Abstract: Disclosed is a measurement system for measuring subsurface resistivity. The surfaces of interest are, for example, engineered surfaces such as roads and dams, and non-engineered surfaces such as greenfield sites. The measurement system may also be used on biological materials. The system includes signal input electrodes for inputting an input signal into subsurface material by capacitive coupling. Pairs of signal detection electrodes allow capacitive coupling detection of a detectable signal caused by the input signal in at least some of the subsurface material. A phase-sensitive meter such as a lock-in amplifier is provided to measure the amplitude and phase of the detectable signal.