HGI has applied seismic survey methods to improving the understanding of numerous geological, geotechnical, and hydrogeological projects for over 20 years. Seismic methods are ideally suited to investigating layered media and we employ a variety of techniques, including seismic refraction, seismic reflection, and multi-channel analysis of surface waves (MASW), to perform both large- and small-scale surveys. HGI has conducted surveys in a variety of situations from large scale seismic refraction surveys in very rugged terrain to small scale MASW surveys in dense urban areas. Seismic methods are applicable to many areas including: depth to bedrock surveys, rock rippability studies, stratigraphic mapping, void detection, water table mapping, seismic hazard determination, and fault mapping.
Seismic methods are ideally suited for investigating layered media; the seismic refraction, seismic reflection, and surface wave methods can be tailored to a variety of applications.
Seismic surveys measure acoustic velocity (the speed at which sound waves propagate) in earth materials. There is a direct relationship between acoustic velocity and material density (dense materials propagate sound faster than loose materials); therefore, seismic velocities can be interpreted to determine the subsurface conditions below a survey area, providing a high resolution noninvasive option for studying the earth’s interior.