fossils of trees are preserved in peat bogs and can be thousands of years old.
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16
Q

What are the different types of historical sources?

A
  • Old photos, drawings and painting
  • Written records: diaries, books and newspapers
  • The recorded date of regular events like harvest
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17
Q

What is the disadvantage of using historical sources to evaluate climate in the past?

A

They are unreliable as they weren’t intended to be used to study climate

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18
Q

Warm periods are called ___ and cold periods are called ___

A

interglacials, glacials

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19
Q

What is the Quaternary period?

A

2.6 million years ago to the present

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20
Q

What is the natural greenhouse effect?

A
  • When greenhouse gases like carbon dioxide and methane act like an insulating layer by letting short-wave radiation that the Sun emits into Earth but trapping some of the long-wave radiation that the Earth emits out, causing them to reflect off of the greenhouse gases and come back to Earth which heats it
  • Some of the short wave radiation also gets absorbed and is converted into long wave (heat) radiation
  • This helps keep the planet warm
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21
Q

Which human activities contribute to production of greenhouse gases? (enhanced greenhouse effect)

A

Farming, industry, energy, transport

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22
Q

How does farming contribute to the enhanced greenhouse effect?

A
  • Farming of livestock produces a lot of methane
  • Flooded fields emit methane
  • Trees absorb and store carbon dioxide so when land is cleared for agriculture, it stops the absorption of carbon dioxide which leaves more in the atmosphere
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23
Q

How does Industry contribute to the enhanced greenhouse effect?

A
  • Most industry uses a lot of energy
  • Some industrial processes also release greenhouse gases (cement is made from limestone which contains carbon, so when cement is produced, lots of carbon dioxide is released into the atmosphere)
  • Industrial waste may end up in landfill sites where it decays and releases methane
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24
Q

How does the use of energy contribute to the enhanced greenhouse effect?

A
  • Carbon dioxide is released into the atmosphere when fossil fuels like coal, oil and natural gases are burnt
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25
Q

How does the use of transport contribute to the enhanced greenhouse effect?

A
  • Most transports (like cars, ships, planes etc) run on fossil fuels which release greenhouse gases when burnt
  • Car ownership is rapidly increasing in developing countries –> more cars on the road –> more congestion and more greenhouse gases produced
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26
Q

What are the 4 pieces of evidence that human activity is causing climate change?

A

Declining arctic ice, the rise in global temperatures, sea level rise and warming oceans, extreme weather events

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27
Q

What is eustatic sea level rise?

A
  • Warmer temperatures are causing glaciers to shrink and for ice sheets to melt
  • The melting of ice on land means that water stored on land as ice returns to the oceans which causes sea levels to rise
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28
Q

What is thermal expansion?

A
  • When water in the oceans expands as it gets warmer
  • Scientists think that this accounts for about half of the measured rise in sea levels
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29
Q

What are future predictions of climate change by 2100?

A
  • Temperatures will rise between 1.1 degrees and 6.4 degrees
  • Sea levels will rise by between 30cm and 1 metre
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30
Q

Why is it hard to predict the future of climate change?

A
  • We don’t know how big the population will be
  • We don’t know if people will change their lifestyle (using less energy etc)
  • We don’t know whether fossil fuels will continue or whether it will be replaced by renewables
31
Q

What are the 3 names for tropical storms and why do they have these names?

A
  • Typhoon = western north pacific
  • Cyclone = indian ocean and south pacific ocean
  • Hurricane = north atlantic and pacific coast of USA
32
Q

What hazards do tropical cyclones bring?

A

Strong winds, storm surges, intense rainfall, landslides

33
Q

Explain what hazard storm surges bring

A
  • They cause flooding which is caused by unnaturally high tides
  • They are so high because of the low air pressure which raises sea levels
  • Winds drive waves onshore
  • Coastal flooding occurs
34
Q

What are the 3 conditions needed for tropical storms to form?

A
  • Strong winds in the troposphere because it causes warm air to rise up rapidly
  • Strong coriolis effect (rotation) so normally between 0 and 30 degrees latitude (not near the equator)
  • Large, still, warm ocean with the surface temperatures being greater than 26.5 degrees
35
Q

Why do tropical cyclones require a supply of warm, moist air to form?

A
  • Warm air is light and so rises and expands creating an updraft
  • This causes the air to be of low pressure, with the lowest presure being in the middle of the cyclone (eye of the storm - made of calm, descending, dense air)
  • The bigger the difference in air pressure between the cyclone and the Earth’s surface, the stronger the winds will be
36
Q

How many milibars of air pressure does an average tropical cyclone consist of?

A
  • Air pressure in a cyclone is usually around 950 milibars (compared to the Earth’s surface which is normally around 1013 mb)
37
Q

Describe the stages in how a tropical cyclone is formed

A
  1. Warm air currents rise from the ocean. As the warm air rises, more air rushes in to replace it, then that air also rises, drawn by the draught above.
  2. Updraughts of air contain huge volumes of water vapour from the oceans. They condense to form cumulonimbus clouds. Condensation releases heat energy stored in water vapour, which powers the cyclone further
  3. The coriolis force (caused by the Earth’s rotation) leads to spiralling currents of air around the centre of the cyclone, resembling a whirling cylinder. 4.As it rises, it cools, and some descends to form a clear, cloudless, still eye of the storm.
    As the tropical cyclone tracks away from its source, it’s fed new heat and moisture from the oceans, which enlarges it
  4. Once it reaches a landmass, it loses its energy source from the ocean. Air pressure rises as temperature falls, winds drop and it decays to become a mere storm.
38
Q

What 2 things is heat distributed by?

A

Pressure differences and ocean currents

39
Q

How does the land and the sea heat up differently due to pressure differences?

A

Land
- Heats quickly in summer and cools quickly in winter
- Air is heated above, becomes lighter and rises
- So forms low pressure in summer and high pressure in winter

Ocean
- Takes longer to heat and cool so air is dense and cool in summer
- Forms high pressure in summer and low pressure in winter

40
Q

How do ocean currents distribute heat?

A

Cold, salty water sinks at the Poles. It then flows towards the Equator is warmed again, creating a convection current

41
Q

Facts, Primary and secondary impacts of cyclone Aila

A
  • In May 2009, Cyclone Aila killed 190 people and made 750,000 people homeless which were the primary impacts.
  • Secondary impacts included crops being destroyed, sickness spread from contaminated water and farm animals being killed.
42
Q

Facts and impacts of Hurricane Katrina

A

In 2005, Hurricane Katrina was the worst hurricane to hit the USA.
Its levees / embankments collapsed which flooded 80% of New Orleans.
→ Faulty maintenance and design of the levees were partly to blame.
1,833 people died and it cost the economy $108 billion.
Most of New Orleans are below sea-level which is where many of the poor African-American suburbs are located.
Many of the poor and elderly were left behind
80% of the city was evacuated and some residents sheltered in the Super Dome stadium.

43
Q

What is continental crust made out of and how thick is it?

A
  • Made mostly of granite which is a low density igneous rock
  • 30-50 km thick
44
Q

What is oceanic crust made out of and how thick is it?

A
  • Much thinner, 6-8 km thick
  • Denser and made of basalt which is an igneous rock
45
Q

What are the layers of the Earth?

A

Lithosphere, asthenosphere, lower mantle, outer core, inner core

46
Q

Describe the asthenosphere

A

The asthenosphere is a partly molten partly solid ‘lubricating’ layer made of peridotite under the lithosphere

47
Q

What material is the core composed of and what are the states of the inner core and the outer core?

A
  • The outer core is liquid
  • The inner core is solid because the pressure is so great.
  • They are both composed of iron and nickel.
48
Q

Heat from inside the Earth is called ___

A

Geothermal

49
Q

Describe the Earth’s heat engine

A

There are radioactive elements like uranium and thorium in the Earth’s core and mantle which decays and produces heat which raises the temperature of the core.

50
Q

What are plumes?

A
  • Plumes are concentrated zones of heat and they are the part of convection cells where heat moves towards the surface
  • Plumes bring magma to the surface, and if the magma breaks through the crust, it will erupt as lava in a volcano
51
Q

What are the 2 types of ways in which plumes can rise as and what do they form?

A
  • Long sheets of heat which form divergent plate boundaries
  • Columns of heat which form hot spots
52
Q

What are the 3 types of plate boundaries and how are they formed?

A
  • Divergent = Formed when 2 plates move apart
  • Convergent = Formed when 2 plates collide
  • Conservative = Formed when 2 plates slide past each other
53
Q

How is new oceanic crust constantly being formed in divergent plate boundaries?

A
  • Convection currents bring magma up from the mantle
  • The magma is then injected between the separating plates
  • As the magma cools, it forms new oceanic crust
  • The plates continue to move apart allowing more magma to be injected
54
Q

How is old oceanic crust being destroyed in convergent plate boundaries?

A
  • By subduction (when oceanic crust sinks into the mantle at a convergent plate boundary and melts back into the mantle)
55
Q

What are the types of volcanoes and earthquakes that can be formed at conservative plate boundaries?

A
  • No volcanoes
  • Destructive earthquakes up to magnitude 8.5 and small earth tremors almost daily
56
Q

What are the types of volcanoes and earthquakes that can be formed at divergent plate boundaries?

A
  • Shield volcanoes that aren’t very explosive or dangerous and they form in fissures (cracks in the crust) and erupts basalt lava at 1200 degrees
  • Small earthquakes up to magnitude 5-6
57
Q

What are the types of volcanoes and earthquakes that can be formed at convergent plate boundaries?

A
  • Very explosive, destructive, dangerous composite volcanoes. Steep sided, cone-shaped and erupt andesitic lava at 900-1000 degrees
  • Very destructive earthquakes up to magnitude 9.5 and landslides are triggered
58
Q

What are collision zones?

A
  • They are a type of convergent plate boundary which form mountain ranges like the Himalayas.
  • 2 continental plates of low-density granite collide, pushing up mountains
59
Q

What are the types of volcanoes and earthquakes that can be formed at collision zones?

A
  • Volcanoes are rarely formed
  • Destructive earthquakes up to magnitude 9
  • Landslides are triggered
60
Q

What type of magma do composite volcanoes have and what are the properties of it?

A

Andesitic magma
- Lower in temperature
- Has a higher silica content
- Very viscous (sticky)

61
Q

What type of magma do shield volcanoes have and what are the properties of it?

A

Basaltic magma
- High in temperature
- Very low silica content
- Very runny

62
Q

What plate boundary is Japan on and what plates are they?

A
  • Japan is on a convergent plate boundary where the Pacific Plate (oceanic) is subducted beneath the Eurasian plate, causing active volcanoes.
63
Q

What are some benefits that Sakurajima provides?

A
  • 40% of the land is fertile volcanic soil
  • Hot springs and lava flows are a popular tourist attraction
  • The sheltered bay makes a good port and fishing is an important industry
  • The 1914 lava flow joined the island to the main land
64
Q

What are some risks that Sakurajima provides?

A
  • 7,000 people live at the base of the volcano
  • Kagoshima has a population of 650,000 people and a big eruption could devastate it
  • The volcano hurls volcanic bombs over 3km from its crater
65
Q

What are some ways in which Japan monitors Sakurajima?

A
  • Tiltmeters detect when the volcano swells up as it fills with magma
  • Boreholes measure water temperature as magma heats it up
  • Concrete shelters protect against volcanic bombs and ash
  • A tunnel in the volcano has seismometers which monitor earthquakes as number of earthquakes increase as magma rises
  • Aircrafts used to measure how much gas the volcano gives off
  • Evacuation signs clearly signposted
66
Q

Sakurajima has erupted since the ____ sometimes ____ times a year

A

Sakurajima has erupted since the 1950s sometimes 200 times a year

67
Q

In developed countries tectonic hazards cause more ____ costs but less ___ costs

A

economic costs
social costs

68
Q

Social impacts of Mt Nyiragongo (2002)

A
  • 100 people died
  • 12,500 homes were destroyed
  • 120,000 were left homeless
  • Disruption to the mains water supplies caused concern about the spread of diseases
69
Q

Economic impacts of Mt Nyiragongo (2002)

A
  • Poisonous gases caused acid rain which affected farmland and cattle, so many farmers lost income
  • Due to poverty, most people couldn’t afford to rebuild their homes
70
Q

What was the relief effort that was taken place after the devastation and who was behind it?

A
  • The UN and Oxford began a relief effort
  • The UN sent 260 tonnes of food in the first week and families got 26 kg of ration
  • In the UK, a TV appeal raised money and governments around the world gave $35 million dollars to supply aid
71
Q

When did the Goma Volcano Observatory predict the volcano was next going to erupt and when did it actually erupt? Who did they get their fundings from?

A
  • They predicted that it was going to erupt between 2024 and 2027, but it actually erupted in 2021 and took the lives of 32 people, mostly in traffic accidents as they rushed to evacuate the place
  • They got their fundings from the World Bank
72
Q

How are earthquakes formed?

A

Underground, tectonic plates try to push past each other along fractures, building up pressure which is suddenly released, sending out pulses of energy

73
Q

What is the focus and the epicentre of an earthquake and where does the focus need to be for the earthquake to be more destructive?

A
  • Energy travels outwards from the focus (origin) as earthquake waves
  • The shallower the focus, the more destructive the earthquake
  • The location on the earth’s surface above the focus is the epicentre which experiences the most shaking
74
Q

How are tsunamis formed?

A
  • The seabed jolts upwards which forces the water up
  • In the ocean, the wave height is less than a metre, but as it reaches the coast, it bunches up and slows down. Wavelength drops but wave height increases dramatically up to around 30 metres

Geography (2 decks)

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