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What is Electrical Resistivity Tomography (ERT)? | Comprehensive Guide

1. Technical Definition & Principles

ERT reconstructs 3D subsurface resistivity models through electrode arrays. When geological structures (e.g., rock layers with 10-1000 Ω·m resistivity) exhibit conductivity differences, Geotech’s systems (such as the WGMD-10X) inject 0.1-5A currents and measure millivolt-level potential differences for inversion calculations.

2. Core Components of ERT Systems

ComponentTechnical SpecificationsGeotech Model
Electrode ArrayStainless steel electrodes, adjustable spacing (5-20m)WGMD-9 Array System
Data Acquisition24-bit ADC, 0.1mV accuracyWDAS-3 Digital Unit
Power Supply800V/5A DC pulse powerWDF-5 Power Module
Analysis Software3D nonlinear inversion algorithmsGeoERT Pro Software
resistivity/IP/SP imaging systems

3. Key Advantages & Limitations

✔ Core Advantages

  • ​Non-invasive detection: Covers 200×200m area per measurement
  • ​Real-time imaging: Data refresh rate ≤5 seconds (WGMD-10X)
  • ​Multi-scenario adaptability: Detects depths from 0.5m to 300m
  • ​Cost efficiency: 60% lower cost compared to seismic surveys

✖ Technical Limitations

  • ​Depth constraints: ≤300m in standard mode (WGMD-9)
  • ​Terrain requirements: Surface slope <15°

4. Innovative Exploration Methods

Geotech’s patented 3D cross-hole ERT technology achieves precision breakthroughs:ρapp​=k⋅IΔV​

Where k = device coefficient (Wenner array k=2πa). Multi-borehole joint inversion enhances resolution to 0.3m (vs. 1.2m traditional methods).

Field Implementation Workflow

  1. ​Electrode deployment: 64 electrodes in 5×5 grid
  2. ​Parameter setup: Select Schlumberger measurement sequence
  3. ​Data acquisition: Automatically collect 512 potential difference datasets
  4. ​Quality control: Real-time SNR monitoring (>20dB)
  5. ​Data inversion: Apply constrained least-squares algorithm

5. Typical Application Scenarios

Case 1: Gold Exploration

Project: WGMD-10X deployment in California mining area, USA
Results: Identified 800m continuous low-resistivity zone (<50Ω·m), drilling verification showed <8% error in gold vein thickness

Case 2: Highway Survey

Technology: Cross-hole high-density ERT (0.5m electrode spacing)
Data: Anomaly positioning accuracy ±0.2m, 65% improvement over traditional methods

6. ERT vs. High-Density Resistivity Method

ParameterERTHigh-Density Method
Electrode Channels32-64 channels128-512 channels
Survey Speed200 points/hour1000 points/hour
Depth Range0.5-300m0.1-100m
Resolution0.5m0.1m
Recommended DeviceWGMD-9WGMD-10V

Mineral Exploration Package
WGMD-10X + SSIP System:

  • Depth: 500m
  • Resolution: 0.5m
  • Applications: Metal ores, geothermal fields

Engineering Survey Kit
WGMD-4 Portable ERT:

  • Weight: <15kg
  • Speed: 100 points/hour
  • Applications: Tunnel inspection, archaeological surveys

For more information on ERT and its applications, visit Geotech’s product page：

For more information on ERT and its applications, visit Geotech’s product page：

Geotech Products| Geotech Instrument Co., Ltd. (geotechcn.net)

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