GEOLOGY

Detailed explanation-1: -S-waves are transverse waves. Even though they are slower than P-waves, the S-waves move quickly. Typical S-wave propagation speeds are on the order of 1 to 8 km/sec.

Detailed explanation-2: -In the Earth the speed of S waves increases from about 3.4 km (2.1 miles) per second at the surface to 7.2 km (4.5 miles) per second near the boundary of the core, which, being liquid, cannot transmit them; indeed, their observed absence is a compelling argument for the liquid nature of the outer core.

Detailed explanation-3: -P-waves travel fastest, at speeds between 4-8 km/sec (14, 000-28, 000 km/h) in the Earth’s crust.

Detailed explanation-4: -Why do P waves arrive first? When an earthquake occurs, seismic waves, including P and S waves carry energy away from the hypocenter in all directions. The P wave propagates with a velocity of about six kilometers per second in rock, while the S wave is slower at four kilometers per second.