SEISMIC WAVES & THEIR ROLE IN EARTHQUAKES
The pressure buildup at the fault line from tectonic plate collision is a type of a shockwave that is properly known as a seismic wave. Seismic waves can travel along the Earth's surface (these waves are known as surface waves), or inside the core itself (hence the term body wave). As these waves travel and hit the surface they shake the ground, resulting in an Earthquake. Surface waves have larger amplitudes and last longer than body waves and so they are considered to be more destructive.
THE TWO TYPES OF BODY WAVES
Body Waves travel in curved routes because of the Earth's different geological features and refract accordingly. Some of these features include the different materials in the Earth's core, as well as the state of of the Earth's interior, in particular the liquid interior of the Earth.
Primary Waves (P-Waves)
Primary waves are longitudinal waves, meaning they travel in compressions and rarefactions and have vibrations in the direction of motion. P-waves travel at speeds much higher than those of S-waves. Primary waves can travel through both solids and liquids.
Secondary Waves (S-Waves)
Secondary waves are transverse waves, meaning they travel in motions that form crests and troughs from an equilibrium point that are perpendicular to the direction of motion. As mentioned above, S-waves are slower than P-waves and they only travel in solids. An interesting development from this property of S-waves is that now geologists believe there is a layer of liquid in the Earth's outer core that prevents S-waves from reaching all of the areas P-waves are able to reach.
Primary Waves (P-Waves)
Primary waves are longitudinal waves, meaning they travel in compressions and rarefactions and have vibrations in the direction of motion. P-waves travel at speeds much higher than those of S-waves. Primary waves can travel through both solids and liquids.
Secondary Waves (S-Waves)
Secondary waves are transverse waves, meaning they travel in motions that form crests and troughs from an equilibrium point that are perpendicular to the direction of motion. As mentioned above, S-waves are slower than P-waves and they only travel in solids. An interesting development from this property of S-waves is that now geologists believe there is a layer of liquid in the Earth's outer core that prevents S-waves from reaching all of the areas P-waves are able to reach.