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. People who are outdoors during a major earthquake commonly see Rayleigh waves moving across the surface of the earth, and can feel the ground rising and falling as the waves pass beneath them.
Love waves, sometimes called L-waves, are named after Augustus Love, an English mathematician and physicist who first modeled them mathematically. Love waves involve the surface shearing sideways and then returning to its original form as each wave passes. Skip to main content.
Search for:. Another name for it is the hypocenter. The epicenter is not where the earthquake originated. Earthquakes originate within the earth. The epicenter is the point on the surface of the earth directly above where the earthquake originated. Body Waves There are two types of body waves: P-waves and S-waves.
The speed at which P-waves travel through material is determined by: rigidity—how strongly the material resists being bent sideways and is able to straighten itself out once the shearing force has passed — the more rigid the material, the faster the P-waves compressibility—how much the material can be compressed into a smaller volume and then recover its previous volume once the compressing force has passed; the more compressible the material, the faster the P-waves density—how much mass the material contains in a unit of volume; the greater the density of the material, the slower the P-waves The animations below show P-waves propogating across a plane left and from a point source right.
The speed at which S-waves travel through material is determined only by: rigidity — how strongly the material resists being bent sideways and is able to straighten itself out once the shearing force has passed — the more rigid the material, the faster the S-waves density — how much mass the material contains in a unit of volume — the greater the density of the material, the slower the S-waves The animations below show S-waves propogating across a plane left and from a point source right.
Go to full glossary Add 0 items to collection. Download 0 items. Twitter Pinterest Facebook Instagram. Email Us. See our newsletters here. Would you like to take a short survey? This survey will open in a new tab and you can fill it out after your visit to the site. The moment magnitude scale measures the total energy released by an earthquake. Moment magnitude is calculated from the area of the fault that is ruptured and the distance the ground moved along the fault.
The Richter scale and the moment magnitude scale are logarithmic. The amplitude of the largest wave increases ten times from one integer to the next.
An increase in one integer means that thirty times more energy was released. These two scales often give very similar measurements. How does the amplitude of the largest seismic wave of a magnitude 5 earthquake compare with the largest wave of a magnitude 4 earthquake?
How does it compare with a magnitude 3 quake? The amplitude of the largest seismic wave of a magnitude 5 quake is 10 times that of a magnitude 4 quake and times that of a magnitude 3 quake.
Each scale has their benefits. As mentioned above, the Mercalli Intensity scale is based on how much damage someone would see. This is relative though because some places have strong building codes, and the rock material underneath will impact ground shaking without changing the energy released at the focus. With the Richter scale, a single sharp jolt measures higher than a very long intense earthquake that releases more energy. The moment magnitude scale more accurately reflects the energy released and the damage caused.
0コメント