A Summary Of Methods For Locating And Mapping Fractures And Cavities With Emphasis On Geophysical Methods

Assessing the existence, location and mapping of geologic anomalies, such as fractures, cavities within soil<br>and rock are common to both engineering and hydrologic project needs. Spatial considerations of such a<br>site characterization must address the detection probabilities involved by using boreholes alone. Spatial<br>considerations must also include the characteristic dimensions of the fracture/cavity system, including<br>size, depth and perkxlicity and an appreciation of methods other than drilling to improve the probability of<br>detection.<br>A summary of the common methods available for fracture and cavity detection mapping (non-geophysical<br>as well as geophysical) are presented along with their spatial sampling and limitations. The remote sensing<br>and geophysical methods are but a small part of this list. However, they include some of the most effective<br>methods for fracture and cavity detection and mapping. They cover the complete range of spatial<br>sampling, from regional to no more than the localized borehole wall. The airborne, remote sensing,<br>surface, and downhole geophysical methods along with methods that can be used on water covered areas<br>are identified along with their spatial sampling capabilities. An understanding of the tools available and<br>their spatial sampling limitations are a necessary part of planning and carrying out an effective<br>fracture/cavity investigation.