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EARTH RESISTIVITY

Instruments for Earth Resistivity
Measurement of the subsoil

EARTH RESISTIVITY

Instruments for Earth Resistivity
Measurement of the subsoil
Instruments for Earth Resistivity Measurement of the subsoil

In geoelectric prospecting, the physical parameter that is determined is the electrical resistivity of the formations that constitute the subsoil and that can vary according to the lithotype, the degree of homogeneity, the degree of alteration and fracturing, the content in water and salts, the granulometry, etc. Other electrical methods, usually dedicated to mining research, geothermal energy or the dispersion of liquids in the ground, are instead based on the measurement of Self Potential or Induced Polarization.

From the classic 1D geoelectrical prospecting - usually performed using 4 electrodes - resistivity values are collected, at increasing depths below the vertical of the survey center (hence the name of Vertical Electric Surveys or VES).

The introduction of automated measurement techniques with the use of multielectrode cables has allowed the rapid development of Electrical Resistivity Tomography (ERT), able to return 2D profiles of high-resolution resistivity, particularly suitable for high resolution, small to medium depth of investigations. By combining several parallel resistivity profiles, a high-resolution 2.5D image can be obtained; with a larger number of electrodes it is even possible to perform true 3D and even 4D tomography investigations (introducing the time factor T), appropriately interpreted through sophisticated processing software.

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VES
To perform subsurface resistivity measurements in the event that the layering is flat and parallel, the Vertical Electrical Sounding technique is used (VES)

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HES
HORIZONTAL ELECTRICAL SURVEYS (HES): used especially in archaeology, they are realized with a "fixed" and easily transportable AMNB mini spreading, with which a series of fixed and limited in depth resistivity measurements are performed.

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SELF POTENTIAL (SP)
These are "passive geoelectric measurements" obtained with the help of two non-polarizable electrodes, measuring the "natural" variations of the electric potential of the soil without introducing current in the same.

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INDUCED POLARIZATION (IP)
This method is based on energizing the soil with an alternating current through the AB current electrodes for a certain time T, then measuring the equilibrium potential between the MN electrodes.

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ARCHAEOLOGY

ELECTRICAL RESISTIVITY TOMOGRAPHY
For electrical tomography, field investigation is performed in an automated manner using a multi-electrode cable with stakes distributed along a profile at a distance of a few meters.

HIGH RESOLUTION SURFACE INVESTIGATIONS OF LANDSLIDES, RIVER BANKS, POLLUTION DIFFUSION AREAS
CAVITY DETECTION AND BURIED OBJECTS
PEDOLOGICAL AND ARCHAEOLOGICAL INVESTIGATIONS
LANDFILL MONITORING
STUDIES OF GROUNDWATER CONTAMINATION BY SALT WATER
GROUNDWATER RESEARCH
MINERAL EXPLORATION