Whether the objective is estimating depth to bedrock, mapping overburden, investigating permafrost, or supporting infrastructure development, resistivity surveys provide valuable information about changes in the shallow subsurface.

Capacitively Coupled Resistivity (CCR) is a rapid electrical geophysical method designed for shallow resistivity investigations. Unlike electrode-based resistivity systems, CCR uses towed transmitter and receiver antenna arrays to collect resistivity measurements continuously as the survey moves.

Electrode-based resistivity surveys require crews to install electrodes in the ground at regular intervals before data can be collected. This approach generally provides greater investigation depth and higher data quality, but can be slow where survey lines are long or ground conditions make electrode installation difficult, such as frozen ground, coarse sediments, or exposed bedrock. CCR eliminates the need for ground electrodes, allowing large areas to be surveyed much more efficiently. While investigation depth is generally shallower than electrode-based resistivity surveys, the significant increase in productivity makes CCR well suited to regional mineral exploration, geotechnical investigations, and other projects where rapid shallow resistivity mapping is the primary objective.

CCR surveys are typically completed by towing a transmitter and receiver array behind a vehicle, snowmobile, ATV, or by hand, depending on terrain and project requirements. As the system moves along the survey line, resistivity measurements are collected continuously, producing dense datasets with excellent spatial coverage at significantly higher collection rates than conventional electrode-based resistivity surveys. CCR is particularly attractive for long traverses, winter programs, and projects where rapid coverage is important.

We operate two capacitively coupled resistivity systems, allowing survey configurations to be matched to project objectives.

Aurora Rapid Reactance Tomography (ARRT)

ARRT is Aurora's proprietary CCR system, developed for high-productivity exploration programs. It supports simultaneous multi-frequency acquisition, flexible array configurations, integrated GNSS positioning, and larger receiver arrays than conventional CCR systems. These features make it well suited to regional mineral exploration and projects requiring efficient coverage over large areas.

OhmMapper™

The OhmMapper™ is a well-established commercial CCR system widely used for shallow engineering, environmental, and geotechnical investigations. Its narrow signal bandwidth operation, compact design and straightforward deployment make it an effective solution for many site investigations and corridor studies.

Productivity: ARRT Up to 60 km/day --- OhmMapper Up to 20 km/day

Transmitter power: ARRT 80–100 W --- OhmMapper 16 W

Frequencies: ARRT Up to 5 simultaneous --- OhmMapper Single (~16.5 kHz)

Sampling rate: ARRT 3 Hz --- OhmMapper 1–2 Hz

Receivers: ARRT Up to 20 --- OhmMapper Up to 5

Integrated GNSS: ARRT Yes --- OhmMapper No

Array configurations: ARRT Dipole-dipole, inline, equatorial --- OhmMapper Inline dipole-dipole

Dipole lengths: ARRT 5, 10, 20, 40 m --- OhmMapper 5, 10, 20 m

Depth of investigation: ARRT ~120 m --- OhmMapper ~60 m

3D mapping: ARRT Yes --- OhmMapper No

Inversion: ARRT 2D, 2.5D, and 3D --- OhmMapper 2D, 2.5D, and 3D

* Survey productivity depends on the number of receivers in operation, terrain, survey design, and project logistics.

** Investigation depth depends on subsurface resistivity, array geometry, and electromagnetic skin depth.

Both systems measure shallow subsurface resistivity using the same underlying geophysical principle. The choice depends primarily on project objectives.

For large mineral exploration programs requiring flexible survey configurations and high production rates, ARRT offers significant operational advantages. For engineering, environmental, and smaller-scale geotechnical and mineral deposit investigations, the OhmMapper™ provides a proven and effective solution.