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Abstract

  • This activity will educate students about earthquakes and vibrations using a shake table and the Quake Catcher Network (QCN) device.
  • This experiment asks students to graph data for the interpretation and study of earthquakes.
  • Shake tables are useful tools for testing structures. By simulating earthquake shaking, we can better design buildings and learn from their failures.

Introduction

K-12 Earthquake Activity Teaching Modules

A Joint Project of the Network for Earthquake Engineering Simulation (NEES) and the Southern California Earthquake Center (SCEC)

In the spring of 2011, NEES at the University of California Santa Barbara (NEES@UCSB) embarked on a project to develop a comprehensive set of teaching modules for K-12 students that would cover the basics of plate tectonics and earthquake dynamics. The idea for the project grew from the success of the “Make Your Own Earthquake” outreach activity developed by NEES@UCSB, which recently has included the use of the Quake Catcher Network MEMS accelerometer.

The UCSB site received a supplemental grant for Education, Outreach, and Training from NEES that provided funds for an undergraduate student to work on this project. Two NEES REU interns and a SCEC intern were also recruited, for a total of four students working cooperatively on the project over the summer of 2011. NEES@UCSB personnel served as mentors to the students and a Santa Barbara GATE science teacher was hired, through the NEES EOT grant, as a consultant to review the work. The students were asked to incorporate, as appropriate, the use of the QCN accelerometer and real earthquake data in the teaching modules. They were also asked to do a comprehensive survey of earthquake-related teaching materials currently available and to incorporate, with proper references, any of these materials into the new modules.

Over the course of the summer of 2011, the students met weekly with their mentor and the science teacher. In August, a group of local 4th – 6th grade students came to the UCSB campus and tested several of the earthquake activities. The summer interns presented their work at the NEES REU Young Researchers Symposium at UCSB in August and at the annual SCEC meeting in Palm Springs in September.

The 12 earthquake activity modules are summarized below:

Personnel:

Jamison Steidl, Ph.D., Principal Investigator, NEES@UCSBSandra Seale, Ph.D., Project Scientist and Outreach Coordinator, NEES@UCSBCarrie Garner, M.A., Gifted and Talented Education Teacher and Coordinator, Hope School District

Summer Undergraduate Interns:

Sean Allen, Civil Engineering, University of Nevada, RenoHeidi Pence, Civil Engineering, University of MichiganJoseph Trudeau, Geology, University of WisconsinHanna Vincent, Mechanical Engineering and Materials, MIT

Earthquake Activity Modules:

9th – 12th Grade: Shake Table, Joseph Trudeau and Hanna Vincent

[Be sure to click the "Docs and Attachments" tab to view and download attachments for this lesson such as handouts and worksheets.]

Learning Objectives and Standards

Links to the National Science Standards and to individual State Science Standards are available by using this link:

http://nees.org/education/for-teachers/k12-teachers#standards

Investigation and Experimentation

1. Scientific progress requires researchers to ask meaningful questions and conduct careful investigations. As a basis for understanding this concept and addressing the content in the other four strands, students should develop their own questions and perform investigations. Students will:

a. Select and use appropriate tools and technology (such as computer-linked probes, spreadsheets, and graphing calculators) to perform tests, collect data, analyze relationships, and display data.

b. Identify and communicate sources of unavoidable experimental error.

c. Identify possible reasons for inconsistent results, such as sources of error or uncontrolled conditions.

d. Formulate explanations by using logic and evidence.

g. Recognize the usefulness and limitations of models and theories as scientific representations of reality.

j. Recognize the issues of statistical variability and the need for controlled tests.

4. Waves have characteristic properties that do not depend on the type of wave. As a basis for understanding this concept:

a. Students know waves carry energy from one place to another.

b. Students know how to identify transverse and longitudinal waves in mechanical media, such as springs and ropes, and on the earth (seismic waves).

California state standards satisfied:

Dynamic Earth Processes

3. Plate tectonics operating over geologic time has changed the patterns of land, sea, and mountains on Earth’s surface. As the basis for understanding this concept:

d. Students know why and how earthquakes occur and the scales used to measure their intensity and magnitude.

California Geology

9. The geology of California underlies the state’s wealth of natural resources as well as its natural hazards. As a basis for understanding this concept:

b. Students know the principal natural hazards in different California regions and the geologic basis of those hazards.

Material List

Materials Needed:

  • Saw: A circular saw works best.
  • Drill: With varying size drill bits.
  • 2 sheets of 1/2in plywood 23” x 47”.
  • 1" wood screws (20 total).
  • Twine.
  • 4 small bungee cords.
  • 1 screw eye.
  • 400-piece K'nex Value Tube.
  • Graph paper for each student.
  • Quake Catcher Network (QCN) Device available at http://qcn.stanford.edu/learning/requests.php#Purchase
    • The device plugs into a USB port on any computer and the program to run it is available at http://qcn.stanford.edu/downloads/
    • The QCN device is $5 to purchase or free for underserved schools.
  • Computer to attach the QCN device and run the program.
    • Optional: Excel software for maintaining a spreadsheet of the experiment results.

Procedure

Set Up:

  1. Cut 3 boards to 12” x 19”. These will be the three sides of the box. One side remains open for access to the strings that cause the shaking.
  2. Cut 1 board to 19” x 19.5". This is the bottom of the box.
  3. Attach the sides to the bottom board using 1” screws to make an open-sided box.
  4. Cut the last board to 17” x 17”. This is the platform (base board) that gets shaken.
  5. Drill a hole in the exact center of the platform. Thread a line through this hole and make a knot on the top side of the platform. This line will control the z-axis (vertical) shaking. See photo, below.
  6. Drill holes in the platform ½” x ½” from the corners.Shake_It_Up_Figure_1
  7. Screw in a screw eye into the exact center of the bottom. The line that you just attached to the platform board will be fed through this eye to control the z-axis.
  8. Drill holes in the two of the side boards that are parallel to each other. The holes should be 1” x 1” from the top corners so there are 4 total.
  9. Choose a side of the platform and drill a hole in the platform board at the center of the side and ½” from the edge. Thread a line through this hole and make a knot on the bottom side.
  10. Repeat step 9 for one of the sides adjacent to the one you chose in step 9. See photo, above.
  11. Attach one end of the bungee cords in the 4 holes drilled in the side boards and pull the other end through the corner holes in the platform. Tie a knot in the cords under the platform. Pull them somewhat taught so that the board is suspended by the bungees, but still has some spring to it. Make sure that the sides with the holes drilled in steps 9 and 10 are not facing the open side of the box. Make sure that the board is level. Once the platform is level, secure the bungee cords by tying a knot in them on the side.
  12. Now drill holes in the two sides of the box that face the sides with the holes drilled in steps 9 and 10. The holes should be drilled to be at the same level as the top of the platform, at the center of the side and ½” from the edge. See pictures, below.Shake_It_Up_Figure_2 Shake_It_Up_Figure_3
  13. Thread the lines from the holes drilled in the sides of the platform through the outside holes in the sides of the box. These lines will be used to control the horizontal shaking.Shake_It_Up_Figure_4 Shake_It_Up_Figure_5

Links and Resources

Vocabulary:

Amplitude (wave): The height of the largest pulse in a wave between its minimum and maximum.

Dependent Variable: The variable being studied and expected to change with the independent variable. It is dependent on the independent variable. It answers the question of what is being observed.

Epicenter: The point on the Earth’s surface above the focus hypocenter.

Fault: A planar break in the rock, along which an earthquake can occur.

Focus or hypocenter: The point below the surface at which an earthquake occurs.

Hypothesis: Derived from the Greek word hypotithenai meaning "to suppose" or "to put under." A hypothesis is a proposed explanation for an observed phenomenon.

Independent Variable: Variable being tested or changed.

Kinetic Energy: The energy an object has due to its motion. A ball on the edge of a table has potential energy. A ball falling off the table has kinetic energy.

Lithosphere: The rigid outermost layer of the earth.

Liquefaction: The process of sand and soil behaving like a dense liquid rather than a solid during an earthquake. Water flows between the pores in the soil to cause this natural phenomenon.

Magnitude: A measure of the size of an earthquake. For every unit magnitude increase, the energy output is about 32 times greater. For an earthquake of M5.5 and another of M6.5, the M6.5 had 32 times the energy released than the M5.5 earthquake.

P and S Waves: Also known as primary and secondary waves. Body waves generated by an earthquake that arrive before the surface waves. The p (pressure) wave travels faster than the s (shear) wave.

Plate Tectonics: A model of the earth's lithosphere being divided into plates that move millimeters to centimeters a year.

Potential Energy: The energy an object has because of its position. A ball on the edge of a table has potential energy. A ball falling off the table has kinetic energy.

Seismogram: The record of ground motion generated by an earthquake.

Seismogram pendulum: Instrument that swings on a single axis to measure the amplitude of the shaking in that direction during an earthquake.

Seismograph: Instrument that records seismic vibrations.

Seismologist: A person who studies earthquakes and the composition of the Earth's interior.

Seismology: The study of earthquakes and the composition of the Earth's interior.

Surface waves: The waves generated from an earthquake that travel along the surface of the Earth, as opposed to body waves, which travel through the Earth. Surface waves travel along the surface of the earth at a slower speed than the S waves. There are two types of surface waves: Rayleigh waves and Love waves.

Seismometer: Mass and transducer inside the seismograph.

Triangulation: The process of finding the epicenter of an earthquake by comparing the distance of the event computed from the records of 3 different seismograph stations.

Tsunami: A long ocean wave usually caused by sea-floor movements from an earthquake. Undersea landslides can also produce tsunamis, but these are usually smaller in scale. When tsunamis occur, they usually arrive in several waves and the first to hit the shore is not necessarily the largest.

Background:

Earthquakes release energy. For every unit increase in magnitude, the energy output is about 32 times greater. If you compare an earthquake of M5.5 and another of M6.5, the M6.5 had 32 times the energy released than the M5.5 earthquake. The amplitudes of the earthquake waves increase by a factor of 10 for each unit increase in magnitude.

In order to get a complete picture of an earthquake, an instrument needs to record motions on 3 axes. Seismographs have three instruments measuring ground motion in the vertical and two horizontal directions. By studying records recorded over a large area, a seismologist can determine the location and the magnitude of the earthquake.

History:

A few examples of historical large earthquakes in the United States are the 1906 San Francisco Earthquake, the 1989 Loma Prieta Earthquake, and the 1964 Prince William Sound Earthquake in Alaska. These quakes demonstrate that the magnitude of the quake is not the only factor in generating damage.

The 1906 San Francisco Earthquake is still under investigation and the magnitude of the quake is disputed. The moment magnitude (Mw) has been estimated at M8.0 (de Boer and Sanders 2005). The casualty report is also debated and the initial report cited only 375 deaths. More recent estimates give a death toll of 2,500 people in the San Francisco area. The fire damaged more property than the quake itself by a factor of 10 (Bolt 1993), (de Boer and Sanders 2005).

The 1989 Loma Prieta event is also called the World Series Earthquake because it took place during the World Series near San Francisco. The casualties in this quake were 63 dead and almost 4,000 injured (Bolt 1993). There were few casualties in this earthquake because at that time of day (early evening), most people were in their homes. Most homes are constructed of wood, which holds up to earthquakes fairly well. The quake had a surface wave magnitude of M7.1 (Bolt 1993).

The 1964 Prince William Sound event in Alaska had 130 casualties, with only 9 being a direct result of the shaking of the earthquake (Bolt 1993). The rest of the damage came from two secondary affects of earthquakes: tsunamis and liquefaction.

Earthquake Prediction:

Why is it that Southern California is in the news all the time talking about the Big One coming? The answer is a matter of probability. California has a 99.7% chance of having a M6.7 or greater earthquake in the next 30 years. The probabilities are different for different sections of the San Andreas Fault (Figures 10 and 11). The San Andreas Fault is a strike-slip fault on the boundary of the Pacific and North American tectonic plates that is capable of producing these large events.

The Earth’s tectonic plates are always in motion and they move at millimeters to centimeters per year. Faults that are locked allow tectonic stress to build up over time and then release the stress suddenly and violently in an earthquake. Faults that have had a large rupture within the recent geologic past have not had enough time to build up large stresses, so the probability of having another large event is low. Faults that have not had a large event in the recent geologic past have accumulated tectonic stress and therefore have a higher probability of producing a large earthquake. This is the case with the San Andreas Fault, which is the fault most likely to produce a significant earthquake in California. The southern section of the fault has the highest probability of producing a large earthquake because that section of the fault has not produced a significant event in recent history.

Figures:

Shake_It_Up1

Figure 1: Screen shot of the QCN device acceleration data. Units of acceleration are cm/sec/sec.

Shake_It_Up2

Figure 2: Final set up of the shake table with K’nex structure and QCN device.

Shake_It_Up_Figure_7

Figure 7: Mean Max Accelerations at the base and top of the 3-story structure for z-axis input shaking.

Shake_It_Up_Figure_8

Figure 8: Mean Max Accelerations at the base and top of the 3-story structure for y-axis input shaking.

Shake_It_Up_Figure_9

Figure 9: Mean Max Accelerations at the base and top of the 3-story structure for x-axis input shaking.

UCERF: Map of California Area Earthquake Probabilities

Shake_It_Up_Figure_10

Figure 10. "The colors on this California map represent the UCERF probabilities of having a nearby earthquake rupture (within 3 or 4 miles) of magnitude 6.7 or larger in the next 30 years. As shown in the table, the chance of having such an event somewhere in California exceeds 99%. The 30-year probability of an even more powerful quake of magnitude 7.5 or larger is about 46%. (2007 Working Group on California Earthquake Probabilities (WGCEP 2007))"

UCERF: California Area Earthquake Probabilities, Northern vs. Southern

Shake_It_Up_Figure_11

Figure 11. "The dashed line of this California map is the boundary between northern and southern California used in the UCERF study. As shown in the table, the 30-year probability of an earthquake of magnitude 7.5 or larger is higher in the southern half of the state (37%) than in the northern half (15%). The colors represent the same local probabilities shown in Figure 10. (2007 Working Group on California Earthquake Probabilities (WGCEP 2007))"

Learning modules in this series:

Assessment

Name:________________________

Worksheet:

  1. Build a 3-story structure with the K-nex.
  2. Start by testing your shake table. The QCN device measures acceleration in units of cm/sec/sec.Plug the QCN device into a computer and place it in the center of the platform and pull the three axis lines. Let the QCN device come to rest and then release the lines. This causes shaking. Repeat this experiment and mark on the lines how far back each one has to be pulled to get the desired quake. When you pull the line back, hold it steady and let the QCN come to rest (there will always be background noise). Figure 1 is a screenshot from the QCN device.
  3. Do you think the acceleration recorded by the QCN device attached directly to the shake table will be different compared to one attached to the structure built out of K'nex? Use scientific reasoning to explain your answer.
  4. Place the 3-story structure on the platform and secure its base with tape. Place the QCN device on top of the structure on the shake table and activate only the z-axis (vertical axis). Note the minimum acceleration and the maximum acceleration on each axis (x, y, and z) recorded by the QCN. Write these down in Figure 3 and/or enter in Excel. Repeat this experiment 4 times more. Do the same 5 tests with the x and y axes activated.
  5. Now place the QCN device on the platform (under the structure) and repeat. Write your results in Figure 4. The base sensor is the control for this experiment and you will want to compare your data from the structure to the base sensor.
  6. Calculate the maximum amplitudes of the acceleration pulse in each experiment: amplitude = max acceleration – min acceleration. Write down the results in Figures 3 and 4. See Figures 5 and 6 for examples.
  7. What do you notice about the max amplitudes of acceleration?
  8. For repeated trials of the same experiment, calculate the mean of all amplitudes. See Figures 5 and 6 for examples.
  9. Graph the amplitudes on graph paper (or use Excel) and describe down the trends you see. See Figures 7 - 9 for examples.
  10. You may have noticed that the amplitudes are greater when the QCN device is on the top of the structure. What is a good explanation for this phenomenon? How do you think tall buildings respond to an earthquake?
  11. What are some sources of error in this experiment?
  12. What are some ways to minimize these experimental errors that you just listed?
  13. What are some unavoidable experimental errors?

Scaling

Additional Experiments:

  1. Build a 1- and a 2-story building. Run the same experiments with these structures and compare the maximum accelerations of each structure to the other two as well as to the base sensor.
  2. Design a 2-story structure with no triangular bracing. This will mimic the basic design of a two-story house with the garage on the first floor with the main living quarters on the second floor. Place the QCN device on top of the structure and use either the x or y axis lines to cause an earthquake. Write done the amplitudes and compare them to the amplitudes of the 1- and 2-story buildings.
  3. Design a building with the K’nex that will be stronger in an earthquake than your first design. Write down why you believe your design will be more effective than the original model you made. Test the model, write down your results and compare with the first buildings you tested. What can be done to further make the building more structurally sound?
  4. Design and run an experiment of your own. In this exercise come up with a theory of your own and test this theory using methods that you develop. The goal of this exercise is to better understand the scientific process. It is okay if your experiment doesn't provide the outcome you intended. Write down why it didn't work and propose a possible solution. This experimentation emphasizes unknown variables. Use the scientific process. Describe the experiment in detail. Before testing, run the experiment by your teacher for any suggestions. Use the following questions as a guide.

     

    1. Come up with an experiment to test. What are you trying to answer?
    2. What is your hypothesis?
    3. What is your predicted outcome?
    4. What is the dependent variable and what is the variable being tested?
    5. How will the variable you choose be used to collect information?
    6. Make a chart of the information you collected from the experiment
    7. Graph the data you collected.
    8. Does this data support your prediction? Why or why not?
    9. Write a short report on the experiment talking about your method, hypothesis, results and conclusion.

Cite this work

Researchers should cite this work as follows:

  • Sandra Seale; Joe Paul Trudeau; Hanna Vincent; NEES EOT (2011), "Shake Things Up!," http://nees.org/resources/3923.

    BibTex | EndNote

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