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Year 9 > Geography - Earthquakes and Volcanoes 🌋 > Flashcards

Geography - Earthquakes and Volcanoes 🌋 Flashcards

1
Q

What are the 4 layers of the earth?

A

The inner core, outer core, mantle, and crust

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2
Q

What is the thinnest layer of the earth?

A

The crust

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3
Q

How thick is the crust?

A

Between 8 to 40km thick.

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4
Q

What are the 2 types of crust?

A

Oceanic crust and continental crust.

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5
Q

How thick are both types of crust?

A

Oceanic crust is about 7km thick; Continental crust is about 30-50km thick, but oceanic crust is denser.

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6
Q

What is the continental crust made of?

A

Granite

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7
Q

What is the oceanic crust made of?

A

Basalt

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8
Q

How thick is the mantle?

A

About 2900km thick.

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9
Q

Is the mantle solid?

A

No, it is semi molten. The upper mantle is hard, but the lower mantle has soft rock, runny in places.

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10
Q

What is the lithosphere?

A

The hard part of the earth: containing the upper mantle and the crust.

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11
Q

What is the core made of?

A

The core is made of iron and nickel.

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12
Q

What differentiates the outer and inner core?

A

The outer core is liquid, but the inner core is solid.

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13
Q

Why is the inner core solid?

A

The pressure from all the other layers forces the inner core to be solid.

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14
Q

What are convection currents?

A

Powerful currents of flowing magma, in the mantle, that move in a circular motion, that causes plates to move.

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15
Q

What are plates?

A

The parts of the earth that are split into huge slabs, their movements cause earthquakes and eruptions.

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16
Q

Where do volcanos typically occur, and earthquakes frequently occur on earth?

A

Along plate margins. (or hotspots!!)

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17
Q

What are the 4 types of plate margins?

A

Constructive, Conservative, Destructive with oceanic and continental plates, and Destructive through collision.

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18
Q

What is a constructive plate margin?

A

When two plates are moving away from each other, causing magma to make way to the surface, cool, and create new land (volcanos)

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19
Q

What is a conservative plate margin?

A

When two plates slide against each other, this causes vibrations, tremors, and earthquakes.

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20
Q

What is a destructive plate margin with oceanic and continental plates?

A

When an oceanic and continental plate move towards each other. The oceanic plate usually moves under the continental plate since it’s denser, and feeds the rocks into continental plates, creating more magma. It going under is called subduction.

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21
Q

What is a destructive plate margin through collision?

A

When two continental plates move towards each other. This can create mountains.

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22
Q

What kind of mountain is created when two continental plates collide?

A

Fold mountains.

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23
Q

What are earthquakes?

A

Earthquakes are vibrations caused by Earth’s movements at plate margins and at major fault lines.

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24
Q

Where are the most severe earthquakes caused?

A

At conservative and destructive margins.

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25
Q

What is strain energy?

A

When powerful forces push plates together, the pressure stored is called strain energy.

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26
Q

What happens when strain energy is released?

A

The pressure gets too much, and one rock slips upwards. This releases the energy in seismic waves, which pass through through earth and shake everything - this is an earthquake.

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27
Q

What is the focus in an earthquake?

A

The point where the seismic waves are released.

28
Q

What is the epicenter in an earthquake?

A

The point directly above the focus at the earth’s surface.

29
Q

What is an aftershock?

A

After the rock that slid up in the earthquake settles, there are smaller earthquakes called aftershocks.

30
Q

What is the scale used to measure earthquakes?

A

They are measured using a The Richter Scale, a logarithmic scale that means each level is has 10x more shaking than the last. Also 30x more energy than the last one.

31
Q

What is the instrument used to measure tremors?

A

A seismograph.

32
Q

What damage can be done by earthquakes?

A
  • Landslides block roads
  • Buildings and bridges topple
  • Roads split open
  • Gas pipes are torn down, which causes fires.
  • Tsunamis can form from an underwater earthquake.
33
Q

What was the sichuan earthquake?

A

An earthquake in southwest china. It was a 7.9 on the Richter scale.

34
Q

What caused the sichuan earthquake?

A

The Indo-Australian plate pushing into the Eurasian plate.

35
Q

What are the 3 ways to reduce effects of earthquakes?

A

Prediction, Protection, and Planning

36
Q

How does prediction help reduce effects of earthquakes?

A

Scientists can use historical evidence and monitoring to make predictions of when and where an earthquake is.

37
Q

How does Protection help to reduce effects of earthquakes?

A

People can design buildings and infrastructure that withstand the ground during an earthquake.

38
Q

How does planning help reduce the effects of earthquakes?

A

People can identify and avoid places where there is risk of earthquakes?

39
Q

How can scientists predict earthquakes?

A

There aren’t any warning signs, so its not very easy. But by looking at historical records, scientists can identify places at risk.

40
Q

What are some ways that people can protect buildings from earthquakes?

A
  • Buildings can be built with more stable shapes.
  • Shock resistance can be used - for example bamboo is a very shock resistant material, and shock absorbers.
  • Deep foundations
41
Q

What is a tsunami?

A

A big earthquake in the ocean floor that causes waves to be sent in all directions.

42
Q

What causes a tsunami wave?

A

After an earthquake, land is vertically shifted up, which raises the water and creates the wave.

43
Q

What was the tsunami that occured in december of 2004?

A

It was an earthquake that occured in the Indian ocean, affecting 15 countries.

44
Q

After the 2004 tsunami, what was done to warn people of future tsunamis?

A

Sirens were installed to warn people.

45
Q

What is a volcano?

A

A place where liquid rock or magma shoots up or erupts through the ground.

46
Q

What are the 3 states of a volcano?

A
  • Active - Has erupted recently and is likely to erupt
  • Dormant - Has not erupted in 2000 years
  • Extinct - Will never erupt again (Extinct volcano be like haha you thought - guess what imma ERUPT MWAHAHAHA, you mortals are FOOLED!!!)
47
Q

Where does all the magma that erupts from a volcano come from?

A

It comes from a magma chamber.

48
Q

What is the main vent/conduit of a volcano?

A

The main “tube” that leads to the crater.

49
Q

What is a secondary vent in a volcano?

A

A secondary tube branching off of the main vent that leads to a smaller opening.

50
Q

What is the throat of a volcano?

A

A slightly thicker part at the end of a volcano, that leads to the main opening/crater.

51
Q

If lava is thick and gassy, how does it leave a volcano?

A

It is hard to leave the volcano, so pressure builds up and it explodes out.

52
Q

What is an ash cloud?

A

A heavy cloud above a volcano formed when magma is shot out, and contains rock mixed with scorching gases like carbon dioxide and sulfur dioxide.

53
Q

What is a pyroclastic flow?

A

A deadly flow that flows down the slope of a volcano when an ash cloud collapses.

54
Q

What is viscous magma?

A

Magma can be viscous and thick, or super runny - it depends on the rock melted in the magma.

55
Q

What does lava that exploded out form?

A

Igneous rock, commonly basalt, and if the lava was thick and gassy then it would form pumice.

56
Q

What does cooled lava normally form?

A

Basalt.

57
Q

What is volcanic gas made of?

A

Carbon dioxide, sulfur, and some other gases. It can suffocate you. It smells of rotten eggs if you wanted to know.

58
Q

What is a mudflow?

A

It’s formed when a pyroclastic flow gets mixed with water.

59
Q

What is a composite or strato volcano?

A

A volcano with steep slopes. It has high gas pressure and can cause violent eruptions. They are made up of alternating layers of lava and ash.

60
Q

What is a shield volcano?

A

A volcano with gentle slopes. It is formed from frequent eruptions of thin, runny, basaltic lava. It’s made of layers of lava.

61
Q

What damage can eruptions do?

A
  • Pyroclastic flows scorch everything.
  • Mudflows sweep everything along, and drown you in mud
  • Lava flows destroy crops, and bury towns and villages.
  • Blankets of ash can weigh down planes, roofs, and ruin crops.
  • Volcanic gas forms acid rain
  • The ash can suffocate you
    Have fun!
62
Q

What speed do pyroclastic flows and mudflows travel at?

A

Pyroclastic flows can travel at 200km/hour. Mudflows can travel at 100km/hour.

63
Q

What country was made by volcanos?

A

Iceland.

64
Q

How was iceland formed?

A

The North American and Eurasian plates were pulling apart, Making volcanos form. Most of them are underwater, but extra magma was spurted at iceland - it’s fed by a current of magma called a plume,

65
Q

Why do people go to / live in iceland when its LITERALLY A VOLCANO???

A
  • It has stunning scenery.
  • It has hot spring and geysers which attract tourists.
  • The heat can be harnessed for geothermal energy
66
Q

Why do people live in danger zones with volcanos?

A
  • They have good soil for farming
  • People can make money from tourism
  • Geothermal energy
  • Valuable materials are found in extinct volcanos.
  • Plate movements push rock upwards, which have fossil fuels.
  • People are use to life there
  • They were born there, and can’t afford a new place.
  • It’s beautiful!

Year 9 (23 decks)

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