The basic task of the seismic refraction method is to determine the onset of artificially induced elastic seismic waves, in order to define the refraction depth along which the waves travel, and to calculate the velocity of elastic waves in media through which they propagate. The physical principle of seismic refraction lies in the fact that the induced wave is refracted at a critical angle along the boundaries of different geological layers, before it returns to the surface (see figure). The velocity of elastic waves serves as a basis for obtaining information on physical properties, i.e. composition of rock formations. Making use of the possibility of frequency analyses of recorded signals, it is possible to obtain additional information on rock formation properties Refraction waves are received on the surface of the investigated terrain by means of geophones in a linear arrangement, connected to a multi-channel seismograph.

Investigation of terrain composition for the elastic wave propagation velocity parameter and the determination of dynamic constants of rock elasticity, required for the construction of dams, foundations of large industrial facilities, bridges, ports, airports, pipelines, channels, roads, railroads, and subterranean structures such as tunnels, engineering rooms, and oil and gas storage facilities
Investigation of quarries and gravel and sand deposits

The method of seismic reflection is based on the definition of the times required for artificially induced elastic waves to be reflected by boundaries of different geological media, where the acoustic impedance of the media and forms of the wave front are modified. This method is generally used for investigations of deep layers including oil and gas deposits.
However, during the past several years, shallow reflection investigations became applicable in the area of geophysical engineering as well, thanks to significant resolution enhancements and the dynamic range of seismographs, e.g. the Terraloc Mark 6.
Seismic reflection may also be an independent geophysical engineering method, used for solving problems in geologic and hydro-geologic engineering practice and whenever it is necessary to supplement refraction investigations.

Seismic tomography is a method for defining 2D velocity distribution of artificially induced elastic waves. This method may be applied in different ways: between two boreholes, between terrain surface and borehole, and between two surfaces.
The seismic wave source and the receivers-geophones need to be in the same plane, which may have any spatial orientation.
After recording longitudinal and transverse (P and S) elastic waves, the spatial velocity distribution and other physical parameters are obtained by appropriate software and the process of inversion, and the data are then presented in the form of 2D sections as shown in the figure below. It is thus possible to identify and investigate minor changes in the composition of rock formations, such as fissures, faults between boreholes, caverns, etc.

Geoelectrical investigations are most frequently conducted in order to study the geologic composition and physical properties of rock formations, for solving problems in the course of structural and regional geological investigations, prospecting for metallic and non-metallic ore, and in geological and hydro-geological engineering practice.
Geoelectric methods are based on the difference between electrical properties of material. Electrical resistance varies for different materials, depending on several factors: mineral composition, moisture, ionic presence in water, primary and secondary porosity, temperature.
One of the electrical characteristics of investigated rock formations and media is the specific electrical resistance, or the capability to conduct electrical current in varying degrees. The numerical value of specific electrical resistance is based on a cubic meter of rock and expressed in Ohm. Electrical resistance of rock formations varies over a wide range, from a fraction of an Ohm to several thousand Ohm, providing significant possibilities to study rock formations in terms of the resistance paramete

The following geoelectrical investigation methods are used to address the above-mentioned issues:

Terrameter SAS 1000, a battery operated single-channel unit that measures three parameters: specific electrical resistance, induced polarization, and inherent potential. Terrameter SAS 1000 includes a PC compatible microcomputer.
Lund Imaging System is a multi-electrode system for automatic measurement of electrical resistance, with a high 2D and 3D resolution.

ERIGRAPH – allows geoelectrical probing data interpretation for the Vener electrode arrangement, in order to obtain pseudo sections, 1D Zohdy model, and 2D inverse model;




ES2DINV – allows automatic interpretation of data obtained by the Lund Imaging System and generation of 2D models (vertical terrain sections) for the specific electrical resistance (SER) parameter, taking into account the effect of terrain topography.








RES3DINV – a software package that allows 3D terrain modeling for the specific electrical resistance (SER) parameter, using data obtained by a special field procedure.