Geophysical techniques are commonly used to map subsurface properties of the ground. Numerous geophysical methods are used to map bedrock depths, locate fractures, map lithology and locate voids and other subsurface features. The following paragraphs illustrate some of the target for geophysical surveys and briefly describe the methods used. This section includes applying the various methods for both depth to bedrock and for locating fractures. Thus in some cases the techniques are discussed twice, each with the particular application in mind.

The methods most discussed are surface geophysical methods. However, for some problems in this, and the following Physical Properties section, logging methods are also important. The most important of these are presented in the relevant sections.