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Restless Earth and Water on Land > Part A Restless Earth > Flashcards

Part A Restless Earth Flashcards

1
Q

Name the four layers that make the earth’s structure

A

Inner core, outer core, mantle and crust

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2
Q

What is the inner core made out of and how hot is it?

A

It is made out of nickel and iron and is 5500*c

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3
Q

Name some of the plates that make the earth’s crust

A

North American, Nazca, African plate, Eurasian, Antarctic and Indo Australian plate

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4
Q

What is a destructive-subduction plate margin?

A

Oceanic plate moves into and subducts beneath continental plate

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5
Q

Name an example of a destructive-subduction plate margin

A

Juan de Fuca Plate (oceanic) sbduts beneath the North American Plate (continental)

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6
Q

What is a destructive-collision plate margin?

A

When two continental plates collide

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7
Q

Name an example of a destructive-collision plate margin

A

Eurasian plate and African plate (forms Himalayas)

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8
Q

What is a constructive plate margin?

A

When two plates move away from each other

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9
Q

Name an example of a constructive plate margin

A

African plate and South American plate

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10
Q

What is a conservative plate margin?

A

When two plates slide alongside each other

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11
Q

What are the features of a continental plate?

A
  • It is older than a oceanic plate, most continental plates are over 1500 million years old.
  • The cannot sink
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12
Q

What are the features of an oceanic plate?

A
  • They are denser

- Can be renewed and destroyed

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13
Q

What is a convection current?

A

They are the circular currents of heat in the mantle. Convection currents determine the direction of the plate margin

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14
Q

What happens at a destructive-subduction plate margin?

A
  • The oceanic plate subducts underneath a continental plate due to the constant pressure and also the oceanic plate being denser.
  • Then friction and heat from the mantle melts the plate causing it to turn it into magma, forcing it upwards to create a volcano.
  • Earthquakes occur due to friction at epicenter of the subducting plate.
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15
Q

What happens at a constructive plate margin?

A
  • When two oceanic plates move apart the magma underneath rises due to eruptions over time causing it to solidify.
  • Thus creating an underwater volcano. Over thousands of years, many volcanoes forms between the plates an island.
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16
Q

What happens at a conservative plate margins?

A

When two plates slide past each other, for example Pacific plate and North American plate causing extreme amount of friction forming an earthquake.

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17
Q

Explain how fold mountains are formed

A
  • Geosynclines are huge depressions fund naturally on the ocean floor
  • Oceans deposit sediment in these geosynclines
  • Sediment are compressed and turned into sedimentary rocks like limestone
  • Sedimentary layers are forced upwards into fold mountains
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18
Q

At what plate margin do fold mountains occur?

A

Destructive- collision and destructive-subduction plate margins

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19
Q

Where are ocean trenches found?

A

At destructive-subduction plate margins

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20
Q

How do people use the Alps in the tourist industry?

A

Tourism- skiing main source of income, in the summer there are lakeside resorts that are very popular due to the beautiful scenery.
-It’s central location between Europe’s most affluent countries provides a steady stream of tourists all year round

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21
Q

How do people use the Alps in the mining industry?

A
  • From the folding of sedimentary rock, minerals, stones and precious stones are found of the Earth’s surface
  • Thin soils- easy mining of metals and minerals (Austria, Alps lots of gold deposits)
  • Horizontal tunnels (adits) and pen-cast mining is used
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22
Q

How is hydro electric power used in the Alps?

A
  • Use of river water to produce electricity
  • Due to the steep V shaped valleys- easier to dam (rivers)
  • Dams are built across rivers, flows of water through the dam drives turbine and creates electricity
  • High rainfall, high river distance from melting glaciers and fast flowing rivers all help to generate hydro electric power (HEP)
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23
Q

How is farming used in the Alps?

A
  • Mainly dairy farming
  • Traditionally farmers used system called transhumance
  • Transhumance- seasonal movements of live stock
  • Few farmers- transhumance today
  • Valley farming- more sheltered, soils here are deeper and cattle herds
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24
Q

What are composite volcanoes made out of?

A

They are made from andesite (a viscous lava)

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25
Q

What are the features of a composite volcano?

A

They are steep sided, tall and highly explosive volcanoes

26
Q

Explain how a composite volcano erupts

A
  • Andesite lava moves slowly up from the magma chamber, gets trapped in the main vent and creates a lava dome.
  • A lava dome acts like a plug and builds up pressure in the chamber beneath
  • The lava erupts under pressure as gas, steam and pyroclastic surges
27
Q

What are shield volcano made from?

A

They are made out of basalt (a non-viscous lava)

28
Q

What are the features of a shield volcano?

A

They are gentle sided, flat and non-explosive volcanoes

29
Q

Explain how a shield volcano erupts

A

-Basalt lava moves quickly up from the magma chambers and flows unimpeded, often continuously, out of the main vent

30
Q

What does VEI stand for?

A

Volcanic Explosity Index.It is a power scale for volcanic eruptions

31
Q

Where does a basalt eruption lie on the VEI scale?

A

VEI 0-3

32
Q

Where does a andesite eruption lie on the VEI scale?

A

VEI 4-7

33
Q

Where would a super eruption lie on the VEI scale?

A

VEI 8

34
Q

How are shield volcanoes formed?

A

At constructive plate boundaries, shield volcanoes can be created. Due to the two plates margins pulling apart, magma rises causing when reached to air to solidify and create the gentle slope.

35
Q

Where is Mt. St Helen’s located and when did it last erupt?

A

It is in Washington State in the Pacific North West region of the USA. On May 18, 1980 at 8:32 am

36
Q

What caused Mt. St. Helen’s do erupt?

A

An earthquake triggered a landslide that results in Mount St Helens erupting. The volcano erupts sideways out of a cryptodome on west side.

37
Q

Name some of the primary effects of Mt. St Helens erupting?

A

57 people were killed
The lateral blast creates a 27km wipeout zone. Whole forests are uprooted by the blast. Some of the cedar forests were over 500 years old.
Ash and debris falls int the Toutle Rover and Spirit Lake, killing wildlife and destroying wetland habitats.

38
Q

What were some of the secondary effects of Mt. St Helens erupting?

A

Days later, ash laying on the ground mixed with rain water creates lahars- a volcanic mudflow
The ash clogged air conditioning systems and blocked roads with drifts a metre deep in places

39
Q

What were some of the immediate responses to the eruption of Mt. St Helens?

A

All planes flying across North America were grounded.
Film crews flocked to the foot of the volcano to make sure they had a front row seat
2 million gas masks were given out to residents across Washington State
America declares state of emergency

40
Q

What were some of the long term responses to the eruption of Mt St Helens?

A

3 million tourists now visit Mount St Helens every year
United States Geological Survey (USGS) now closely monitor the volcano. Tiltmeters and seismographs monitor any movements of the magma chamber and lava dome
In the following weeks, the Tourtle River had to be cleaned of all debris to prevent flooding in the future.

41
Q

What was ignored by residents and the press when Mount St Helens erupted?

A

The 8km exclusion zone set up

42
Q

What was the earthquake that triggered the landslide on the North East side of the mounth, measured on the richter scale as?

A

5.7 on the richter scale

43
Q

What does lateral blast mean?

A

Sideways blast

44
Q

How can we use GPS systems to monitor and predict eruptions?

A

Satellite imagery also detects temperature changes
GPS systems measure changes in the Earth’s structure
More than 12 GPS stations have been on or around Mt St Helen’s to measure any deformation of the ground
GPS use satellites to detect earth movement as little as 1mm

45
Q

How can tiltmeters be used to monitor and predict eruptions?

A

Identify small, subtle changes in the landscape
Detect caused by shifting magma beneath
Lava dome deformation precedes pyroclastic eruptions
The change in angle would indicate the amount of uplift or subsidence

46
Q

How can digital cameras be used to predict and monitor eruptions?

A

Monitoring through digital photography is safe and effective

Heat resistant cameras can be placed on crater rims

47
Q

How can seismographs and spectrometers be used to monitor and predict eruptions?

A

Volcanologists use a COSPEC (correlation spectrometer) to measure sulphur dioxide
Seismographs detect tremors and earthquakes
Patterns can be found in seismographs to help predict future volcanic events
Fumaroles release sulphur dioxide (which turns yellow, surrounding ground)

48
Q

What are the positive impacts of a volcanic eruption?

A

It creates fertile soils which makes it easier for farming
Increases notoriety and tourism- Mt St Helen’s receives 3 million visitors a year
Geothermal energy- meets the heating and hot water requirements of 87% of all buildings in Iceland
Source for precious and semi-precious gems- diamonds, opals and quartz
Recreation- skiing, hiking, walking tours
Household products- kitty litter, abrasive agents in toothpaste, stone-washed jeans with pumice

49
Q

How does a supervolcano occur?

A
  • Supervolcanoes experience a violent birth when a vast reservoir of magma rises from the hot spot and create intense pressure beneath the Earth’s crust.
  • As pressure from the magma chamber builds, the ground above it bulges upwards
  • Then at its breaking point, the ground can rupture in an explosion powerful enough to spew magma, ash and gases far into the atmosphere in volumes so large that debris can rain down for thousands of square miles
  • As pressure below is released, the ground collapses into the depleted magma chamber and forms a huge depression called a caldera
50
Q

What are the impacts of a super volcanic eruption?

A

Billions of tons of ash is released
The sun is blocked out
A fall in global temperature ‘global cooling’- new ice age
Crops cannot grow and die due to there being no sun
Famine, which will eventually lead to mass starvation
Resources become scarce as trade as stopped due to planes not being allowed to fly
Recession and inflation

51
Q

How does an earthquake occur?

A

Earthquakes occur when two plates slip past one another at a plate boundary. The plates get caught up due to friction, they suddenly jolt into a new position. This is an earthquake

52
Q

What is the focus?

A

The focus is where the pressure is released

53
Q

What is the epicentre?

A

The epicentre is the area above the focus, and it recievess the highest amount of energy

54
Q

What causes an earthquake to be more or less harmful?

A

If the focus is closer to the surface, the more damage is caused. A shallow focus therefore will create more destruction than a deep focus.

55
Q

What are p-waves?

A

They are the primary waves that are the fastest waves and shake the Earth backwards and forwards

56
Q

What are s-waves?

A

They are secondary waves that are slower and move with a sideways motion

57
Q

What are surface waves?

A

They travel much nearer to the surface and more slowly than P or S waves but are the most destructive. Surface waves include longitudinal waves (moving up and down) and transverse waves (moving side to side)

58
Q

What is the mercalli scale?

A

Used to measure the effects of an earthquake by subjective description

59
Q

Name some of the stages of the mercalli scale?

A

1- Felt by almost no one
4-Felt indoors by many, feels like a truck has struck the side of the building
5- Felt by everyone; many people are awakened. Swaying trees and poles may be observed
7- Everyone runs outdoors. Poorly built structures considerably damaged. Slight damage elsewhere
9- All building considerably damaged, many shift off foundations. Noticeable cracks in ground
12- Total destruction, Waves seen on ground surfaces, object are tumbled and tossed

60
Q

What were the positive impacts of the Kobe, Japan earthquake?

A

Retro-engineering- putting a stronger support framework around existing buildings- such as the red girders around Osaka Bay tower
Building Spacing- office blocks have to be a certain distance apart to stop a ‘domino effect’ if one collapses, Prevents the spread of fires
Rubber shock absorbers- bridges supports on Hanshin Expressway now have to have rubber pads to absorb the shock waves are prevent bridge and road collapse

Restless Earth and Water on Land (3 decks)

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