What is the difference between p waves and s waves

Secondary waves , or S waves, are slower than P waves. The motion of secondary waves is perpendicular to the direction of the wave travel, similar to the motion of vigorously shaking a rope SF Fig. Scientists use seismometers Fig. Seismometers measure the vibrations of the ground, relative to a stationary instrument. Data from a seismometer, also called a seismogram, shows velocity on the y axis and time on the x axis Fig.

Note in SF Fig. SF Table 7. The speed at which seismic waves travel depends on the properties of the material that they are passing through. For example, the denser a material is, the faster a seismic wave travels SF Table 7. P waves can travel through liquid and solids and gases, while S waves only travel through solids.

Scientists use this information to help them determine the structure of Earth. For example, if an earthquake occurs on one side of Earth, seismometers around the globe can measure the resulting S and P waves. Secondary waves travel slower, move in an up-and-down pattern, travel only through solids, and cause more damage due to their greater size.

P waves travel faster than S waves, and are the first waves recorded by a seismograph in the event of a disturbance. P waves travel at speeds between 1 and 14 km per second, while S waves travel significantly slower, between 1 and 8 km per second. The S waves are the second wave to reach a seismic station measuring a disturbance.

The difference in arrival times helps geologists determine the location of the earthquake. Primary waves are made up of compression waves, also known as push-pull waves. The individual waves, therefore, push against one another, causing a constant parallel, straight motion. S waves are transverse waves, which means they vibrate up and down, perpendicular to the motion of the wave as they travel. In an S wave, particles travel up and down and the wave moves forward, like the image of a sine wave.

Because of their wave movement, P waves travel through any kind of material, whether it is a solid, liquid or gas. On the other hand, S waves only move through solids and are stopped by liquids and gases. For this reason, S waves are sometimes referred to as shear waves because they are unable to alter the volume of the material that they pass through.

This also accounts why fewer S waves are recorded than P waves. Vibrations produced by a natural earthquake instead tend to rumble for quite a while. But when that energy reaches the surface, it now can spread as either of two different types of waves.

These waves also are typically larger and cause much more damage than P waves and S waves. The faster of these surface waves was named after British mathematician A. More than years ago, he worked out the math that explains how such waves move. The second type of surface waves were named for a British physicist who, in the s, predicted their existence.

This scientist was named John William Strutt. His father had been a British noble dubbed Lord Rayleigh. The waves he predicted are now known as Rayleigh waves. In other words, for a Love wave traveling north, the ground shakes back and forth from east to west. Rayleigh waves, on the other hand, cause ground movements in two directions at once.

The other is a push-pull movement along the same path that the wave is traveling. Together, those motions generate a rolling action that can cause extreme damage to buildings and other structures.

Geoscientists often use seismic waves to map details of the inner structure of our planet. Those calculations are made possible, in large part, because researchers have measured the speed of seismic waves through rocks under immense pressure in the lab.

In some cases, they also provide strong clues about the type and density of materials in those layers. These include things such as faults and sediment-filled basins. Sediment-filled basins are broad bowls of solid rock where loose material accumulates. Such areas can be especially affected by earthquakes. Again, the time it takes for a seismic wave to travel to a structure and then echo back helps scientists estimate how far away that structure is.

Even people setting off small explosions of dynamite can trigger seismic waves. That means these can be mapped from afar. By Sid Perkins January 12, at am. P versus S waves Seismologists are scientists who study earthquakes.