The Department of “Geophysics” is established as successor of the Geophysical Institute (http://www.geophys.bas.bg), separated by two Department “Geophysics” and “Seismology” within the newly created National Institute of Geophysics, Geodesy and Geography in 2010.
The Geophysical Institute was founded through the merger section of “Physics of the atmosphere and geophysics” at the Institute of Physics and “Seismological Service” at Geological Investigation Management in January 1960. The group “Physics of the ionosphere” from the Research Institute of Communications and the Geomagnetic Observatory “Panagurishte” led by the Ministry of Defence joined to the newly created Institute in 1961.
Creator, organizer and first director of the Geophysical Institute is Academic Lubomir Krastanov (1908- 1977). Today, several decades after his death, he remains one of the most famous names in Bulgarian Geophysics. He develops a model for the deposition of monovalent ions on the crystal substrate composed of divalent ions in his doctoral thesis. Academic Krustanov discovers with this scientific work a new mechanism for epitaxial deposition of thin films by condensation, known today as the “Mechanism of Krastanov- Stranski”. The quantitative theory of these processes is given for the first time precisely by Academician Krustanov. This issue is especially relevant today, when the deposition of thin metal or semiconductor layers widely used in the production of components for microelectronics and in modern nanotechnology. This work of Krustanov is one of the most cited research papers written in Bulgaria. Academic Krustanov has significant contributions to atmospheric physics, in particular to phase transitions of water in the atmosphere and cloud formation processes as he solves basic problems of condensation and crystallization processes in the atmosphere. Together with his collaborators Prof. Krustanov develop new theory of turbulence in the boundary layer of the atmosphere. This study describes fully the characteristics of turbulence in the surface layer and scientific results agree very well with experimental results. Publications on the subject are appreciated in the scientific community. Academician Krustanov is also Chairman of the Bulgarian Academy of Sciences during the period 1962 – 1968. The research activities of the Institute in this period, is focused on investigating a number of pure scientific and applied problems.
In 1959, the Research Institute of Communications under the leadership researcher Kyril Seraphimov bought the first station for vertical sounding in the ionosphere – IRX 59. This station won a gold medal at the World Electronics Exhibition in Brussels. The ionosphere station is installed in the courtyard of the Institute of Communications Dianabad area in the outskirts of Sofia (42 41′ N, 23 21′ E). A small house is built according all requirements for the operation of such equipment. The main antenna is 44 meters high and make possible to transmit and receive frequencies of about 1 MHz. This allows to be studied indirectly the lower ionosphere also – in particular the area D. The group of K. Seraphimov with ionosphere station and all staff joined the newly created section “Physics of the ionosphere” under the direction of Georgy Nesterov in 1961.
In 1961, the Institute starts activity in construction, development and improvement of the network of stations and observatories for gathering, storage and processing of information related to the natural mode of many geophysical fields in the country.
New automatic ionosphere station starts working parallel to the ionosphere station IRX 59 in 1966. The new station is installed in Tsarevo and a total sun eclipse is registered in May. Data collection from both stations helps for their calibration and data compatibility. A new ionosphere station KOS 89/2 is purchased and replace outdated station IRX-59 in 1989. KOS 89/2 is moved to Observatory Plan in 2006, where it works until now.
Another traditional field of the Department, initialized about forty years ago by its founder Dr. D. P. Zidarov, is methods for solving the inverse problems and numerical analysis of potential fields. The main investigations begun and the corresponding results have been obtained mainly under his scientific leadership. Methods for solving the inverse problems of the potential fields with elementary sources (positive and negative point masses, current loops, etc.) have been worked out. On the basis of these methods the distribution of gravity and geomagnetic inhomogeneities of a different type (local, regional and global) in the Earth can be effectively studied. The obtained solutions give an idea about the Earth’s inner structure and can be used when searching and studying mineral resources.
The Geomagnetic Observatory – Panagjuriste is a centre of measurements and registrations of the geomagnetic field in Bulgaria. It has been built in 1937 and was the first one on the Balkan Peninsula. In the course of more than 60 years there is a continuous registration of the variations of geomagnetic field and absolute measurements records. The processed data have been published in geomagnetic newsletters from 1956 to 1982. The data in digital form has been sent to the World Data Centres since 1983 until now.
Angel Venedikov initiates the study of earth tides in Bulgaria in 1961. He became a world-renowned scientist with his research and computing programs for the parameters of the tidal deformation of the Earth. His most important achievements are his mathematical methods for the analysis of these deformations, so-called “Venedikov method” and “Venedikov Filters” accepted and widely used by the international scientific community on earth tides. Angel Venedikov conducts also the first measurements of tides in Bulgaria.
Early paleomagnetic studies starts in 1965 by Prof. Peter Nozharov, founder of the Palaeomagnetic Laboratory at the Geophysical Institute. A number of paleomagnetic dating of intrusives of Maritsa intrusive zone and the Eastern Srednogorie, as well as volcanic rocks of the Rhodope Mountains, have been done. Archaeomagnetic research in Bulgaria starts in 1967. The founder of this field is Prof. Mary Kovatcheva. She starts accumulating data on the elements of the ancient geomagnetic field for the territory of Bulgaria by examining the remains of burned clay from archaeological sites. Due to her hard work many years, Bulgarian scientists support and enrich now the world’s longest Archaeomagnetic data with time period covering almost continuously the last 8000 years.
During the transition period after 1989, and by the end of the century, the main efforts are focused on the preservation and development of achievement with particular focus on ensuring the safe operation of the monitoring network of the Institute. Since 1997 has begun purposeful efforts for renovation and modernization of the institute monitoring network. As a result of international cooperation and with the support of the Ministry of Education and Science – Project EMIRA, apparatus in the Geomagnetic Observatory are fully renovated and equipment is purchased to build a network for measuring biologically active ultraviolet radiation and total ozone concentration in the atmosphere. The equipment in the Palaeomagnetic Laboratory is modernized with the support of the same project, allowing carry out modern and multilateral magnetic studies related to environmental protection and Paleoclimate reconstruction.
In conclusion can be said that Department of “Geophysics” is a modern research centre that has a qualified personnel and modern equipment. The Geophysical Institute has published its Annuals with the results of the latest scientific research from its inception. “Bulgarian Geophysical Journal” has been issued since 1975 and has been printed in English since 1999.