Abstract

Shallow seismic reflection has been successfully applied to problems associated with groundwater contaminant movement and fate in a variety of geologic settings. Adaptation of seismic techniques developed for petroleum exploration to environmental targets shallower than 100 m generally entails more than linear downscaling. Increased dynamic range of recording equipment and computational speed of single-user processing hardware/software, coupled with the decreased cost of electronic equipment of all kinds, has made shallow seismic reflection a cost-effective method of imaging geologic targets relevant to near-surface site classification and eventual remediation. Reflection proved effective in mapping coherent events in shale continuous over distances as short as 20 m horizontal and provided detailed information about an acoustically significant shallow clay that was not an obvious drill horizon. Empirical evidence suggests the horizontal resolution of shallow seismic surveys could be less than suggested by Fresnel zone theory. Uncompensated near-surface velocity variations could result in inaccurate seismic interpretations. Shallow seismic reflection data demonstrate sufficient resolution to distinguish beds and associated geometries significant to movement in a variety of hydrologic and geologic settings.