Method and apparatus for producing shear waves for subsurface geophysical investigation
AssigneePrakla-Seismos GmbH
InventorHans A. K. Edelmann
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Abstract
Two or a larger even number of compressional wave producing vibrators are symmetrically disposed in two groups on opposite sides of a profile line in closely spaced relationship. The vibrators are energized by the same (or identical) sweep signals, the signals to one vibrator (or group) on one side of the line being separated in phase by 180.degree. from the signals to the vibrator or group on the other side. P-wave components are thereby cancelled, leaving the shear waves to be propagated.
Claims7
A process for producing shear waves in the earth for geophysical examination of the sub-soil comprising the steps of
- providing at least two vibrators of the type usable for the production of compressional waves in the earth,
- locating the vibrators in spaced, adjacent relationship with the bottom surfaces thereof in coupling contact with the surface of the earth, and
- concurrently energizing the vibrators with identical sweep signals in counterphase relationship.
An apparatus for producing essentially horizontally polarized shear waves in the earth for sub-soil geophysical examination comprising
- an even number of compression wave vibrators, said vibrators being located in closely spaced symmtrical array with half of the vibrators being located on each side of a central line and coupled to the earth's surface;
- and
- means for energizing the half of said vibrators on one side of the line with a first sweep signal and the other half of said vibrators with a substantially identical second sweep signal separated in phase from said first signal by substantially 180.degree..
Dependencies are inferred from the claim text.