Question

what are surface or L waves

Answer 1

Rayleigh waves, also called ground roll, are surface waves that travel as ripples with motions that are similar to those of waves on the surface of water (note, however, that the associated particle motion at shallow depths is retrograde, and that the restoring force in Rayleigh and in other seismic waves is elastic,

Answer 2

L wave : an earthquake wave that travels around the earth's surface and is usually the third conspicuous wave to reach a seismograph.