Earthquake WavesLearning Target: How does the energy from plate movement make earthquakes?

• Caused by sudden movement of rocks or a fracture in the crust (fault)

• Potential energy is stored as stress between plates or fault lines in the crust

• The released Kinetic energy creates vibrations throughout the earth- called seismic waves

• Energy travels outward in 3 directions

1) What is an earthquake?

2) Primary Waves (P waves)• can travel through solids, liquids and gases• Fastest seismic waves, first detected• Particles rock back and forth; squeezing and

stretching matter

Three Types of Seismic Waves

P Wave motion

3) Secondary Waves, S waves•Cannot travel through liquid layers of Earth• Slower than P waves, arrive later•Move side to side as they travel

S Wave motion

3) Surface Waves

A. The first is called a Love wave. it moves the ground from side to side in a horizontal plane but at right angles to the direction of motion. The horizontal shaking of Love waves is particularly damaging to the foundations of structures.

B) The second type of surface wave is known as a Rayleigh wave. Like rolling ocean waves, Rayleigh waves wave move both vertically and horizontally in a vertical plane pointed in the direction in which the waves are travelling.

5) How are waves measured?

6) How are earthquakes measured?• The size of an earthquake is determined by the

amount of energy measured by amplitude of wave OR duration of earthquake

• Magnitude is measured by Richter Scale• As numbers go up on the Richter Scale, the

energy is 10 times stronger than the lower number!

Earthquake Wave Energy:7) Energy of a wave is measured by the amplitude, the height the ground moves as the wave passes

8) What is happening to the amplitude of this wave?

9) Which magnitude would you first notice if an earthquake happened?

The path of P and S waves through Earth’s interior

10) Why don’t S waves travel through the core?

Plate boundary for Northwest

11) What type of plate boundary is between the North America Plate (land) and the Juan De Fuca Plate (ocean)?What is happening to the ocean plate?