Dear Konstantinos:

As a seismic method interpreter, I can say you that the seismic reflection method and ground-penetrating radar (GPR) are geophysical reconnaissance tools for the illumination of the subsurface. Both techniques are based on wave propagation and reflection, but wave length ranges, and consequently resolution and penetration depths, differ significantly.

GPR measures changes in the electromagnetic properties of sediments that cause reflection of electromagnetic energy. These changes in electromagnetic properties result primarily from changes in water content, governed in turn by grain-size and porosity (Topp et al., 1980; Roth et al., 1990; Sutinen, 1992; Huggenberger, 1993).

The practices of ground-penetrating radar (GPR) and time-domain reflectometry (TDR) are based on propagation and reflection of electromagnetic energy in the subsurface. The (frequency-dependent) properties that control the behavior of electromagnetic energy in a medium are dielectric permittivity (ε), where ε = ε0εr, electrical conductivity (σ), and magnetic permeability (µ), where µ = µ0µr (Von Hippel, 1954). Here, ε0 is the permittivity of vacuum (8.85419 10−12 F m−1), εr , is the relative permittivity, µ0 is the magnetic permeability of vacuum (4π10−7 H m−1), and µr is the relative magnetic permeability. Together, these properties define the impedance (Z) of the medium for harmonic electromagnetic waves with exp(jωt) dependence (Brewster and Annan, 1994; Fokkema et al., 2001):

Z = (jωµ/(σ+ jωε))pot 1/2

where:

j = (−1)pot1/2,

ω = 2π f is angular frequency [radians s−1], and

t is time [s].

The seismic reflection method has a better penetration but lower resolution than GPR. Also, the contrast parameter for the seismic reflection method (acoustic impedance) differs from that for GPR (electromagnetic wave impedance). In general, 250 MHz antenna frequency can provide the radar imaging data around 2 meters in depth for survey lines.

I recommend for example, the article "Mapping fractures with GPR: A case study from Turtle Mountain" Geophysics, Vol. 71, 5 Sept-Oct 2006; 10.1190/1.2335515.

Best regards, Mario E. Sigismondi