When are surface waves generally formed?

Correct answer: When body waves reach near Earth’s surface and spread along it

Surface waves develop when seismic energy reaches the near-surface region and propagates along Earth’s surface. They include Love and Rayleigh waves and often produce strong, damaging ground motion because their energy is concentrated near the surface. P-waves and S-waves are body waves that travel through Earth’s interior; they may help generate surface waves near the surface, but their ordinary passage through the interior is not itself the definition of a surface wave.