A) S-wave first followed by R-wave and P-wave
B) L-wave first followed by P-wave and S-wave
C) Body wave first followed by surface wave and S-wave
D) P-wave first followed by S-wave and surface wave
Correct Answer: D
Solution :
[d] P-waves are a type of body wave, called seismic waves in seismology that travel through a continuum and are the first waves from an earthquake to arrive at a seismograph. The continuum is made up of gases (as sound waves), liquids, or solids, including the Earth. The name P-wave can stand for either pressure wave as it is formed from alternating compressions and rarefactions or primary waves as it has the highest velocity and is therefore the first wave to be recorded. S-waves, secondary waves, or shear waves (sometimes called an elastic S-wave) are a type of elastic wave, and are one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves. Its name, S for secondary, comes from the fact that it is the second direct arrival on an earthquake seismogram, after the compressional primary wave, or P-wave, because S-waves travel slower in rock. Unlike the P-wave, the S-wave cannot travel through the molten outer core of the Earth, and this causes a shadow zone for S-waves opposite to where they originate. Surface waves span a wide frequency range, and the period of waves that are most damaging is usually 10 seconds or longer. Surface waves can travel around the globe many times from the largest earthquakes. Surface waves are caused when P waves and S waves come to the surface.
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