1. Chapter 9 Earthquakes

2. Forces inside Earth
Elastic Limit – point at which rocks will remain bent or break, due to applied stresses.
Faults – surfaces along which rocks break and move in different directions relative to the fault surface.
Earthquake – the movement of the ground, caused by waves from energy released as rocks move along faults.

3. Types of Faults Normal Fault Reverse Fault Strike-Slip Fault
Plates move apart; Tension
Plates crash into each other; Compression
Rocks move past each other; Shearing
Ex. Mid Ocean Ridge
Ex. Rocky Mountains
Ex. San Andreas Fault
Aka Divergent Boundary
Aka Convergent Boundary
Aka Transform Fault Boundary

4. Earthquake Information
Focus – the point in Earth’s interior where earthquake energy is released.
Epicenter – the point on Earth’s surface directly above an earthquake’s focus.

5. Seismic Waves
These are the waves of energy that move outward from the earthquake’s focus and make the ground shake
Primary Waves – travel through the Earth by causing particles in rocks to compress and stretch apart (back and forth) in the direction of the wave. FASTEST WAVES
Secondary Waves - travel through the Earth by causing particles in rocks to move at right angles to the direction of the wave.

6. Primary Waves – travel through the Earth by causing particles in rocks to compress and stretch apart (back and forth) in the direction of the wave. (FASTEST WAVES)
Secondary Waves - travel through the Earth by causing particles in rocks to move at right angles to the direction of the wave.

7. Surface Waves
These waves are emitted from the epicenter of an earthquake. Give particles an elliptical and back/forth motion.
These cause buildings to collapse. These waves cause the most destruction. (SLOWEST WAVES)