Global Hazards Flashcards
What is a destructive plate margin? For an oceanic and continental plate
- An oceanic and continental plate move toward each other
- The oceanic plate is forced beneath (subduction)
- The plate sinks forming magma
- Magma escapes through a composite volcano
What is a destructive plate margin? For two continental plates (collision margin)
- The two continental plates move towards each other
- Neither can sink so the land buckles
- This forms fold mountains
- This is a collision margin earthquakes can occur here
What is a constructive plate margin?
- The plates move away from each other
- Magma rises up to form a shield volcano
- The movement of plates over the mantle can cause earthquakes
What is a conservative plate margin?
- The plates move side by side at different speeds
- Friction occurs causing the plates to become stuck
- Pressure builds up as the plates try to move
- When released it sends out large amounts of energy causing an earthquake
What are the atmospheric circulation cells in order from equator to poles
Hadley
Ferrell
Polar
What does temperate climate experience
- air rises frequent rainfall
What does a polar climate experience
Cold air sinking, icy
What does a desert climate experience
Dry air sinking, high temps
What’s high pressure
- cold air sinking, clear conditions
What is low pressure
- hot moist air rising, stormy weather
What are two examples of extreme weather
- high wind due to mountains
- high temps along the equators
What’s the location of droughts
- anywhere but mainly located around tropics of cancer and Capricorn
What happens during an El Niño year
- warm water pushed east by trade winds
- low pressure, warm air rises causing floods in South America
- high pressure, cool air sinking causing drought in Australia
What happens during a La Niña year
-pool of warm water pushed west
- high pressure, cool sinking air causes drought in South America
-low pressure, warm rising air causing flooding is Australia
Where are tropical storms mainly located
-the tropics of cancer and Capricorn
How do tropical storms form
- 27° water, low pressure causes thunderstorm, sucks in trade winds
- Coriolis effect causing the spin
- begins to spin faster than 74 mph
- in the eye cool air sinks causing clear conditions
- loses energy source once it hits land
What’s the structure of the earth
Crust- large tectonic plates
Mantle- liquid rock moving the plates
Inner/outer cores
How do convection currents move the plates
-Liquid magma heats up becoming less dense and rises
-along the top magma cools starting to sink
-convection currents
-creates drag causing tectonic plates to move
What’s a shield volcano
Gently sloping
Found at hotspots and constructive margins
Gentle eruptions
What’s a composite volcano
Layers of ash and lava
Found at destructive margins
Violent eruptions
What’s a hotspot
Magma rises breaking through the surface
Active volcanoes can occur here
How are earthquakes caused
Plates become locked, friction, once plates move energy released as seismic waves
What’s a shallow focus earthquake
- seismic waves spread and damage large areas but are small
What’s a deep focus earthquake
- occur in destructive margins
-localised damage as seismic waves travel vertically
What are ways to mitigate a tectonic hazard
Monitoring- seismometers to detect, evacuate
Preparation- good communication systems, locate, help
Building design- shatterproof windows, don’t hurt people
