SeismicMethods and Engineering Flashcards
(22 cards)
The study of earthquakes
Seismology
What Geoscientists use to record seismic waves
seismometers (Geophone)
packets of energy that travel through the earth, they can be generated by earthquakes, landslides, eruptions, explosions, and many other phenome
Seismic Waves
measure displacement of the surface caused by the passing seismic wave
Seismograms
Distance between 2 adjacent points that have the same displacement(phase).
Wavelength
The time it takes for 2 successive crests to pass a reference point
Period = T
Is the number of repetitions per unit of time and it has units of hertz
Frequency
Seismic waves that travel through the earth layers
Body Waves
seismic waves that displace the
medium in the direction of wave propagation, in other words, particles
in the medium move back and forth in the same direction as the path
of the pulse through the rock
Compressional waves (P-waves)
seismic waves whose oscillations are perpendicular to the direction of wave propagation
transverse wave is also known as a shear wave, or S-wave
. The application of force on the surface of an object is
called…..
stress
is a measure of how resistant to compression that object is
bulk modulus (Κ)
Formula for Shear Modulus
u = Ts/(L2-L1)/L
Formula for stress
N = F/A
the ratio of shear stress to that of shear strain
Shear Modulus
The refraction of seismic waves at an interface is controlled by which law and what’s the formula
Snell’s law : sinTi/SinTr = v1/v2
The angle of refraction cannot exceed 90°, when a wave is refracted along the interface the
phenomenon is called…..
critical refraction
Critical refraction can only occur when……
medium 2 has a higher seismic velocity than medium 1
seismic waves that are of interest for engineers
-Rayleigh waves
-Love waves
waves cause the sur- face particles to move in ellipses
Rayleigh Waves
type of surface wave that is horizontally polarized
Love Waves
