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Flashcards in Restless Earth Deck (32)
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1
Q

Describe continental crust

A

Think but less dense

2
Q

How many major tectonic plates are there

A

Seven

3
Q

How do destructive plate margins move

A

Towards each other

4
Q

In detail what happens when the two plates move towards each other at a destructive margin

A

The lighter continental crust stays above but the oceanic crust goes underneath this is called a subduction zone

5
Q

What does the rising magma cause at destructive plate boundaries

A

Composite volcanoes

6
Q

Name the three land features of a destructive plate boundry

A

Fold mountains
Ocean trenches
Composite volcanoes

7
Q

Why do earthquakes occur at destructive plate boundrys

A

Because energy build up in the subduction zone which forms and earth quake when the palates suddenly jolt under the pressure

8
Q

How do constructive plate boundrys move

A

Away from each other

9
Q

What fills up the gap at a constructive plate boundry

A

Magma

10
Q

Where are constructive margins often found

A

Under the sea

11
Q

What is formed at a constructive margin

A

Shield volcanoes

12
Q

Why are islands sometimes formed at constructive margins

A

Because the shield volcanoe produces magma which solidifies above the water

13
Q

What is the name for the margin in which the plates move across from each other

A

Conservative margins

14
Q

What occurs at conservative margins

A

Earthquakes

15
Q

What is the depression in which sediment forms to start the formation of a fold mountain

A

A geosyncline

16
Q

What happens to the sediment in a geosyncline over time?

A

It turns to rock

17
Q

What happens when pressure for plate movement is put onto the rock inside a geosyncline

A

It is forced upwards

18
Q

What is the name for the tops of a fold mountain

A

Anticline

19
Q

What are the dips of a fold mountain called

A

A syncline

20
Q

Name the features of a shield volcano

5

A
Only made of lava
Gentle slopes
Wide base 
Regular eruptions 
Runny lava
21
Q

Name the features of a composite volcanoe (5)

A
Made from ash and lava
Steep slopes
Shorter based
Irregular eruptions
Viscous lava
22
Q

Where do earthquakes happen

A

At all margins

23
Q

What is the focus

A

The underground centre of the earthquake

24
Q

What is the epicentre of an earthquake

A

The point on the surface directly above the focus

25
Q

What are shock waves

A

Waves of energy that move out in all directions from the focus

26
Q

Describe the Richter scale with four points

A

Measured magnitude
Uses sismographs
They are logarithmic
Measure 1-10

27
Q

Describe the mecaralli scale in three points

A

Measured by impact on people
Measured by human judgement
Measured in Roman numerals

28
Q

Name three physical things that make an earthquake worse

A

Magnitude
Shallow focus
Ground eg sand is worse as it shakes more

29
Q

Name four human factors that increase an earthquakes severity

A

Population density
Residential area
Self built housing
Lack of response

30
Q

What could tsunamis be described as

A

The secondary effect of a earthquake at sea

31
Q

How do tsunamis happen

A

One plate is stick under another causing tension
An earthquake occurs forcing the plate upwards
Sea rises causing water to be displaced and is pushed in a direction perhaps towards land

32
Q

Describe oceanic crust

A

Thin but dense