Abstract: This invention provides an understanding of the structure and porosity of soil and stony regions. The method is characterized by release of a measuring gas in the region being investigated and its penetration through the investigated region to several places where it is captured and measured. Thus, the measured data from the various measuring locations provides the structure and the porosity of the region being investigated. The method is especially suited for the investigation of dams and the location of underground cavities and tectonic faults.