In this type of survey you examine low and high velocity layers down to the basement rock, and map tectonic features and quality changes. Features within the overlaying sedimentary layers are also investigated.
SHALLOW SEISMIC REFLECTION
Reflection surveys are becoming more and more popular for shallow studies thanks to significant improvements in the dynamic range of modern seismographs. Reflection surveys require powerful filtering, on-board trace scaling, high frequency energy sources and high frequency geophones for the best results.
MASW (MULTI-CHANNEL ACQUISITION OF SURFACE WAVES)
Determine engineering modulii through the measurement of surface or Rayleigh waves, all that is needed is an impulsive energy source such as a hammer or PEG-40, and a standard Geode with 4.5 Hz geophones. 1D or 2D measurements can be taken very quickly in the field.
For deeper investigations, record passively utilising background noise from traffic or construction as your energy sources. As these vibrations tend to be of a lower frequency, the resulting shearwave profile yields greater depths. Combine these measurements with active source measurements for a complete shear wave profile to the ground surface.