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Seismic Methods

Seismic geophysical methods use a seismic source and receivers to “see” the subsurface using compressional waves. The velocity of the seismic waves are recorded by the receivers, called geophones, and correlated to the material properties of the subsurface. Compressional (P-waves) waves are generated by a hammer and propagate down into the earth. Geophones “listen” for the waves to return to the earth’s surface. Careful analysis can tell us whether it is a direct surface wave, one reflected from a subsurface geologic interface, or a wave refracted along the top of a geologic interface.

More information on seismic surveys:

• Advanced Geologic Services
• Geovision Geophysical Services

Seismic Refraction

Seismic refraction measures the seismic velocity of the subsurface material, which is related to density and elastic properties and therefore can be correlated to a material type. It is more commonly used for shallow subsurface investigations than seismic reflection.

More information on seismic refraction:

• Colorado School of Mines
• Northeast Geophysical Services

Seismic Reflection

Seismic reflection measures the seismic velocity of the subsurface material, which is related to density and elastic properties and therefore can be correlated to a material type. It is different from seismic refraction in that it records the reflected seismic waves. Seismic reflection is commonly used in oil exploration and for deep subsurface exploration.

More information on seismic reflection:

• Northeast Geophysical Services

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Last updated: April 18, 2008