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Seismic Waves Essay

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Hey everyone, my names Samreen and today I’ll be informing you guys all about Seismic waves in relation to Earthquakes. In other words, we’ll be looking at Seismology, which is the study of the passage of elastic waves through the Earth.
Seismic waves are waves of energy caused by the sudden breaking of rock within the earth or an explosion; these waves are the energy that is transmitted through the earth which is recorded on seismographs, which measures, amplifies, and records the motion of the ground (Endsley, 2016). Many different processes generate seismic waves, including earthquakes.
An Earthquake occurs when there is a sudden movement of the Earth’s crust resulting from the building up of stored energy between two stuck lithospheric …show more content…

The linear relationship between applied stress (σ) and resulting strain (∈) is: σ=E∈ Where, E equals the constant of proportionality called an elastic modulus
The original volume (VO) change to final volume (VF) when compared to the pressure change is called bulk modulus (K); which is the measure of the incompressibility of the material.
K=V_O (P-P_O )/(V_O-V_F)
When deforming a solid state by simple shear, a shear strain (Y) is induced by applying a shear stress (σ).
The ratio of these quantities is the rigidity modulus (G):
G=σ/Y
The units of elastic modulus are the same as pressure, MPa (Mega Pascal) or GPa (Giga Pascal).
The bulk modulus (K) and the rigidity modulus (G) are always positive, which means that the velocity of p-waves is always greater than s-waves. S-waves cannot propagate through a liquid medium, this theory is proven when G = 0 is substituted for liquids; the velocity of the wave equals zero (Ucl.ac.uk, 2016).
There are two different types of seismic waves produced during an earthquake; body waves and surface waves.
Body waves travel through the earth’s inner layers. They are reflected and transmitted at interfaces where seismic velocity and/or density change, and they obey Snell’s law (Physicsclassroom.com, 2016), which states that: the ratio of the sines of the angles of incidence and refraction of a wave are constant when it passes through two given media. P-waves and

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