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Geography > Tectonic Hazards and Natural Hazards > Flashcards

Tectonic Hazards and Natural Hazards Flashcards

1
Q

What are the 4 layers of the Earth?

A

Core, crust and mantle

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2
Q

What are the two types of core

A

Inner and outer core

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3
Q

What is the inner core

A

The inner core is metallic and solid

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4
Q

What is the outer core

A

The outer core is liquid

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5
Q

What is the core

A

The core is the hottest part of the Earth’s layers

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6
Q

What is the mantle

A

The mantle surrounds the core. It is a semi solid rock and can move.

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7
Q

What is the crust

A

Another word for crust is lithosphere. The litosphere is a thin outer shell and is the layer we live on. It is between 50 to 200km thick and floats on the semi solid rock mantle. The lithosphere is also broken into large pieces called tectonic plates

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8
Q

What are the two types of tectonic plate

A

Oceanic and continental plate

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9
Q

What is the continental plate

A

They are thicker, older, less denser and do not sink (subduct)

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10
Q

What is the oceanic plate

A

They are thinner, younger, denser and sink (subduct)

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11
Q

What are the three types of plate margin

A

Destructive/convergent
Constructive/divergent
Conservative

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12
Q

What happens at a constructive plate margin

A

At a constructive plate margin, the plates move apart (divergent). The convection currents diverge (push apart) and cause a gap to form between the plates. Magma rises up to fill the gaps created between the plates.

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13
Q

What happens at a destructive plate margin

A

At a destructive plate margin, the plates move towards each other(convergent)

The oceanic plate slides beneath the continental plate. This is where
subduction takes place.
The rocks catch against each other as the plates are not smooth surfaces. The pressure between plates builds up until the plates cannot take any more stress. They slip past each other, causing plate movement, and result of an earthquake

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14
Q

What happens at a conservative plate margin

A

At a conservative plate margin, plates move sideaways. The plates do not move smoothly and get stuck due to friction. When the pressure builds up and the plates slip, it causes an earthquake. Conservative plate margins are also called passive or transform faults

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15
Q

What is a tsunami

A

Tsunamis are huge waves that form when tectonic activity happens on seabed. They do not function like regular waves. They surge up to 30 metres high and cause devastation when hitting land

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16
Q

What does tectonic activity mean

A

It causes water to be displaced. A wave will start from where the water was displaced before moving outwards

17
Q

What is an earthquake

A

A sudden or violent movement within the Earth’s crust followed by a series of shocks. An earthquake occurs when the Earth’s plates move and causes the ground to shake

18
Q

How do they happen at constructive plate margins

A

Pressure builds up from the cracks in the plate when moving apart

19
Q

How do they happen at destructive plate margins

A

The oceanic plate gets stuck as it moves under another.

20
Q

How do they happen at conservative plate margins

A

There is friction between the plates as they aren’t smooth. This causes earthquakes

21
Q

What are the initial consequences of an earthquake

A

Crustal fracturing
Ground shaking
Tsunamis
Lanslides

22
Q

Why are large landslides affective

A

Developing countries struggle to recover from landslides due to the lack of resources and infrastructure

23
Q

What are sub marine earthquakes

A

Results in tsunamis with devastating effects

24
Q

What are consequences of ground shaking

A

Severity and duration based on the magnitude of the earthquake and distance of the epicentre

25
Q

What are consequences of crustal fracturing

A

Deep fissures in the ground are created

26
Q

What are the two aspects of an earthquake

A

Focus and epicentre

26
Q

What is the point directly above the centre of the earthquake above the earth surface

A

Epicentre

27
Q

What causes pressure to be released under ground where energy radiates out.

A

Focus

27
Q

What is a volcano

A

A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapour, and gas are or have been erupted from the earth’s crust.

28
Q

What are the five products formed during a volcanic eruption

A

Lava
Gases
Ash
Pyroclastic flow

29
Q

What gas is emitted

A

Sulfur

30
Q

What is lava

A

Lava is the magma (molten rock) above the surface of the Earth

31
Q

What is ash

A

Ash is tiny pieces of burnt rock fragments that are blown in the atmosphere at some force. The pieces fall on land and float on air causing a volcanic winter

32
Q

What is a volcanic winter

A

During a volcanic eruption, it produces lots of ash and blocks the sun. Mount Pinatubo’s 1991 eruption reduced global temperature for 3 years

33
Q

What are pyroclastic flows

A

Pyroclastic flows are currents of hot ash, lava and gas that move downhill at speeds of up to 500km during an eruption. They are impossible to outrun and reach temperatures of up to 1000 degrees Celsius and covers distances of up to 30km from the volcano

34
Q

What are shield volcanoes

A

Shield volcanoes are found at divergent/constructive plate margins or hotspots (Pacific). They aren’t mainly explosive and release basaltic lava when a volcanic eruption is in progress. Basaltic lava is a liquid that flows gradually creating a volcano with a gentle gradient (rather than steep slope). These volcanoes do not produce ash

35
Q

How do volcanoes happen at divergent plate margins

A

Tectonic plates move away from one another to produce volcanoes. Hot magma rises from the mantle at mid ocean ridges, pushing the plates apart

36
Q

How do volcanoes happen at convergent plate margins

A

Convergent boundaries known as subduction zones create volcanoes by forcing the oceanic plate under the continental plate, melting the plate and creating pressure which results in a volcano. Where oceanic plates converge with continental plates, ocean sediments are pushed underneath the continental plate

37
Q

Do conservative plate margins occur at volcanoes

A

No they don’t

Geography (6 decks)

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