Introduction to Electrical Resistivity Tomography (ERT)

Electrical Resistivity Tomography (ERT) is a geophysical method to image sub-surface structures by injecting electrical currents and measuring the resulting potential differences. It's widely used in environmental studies, archaeology, and engineering.

ERT involves placing electrodes in the ground in a specific pattern. Electrical currents are injected through these electrodes, and the resulting voltage differences are measured to calculate the resistivity of subsurface materials.

Soil composition, moisture content, and temperature significantly influence resistivity. Interestingly, clay-rich soils have lower resistivity due to their high ion-exchange capacity, while sandy soils exhibit higher resistivity.

ERT is not just for imaging. It can monitor dynamic processes like groundwater flow, and even detect contaminant plumes. Recent advancements have enabled 4D ERT, allowing real-time monitoring of subsurface changes.

Integration with machine learning is transforming ERT. Algorithms enhance data interpretation, predict subsurface features with higher accuracy, and reduce the need for invasive drilling, making ERT more efficient and environmentally friendly.

ERT has been proposed for future Mars missions to image subsurface water ice, revealing the planet's water history without drilling.