Lab%204-5:%20Finding%20Epicenters

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Lab 4-5 Finding Epicenters
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23300
23530
000230
23530 23300
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23510
23920
000410
23920 23510
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23210
23400
000150
23400 23210
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Lets put the lab on pause for now
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How to use the P S

• Wave Chart

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• We dont know when the EQ started.
• But we know how much time there was between the
  PS wave arrivals.
• Lets say 00400
• Cmon lets say it!

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• We have to find a spot on the graph where PS
  (careful!) are separated by 400.

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• Then drop straight down to see the distance to
  the epicenter.

2,600km
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• Now that we know the EQ was 2,600km away, when
  did it start?

To travel 2,600km, a P-wave
needs 500 minutes
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Back to the lab

• The difference in arrival time for Chicago is
  00230.
• That means that Chicago is ______ km from the
  epicenter.

1,400
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• Now that we know the EQ was 1,400km away, when
  did it start?

To travel 1,400km, a P-wave
needs 300 minutes
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• If the P-wave was detected at 23300 and needed
  300 minutes to travel it must have started at

23300 -300 23000
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1,400km
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The EQ happened somewhere on this line
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• Now work on the rest of the lab.