The use of three-dimensional (3D) three-component (3C) shallow seismic refraction method to find the source of salt at two sites in NSW, Australia

Three-dimensional (3D) three-component (3C) shallow seismic refraction surveys were recorded over a shear zone at two sites associated with dryland salinity in the Spicers Creek Catchment, near Dubbo in southeastern Australia. The seismic data were recorded with the Australian National Seismic Imaging Resources (ANSIR) 360-trace, ARAM24 seismic system and IVI MiniVibe model T-15000. The broad objective of this study was to use seismic refraction method to map in detail a shear zone, which is associated with the salination. Seismic refraction method was selected because of their potential ability to provide greater lateral resolution of the narrow vertical shear zone, than is currently the norm with electrical and electromagnetic methods. This situation was confirmed with a number of resistivity depth images and magnetic images generated as part of study. The seismic refraction surveys in the study area show that the shear zone occurs as a narrow region with low velocities and increased depths of weathering. The cross-cutting features associated with the major shear zone show that saline groundwater can discharge at the surface where increased volumes of groundwater occur at the intersection of different sets of shears. This model provides a useful explanation for the discontinuous occurrence of salination along the major shear zone.