||Application of Seismic Shear Wave Studies to the Investigation of Aquifers.
Bennet, Hugh F. ;
||Michigan State Univ., East Lansing. Dept. of Geology.
||DI-14-01-0001-1513; OWRR-B-006-MICH; 05202,; B-006-MICH(3)
( Aquifers ;
Seismic refraction method) ;
( Ground water ;
Remote sensing) ;
Seismic waves ;
Rayleigh waves ;
Water table ;
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The use of seismic shear waves to evaluate ground water aquifers was investigated. The study centered around the generation and detection of shear waves in an area consisting of 500 feet of loosely consolidated sands with water table being between 5 feet and 35 feet. The generation of shear waves over long distances was unsuccessful and the study turned to identifying shear wave arrivals on the three component recording array. Compressional to shear wave conversions from the base of the sand layer indicate that shear wave velocities increase in the saturated sand. This observation is confirmed by the normal dispersion of the Rayleigh Wave Train. Most noticeable is the five-fold increase in compressional wave velocity in the saturated sand as compared to the velocity in the dry surface layer. This factor causes much of the source energy to be trapped in a surface layer wave guide giving rise to long surface wave trains. The change in compressional wave velocity at the water table interface may be a potential indicator of aquifer porosity. (Author)