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IDefining an EarthquakeDefining an EarthquakeAn earthquake is a natural occurrence, like rain.Earthquakes affect almost every part of the Earthand like rain they can be either mild or catastrophic.Over the course of geological time, earthquakes,floods, and other natural events have helped toshape the surface of our planet.An earthquake may last only a few seconds, but theprocesses that cause earthquakes have operatedwithin the Earth for millions and millions of years.Until very recently, the cause of earthquakes was anunsolved mystery. It was the subject of fancifulfolklore and equally fanciful learned speculation bypeoples throughout the world.In a legend from Siberian Kamchatka, a god named Tuli drives anEarth-laden sled pulled by flea-infested dogs. When the dogs stop toscratch, the Earth shakes.***Some say the Earth was fevrous [feverish] and did shake.Shakespeare, Macbeth, IIIIn the mid-1960s, many scientific observations andexplanations of earthquakes came together in thetheory of plate tectonics. We’ll be exploring thatsubject in later units. In this unit we consider bothscientific and popular explanations for the phenomenon and look at the patterns of earthquake occurrence worldwide.An Earthquake Is . . .An earthquake is a sudden, rapid shaking of theEarth caused by the release of energy stored inrocks. This is a brief definition which students of allages can master. A full definition of the term, however, would need to include a good deal moreinformation.Students may be surprised that we speak of rocksand rock layers, because in many places the rockmaterial of the Earth’s crust is covered by accumulations of sand or soil. Remind them that even beneaththe sediment in river valleys, plains, and beachareas, some kind of rock is always present.10 EARTHQUAKES-FEMA 159

Defining an EarthquakeIEarthquake shaking may cause loss of life and destruction of property. In a strong earthquake theground shakes violently. Buildings may fall or sinkinto the soil. Rocks and soil may move downhill at arapid rate. Such landslides can bury houses andpeople.Folklore and Scientific TheoryPressure DirectionDeformed RocksFaultEarthquake WavesBecause strong earthquakes have such disastrouseffects, it is not surprising that people have alwayslooked for ways to explain their origin. We find manynonscientific explanations of earthquakes in thefolklore of civilizations around the world. We callthese traditional narratives earthquake legends.Some of them are still being told today.What we have learned in recent years, however,largely from the study of earthquakes, is that theEarth around us is not static, like a stage set for aplay. The Earth’s rock layer is broken into largepieces. These pieces are in slow but constant motion.They may slide by smoothly and almost imperceptibly.From time to time, the pieces may lock together, andenergy that accumulates between the pieces may besuddenly released. This sudden release of energy,like the snapping of a rubber band that has beenstretched too far, is what we call elastic rebound.Energy is released and travels through the Earth inthe form of waves. People on the surface of the Earthexperience an earthquake.FaultEpicenterFocusEarthquake WavesEARTHQUAKES-FEMA 159 11

IDefining an EarthquakeEarthquake EpicentersThe epicenter of an earthquake is the place on theEarth’s surface directly above the focus (or hypocenter),the place inside the Earth where the quake originates.Earthquake foci are usually somewhere between thesurface and 100 km in depth. In some areas, however,foci may be as deep as 700 km.Even a glance at an earthquake epicenter map showsthat most earthquakes have occurred in certain welldefined regions of the Earth. Because these regionstend to be relatively long and narrow, they are sometimes referred to as earthquake belts.One large belt of epicenters runs through the Mediterranean Sea, Asia Minor, the Himalayan mountains,and into the eastern Indian Ocean. A second large beltruns northward through the western Pacific Ocean, theJapanese islands, the Aleutian islands, and the westcoasts of North and South America. The longest belt ofearthquake epicenters runs through the central regionsof most ocean basins. The world epicenter map alsoshows some shorter belts of epicenters.Chances are, even if your school is far from any earthquake epicenter, your students already have someideas about earthquakes and what causes them. In thelessons that follow, you will invite them to tell you whatthey think.Master 7, World Map with Epicenters. The dots represent earthquakes with magnitudes 5.0 recorded from 1980-1990 by theNational Earthquake Information Center, USGS.12 EARTHQUAKES-FEMA 159

Defining an Earthquake/ Unit I, Level 1, Grades K-2IWhat Is an Earthquake?Content Concepts1. An earthquake is a sudden, rapid shaking of the Earthcaused by the release of energy stored in rocks.2. Legends are traditional narrative explanations of natural phenomena that evolve when scientific explanationsare not dents will—describe personal experiences with earthquakes.—construct an earthquake model.—observe effects of a simulated earthquake.—define the term legend, and listen to a legend.—suggest possible causes of earthquakes.—write and illustrate original legends.—draw pictures to illustrate their ideas about the Earth’sinterior.AssessmentRestate The Turtle Tale. Draw or tell three imaginative,non-scientific explanations for Earth movement.Learning LinksLanguage Arts: Writing a descriptionof a demonstration (older students),sharing ideas about the possible causes ofearthquakes, building vocabulary, listeningto a legend, creating an original legendArt: Illustrating the legends, expressingideas about the Earth’s interior in drawing,contributing to a muralSocial Studies: Observing the effectsof a simulated earthquake on modelbuildings, predicting the effects onpeople’s lives, discussing a NativeAmerican legend, locating San Gabrielon a U.S. mapEARTHQUAKES-FEMA 159 13

IDefining an Earthquake/ Unit I, Level 1, Grades K-2Activity One: Tremble Here, Tremble ThereMaterials for the teacher A small table or desk that moves easilyMaterials for each small group of students A shallow box partially filled with sand or soil An assortment of paper plates, cups, and small boxes thatcan be stacked to represent a building.Procedure1. Introduce the topic with a class discussion based on thefollowing questions:What does the word quake mean?What do we mean when we say people are “quaking intheir boots”? (Invite students to imitate a persontrembling.)Have you ever been on a bridge when it shook from heavytraffic, or near the railroad tracks when a train passedover? (Invite students to demonstrate shaking and vibrating.) What do you suppose is happening to the Earthwhen there is an earthquake?Has anyone here ever felt an earthquake? (Allow studentstime to express their observations and feelings.)14 EARTHQUAKES-FEMA 159earth quakeAn earthquake is a sudden, rapidshaking of the Earth caused by therelease of energy stored in rocks.leg endsLegends are traditional narrativeexplanations of natural phenomenathat evolve when scientific explanations are not available.

Defining an Earthquake/ Unit I, Level 1, Grades K-2I2. Tell students they are going to make a model to demonstrate what happens during an earthquake. Follow thesesteps:a. Invite a small group of students to pile plates, cups,and small boxes on top of each other in thefilled box to form a tall structure. (Either haveenough materials for each group to constructone model, or have the groups take turns.)b. Place the large box on the cart, table, or desk.c. Shake the cart, table, or desk until the structuretopples.d. Ask the students to comment on what they see.What does the sand or soil represent? (the Earth)What do the plates, cups, and boxes represent? (atall building)What moves? (the Earth and the building)What happens to the building? (various degrees ofdamage)Children will enjoy simulatingvarious levels of force andobserving the results.EARTHQUAKES-FEMA 159 15

IDefining an Earthquake/ Unit I, Level 1, Grades K-2Activity Two: Tremors and TurtlesMaterials for the teacher Master 1a, U.S. Map Master 2, The Turtle TaleMaterials for each student 2 small (6") paper plates 1 straw Green construction paper Handout from Master 3, Turtle Tale Pop-Up Puppet Scissors Markers or crayons StaplerProcedure1. Discuss the origin of legends.How can we understand about earthquakes? (fromscience)Yes, but earthquakes have been happening for a longtime, and we have only been studying them with scientific instruments for a short time. How do you supposepeople explained them before that? (with stories)These stories are called legends.16 EARTHQUAKES-FEMA 159Teacher Take Note: See the Appendix, Earthquake Legends, for moretremor tales from around theworld.

Defining an Earthquake/ Unit I, Level 1, Grades K-2I2. Point out the San Gabriel Valley on a U.S. map. (Indicate the southwestern part of California, in the neighborhood of Los Angeles—see map.)*3. Introduce the story on Master 2, The Turtle Tale, andread it aloud. This is a story that was told by a group ofNative Americans who lived where earthquakes are common, in the San Gabriel Valley. People call them theGabrielinos (Ga bree uh leé nos).4. Discuss the story.Did you enjoy the story? Why or why not?Master 1a, U.S. Map. San Gabriel ismarked with an asterisk (*)Do you think the story is true? Why or why not? (Students will give a variety of reasons why it is not: Turtlesare not that big. Turtles are not that strong. Turtlescan’t talk.)Why do you think the Indians developed this story?(When an earthquake or any other frightening eventoccurs, people want to understand what causes it.Understanding helps them to be less afraid.)Have you ever asked an older person to explain something that frightened you, and felt better afterwards?Teacher Take Note: Encourage olderstudents to design their own puppets.Younger students may enjoy the turtledot-to-dot exercise. (Master 4)5. Have students make a Turtle Tale Pop-Up Puppet.Distribute Master 3 (pattern) to students and give theseinstructions:Staple plates together top to top creating a roundedshell for the turtle.Copy pattern onto green construction paper.Cut out 4 feet, 1 head, and 1 tail.Attach feet onto shell (paper plates).Staple tail to one end of the straw and the head to theother.Slip straw between plates at a space between staples.Decorate the shell.Pull the tail to make the head go into the shell. Pushthe tail to make it come out again.6. Have students act out the legend of the Turtle Talewith their puppets. You will need seven students toportray the turtles and one for the Great Spirit. Studentscan mime the action and dialogue as the teacher readsaloud.EARTHQUAKES-FEMA 159 17

IDefining an Earthquake/ Unit I, Level 1, Grades K-2Activity Three: Earth MuralMaterials for the teacher A large roll of paper for the muralMaterials for each small group of students Drawing paper and crayons or oil pastels ScissorsProcedure1. Ask each student to draw a large circle representing theEarth and draw a picture of what there might be inside tomake it move. Help students dictate or write explanationsthat match their drawings.2. Create a class mural by directing the students to cutout their drawings and paste them to a large piece ofpaper. The explanations students have written or dictatedmay be displayed beside the drawings.3. Share all the student stories and the legends. Accept allideas without evaluation. End the lesson without providing any further information as to the actual causes ofearthquakes. (Direct curious students to children's encyclopedias and other classroom or library reference materials. When the discussion resumes in the next lesson, youwill find that students have gained some information ontheir own.One group of first graders made thesedrawings of the Earth’s insides.18 EARTHQUAKES-FEMA 159Extensions1. Ask students to create their ownlegends to explain earthquakes. Havethem dictate, draw, or write theirstories.2. Act out the original legends withpaper bag puppets. Provide lunchbags and art materials. Give thestudents time to make their puppetsand rehearse before the final presentation.3. Ask the children to describe animaginary journey to the center of theEarth. What might they find there thatcould cause earthquakes?

Defining an Earthquake/ Unit I, Level 2, Grades 3-4IPeople Explain EarthquakesContent Concepts1. An earthquake is a sudden, rapid shaking of the Earthcaused by the release of energy stored in rocks.2. Legends are traditional narrative explanations of natural phenomena that evolve when scientific explanationsare not available.3. Earthquake energy is released in the form of waves.VocabularyearthquakelegendcultureLearning LinksLanguage Arts: Class discussion, writingexpository paragraphs, sharing ideasObjectivesStudents will—describe personal experiences with earthquakes.—write and illustrate a paragraph about what theythink causes earthquakes.—read and illustrate earthquake legends.—locate the cultures that developed the variouslegends on a world map.—compare these locations to the major areas ofearthquake activity around the world.—state what scientists now believe is the cause ofearthquakes.—observe the effects of a simulated earthquake.AssessmentExplain or draw a picture of what scientists believe is thecause of earthquakes.Social Studies: Locating countries on theworld mapArt: Illustrating students’ earthquaketheories, illustrating legendsEARTHQUAKES-FEMA 159 19

IDefining an Earthquake/ Unit I, Level 2, Grades 3-4Activity One: Earthquake ExperiencesMaterials for the teacher Magazine or newspaper accounts of earthquakes, orbooks, slides, movies, and other media dealing with thesubjectMaterials for the students Drawing paper Crayons or markers TapeProcedure1. Begin a discussion by asking students what they thinkan earthquake is. List responses on the board.2. Ask if any of your students has ever experienced anearthquake. Invite those who have to share their experiences with the class.3. If the students do not have much personal experienceto draw on, use some of the resources suggested above toprovide a basis for the unit. You may also want to invitesomeone who has experienced an earthquake to visit theclass.4. Distribute paper and art supplies. Ask the students tomake drawings illustrating what they think causes earthquakes. They may write paragraphs to accompany thepictures and combine them as a display for the wall orbulletin board. Volunteers can present their ideas to theclass. Make no comments about the correctness of theirideas at this point.20 EARTHQUAKES-FEMA 159earth quakeAn earthquake is a sudden, rapidshaking of the Earth caused by therelease of energy stored in rocks.leg endsLegends are traditional narrativeexplanations of natural phenomenawhich evolve when scientificexplanations are not available.cul tureA culture is the special way of lifecommon to a group of people.

Defining an Earthquake/ Unit I, Level 2, Grades 3-4IActivity Two: Earthquake LegendsTeacher Take Note: Some of theselegends come from parts of the worldwhere quakes do not occur frequently. An earthquake is a highlydramatic, memorable event. Somecultures may have borrowed oraltraditions based on events outsidetheir own geographic region. Othersmay have carried legends with themas they migrated from one part of theglobe to another. Be prepared to finda less than exact correlation betweenlegends and earthquake activity.Materials for the teacher Large wall map of the world, or transparency madefrom Master 5, World Map Tape or pins Colored yarn Transparency made from Master 6, World Map withLegend Sites Transparency made from Master 7, World Map withEpicenters Overhead projectorMaterials for each student Booklet of earthquake legends (See Appendix) Large sheets of drawing paper Crayons or markersProcedure1. Explain that earthquakes have been happening onEarth for millions of years. Scientists have understoodwhat causes them for less than 50 years. People whoexperienced earthquakes developed traditional explanations that suited their culture, or way of life. We call theseexplanations legends.Master 6, World Map with Legend SitesEarthquake Legend Sites Key1. India2. Assam, betweenBangladesh and China3. Mexico4. Siberia5. Japan6. Mozambique7. Greece8. Belgium9. Tennessee USA10. West Africa11. Mongolia12. India13. Latvia14. Colombia15. Scandinavia16. New Zealand17. East Africa18. Central America19. Romania20. West AfricaEARTHQUAKES-FEMA 159 21

IDefining an Earthquake/ Unit I, Level 2, Grades 3-42. Distribute art materials and copies of the legends toevery student. Divide the students into groups and haveeach group illustrate one of the legends. Label each illustration with the name of the culture or the region of theworld it comes from.Teacher Take Note: You may want toread all the legends with the studentsbefore they begin to draw.3. On a world map, locate the region where each

Master 34. P-Wave Motion and S-Wave Motion Master 35. The S-Wave Machine Master 36a. KWAT Television Script Master 36b. Wattsville Map Master 36c. Wattsville Map Key UNIT V Master 37. Earthquake Hazard of the U.S. Master 38. Earthquake Simulation Script Master 39. Drop, Cover and Hold Master 40. Coalinga Schools Report Master 41. Fourth Grade .