Sabba Stefanescu

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Sabba Stefanescu
Sabba Stefanescu headshot.png
Membership Honorary Member


Sabba S. Stefanescu (July 20, 1902 - April 15, 1994) was a Romanian geophysicist who pioneered magnetic methods for mining applications.


Memorial

Contributed by Dorel Zugravescu and Misac Nabighian

Originally appeared in:

Graebner, R., Levshin, A., White, J., Robertson, H., Zugravescu, D., Nabighian, M., Ringstad, C., Troost, K., and Free, R. (1994). ”Memorials.” The Leading Edge, 13(7), 786–788.


Sabba S. Stefanescu, honorary member of SEG, died 15 April 1994 after a short illness. With his passing, the geophysical community lost an outstanding pioneer, one who contributed immensely to the development of the nascent techniques of electrical methods of exploration. Stefanescu was born in Bucharest, Romania on 20 July 1902 into a family of distinguished intellectuals. After graduating with honors from a prestigious French institution, the Advanced Mining School, and after a brief stint in Romania as a mining engineer, he was offered the opportunity of specialization in Paris with the Schlumberger brothers. The well known “Stefanescu’s kernel” (associated with the theoretical calculations of DC resistivity curves over a stratified earth) was developed during this period and was published in a now classic paper. Modem concepts regarding current channeling can also be found in this paper.

During this period Stefanescu also developed exact formulae for calculation of the DC magnetic field of a grounded wire, which later led to development of the magnetometric resistivity method (MMR). He also established formulae for the “loop” method which allows, on the basis of electrical anisotropy, determination of the position of dipping layers under overburden cover.

After returning to Bucharest, Stefanescu resumed his activities at the Geological Institute and was instrumental in implementing various geophysical techniques in Romania. In 1950 he was appointed head of the first chair of geophysics in Romania. Practically all Rumanian geophysicists, as well as countless foreign-born geophysicists who have been his students, fondly remember the clarity of his lectures and his constant inspiration and encouragement to use physical intuition in solving difficult theoretical problems.

During this period, Stefanescu developed the elegant theory of “alpha centers” which allows a quick and simple 3-D interpretation of resistivity, IP, and MMR data. In addition, as a hobby, he did extensive research on the theory of magnetic field lines of filiform electric current configurations and established that, under certain conditions, minute changes in the relative positions of the current filaments can lead to dramatic changes in the shape and distribution of their magnetic field lines. Couldn’t geomagnetic reversals be explained by just such a process?

Sabba S. Stefanescu Stefanescu received numerous awards for his accomplishments. His international scientific prestige led to election in 1946 to the Romanian Academy of Sciences. He was the unique member of this prestigious institution to survive all reorganizations in both the communist and postcommunist periods. He was president of the Geology, Geophysics and Geography Section of the Academy, president of the Rumanian National Committee of Geodesy and Geophysics and honorific president of the Romanian Geophysical Society.

Sabba Stefanescu was a warm person with a friendly smile. He was a brilliant conversationalist, and an avid reader who particularly enjoyed reading philosophy. His students respected and idolized him. He was and will always remain our beloved professor. He was a true giant and will never be forgotten. He is survived by his son, Ion Sabba Stefanescu, a nuclear scientist now residing in Germany.


Biography Citation for SEG Honorary Membership

Although living far apart, the authors of these lines had cause for celebration when the almost half century of an oppressive communist regime came to an end in Romania, the country of our birth. Today we are happy to celebrate the awarding of SEG Honorary Membership to Professor Sabba Stefanescu, our teacher and mentor for almost four decades. In making this selection, SEG has not only acknowledged the important accomplishments of a distinguished scientist but has at the same time also emphasized the universal nature of our profession.

Sabba Stefanescu, born in Bucharest on July 20, 1902 into a family of distinguished intellectuals, was the third son of Professor Sabba Stefanescu, a corresponding member of the Romanian Academy of Sciences. During World War I, his father was sent by the Romanian government on a diplomatic mission to France. He managed to arrive, with his family, in 1917 after a perilous journey across revolution-torn Russia, across the Arctic Ocean and finally England. In 1923, Sabba Stefanescu graduated with honors from one of the most prestigious French technical institutions, the Advanced Mining School.

Back in Romania, he worked underground for one year as a mining engineer before health problems forced him to abandon his chosen profession. In 1927, he joined the prospecting section of the Geological Institute of Romania as a researcher, and quickly distinguished himself. As a result, the academician Ludovic Mrazec, undisputed head of the Romanian Geologic School, offered him the opportunity of specialization in Paris with the Schlumberger brothers. The well known "Stefanescu's kernel" (associated with the theoretical calculations for DC resistivity curves over a stratified earth) was developed during this time.

In the same period, he helped develop the first correct theory of the electromagnetic response of a low frequency dipolar source, which helped establish the nascent electromagnetic methods of exploration. Modern concepts regarding current channeling can be traced back to this contribution.

Also in the same period, Stefanescu established the theory for the calculation of the DC magnetic field of a grounded wire, which is now the basis of the magnetometric resistivity method. Before returning to Romania, he established the formula for the "loop" method, which allows, on the basis of electrical anisotropy, the determination of the position of dipping layers under overburden cover.

In Bucharest, Stefanescu resumed his activity at the Geological Institute and was instrumental in implementing various geophysical techniques in Romania. In 1952 he was appointed as head of the first Chair of Geophysics in Romania, with the primary duty of delivering lectures on electrical methods of exploration. Practically all Romartian geophysicists have been, at one time or another, his students. The clarity of his lectures and the constant encouragements to his students to use physical intuitionto solve difficult problems have been and continue to be an inspiration.

During this period, Stefanescu established the elegant theory of alpha centers for simple three-dimensional interpretation of resistivity, induced polarization and magnetometric resistivity anomalies. In addition, as a hobby, he did extensive research on the theory of magnetic field lines of filiform electric current configurations and established that, under certain conditions, minute changes in the relative positions of the current filaments can result in dramatic changes in the shape and distribution of their magnetic field lines. It is not unreasonable to postulate that such results might explain the physical mechanism of geomagnetic field reversals.

He was elected corresponding member of the Romanian Academy in 1950 and a full member in 1963. He is the president of the Geonomical Section of the Academy, president of the Romanian National Committee of Geodesy and Geophysics, and honorific president of the Romanian Geophysical Society.

At 88 years of age, Sabba Stefanescu still astonishes everybody by his amazing spiritual youth, by the youthful curiosity with which he looks at all aspects of life, and by his overwhelming optimism and vitality.