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GCSE Geography > The restless earth > Flashcards

The restless earth Flashcards

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1
Q

What are the four layers of the earth?

A

Inner core, outer core, mantle, lithosphere/crust

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2
Q

What is the crust/lithosphere divided into?

A

Tectonic plates

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3
Q

Why do the tectonic plates move?

A

Due to convection currents in the mantle they float on

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4
Q

What is a constructive plate margin?

A

Where two tectonic plates are moving apart; causing cracks in the crust where a gap is forming; magma rises up into cracks to form new crust

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5
Q

What hazards are found at constructive plate margins?

A

Volcanoes and earthquakes

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6
Q

What is a destructive-subductive plate margin?

A

Where and oceanic plate is forced underneath a continental plate; the oceanic plate is destroyed as is it melts to form magma

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7
Q

What hazards are found at destructive-subductive plate margins?

A

Volcanoes and earthquakes

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8
Q

What is a destructive-collision plate margin?

A

Where two continental plates move towards each other and collide.

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9
Q

What hazards occur at destructive-collision plate boundaries?

A

Earthquakes

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10
Q

What is a conservative plate margin?

A

Where two plates slide past each other; they move at different angles and speeds- causing sticking

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11
Q

What hazards occur at conservative plate margins?

A

Earthquakes

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12
Q

What are the characteristics of oceanic crust?

A

Newer (most less than 200 million years old) , thinner (5-10 km thick), denser (more basalt in it), can sink, can be renewed and destroyed

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13
Q

What are the characteristics of continental crust?

A

Older (most over 1500 mil yrs old), thicker (20-70 km), less dense (more granite in it), cannot sink, cannot be renewed or destroyed

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14
Q

What is the difference between the focus and the epicentre?

A

The focus: where the pressure build up has occurred (underground) between the plates
The epicentre: point on the crust directly above the focus, from which seismic waves radiate out

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15
Q

What is a seismograph?

A

The machine that measures the size/magnitude of the waves

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16
Q

When did the Haiti earthquake occur?

A

12th January 2010

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17
Q

What % of people in Haiti live in poverty and what % have access to clean water? (pre-earthquake)

A

80% of Haitian people lie in poverty

46% have access to clean water (not even half)

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18
Q

Where is Haiti?

A

An island in the Caribbean, (half of the island is the Dominican republic); it is found in the South American continent

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19
Q

What is the average life expectancy in Haiti? how many people per doctor?

A

Average life expectancy: 62 yrs old (1/2 pop. under 18)

People per doctor: 1000 people per 0.25 doctors

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20
Q

Where was the epicentre and focus of the Haiti earthquake?

A

Epicentre: 25 km from Haitian capital Port-au-Prince
Focus: only 13 km underground

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21
Q

What were 4 direct impacts of the earthquake in Haiti?

A

34/37 of doctors in Port-au-prince were killed, 1/3 buildings destroyed, 300,000 people left homeless, 230,000 (approx.) killed directly

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22
Q

What were 4 indirect impacts of the earthquake in Haiti?

A

5 years later people still living in tents in capital, Nov. 2010 cholera outbreaks, over 300,000 killed by cholera, only 2% of $1 million relief funds raised for Haiti released, Haitian tourism decline

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23
Q

What were 3 short term responses of the Haiti earthquake?

A

3/4 damaged buildings inspected and repaired, 200,000 received food or cash for public work (e.g. clearing rubble), 2000+ helped by Dominican republic emergency team

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24
Q

What were 2 long term responses of the Haiti earthquake?

A

World bank pledged $100 mil to support reconstruction/recovery programmes, red cross & UN remained in Haiti to help- stayed for 2 yrs & built long term shelters

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25
When did the Japan earthquake begin?
11th March 2011
26
What was the rating of the Japan earthquake?
The earthquake was a 9 on the Richter scale
27
How strong was the Japan earthquake?
It was the force of 2 million Hiroshima bombings happening simultaneously
28
Where was the focus of the Japan earthquake?
Only 30 km underground
29
Where was the epicentre of the Japan earthquake?
130 km away from the city of Sendai
30
What physically happened to Japan as a country when the earthquake struck?
The whole of Japan shifted 3 m out to sea, and parts of the coast sunk over 1 m
31
What were 4 direct impacts of the Japan earthquake?
Gas and oil lines ruptured- causing fires, liquification, 350 km away in Tokyo buildings shook for 5 minutes, railways buckled (transport impossible)
32
What were 3 secondary impacts of the Japan earthquake?
Tsunami, Fukishima nuclear power plant flooded, over 500 aftershocks (over 7 exceeded 7.2 on Richter scale)
33
How many people were killed by the Japan tsunami?
19,000 to 20,000 people
34
How fast was the Japan tsunami travelling?
800 km/h with a 100 km wavelength
35
What kind of plate boundary is Japan on?
A stick-slip fault boundary
36
What are the steps to attempt to reduce the impacts of earthquakes?
Protect, prepare, predict
37
What does the 'protect' stand for (in terms of earthquake impact reduction)?
Constructing buildings so they are safe to live in and will not collapse
38
What does the 'prepare' stand for (in terms of earthquake impact reduction)?
Organising activities/drills so that people know what to do if an earthquake happens
39
What does the 'predict' stand for (in terms of earthquake impact reduction)?
Attempts to forecast an event- where it will happen- bases on current knowledge
40
Where are ocean trenches formed?
On destructive-subductive plate boundaries
41
Where are fold mountains formed?
On destructive-subductive and destructive-collision boundaries
42
How are fold mountains formed?
Geosyncline (depression between plates)under sea, fills with sediment from rivers, sediment compressed to rock, plates move together-sediment folds
43
What are 3 reasons that people live close to volcanoes?
The soil is fertile from ash and lava, they are tourist attractions, they are a source of geothermal energy
44
Where are the world's most active volcanoes found?
At the edge of plate margins- specifically the 'pacific ring of fire'
45
What are the two main types of volcano?
Composite and shield volcanoes
46
What are the characteristics of shield volcanoes?
Gentle sloping sides, usually non-violent, caused by eruptions of 'basic lava'
47
What are the characteristics of composite volcanoes?
Steep-sided, symmetrical, narrow base, acid lava, lava cools quickly, often explosive eruptions
48
Why do composite volcanoes have explosive eruptions?
Lave cools quickly, so can plug the vent, causing pressure build-up and explosive eruptions (more pressure is released)
49
Where are composite volcanoes usually formed?
Destructive subductive plate boundaries
50
Where are shield volcanoes usually formed?
Constructive plate boundaries
51
How are volcanoes formed at destructive-subductive boundaries?
Oceanic plate subducts, part of oceanic melts into magma, heat/pressure in mantle forces magma along cracks in earth's crust, magma erupts at surface (volcano), layers of ash/lava heightens volcano over time
52
How are shield volcanoes formed at constructive plate boundaries?
Plates move apart, magma rises up to plug gap (new rock), some magma may be forced along a crack/vent + erupt at surface, a submarine volcano is formed, volcano grows higher after constant eruptions
53
What is a natural hazard?
An event over which people have no control, but threatens people's lives/possessions,
54
What are 4 methods used to monitor volcanoes?
Measuring earthquakes (using seismographs), tiltmeters, digital time lapse cameras, GPS
55
When did the eruption of Eyjafjallajokull occur?
It continuously erupted from late March 2010-October 2010
56
When was the ash cloud (of Eyjafjallajokull) released?
14th April 2010
57
Where is the volcano (Eyjafjallajokull) located?
Southern Iceland
58
What was the main local impact of the Eyjafjallajokull eruption?
Primary: Heavy ash fell close to volcano Secondary: flooding due to melted glacier that was on top of volcano
59
What were the local responses to the Eyjafjallajokull eruption?
People had to evacuate, livestock put inside, rescuers wore face masks to prevent choking on dense ash, people breached embankments to protect bridges from flood water
60
What were the global impacts of the Eyjafjallajokull eruption?
ash cloud caused an 8 day flight ban where around 107,000 flights were cancelled, Kenya affected (20% economy from perishable goods) so over 50,000 farmers unemployed-their goods not sold
61
What were the positive impacts of the Eyjafjallajokull eruption?
Icelandic tourist attraction and tourist centre, good crops (from nutrient rich ash), valuable materials are often found in volcanic regions
62
What are signals of a volcanic eruption?
Swelling of the magma chamber (and base of volcano) and higher concentration of gases emitted from volcano (such as sulphur dioxide)
63
What are the characteristics of a supervolcano?
larger scale, emit at least 1000 km3 of material (when erupting), have a large caldera
64
What is a caldera?
a large depression
65
How are calderas formed?
Rising magma can't escape, crust bulges, crust cracks, gas/ash escapes, magma chamber collapses forming caldera
66
Where is the Yellowstone supervolcano?
North America
67
How would population be threatened by a Yellowstone eruption?
Entire N. American population would be damaged, but an ash cloud of that size could threaten world population
68
How big is the magma chamber of the Yellowstone supervolcano?
It's thought to be 80 km long, 40 km wide and 8 km deep
69
What would be the direct impacts of a supervolcanic eruption?
All life up to 1000 km away destroyed by lava/falling ash/force of explosion, 1000 km3 lava, amount of ash and gas would block most of the sun's rays
70
What would be the secondary impacts of a supervolcanic eruption?
Harsh winter across Earth (little sun), starvation (no crops), economic collapse
71
When and where was the last supervolcanic eruption?
Toba, Indonesia, 74,000 years ago -caused a 6 year volcanic winter
72
When was the last eruption at Yellowstone?
640,000 years ago
73
How much lava would be created by a Yellowstone eruption?
1000 km3 ; enough to cover the whole of North America in a layer 12.5 cm thick

GCSE Geography (6 decks)

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