Ratio of the Earth's core radius to total radius via seismic turning point

In summary, the conversation discusses the observation of S-waves on Earth and the assumption of a perfect sphere. The distance in kilometers is calculated and the need for further steps is mentioned. The diagrams provided show some confusion and lack of understanding, and the ratio of core radius to total Earth radius is mentioned as a calculation to be done.
  • #1
peeballs
13
0
Homework Statement
S-waves are observed to an epicentral distance of about 103 degrees on the Earth (but no further because of the presence of the fluid core). Assuming that the S-wave velocity is constant throughout the mantle (rays are straight lines), compute the ratio of the core radius to the total radius of the Earth (You can ignore the crust).
Relevant Equations
B = sqrt(mu/rho), X(p) = the integral from 0 to turning point of p/(sqrt(u^2-p^2))dz
I've attached a figure I've made; I know I'm to assume the Earth is a perfect sphere in this case. Assuming the 103 degrees is measured as latitude, I've calculated the distance in kilometers (Xp in the second equation above) to be 1.1453e4 km. I know I need u = p at the turning point, but not where to go from here. I'm not convinced this figure is correct, but I'm doing my best.
 

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  • #2
peeballs said:
Homework Statement:: S-waves are observed to an epicentral distance of about 103 degrees on the Earth (but no further because of the presence of the fluid core). Assuming that the S-wave velocity is constant throughout the mantle (rays are straight lines), compute the ratio of the core radius to the total radius of the Earth (You can ignore the crust).
Relevant Equations:: B = sqrt(mu/rho), X(p) = the integral from 0 to turning point of p/(sqrt(u^2-p^2))dz

I've attached a figure I've made; I know I'm to assume the Earth is a perfect sphere in this case. Assuming the 103 degrees is measured as latitude, I've calculated the distance in kilometers (Xp in the second equation above) to be 1.1453e4 km. I know I need u = p at the turning point, but not where to go from here. I'm not convinced this figure is correct, but I'm doing my best.
The top of the upper diagram is cut off, and I do not understand the lower diagram. The angle marked as 103° is clearly less than 90, and there is no basis given for the wider angle where there seems to be a reflection off the core.
From what I can see of the upper diagram, it looks more like what I expected to see, but I've no expertise on this subject, so I could be wrong.
 

1. What is the ratio of the Earth's core radius to total radius?

The ratio of the Earth's core radius to total radius is approximately 0.5, meaning that the core makes up about half of the Earth's total radius.

2. How is the ratio of the Earth's core radius to total radius determined?

This ratio is determined through seismic turning point analysis, which involves studying the travel times of seismic waves as they pass through different layers of the Earth's interior.

3. What is the significance of the ratio of the Earth's core radius to total radius?

This ratio is significant because it provides valuable information about the composition and structure of the Earth's interior, including the size and density of the core.

4. Has the ratio of the Earth's core radius to total radius changed over time?

It is believed that the ratio of the Earth's core radius to total radius has remained relatively constant throughout the Earth's history, with minor changes due to processes such as plate tectonics and mantle convection.

5. Are there any other methods for determining the ratio of the Earth's core radius to total radius?

In addition to seismic turning point analysis, other methods such as gravity and magnetic field measurements can also provide insights into the ratio of the Earth's core radius to total radius.

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