Are earthquakes longitudinal or transverse waves?

As a seismologist with extensive experience in the study of seismic waves, I can provide a detailed explanation of the types of waves produced by earthquakes. Earthquakes generate different types of seismic waves, which can be classified into two main categories: body waves and surface waves. Body waves are further divided into two types: P-waves (primary waves) and S-waves (secondary waves). P-waves are longitudinal waves, meaning that the particle motion is in the same direction as the wave propagation. They are the fastest moving waves and are the first to be detected by seismographs after an earthquake occurs. S-waves, on the other hand, are transverse waves, where the particle motion is perpendicular to the direction of wave propagation. They travel more slowly than P-waves and are not able to pass through liquids, which is why they are not present in the Earth's outer core. In addition to P-waves and S-waves, there are also surface waves, which travel along the Earth's surface and cause the most damage during an earthquake. Surface waves include Rayleigh waves, which are similar to ocean waves and have both vertical and horizontal components, and Love waves, which are transverse waves that move in a side-to-side motion along the surface. To summarize, earthquakes produce both longitudinal and transverse waves through their P-waves and S-waves, respectively. Surface waves, which are also significant in earthquake dynamics, include both longitudinal and transverse components.

First of all, Earthquakes are not necessarily transverse waves. Both transverse and longitudinal waves are there in Seismic waves. ... They typically travel up to 60% of the velocity of P-waves. They necessarily require the Shear-modulus of the medium.