Gravity or micro-gravity surveys consist in measuring the relative changes in gravity from one place to another. Sharp relative changes in micro-gravity usually evidence drastic changes in the subsurface density of the underground material.
This method allows us to identify the geological scenario for sinkholes with the potential of damaging existing structures earlier in their development without more expensive and invasive techniques.
Results of one such survey are illustrated in the image to the left. The low micro-gravity anomaly (indicated in purple) help narrow down the areas of concern. Follow up actions from geotechnical or civil engineers can concentrate further investigative efforts in these areas.