1. EARTHQUAKES
Chapter 16 pg. 426

2. OBJECTIVES Explain where earthquakes take place.
Explain what causes earthquakes.
Identify 3 different types of fault that occur at plate boundaries.
Describe how energy from earthquakes travel through the Earth.

3. What are Earthquakes? Something that causes the Earth to shake.
Seismology – the study of earthquakes.
Seismologist – a person who studies earthquakes.

4. Where do Earthquakes happen?
Near the edges of tectonic plates.
Tectonic plates are like big puzzle pieces made out of the outer most layer of the Earth.

5. What causes Earthquakes?
Tectonic plates push, pull, or slip past each other, which causes
Deformation – the bending, tilting, and breaking or the Earth’s crust; the change in the shape of rock in response to stress.
1. Plastic deformation – does NOT lead to earthquakes.
2. Elastic deformation – causes earthquakes because the rock stretches and it eventually breaks. (think of a rubber band)

6. Elastic Rebound
Elastic rebound – the sudden return of elastically deformed rock to its undeformed shape.
Think or a rubber band that has been stretched to far. Once it breaks, the pieces return to their original shape. But, the breaking of the rubber band releases energy.
The breaking of the rock releases energy in the form of seismic waves, which causes Earthquakes.

7. Faults at Tectonic Plate Boundaries
Each tectonic plate boundary has a specific motion.
PLATE MOTION
MAJOR FAULT TYPE
Transform
Strike- slip fault
Convergent
Reverse fault
Divergent
Normal fault

8. Plate motion and fault types
Transform motion – occurs where two plates slide past each other. This creates strike-slip faults.
Convergent motion – occurs where two plates push together. This creates convergent faults.
Divergent motion – occurs where two plates pull away from each other. This creates divergent faults.

9. Earthquake Zones
These are places where a large number of Earthquakes happen.
Earthquakes c an happen both near the surface of the earth or far below the earth’s surface.
Sometimes, earthquakes happen along faults in the middle of tectonic plates.

10. How do Earthquake waves travel?
Seismic waves – a wave of energy that travels through the Earth, away from an earthquake in all directions.
Body waves – seismic waves that travel through the inside of the Earth.
Surface waves – seismic waves that travel along the Earth’s surface. (Travel slowly and are very destructive).

11. PRESSURE WAVES (body wave)
Also called P waves.
P waves – a seismic wave that causes particles of rock to move in a back-and- forth direction.
They travel the fastest.
Also called Primary waves because they are the first wave detected in an earthquake.
Can travel through solid, liquid, and gas.

12. Secondary Waves (body wave)
Also called Shear waves
S waves – a seismic wave that causes particles of rock to move in a side-to-side direction.
They are the second fastest waves.
Only travel through the liquid part of the Earth.