As a seismologist with extensive experience in the study of seismic waves, I can provide you with a detailed explanation regarding the propagation speeds of P-waves and S-waves.
P-waves, also known as primary waves, are the fastest traveling waves in an earthquake. They are longitudinal waves that move in the same direction as their propagation, causing particles in the Earth's crust to compress and expand as they pass through. This is why they are sometimes referred to as compression waves.
On the other hand, S-waves, or secondary waves, are slower and follow the P-waves. S-waves are transverse waves, which means they move particles perpendicular to the direction of wave propagation. They are not able to travel through liquids, which is why they do not propagate through the Earth's liquid outer core.
The speed difference between P-waves and S-waves is crucial in seismology because it allows us to determine the distance to the earthquake's epicenter. The time it takes for the P-waves to reach a seismograph is compared with the time it takes for the S-waves to arrive, and this time difference can be used to estimate the distance.
To answer your question directly, P-waves travel faster than S-waves. On average, P-waves travel about 60% faster than S-waves. This is because the Earth's interior responds differently to the two types of waves. The ability of P-waves to compress and expand materials allows them to travel through both solid and liquid mediums, whereas S-waves, which move particles side to side, can only travel through solids.
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