- Home
- A-Z Publications
- Geophysical Prospecting
- Previous Issues
- Volume 8, Issue 4, 1960
Geophysical Prospecting - Volume 8, Issue 4, 1960
Volume 8, Issue 4, 1960
-
-
A SHOCK WAVE THEORY FOR THE GENERATION OF THE SEISMIC SIGNAL AROUND A SPHERICAL SHOT HOLE
By W. E. PEETAbstractThe shape of the seismic signal generated by an explosive charge is assumed to be governed by shock‐wave phenomena in a non‐linear region around the shot hole.
The dimensions of this shock‐wave region are shown to depend on the weight of the explosive charge and the properties of the medium in which the shot is fired.
The presented theory enables us to elucidate the power law relationship between the amplitude of the seismic pulse and the weight of the charge fired, in the literature often denoted by A = c.Qn, in which A is the pulse amplitude, Q the charge weight and c a constant.
Experiments have been made to check the theory and the results are promising.
-
-
-
DIRECTION SHOOTING*
Authors R. BORTFELD, H. HÜRTGEN and H. KOPPELAbstractBy direction shooting is understood a method of continuous seismic profiling with shots distributed along the total length of the geophone spread, the shots being fired either with time delays in the field, or, recorded singly on magnetizable material and composited with time‐delays. Therewith, the subsurface can be probed in any desired direction, enhancing reflections from these directions and attenuating or eliminating events from all other directions. For each reflection, the correct delay can be found by a simple procedure from a single trial record.
A complete description of the method is given, inclusive of all procedures and proofs pertaining to it. Synthetic examples and field examples illustrate the efficiency of the method and its resolving power.
-
-
-
DIRECTIONAL SCANNING WHEN PLAYING‐BACK SEISMIC MAGNETIC RECORDS*
More LessAbstractIn this paper we describe and give examples of procedures of magnetic playback which make it possible to emphasize particular reflections with respect to other reflections of differing step‐out. The procedure consists of 100% mixing between non‐adjacent channels, using either direct or, more frequently, reversed‐polarity mixing signals. This procedure allows the effective separation of differently inclined reflections.
-
-
-
THE INFLUENCE OF SURFACE FORMATIONS ON THE APPARENT RESISTIVITY VALUES IN ELECTRICAL PROSPECTING*)
By L. ALFANOAbstractIn this first part, 1) we have examined the disturbances on resistivity measurements caused by some simple examples of surface irregularities with a cylindrical structure. The study has been carried out applying a theory developed in a previous paper (Alfano 1959)
In the first place, we have considered the case of measurements carried out with the potential electrodes near the surface irregularities, and the current electrodes more distant from those irregularities. This case is related to those methods of prospecting in which it is preferred to keep the current electrodes fixed and to move the potential electrodes.
One method has been pointed out which will separate, in the measured data, the component of the field due to deep formations, from the components due to surface irregularities. Afterwards, we have considered the case with current electrodes near the dishomo‐geneities and potential electrodes more distant from them. For both cases, numerical examples are shown, both for secondary charge values and for apparent resistivity values.
Finally, asymptotic values of vertical electrical soundings have been calculated for some cases, rigorously showing that they, in the presence of surface disturbances, are not equal, generally, to the true resistivity of a possible infinite substratum.
It follows that the measurement of resistivity of an infinite substratum, by means of the resistivity asymptotic value of only one sounding, is not possible.
The numerical results given have been obtained by means of calculations based on the abovesaid paper, but whose operative details shall be described in the second part of this paper.
The second part also will deal with the cases of surface dishomogeneity with a non‐cylindrical structure.
-
-
-
SOME FORMULAE FOR INTERPRETING LOCAL GRAVITY ANOMALIES
By R. A. SMITHAbstractLet Oxyz be a system of rectangular axes with origin at the earth's surface and with the z axis pointing vertically downwards. If a body B lies wholly] between the planes z=h, z=I then for all x, y and for n= 1, 2, 3 it is proved that
where a=h/d, β=l/d and K is the gravitational constant. Dn are very easily computed from the Bouger anomaly and Jn are tabulated in this paper.
-
-
-
BOOK REVIEWS
Book Reviewed in this article:
Louis de Vries, Technical and Engineering Dictionary.
Mrs S. Duclaux, Seismétrie théorique.
-
Volumes & issues
-
Volume 72 (2023 - 2024)
-
Volume 71 (2022 - 2023)
-
Volume 70 (2021 - 2022)
-
Volume 69 (2021)
-
Volume 68 (2020)
-
Volume 67 (2019)
-
Volume 66 (2018)
-
Volume 65 (2017)
-
Volume 64 (2015 - 2016)
-
Volume 63 (2015)
-
Volume 62 (2014)
-
Volume 61 (2013)
-
Volume 60 (2012)
-
Volume 59 (2011)
-
Volume 58 (2010)
-
Volume 57 (2009)
-
Volume 56 (2008)
-
Volume 55 (2007)
-
Volume 54 (2006)
-
Volume 18 (1970 - 2006)
-
Volume 53 (2005)
-
Volume 52 (2004)
-
Volume 51 (2003)
-
Volume 50 (2002)
-
Volume 49 (2001)
-
Volume 48 (2000)
-
Volume 47 (1999)
-
Volume 46 (1998)
-
Volume 45 (1997)
-
Volume 44 (1996)
-
Volume 43 (1995)
-
Volume 42 (1994)
-
Volume 41 (1993)
-
Volume 40 (1992)
-
Volume 39 (1991)
-
Volume 38 (1990)
-
Volume 37 (1989)
-
Volume 36 (1988)
-
Volume 35 (1987)
-
Volume 34 (1986)
-
Volume 33 (1985)
-
Volume 32 (1984)
-
Volume 31 (1983)
-
Volume 30 (1982)
-
Volume 29 (1981)
-
Volume 28 (1980)
-
Volume 27 (1979)
-
Volume 26 (1978)
-
Volume 25 (1977)
-
Volume 24 (1976)
-
Volume 23 (1975)
-
Volume 22 (1974)
-
Volume 21 (1973)
-
Volume 20 (1972)
-
Volume 19 (1971)
-
Volume 17 (1969)
-
Volume 16 (1968)
-
Volume 15 (1967)
-
Volume 14 (1966)
-
Volume 13 (1965)
-
Volume 12 (1964)
-
Volume 11 (1963)
-
Volume 10 (1962)
-
Volume 9 (1961)
-
Volume 8 (1960)
-
Volume 7 (1959)
-
Volume 6 (1958)
-
Volume 5 (1957)
-
Volume 4 (1956)
-
Volume 3 (1955)
-
Volume 2 (1954)
-
Volume 1 (1953)