CE 12.2
Reading a Seismogram
Name ______________________________
Per ______ Date _________________
Reading a Seismogram:
After reading “The Alaska Earthquake of 1964” on page 143 in the Catastrophic Events book,
use figure 12.7 on pg. 142 to answer the questions below about the seismogram in the figure:
1. What do the numbers 0858 on the seismogram represent?
2. What does each mark on a line represent?
3. How long did it take for the seismogram to make one revolution around the drum? How
do you know?
4. When did the first P-wave in the illustration arrive at the station?
5. When did the first S-wave arrive at the station?
Working with your lab group, complete procedure steps 4-13 in the book on page 144. Use the
table below to summarize each step listed. SKIP STEP 12.
Similarities to Fig. 12.7
Differences from Fig. 12.7
Reasoning/Evidence
5.
Observations
Reasoning/Evidence
6.
P-wave arrival time
S-wave arrival time
8.
How long did first EQ wave take to reach Bellingham? (Show calculations)
9.
What do think waves on the bottom half represent?
10.
11.
Time of first aftershock: _________
Number of aftershocks: ___________
Continued on Back 
Reflecting on What You’ve Done
1. At what time did the first earthquake wave (P-wave) reach Bellingham, WA?
2. If the Alaska earthquake began at 7:36pm (19:36 military time) how long did it take for
the first earthquake wave to go from Prince William Sound, Alaska, to Bellingham?
3. How do the aftershocks compare with the first earthquake, or main shock waves,
recorded on the seismogram?
4. Do you think seismographs all over the world, or only those near Alaska were able to
record the Alaska earthquake? Explain your answer.
5. In what ways might the seismograms recorded in other parts of the world look different
from the one in Bellingham?
6. What is one specific question you or your lab group had about this seismogram, that
couldn’t be determined by the information given on the figure or from your background
knowledge?