Earthquakes and Tsunamis Flashcards
How is an earthquake formed?
Pressure builds up and one rock gives way. Energy is released in seismic waves. These travel through the Earth, making things shake.
How can we measure earthquakes?
The richeter scale measures the magnitude of a tremor (how powerful it is) using an instrument called a seismograph.
What is the Mercalli scale?
1 - Tremors only felt by instruments
5 - People feel tremors, hanging objects swing
8 - Walls collapse, buildings damaged
9 - 12 - Buildings collapse, cracks open in ground
What are tsunamis?
A big wall of water
How are tsunamis formed?
When earthquakes measure more than 6.5 on the richeter scale
The earthquakes focus is shallow beneath the Earth’s surface
The focus is also beneath the ocean
They can also be caused by landslides
