Earthquakes and Volcanoes Flashcards
What is the theory of Plate Tectonics?
It is the theory that the earth’s crust is split up into plates and these have moved over time to where the earth’s continents are now. They have moved very slowly over the space of 5 million years
What was the evidence used to support the tectonic plate theory?
There were numerous maps that showed all of the continents drifting away over time. There was also evidence of the same fossils on South America and Africa which suggests that they were joined together previously.
What happens at a constructive divergent plate boundary?
A plume of magma rises, pushing the plates in different directions but it moves slowly. An example of this is the Mid-Atlantic Ridge. These can also create new landforms like Iceland.
What happens at a destructive subduction plate boundary?
At this plate boundary, the oceanic crust subducts into the mantle. It breaks down into the lithosphere and the asthenosphere. The oceanic crust gets pushed down because it has a much higher density than the continental crust. An example of this is the Mariana Trench. Earthquakes can happen here as well as composite volcanoes forming here.
What happens at a destructive collision plate boundary?
This is a plate boundary where two continental plates meet and collide and push up to form fold mountains. This happens because the continental plates are both as dense as each other. An example of this is the Himalayas where the continental plate that is known as India collided with the bottom of the Eurasian Plate.
What happens at a conservative plate boundary?
This is when two plates are sliding against each other, either in opposite directions or in the same direction with one of them going quicker than the other. Fault lines such as the San Andreas Fault can form here as well as earthquakes happening.
What are the effects of an earthquake?
There are four types of effects from earthquakes or any natural disaster: social, environmental, economic and political. Social effects includes destruction of homes and temporary shelter. Environmental impacts include loss of wildlife and forests, economic effects include loans back to countries who have provided aid and political effects include relief operations made by the government.
What is the epicentre of an earthquake?
The epicentre is the point directly above the focus on the Earth’s surface.
What is the focus of an earthquake?
The point within the earth where the earthquake rupture starts
What is the Richter Scale?
The Richter scale is a measure of an earthquake’s magnitude which was made by Charles F. Richter and Beno Gutenberg but it has know been replaced by the moment magnitude scale. It climbs up in a weird way because an increase of 1 on the scale shows an increase of ten times as intense shaking and an increase of 30 times as much energy released. It is a LOGARITHMIC SCALE.
What are the positives of living next to a volcano?
- There is lots of fertile soil which contains potassium, nitrogen and sulphur.
- There are lots of minerals that can be found near volcanoes such as gold, silver, diamonds, copper and zinc.
- There are opportunities to earn money from tourism around volcanoes e.g. Iceland
- Research takes place at volcanoes. Someone who studies a volcano is known as a volcanologist.
- People can use geothermal energy. It is a renewable source of energy that is the thermal energy generated and stored in the Earth.
What are the disadvantages to living next to a volcano?
- Air quality declines.
- You can die because of an eruption☠
- It damages farmland and is destructive to infrastructure.
What is an active volcano?
A volcano that has a recent history of eruptions and they are likely to erupt again.
What is a dormant volcano?
A volcano that has not erupted for a very long time but may erupt at a future time.
What is an extinct volcano?
A volcano that is not expected to erupt again in the future.
