Name \( \qquad \) Date \( \qquad \) Class \( \qquad \) Earthquakes - Review and Reinforce Earthquakes and Seismic Waves Understanding Main Ideas Answer the following questions in the spaces provided. 1. What are seismic waves? \( \qquad \) \( \qquad \) 2. In what order do the three types of seismic waves arrive at a seismograph? \( \qquad \) \( \qquad \) 3. Which type of seismic wave produces the most severe ground movements? \( \qquad \) 4. Describe the moment magnitude scale, and explain why it is useful in measuring earthquakes. \( \qquad \) \( \qquad \) \( \qquad \) 5. How do geologists locate the epicenter of an earthquake? \( \qquad \) \( \qquad \) \( \qquad \) Building Vocabulary Match each term with its definition by writing the letter of the correct definition in the right column on the line beside the term in the left column. \( \qquad \) 6. focus a. records ground movements caused by 7. epicenter seismic waves as they move through the Earth 8. surface waves 9. seismograph b. slowest seismic waves that produce the most severe ground movements 10. magnitude c. the point beneath Earth's surface at which rock under stress breaks and triggers an earthquake d. a measurement of earthquake strength e. the point on the surface directly above the point at which an earthquake occurs © Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reseved.

**Earthquakes - Review and Reinforce** **Earthquakes and Seismic Waves** **Understanding Main Ideas** **1. What are seismic waves?** Seismic waves are energy waves generated by the sudden release of energy during an earthquake or other seismic events. These waves travel through the Earth's layers and are responsible for the shaking that occurs during an earthquake. **2. In what order do the three types of seismic waves arrive at a seismograph?** The three types of seismic waves arrive at a seismograph in the following order: 1. **Primary waves (P-waves)** 2. **Secondary waves (S-waves)** 3. **Surface waves** **3. Which type of seismic wave produces the most severe ground movements?** Surface waves produce the most severe ground movements. They travel along the Earth's surface and typically cause the most damage during an earthquake. **4. Describe the moment magnitude scale, and explain why it is useful in measuring earthquakes.** The moment magnitude scale is a measurement system used to quantify the size of an earthquake. It calculates the total energy released by an earthquake by considering factors such as the fault length, the amount of slip on the fault, and the depth of the earthquake. This scale is useful because it provides a more accurate and consistent measure of an earthquake’s size, especially for large and distant earthquakes, compared to older scales like the Richter scale. **5. How do geologists locate the epicenter of an earthquake?** Geologists locate the epicenter of an earthquake by using data from at least three different seismograph stations. They measure the distance of the epicenter from each station based on the time difference between the arrival of P-waves and S-waves. By drawing circles with these distances around each station, the point where all circles intersect is identified as the epicenter. --- **Building Vocabulary** Match each term with its definition by writing the letter of the correct definition in the right column on the line beside the term in the left column. | Term | Definition Letter | |---------------|--------------------| | **6. focus** | c. the point beneath Earth's surface at which rock under stress breaks and triggers an earthquake | | **7. epicenter** | e. the point on the surface directly above the point at which an earthquake occurs | | **8. surface waves**| b. slowest seismic waves that produce the most severe ground movements | | **9. seismograph** | a. records ground movements caused by seismic waves as they move through the Earth | | **10. magnitude** | d. a measurement of earthquake strength | --- **Answer Key for Building Vocabulary:** 6. c 7. e 8. b 9. a 10. d