Seismic waves are
mechanical perturbation that travel in the earth at a speed governed by an
acoustic impedance of the medium in which they are travelling. When seismic
waves are travelling through the earth surface, it encounters an interface
between two materials with different acoustic impedance, some of the waves will
reflect back while some will refract through the boundary.
The seismic reflection techniques
involve the wave being generated, and measuring the time taken for the wave to
travel from the source , https://www.blogger.com/blogger.g?blogID=2978793373864847177#editor/target=post;postID=251310418891547220;onPublishedMenu=allposts;onClosedMenu=allposts;postNum=1;src=link reflect back from the interface and be detected by
receivers called geophones at the surface.
Seismic reflection
techniques is relatively expensive than the refraction method and is mostly
used for exploration work. It cannot be used for shallow depth because
reflection records are very difficult to interpret for shallow depth.
by knowing
the travel time from various shot guns to the geophones, and the velocity of
the seismic waves, a geophysicist then attempt to reconstruct the pathways of
the waves in order to build to an image of the subsurface.
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