Name: ______________________________________________ Date: _________________ Period: _________________
Inquiry 12.2: Reading a Seismogram
1. Read “The Alaska Earthquake of 1964” on pg. 144 of your textbook and answer these questions:
a. In what location was the seismogram you will be using recorded?
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b. What earthquake did it record?
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c. How many aftershocks did the earthquake have?
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d. What were three results of the earthquake?
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e. How many people died? Why wasn’t this number higher?
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2. Use figure 12.7 on pg. 142 to answer the following questions:
a. What do the numbers 0858 on the seismogram represent?
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b. What does each mark on a line represent?
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c. How long did it take for the seismogram to make one revolution around the drum? How do you know?
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d. When did the first P-wave in the illustration arrive at the station?
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e. When did the first S-wave arrive at the station?
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3. Make observations of your seismogram. How is it like the one in your textbook? How is it different?
Do not make any marks on the seismogram!
4. Find the spot on the seismogram where the main shock of the Alaska earthquake reached Bellingham. How can you
tell where it starts? _______________________________________________________________________________
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5. Using the minute marks at the top of the seismogram, answer the following questions:
a. What time did the seismograph start recording activity? (look at the top of the page).
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b. What kind of clock do seismographs record on? (military or standard?)
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c. What time did the first earthquake wave from the Alaska earthquake reached the seismograph station in
Bellingham, WA? __________________________________________________________________________
d. What wave is this? ________________________________________________________________________
e. What time did the S-wave arrive in Bellingham? _________________________________________________
f.
The earthquake occurred in Prince William Sound, AK at 7:36 PM (19:36 military time). Using the time you
recorded in step C, calculate how long it took the first earthquake wave to reach Bellingham, WA:
i. Earthquake occurred at: _____________________________________________________________
ii. Subtract the time you recorded in C: ____________________________________________________
iii. Equals: Length of time to reach Bellingham. ______________________________________________
g. How fast did the earthquake travel?
i. How far is Bellingham from the Epicenter? _______________________________________________
ii. How fast did the earthquake travel (miles/second)? _______________________________________
6. Look at the bottom ½ of the seismogram. Answer the following questions:
a. Look at the date. What do you think the waves in this bottom half represent?
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b. Find the point on the seismogram that you think represents the first aftershock recorded on March 28.
Record this time. _________________________________________________________________________
c. How many aftershocks do you see altogether? __________________________________________________
Reflecting on What You’ve Done:
1. Do you think seismographs all over the world, or only those near Alaska, were able to record the Alaska earthquake?
Explain.
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2. In what ways might the seismograms recorded in other parts of the world look different from the one recorded in
Bellingham?
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