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Tectonic Processes And Hazards > 1.1 > Flashcards

1.1 Flashcards

1
Q

What is the Lithosphere

A

The lithosphere is the crust and the top layer of the mantle (solid)

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2
Q

What is plate tectonic theory

A

Theory created by Alfred Wegener in 1912 he suggested that tectonic plates move

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3
Q

Why do plates move

A

1) mantle convection currents
2) slab pull
3) subduction zone movement
4) sea floor spreading

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4
Q

List the characteristics of the crust

A
  • Up to 400 degrees
  • Its solid
  • It’s the layer we live on
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5
Q

List the characteristics of mantle

A
  • Up to 870 degrees
  • Less dense
  • Upper part is solid. Lower part is semi-molten
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6
Q

List the characteristics of the outer core

A
  • 4400 to 6100 degrees
  • Dense
  • Liquid iron and nickel
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7
Q

List characteristics of the inner core

A
  • 7000 degrees
  • Very dense
  • Solid (radiates heat)
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8
Q

What are the processes at Divergent Processes

A

Sea floor spreading - rising magma

Large number of shallow focus earthquake

Plates moving apart from one another

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9
Q

What are the land forms found at divergent plate boundaries

A

Shield volcanoes

Rift valleys

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10
Q

Characteristics of Convergent plate boundaries

A

Plates move towards each other

One slides below the other (oceanic) - high magnitude earthquakes

This is called a subduction zone

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11
Q

What is a volcanic hotspot

A

Volcano that exists in the middle of a plate

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12
Q

What is a mantle plume

A

Long-lived areas of high levels of heat flow within the mantle

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13
Q

Give three examples of volcanic hotspot islands

A
  • Hawaiian islands
  • Galapagos islands
  • Canary islands
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14
Q

How old is the Hawaii Emperor Sea Mount Chain

A

5.6 million years ago, to now

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15
Q

What is the major type of volcano found in Hawaii

A

Shield volcano - non eruptive

  • gentle slope
  • low viscosity - lava flows easily & quickly
  • frequent eruptions
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16
Q

Explain the reasons for the shape of Hawaii’s volcanoes

A

Because the volcanoes are not explosive eruptions, the lava easily and gently flows out and hardens creating gentle slopes

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17
Q

Why does the hot spot stay in the same place

A

Magma finds weaknesses in the lithosphere and hardens on sea floor

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18
Q

Suggest why there is a sharpe bend in the Hawaiian Island chain

A

Plate movement changes

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19
Q

Intra-plate activity

A

Occurring within the middle of a plate

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20
Q

What does Viscosity mean

A

How sticky

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21
Q

What were the three different suggestions of Alfred Wegener - Pangea

A

He suggested:
•Biological
•Geological
•climatological

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22
Q

Biology evidence of Pangea

A
  • Mesosaurus - small reptile. Fossils and remains found in South America & Africa
  • A plant which existed when coal was being formed has been located in India and Antarctica
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23
Q

Geology evidence of Pangea

A

•Rocks f similar age, type, structure and formation found in South Africa and Brazil

24
Q

Climatology evidence for Pangea

A
  • Coal found under Antarctic ice cap

* Evidence of glaciation in Brazil and India

25
Q

What is an Earthquake

A

Sudden shaking of the ground

26
Q

Where do Earthquakes happen

A

Along plate boundaries

27
Q

Why do Earthquakes happen

A

Release of friction/tension of the plates

Caused by sudden movements near the Earth’s surface along a fault

28
Q

What is a fault

A

A fracture in the rocks that make up the Earth’s crust

29
Q

What is the Epicenter

A

The point at the surface of the Earth directly above the focus

30
Q

What is the Focus

A

The point within the Earth where an earthquake rupture starts

31
Q

What are seismic waves

A

Waves that transmit the energy released by an earthquake

32
Q

List the characteristics of P-Waves

A

‘P’ =pressure

  • Travel fast
  • First waves to arrive
  • No one knows they’ve passed
  • Send vibrations, push & pull weakening the rock
33
Q

List the characteristics of S-Waves

A

‘S’ =Secondary

  • Travel slow
  • Pulling rock side to side
  • People can feel this
  • Cause damage
34
Q

Like the characteristics of a Surface Wave (L-Wave)

A
  • Large
  • Move left and right , up and down
  • Buildings fall
35
Q

What factors can increase the severity of an earthquake

A
  • Hospitals being built furthest away on cheap land
  • Old buildings, weak - quality comes down to wealth (e.g) Nepal
  • Buildings closest to river - geology type, softer rock, shakes for longer
36
Q

What are the characteristics of a Shield Volcano

A
  • Non eruptive
  • Gentle slopes
  • Low viscosity - lava flows easily and quickly
  • Frequent eruptions
37
Q

What are Primary effects of an Earthquake

A
  • Ground shaking (which causes infrastructural damage)

* Crustal fracturing

38
Q

What are Secondary effects of an Earthquake

A
  • Liquefaction
  • Landslides/Avalanches
  • Tsunami
  • Aftershocks
39
Q

What is Liquefaction

A

When land shakes so much the solid particles start to act like a liquid

40
Q

What are the 7 main factors which increase the severity of volcanic hazards

A

1) Viscosity of the magma - high viscosity = high explosivity
2) Plate margins - convergent margins are the most dangerous
3) Explosiveness
4) The material ejected
5) Distance to populated area
6) Frequency
7) Prediction

41
Q

How is a volcanic eruption measured?

How is it measured?

A

•Volcano Explosivity Index

It is calculated using the ash cloud height and the volume of products ejected into the air

42
Q

Characteristics of Composite volcano

A
  • Steep sides
  • Formed from very thick, viscous lava that doesn’t flow easily
  • Lava builds up around the vent
  • Explosive eruptions relating to viscosity of magma (gases can’t escape)
43
Q

Characteristics of Shield volcano

A
  • Gentle slopes, shield shape
  • Low viscosity- lava flows easily and quickly
  • Gentle, non-explosive eruptions
  • Frequent eruptions (Hawaii)
44
Q

Primary effects of a Volcano

A
  • Pyroclastic Flow
  • Lava Flows
  • Tephra and Ash Cloud
  • Gas eruptions
45
Q

Secondary effects of a volcano

A
  • Lahars

* Jokulhaups

46
Q

What is a Pyroclastic Flows (Primary)

A

A dense, destructive mass of very hot ash, lava fragments and gassed ejected explosively from a volcano and typically flowing at a fast speed

47
Q

What is a Lava Flow (Primary)

A

A mass of flowing or solidified lava

48
Q

What is Tephra and Ash Fall (Primary)

A

All explosive volcanic eruptions generate tephra and produce ash

Fragments of rock is explosively ejected

49
Q

What are Gas eruptions (Primary)

A

Gases that are released during volcanic eruptions

50
Q

What are Lahars (Secondary)

A

Volcanic mudflow on the slopes of a volcano

51
Q

What are Jokulhlaups (Secondary)

A

Glacier - typical of glacial outburst flood

52
Q

Why do mudflows occur

A

When volcanic material mixes with rain and flows

53
Q

Why do eruptions occur

A

When pressure forces magma from chamber to main vent crater blown off

54
Q

What is formed when lava cools

A

New rock / land

55
Q

Characteristics of a Tsunami

A
  • Often low in height out at sea (below 300mm)
  • Grow in height as they hit shallow water
  • A series of waves
  • First wave not necessarily the largest or most destructive
  • Long wavelength can mean up to an hour between waves

Tectonic Processes And Hazards (2 decks)

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