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- Volume 4, Issue 4, 1956
Geophysical Prospecting - Volume 4, Issue 4, 1956
Volume 4, Issue 4, 1956
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THE TECHNICAL‐ECONOMIC ASPECTS OF AUTOMATIC DATA REDUCTION*
More LessAbstractThe background of automatic data processing as well as other improvements in prospecting methods is almost certainly economic. Consciously and intentionally or intuitively and even subconsciously, economic forces are the drive for improvements.
Automatic processing can contribute to the increasing utility of seismic data. Reduction in the amount of routine work will permit talented people to utilize their time creatively on the more difficult problems. At the same time automatic reduction will provide for a greater volume of work. These two aspects will probably provide the first effective pressure for a high degree of automation.
It is to be expected, however, that the ultimate and greatest value will be better interpretation; possibly more detail, possibly clearer more definitive interpretation, possibly both.
Time concepts in the processing of seismic data are, of course, vital; either in simple time corrections of either static or dynamic nature or in treatment of signals in the time domain.
Much development work is needed before these advantages can be realized. Principal development needed is an increase in dynamic range in the overall system.
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SCALE MODEL SEISMIC EXPERIMENTS
By S. H. HALLAbstractAn experimental arrangement is described using an electric spark as source and barium titanate as a detector. Model experiments were made in water with the source mounted above the surface. The effect on the pulse shape on transmission through the air‐water interface and the change of pulse shape with depth were investigated. A number of profiles are presented of reflections from a slate slab immersed in the water with different arrangements of the model and detector.
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THEORETISCHE FRAGEN ÜBER BÜNDELUNG VON GEOPHONEN BEI UNTERTAGE‐MESSUNGEN*)
More LessAbstractThe arrays of multiple geophones used in underground seismic prospecting must satisfy two conditions:
1) In each group only a few geophones can be used.
2) The array must work in a rather wide frequency band.
In the present paper the effect of the 3 parameters (geophone spacing, sensitivity and time shift) of a linear array is investigated in order to improve the directional sensitivity of the array.
Necessary conditions which are independent of the frequencies are found for the optimum sensitivities of the geophones in a linear array.
The optimum values of the parameters mentioned above are calculated for arrays of 2 and 3 geophones and for a frequency band width which may be used in underground seismic prospecting.
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MULTIPLE REFLEXIONEN IN NORDWESTDEUTSCHLAND*
More LessAbstractIn N.W. Germany multiple reflections have been observed in numerous areas. They are not curiosities but represent true problems.
In many cases these multiples are recognizable by routine Δt analysis of the records. Sometimes the Δt anomalies are so great that multiples can be recognized without any computational work, merely by looking at the records. This is due to the great contrast between the interval velocities of the Tertiary and of the Upper Cretaceous. One example is discussed fully.
Most of the multiples are of the type AB (a multiple caused by reflections at two different reflectors A and B, and at the surface). It is also shown (by a rough estimate) that this type of multiple is theoretically the most probable. Finally, the interference between the two components of AB (one multiple being reflected first at A, then at B, and the other reflected first at B, then at A), and its appearance in constructed examples, are discussed.
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A TORSION‐MAGNETOMETER FOR MEASURING THE VERTICAL COMPONENT OF THE EARTH'S MAGNETIC FIELD*
By F. HAALCKAbstractThe paper describes a vertical component magnetometer for field work whose magnet system is provided with a torsion axis and in which torsion serves as a standard of measurement. When a measurement is taken the magnetic axis of the system is brought back into the horizontal position by altering the angle of twist (null‐method). The angle of twist is thus a direct measure of the vertical intensity. The instrument is within wide limits independent of the magnetic north‐south direction and may therefore be set up in practically any position. The magnet system is temperature compensated, well damped and provided with an automatic clamping device. With a scale value of 25 gammas per scale division the range of the instrument for direct measurements is 65000 gammas. A tripod of special design enables a measurement to be taken in about one minute. The weight of the torsion magnetometer inclusive of tripod is only 2.9 kg (6.4 lb).
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BOOK REVIEW
Book review in this article
Harold M. Mooney and W. W. Wetzel: “The Potentials about a Point Electrode and Apparent Resistivity Curves for a Two‐, Three‐ and Four‐Layer Earth”, The University of Minnesota Press, Minneapolis. Price $ 18.–.
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Volumes & issues
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Volume 72 (2023 - 2024)
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Volume 63 (2015)
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Volume 62 (2014)
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Volume 61 (2013)
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Volume 60 (2012)
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Volume 59 (2011)
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Volume 58 (2010)
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Volume 57 (2009)
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Volume 56 (2008)
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Volume 55 (2007)
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Volume 54 (2006)
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Volume 53 (2005)
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Volume 52 (2004)
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Volume 51 (2003)
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Volume 50 (2002)
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Volume 49 (2001)
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Volume 48 (2000)
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Volume 47 (1999)
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Volume 46 (1998)
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Volume 45 (1997)
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Volume 44 (1996)
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Volume 43 (1995)
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Volume 42 (1994)
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Volume 41 (1993)
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Volume 40 (1992)
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Volume 39 (1991)
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Volume 38 (1990)
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Volume 37 (1989)
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Volume 36 (1988)
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Volume 35 (1987)
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Volume 34 (1986)
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Volume 33 (1985)
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Volume 32 (1984)
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Volume 31 (1983)
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Volume 30 (1982)
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Volume 29 (1981)
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Volume 28 (1980)
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Volume 27 (1979)
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Volume 26 (1978)
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Volume 25 (1977)
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Volume 24 (1976)
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Volume 23 (1975)
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Volume 22 (1974)
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Volume 21 (1973)
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Volume 20 (1972)
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Volume 19 (1971)
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Volume 18 (1970)
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Volume 17 (1969)
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Volume 16 (1968)
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Volume 15 (1967)
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Volume 14 (1966)
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Volume 13 (1965)
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Volume 12 (1964)
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Volume 11 (1963)
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Volume 10 (1962)
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Volume 9 (1961)
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Volume 8 (1960)
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Volume 7 (1959)
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Volume 6 (1958)
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Volume 5 (1957)
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Volume 4 (1956)
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Volume 3 (1955)
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Volume 2 (1954)
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Volume 1 (1953)