Tectonics

Question 1

Oceanic crust

Answer 1

Heavier and denser

Sinks - continuously destroyed

Question 2

Tectonics distribution - on boundaries

Answer 2

Earthquakes: destructive

Volcanoes: destructive + constructive
Unpredictable motion

Fold Mts: destructive
Move together, squeeze + raise sea beds

Question 3

Constructive

Answer 3

Oceanic
Magma fills gap, new crust, sea floor spreading
Gentle earthquake
Shield volcano

MID ATLANTIC RIDGE

Question 4

Conservative

Answer 4

Slide past at different speeds, pressure builds, jerks
Violent earthquake
No volcano

SAN ANDREAS FAULT

Question 5

Destructive

Answer 5

Oceanic under continental
Friction/heating, magma, pressure, rises up lines of weakness
Lava solidifies - volcano
Violent earthquake (forced down)

ANDES MTS RANGE

Question 6

Convection currents

Answer 6

Intense heat pushes plates, causing them to move/float

Question 7

Fold mountains

Answer 7

Mountains from uplifted crust

Same type towards
Crust crumples into folds, uplifted
Edge of continent (thickest)

Question 8

Earthquake

Answer 8

Sudden movement in crust

Plates move (convection currents/heat), jam, pressure builds until friction overcome, one jerks past

Question 9

Focus

Answer 9

Actual point of earthquake underground

Question 10

Epicentre

Answer 10

Where vibrations are greatest

Question 11

Impacts of earthquakes

Answer 11

Death/injury
Homes and transport - no aid
Water contaminated
Gas pipe fires - woodland/landslide

Disease spreads
Refugee and rebuild costs
No income (land)
Habitats

Question 12

Why live near earthquake?

Answer 12

Poverty (forced)
Overpopulation

Unwilling to move
Buildings improved
Economic resources/near sea

Question 13

Continental crust

Answer 13

Older
Lighter
Can’t sink - permanent, strong

Question 14

CS Kobe earthquake Osaka Bay, East Asia - Jan 1995

7.2 Richter scale

Answer 14

Destructive, converging
Pacific NW subducts under Eurasian SW, slide, friction, plates jerk + release energy

200 000 buildings collapsed 
35 000 injured - 5 500 killed 
Water disrupted 
Fires 
Services - hospitals, roads - slow aid 

316 000 homeless
Airports
Electricity - no jobs

Evacuated, moved, jobs in construction

Question 15

Reducing earthquake impacts

Answer 15

Prepare emergency services 
Practice drills - 1st September 
Few storeys building 
Automatic window shutters 
Fire resistant 
Steel frames sway

Question 16

Volcano and types

Answer 16

Vent in earth’s surface where magma/gas escapes

Composite cone:
Acidic lava, narrow base, steep, vents, ash/solidified lava layers, viscous, high

Shield:
Constructive (gap), wide base, short, gentle, travels far, shallow

Question 17

Hazards and reducing risks of volcano

Answer 17

Lava flows + bombs
Ash clouds
Pyroclastic flows
Lahars (mudslides)

Reinforced sloping roofs - no ash settles
Emergency services
Monitoring history

Question 18

CS Chaiten volcano - 2 May 2008

Composite

Answer 18

Composite, dormant
Nazca E subducts under South American W, pressure, melts (magma), cracks/weakness, erupts, cools + solidifies

15km ash cloud 
Pyroclastic flows 
Lahars - Rio Blanco valley 
4500 evacuated 
1 death 
Sulphur contaminates water 
Skin/eyes irritated (ash) 
10km2 forest flattened 
Land for livestock - ill/die - less income 
Airports Chile, Argentina, Uruguay canceled 
Homeless 
2011 no water/electricity

Question 19

Why live near volcano?

Answer 19

Iceland - 300 000 people 
Geothermal energy - cheap, sustainable 
Tourism - waterfalls, Blue Lagoon - jobs 
Pumice extracted (building) 
Fertile soil 
North Altantic fish stocks - jobs 
Regular evacuation drills + monitoring