Chapter 6 Notes Types of stress: Tension – Stress that stretches and pulls rocks, happens when two plates move apart.

Chapter 6 Notes Types of stress: Compression – The stress that squeezes rocks, happens when rocks push together.

Chapter 6 Notes Types of stress: Shearing – Stress that pushes rocks in opposite direction, happens when plates slide past each other

Chapter 6 Notes Kinds of Faults: In many faults the fault line is slanted

Chapter 6 Notes Kinds of Faults: Normal Fault –occurs when tension pulls rocks apart. The hanging wall slips down.

Chapter 6 Notes Kinds of Faults: Reverse fault – When compression pushes rocks together. The hanging wall slides up and becomes higher than the footwall.

Chapter 6 Notes Kinds of Faults: Strike-Slip Fault – Occurs when shearing pushes rocks in different directions. Sections of rock slide past each other horizontally.

Chapter 6 Notes Changing Earth’s Surface: Compression of Earth’s surface causes folding Anticlines – Folds that bend upward into ridges Synclines – Folds that bend downward into valleys

Chapter 6 Notes Earthquakes and Seismic Waves: Earthquake – The shaking that occurs when rocks move inside the Earth. Focus – The place where rocks break and cause an earthquake. Epicenter – The point on the surface directly above the focus.

Chapter 6 Notes - Earthquakes

Chapter 6 Notes Types of seismic waves: P Waves – Moves rocks back and forth like a spring. Fastest waves.

Chapter 6 Notes Types of Waves: S Waves – Moves rocks up and down. Slower than P waves, but do more damage.

Chapter 6 Notes Types of waves: Surface waves – Combined P and S waves that travel along the surface. Are the slowest Do the most damage.

Chapter 6 Notes Measuring Earthquakes: Mercalli Scale – Based on the amount of damage done. Uses Roman numerals I – XII to rank the damage. (See figure 9 in book) Richter Scale – Based on the size of the seismic waves. A seismograph is used to measure seismic waves. Does not work well for large or distant earthquakes.

Chapter 6 Notes Measuring Earthquakes: Moment Magnitude Scale – Based on the amount of energy an earthquake releases. (Includes seismic wave size)

Chapter 6 Notes Monitoring Earthquakes: The Seismograph – A drum vibrates when seismic waves reach it as a suspended weight with a pen attached records the vibrations.

Chapter 6 Notes We use seismographic data to: map faults monitor changes along faults (like how much friction) try to predict earthquakes

Chapter 6 Notes Earthquake Safety: Geologists can determine earthquake risk by locating where faults are active and where past earthquakes have occurred.

Chapter 6 Notes How Earthquakes Cause Damage: Shaking – Causes landslides and avalanches. Loose soil shakes more than rock. Liquefaction – The violent shaking can turn loose soil into liquid mud. Aftershocks – Buildings weakened by the initial quake can be finished off by the aftershocks. Tsunamis – Giant waves caused by under sea earthquakes.

Chapter 6 Notes Steps to earthquake Safety: Drop, Cover, and Hold If outdoors, go to an open area and sit down on the ground If you live in an earthquake area, have an earthquake kit that includes bottled water, canned food, and other emergency supplies (Like a First-Aid Kit)

Chapter 6 Notes Designing Safer Buildings: Newer buildings are built stronger and more flexible Older buildings need to be modified and reinforced (Fiberglass wrap) Base-isolated building – Rests on shock-absorbing rubber pads to reduce the energy that reaches the building. (Like suspension on a car)

Chapter 6 Notes - Earthquakes