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Join us for this webinar designed to walk you through how you can use gravity and resistivity data to map subsurface cavities and low-density zones.

The resistivity data will be inverted in Res2DInv, while the gravity data will be processed using Oasis montaj and inverted using VOXI. We will correlate the two results with drillhole data modelled in Leapfrog.

Several research initiatives have shown us how the geophysical methods can be used to detect and characterise near-surface voids and undermining. The suitability of a geophysical method is for this application depends usually on the shape, size and depth of the void, including what it’s filled with. During the webinar, we will apply ground gravity and electrical resistivity imaging (ERI) to map the voids and cavities that may have formed due to undermining.

We will explain the unique characteristics of water-filled undermined areas, looking at lower density and electrical resistivity, and air-filled voids, usually characterised by increased electrical resistivity. We will also discuss voids associated with coal undermining, well-known for often being filled with acid mine water, which makes them conductive and have a low resistivity signature.

By the end of the webinar, you will be able to confidently:

  • Choosing an applicable geophysical technique
  • Use an integrated workflow that includes Oasis montaj, Res2DInv, VOXI and Leapfrog Geo to effectively delineate cavities.
  • Understand the results of your survey and effectively apply them to delineate possible cavities.



Victor Mapuranga

Geophysicist, Seequent


42:53 min

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