LESSON: YOU DON'T NEED A SEISMOGRAPH TO STUDY EARTHQUAKES
Background, Activities and Critical Analysis

By Kevin F. Corrigan Frederick Douglass Charter High School Boston, MA

Subjects: Earth Science, Physical Science, Integrated Science

Time: Two or more class periods (depending on amount of Internet exploration)

Lesson Objectives:

• Students will simulate p waves (longitudinal) & s waves (transverse) using a slinky
  and rope.
• Students will simulate one of the three types of lithospheric boundaries.
• Students will investigate plate tectonics at some select Web sites.

Overview:
Earthquakes are difficult to predict. Most of our scientific investigation occurs after the event. Increasingly, scientists are discovering ways to predict and prevent loss of life associated with these phenomena. This lesson will help students to understand earthquakes.

Much information can be gathered from various Web sites. Among the best of these is the U.S. Geological Survey which is referenced in the activities to follow. The most recent major earthquake, claiming many thousands of lives, occurred in Iran recently. Many places like Iran have a higher probability of quake activity. This is due to plate tectonics. See the Online Newshour story Deadly Tremor in Iran, which shows a picture of the plates in that part of the world.

Here in the United States, we look to the Western part of our country to see the greatest seismic activity. In fact, literally thousands of tiny earthquakes occur in the California and Nevada region each year. The biggest, however, have historically been associated with the famed San Andreas Fault.

Materials

• Vocabulary Terms (have students read over before beginning activities)
• Internet access
• Slinky
• 10 - 12 ft. length of rope
• Styrofoam rectangular blocks (obtain & save from packing materials)
• Toothpicks and glue (or similar small & brittle material)
• Enthusiastic participants!
  

Correlation to National Standards

ACTIVITY #1: Online Investigation - Exploring Major Earthquakes of the Recent Past (This activity can be done in groups or by individual students.)

Procedure:
1. Break students into groups of four. Each group is responsible for one of the four articles below.
2. Have each group read an article and answer the questions that follow.
3. Have students report back about what they find.

Online NewsHour: Deadly Tremor In Iran, December 26, 2003
1. What was the magnitude of this earthquake?
2. How many tectonic plates intersect in Iran? Name them.
3. Describe how these plates interact?
4. Explain why Iran experienced almost 80 times more deaths in the 20th Century than California, despite having the same seismicity.
5. Why would the city of Bam, based on its type of construction, be prone to such devastation?

Online NewsHour: The Seattle Earthquake, February 28, 2001
1. What was the magnitude of this earthquake?
2. How far below the surface was the focus of this earthquake?
3. By referencing subduction, convergence, and the Juan de Fuca Plate, describe the mechanics of this particular earthquake.
4. How far away was this earthquake felt?
5. Why are aftershocks less likely in this type of earthquake?
6. Describe liquefaction as it relates to earthquakes.

Online NewsHour: Earthquake In Turkey, August 17, 1999
1. Why was the timing of this particular earthquake so bad?
2. Where was the earthquake centered? Name some major places impacted.
3. What two major plates impact the Mediterranean?
4. How is Turkey specifically impacted by plate tectonics?
5. Describe how construction in Turkey adds to the potential problem of destruction.

Online NewsHour: Killer Wave, July 20, 1998
1. Describe how this tsunami was triggered?
2. How powerful was the tsunami? Describe the devastation.
3. Describe the mechanics of a tidal wave of this nature. What is the origin of the
word tsunami?
4. What ocean tends to experience more of these tidal waves? Why do you think?
5. What are some other causes of a tsunami? Give an example or two.

ACTIVITY #2 - Investigating Mechanical Waves of an Earthquake

Materials

• Slinky
• 10 - 12 ft. length of rope

Procedure:
1. Simulate the waves of an earthquake using a slinky and a rope:

a. Have a student hold one end of your slinky extended along a lab table. Try to position yourselves so that everyone can see the demonstration.
b. Produce waves along the slinky so that compressions travel toward the student.
c. Invite others volunteers. Better still, have more than one slinky to maximize participation.
d. Explain to students that this is known as a "p" wave or primary wave. It is the first wave that extends in all directions from an earthquake. It is also known as a longitudinal or compression wave.
e. Take the rope, and with another student volunteer, make a series of up and down waves. Be sure to have the student hold it firmly. If he/she also produces waves, it can be confusing because you get interference.
f. Allow other students to participate or supply multiple ropes.
g. Explain to the students that this is known as the "s" wave or secondary wave. It follows behind the "p" wave because it is slower. It shakes the ground up and down as well as back and forth. This type of wave is also known as a transverse wave.

2. Direct students to http://www.usgs.gov/education. Find "Explorers," "Special Topics," "Natural Hazards," "Earthquakes." At the bottom of the page, students can do three separate activities. Choose one for each student or group:

• Earthquakes
• USGS Hazards Program
• Earthquakes for Kids & Grownups (This one is a lot of fun! I particularly recommend to teachers the
  "Earthquake Image Glossary," to expand on student vocabulary.)

3. Direct students to http://quake.wr.usgs.gov/. Find "Real Time Earthquake Maps." At this site students can access the most recent seismic activity for the region of your choice or theirs. Suggestion - Pick "California Nevada" (but you have choices), find "Maps of Recent Earthquake Activity" & "Alphabetical Index of California-Nevada Faults"

4. Have students report, possibly by mapping, on the faults that have experienced the highest levels of recent activity. Note: To get the map without the earthquakes plotted, simply click on remove earthquakes from this map and print it. You may have your own idea for providing a map. For example, I have a dozen sturdy erasable white board maps in my own class.

ACTIVITY #3 - Simulating Lithospheric Boundaries

Materials:

• Styrofoam rectangular blocks (obtain & save from packing materials)
• Toothpicks and glue (or similar small & brittle material)

Procedure:

1. Simulate a Transform boundary

a. Have students use toothpicks and glue to build a post and beam fence. Ask them to construct the fence perpendicular to the two adjoined styrofoam pieces. The Styrofoam can even be lightly glued together
b. After inspecting their construction, have them push against one piece of Styrofoam longitudinally, while holding the other firmly. (I even like to be as specific as to instruct them to push with the left hand away from you while holding firmly in place with the right)
c. Students will note that the fence is broken and misaligned slightly. You want to instruct students to only move the Styrofoam until the friction is overcome such that displacement is a few centimeters.

2. Explain to students that we have just simulated what is known as a transform boundary. The San Andreas Fault is part of such a boundary involving the Pacific Plate and the North American Plate. In the activity just performed, pushing with the left hand represents the movement of the Pacific Plate against the North American Plate.

Student Extension Activity

1. Students are now generally eager and ready to do some more Web site exploration. Instruct them to type in San Andreas Fault in their favorite search engine. Look for USGS and the URL http://pubs.usgs.gov/gip/earthq3/what.html.

2. Students, after reading this page, use either your hands or two books to simulate what type of movement it describes. Do this for members of your class and draw a diagram for your teacher. Be sure to give your objects (ie; books) proper names. Also, the activity performed simulates a scene that can be directly observed at the
Point Reyes National Seashore trail system just North of San Francisco.

For those not able to travel there (I have and I highly recommend it), go to the URL http://pubs.usgs.gov/gip/earthq3/along2.html. This picture shows an event preserved from the 1906 earthquake.

Questions:
1. How does this picture relate to Activity #2?
2. Can you write your own explanation for what you see in the picture?

For Further Investigation: Students can be encouraged to look for maps of the major lithospheric plates. Ask them to explore the difference between a convergent and divergent boundary. Which is associated with ocean floor spreading vs. mountain building? Go back to the first URL in this extension.

Correlation to National Science Standards:

Physical Science - 9-12, Standard B
Conservation of Energy and the Increase in Disorder

• All energy can be considered to be either kinetic energy, which is the energy of
  motion; potential energy, which depends on relative position . . .
  Interaction of Energy and Matter
• Waves, including sound and seismic waves, waves on water, and light waves, have
  energy and can transfer energy when they interact with matter

Earth and Space Science - 9-12, Standard D
Energy in the Earth System

• The outward transfer of earth's internal heat drives convection circulation in the
  mantle that propels the plates comprising earth's surface across the face of the
  globe

Science in Personal and Social Perspective - 9-12, Standard F
Environmental Quality Natural and Human-Induced Hazards

• Normal adjustments of earth may be hazardous for humans. Humans live at the
  interface between the atmosphere driven by solar energy and the upper mantle
  where convection creates changes in the earth's crust. As societies have grown,
  become stable, and come to value aspects of the environment, vulnerability to
  natural processes has increased.

Kevin Corrigan is a veteran science teacher of thirty years. He has taught in California and North Carolina. However, it is Massachusetts where he has spent the majority of his career. As a strong advocate of the integrated and inquiry approaches, Kevin is currently helping to build a science program for the newly formed Frederick Douglass High School in Roslindale, MA. He was recognized by PBS Nova as the "Featured Teacher" for the Fall of 2003. He can be contacted at kfcorrig@yahoo.com

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