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.

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“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.

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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:



Z0 = Impedance of the first medium .

Z1 = Impedance of the second medium.


Types of Reflection and Transmission:


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.


Reflection and Transmission at non-normal incidence:

The situation becomes much more complicated in thecase of non-normal incidence, due to mode conversionbetween P-waves and S-waves, and is described bythe Zoeppritz equations. In 1919, Karl Zoeppritzderived 4 equations that determine the amplitudes ofreflected and refracted waves at a planar interface foran incident P-wave.


References:https://www.youtube.com/watch?v=H6FPfGe9lIo

http://en.wikipedia.org/wiki/Reflection_seismology#Interpretation_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.


https://www.youtube.com/watch?v=H6FPfGe9lIo

http://en.wikipedia.org/wiki/Reflection_seismology

Thanks for your attention

Your Questions please!
