Answer: Either it's B. The seismic waves frequency also changed multiple times.
or
D. As the wave passed through less dense material, the speed of the wave increased.
Explanation: I'll let you choose because I'm stumped on which one it is. They both sound like they would fit perfectly with the question and I've tried doing research on it but nothing can prove either one right or wrong for me.
I know seismic waves can change frequency given the density of rock\ground it's going through.
"The propagation velocity of seismic waves depends on density and elasticity of the medium as well as the type of wave. Velocity tends to increase with depth through Earth's crust and mantle, but drops sharply going from the mantle to outer core."
However, B. also fits nicely.
"Temperature tends to lower the speed of seismic waves and pressure tends to increase the speed. Pressure increases with depth in Earth because the weight of the rocks above gets larger with increasing depth."
Nevertheless, I hope it helps.
If the speed changes multiple times, the seismic wave's frequency also changed multiple times. Option B is correct.
The distance between two successive troughs or crests is known as the wavelength. The peak of the wave is the highest point, while the trough is the lowest.
The relationship between the wave's wavelength, frequency, and speed is given as
wavelength = speed of wave / frequency
A seismologist who studies earthquakes sees that a seismic wave that traveled 500 km through Earth changed speeds multiple times.
If the speed changes multiple times, the seismic wave's frequency also changed multiple times. Because both area related to each other.
Hence, option B is correct.
To learn more about the wavelength, refer to the link;
brainly.com/question/7143261
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