Cavities and geological anomalies detection

The geological anomalies are represented with contours of hot and cold colors. The four boreholes are represented by black crosses. They allowed a better understanding of the results of the DCOS analysis and to locate a cavity.

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Borehole results:

• A cavity was found on the borehole F1 between 14.2 m and 18 m. It develops on a level of altered limestone.
• F2 performed in the "neutral" zone revealed nothing.
• F3 showed the presence of a water table.
• F4 crossed a reworked zone composed of different kind of embankments

This electromagnetic prospecting method allows the recognition of conductive or resistant areas at depths of up to several tens of meters. The results obtained did not allow the implementation of control boreholes.

The four boreholes defined with the results of DCOS analysis are represented by red circles

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  Profils Nord-Sud
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  Profils Est-Ouest

This Electrical Resistivity Tomography prospecting method called dipole-dipole consists in injecting into the soil a direct current by means of two transmitting electrodes and measuring a potential difference between two remote receiving electrodes. The results have failed to implement drilling controls.This Electrical Resistivity Tomography prospecting method called dipole-dipole consists in injecting into the soil a direct current by means of two transmitting electrodes and measuring a potential difference between two remote receiving electrodes. The results have failed to implement drilling controls.

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  The four boreholes are indicated
  by red circles.

Micro-gravimeter based on the measurement of the variation of gravity at the surface due to defects or excess mass in depth. The results have failed to implement drilling controls.

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  The four boreholes
  are indicated by black crosses.