Earthquake Early Warning - California State University .

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Earthquake Early Warning Lesson PlanOverviewIn this sequence of activities, students will learn that scientists learn about seismic waves so that they canhelp make people safer. Students will make observations of a real earthquake from a video and discoverthat there are different types of seismic waves. Kinesthetic activities will help them understand how thesedifferent seismic waves work and how they affect what a person feels during an earthquake. With thisfirm conceptual understanding and a picture of a real situation, they will make simple mathematicalcalculations to see how long it takes for these waves to travel. They will be motivated to want to makethese calculations because the culminating activity is to design an earthquake early warning system tomake their own school safer. Math is a key tool in designing that system.This sequence of activities is designed to last about 3 class sessions.Teacher BackgroundEarthquake early warning systems do not predict earthquakes before they happen. Instead, they rely onseismic sensors to detect shaking and alert people. Since earthquake waves start at the source and spreadout, you can place seismic sensors close to the earthquake source. They can beam their warning signal atthe speed of light to surrounding areas. While seismic waves travel faster than the fastest jet airplanes,they still take longer to travel than light. That means that the warning signal will reach nearby cities a fewseconds before the damaging earthquake waves. The closer a sensor is to the earthquake source, the morewarning time it will provide.Early warning systems are not science fiction. There are systems currently in place in Japan and MexicoCity, as well as systems being tested in other areas like southern California. They provide a crucial fewextra seconds that can be used to stop bullet trains, medical procedures, and give school children time toprotect themselves under their desks. It's not enough time to evacuate a city (or even a building in manycases), but it can be enough to save lives and money.Read more on the links from this website: In particular, werecommend this news article /c/a/2003/05/05/MN82287.DTL and this 10 minute movie .Activities1) Why does this man interrupt his lunch? (20 minutes)2) Understanding Seismic Waves - Direct Instruction (30 minutes)3) Kinesthetic early warning (30 minutes)4) Early warning game (1 class session)Earthquake Early Warning Lesson Outlinep. 1

Grade 6 Content Standards for CaliforniaScience: 1g. Students know how to determine the epicenter of an earthquake and know that the effects ofan earthquake on any region vary, depending on the size of the earthquake, the distance of the region fromthe epicenter, the local geology, and the type of construction in the region.Math: Algebra & Functions:1.1Write and solve one-step linear equations in one variable2.2Demonstrate an understanding that rate is a measure of one quantity per unit value ofanother quantity.2.3Solve problems involving rates, average speed, distance, and time.Formative Assessment/Link to previous contentDuration: 5 minutesMaterials: NoneKey Concepts: Earthquakes are caused by sudden sliding of earth’s tectonic platesSequence:1) Teachers can motivate the relationship between earthquakes and plate tectonics with a simplekinesthetic formative assessment: have students place their arms out in front of them, eacharm representing one of Earth’s tectonic plates. Ask them to use their arms to show how anearthquake happens. Students may be tempted to simply crash their hands into one another,but an earthquake always involves sliding of one plate over/above, under/below, or sidewayspast another plate. A proper demonstration also has the arms stationary for a long period oftime and then a sudden motion. That’s an earthquake, and the sudden-ness is one reason theyare so damaging. This activity explores one way to deal with the fact that earthquakes occurseemingly without warning.(Thanks to da Vinci’s Vetruvian Man for these public domain images of hands)Earthquake Early Warning Lesson Outlinep. 3

Activity 1: Why does this man interrupt his lunch?Students enjoy this video of a man eating his lunch during an earthquake, which visually illustrates thedifferent pulses of shaking during an earthquake.Duration: 20 minutesMaterials: Computer and projectorKey Concepts: Every earthquake involves at least two pulses of shaking: an early pulse that is usuallyweaker and a later pulse that is stronger and more damaging.Sequence:1) Motivate students: Ask them if they have ever felt an earthquake. If so, describe what they felt.Solicit a few responses. If students have never felt an earthquake, ask them what they think wouldhappen during one. Would the shaking be strong? How long would it last?2) Tell students: “You will see a video of a very large earthquake that did lots of damage in Seattlein 2002. It caused about 400 injuries and millions of dollars in damage, but nobody was killed.The video is less than a minute, and we’ll watch it two times.”3) Show video of man eating sandwich during 2002 Seattle earthquake( q7boO wTzS4)4) Tell students: “Take out a piece of paper. The second time we watch the video, write down thesequence of every event you see and the order you see it. For example, we should all start withevent 1) Man sits down to eat lunch.” Write on the board:1) Man sits down to eat lunch2)3).or a simple table:TimeHow Severe is shaking?How can you tell shaking is happening?0:00No shaking yetMan sits down to eat lunch like everything is normal.5) Replay the first 45 seconds or so of the video.6) Have students get in pairs to make a single complete list.7) At 6 seconds into the video, the man looks up from his sandwich. Someone in the room says,"Earthquake" and another chimes in, "big earthquake," but the camera has not shaken enough tomove yet. At 14 seconds, the lunch-eater and others in the office stand up and leave the room. At20 seconds, the room starts to shake enough that computers rattle and shake. By 40 seconds, theshaking is over and the room is quiet.8) Ask students, "Why does the man in the office look up at 6 seconds? How do they know there isan earthquake? [they must have felt it]9) Ask the students, "When is the shaking strongest?" [after the people have left the room]10) Emphasize key concept: “So we seem to observe a weak pulse of shaking first and then a strongpulse of shaking later. The time between the first pulse and the strong pulse gave the people timeto better prepare themselves for the strong shaking. I wonder if all earthquakes work that way?And if so, why?”Earthquake Early Warning Lesson Outlinep. 4

Optional Extension: View seismic waveformsStudents can actually see the two pulses of shaking and their relative strength in actual seismograms. Thisreinforces what they saw in the videos.Duration: 20 minutesMaterials: Waveform printouts, optional computer projector.Key Concepts: Every earthquake involves at least two pulses of shaking: an early pulse that is usuallyweaker and a later pulse that is stronger and more damaging. Graph readingSequence:1) Tell students: “We want to know if all earthquakes work like the one in the video clip withtwo pulses of shaking. Rather than look at video clips of different earthquakes, we’re going tolook at graphs of precise measurements of earthquake shaking from sensitive seismicrecording devices. Like real earthquake scientists, we are going to look at the shaking graphsto see if we can spot a pattern – something that all the different recordings have in common.”2) Pass out shaking graphs. They are from a small earthquake near San Francisco in 2007.Many, but not all people felt the earthquake. Each shaking graph is recorded in a differentcity near San Francisco. Scientists study small earthquakes like this one to learn more aboutbig earthquakes.3) Walk students through the different axes of the graph: “Each seismogram has a three or fourletter ID that is an abbreviation for the city or location of the seismic recording instrument.The lines on the graph represent how quickly the earth moved up (positive) and down(negative). As the lines get really tall, that means that the shaking is stronger. Each graph hasdifferent numbers on the vertical axis because the shaking was different strengths at differentlocations. Who thinks they have the highest number for shaking velocity on their graph?[station CYB, axes run from 600 to -800. Strongest shaking felt was 600 microns/s downward(negative 600)]. The horizontal axis shows time. When did people in your city first feelshaking? Draw an x on your graph.” Circulate to check answers. [all the seismograms wereintentionally made so that the graph starts at time zero and shaking starts around 20 seconds.For some stations with low shaking velocity, the time from zero to 20 seconds looks likethere is shaking but this is just the regular background vibrations that are always present.]4) How long did the shaking last for? [Answers vary for the seismograms, but strong shaking istypically over by about 40 seconds on the graphs, so 20 seconds duration is a good answer.There was weak shaking all the way out to 80 seconds visible on some graphs.]5) Tell students, “Circle the point on the graph with the strongest shaking.” After circulating tomake sure that students are marking the highest amplitudes on the graph (either positive ornegative – remember that negative just means downwards!).6) Ask students, “Raise your hand if the ‘X’ you drew when shaking started is at the samelocation as the circle you just made when the shaking was the strongest.” [Nobody shouldraise their hand.]7) Link the observations in the seismograms to the observations in the video: “In the video, wenoticed that shaking was weak at first, got really strong, and then died off slowly. Can we seeevidence for that in the seismograms? In both examples, there seem to be two pulses ofshaking – a weaker first pulse and a stronger second pulse.” [You might even emphasize thatmost of the seismograms have a short pulse of shaking with medium strength, the shakinggets a little less for a bit, and then there is a sudden arrival of strong shaking.]Earthquake Early Warning Lesson Outlinep. 5

Activity 2: Understanding Seismic Waves – Direct instructionDuration: 30 minutesMaterials: Computer projector (with sound), presentation file for Activity 2.Key Concepts:1) Energy can move through the earth by moving particles of soil in different directions calleddifferent types of "seismic waves."2) Because they move through the earth differently, some types of seismic waves travel throughEarth faster than others.3) Because earthquakes are are caused by sliding plates, there is more energy released assliding-motion seismic waves (S-waves). So S-waves are stronger than P-waves for mostearthquakes.Sequence:1) Tell students: “To understand what causes those two pulses, we need to look more carefullyat what earthquakes are and what causes them.” Show a 2 minute video clip from the TVmovie 10.5. It reminds us that plates move and get stuck.2) “An earthquake is the name we give to the event where two plates (blocks of crust) lurchsuddenly past one another.” Earthquake sudden plate motion & shaking3) “One thing the video does not mention is that in an earthquake, only a small section of theplate boundary slips at one time. Let’s model this motion to see what happens. This piece ofpaper represents a plate boundary.” Pass out half sheets of paper with the printout of the plateboundary. “ [This model represents all types of plate boundaries, not just transform plateboundaries -- Even at plate boundaries where two plates crash together, one plate slides underthe other. In that case, this paper would represent a cross section. For a transform fault, itwould represent a map view.]Earthquake Early Warning Lesson Outlinep. 6

4) Have students hold their hands on the arrows to represent the relative motion of two plates asthey slide past one another. An earthquake is the sudden movement, so have them move theirhands suddenly.5) Ask students, “where is the paper pushed together? Where does it look like it’s being pulledalong? Where are two papers sliding past one another?” Label them on the board and havestudents label their papers.6) “So everywhere you labeled the word ‘push’, bits of rock near the plate boundary aresuddenly pushing against nearby rocks like a hammer smashing into the ground. That willsend pushing vibrations through the earth. We feel those as one form of seismic waves.”7) Show an animation of P-waves on the computer. Emphasize the push-pull particle motion.Pulling is just the opposite of pulling. So both pushing and pulling produce P-waves.8) “All along the fault, the rock slides along in a motion like ripping a paper. This is calledshear. The sudden shear in an earthquake moves through the Earth too, but differently thanthe P-waves.”9) Show an animation of S-waves on the computer. Emphasize the side-to-side motion thatcomes from the sliding that we call shear.10) Optional: Do a classic slinky demo or a human conga line showing the different wave types.11) Have students fill out the ‘motion’ column of the seismic wave table, emphasizing the firstletters as memory “Side-to-Side”(from sliding)SlowerLeavesource*Both leaveat the econdStronger12) “P-waves and S-waves move the rock differently – P-waves by pushing/pulling and S-wavesby shear or sliding. If you push on things, they actually behave differently than if you shearthem. Let me show you what I mean. Hold your plate boundary paper near the top and trypulling it apart. Does it break? The paper is very strong when you push it. Now, let’s try tomodel shear. You do that by pulling your paper in different directions – ripping it. Does itbreak? That’s because paper is weaker when you shear it than when you push it. Rock isexactly the same way. It’s stronger than paper, but there is a difference in its strength. Whenrock is rigid and strong, it transmits energy really quickly. When it is weaker, energy doesn’ttravel as quickly through it and waves will travel slower.” Write Stronger material wavestravel faster; weaker material waves travel slower. “Which will be travel faster in rock, Pwaves or S-waves?” [P-waves push rocks in a way that they are very strong and rigid, so Pwaves travel fast. S-waves shear rocks in a way that they are less strong and rigid, so S-wavesdon’t move as quickly through rock. They travel slower.]13) Have students fill out the Speed column of the table, emphasizing the S in Slower. For theLeave source column, have students play with their plate boundary paper and see that thepushing and pulling happens at the exact same time as the sliding, so both waves leave thesource at the same time. Since one is faster, they should also be able to fill out the Arrivaltime. Emphasize the “S” in second!14) “Wow, now we know why the guy eating lunch felt that first pulse of shaking that told him anearthquake was happening. But it was really weak and the second pulse was stronger. Whywas that? To answer that question, we can return to our plate boundary paper. Everywhereyou labeled push or pull write a big P. Everywhere that there is sliding, write big S’s. There isa lot of sliding, so write a lot of S’s. Remember that earthquakes are mostly caused by slidingEarthquake Early Warning Lesson Outlinep. 7

plates, so there is a lot more energy released by sliding than there is by pushing or pulling.That makes S-waves Stronger.15) Fill out the Strength column of the table.16) As you move the paper, notice that the sliding and the pushing happen together (at the sametime). This should make sense: Think about a massive ship in the ocean. When it starts tomove forward, which moves first, the front of the boat, the middle of the boat, or the water infront of the boat? The boat can’t move forward until the water gets out of the way and thewater doesn’t have any reason to move until the boat pushes it. They all move at the sametime, and the same is true in the rocks surrounding the plate boundary. P-waves and S-wavesget released at the same time because the movements all occur together. Have studentscomplete the Leave Source column of the table.17) Test for understanding:The most damaging seismic waves are:P-waves are felt before S-waves because:a) P waves because they are fastera) P-waves leave the earthquake source before Sb) P waves because they carry more energywavesc) S waves because they are fasterb) The side-to-side movement of S-waves cannot bed) S waves because they carry more energyfeltc) The forward/back movement of P-waves cannotbe feltd) P-waves travel faster than S-waves throughrock18) Now, return to the observations of the video in Activity 1. Have students explain what wasgoing on using their new terminology of P-waves and S-waves. When did each arrive?19) [Advanced topic to enhance teacher understanding: If an earthquake ruptures the entire plateboundary instead of just one segment, will there be any P-waves at all? Remember that weonly draw P’s at the end of the segment that ruptures. If the entire plate boundary ruptures atonce, there won’t be any P-waves. However, real earthquakes don’t have the entire plateboundary moving simultaneously or even the entire section of the plate boundary moving asone piece. Instead, one small section of the plate boundary starts to slip, which triggers thenext section, which triggers the next section. At each stage in the rupture, there is a part of theplate boundary that is slipping and a part that is not slipping. The parts that are slippingpush/pull on the adjacent parts, so P-waves are always produced.]20) [References for scientists: Small earthquakes recorded with acoustic emissions in SouthAfrican Gold Mines show 5 times more energy in S than 50274/abstract; Theory derives a factor of 10when you account for P-S conversions: papanico/pubftp/ptos.pdf.In terms of actual observations, S-wave amplitudes average about 5 times higher than P-waveamplitudes for small earthquakes, shearer/mahi/PDF/83SSA03a.pdf, though the ratio variesconsiderably based on the direction to the observation station compared to the direction thefault slipped.]Optional extension: Human Conga LineThis kinesthetic activity demonstrates the difference between different types of seismic waves. It helpsillustrate why the people felt two pulses of shaking in the earthquake movie of Activity 1.Duration: 5 minutesMaterials: space to line the class upEarthquake Early Warning Lesson Outlinep. 8

Key Concepts:21) Energy can move through the earth by moving particles of soil in different directions calleddifferent types of "seismic waves."22) Because they move through the earth differently, some types of seismic waves travel throughEarth faster than others.Sequence:5)6)7)8)9)10)11)12)13)1) Have students line up in a long line all facing the person in front of them (as ifthey were ready to walk out of the room for a fire drill)2) Have each student place his/her hands on the shoulders of the person in front ofthem.3) Tell students that they represent the ground. They are individual particles of rockand soil. Because the soil is a solid, each particle is connected to its neighbors."Once you feel shaking, pass that energy further along the line. But please begentle so nobody gets hurt. We want this to be an earthquake simulation, not anactual earthquake where people get hurt!"4) The teacher should go to the back of the line. Tell students, an earthquake sendsseismic energy through the earth by causing the ground to shake. "I represen

Earthquake early warning systems do not predict earthquakes before they happen. Instead, they rely on seismic sensors to detect shaking and alert people. Since earthquake waves start at the source and spread out, you can place seismic sensors close to the earthquake source. They can beam their warning signal at the speed of light to surrounding .

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