1. Review how to interpret seismographs from the “Rockin’ and Rollin’" lab in your portfolio.
2. Answer the questions on this page. Even though some are multiple choice, please explain how you arrived at your answer.
1. Look carefully over the eight seismograms from the seismic stations around the world.
a) Which location experienced the greatest
shock? How can you tell?
b) Which location is probably closest to
c) Which location is the farthest from
2. A typical earthquake sends out at least
three types of waves: Primary (P), Secondary (S), and Surface (L) waves.
These waves travel differently in the earth and make different patterns
on the seismogram. For example, L waves are normally the last to arrive
(take the longest time), but they also cause the most surface damage to
a) Tokyo received all three types of waves.
Locate on the Tokyo seismogram the beginning of the P waves. How many minutes
did the Tokyo clock read when the first P waves hit Tokyo?
b) How many minutes did the Tokyo clock
read when the first S wave hit Tokyo?
c) How many minutes did the Tokyo clock
read when the first L wave hit Tokyo?
3. Name the four locations that received
all three types of waves (P, S, and L).
4. From the moment the first P wave arrived, the seismogram shows how many minutes passed before the S waves arrived, followed later by the L waves.
a) Which type of wave is the fastest?
b) Which type of wave is the slowest?
c) At which location did the P and S waves
arrive closer together -- San Francisco or Hawaii? What does this tell
you about the location of the epicenter?
5. At some locations, not all of the three waves arrived.
a) Which locations appear to have received
only P and L waves, but no S waves?
b) Which locations appear to have received
only L waves?
6. Some locations that are close to each other did not receive the same waves.
a) Did San Francisco receive a P wave?
Did Los Angeles?
b) Compared to the size of the earth, these
two cities are close to each other.
Why do you think the P wave arrived in one of these cities but not in the other?
Make a good hypothesis to explain this observation.
7. Look at the L waves for Kingston, for Jamaica and for Miami, Florida.
a) Which one -- Kingston or Miami -- is
probably closer to the epicenter?
How can you tell from the seismograms?
b) Did Kingston receive a P wave? did Miami
receive a P wave?
c) These two cities are not very far from
each other on the earth.
Why did the P wave arrive in one of these cities but not in the other?
Make a good hypothesis again. (Remember which city is farther from the epicenter!)
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