What are seismic waves, and what are the types?
A seismic wave is a wave that travels through the Earth, often as the result of an earthquake or explosion. Seismic waves are studied by seismologists, and measured by a seismograph. Body waves: travel through the interior of the Earth. They follow curved paths because of the varying density and composition of the Earth’s interior. This effect is similar to the refraction of light waves. Body waves transmit the preliminary tremors of an earthquake but have little destructive effect. Body waves are divided into two types: primary (P) and secondary (S) waves. P waves: longitudinal or compressional waves, which means that the ground is alternately compressed and dilated in the direction of propagation. These waves generally travel twice as fast as S waves and can travel through any type of material. Typical speeds are 330m/s in air, 1450m/s in water and about 5000m/s in granite. S waves: transverse or shear waves, which means that the ground is displaced perpendicularly to the direction o
