Seismic waves are produced by all earthquakes
Earthquake waves are seismic waves that are created when energy builds up in rocks and they fracture. Scientists estimate there are several million earthquakes each year. Every earthquake produces P waves and S waves but only larger earthquakes produce Love waves and Rayleigh waves. These are the four major types of seismic waves.
How seismic waves move through the Earth, USGS
P waves are compression waves
Every earthquake creates P waves and S waves. P waves travel away from the focus of an earthquake where the rocks first fractured by compressing and expanding the rocks as they travel through solids, liquids and gases. P waves travel through all parts of the Earth.
S waves are transverse waves
S waves travel in a motion similar to a rope held tight at one end while the other end is lifted rapidly back and forth. S waves only travel through solids and do not travel through the liquid outer core of the Earth.
Formation of surface waves
When P waves and S waves reach the Earth's surface they are transformed into surface waves. Love waves and Rayleigh waves were discovered by two Englishmen.
Love waves are transverse waves
Love waves move back and forth in the direction they are traveling. Take a slinky and lay it on a table and make waves that move through the slinky as you move it back and forth. This is similar to the action of Love waves.
Circular motion of Rayleigh waves
Rayleigh waves also move on the surface but are closer to how waves in the ocean move. Their movement is circular in motion as they move through the Earth but the circular motion is retrograde meaning the waves circle backward as they move forward.
Great earthquake waves
Body waves and surface waves are the two types of seismic waves formed during great earthquakes. P waves and S waves are called body waves because they travel through the body of the Earth.
Seismic waves that cause the most damage
Love waves and Rayleigh waves travel only on the surface of the Earth and cause the most destruction. Love waves travel at 10,000 miles per hour as they race around the Earth's surface.
Rayleigh waves circling the Earth
The Rayleigh waves travel slightly slower at 7800 miles per hour while circling the globe. These waves circle the Earth sometimes for more than a week after a great earthquake. Scientists say it is something like vibrations in the ringing of a bell.
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