GEOLOGY

Detailed explanation-1: -P waves travel more quickly than S waves and are always detected first. The aver-age speed of P waves in the Earth’s crust is 6.1 km/s.

Detailed explanation-2: -7) If you are asked to determine the arrival time of the P-wave and given a clock time for the arrival of the S-wave: Find difference in arrival time between P-wave and S-wave at the given epicenter distance, Subtract the difference in arrival time from the clock time of the S-wave.

Detailed explanation-3: -The velocity of a P wave can be expressed as: Velocity P wave = ((B + 1.3G)/Density)1/2, where: B = the bulk modulus-the resistance to change in volume. G = the Shear modulus-the resistance to change in shape.

Detailed explanation-4: -P-waves are the first waves to arrive on a complete record of ground shaking because they travel the fastest (their name derives from this fact-P is an abbreviation for primary, first wave to arrive). They typically travel at speeds between  1 and  14 km/sec.