Physical fields caused or changed by the natural environment of the planet are called geophysical fields (GF). Their spatial distribution and change in space and time depend on both the presence and power of their sources and on the structural peculiarities of the natural environment and its dynamics under the influence of natural and technogenic factors. Knowledge of the GF present state and the character of its transformation is necessary for an insight into natural processes that influence the life of people and economy of the country, for long-term socioeconomic planning, rational land use, purposeful mineral explorations, as well as for prediction of dangerous processes.

The Earth’s gravitational field, or the field of gravitational force, is a force field caused by the Earth’s attraction and the centrifugal force generated by the planet’s rotation around its axis. It divides conventionally into anomalous and normal. The anomalous gravitational field (AGF) reflects the peculiarities of the Earth’s figure and structure of its interior. In the territory of Ukraine, the AGF changes within a wide range, reflecting, above all, the character of the distribution of rock density in the earth’s crust and upper mantle. On the map included in the atlas, the distribution of the abnormal gravitational field is marked by isoanomalies, i.e., lines connecting points of equal anomaly.

The map of the abnormal density of the earth’s crust and the upper mantle is based on the gravitational simulation of gradient-layered three-dimensional deep-seated structures using the data on the abnormal gravitational field, results of deep seismic sounding (DSS), experimental correlation dependences between the specific density of crystalline rocks and the velocity of seismic waves propagation at different pressures and temperatures. Owing to the tendency to the isostatic balance of separate blocks and their aggregates under the heavier blocks, the subface of the earth’s crust dips, and under the lighter, rises.

The thermal field also provides important information on the structure and dynamics of our planet. The thermal state of the earth’s crust is characterized by the density of a heat flow coming from the earth’s interior and dispersing from its surface, as well as by the change of temperatures with depth.

The major role in the formation of a heat flow is played by the energy of disintegration of long-lived radioelements (uranium, thorium, potassium), the maximum concentration of which is observed in the crustal rocks, the primary energy of the Earth, and the energy of physicochemical processes in its interior. An important role is also played by conditions of heat transport that change substantially with depth and laterally. The leading role in the formation of positive geothermal anomalies belongs to active tectonic and magmatic processes that entail the release of a large amount of thermal energy.

The density of the heat flow is a quantity of heat released from the interior to the surface in a unit time per unit area. It is measured in mW/m² and is defined as a result of multiplication of the geothermal gradient in a certain interval of depths by thermal conductivity of rocks of this interval. In the territory of Ukraine the heat-flow density varies from 25–30 mW/m² to 100–110 mW/m². Temperatures at a depth of 1 km vary from 20 to 70 °С and at a depth of 3 km, from 40 to 135 °С. The distribution of heat flows is closely connected with the peculiarities of the geological development of regions and their tectonics.

The abyssal heat flow (DHF) is an observed heat flow corrected with consideration for numerous near-surface effects: paleoclimate, groundwater motion with a vertical component, geological structures, which bring about the non-horizontal bedding of rocks with different thermal conductivity, young thrusts, and the accumulation of young sedimentary deposits. The DHF map demonstrates the distribution of its background (35–50 mW/m²) and anomalous (60–130 mW/m²) values in the territory of Ukraine.

The heat energy of the Earth is a geoenergy resource. Based on the DHF data, the map of density of geoenergy resources represented in the atlas is made in tons of coal equivalent per square metre, which can be produced by the water geocirculating system with the temperature (T) of the carrier no less than 60 °С and its return into the interior with T ~20 °С. The total geoenergy resources of Ukraine (assessed to date) are about twenty times larger than all resources of combustibles in its territory. In some areas they reach 10 tons of standard coal per square metre, which exceeds energy resources that can be extracted from a large oil or gas field. For the present, geoenergy resources, suitable for practical use by generating steam (electrical energy) without additional heating, have been explored only in Zakarpattia and on very limited territories in the Crimea.

The magnetic or geomagnetic field is a geophysical power field caused by electromagnetic processes in the earth’s core (main, or normal, field), in the upper strata of the ionosphere (variations of the geomagnetic field), and the magnetization of rocks of the earth’s crust. The latter factor forms the anomalous magnetic field that reflects the presence of rocks with different concentration of magnetic minerals in the earth’s crust. It is calculated by substracting the intensity of the normal field and its variations from the intensity of the total geomagnetic field. The normal field has no exact analytical mapping. To describe it several approximating models are used, one of them is given in the atlas.

The anomalous magnetic field in the territory of Ukraine is greatly differentiated and consists of regional and local components that differ in transverse dimensions of anomalies and the depth of location of their sources.

The regional component of the field represented on the map Long Wavelength Magnetic Anomalies is the result of the composition inhomogeneity of the lower part of the earth’s crust and the relief of the bottom of the magnetoactive stratum, which can be identified with the bottom of the earth’s crust (the Mohorovicic Discontinuity) or with the isothermal surface of the Curie temperature of magnetite, the main carrier of rock magnetism. It reflects regional features of large geostructures.

A local component of the anomalous magnetic field is formed under the influence of magnetized rocks of the upper part of crust and reflects its composition and structure. This magnetic field component is used as one of the important sources of information for geological mapping of rocks, study of fold and fault tectonics, tectonic zoning, and in the complex with a regional component and other geophysical data – for study of correlation of near-surface and deep seated structures of the lithosphere, for construction of non-uniformly scaled three-dimensional models of geological environments, which are used to estimate the prospects of geological structures for various minerals.

The magnitotelluric field of the Earth is a natural electromagnetic field caused by ionospheric-magnetospheric system of currents. This field is one of the important sources of knowledge of the modern geological structure, tectonic processes, geodynamics, and fluid regime of the earth’s crust and mantle. Electrical properties of rocks are closely connected with temperature and fluid regime of the interior, chemical composition of rock minerals with C, S, and Fe and other metals in their structure, the level of mineralization of juvenile waters, and the presence of molten rocks in the crust and mantle. The atlas maps The Earth’s Crust Electrical Conductivity and The Upper Mantle Electrical Conductivity are made in the units of conductivity – siemens (S), basing on the analysis of the observed magnitotelluric field with the use of methods of three-dimensional film simulation of electromagnetic fields. Anomalies of electrical conductivity stand out against a background of the 'normal' generalized geoelectrical section of the East-European platform, which is characterized by specific electrical resistance (in Ohm·m): 1000, 600, 250, 100, 50, 20, 10, 5, 1, 0.1 in layers of the geological environment with thickness of (in km): 40, 50, 70, 80, 100, 120, 160, 200, ∞. The value of longitudinal electric conductivity of the environment film was taken equal to 10 s.

To study the abyssal structure of the Earth: the geometry and location of major tectonic boundaries and distribution of physical parameters of the geological environment one more type of GF – the seismic field – is used. It is observed as mechanical vibrations on the ground surface or in mines, caves, adits, and wells. Vibrations are generated by seismic waves (longitudinal, transverse, surface, channel) that travel from a source fading away, reflecting, breaking, and re-radiating into other types on inhomogeneities of the geological environment. Depending on the source, a seismic field may be natural or artificially generated.

Studies of artificial seismic fields generated by special explosions and observed along geological profiles made it possible to receive unique data on the internal structure of the Earth, which are used for exploration activities and solution of a number of other important geologic-geophysical problems. The atlas represents profiles of the earth’s crust and lithosphere through major tectonic structures in the territory of Ukraine.

1. The observations on the geotraverse of the deep seismic sounding (DSS) Holovanivs’k – Kirovohrad – Taganrog that intersects near latitudinally the eastern and central parts of the Ukrainian Shield are made by means of continuous profiling, with the use of a system of interrelated head and reflected wave time-distance curves. The presented model elucidates velocity characteristics and the abyssal framework of the Archean-Proterozoic structures of the shield.

2. The geotraverse Black Sea – Baltic Sea in the territory of Ukraine is more than 900 km long. It traverses the paleozoic Scythian plate and the pre-Cambrian Ukrainian Shield. The velocity model is built on the basis of the two-dimensional numerical simulation of the wave field received by the DSS method.

3. The DSS profile Poltava – Sverdlovs’k goes lengthwise the Dnipro-Donets’ aulacogene.

4. Deep seismic investigations of the profile Berehove – Dolyna – Vyshnivets’ – Shepetivka – Chernihiv elucidated the framework of tectonic structures of different age and genesis: the Zakarpattia (Transcarpathian) Mesozoic-Paleogene flexure, the Carpathians that are one of Europe’s major alpine orogenes, and the Archean-early-Proterozoic Ukrainian Shield.

5. The DSS profile Putyvl’ – Kryvyi Rih connects ultradeep boreholes (UDBH) 8 and 9. In its southern part it goes along Kryvyi Rih – Kremenchuk submeridional early-Proterozoic protogeosyncline, and in the northern, traverses slantwise the Dnipro-Donets’k late Proterozoic-Devonian paleorift of the north-western strike.

A large volume of seismic profiling (more than 10 ths km) for investigation of the earth’s crust and lithosphere structure was carried out in the territory of Ukraine. The map of the Mohorovicic Discontinuity (The Moho) presented in the atlas is based on these data. The name ‘discontinuity’ is conventional, as actually this is a thick transitional zone between the earth’s crust and the upper mantle characterized by a complex structure and alternation of thin layers with increased and decreased seismic wave velocity.

The thickness of the earth’s crust within the borders of Ukraine varies in a very wide range – from 25 to 65 km. The maximum thickness of the crust is fixed under the Carpathians (65 km), the mountainous Crimea (up to 60 km), and the Ukrainian Shield (Odesa-Yadlivka, Kryvyi Rih-Krupets’, and Orikhiv-Pavlohrad early-Proterozoic geosynclinal zones – 50–60 km). The minimal thickness of the earth’s crust is observed in the region of the Zakarpattia (Transcarpathian) flexure (25 km), under the Dnipro-Donets’k aulacogene (30–35 km), in the Ukrainian Shield, in the regions of the Zaporizhzhia middle massif (25–30 km), the Kirovohrad protoplatform block (35 km), and in the territory of the Black Sea depression (25–30 km).

Natural seismic fields caused by sources of local and strong remote earthquakes, in view of their great hazardous, should be taken into account when constructing dwellings, important facilities, and objects of high ecological and man-caused risk. Earthquakes are caused by modern tectonic activities of geological structures. The distribution of earthquakes of different magnitude in time and space is called seismicity.

In the territory of Ukraine a high level of seismicity is observed in two major seismic regions: Carpathian and Crimean-Black Sea.

The seismicity of the Carpathian region is determined by earthquakes with epicenters in Zakarpattia (Transcarpathians), the Carpathians, Peredkarpattia (Forecarpathians), and on the adjacent territories of Poland, Slovakia, Hungary, and Romania. Zakarpattia (Transcarpathians) is the most seismic-active region.

In the territory of western regions of Ukraine (for the period from the 17th century to the present time) earthquakes are characterized, for the most part, by the depth of sources (h) in 2–10 km and magnitudes (M)<5.5. Due to the small depth these earthquakes cause local effects on the surface of the ground with the intensity up to 7–8 degrees on the MSK-64 scale. The same vibrations are felt in Transcarpathians from deeper (h=35 km) and prepotent (M=6.8) earthquakes with epicenters in Romania (Piscolt) at a distance of ~60 km from the frontier of Ukraine. In the territory adjacent to Peredkarpattia (Forecarpathians) the strongest earthquake of those reliably described was recorded in 1875 in the vicinity of Velyki Mosty, L’viv Oblast’. It had a magnitude of 5.3 and the depth of the source 19 km, and was felt in the epicentral zone with the intensity of 6 degrees. In Chernivtsi the intensity of vibrations reached 3 degrees.

Undercrust earthquakes from the Vrancha zone in Romania have an impact on a large part of Ukrainian territory. The sources of earthquakes that can cause significant macpinkismic effects in the territory of Ukraine are located in the mantle at a depth of 80 to 190 km. The maximum magnitudes of earthquakes in this zone reached 7.6. Due to the great depths of the sources and their magnitudes, the earthquakes of the Vrancha zone appear on a vast territory: from Greece in the south to Finland in the north. The map of the epicentres represents earthquake sources of the Vrancha zone with magnitudes of more than 3.5 beginning from the 11th century. The isoseists of the most severe earthquakes in the Vrancha zone in the past two centuries have been reliably defined.

The seismicity of the Crimean-Black Sea region is determined by earthquake sources located in the Black Sea water area, near the Southern Coast of the Crimea. They are characterized by the greatest in the territory of Ukraine magnitudes (up to M=6.8). On the epicentres map the earthquakes in the Crimea are represented with M>2, for the observation period from the 1st c. BC to the present time. On the flat part of the Crimea and in the Sea of Azov water area the earthquake sources with M>1 are shown.

In the platform part of Ukraine only several perceptible local earthquakes are known. Their sources were located in the earth’s crust, and therefore the seismic effect was of a local character. The intensity of seismic shakes in the epicentral zone reached the magnitude of 6–7 degrees. The train of aftershocks of an earthquake with the intensity of seismic quakes 6 degrees on MSK-64 scale that took place on January 3, 2002, in the vicinity of the settlement of Mykulyntsi, Ternopil’ Oblast’, demonstrated once again the presence of the considerable seismic activity of the platform tectonic structures in the territory of Ukraine.

The level of hazard the earthquakes can entail is shown on maps of the general seismic zoning (GSZ) in degrees of MSK-64 macpinkismic scale. These maps are used for long-term socioeconomic planning, rational land use, taking administrative and technical decisions on securing stable operation of existing structures and siting of new ones (hydroelectric power plants, nuclear power plants, pipelines, etc.). In seismic regions of Ukraine, three probabilistic maps of GSZ-2004 designated as A, B, C, regulate the design, prospecting, and construction works. They show values of the intensity of seismic shakes that can occur once in 500, 1000, and 5000 years, and, accordingly, can be exceeded with the probability of 10%, 5%, and 1% in the coming 50 years.

Maps of seismic microzoning (SMZ) show the predictable increase in seismic intensity in different areas of the territory represented relatively on the GSZ maps. An increase can be positive or negative depending on the local soil conditions, relief, and presence of tectonic faults. When making SMZ maps the data of engineering-geological investigations are used, as well as the data of macpinkismic examinations of earthquake aftermaths, instrumental observations of seismic fields of earthquakes, explosions, natural and artificial micpinkisms. The SMZ maps are used for planning the development of inhabited localities, provision of stable operation of existing structures and design of new ones.

The geophysical fields maps presented in the atlas and maps and schemes made on their interpretation, which represent the deep structure of the lithosphere, dynamics of tectonic structures, danger related with earthquakes, crypt movements, landslides, and subsidences, are an important instrument for knowledge of the deeper structure of the planet, purposeful search for mineral deposits, and protection of the population, dwellings, and important structures from dangerous endogenous processes and secondary engineering-geological phenomena associated with them.