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Home > Science and research > Structure, Composition and Evolution of the Earth's Crust > Geophysics

Geophysics

Geophysics belongs to a group of natural sciences focused on the study of the Earth. Geophysics examines physical phenomena on the Earth's surface, in the interior of the Earth, and in a part of the interplanetary space that we can understand to be close to the Earth.

Applied geophysics

Applied geophysics refers to the part of geophysics that deals with the study and measurement of both natural and artificially induced physical phenomena in the Earth's crust and the upper mantle of the Earth. The results of these studies and measurements are applied in solving geological problems, monitoring environmental changes, surveys for mineral deposits, construction, archaeology etc.

Geophysical methods are divided into several basic groups according to the physical principle, the character of the observed physical phenomenon or field and the method of measurement:

  • the rate of elastic wave propagation in various rock environments is dealt with by seismics;
  • the gravity field of the Earth studies gravimetry;
  • the Earth's current magnetic field is the subject of magnetometry,
  • a summary of the effects of the magnetic field that existed on Earth in the geological past describes paleomagnetism;
  • geoelectrics is concerned with the study of electric and electromagnetic fields;
  • radioactivity of rocks and the environment is investigated by radiometry;
  • Earth's thermal field and heat flux studies geothermics;
  • well logging deals with the measurement and interpretation of all the above physical phenomena and fields in boreholes
  • the physical properties of rocks such as specific weight, magnetic susceptibility and anisotropy, natural radioactivity, etc. are investigated by petrophysics, which is also considered to be one of the methods used in applied geophysics.

Applied geophysics is used in geological mapping (study of geological structure of the upper layers of the Earth's crust, differentiation of different types of rocks, geological structures, and tectonics). It is also used in economic geology by observing the anomalies of the geophysical fields of the Earth (as Earth's magnetic field anomalies for the survey for iron ores, gravity field anomalies in hydrocarbon survey, elastic wave velocity anomalies when studying Earth's crust and survey for mineral deposits, especially oil and gas). In hydrogeology it may be used for mapping of permeable layer, faults, monitoring of groundwater contamination, utilization of geothermal energy. In engineering geology it is used for determination of depth of non-weathered subsoil and quality of rock environment, mapping of weakened zones and cavities and control of slope stability. In environmental protection and construction it can determine radioactivity of building materials, determination of radon risk, it helps with the landfill subsoil research, localization of unexploded ammunition, search for archaeological objects threatened by construction, etc. The methods used by applied geophysics are also used in archaeological research, especially observation of anomalies of the Earth's magnetic field - magnetometry and geoelectric methods.

Geophysical data

The project CzechGeo / EPOS addressed the access to geophysical data as a specific priority topic under the guidance of the Czech Geological Survey. In accordance with the current needs of national and international activities (European INSPIRE directive, EPOS project, IAGA), available data is being organized, consolidated and harmonized according to national and international standards. The main goal of the activity is to make this data available for the researchers and for the professional public. This includes a structured metadata description of the relevant data and the launch of web services for viewing and possibly downloading data.

Map application Geophysical measurements displays layers, thematically divided according to the geophysical methods used for the data acquisition. The map application contains the geophysical measurements paid by the Czech state, carried out mainly by former company Geofyzika Brno. Application displays the following map layers: seismic (2D reflection seismic and well shoots), vertical electric sounding (polygons, lines, points) and localization of the geophysical surveys on the territory of the Czech Republic (both regional and local). New map layers on gravimetry, airborne geophysics (magnetometry, spectrometry and radiometry) and petrophysics have been incorporated as well.

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Gravimetry

Gravimetry examines the gravitational force of the Earth, which is called gravity, and is the result of the gravitational force of the Earth and the centrifugal force given by the Earth's rotation. The gravity is proportional to the gravitational acceleration, which can be measured on the Earth's surface, for example, by gravimeters. The distribution of gravity acceleration on the Earth's surface is not regular; local differences in the measured acceleration values, called anomalies, provide information about the different densities and thicknesses of the rocks below the Earth's surface.
Dataset information

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Seismics

Seismic methods study the elastic waves produced by earthquakes or artificially induced shocks. Exploratory seismic examines the geological structure of the surface of the Earth (Earth's crust) and uses controlled launches and vibrations. Seismic methods, especially reflective methods, are used in line (2D) and surface design (3D) very often in searching for crude oil and natural gas deposits.
Dataset information

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Magnetometry

Magnetometry measures the Earth's magnetic field (geomagnetic field), which is created primarily in the Earth's interior, at the interface between the mantle and the core. Another source, near the surface, are rocks containing magnetic minerals. Measured local differences in the geomagnetic field indicate the presence of these rocks with a higher content of magnetic components that can form deposits, such as iron ores.
Dataset information

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Radioactivity and spectrometry

The rocks of the Earth's crust contain radioactive isotopes of some elements; these are mainly isotopes of uranium 238U, 235U, thorium isotope 232Th and potassium isotope 40K. Radiometry is the method that deals with measurement of radiation of this natural radioactivity on the Earth's surface. Depending on the amount of radiated energy and the concentration of isotopes, it is possible to determine the composition of rocks below the surface and to indicate the risk of releasing hazardous radioactive gas of radon.
Dataset information

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Geoelectrics

Geoelectrics is one of the youngest geophysical disciplines. It is characterized by a large number of partial methods, many of which have many modifications. Using geoelectric methods we can differentiate rocks according to resistivity, permittivity and polarizability. We simply divide the methods into DC (resistance methods), electrochemical (using natural fields of filtration and diffusion character around natural conductors) and electromagnetic (based on the laws of electromagnetic induction).
Dataset information

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Well logging (Borehole geophysics)

Logging methods, also known as geophysical measurements in boreholes, use the principles of other geophysical methods to measure along the borehole. The so-called logging probes are used for the measurement and the measurement results are logging curves (measured value depending on the borehole depth). Logging methods are intended mainly for determination of rock environment, hydrodynamic properties and technical condition of well.
Dataset information

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Petrophysics

Petrophysics deals with the determination of physical properties of rocks taken on the earth's surface or samples from drill cores. These are scalar, so-called “substance” parameters (volume and mineralogical density, porosity, magnetic susceptibility, natural radioactivity of rocks) and directional parameters (magnetic anisotropy, elastic wave velocities, resistivity, etc.). These data form the basis for the interpretation of gravity, magnetometric and radiometric measurements.
Dataset information

icon of linksLinks

Geophysical measurements

Map application - gravimetry, seismic, VES, geophysical surveys

Borehole surveys

Map application - drill logs (Czech only)

Map archive

Map application - maps from the Czech Republic (Czech only)

Geophysical archive

Unpublished reports from the Czech Republic and abroad (Czech only)

icon On-line applications
Geophysical surveys

WMS service (Czech only)

How to get data?

Information about provision of the CGS geological data, price list, contacts...

CzechGeo / EPOS

System of geophysical observations in the CR

EGDI

European Geological Data Infrastructure

icon of contactsContacts

Czech Geological Survey
Leitnerova 204/22
602 00 Brno
phone: +420543429205
fax: +420 543 212 370
eva.hudeckova@geologycz
Czech Geological Survey
Leitnerova 204/22
602 00 Brno
phone: +420543429288
fax: +420 543 212 370
vladimir.kolejka@geologycz