User:MHaeusler/sandbox/Evsey Iosifovich Galperin

Evsey Iosifovich Galperin
Born	31 October 1920 Uman, Ukraine (USSR)
Died	20 October 1990
Citizenship	USSR
Known for	Symmetric triaxial seismometer design (Galperin configuration)
Scientific career
Fields	Geophysics, Seismology
Institutions	Institute of Earth Physics of the USSR Academy of Sciences

Evsey Iosifovich Galperin (31 October 1920 in Uman (Ukraine, former USSR) – 20 October 1990 in Moscow) was a Sovjet seismologist and professor at the Institute of Earth Physics of the USSR Academy of Sciences. He was inventor of the symmetric triaxial seismometer design, today known as the “Galperin configuration”.

Life and scientific career

Evsey Galperin was born on 31 October 1920 in Uman (Ukraine, former USSR) as one of eight children in a jewish family as the son of Anna Markovna and Joseph Iosifovich. The family moved to Moscow in 1934, where he studied at the Moscow Geological Exploration Institute from 1938 to 1949, specializing in geophysics.

In 1941, Galperin joined the red army in World War II and fought with the Orenburg cossack cavalry regiment at the south western and Bryansk front. From 1942 to 1944, he was a cadet at the Leningrad topographic school. He was sent to the 2^nd Ukrainian front with the rank of a junior lieutenant for photo reconnaissance of the enemy’s front line for which he was awarded with the order of the red star in 1944. He was demobilized in September 1945 in Vienna. Galperin also holds the Order of the Patriotic War (2^nd degree) and the Order of the Badge of Honor.

After the war, Galperin finished his studies and started his scientific career as a junior laboratory assistant at the Institute of Earth Physics of the USSR Academy of Sciences, where he later pursued his doctoral studies and became professor. He married Rimma Mikailovna in 1962 with whom he had two children, Adam (*1962) and Sasha (1963).

Galperin introduced the symmetric triaxial seismometer design, which became widely used in exploration geophysics and seismology. The symmetric triaxial design is commonly known as the “Galperin configuration”, named after his inventor. Galperin also contributed significantly to the development of the Vertical Seismic Profiling (VSP) technique, which found little application outside the Sovjet union before mid-1970s but became a standard method in exploration seismology worldwide.

Evsey Galperin became ill during the 1990 annual convention of the Society of Exploration Geophysicist (SEG) in San Francisco. He returned to Moscow and died less than a month later.

The Galperin configuration

Common triaxial seismometers provide signal outputs in three orthogonal axes oriented towards East-West (E), North-South (N) and up-down (Z), i.e. in the Cartesian coordinate system. In contrast, the Galperin configuration consists of three orthogonal axes (U, V, W) that are oriented at precisely the same angle with respect to the horizontal plane (α=35.26°). The projection of all three axes onto the horizontal plane are all separated by 120°, which results in the "symmetric triaxial" design. The recordings acquired with the Galperin configuration are brought to the Cartesian coordinate system by the following coordinate transformation, where β=30°:

${\begin{bmatrix}E\\N\\Z\end{bmatrix}}={\begin{bmatrix}-\cos \alpha &\cos \alpha \sin \beta &\cos \alpha \sin \beta \\0&\cos \alpha \cos \beta &-\cos \alpha \cos \beta \\\sin \alpha &\sin \alpha &\sin \alpha \end{bmatrix}}{\begin{bmatrix}U\\V\\W\end{bmatrix}}$

A main advantage of the Galperin configuration is that all three receivers have identical orientation with respect to the vertical axis and, thus, have idential instrument responses. Another advantage is the ability to build smaller packages (i.e. instruments) compared to the Cartesian orientation, which makes the Galperin configuration especially applicable for borehole installations. Other benefits of the Galperin configuration include easier distinction between external and internal noise sources and the fact that the configuration is not sensitive to rotation around the vertical axis. However, the main drawback of the configuration is that all input vectors are linked by the rotational matrix, which causes failure of the entire system when one of the three sensor is malfunctioning. In the Cartesian configuration, for example, both horizontal components still provide useful data in case the vertical (Z) component failes.

The Galperin configuration found wide application in seismometer design, including models for borehole, ocean bottom, and vault installations. The Galperin configuration can also be applied at the source side to simulate three-component seismic sources

Publications

• Galperin, E. I., 1955, Azimuthal method of seismic observations, Gostoptechizdat, Moscow, 80.
• Galperin, E. I., 1974, Vertical Seismic Profiling. Special Publications, Society of Exploration Geophysicists, 12, Tulsa
• Galperin, E. I., 1984, The Polarization Method of Seismic Exploration. Solid Earth Sciences Library, Springer, doi: 10.1007/978-94-009-7091-5
• Galperin, E. I., and Kennett, Peter. 1985, Vertical Seismic Profiling and Its Exploration Potential. Modern Approaches in Geophysics, 1, Springer, doi: 10.1007/978-94-009-5195-2
• Galperin, E. I., Nersesov, I. L., and Galperina, R. M., 1986, Borehole Seismology and the Study of the Seismic Regime of Large Industrial Centres. Modern Approaches in Geophysics, 2, Springer, doi: 10.1007/978-94-009-4510-4