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Author Question: You have collected data on seismic-wave velocities in rocks that exist a few hundred meters below ... (Read 120 times)

P68T

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on: Jul 16, 2018
You have collected data on seismic-wave velocities in rocks that exist a few hundred meters below the surface.
 
  Use information in Figure 8.18 to determine what kind of rock(s) is suggested by these P-wave velocities: 2.25 km/s; 4 km/s; 6.25 km/s; 6.75 km/s; 8 km/s.
  What will be an ideal response?

Question 2

How do we know that P and S waves do not travel through Earth at constant velocities?
 
  What will be an ideal response?


raenoj

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Reply #1 on: Jul 16, 2018
Answer to Question 1

2.25 km/s = unconsolidated sediment or sandstone or limestone
4 km/s = sandstone or limestone
6.25 km/s = granite
6.75 km/s = basalt or lower continental-crust metamorphic rocks
8 km/s = peridotite

Answer to Question 2

Real P and S wave travel times from decades of earthquake records do not match the travel times you would predict based on the assumption that P and S wave velocities are constant throughout Earth. The P and S waves arrive sooner than predicted.


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P68T

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Reply #2 on: Jul 16, 2018
Correct answers!


raenoj

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Reply #3 on: Jul 16, 2018
Great! Please up vote :D


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