7/23/2019 Gelombang Seismik S

1/1

Which seismic waves will not pass through a liquid?

S-waves can travel only through solids, as fluids (liquids and gases) do notsupport shear stresses. S-waves are slower than P-waves, and speeds are typically around 60% of that of P-waves in any given material. Surface waves[edit] Seismic surface waves travel along the Earth's surface.Gases, liquids and solids compress just the same way: the electron shells repeladjacent atoms, while molecular bonds hold them together, and compression waves(seismic P waves) have resistance in moving away from equilibrium, and unbalanced forces pushing them back into equilibrium position. The essence of wave motion is that there is inertia (mass) and restoring forces (springs) acting in concert about the equilibrium points.

Sheer waves have the same thing going in solids; the molecules wiggle to the side, and there are restoring forces bringing them back to center. But in a liquidor a gas, there is no restoring force. As the atoms are moved to the side, theyremain where they come to rest; there is no "spring" to bring them back to wherethey started from.

Light is a wave but it is electromagnetic in nature; it isn't an effect of inertia and springiness in any sort of media; this was and insight that Einstein capitalized on in his theory of special relativity. No "ether" is required to propagate EM waves. Because of that they travel through all media that they are transparent to, including no media at all. At bottom, EM waves are a completely differ

ent phenomena from mechanical waves; they only coincidentally follow a lot of the same rules of motion.S-waves are shear waves, which move particles perpendicularly to their directionof propagation. They can propagate through solid rocks because these rocks haveenough shear strength. The shear strength is one of the forces that hold the rock together, and prevent it from falling into pieces. Liquids do not have the same shear strength: that is why, if you take a glass of water and suddenly removethe glass, the water will not keep its glass shape and will just flow away. Infact, it is just a matter of rigidity: S-waves need a medium rigid enough to propagate. Hence, S-waves do not propagate through liquids.