Induced Polarization (IP) and Complex Resistivity

Induced polarization and complex resistivity are geophysical measurement methods that characterize subsurface electrical properties beyond simple DC resistivity. Standard resistivity surveys measure how strongly the ground resists electrical current flow. IP and complex resistivity go further by measuring how the ground stores and releases electrical charge, and how its resistivity changes with the frequency of the applied current. Together, these parameters build a more complete picture of subsurface material composition than resistivity alone provides.

Complex resistivity expresses the ground’s response to alternating current as a complex number containing both a real component representing resistive behavior and an imaginary component representing capacitive or polarizable behavior. Surveyors measure both components simultaneously across a range of frequencies, producing a spectrum of ground response data. This spectral IP approach identifies the frequency-dependent signature of different polarization mechanisms, separating metallic mineral grain polarization from clay membrane polarization and pore fluid effects within the same data set.

Field surveys inject alternating or switched DC current into the ground through transmitter electrodes. Receiver electrodes measure the resulting voltage waveforms at defined offsets along the survey line. Time-domain measurements record voltage decay after current cutoff. Frequency-domain measurements record phase shift and amplitude ratio between injected current and measured voltage across multiple frequencies. Modern multi-channel IP receivers acquire data from multiple electrode spacings simultaneously, increasing survey productivity on large exploration grids.

In Pakistan, IP and complex resistivity surveys support copper and gold exploration in Balochistan, base metal prospecting in KPK, groundwater salinity mapping in Sindh and southern Punjab, and environmental investigations around industrial contamination sites where subsurface fluid chemistry affects ground electrical properties.

Tactical Supply Pakistan supplies IP and complex resistivity survey instruments for mineral exploration, hydrogeological, and environmental geophysical applications across Pakistan.