Restless Earth Flashcards
Why do plates move?
Heat is released from the core which creates convection currents in the mantle. The plates move as a result of this.
What is a conservative plate margin?
A conservative plate margin is where the plates move in the opposite direction to one another, or the same direction at different speeds.
What is a destructive plate margin?
A destructive plate margin is where the plates push towards one another. While this happens, one is less dense than the other.
The oceanic plate is more dense, and goes underneath and this is called subduction.
What is a constructive plate margin?
A constructive plate margin is where both plates are pushing away from one another.
Magma rises up, forcing the crust apart. Activity happens in the Atlantic Ocean and Mid Atlantic Ridge.
Where are composite volcanoes and shield volcanoes formed?
They are formed at constructive plate boundaries.
Describe is the lava formed from a composite volcano.
The lava is sticky so it does not flow far, this is why the sides are steep. The lava is also acidic.
Describe the lava formed from a shield volcano.
The lava is sticky, so it flows a very long way.
Using the Moneserrat case study: give some of the social and economic impacts.
Firstly, the USA sent troops for evacuation, which helped get all of the people out. Secondly, charities also sent emergency food for farm animals, as most of the food would have been destroyed by the lava the volcano produced. Thirdly, some people evacuated on boats paid for by thee government in the United Kingdom and the United States of America. Additionally, the UK government sent £17 million of emergency aid, including temporary buildings and water purification systems.
What is the difference between a super volcano and a normal volcano?
A volcano is a small volcano, whereas a super volcano is larger and has much more of a negative impact.
What is meant by the term ‘caldera’?
A caldera is when a super volcano erupts and then sinks down, very close to the ground, because there is no magma to support it.
What will the impacts be of a super volcano?
All life up to 100km away would be killed by falling ash.
Erupted magma would be flung 50km into the atmosphere.
After an eruption, a super volcano sinks down, because there is no magma to support it, then it bulges up and then the pressure rises and then a super eruption takes place.
Give one predicted affect of a super volcanic eruption.
There will be world wide problems, as the ash from the eruption would block out the rays of the sun which would cause long winters and travel disruption on a global scale.
What type of volcano is formed when the lava is runny?
A shield volcano.
What is an ocean trench?
An ocean trench is a long, narrow, deep depression in the ocean bed, typically one running parallel to a plate boundary and marking a subduction zone.
How are fold mountains formed?
Fold mountains form along both Destructive and Collision plate boundaries. They form when two plates with landmasses on them move towards one another. The plates push accumulated sediment in the sea into folds between them.
