Earthquake in the Classroom

1. Shake It Up Baby! Earthquake in the Classroom

2. On a piece of your own paper do the following assignment on today’s lab. Title it Shake it Up Baby – Seismic-Safe Buildings • Read Page 74 and 75 Seismic-Safe Buildings • List six features that buildings have in order to reduce earthquake damage. Explain how each works

3. Introduction • Earthquakes can cause much loss of life and millions of dollars worth of damage to cities. Surface waves and body waves from earthquakes can cause walls to crack, foundations to move and even cause entire buildings to crumble. Engineers continually strive to make buildings stronger to resist the forces of earthquakes. Copy this info on your assignment!!! P wave (primary wave) • A type of seismic wave that compresses and expands the ground S wave (secondary wave) • A type of seismic wave that moves the ground up and down or side to side Surface wave • A type of seismic wave that forms when P waves and S waves reach the Earth’s surface

4. Design • Engineers face the challenge of designing more robust buildings to withstand earthquakes. Earthquake-proof buildings will bend and sway with the motion of an earthquake, instead of cracking and breaking under the pressure. • Have you ever looked at a really tall building, such as a skyscraper? What does it look like? Does it appear fragile and unstable? It might, but it is most probably quite sturdy and can withstand wind, rain and other natural elements and phenomenon.

5. Design • Earthquake-proof buildings will typically have cross bracing that forms triangles in its design geometry (like a bridge). • Such buildings also normally include a large "footprint," or base, and a tapered shape, decreasing in size as the building gets taller (or simply, smaller at the top). • Short buildings are more earthquake proof than tall ones. Why do you think that is? Have you ever climbed up a tree or been on top of a playground jungle gym in the wind? Do you sway more when you are up high than when on the ground? • All buildings shake at the same frequency as the shaking of the earth, but the movement is magnified as the building gets taller. Sometimes, as can be the case during an earthquake, a building will sway too much, crack and crumble and fall. the area of ground covered by a building.

6. You will make models of buildings and conduct an experiment to test how well your structures stand up under the stress of an earthquake. Civil engineers do this as their job. • You and your partner have 30 toothpicks and 30 marshmallows. The Earth has limited resources, so therefore engineers also have limited resources when building structures. • You will make structures of toothpicks and marshmallows using only the materials you have been given. You may make large or small cubes or triangles by using whole or broken toothpicks. You may use cross bracing to reinforce their structures. Cubes and triangles may be stacked to make towers. The towers can have small or large "footprints" (or bases). • At the end of class carefully stack your “building” on a piece of paper with both your names and your period in the designated spot.

7. Draw a sketch of your structure. Measure and record its height, length, and width. Line a tray with a paper having you and your partner’s names. Set your structure in it and put it on the counter to dry overnight. Once your structure is built… • define in your own words – • cross-bracing, • large foot-print, • tapered geometry • YOU WILL BE ADDING INFORMATION TO THIS TOMORROW. PUT IT IN YOUR FOLDER

8. Today’s test • Today we will be testing by shaking your buildings on a bed of jello. I will be doing the motion and you will record your observations of what you see as I go for each structure. • We will rate each group’s structure with a • 4 (outstanding) • 3 (functional), • 2 (iffy) • 1 (deathtrap) • How did your structure do? • Really think about what works and what doesn’t. How would you redesign your structure based on your observations. Record this in “I’ve learned”. You should also be able to explain the difference between a P wave, S wave, and surface wave at the end of today’s activity.

9. Seismic Waves Demonstration http://sunshine.chpc.utah.edu/labs/seismic/index.htm

10. P Waves P waves (pressure or primary waves) travel as a region of compression. How would this appear? Using the diagram above, make the green dots move left and right. Observe what happens to the distance between the dots. • During compression, the dots move: A) closer together or B) further apart. • This wave is similar to the way A) sound or B) light waves travel through air. • As a P wave travels, the green dots vibrate back and forth A) parallel or B) perpendicular to the direction of wave travel. P waves are the fastest kind of seismic wave. A longitudinal P wave has the ability to move through solid rock and fluid rock, like water or the semi-liquid layers of the earth. It pushes and pulls the rock it moves through in the same way sound waves push and pull the air. Have you ever heard a big clap of thunder and heard the windows rattle at the same time? The windows rattle because sound waves push and pull on the glass much like P waves push and pull on rock. Sometimes animals can hear the P waves of an earthquake, but usually humans only feel the “bump” of these waves.

11. S Waves You may think of the Earth as a solid structure, but in fact the Earth’s crust is floating on a semi-liquid layer of molten rock (magma) just below the crust. Below that, S waves (shear waves) travel like vibrations in a bowl of Jello. • How would this appear? • Does the distance between the green dots change, or • is the rectangular shape between the dots distorted? • The movement of the green dots is A) parallel or B) perpendicular to the direction of the wave travel. As an S wave travels, the material is distorted but the green dots do not compress (the space between them pretty much stays the same.) S waves are the second wave you feel in an earthquake. An S wave is slower than a P wave and only moves through solid rock. This wave moves rock up and down, or side-to-side. Because P waves are compression waves, they can move through a liquid. However, S waves cannot move through a liquid. This is because a liquid is not rigid enough to transmit an S wave. S waves travel more slowly than P waves and, again, S waves cannot travel through a liquid.

12. P and S waves caused by an earthquake do not travel in straight lines. They also do not have a constant speed. • Do you think the wave would A) speed up or B) slow down as it moved further from the wave source? • Waves can reflect off (bounce off) of materials that have a different density, or they can be refracted (bent) as they pass through a boundary between layers of different material. Scientists use the difference in arrival times of reflected and refracted waves from distant earthquakes to construct a picture of what the Earth’s interior looks like. • P waves and S waves have allowed scientists to determine indirectly the internal structure of the Earth. Because these waves travel at different speeds through different material, they are also used to help determine the exact location of an earthquake (epicenter). Remember that these waves are transferring energy, and that energy is what causes the damage seen in the crust of the Earth, which is not plastic like the mantle and can break under pressure (causing faults!).