Tectonics Flashcards
Oceanic crust
Heavier and denser
Sinks - continuously destroyed
Tectonics distribution - on boundaries
Earthquakes: destructive
Volcanoes: destructive + constructive
Unpredictable motion
Fold Mts: destructive
Move together, squeeze + raise sea beds
Constructive
Oceanic
Magma fills gap, new crust, sea floor spreading
Gentle earthquake
Shield volcano
MID ATLANTIC RIDGE
Conservative
Slide past at different speeds, pressure builds, jerks
Violent earthquake
No volcano
SAN ANDREAS FAULT
Destructive
Oceanic under continental
Friction/heating, magma, pressure, rises up lines of weakness
Lava solidifies - volcano
Violent earthquake (forced down)
ANDES MTS RANGE
Convection currents
Intense heat pushes plates, causing them to move/float
Fold mountains
Mountains from uplifted crust
Same type towards
Crust crumples into folds, uplifted
Edge of continent (thickest)
Earthquake
Sudden movement in crust
Plates move (convection currents/heat), jam, pressure builds until friction overcome, one jerks past
Focus
Actual point of earthquake underground
Epicentre
Where vibrations are greatest
Impacts of earthquakes
Death/injury
Homes and transport - no aid
Water contaminated
Gas pipe fires - woodland/landslide
Disease spreads
Refugee and rebuild costs
No income (land)
Habitats
Why live near earthquake?
Poverty (forced)
Overpopulation
Unwilling to move
Buildings improved
Economic resources/near sea
Continental crust
Older
Lighter
Can’t sink - permanent, strong
CS Kobe earthquake Osaka Bay, East Asia - Jan 1995
7.2 Richter scale
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
Reducing earthquake impacts
Prepare emergency services Practice drills - 1st September Few storeys building Automatic window shutters Fire resistant Steel frames sway
Volcano and types
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
Hazards and reducing risks of volcano
Lava flows + bombs
Ash clouds
Pyroclastic flows
Lahars (mudslides)
Reinforced sloping roofs - no ash settles
Emergency services
Monitoring history
CS Chaiten volcano - 2 May 2008
Composite
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
Why live near volcano?
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
