Which type of electrical phenomenon involves movement through underground materials?

The phenomenon that involves movement through underground materials is telluric currents. Telluric currents are natural electric currents that flow through the Earth, primarily due to geophysical processes such as solar wind interactions with the Earth's magnetic field. These currents can travel through conductive underground materials, influenced by variations in the Earth's geology, mineral content, and moisture levels.

Understanding telluric currents is essential in fields like geophysics and can also be relevant in cathodic protection systems, as they can affect measurements and interpretations related to soil and underground conductor resistivity. This knowledge is useful for technicians in the field to accurately assess the conditions of cathodic protection systems and ensure effective operation.

The other choices—such as electrostatic discharge, ground loops, and high-frequency currents—represent different electrical phenomena that do not primarily involve the movement of current through underground materials in the same way as telluric currents.