Why do surface waves tend to cause the most damage?

Seismologists have long recognized the destructive power of surface waves, which are a type of seismic wave that travels along the Earth's surface. There are two main types of surface waves: Love waves and Rayleigh waves. Here's why they tend to cause the most damage: 1. Large Amplitude: Surface waves have a larger amplitude compared to body waves (P-waves and S-waves). This means they move the ground more violently, leading to more severe shaking and potential structural damage. 2. Shallow Focus: The energy of surface waves is concentrated near the Earth's surface. This shallow focus means that the destructive effects are felt more directly by buildings and infrastructure, which are not designed to withstand such forces. 3. Slower Speed: While surface waves are slower than P- and S-waves, this slower speed allows the energy to be released over a longer period of time. The longer the shaking lasts, the more opportunity there is for structures to be damaged or collapse. 4. Resonance: Surface waves can cause certain natural frequencies of buildings and other structures to resonate with the frequency of the waves, amplifying the shaking and increasing the likelihood of damage. 5. Ground Conditions: Surface waves are particularly destructive in areas with soft or loose soil, as these materials can amplify the shaking even more. 6. Love Waves: Among surface waves, Love waves are particularly dangerous. They move the ground in a side-to-side motion, which is particularly damaging to structures not designed to withstand such forces. 7. Rayleigh Waves: Rayleigh waves are also highly destructive. They cause both vertical and horizontal movement of the ground, which can lead to widespread damage. In summary, the combination of large amplitude, shallow focus, slower speed, potential for resonance, and the impact of ground conditions make surface waves particularly damaging during earthquakes.

Although they're slower than either P-waves or S-waves, they have large amplitudes, and that full amplitude is focused on the surface of the earth. This is why they cause more damage. Love waves are the most dangerous of all kinds of seismic waves. They are faster than Rayleigh waves and even larger in amplitude.