Theodor Krey

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Theodor Krey
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Latest company Prakla-Seismos

Theodor Krey (August 17, ​​1910-June 15 1993) was a German geophysicist noted for his work in many areas of geophysics including in-seam seismic channel wave studies in coal.

Biography Citation for the Maurice Ewing Medal

Contributed by Roland Marschall

The Society of Exploration Geophysicists in 1991 honors with SEG's highest award, the Maurice Ewing Medal, a scientist who, though having found his metier by accident, was able to combine the theoretical aspects of geophysics with the practical ones. In fact, this combination, in which the driving force was always well-balanced between theory and application, resulted in continuous contributions to exploration geophysics, spanning a time frame of roughly 55 years. The third important factor (without which no breakthrough is achieved) is creativity, and it can be claimed that Krey is a person of extraordinary creativity.

Honors and Awards

These aspects have been recognized in Germany, Europe and the US, resulting in the following well-deserved honors:

1988 Title of Dr.rer.nat.h.c. granted by the faculty of geosciences at Ruhr-Universitat Bochum, which (again) is their highest distinction
1988 EAEG Honorary Membership
1986 Honorary Member of the Hungarian Geophysical Society
1984 Renaming of the Rayleigh-channel wave into Krey-wave
1981 SEG Honorary Membership
1979 Conrad Schlumberger Award, EAEG's highest honor
1972 Title of professor granted by the senate of Hamburg
1969 EAEG President*
1952 SEG Best Paper Award

These awards have been given for two categories of reasons, i.e., either for a particular contribution or for overall recognition of the various innovative ideas of Theodor Krey. Here the SEG Best Paper Award resulted from a paper dealing with diffraction effects, the name Krey-wave was given as a recognition of Theodor Krey's in-seam seismics activities. (In that content it should be mentioned that Evison was honored in a similar way by renaming the Love-channel wave into Evison-wave.) The title professor was due to his teaching activity (topic: applied seismics) parallel to his main job at Prakla-Seismos.

Early Years and Education

Born on 17 August 1910 (Freiburg/Elbe), descending from craftsmen on his father's side and mariners on his mother's side, Krey almost had become a sailor, but financial grants by Bremer Stipendienverein (for the first semester) and the Franz Schutte-Stiftung (for the remaining semesters, fortunately for our profession) allowed him to attend the university in Gottingen, which was the mecca of science at that time, and partly that of Munich. These college years of 1928-32 were devoted to mathematics, physics, and geography. Among his academic teachers one finds famous names as Arnold Sommerfeld, Max Born, David Hilbert, Richard Courant, Edmund Landau, and Gustav Angenheister.

Professional Career

In this period he had the opportunity to experience a discussion on Alfred Wegener's theory of continental drift, where a famous geologist still denounced it. This event took place at a combined geologic/geophysical colloquium at about the time Wegener died in Greenland. In 1932 he became a teacher at secondary schools, but in 1936 he decided to join Seismos GmbH. After a short interruption caused by the Second World War, he started again and continued his career from party chief to supervisor and finally technical managing director at Seismos in 1954, i.e., after the death of his boss and friend, Dr. Luckerath. In 1963 Prakla and Seismos united, and as a consequence Krey also assumed responsibility for the whole scale of scientific supervision of the crews of both companies, including data acquisition, processing and interpretation. In this year he also was engaged as a Uno consultant for a short time in New York and Bolivia.

The latest course which he held in exploration seismics was in 1984 in Bahia, Brazil. Nowadays he is still asked for consultations from time to time, especially when problems related to the deep crust and to KTB (deep continental drilling) are discussed.

My first contact with Krey was in 1967, starting with the topic of undershooting, a method which continuously is in use since then, and which was subject to continuous refinement as well. Reviewing Krey's output, one should recognize that he is one of the few scientists who fortunately never specialized i.e., who was (and is) active in the fields of data acquisition, processing and interpretation, and thus never fell into the traps of playing the part of manager. He considered applied seismology as his great challenge, which resulted in numerous publications on topics as velocities (Dix-Krey formula), refraction effects, undershooting, 3-D seismics, anisotropy, vibroseis, resolution, S/N ratio improvement, and many more.

In 1980, co-authored with Peter Hubral, an SEG monograph was published, which is only No. 63 in the list of his publications[1].

The amusing aspect here is that Krey officially retired in 1975, but he continued his work and kept a close relationship to Prakla-Seismos and (after the take-over in 1991) to Geco-Prakla. We still have our weekly discussions in Hanover, and it is a great honor for me to congratulate Theodor Krey in the name of SEG on this well-deserved award.

Biography Citation for SEG Honorary Membership

From the beginning, his preferences were physics and mathematics. Nevertheless, he nearly became a sailor as there was no money for him to study. A last-minute scholarship paved the way for a 45-year career in applied geophysics. Forty-five years of tremendous creative power and range have now culminated with the bestowal of Honorary Membership in SEG.

Theodor C. Krey is not a member of the first generation of pioneers like Ludger Mintrop who created an essential instrument of applied geophysics for prospecting in our raw-material hungry world, and who heads the list of Honorary Members of SEG. Krey belongs to the second and third generations responsible for perfecting the art of exploration.

The path through life of seismologist Krey took an almost "classical course." After joining Seismos in 1936, he was soon promoted to party chief and then to supervisor.

In 1954 he was appointed a member of the board of directors. When the two German geophysical companies Prakla and Seismos united in 1963 he took over (in addition to his function as managing director of Seismos) scientific supervision of the survey crews and the interpretation department of the newly formed company. This supervisory activity, as well as a temporary function as UNO advisor, allowed him to become acquainted with many parts of the world. At the end of August 1975 after his 65th birthday, he retired but retained ties with the company as scientific advisor.

There is still a lot to be added. In 1965 he fulfilled his old wish to take a doctor's degree. Shortly afterward, Hamburg University asked him to lecture in geophysics. In connection with this activity, the university conferred on him the title of professor, which proved that he has always been prepared to pass on his knowledge and experience to others.

The EAEG, of which he was a founder, elected him president in 1957. In 1980 he was honored by the same society with the "Schlumberger Award 1979." In 1952 he had received the "Best Paper Award" from SEG, of which he has been a member for 26 years. This was for his paper, "The Significance of Diffraction in the Investigation of Faults."

In addition to SEG and EAEG, Dr. Krey is a member of numerous other scientific associations, including the Geophysical Union, Seismological Society, American Association for the Advancement of Science (AAAS) as well as several important German scientific societies.

The life work of Theodor C. Krey is reflected in numerous patents, in countless articles, papers and publications, internal technical-scientific notes, circulars, recommendations, and proposals. Selecting individual topics is particularly difficult. Associated with his name are refraction seismics (surely his first major topic), "seismic velocity" in all forms, detection of salt domes and their contours, and the investigation of that which lies underneath, particularly emphasized by the Schlumberger Award. Besides its general assertions, we find the sentence, "The complex problems related to deep salt dome basins havebeen given special attention, and his findings have enlarged our knowledge of this complicated problem." For the coal mining industry, he created "in-seam seismics." The first practical tests in the Ruhr district in 1952 were unsuccessful. But two years later, a breakthrough was achieved in a Saar mine. The channel waves postulated by Krey really did exist in coal seams.

Static and dynamic corrections became his specialty after the introduction of multiple coverage, to which he likewise dedicated comprehensive studies. He contributed to the Vibroseis technique and to data processing. All the same, he did not lose contact with the problems of field techniques: this is proven by his work on the filter characteristics of various transmitter and receiver configurations. A lifelong battle was fought for improvement of the signal-to-noise ratio and the suppression of multiples. 3-D seismic finally became the great challenge, including everything that goes with it: field geometry, corrections, migration, attenuation of multiples, and maintaining reasonable high resolution. Yet despite his love for theory and abstract mathematics, Theodor C. Krey remains closely tied to the practical aspects. He furnishes the theory as far as needed, and he also successfully applies it. The hurdle between the mathematical-physical model and geologic reality does not represent an insurmountable obstacle for him. This means he is not only a man of theory but also a man of practice. Some aspects of his practical and theoretical achievements are revealed in the book, Interval Velocities from Seismic Re?ection Time Measurements, which Peter Hubral and he co-authored as an SEG Monograph in 1980.

So much for the "balance" of his profession, which can only be viewed as provisional, for not one of his scientific projects is in any way regarded by him as being completed. When we ask ourselves what constitutes a personality of the described style, we must name everything that characterizes a great scientist: good judgment, reasoning power, knowledge, criticism, and skepticism concerning his own ideas, staying power, and diligence--and to the same extent, fantasy and intuition. These qualities have made Theodor C. Krey what he is and hopefully will be for a long time to come, not only for his "mother company" Prakla-Seismos, but also for our profession and science in general: an authority, a catalyst, and a driving force.

SEG Best Paper in Geophysics Award

Theodor Krey received the 1952 SEG Best Paper in Geophysics Award for his paper The significance of diffraction in the investigation of faults.[2]


  1. Hubral, Peter; Krey, Theodor (1980). Interval Velocities from Seismic Reflection Time Measurements. Society of Exploration Geophysicists. doi:10.1190/1.9781560802501.
  2. Krey, Theodor (1952). "The Significance of Diffraction in the Investigation of Faults". Geophysics (Society of Exploration Geophysicists) 17 (4): 843–858. doi:10.1190/1.1437815.


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