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Geography > Tectonics > Flashcards

Tectonics Flashcards

1
Q

What happens when two oceanic plates pull apart?

A
  • Pull apart due to convection current and bulging up of magma which pushes plates apart and forms cracks
  • Constructive plate boundary
  • Runny basalt lava rises up and forms shield volcanoes
  • Mid Atlantic ridge
  • North American Plate and Eurasian Plate
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2
Q

What happens when two continental plates pull apart?

A
  • Rift basin e.g Great Africa Rift Valley

- Magma bulges up and pushes plates apart and causes cracks where gases etc rise and volcanoes form

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3
Q

Give an example of destructive plate margins

A

Where Nazca Plate and South American Plate meet- Peru Chile Trench

Fold mountains eg. Himalayas- two continental- Indo-Australian and Eurasian Plate

Stratovolcano eg. Nevado del Ruiz

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4
Q

Give an example of transform plate boundary?

A

North American(1cm/y) and Pacific Plate(6cm/y)

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5
Q

What are the features of a volcano?

A
  • VENT: main outlet for magma to escape
  • MAGMA CHAMBER: collection of magma under crust
  • CONDUIT PIPE: where magma rises up to surface
  • PARASITIC CONE: mainly in stratovolcanoes, when main chamber is clogged, magma breaks through side
  • SIDE VENT: smaller outlets for magma
  • FLANK- side of volcano
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6
Q

What is a pyroclastic flow?

A

Avalanches of red hot gas and ash and volcanic bombs p to 700kmph

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7
Q

What is a lahar?

A
  • Hot fast moving mudflows down the side of volcanoes.
  • Ice melting created large volumes of water which sweeps down volcano picking up debris and soil and its density/ overall volume increases to form hot mudflows
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8
Q

How do hotspot volcanoes form?

A

When crust moves along over an especially hot part of mantle close to crust- plume which stays in the same place and rises to form volcanoes.

Eg. Kilauea in Pacific Ocean- Hawaii

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9
Q

What is a dormant volcano?

A

One that hasn’t erupted in 10,000 years

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10
Q

What is an active volcano?

A

One that has had an eruption in the past 10000 years

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11
Q

How do you predict volcanoes?

A
  • Satellites use infra red to monitor changes in thermal energy near volcano as magma rises
  • Remote sensing- satellite sensors detect sulphur dioxide emissions(main component of volcanic gases)
  • Seismometer- detect vibrations as magma rises
  • GPS- to see minute changes in position of crust
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12
Q

What are the primary effects of a volcano?

A
  • pyroclastic flows
  • nuées ardentes
  • Homes destroyed- people dead
  • Businesses destroyed under as lava eats through it
  • Destruction of crops and farmland
  • Damage water supplies
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13
Q

What is a nuées ardentes?

A

Turbulent cloud of gas, ash, and rock fragments flowing close to the ground after violent ejection from a volcano.

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14
Q

What is a natural hazard?

A

It is a naturally occurring event that has the potential to affect humans and their property or the environment (in a negative way).

Tectonic hazards and Climatic hazards

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15
Q

What are the primary effects of an earthquake?

A
  • Collapsing bridges/railways etc
  • Collapsing buildings
  • People injured/killed
  • Gas pipes burst
  • Water/electricity supply disrupted
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16
Q

What are the secondary effects of earthquakes?

A
  • Landslides
  • Tsunamis- sea bed jolts up and creates massive waves which slow down but increase height up to 30m
  • Leaking gas leads to fire
  • Leaking water = contaminated water flood= cholera
  • Can’t get aid/supply in if transport is down
  • Job lost as businesses or farmland destroyed= financial loss
17
Q

How to predict earthquakes?

A
  • Look at patterns for past eruptions- computer models: seismic gap theory
  • Look at smaller eruptions happening nearby asses if it will come here
  • Monitor radon gas emissions
  • Cracks form in the ground
18
Q

How to reduce impact of earthquakes?

A
  • Warning systems to warn people to prepare = less panic
  • Building planning to not build where the earthquake is most severe
  • Having evacuation points in towns/ shopping malls etc
  • Emergency service trained to evacuate efficiently
  • Better building codes so they withstand earthquake
  • Earthquake proof roads/ bridges
  • Try to predict earthquake
  • Emergency supply kits
19
Q

Why are earthquakes more severe in LEDCs?

A
  • No building codes to withstand earthquake
  • Less trained people to help evacuate or treat injured- more deaths
  • Not enough technology to predict and or give out warnings- rural areas have no network coverage
  • Roads/ railways built of inferior quality so damage more easily so evacuations or emergency aid not able to be given
20
Q

Why do people continue to live in earthquake prone areas?

A
  • Family links
  • No money to move
  • Good climate
  • Insurance covers losses- can afford to rebuild
  • MEDCs can protect people in earthquakes- strong buildings, good emergency services etc
  • Lots of jobs in that area
  • People may not believe earthquakes will happen again there
21
Q

How are buildings made to withstand earthquakes?

A
  • Base isolators for shock absorption
  • Weights to sway building side to side with movement of ground
  • Walls reinforced with steel so they don’t shatter as easily
22
Q

What are the secondary effects of a volcano?

A
  • Minerals deposited by lava create fertile soils for farmers= higher yield = more income
  • Tourists attracted = more money for economy
  • lahars caused by pyroclastic flows
  • Loss of buildings = homeless/jobless
  • Food water shortages
  • Roads/ railways blocked so supplies can’t get in
23
Q

how to reduce impact of volcanoes?

A
  • Predict using modern technology = more accurate
  • If you can predict, you can evacuate faster
  • Building planning to not build in danger areas
  • Aid from foreign countries and government
24
Q

Why do people live near volcanoes?

A
  • Tourists= more jobs= more money
  • Fertile soils = more crops can be grown= more money
  • Geothermal energy for homes
  • Mining for rich minerals
25
Q

What is the Richter Scale?

A

It is a base 10 logarithmic scale measuring the magnitude of an earthquake. Each value is 10 times more than the previous one.

26
Q

What is magnitude?

A

The size of the earthquake depending on the amplitude of the seismic waves. It is the amount of energy released.

27
Q

What is the intensity of an earthquake?

A

Intensity refers to the extent of damage done to people and infrastructure etc

28
Q

What is the epicentre of an earthquake?

A

It is the point above the focus on the surface of the earth

29
Q

What is the focus(hypocentre)?

A

The point underground where the earthquake/ fault movement actually happened

Geography (6 decks)

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