Earthquakes and Plate Tectonics Flashcards
Give one example of a destructive plate boundary
Where the Nazca Plate meets the South American Plate.
In which direction do plates move at a destructive boundary?
They move together. One plate may sink (subduct beneath the other) or the plates may collide causing fold mountains.
What is a secondary effect?
Impacts that occur as a result of the primary effects.
What are tectonic plates?
The Earth’s crust is broken into 7 major pieces which ‘float’ on the magma in the mantle. These are known as the tectonic plates.
Where do volcanoes and earthquakes usually occur?
Along the lines of the plate boundaries.
The Richter scale uses a logarithmic scale. What is this?
This is when each whole number increase in magnitude represents a 10 times increase in amplitude. As an estimate, each whole number step in magnitude means the release of about 31 times more energy. So a 6.1 magnitude earthquake is 10 times more powerful than a 5.1.
Boundaries or boundarys?
Boundaries
Is it enough to say that “one primary effect of an earthquake is buildings collapsing” in the exam?
No. Try to use specific details from a case study. E.g. “In Ecuador 2006 pyroclastic flows destroyed 7 villages on the north western slopes of the Tungurahua Volcano”.
What causes tectonic plates to move?
Convection currents in the mantle cause the plates to move around 2-5cm per year (about the rate your fingernails grow).
Which instrument measures the force of an earthquake?
A Seismometer
Ricter Scale or Richter Scale?
Richter Scale
What are the names of the three types of plate boundary?
Constructive, destructive and conservative plate boundaries.
Earthquakes can be accurately predicted. True or false?
False. We cannot confidently say where or when an earthquake will strike or how strong it will be.
What are the names of the four layers of the Earth?
Inner core, outer core, mantle and the crust.
Give one example of a conservative plate boundary
Where the North American plate and the Pacific Plate slide past each other along the West coast of the USA.
What is a primary effect?
Impacts as a direct result of the event itself.
Gas pipes breaking is a primary effect of an earthquake. True or false?
True. As the earth violently shifts pipes can break. This can lead to a secondary effect such as fires.
Which of the Earth’s layers is the thinnest?
The crust. Contnental crust is around 20 miles (35km) thick. Oceanic crust is newer and more dense although it is thiner at around 6 miles (10km) thick.
What is a tsunami?
A large ocean wave caused by an underwater earthquake.
In which direction do plates move at a constructive boundary?
They move apart. This can cause wide volcanoes and ocean ridges.
Give an alternative to the Richter scale.
The Mercalli scale. This measures how much damage the earthquake caused on the surface rather than how much the Earth has moved.
What are convection currents?
The Earth’s core heats magma in the mantle which rises. Eventually it moves sideways dragging the crust with it then falls back down towards the core as it cools. This process repeats in a cycle known as a convection current.
What are foreshocks?
Smaller ground tremors (shaking) occuring before the main earthquake.
Give one example of a constructive plate boundary
Where the Eurasian Plate moves away from the North American plate. This creates the Mid-Altlantic Ridge.
Unemployment is a primary effect of a volcano. True or false?
False. Unemployment is a secondary effect caused by the primary effect of businesses being destroyed.
What is magma?
Hot, molten and liquid rock beneath the surface of the Earth. Often called lava when it reaches the surface.
In which direction do plates move at a conservative boundary?
They move alongside each other either in the same direction or opposite directions. This can cause powerful earthquakes.
What are aftershocks?
Smaller ground tremors (shaking) occuring after an earthquake.
What is the Richter Scale used for?
To measure how intense (how much shaking) the earthquake was.
