For beach landfalls, we use traditional land survey techniques to determine the topography, employing a combination of survey techniques that best suits the individual site conditions and accuracies required. We typically use RTK GPS systems, with the option of a base reference station. In areas not conducive to RTK GPS, such as built up areas and tall vegetation, the Surveyor delineates the boundary of the area with the RTK GPS and is charted accordingly. For landfalls that are inhospitable to our surveyors, such as cliffs, we use innovative methods such as specialist lasers to gather data regarding the nature of the site.
We also offer land UXO survey services using a magnetometer array fixed to our all-terrain ‘Argocat’ vehicle, and can provide environmental services if required.
Land seismic refraction is another service offered by our team. Depending upon the project requirements and anticipated geology, we use a variety of seismic sources including a hammer impacting a metal plate, buffalo guns, weight drops, and if required, explosive sources. As the seismic energy travels through the material, it is refracted and reflected at the interface between these layers.
Where the velocity of the underlying layer is higher than that of the above layer, some of the seismic energy is critically refracted along the interface, travelling at the velocity of the lower layer refracting energy back to the surface. Geophones are placed on the surface, typically in a line, to record the incoming refracted waves. Typical applications include mapping the depth to bedrock, determining the rippability of bedrock and locating faults and fractures.