Download Activity 43

IAES Plate Tectonics: Activity 43 “Measuring Earthquakes”
Absent Work
Key Words: Richter scale, Seismograph, Seismogram
Getting Started:
1. The U.S. Geological Survey describes an earthquake as follows:
“Generally, during an earthquake you first will feel a swaying or small jerking motion, then a slight
pause, followed by a more intense rolling or jerking motion. The duration of the shaking you feel
depends on the earthquake’s magnitude, your distance from the epicenter, and the geology of the
ground under your feet.”
2. Read the Introduction and Challenge to Activity 43, “Measuring Earthquakes,” in your Student Book
on page D-31.
Procedure:
1. Read Procedure Steps 1-10 on pages D-32 through D-34. Your classmates performed this
experiment.
2. Watch the video link below to see the experiment being performed. Record your observations in the
space provided below.
http://www.youtube.com/watch?v=REr2nV_5TvU
Data:
Follow-Up:
1. Look at Transparency 43.1, “Earthquake Strength,” attached to this packet. Notice that there are
different ways of measuring the strength of an earthquake. One approach is quantitative and the other
is qualitative. The Richter scale quantitatively rates the strength or magnitude of an earthquake at
the point where the rocks break. The Mercalli scale qualitatively rates the damage done, or intensity,
of the earthquake at a particular place on the surface. Each increase of 1 on the Richter scale is equal
to a 30-fold increase of released energy.
2. Did your seismograms provide you with enough information to compare the strength of your
“earthquakes?”
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3. How can modeling earthquakes help you understand plate tectonics?
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Analysis Questions:
1. What similarities and differences did you observe among the 8 seismograms?
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2. a. What did each half of the seismograph model represent?
b. What did the toothpick represent? (Hint: Reread the introduction to this activity.)
c. When did an “earthquake” occur? It occurred when:
 the Data Recorder began pulling the paper tray.
 Plate B was first pushed.
 the toothpick broke.
d. What type of plate movement did you simulate?
 plates colliding
 plates sliding past each other
 plates pulling apart
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3. Describe what the seismogram looked like:
a. when there was little or no movement.
b. when the toothpick broke.
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4. This activity modeled an earthquake occurring along a plate boundary. What do you think are the
strengths and weaknesses of this model?
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