How to Use This Presentation To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show”, or simply press F5 on the top row of your keyboard. To advance to the next slide click the left mouse button once. From the Chapter screen you can click on any section to go directly to that section’s presentation. Blank or “missing” areas of a slide will remain hidden until the left mouse button is clicked. You may exit the slide show at any time by pressing the Esc key Copyright © by Holt, Rinehart and Winston. All rights reserved.

Earthquakes Module F: Chapter 5 Section 1: What Are Earthquakes? Section 2: Earthquake Measurement Section 3: Earthquakes and Society Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

What Are Earthquakes? Section 1 Bellringer What do you think an earthquake is? Do you think the way earthquakes are portrayed on television and in movies is accurate? Why or why not? Write your answer in your science journal. Copyright © by Holt, Rinehart and Winston. All rights reserved.

What Are Earthquakes? Section 1 Objectives Explain where earthquakes take place. Explain what causes earthquakes. Identify three different types of faults that occur at plate boundaries. Describe how energy from earthquakes travels through the Earth. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

What Are Earthquakes? Section 1 Where Do Earthquakes Occur? Tectonic Plates Most earthquakes take place near the edges of tectonic plates. Faults As a result of tectonic plate movements, numerous features called faults exist in the Earth’s crust. A fault is a break in the Earth’s crust along which blocks of the crust slide relative to one another. Earthquakes occur along faults because of this sliding. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

What Are Earthquakes? Section 1 What Causes Earthquakes? Deformation Elastic deformation leads to earthquakes. Elastic Rebound The sudden return of elastically deformed rock to its original shape is called elastic rebound. Elastic rebound is illustrated on the next slide. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Elastic Rebound Section 1 Copyright © by Holt, Rinehart and Winston. All rights reserved.

What Are Earthquakes? Section 1 Faults at Tectonic Plate Boundaries Plate Motion Transform plate motion causes a strike-slip fault. Convergent plate motion causes a reverse fault. Divergent plate motion causes a normal fault. Earthquake Zones Most earthquakes happen in the earthquake zones along tectonic plate boundaries. Earthquake zones are places where a large number of faults are located. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

What Are Earthquakes? Section 1 How Do Earthquakes Travel? P Waves Waves that travel through solids, liquids, and gases are called P waves (pressure waves). S Waves After being deformed from side to side, the rock springs back to its original position and S waves are created. S waves, or shear waves, are the second-fastest seismic waves. Surface Waves Surface waves move along the Earth’s surface and produce motion mostly in the upper few kilometers of Earth’s surface. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquake Measurement Section 2 Bellringer Create a qualitative scale for gauging earthquake intensity. Describe the effects of very minor earthquakes and extreme earthquakes. What kind of damage would be done to buildings, water and power supplies, animals, forests, and people? Record your response in your science journal. Copyright © by Holt, Rinehart and Winston. All rights reserved.

Earthquake Measurement Section 2 Objectives Explain how earthquakes are detected. Describe how to locate an earthquake’s epicenter. Explain how the strength of an earthquake is measured. Explain how the intensity of an earthquake is measured. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquake Measurement Section 2 Locating Earthquakes Copyright © by Holt, Rinehart and Winston. All rights reserved. Determining Time and Location of Earthquakes Seismologists use seismograms to calculate when an earthquake began. Seismologists also use seismograms to find an earthquake’s epicenter. The S-P Time Method Perhaps the simplest method by which seismologists find an earthquake’s epicenter is the S-P time method. The next slide illustrates how the S-P time method can be used to find an earthquake’s epicenter. End of Slide

Finding an Earthquake Epicenter Section 2 Copyright © by Holt, Rinehart and Winston. All rights reserved.

Earthquake Measurement Section 2 Measuring Earthquake Strength and Intensity Copyright © by Holt, Rinehart and Winston. All rights reserved. The Richter Magnitude Scale Throughout much of the 20th century, seismologists used the Richter magnitude scale, commonly called the Richter scale, to measure the strength of earthquakes. Earthquake Ground Motion The Richter scale measures the ground motion from an earthquake and adjusts for distance to find its strength. Modified Mercalli Intensity Scale Currently, seismologists in the United States use the Modified Mercalli Intensity Scale to measure earthquake intensity. End of Slide

Earthquakes and Society Section 3 Bellringer If you have ever experienced an earthquake, write a short paragraph describing how you felt and what you did to protect yourself during the quake. If you have not experienced an earthquake, write a paragraph describing what you think you would do during a moderate earthquake. Do you know what to do in an earthquake, fire, tornado, or serious storm? Write your responses in your science journal. Copyright © by Holt, Rinehart and Winston. All rights reserved.

Earthquakes and Society Section 3 Objectives Explain how earthquake-hazard level is determined. Compare methods of earthquake forecasting. Describe five ways to safeguard buildings against earthquakes. Outline earthquake safety procedures. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquakes and Society Section 3 Earthquake Hazard What Is Earthquake Hazard? Earthquake hazard is a measurement of how likely an area is to have damaging earthquakes in the future. Area with a High Hazard The West Coast of the United States has a very high earthquake-hazard level because it has a lot of seismic activity. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquakes and Society Section 3 Earthquake Forecasting Strength and Frequency The strength of earthquakes is related to how often they occur. The Gap Hypothesis The gap hypothesis is a hypothesis that states that sections of active faults that have had relatively few earthquakes are likely to be the sites of strong earthquakes in the future. Using the Gap Hypothesis Some seismologists think the gap hypothesis helped forecast the approximate location and strength of the 1989 Loma Prieta earthquake. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquakes and Society Section 3 Earthquakes and Buildings Retrofitting The process of making older structures more earthquake resistant is called retrofitting. Earthquake Resistant Buildings Architects and engineers use the newest technology to design and construct buildings and bridges to better withstand earthquakes. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquakes and Society Section 3 Are You Prepared for an Earthquake? Before the Shaking Starts The first thing you should do is safeguard your home against earthquakes. Next, you should find safe places within each room of your home and outside of your home. When the Shaking Starts The best thing to do if you are indoors when an earthquake begins is to crouch or lie face down under a table or desk in the center of a room. After the Shaking Stops Remove yourself from immediate danger, such as downed power lines and broken glass. Be aware that there may be aftershocks. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

Earthquakes Chapter 8 Concept Map Copyright © by Holt, Rinehart and Winston. All rights reserved. Use the following terms to complete the concept map on the next slide: seismograph, seismic waves, earthquakes, surface waves, body waves, S waves.

Concept Map Chapter 8 Copyright © by Holt, Rinehart and Winston. All rights reserved.

Concept Map Chapter 8 Copyright © by Holt, Rinehart and Winston. All rights reserved.