Restless earth Flashcards
(25 cards)
What are the three plate margins called?
1) constructive plate margins
2) destructive plate margins
3) conservative plate margins
What is a plate margin (also known as a plate boundary)
a plate margin is where two tectonic plates meet.
What are the two types of tectonic plates?
1) oceanic
2) Continental
What are oceanic plates like?
Oceanic plates are denser (heavier) but thinner.
What are continental plates like?
Continental plates are less dense but thicker.
What is oceanic crust mostly made of?
Basalt
What is continental crust mostly made of?
Granite
How thick is oceanic crust?
5 - 10km (3.6miles) thick
How thick is continental crust?
30 - 50km (20-30 mile) thick
What are some similarities between oceanic crust and continental crust?
- They are both types of crust
- They are both made up a rock
- They are both solid
- They both make up tectonic plates
- They are both moving
What is a destructive plate margin?
- Two plates are moving towards each other
- One is oceanic and the other is continental.
- The denser plate (oceanic) will be abducted beneath the continental plate into the mantle.
- Friction between the two plates causes earthquakes
- As the oceanic plate is forced down into the mantle it melts the magma that is created rises up this forms a volcano.
What is a constructive plate margin?
- two plates are moving apart
- Both plates are oceanic
- as the plates separate magma is able to force its way through the gap that is created.
- I’m reaching the surface. This magma erupts informs a volcano.
What is a conservative plate margin?
- Two plates are moving alongside each other
- This could be an opposite direction or in the same direction
- Both of the plates are continental
- Friction between plates causes large earthquakes.
- No volcanoes occur as there is no Mac for reaching the surface.
What is the order for the layers of the Earth? (Starting at the centre.)
inner core — outer core — mantle — crust
Explain what is meant by continental drift?
the plates underneath are moving so is causing continent to drift.
What tectonic hazards are found in a destructive plate margin?
Volcano and earthquake
What tectonic hazards are found in a constructive plate margin?
Volcano
What tectonic hazards are found in a conservative plate margin?
Earthquake
Give two reasons why many people live in areas that are prone to tectonic hazards?
- Because it is cheaper, to live because it is a more dangerous place to live.
- Because there are a job opportunities because the jobs are more dangerous
Define a focus?
A focus is the point within the Earth’s crust where the earthquake originates and where the energy is released.
Define a epicentre?
The epicentre is the point on the Earth’s crust that is directly above the centre of the earthquake.
Define a Richter scale?
A Richter scale measures the magnitude of an earthquake.
Why are impacts of natural hazards are always worse in LICs?
Natural hazards impact LICs more because of
- weaker infrastructure,
- Less effective emergency response.
lower economic capacity to recover.
What is an example of a case study of a volcano eruption?
1980 Mount St Helens
