Term 1.0 - Earthquakes etc Flashcards
(50 cards)
Constructive plate : movement
Moving apart
Destructive/convergent plate : movement
Moving together, subduction
—>
Collision plate : movement
Moving together
- —>
- —>
Conservative plate : movement
Moving alongside (in opposite directions) ----->
Constructive plate : example
Iceland
Destructive/convergent plate : example
Japan, countries in the ring of fire
Collision plate : movement : example
Mount Everest, China, Nepal
Conservative plate : example
California
Constructive plate : hazards
Shield Volcanoes
Destructive/convergent plate : hazards
Composite volcanoes, earthquakes
Collision plate : hazards
Fold mountains, earthquakes
Conservative plate : hazards
Earthquakes
Destructive plate boundaries : steps (5)
- Convection currents cause a continental and an oceanic plate to collide together.
- The oceanic crust is denser than the continental crust so is forced down the mantle. This is called SUBDUCTION.
- This jolting process creates powerful earthquakes.
- The immense friction and heat causes the oceanic crust to melt, turning it into magma.
- The extra magma causes pressure to build up and magma is forced up through the crust, creating violent composite volcanoes.
Constructive plate boundaries : steps (4)
- Convection currents cause 2 plates to move away from each other.
- This leaves a gap in the earth’s crust.
- Magma then rises up to fill the gap and creates a small, shield volcanoes.
- Magma cools and creates new land –> solidifies
What is the name of the area where the oceanic crust is forced down the mantle? - destructive
SUBDUCTION ZONE
Collision plates
Type of destructive plate boundaries but NO SUBDUCTION
Conservative plate boundaries : steps (4)
- Convection currents cause 2 plate to slide past each other.
- As they slide past each other, the immense pressure of the plates cause friction to build up.
- This friction builds up until the pressure too much and the plates jolt forward in a jerky movement.
- This rapidly releases the huge amount of pressure that had built up. This energy flows through the plates as seismic waves which cause earthquakes.
Focus - conservative plates
the actual point on earth where an earthquake happens. Different focuses have different depths.
Epicenter - conservative plates
The point on the Earth’s surface directly above the focus.
Seismic waves - conservative plates
Movement of energy in ripples through the earth, creating earthquakes.
Tectonic plate
The earth’s crust is broken into different pieces, which float on the mantle and are moving very slowly.
Each piece of the crust is called a tectonic plate.
Convection currents/cells process (7)
- The mantle (closest to the outer core) is heated.
- The heated mantle’s density is reduced and it rises.
- As it rises it moves further away from the heat source and starts to cool.
- The pressure of more rising mantle causes the current to dissipate sideways.
- As the current moves below the crust, friction drags the plates with it causing them to move.
- The mantle continues to become cooler and more dense and starts to sink.
- The process repeats in a circular motion.
Oceanic crust : key facts (3)
- Carries oceans
- Denser, thinner, younger than continental crust
- Made of basalt rocks, which are darker.
Continental crust : key facts (3)
- Carries land
- Lighter, thicker, older than oceanic crust
- Mostly made up of rocks such as granite (light coloured).
