Exploration Seismology Exam 1
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Hookes Law
Statement of linear relationship between stress and strain
Applies to "elastic" region of materials
σ=Cε
C: "stiffness" of spring

Shear Modulus (μ)
Ratio of shear stress to shear strain
Units of pressure (Pa)

Young's Modulus (E)
Ratio of
normal stress to
normal strain
Units of pressure (Pa)

Poison's Ratio (σ)
Ratio of negative of transverse strain to longitudinal strain
no units

Bulk Modulus (k)
Ratio of pressure to change in volume (dilatation)


Shear Modulus of liquids
μ=0

Stress
Force per area
Units of pressure

Strain
Change in shape or dimension
No units

Example of low poison's ratio
sponge

Example of high poison's ratio
Lead cylinder

Group Velocity
Connect inside branches of Christmas tree image

Phase Velocity
Branches of Christmas tree

Relationship of Amplitude and Radius

Relationship of Energy and Amplitude
(Directly Proportional)

Isotropic
All properties in a material are the same throughout

Relationship of Energy and Radius

Sampling Theorem
A signal can be competely reconstructed if it is sampled at least 2x per cyle
If not, it appears to be a totally different signal (aliasing)

Huygen's Principle
Every point on a wavefront serves as a new source of waves


Slope of refracted arrival



Hyperbolic Travel Time Equation

Standard form for traveltime expression


Fermat's principle
The first arrival of a wave will be from the path of least resistance

Max Swave velocity
.7 of pwave velocity

4 assumptions of boundary conditions (z equations)
Continuity of Normal Displacement
Continuity of Tangential Displacement
Continuity of Normal Stress
Continuity of Tangential Stress