Earthquakes 7.1 Earthquakes occur along faults. 7.2 CHAPTER NEW CHAPTER Earthquakes the BIG idea Earthquakes release stress that has built up in rocks. 7.1 Earthquakes occur along faults. 7.2 Earthquakes release energy. 7.3 Earthquake damage can be reduced. CHAPTER OUTLINE CHAPTER RESOURCES

Earthquakes occur along faults. 7.1 Earthquakes occur along faults. Normal faults form as rocks are pulled apart. fault stress earthquake CHAPTER RESOURCES SECTION OUTLINE

Earthquakes occur along faults. 7.1 Earthquakes occur along faults. Normal faults form as rocks are pulled apart. Reverse faults form as rocks are pushed together like the Aleutian Trench and is the type of fault that causes the earthquakes in this area. fault stress earthquake CHAPTER RESOURCES SECTION OUTLINE

Earthquakes occur along faults. 7.1 Earthquakes occur along faults. Normal faults form as rocks are pulled apart. Reverse faults form as rocks are pushed together. fault Strike-slip faults form as rocks are pushed horizontally in opposite directions. stress earthquake VISUALIZATION Explore animations showing fault motion. CLASSZONE.COM CHAPTER RESOURCES SECTION OUTLINE

Earthquakes release energy. 7.2 Earthquakes release energy. focus epicenter seismic wave focus epicenter seismograph Seismic waves move out from the focus in all directions. VISUALIZATION Explore primary-wave and secondary-wave motion. CLASSZONE.COM CHAPTER RESOURCES SECTION OUTLINE

Earthquakes release energy. 7.2 Earthquakes release energy. seismic wave focus epicenter seismograph CHAPTER RESOURCES SECTION OUTLINE

Earthquake damage can be reduced. 7.3 Earthquake damage can be reduced. A powerful earthquake releases more energy and causes more shaking of the ground than does a weak earthquake. Both the Richter scale and the moment magnitude scale are often shown with a top value of 10, but neither actually has a maximum value. aftershock liquefaction Magnitude 0–3.9 Very Minor to Minor 4.0–4.9 Light 5.0–5.9 Moderate 6.0–6.9 Strong 7.0–7.9 Major Effects Near Epicenter 8.0 and above Great major to total destruction rarely noticed slight damage some structures damaged major damage to structures some well-built structures destroyed tsunami CHAPTER RESOURCES SECTION OUTLINE

Earthquake damage can be reduced. 7.3 Earthquake damage can be reduced. aftershock An area’s risk of earthquakes can be predicted. The strength of an earthquake depends in part on the distance over which blocks of rock move. 0 200 400 kilometers 0 200 400 miles liquefaction tsunami CHAPTER RESOURCES SECTION OUTLINE

Earthquake damage can be reduced. 7.3 Earthquake damage can be reduced. aftershock liquefaction tsunami CHAPTER RESOURCES SECTION OUTLINE

Earthquake damage can be reduced. 7.3 Earthquake damage can be reduced. Structures can be designed for greater safety in an earthquake. Walls can also be made stronger by adding braces. Pairs of braces that form an X shape are called cross braces. They help a structure keep its shape while it is being shaken. aftershock liquefaction tsunami CHAPTER RESOURCES SECTION OUTLINE

7.1 Earthquakes occur along faults. I. Earthquakes occur along faults. A. Rocks move along faults. stress B. Faults are classified by how rocks move. earthquake 1. Normal Faults 2. Reverse Faults 3. Strike-Slip Faults CHAPTER RESOURCES KEY CONCEPT SUMMARY

Earthquakes release energy. 7.2 Earthquakes release energy. II. Earthquakes release energy. seismic wave A. Energy from earthquakes travels through Earth. focus epicenter 1. Waves and Energy seismograph 2. Primary Waves 3. Secondary Waves 4. Surface Waves B. Seismic waves can be measured. 1. Using Seismographs CHAPTER RESOURCES 2. Locating an Earthquake KEY CONCEPT SUMMARY

Earthquake damage can be reduced. 7.3 Earthquake damage can be reduced. III. Earthquake damage can be reduced. aftershock A. Earthquakes can cause severe damage and loss of life. liquefaction 1. Earthquake Magnitude tsunami 2. Damage from Earthquakes 3. Damage from Tsunamis B. Scientists work to monitor and predict earthquakes. C. Structures can be designed to resist earthquake damage. CHAPTER RESOURCES KEY CONCEPT SUMMARY

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