Earthquake+S+and+P+Waves

= Earthquake S and P Waves = Jeff Kiel (__ jgk5048@psu.edu __) Ethan Maneval (__ eem5117@psu.edu __)

Topic: Earthquake S and P Waves Grades: 6-8 Group Size: 3-5 Students

NSE Standard(s) Use appropriate tools and techniques to gather, analyze, and interpret data. PA Standard(s) 3.5.7A Describe major layers of the earth. 3.7.7D Apply computer software to solve specific problems. 3.4.7C Evaluate wave properties of frequency, wavelength and speed as applied to sound and light through different media.

Objectives: Students will be able to distinguish between and model S and P waves using a slinky Students will be able to collect information about the differences in intensity when variables such a distance and depth are changed using SeisMac. Students will able to distinguish between the layers of the earth and their properties relative to one another.

Content: This lesson centers on the concept of waves generated by seismic activity. The two waves that this lesson concentrates on are the primary (P) and secondary (S) waves of an earthquake. P waves are compression waves, which can travel both through liquids and solids. These waves travel faster than S waves and are the first ones to arrive at a detector (seismometer). S waves arrive right after the P waves. They cannot travel through liquids however. The students, with the use of a slinky, should roughly demonstrate the wave types and relative speeds. First the students should be asked to create different types of waves using the slinky then after introduction of the two earthquake waves should be able to connect these types to those modeled by the slinky. The second activity should be to explore earthquake detection using the SeisMac program. Students should be asked to explore what different properties can affect the detection of seismic activity. This includes the idea that intensity diminishes with distance and depth, the liquid outer core of the earth causes a "shadow" in the readings, scientists estimate the composition of the core based upon seismic readings because S waves cannot travel through liquid.

Safety- Make sure that when students are testing using the computers that the computer is stable and will not fall. Students do not need to use much force when testing and should be instructed not to do so for their safety and that of the equipment.

Materials and Setup - Slinkys (2) - Computer with SeisMac (1) - Lab table (1) - Map of North America (1) - Textbooks (4-10) - Picture of S and P waves on a seismograph from a real earthquake - Diagram of blind spots of waves in earth's interior **Engagement:** (2-3 min) What is an Earth Quake? What causes earth quakes? Do people experience earth quakes at different times when they live in different areas or do they feel the earth quake at the same time? What else can you share about earthquakes? **Exploration:** (~10 min) Guiding question: How do earth quakes travel? What is the difference between S and P waves and how they affect the surface? -As a group designate two people to hold the slinky on either side of the table -Have another group member create a wave with the extended slinky -Can you make the wave move faster? Can you make the wave bigger? Is there another kind of wave you can make? -Have students create the second type of wave -Can you make this wave bigger or smaller, slower or faster? What is the difference between the two waves? - The "P" in p-wave stands for primary because it is the first wave to reach a detection site, it travels faster than the s-wave as we saw in our activity (show picture from real seismograph -The "S" in s-wave stands for secondary wave. Is called a secondary wave because it reaches detection sites after p-waves. Make note to students that the way this wave moves, in an "S" shape, is the same as the letter "s" in __S__econdary  -Collect the slinkies and bring out the computer with the Seismac program
 * 1) Students will use the slinkys to explore the basic movement of S and P waves.

2. Students will use a laptop with the Program SiesMac to comprehend the effects of distance and intensity of an earthquake. -Have students gently hit the table with their hand near the computer while watching the screen. -Which graph moves? How do you move the other graphs? -Have students experiment by moving the table or gently hitting it to figure out how the movements of each feed on the graph react. - Does how far away from the laptop you hit the table affect how strong the reading is? -Why might it be important to keep our hitting force constant while testing? - Earthquakes can occur at different depths in the Earth's crust. How might we model this to explore how depth affects intensity of earthquakes? In this activity we are going to use textbooks. Stack the textbooks under the computer to simulate different depths within the crust. -Does the number of textbooks under the laptop make a difference, how so? - Based on your observations, how did the amplitude (thickness) if the waves change the further away you hit the table relative to the laptop? Did the number of books also make a difference in the intensity registered on the graphs? What might this say about where an earthquake occurs and the strength of the effects that are felt? How far away can you feel an earthquake? On the other side of the earth can it be detected? (Show the earthquake activity map) **Explanation:** worked in within the lesson. **Elaboration:** (~5min) 3. Have students connect their discoveries with the properties of the layers of the earth. What do you know about the layers of the inside of the earth? Are they solid, moving, thick, thin, hot, cold? - How do we know that there are different layers? Are we able to see them? If we cannot see the interior of the Earth, how might we figure out what is there? Can you think of any ways we are able to see something we can't see with our eyes? - When an earthquake occurs, seismographs all over the earth are usually able to register some sort of waves as a result, however there are holes or shadows were no data is able to be collected. What might cause this? Think about what you know about the layers of the Earth, and what you have just learned about S and P waves. Are there any layers of the Earth that might interfere with either the S or P waves getting through? Why might that be? **Evaluation:** (2-3min) Have a mini group quiz. Ask each student in the group one of each of the following questions one at a time. Ask one other student if they agree with the answer. If the two students do not agree have the group discuss the question and decide on an answer.
 * 1) Give the students a map of North America. If an earthquake were to occur in California, United States would a seismograph in Utah or in Ohio detect the earthquake first?
 * 2) Which wave type would be detected first and why?
 * 3) Describe the motion of each wave as it travels?