1. Earthquakes

2. Fault Crack or fracture in Earth’s crust along which movement occurs
Occur at plate boundaries
Plate boundaries may have more than one fault

3. Earthquakes
Vibrations caused by the rupture and sudden movement in Earth’s crust

4. Scientists that study earthquakes
Seismologists
Scientists that study earthquakes

5. Earthquakes
Focus
Location where rocks move along a fault and seismic waves originate
Epicenter
Location on Earth’s surface directly above the earthquake’s focus

6. Earthquakes Seismic Waves
Energy that travels as vibrations on and in Earth

7. Earthquakes Types of Seismic Waves Primary (P) Waves
Longitudinal or compression waves
Fastest waves of the earthquake, arrive first at distant points
Move back and forth in the same direction the wave is traveling

8. Earthquakes Types of Seismic Waves Secondary (S) Waves
Transverse waves
Moves perpendicular to the direction the wave is moving
Travels through solid rock

9. Earthquakes Types of Seismic Waves Surface Waves
Cause particles in the ground to move up and down in a rolling motion
Travel only on Earth’s surface

11. Earthquakes Magnitude How much energy is released during an earthquake
Measured on the Richter scale 1 to 9.9