The Restless Earth Flashcards

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1
Q

How thick is the earths crust?

A

60-70km, 5-8km

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2
Q

What temperature is the earths mantle?

A

400•C - 2000•C

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3
Q

What state is the earths mantle?

A

Semi-solid

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4
Q

What temperature is the earths outer core?

A

2000-2500

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5
Q

What state is the earths outer core?

A

Liquid

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6
Q

What temperature is the earth inner core?

A

2500-3000

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7
Q

What state is the earth inner core?

A

Solid

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8
Q

What is the earth inner core made of?

A

Iron and nickel

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9
Q

What are the thinnest and thickest layers in the earths structure?

A

Thinnest- crust

Thickest- mantle

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10
Q

Name the 8 plate boundaries

A

African

Antarctic
Eurasian
Nazra
Indo- Australian
North-American
South-American
Pacific

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11
Q

Name the 3 types of plate boundaries

A

Constructive (divergent)

Destructive (convergent)
Conservative (wrench/tear/fault)

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12
Q

Formation of constructive plate boundaries

A
  1. Convection current pulls plates apart
  2. Mantle rises through plates
  3. Magma solidifies and makes new material
  4. Underwater volcano/oceanic ridge formed
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13
Q

Two types of destructive plate boundary

A
  1. Subduction
  2. Collision
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14
Q

Formation of subduction plate boundaries

A
  1. Oceanic plate is more sense so it sinks below continental plate
  2. Oceanic plate melts making it’s less dense than the continental plate
  3. Oceanic plate rises and creates volcano
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15
Q

Formation of collision plate boundaries

A
  1. Two plates of same density are pulled together by convection current
  2. They collide and push up to form fold mountains
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16
Q

Conservative plate boundaries

A
  1. Two plates slide past each other at different speeds (same or different direction)
  2. Friction created
  3. Plates finally jerk past each other release tension and energy
17
Q

3 types of volcanoes

A
  1. Shield volcano
  2. Dome volcano
  3. Composite volcano
18
Q

Shield volcanoes

A
  • gently sloping sides
  • low silica content
  • runny lava
  • erupt frequently but gently
  • oceanic ridges
19
Q

Dome volcanoes

A
  • steep, convex sides
  • high silica content
  • viscous and acidic lava
  • erupt less frequently and violently
20
Q

Composite volcano

A
  • have a secondary/parasitic vent
  • alternate layers of ash and lava
  • look like come volcano
  • when main vent is blocked a secondary develops
  • erupt v. infrequently but v. violently
21
Q

How to monitor/predict volcanoes

A
  • testing gases
  • measurement of land
  • tutmeters measure changes in angles
  • flow can be predicted
  • robots can be sent into volcanoes to test soil/rock changes
22
Q

Super volcanoes

A
  • much bigger
  • emit 1000km^3 of material
  • appear as large depressions/calderas
23
Q

Formation of super volcanoes

A
  1. Rising magma can’t escape
  2. Large bulge forms
  3. Cracks on surface of bugle emit gas
  4. Roof of magma chamber collapses and large depression forms
24
Q

Earthquakes

A

Occur when plates move at major fault lines

25
Q

Which plate boundaries do earthquakes occur at

A

All 4 types, mainly destructive+constructive plate boundaries

26
Q

What scales are used to measure earthquakes

A

Mercalli scale and Richter scale

27
Q

Name of device which ensures magnitude of earthquake

A

Seismograph

28
Q

Richter scale is a _____ scale

A

Logarithmic

29
Q

Focus point

A

Where ye rock moves and seismic waves are produced

30
Q

Epicentre

A

Directly above the focus point on the earths surface

31
Q

6 variables which determine earthquake damage

A

1 size

2 emergency services
3 buildings
4 time of day
5 education
6 physical landscape

32
Q

Monitoring and predicting earthquakes

A
  • geologists measure earths activity around the world
  • tremors plotted by geological surveys on major fault lines
33
Q

Preparing for earthquakes

A
  • education in MDCs
  • houses interiorly designed to withstand earthquakes
  • buildings built to withstand earthquakes (low centre of gravity)
  • emergency services well prepared
34
Q

Tsunamis

A

Total waves which are triggered by an underwater earthquake

35
Q

What speed to tsunamis travel at?

A

400-600 kph

36
Q

What’s the primary and secondary effect of a tsunami?

A

Primary- displacement of oceanic plate

Secondary- displacement if water

37
Q

How far will 2 crests be from each other in a tsunami?

A

Regular wave- 100m

Tsunami- 200km