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Geography > Tectonic hazards + earthquakes > Flashcards

Tectonic hazards + earthquakes Flashcards

1
Q

What is the first key theory?

A

Mantle convection

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2
Q

What is mantle convection?

A

Mantle gets hot, rises , moves in circular motions and these currents drag along the plates and make them move

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3
Q

What is the name of the circular currents?

A

Convection currents

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4
Q

Where do convection currents occur?

A

Under the crust

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5
Q

What is the second key theory?

A

Slub pull, ridge push

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6
Q

What happens in slab pull, ridge push?

A

Convection currents in the mantle cause will create a new oceanic crust at divergent boundaries.

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7
Q

What is the downward movement in slab pull, ridge push called?

A

Subduction

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8
Q

What is slab pull?

A

Oceanic crust cools and thickens, and pushes down as magma emerges form behind it.

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9
Q

What is ridge push?

A

Gravitational force, sinking material pulls the plate down.

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10
Q

What is the third key theory?

A

Sea floor spreading

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11
Q

What is sea floor spreading?

A

Continuous process of forming new igneous rock at mid ocean ridges.

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12
Q

What type of salt is produced at sea floor spreading?

A

Basalt

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13
Q

What processes happen at oceanic/oceanic divergence?

A

Upwelling magma
Divergence
Spreading eg sea floor

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14
Q

What landforms are found at oceanic/oceanic divergence?

A

Mid ocean ridge
Valleys in the centre of the ridge
Submarine volcanoes

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15
Q

Whats an example of an oceanic/oceanic divergence?

A

Mid Atlantic ridge

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16
Q

What is continental/continental divergence?

A

Sections are moving in different directions and therefore fracturing the crust causing valleys.

17
Q

What is the example of the continental/continental divergence?

A

Great African rift valley

18
Q

What are conservative margins?

A

Passive margins

Strike-slip boundaries

19
Q

What are the primary hazards of volcanoes?

A

Lava flows
Tephra
Pyroclastic flows
Poisonous gases

20
Q

Name some characteristics of lava flows?

A

Least explosive
Often slow flowing
Nyiragongo - primary problem

21
Q

Name some characteristics of pyroclastic flows?

A

Mixture of hot rock, lava and gases
Between 350-1000 degrees
Can move at 200m/s

22
Q

Name some characteristics of tephra?

A

Rock fragments

Range between 2mm and 1m in diameter

23
Q

Some examples of poisonous gases

A

CO2
Carbon monoxide
Hydrogen sulphate
Chlorine

24
Q

What are the secondary hazards of volcanoes?

A

Lahars
Debris avalanches
Flooding
Tsunamis

25
Q

What are Lahars?

A

Mixture of hot and cold water with rock fragments

AKA debris flows

26
Q

What are mudflows?

A

Mixture of sediment and water
Speeds of up to 60km/h
Highly erosive

27
Q

What are debris avalanches?

A

Oversteeped slopes become gravitationally unstable leading to sudden slope failure

Geography (13 decks)

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