Tectonic plates Flashcards
Name 3 differences between oceanic and continental crusts
- Oceanic crusts are thinner
- Oceanic crusts are denser
- ## Continental crusts are lighter
Which layer of the earth is the thickest?
Mantle
Which layer of the earth is the thinnest?
Crust
What is a continental drift?
When continents gradually move across the globe over a long period of time
How do convection currents cause plates to move?
Magma in the mantle heats and rises to the crust. It cannot break through the crust so it spreads sideways, dragging the plates with it.
What happens at constructive plate margins?
Plates move away from each other due to convection currents and as they move, there is friction between the cracks, causing pressure to build and release the earthquake
What happens at destructive plate margins?
An oceanic and continental plate move towards each other and the oceanic plate sinks as it is heavier. There is friction between the plate which causes them to get stuck. Pressure builds which is released in the form of an earthquake ( if it happens under the sea it will also cause a tsunami ). The oceanic plate then sinks to the mantle and melts, causing extra magma to rise up and become a volcano.
What happens at conservative plate margins?
Plates slide past each other due to convection currents and get stuck, causing a build up in pressure which releases as an earthquake.
How do earthquakes happen?
Friction - friction between the plates, causing them to get stuck
Pressure - pressure builds up between the plates
Release - released in the form of an earthquake
What are primary impacts?
Primary impacts are impacts that happen as an immediate result of a natural disaster
Example: death, injuries, infrastructure collapsing
What are secondary impacts?
Impacts that happen as a result of primary impacts
Example: disease, homelessness, money loss
Case study:
Afghanistan
What were some primary effects?
1150 people were killed
85% of medical infratsructure damaged
Secondary effects of earthquake in Afghanistan?
25 villages destroyed from landslides
Cost $15 million
Higher risk of disease like cholera
What are the parts of the earth ( different layers )?
Crust
Mantle
Outer core
Inner core
What are some hazards from a volcano?
Pyroclastic flow - when ash columns collapse and travel at fast speeds
Ash columns - can block the sun and stop planes from flying
Volcanic bombs - when volcanic rock is thrown from the volcano
Mudflow - when water mixes with mud and can cause floods or destroy houses
