Consider the following statements with reference to Secondary waves (S-Waves) generated during an earthquake : 1. They create troughs and crests in the material through which they pass. 2. The direction of vibrations of S-waves is perpendicular to the wave direction in the vertical plane. Which of the statements given above is/are correct?

S-waves (Secondary or shear waves) are transverse waves in which particle vibration is perpendicular to the direction of wave propagation. The crest-and-trough pattern is the characteristic of transverse waves, but in seismology this description is more commonly associated with surface waves (like Love and Rayleigh waves) that create wave-like deformation on the surface. S-waves vibrate the material perpendicular to the direction of propagation in the vertical plane, which is correctly captured in statement 2. Statement 1 is incorrect because the trough/crest description applies to surface waves, not body S-waves which cause shearing motion. Therefore only statement 2 is correct.