Scribd
Upload
108 views3 pages

Types of Earthquake Waves

There are three main types of earthquake waves: 1) P waves are fast body waves that alternately compress and dilate rock as they travel, able to pass through both solid rock and liquid. 2) Slower S waves are also body waves that cause rock to shear sideways at right angles to the direction of travel, unable to pass through liquid. 3) Surface waves are restricted to near the ground surface, including Love waves that move horizontally at right angles to propagation and Rayleigh waves that move both vertically and horizontally in the direction of travel. Surface waves cause the most damage to structures.

Uploaded by

Bobby Wsk
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
108 views3 pages

Types of Earthquake Waves

There are three main types of earthquake waves: 1) P waves are fast body waves that alternately compress and dilate rock as they travel, able to pass through both solid rock and liquid. 2) Slower S waves are also body waves that cause rock to shear sideways at right angles to the direction of travel, unable to pass through liquid. 3) Surface waves are restricted to near the ground surface, including Love waves that move horizontally at right angles to propagation and Rayleigh waves that move both vertically and horizontally in the direction of travel. Surface waves cause the most damage to structures.

Uploaded by

Bobby Wsk
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 3

3/10/2014

Types Of Earthquake Waves

TYPES OF EARTHQUAKE WAVES


Earthquake shaking and damage is the result of three basic types of elastic waves. Two of the three propagate within a body of rock. The faster of these body waves is called the primary or P wave. Its motion is the same as that of a sound wave in that, as it spreads out, it alternately pushes (compresses) and pulls (dilates) the rock. These P waves are able to travel through both solid rock, such as granite mountains, and liquid material, such as volcanic magma or the water of the oceans.

The slower wave through the body of rock is called the secondary or S wave. As an S wave propagates, it shears the rock sideways at right angles to the direction of travel. If a liquid is sheared sideways or twisted, it will not spring back, hence S waves cannot propagate in the liquid parts of the earth, such as oceans and lakes.

The actual speed of P and S seismic waves depends on the density and elastic properties of the rocks and soil through which they pass. In most earthquakes, the P waves are felt first. The effect is similar to a sonic boom that bumps and rattles windows. Some seconds later, the S waves arrive with their up-and-down and side-to-side motion, shaking the ground surface vertically and horizontally. This is the wave motion that is so damaging to structures. The third general type of earthquake wave is called a surface wave, reason being is that its motion is restricted to near the ground surface. Such waves correspond to ripples of water that travel across a lake.
http://allshookup.org/quakes/wavetype.htm 1/3

3/10/2014

Types Of Earthquake Waves

Surface waves in earthquakes can be divided into two types. The first is called a Love wave. Its motion is essentially that of S waves that have no vertical displacement; it moves the ground from side to side in a horizontal plane but at right angles to the direction of propagation. The horizontal shaking of Love waves is particuly damaging to the foundations of structures.

The second type of surface wave is known as a Rayleigh wave. Like rolling ocean waves, Rayleigh waves wave move both vertically and horizontally in a vertical plane pointed in the direction in which the waves are travelling.

Surface waves travel more slowly than body waves (P and S); and of the two surface waves, Love waves generally travel faster than Rayleigh waves. Love waves (do not propagate through water) can effect surface water only insofar as the sides of lakes and ocean bays pushing water sideways like the sides of a vibrating tank, whereas Rayleigh waves, becasuse of their vertical component of their motion can affect the bodies of water such as lakes. P and S waves have a characteristic which effects shaking: when they move through layers of rock in the crust, they are reflected or refracted at the interfaces between rock types. Whenever either wave is refracted or reflected, some of the energy of one type is converted to waves of the other type. A common example; a P wave travels upwards and strikes the bottom of a layer of alluvium, part of its energy will pass upward through the alluvium as a P wave and part will pass upward as the converted S-wave motion. Noting also that part of the energy will also be reflected back downward as P and S waves.
WAVE PROPERTIES
http://allshookup.org/quakes/wavetype.htm 2/3

3/10/2014

Types Of Earthquake Waves

SOUND AND LIGHT WAVES Seismic Home

http://allshookup.org/quakes/wavetype.htm

3/3

You might also like