The Restless Earth: Earthquake - Cause and Measurement Flashcards
Name the 3 plate boundaries?
Destructive.
Constructive.
Conservative.
Earthquakes are caused by what?
Tension that builds up at the plate boundaries.
How does tension build up at a destructive plate boundary’s?
When one plate gets stuck as it’s moving down past the other into the mantle.
How does tension build up at a constructive plate boundary’s?
Along cracks within the plates as they move away from each other.
How does tension build up at conservative plate boundary’s?
When plates that are grinding past each other get stuck.
The plates eventually jerk past each other sending
Shock waves(vibrations).
What are the vibrations?
The earthquake.
Shock waves spread out from where?
The focus.
What is the focus?
The point in the earth where the earthquake starts .
What happens near the focus?
Waves are stronger and cause more damage.
What is the epicentre?
The point on the Earth’s surface straight above the focus.
Weak earthquakes happen…
Often.
Strong earthquakes happen…
Rarely.
Earthquakes can be…
Measured.
Name the 2 ways earthquakes can be measured?
The richter scale.
The mercalli scale.
What does the richter scale measure?
Amount of energy released by the earthquake.
What is the magnitude?
Measurement of the amount of energy released.
What is magnitude measured using?
Seismometer.
What is a seismometer?
A machine with an arm that moves with vibrations of the earth.
What doesn’t a Richter scale have?
An upper limit.
The Richter scale is…
Logarithmic.
What does logarithmic mean?
Earthquake with a magnitude of 5 is ten times more powerful than one with a magnitude of 4.
Most people don’t feel earthquakes of a magnitude of…
1-2.
Major earthquakes are above 5.
What does the mercalli scale measure?
Effects of an earthquake.
How are the effects measured?
Asking eye witnesses for observations of what happened.
Words or photos.
What does the mercalli scale range from?
1 to 12.
On the mercalli scale what happens at 5?
Felt by everyone.
Objects moved.
On the mercalli scale what happens at 12?
Total destruction.
On the mercalli scale what happens at 1?
Only detected by instruments.
