The variation in resistance measured through the ERT technique usually corresponds with the variations found beneath the surface due to factors like water content, porosity, and permeability.

ERT data is collected by inducing current into the ground between electrodes, and the potential difference is then found using a different pair of electrodes. In the field, a series of electrode pairings are planted in the ground at regular intervals within the test area and are connected to a central control unit. ERT can generate a 1D sounding, as well as 2D or 3D profiles.

ERT has many applications and can be used for projects including:

• Electrical grounding for substations
• Discovering the variations of characteristics in underground rocks (lithology)
• Mapping bedrock
• Voiding and fracture zones in rock
• Sinkholes in karstic environments (this is when soluble rocks such as limestone, dolomite, and gypsum have dissolved over time)

Read about our previous ERT projects:

• Assessing the Structural Integrity of Stopbanks
• Determining Location and Extent of Landfill
• Detecting Voids in a Karstic Environment
• Site Classification Investigations for Subdivision Developments