Seismic Reflection

Sevar Dilkhaz
Geotechnical Earthquake Engineering Course
Eastern Mediterranean University

What is reflection in general?
When we speak our vocal cords produce vibration they
rippled around the earth and this vibration been
resistance back. It is called Reflection.
12/16/2014 2Sevar Dilkhaz

“Reflection in Sound“

Our Sound Vibration ………….

Reflection of Sound in Bats?
Bats can not see so they send sound or waves to
objects.
They received like a picture sound of objects.
12/16/2014 Sevar Dilkhaz 5

Reflection of Sound by Bats.

“Seismic Reflection”
A. This method uses the reflected waves
from reflectors in the ground to perform the tests.
B. The reflectors may be surfaces of discontinuities or
concentrated defects.
C. In the method of refraction the transducers were
located in a line from the source and outwards,
sometimes to very long distances. In this method the
transducers are located around the point of
excitation.

“Reflection In Ship”
special ships fitted with equipment that produces waves
are used to locate oil and gaz , these waves fan out
below the surface of the water penetrating the sea bed
below and depending on what they hit on what they
hit (rock, oil, or gaz) they reflected at different speeds
back up towards the ship their seismometers record
the waves and how fast they are travelling. These
microphones are evenly spaced on the cable up to
twelve kilometers long which is dragged behind the
ship along the surface above the water.

“Specific Ship(Off-shore seismic)

What Is Angle of Incidence?
The angle which the seismic wave is travelled by it to
reach the sea surface or any other surfaces.

Reflection and Transmission at
normal incidence:
the seismic reflection coefficient R , determined by
the impedance contrast between the two material For
a wave that hits a boundary at normal incidence
(head-on), the expression for the reflection coefficient
is simply:

normal incidence:
Z0 = Impedance of the first medium .
Z1 = Impedance of the second medium.

Types of Reflection and
Transmission:
 Reflection and Transmission at normal incidence:
When a seismic wave encounters a boundary between
two materials with different acoustic impedances,
some of the energy in the wave will be reflected at the
boundary, while some of the energy will be
transmitted through the boundary.

non-normal incidence:
The situation becomes much more complicated in the
case of non-normal incidence, due to mode conversion
between P-waves and S-waves, and is described by
the Zoeppritz equations. In 1919, Karl Zoeppritz
derived 4 equations that determine the amplitudes of
reflected and refracted waves at a planar interface for
an incident P-wave.

References:
https://www.youtube.com/watch?v=H6FPfGe9lIo
http://en.wikipedia.org/wiki/Reflection_seismology#I
nterpretation_of_reflections
R. L. a. H. Jadi, "DETERMINATION OF DYNAMIC
SOIL PROPERTIES USING GEOPHYSICAL
METHODS," in International Conference on the
Application of Geophysical and NDT Methodologies to
Transportation Facilities and Infrastructure, St. Louis,
MO,, December 2000.

Thanks for your attention 
Your Questions please!

Seismic Reflection

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