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tTEM is a groundbased method for transient electromagnetic data acquisition and is the HGG group's most recent development in TEM systems. The aim of the tTEM development has been to design a system covering the depth range from 0 – 30 m in full 3D. This important part of the subsurface is not covered  by any other cost efficient geophysical method. In reality the system “sees” deeper to more than 70 m with a distance between soundings of 3 – 4 m. Typical distances between lines is 10 – 20 m resulting in a full 3D resulting of the subsurface.

The system is quick to deploy and easily managed by a field crew of two persons. It consists of an ATV towing the transmitter and receiver coils. To make it robust on even harsh farm fields the coils are mounted on sledges with runners.

The tTEM system is seemly integrated with the Aarhus Workbench software package for data processing, inversion and reporting.

Key Specifications

  • Dual moment towed TEM-system
  • Offset configuration, offset: 9.5 m
  • Depth of investigation: 50 - 100 m
  • Drive speed: 4-5 m/s (15-20 km/h)  
  • Daily production rate on farm fields: 100-250 hectares
  • Peak current: 30 Amp (high moment)
  • Transmitter moment:  19, 240 Amp/m2 (low, high moment)  
  • Transmitter period time: 0.6 ms, 1.4 ms (low, high moment)
  • Turn off time: 2.5 microseconds (low moment)


tTEM system paper – a Towed TEM system for Detailed 3D Imaging of the Top 70 meters of the Subsurface: Geophysics. Auken, E., Foged, N., Larsen, J. J., Lassen, K. V. T., Maurya, P. K., Dath, S. M., and Eiskjær, T., 2018 - pdf

tTEM white paper - pdf

tTEM case studies:
1. Assessment of managed aquifer recharge sites using a new geophysical imaging method: Vadose Zone Journal. Behroozmand, A.A., Auken, E., Knight, R., 2019. - pdf

2.  A new towed geophysical transient electromagnetic system for near-surface mapping, Preview. Auken, E., Pedersen, J. B. & Maurya, P. K., 2018,33-35. - pdf