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Q: Which reference to the interior of the earth consider the following statements : 1. The P–waves are similar to sound waves. They can travel through only solid materials 2. The mean thickness of continental crust is around 30 km 3. The surface waves are the last to report on seismograph Which of the statements given above is/are correct?
  • A. 1 and 3 only
  • B. 2 and 3 only
  • C. 3 only
  • D. 2 only
Correct Answer: Option B - Primary waves (P-waves) are compressional waves that are longitudinal in nature. P waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph.These waves can travel through any type of material, including fluids, and can travel at nearly twice the speed of S waves. Secondary waves (S-waves) are shear waves that are transverse in nature. S-waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses. S-waves are slower than P-waves, and speeds are typically around 60% of that of P-waves in any given material hence last to report on seismograph.
B. Primary waves (P-waves) are compressional waves that are longitudinal in nature. P waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph.These waves can travel through any type of material, including fluids, and can travel at nearly twice the speed of S waves. Secondary waves (S-waves) are shear waves that are transverse in nature. S-waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses. S-waves are slower than P-waves, and speeds are typically around 60% of that of P-waves in any given material hence last to report on seismograph.

Explanations:

Primary waves (P-waves) are compressional waves that are longitudinal in nature. P waves are pressure waves that travel faster than other waves through the earth to arrive at seismograph.These waves can travel through any type of material, including fluids, and can travel at nearly twice the speed of S waves. Secondary waves (S-waves) are shear waves that are transverse in nature. S-waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses. S-waves are slower than P-waves, and speeds are typically around 60% of that of P-waves in any given material hence last to report on seismograph.