EVERYDAY SCIENCE

Detailed explanation-1: -P waves are the first waves that are detected by a seismograph. They are the fastest seismic waves and can travel through gases, liquids, or solids.

Detailed explanation-2: -P waves travel fastest and are the first to arrive from the earthquake. In S or shear waves, rock oscillates perpendicular to the direction of wave propagation. In rock, S waves generally travel about 60% the speed of P waves, and the S wave always arrives after the P wave.

Detailed explanation-3: -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.

Detailed explanation-4: -Generally, p-wave velocity increases with depth and increases with increasing rigidity of a material. Therefore p-waves travel fastest through the solid, iron inner core of Earth.

Detailed explanation-5: -P waves, or primary waves, arrive first while S waves, or secondary waves, arrive second. Both waves cause the ground to shake when an earthquake occurs.