bluuebunny/crossref_metadata_2025_split huggingface dataset:
LABORATORY DETERMINATIONS OF ELASTIC PROPERTIES OF SOME LIMESTONES
Authors: KUIPER J. , VAN RYEN W. M. L. , KOEFOED O. 
Published: April 2006

AbstractUsing a resonance method, determinations have been made of the longitudinal bar velocity and of Poisson's ratio of thirteen different chemically pure limestones. The relation between the velocity and the density showed far less scatter than in the determinations previously published; this is primarily attributed to the high purity of the specimens used. The measurements further showed a tendency of the values of Poisson's ratio to increase with increasing density.
TIME VARIATIONS OF THE CALIBRATION OF THE WORDEN GRAVITY‐METER*
Authors: INGHILLERI G. 
Published: April 2006

AbstractPrecision calibration tests carried out with a Worden gravimeter in environment conditions as varied as possible have led to the following conclusions. The secular variation curve of the calibration shows that the secular relative variation has been very appreciable in the first year of life of the instrument, precisely of 1.3 × 10−3 in 13 months, while it has been practically zero in the second year. This must be ascribed to the fact that at the beginning of the operations the gravity‐meter had just arrived from the factory with its measuring body renewed.On the other side the effect of 24°C of temperature difference between two series of determinations reveals itself in a variation of 0.0022 of the value of the calibration, so that it can be established that the variation of the calibration is I‰ for each 10°C of temperature variation.
APPLICATION OF THE CONTINUOUS VELOCITY LOG TO ANISOTROPY MEASUREMENTS IN NORTHERN SAHARA; RESULTS AND CONSEQUENCES
Authors: DE SEGONZAC PH. DUNOYER , LAHERRERE J. 
Published: April 2006

AbstractAnisotropy measurements were carried out in two wells 300 km apart in the Northern Sahara, in order to improve the interpretation of seismic refraction surveys.These measurements were based on; the shortening of experimental oblique travel‐times with respect to theoretical, travel‐times computed by disregarding anisotropy. A perfect knowledge of the velocity distribution is required in order to eliminate all influence of refraction; therefore a continuous velocity log is indispensable.The results in the two wells are in agreement, and show that anisotropy is essentially a function of lithology. The following values were obtained:
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Consequences pertaining to seismic refraction are as follows:— Depths computed without anisotropy are too small by 8 % to 9 %, i.e. about 300 meters.— The error on offsets reaches 70 %.— Depth computations carried out by assigning anisotropy factors at the sight of lithology gave very satisfactory results.— High velocity, highly anisotropic formations such as anhydrite play a very important part in the propagation of refracted waves and in interpretation.Consequences pertaining to seismic reflection are as follows:— Velocity profiles yield velocities closer to horizontal velocities than to vertical velocities.— Depth and migration computations are significantly influenced by high velocity, highly anisotropic formations such as anhydrite.
WELL VELOCITY DETERMINATIONS IN THE ENGLISH TRIAS, PERMIAN AND CARBONIFEROUS
Authors: WYROBEK S. M. 
Published: April 2006

AbstractTo obtain inferences useful in predicting the overburden velocities, a statistical study of velocity data was undertaken on 46 well velocity surveys confined mainly to Eastern England. Five formations were particularly studied: Keuper, Bunter, Permian, Coal Measures and Millstone Grit. Their interval velocities plotted against the mean depth of the interval below the surface supplied five equations of the form V=k. H1/n, which cover the range of depth explored down to 7000 ft. Comparison of these results shows that the interval velocities increase with depth and in the Keuper and Permian attain a maximum value nearly twice that in the remaining three formations. The interval velocities of these formations are confined within a relatively narrow band of 9000–12000 ft/sec. and the formations cannot be distinguished satisfactorily by their interval velocities alone. More practical results were obtained considering the relation between the vertical time and depth to the top of the Permian, Coal Measures, Millstone Grit and Carboniferous Limestone. For each of these a linear relation T=k. H+ To, was obtained from which the vertical time T can be predicted from the known depth with a probable error of ± 4 millisecs.
RESULTS OF UNDERGROUND‐SEISMIC REFLECTION INVESTIGATIONS IN THE SIDERITE DISTRICT OF THE SIEGERLAND*
Authors: SCHMIDT G. 
Published: April 2006

AbstractThe iron ores of the Siegerland district are found in lodes occurring in schists of Lower Devonian age. These lodes, normally dipping almost perpendicularly, could be traced only by seismic reflection measurements underground, up to distances of approximately 500 m. The geophones were attached to the walls of the galleries. The frequencies of the recorded longitudinal and transverse waves ranged from 200 to 500 c.p.s. By this method a new siderite lode was discovered.
A EUROPEAN FIELD OF THE NORMAL GEOMAGNETIC VERTICAL INTENSITY AND ITS SECULAR VARIATION
Authors: BOCK R. 
Published: April 2006

SummaryA uniform field of the normal geomagnetic vertical intensity and its normal dependence on the first and second powers of latitude and longitude are derived for Europe and represented by sketches. The epochs of 1938.5, 1941.5, 1944.5, 1947.5, 1950.5, 1953.5, and 1956.5 have been chosen.It is suggested that anomalies of the vertical intensity should be given according to this field in order to obtain, in course of time, a coherent image of the magnetic effects of the European continent.
A GENERALIZED CAGNIARD GRAPH FOR THE INTERPRETATION OF GEOELECTRICAL SOUNDING DATA
Authors: KOEFOED O. 
Published: April 2006

AbstractThe Cagniard method of interpreting geoelectrical sounding data is based on the use of an empirical graph which expresses the relation between the resistivity and thickness of the second subsurface layer on one side, and on the other side the replacement resistivity and replacement thickness which are derived from the two‐layer sounding curve which is asymptotic to the second branch of the observed sounding curve. In his method separate graphs of this type are required for different values of the resistivity of the third subsurface layer. In the present paper a generalized Cagniard graph is derived which has the advantage of being independent of the value of the resistivity of the third subsurface layer. Finally, the accuracy of the method is discussed, and a procedure is described for extending its use to cases where more than three subsurface layers intervene.
A SHOCK WAVE THEORY FOR THE GENERATION OF THE SEISMIC SIGNAL AROUND A SPHERICAL SHOT HOLE
Authors: PEET W. E. 
Published: April 2006

AbstractThe 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.
SOME FORMULAE FOR INTERPRETING LOCAL GRAVITY ANOMALIES
Authors: SMITH R. A. 
Published: April 2006

AbstractLet 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
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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.
CALCUL DE L'ATTRACTION D'UN POLYGONE HORIZONTAL DE DENSITÉ UNIFORME*
Authors: GOGUEL JEAN 
Published: April 2006

AbstractThe vertical component of the attraction exerted by a horizontal homogeneous polygon is obtained as the sum of terms proportional to the difference, for each of the vertices, between the external angle and its spherical perspective. A set of computation charts is presented, each for a fixed value of the angle of the polygon (22° 30′, 30°, 45°, 67° 30’ and 90°). These charts give the difference between the external angle and its spherical perspective as a function of the quotient of the distance from the sides to the vertical through the station over the depth. The chart for the right angle is an alignment chart, permitting a more accurate reading; the others are graphs in rectangular coördinates.For a remote station the result would be obtained as a small difference between relatively large quantities, and consequently with a not quite satisfactory precision. For these stations it is preferable to assume the entire mass to be concentrated in the centre of gravity.
THE ELECTROMAGNETIC RESPONSE OF A MAGNETIC IRON ORE DEPOSIT
Authors: WARD STANLEY H. 
Published: April 2006

AbstractField experiments in the vicinity of a tabular body of nearly massive magnetite have demonstrated that the body may respond in either of two ways; it may react as a permeable mass, or it may react as an eddy current inductor, depending upon the frequency employed. If several frequencies, spanning a broad range, are employed, both types of response will be experienced. The transition from one type of response to the other would appear to have considerable significance. Based upon theoretical and empirical work to date, it seems possible to establish a relationship between transition frequency and percentage magnetite at any given section of a deposit.
ENERGIE DES VIBRATIONS ET FILTRAGE NON LINEAIRE*
Authors: BARANOV V. 
Published: April 2006

AbstractA filtered seismic trace often appears as an almost sinusoidal curve. The reflected energy arrivals are superimposed and interfere with the continuous oscillations of the trace, and are therefore often difficult to distinguish. This is the chief difficulty in picking reflections. The situation is similar to that met with in gravimetry when a strong regional anomaly conceals small local anomalies. However, a regional anomaly is regular and broad, and owing to these two characteristics it can be removed. In reflection seismology batches of energy may also be concealed by oscillations of a continuous character. The main difference lies in the fact that the background of continuous seismic vibrations is not static, as is the case in gravimetry, but variable with time. However, a fairly constant physical quantity corresponds to these vibrations, which are composed partly of noise, partly of undesired secondary reflections. This quantity is the energy of motion of the surface layer of the ground. It is this troublesome energy that we intend to remove, in order to keep only the useful, actually reflected, energy.These remarks clearly demonstrate the importance of an investigation of the energy contained in the surface layer of the ground. After showing that, in the simplest case, the density of this energy can be expressed almost exactly by the formula u
′2−uu′′in which u′ is the velocity of a ground particle, we show how the non‐linear filtering defined by this formula can be realized, and we provide a few examples.
SEISMIC WAVES IN A MATHEMATICAL MODEL OF THE SURFACE LAYER*
Authors: BORTFELD REINHARD 
Published: April 2006

AbstractThe surface layer is replaced by a layer in which the velocity changes linearly with the depth, i.e. by a transition layer. A plane irrotational wave of arbitrary shape travels vertically upward and hits this layer. The multiples produced by differential reflections in the layer and by reflections at the free boundary are computed. From the third order on, these multiples look exactly like empirical reflections. The sum of all multiples is the solution of the differential equations of the problem, and has some formal mathematical similarity to diffraction phenomena known from optics.
THE RELATIVE CONTRIBUTIONS OF REMANENT AND INDUCED MAGNETISM TO THE OBSERVED MAGNETIC FIELD IN NORTHEASTERN ALBERTA
Authors: WATKINS N. D. 
Published: April 2006

AbstractThe ratios of induced to remanent magnetic intensities have been determined for samples of Precambrian rock from part of the Canadian Shield in northeastern Alberta.The relatively insignificant contribution of remanent magnetism to the observed field indicates that interpretation techniques based on the assumption of zero remanent intensity can be used.Other implications of the magnetic measurements are discussed briefly.
THE GENERATION OF SEISMIC WAVES BY EXPLOSIONS*
Authors: LINSSER HELMUT 
Published: April 2006

AbstractIn the mathematical treatment of the propagation of seismic waves the process in the medium surrounding the point of explosion is introduced as initial condition into the differential equation. It is the purpose of this paper to contribute to the knowledge of this process.The treatment of the process of explosion is a difficult one because the elastic limit is exceeded in the surroundings of the point of explosion. To gain a better view on the acting forces the space concerned is replaced by a simplifying model. It is shown that a permanent deformation is caused by the explosion. This deformation will be especially intensive if the rock does not offer any resistance to tensile forces.To determine the extent of such a permanent deformation a sudden release of pressure — the opposite of an explosion — was recorded by seismographs. It has been proved that any seismic waves of measurable magnitude are not produced. This leads to the conclusion that permanent deformation plays an essential part in the generation of seismic waves.
EXEMPLES D'APPLICATION DE LA REPRESENTATION CONFORME A L'INTERPRETATION DU CHAMP TELLURIQUE*
Authors: KUNETZ G. , DE GÉRY J. CHASTENET 
Published: April 2006

AbstractThe method of conformal transformation is applied to determine the distribution of telluric current density at the surface for several subsurface situations. To this end one starts of from a configuration of boundaries between media of different resistivities and of two equal and opposite current poles, for which the potential distribution can be easily determined. Then a suitable conformal transformation is applied, by which the two current poles are displaced to infinity, and the boundary between the media are made to correspond to typical layer configurations in the subsurface. Several examples of the method are discussed in detail, leading to typical subsurface structures as well as to typical topographic conditions.
MESURES D'AMPLITUDE DANS LES SONDAGES: LE LOG D'ATTENUATION *
Authors: MORLET J. , SCHWAETZER T. 
Published: April 2006

ResumeParmi les différents facteurs agissant sur l'amplitude des signaux acoustiques enregistrés au cours des mesures continues de vitesse dans les puits, le coefficient d'atténuation semble présenter beaucoup d'intérêt pour la détermination des qualités mécaniques des roches, en particulier la continuité de la matrice, donc dans une certaine mesure la perméabilité.Afin d'éliminer les facteurs secondaires agissant sur l'amplitude, nous avons été amenés à enregistrer le rapport des amplitudes aux deux récepteurs de la sonde C.V.L. Nous avons donc étudié un appareil permettant d'enregistrer les amplitudes des premières arrivées aux deux récepteurs, ainsi que le rapport de ces amplitudes.Nous présentons ici les premiers résultats obtenus par la mesure continue de l'atténuation des ondes acoustiques dans différents types de formations. Des comparaisons sont faites avec les diagraphics de vitesse, de résistivité et de radioactivité.Le log d'atténuation semble permettre la détermination de la lithologie et plus particulièrement la localisation des zones fracturées et perméables. Bien que nous n'ayons que peu d'expérience de ce nouveau type de diagraphie, il nous semble que les premiers résultats obtenus soient très prometteurs.
THE HYPERBOLIC INCREASE OF DEPTH WITH TIME
Authors: KUNZ BRUNO 
Published: April 2006

AbstractThe geometric description of wave fronts and ray paths has previously always started from the velocity distribution which has been chosen as simple as possible in order to be able to solve the integrals occurring in the basic equations. As the velocity is derived from the measured values of path and time, it is preferable to start from the path‐time function. There are exponential, parabolic and hyperbolic path‐time functions; the first and the second case correspond to the known linear and parabolic velocity functions. The hyperbolic case, on the other hand, has not yet been covered in literature. In the first two cases, two parameters–a and vo–can be chosen arbitrarily. In the hyperbolic case, we have 3 parameters (a, b and v)o at our disposal; this makes for a better approximation to actual conditions. A special advantage is seen also in the fact that the velocity does not become infinite with increasing depth but approaches a finite limit.
IN PURSUIT OF THE ERRANT SEISMIC PULSE*
Authors: HAGEDOORN J. G. 
Published: April 2006

AbstractThe results obtained from a series of geophones extending vertically from the surface down to a particularly strong reflector 450 m deep have provided an insight into the properties of the various types of wave generated by an explosion in the ground and have shown how these waves are converted into other types near the surface and at a reflector. The direct shear pulse generated by an explosion was observed to be quite simple and to penetrate to the deepest geophone even from large horizontal distances, but to be much more attenuated and broadened on its way through the earth than the compressional pulse. This shear pulse was found to be the cause of the ground‐roll commonly observed at the surface. A clear PS reflection, of the same magnitude as the PP reflection, was observed from the reflector 450 m deep. This shear event starts out from the reflector as a short and simple pulse, but does not persist as such on its way to the surface. It loses its sharpness well before reaching the base of the weathered layer, whereas the reflected compressional pulse is hardly affected at all.
HIGH SPEED CALCULATION OF GRAVITY AND MAGNETIC PROFILES ACROSS TWO‐DIMENSIONAL BODIES HAVING AN ARBITRARY CROSS‐SECTION*
Authors: MORGAN N. A. , GRANT F. S. 
Published: April 2006

AbstractA method is found for programming the calculation of gravity and magnetic profiles across two‐dimensional bodies of arbitrary cross‐section for high‐speed computers. It is based upon an idea applied recently by Worzel, Landisman and Talwani, of approximating the cross‐section with an n‐sided polygon. The gravity and magnetic formulae are functions of the coordinates of the vertices. A profile of each kind takes only a few seconds to compute, and the accuracy appears to be at least as good as that of graticules.
APERçUS STATISTIQUES SUR L'INTERPRETATION EN AEROMAGNETISME*
Authors: CHEREAU J. Y. 
Published: April 2006

AbstractWhen inspecting maps that were obtained a few years ago as a result of the interpretation of aeromagnetic surveys, one is divided between feelings of satisfaction about well confirmed predictions, of regret about unfortunate choices or errors that could have been avoided by present experience and of confusion in regard to certain still poorly understood phenomena.Some documents of the Bureau de Recherches de Pétrole have been examined in order to evaluate the precision of aeromagnetic interpretations and to find possible sources of the observed discrepancies.
LA SURFACE D'ONDE DANS UN MILIEU ELASTIQUE ANISTROPE*
Authors: LOEB J. 
Published: April 2006

AbstractThe present work was initiated by an account given by Messrs. Kunetz and ?Erceville. It is greatly inspired by the article of G. W. Postma: Wave propagation in a stratified medium. There a construction of the “wave front” is given, starting from the surface of the velocities. This latter surface is the pedal of the wavefront. This theory is based on a certain section of Love's Treatise on the Mathematical Theory of Elasticity (Ch. XIII, sect. 209). However, no proof of this theory has been provided, neither in Postma's article nor in Love's work.It is the intention of this article to supply such a proof. Also the construction is proved to be valid only for distances from the point source which are large compared with the wavelength.
SOME THEORETICAL ASPECTS OF ELECTRODE POLARIZATION IN ROCKS*
Authors: BHATTACHARYYA B. K. , MORRISON H. F. 
Published: April 2006

AbstractA study has been made on the influence of the several variables of an electrode‐electrolyte system on the different parameters usually measured in connection with the induced polarization method of geophysical exploration. Both the reaction resistance and the Warburg impedance of the system are found to vary appreciably with active ion concentration. The activation energy barrier exerts a predominant influence only on the former, whereas the salt concentration is important to a small degree in the determination of only the latter.With a simple equivalent electrical circuit to represent the complex mechanism of conduction of electrical currents through mineralized rocks, the amplitude and phase of the metal factor are evaluated at a frequency of 10 cps. An analysis is then made to determine the build‐up and decay characteristics of the transient signal in the rock induced by a rectangular current pulse. All these measurable quantities are highly dependent on the salt and active ion concentrations. It is interesting to note that the build‐up or decay time of the transient signal increases normally as the square of the solution resistance and inversely as the square of the Warburg impedance. The activation energy barrier exerts, practically no influence on the metal factor nor on the transient signal.
CALCUL DE LA FORME ?UNE STRUCTURE HOMOGENE A PARTIR DE SON CHAMP GRAVIMETRIQUE*
Authors: LA PORTE M. 
Published: April 2006

AbstractA given gravity field is considered; it is assumed to be due to a homogeneous structure.The method of computation presented here makes it possible to determine one of the limits of such a structure (upper or lower), provided the other limit and the density contrast of the structure are known.Among the various applications of this method, location of the upper limit of buried palaeo‐reliefs can be mentioned.The calculation is designed for electronic computers, and uses one of the properties of the downward continuation of the gravity field. The process is iterative and takes place at the corners of a regular grid.Modern computers can handle several thousand points at a time.
TWO METHODS APPLICABLE TO COMPUTERS FOR EVALUATING MAGNETIC ANOMALIES DUE TO FINITE THREE DIMENSIONAL BODIES*
Authors: BOTT M. H. P. 
Published: April 2006

AbstractTwo methods applicable to computers are described which are designed to evaluate the vertical, horizontal and total intensity magnetic anomalies due to finite three‐dimensional bodies of uniform polarisation contrast. The direction of polarisation need not be co‐linear with the Earth's field, thus allowing for a remanent component; and the calculation may be performed for a given model for several different directions of polarisation concurrently. The first programme depends on the transformation from a volume integral to a surface integral and the approximate representation of the surface by a series of plane polygonal faces. The second programme is based on an extension of Vacquier's graphical method.