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Geography > Plate Tectonics > Flashcards

Plate Tectonics Flashcards

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1
Q

How much do plates move per year?

A

About 8 cm

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2
Q

The earth consists of four concentric plates ,what are they?

A

Inner core
Outer core
Mantle
Crust

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3
Q

The crust is made up of tectonic plates, which are in constant motion. What are tectonic plates?

A

Large areas of the earths crust that move slowly on the upper part of the mantle, often colliding and moving away from each other.

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4
Q

Where are earthquakes and volcanoes are most like to occur?

A

At plate boundaries

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5
Q

What is the inner core

A

The centre of the earth, it is the hottest part and made up of iron and nickel with temperatures up to 5500 degrees.

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6
Q

What is the outer core?

A

This is the layer surrounding the Inner core. It is a liquid layer, also made up of iron and nickel. It is extremely hot with similar temperatures to the inner core.

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7
Q

What is the mantle?

A

The widest section of the earth. It has a thickness of approx 2900km. The mantle is made up of semi molten rock called magma. In the parts of the mantle the rock is hard but in the lower parts it is soft and beginning to melt.

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8
Q

What is the crust?

A

The outer layer of the earth. It is a thin layer between 0-60km thick. We live upon it.

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9
Q

What types of crusts are there? And which one is thicker?

A

Continental crust-carries land
Oceanic crust- carries water
The continental one is thicker.

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10
Q

Heat rising and falling inside the mantle creates convection currents generated by radioactive decay in the core. These convection currents move the plates. Where convection currents diverge near the earths crust what happens to the plates?

A

They move apart.

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11
Q

What happens to the plates when convection currents converge?

A

They move towards each other.

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12
Q

What is a destructive plate boundary and what happens there?

A

This occurs when oceanic and continental plates move together. The oceanic plate is forced under the lighter continental plate. Friction causes melting of the oceanic plate and may trigger violent earthquakes, due to the increase of pressure. Magma rises up through the cracks and forms volcanoes. Violent volcano eruptions can occur here.

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13
Q

What is a constructive plate boundary and what happens there?

A

This is when two plates move apart. Magma immediately rises to fill any gap and forms a new oceanic crust. Mild volcanoes eruptions and eruptions can occur.

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14
Q

What is a collision plate boundary and what happens there?

A

At a collision plate boundary two continental plates move together. As continental crusts can’t sink the rocks between them are forced upwards to form fold mountains. Only earthquakes can take place here.

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15
Q

What is a conservative plate boundary and what happens there?

A

At these boundaries two plates slide past each other. They rub together and cause friction build up. No new land is formed nor destroyed. Severe earthquakes can occur due to the shock waves.

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16
Q

What are convection currents?

A

Movements within the earths mantle caused by heat of the core.

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17
Q

How did Pangea separate?

A

The continents were formed due to the mantle convection within the earths surface , new material constantly came up between the earths tectonic plates at rift zones causing them to move away from the rift towards one another.

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18
Q

What evidence is there that the continents were once all joined together?

A

Evidence was that the earths continents seem to fit together like a jigsaw puzzle in many areas around the globe. Other evidence would be fossil and species distribution, distinctive patterns are seen where the continents divided. Matching fossils have been found I’m Africa and South Africa indicating that these species lived very close to each other.

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19
Q

What is an earthquake?

A

A sudden movement of the earths crust caused by the release of stress accumulated along geographical faults or by volcanic activity.

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20
Q

What is a Richter scale?

A

This is a 10 point scale that measures the strength of the earthquake.

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21
Q

What is an epicentre?

A

The centre of the earthquake and the strongest part?

22
Q

How do we feel an earthquake? How are they released?

A

Earthquake energy is released in seismic waves. These waves spread out the focus. The waves are felt most strongly at the epicentre, becoming less strong as they travel further away. The most severe damage caused by an earthquake will happen close to the epicentre.

23
Q

What date did the Kobe ,japan earthquake happen?

A

17th January 1995

24
Q

How strong was the earthquake?

A

7.2

25
Q

What were the social impacts on people? Give long and short term effects.

A

Short term: people injured, homes destroyed, transport and communication links disrupted, water pipes bursted and may be contaminated.

Long term : disease may spread. People may have to be re housed.

26
Q

Give long and short term economic effects.

A

Short term: shops and businesses destroyed, looting may take place, trade can be difficult due to damaged transport.

Long term: the cost of rebuilding settlement is high, income could be lost.

27
Q

Give short and long term environmental effects.

A

Short term: built landscape would be destroyed, fires can spread due to gas pipe explosions.

Long term: important natural and human landscapes may be lost.

28
Q

How is a volcano formed?

A
  1. Magma rises through cracks or weaknesses In the earths crust.
  2. Pressure builds up inside the earth.
  3. When this pressure is released, magma explodes to the surface causing a volcanic eruption.
  4. The lava from the eruption cools to form a new crust.
  5. Over time after several eruptions, the rock builds up and a volcano forms.
29
Q

What is a magma chamber?

A

A collection on magma inside the earth below the volcano.

30
Q

What is the main vent?

A

The main vent is the main outlet for the magma to escape.

31
Q

What are secondary vents?

A

Smaller outlets through which magma escapes.

32
Q

What is the crater?

A

The top of the volcano created after an eruption blows the top off the volcano.

33
Q

Give the 4 characteristics of a shield volcano.

A
  1. Usually found at constructive boundaries
  2. They are low, with gently sloping sides
  3. They are formed by eruptions of thin, runny lava
  4. Eruptions tend to be frequent but relatively gentle
34
Q

Give the 3 characteristics of a composite volcano.

A
  1. They are made up of alternating layers of lava and ash
  2. They are usually found at destructive boundaries
  3. The eruptions from these volcanoes may be a pyroclastic flow rather than a lava flow. A pyroclastic form is a mixture of hot steam, ash, rock and dust.
35
Q

Why do people live near a volcano?

A 
Lots of food resources growing
Near sea- water
Large amounts of free space
Fertile soil 
Good tourist attraction
Geothermal energy from the volcano 
Mining 
Natural springs
36
Q

What can lava do which is very important and useful?

A

Lava can crystallise to form minerals like gold, silver and diamonds depending on their composites.

37
Q

Describe the distribution of earthquakes around the world

A

The earthquakes are found mainly on the plate boundaries where there are faults in the crusts. They are here because the most pressure builds up between plate boundaries.

38
Q

Why do earthquakes sometimes happen in the same location as volcanoes?

A

It is due to the plate boundaries, destructive boundaries can trigger both in an act of violent forms. The plates will not only build up pressure in the mantle but they will also shake, causing both to happen.

39
Q

How can we make earthquakes less of a hazard? Use the PPP prediction , protection, preparation (6marks)

A
  • We can try and predict when an earthquake is going to happen by installing alarms that trigger off in the mildest of tremors.
  • For protection we could introduce a different building structure
40
Q

What is the Richter scale?

A

The ten point scale that measures the strength of the earthquake.

41
Q

What is the focus?

A

The point of the earthquake where the rock actually breaks. This is usually found far beneath the surface if the earth.

42
Q

Describe the distribution of earthquakes around the world.

A

The earthquakes are distributed very closely around the coast and in central cities, they are located on plate boundaries.

43
Q

Why do earthquakes sometimes happen in the same location as volcanoes?

A

It’s due to the plate boundaries ;destructive boundaries can trigger both in violent forms. The plates will not only build up pressure in the mantle but they will also shake, causing both to happen.

44
Q

Give three reasons why some earthquakes cause more deaths than others.

A

It depends on the strength of the earthquake
If it’s in the city, with lots of buildings then there’s a risk of them falling
Depends where they’re living, if it’s somewhere where wind is minimal and it’s mild/ hot all year round the homes wouldn’t have to be so sturdy.
Rural or urban
It depends if the country is a medc or a ledc, then they won’t have the money to build withstanding tremor buildings from more expensive materials.

45
Q

What was the world called before the continents split?

A

Pangea

46
Q

What’s magma

A

Molten rock inside the volcano

47
Q

What’s lava

A

Molten rock in a volcano

48
Q

How are fold mountains formed give an example

A

When two continental plates come together and are forced into mountains
Eg Himalayas

49
Q

How are earthquakes and volcano eruptions called

A

Continental and oceanic plates coming together.

50
Q

How are shield volcanoes formed

A

By eruptions of thin runny lava from shield volcanoes .

51
Q

What is Lahar

A

A type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water.

52
Q

What is a pyroclastic flow

A

A fast moving current of hot gas

Geography (6 decks)

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