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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 68 (1967), S. 49-65 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary This paper is concerned with the behavior of surface features of the earth which are, or have been, acted on by a stress field. The theory used in this paper is that of classical elasticity. Mathematical models are made which represent perfectly elastic two-dimensional regions which have a notch (or protrusion as a reversed notch can be considered to be). The regions are assumed to be semi-infinite and the notch on the free surface. The loads, or boundary conditions, are then prescribed. The problem of determining the distribution of stress is then considered. Solutions to this problem are presented for the cases of a circular notch, a generalized circular notch and a type of notch whose mathematical representation is given parametrically. Using these solutions and applying a criterion for failure, it is possible to predict what the general trend of the faulting should be in an actual body which the model may represent. Possible applications to geological structures are indicated.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 41 (1958), S. 101-106 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The thesis is advanced that hoodoos (mushroom-shaped erosional features in badlands) are caused by water from cloudbursts turning the corner at the brim of the overhang, flowing for a distance upside-down on the underside. This type of upside-down flow is well known as «teapot effect» in the case of tea being poured from a pot flowing down the underside of the spout rather than straight on into the cup. The measured overhang of hoodoos is in good agreement with the theoretical values obtained from hydrodynamic stability considerations.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 47 (1960), S. 41-54 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The problem of penetration of a fluid into a porous medium containing a more viscous liquid is investigated. It is known that the displacement front may become unstable in this case as it may break up into «fingers». The problem of inception of fingers has been treated previously in the literature by describing the displacement front in terms of its Fourier transform. In the present paper, we generalize earlier procedures by making allowance for an arbitrary elemental growth law. Furthermore, we assume that the phenomenon of fingering is not solely governed by the prevailing flow potentials, but also by the spectrum of heterogeneities in the porous medium. This is achieved by introducing a constant characteristic of the frequency of the heterogeneities in the porous medium. It then turns out that the maximum rate of growth as a function of wave length is considerably shifted from that predicted in the literature. At the same time it is also shown that the difficulty encountered by other workers which consists of small wave lengths growing at an infinitely high rate, is being avoided.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 39 (1958), S. 13-25 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Fault plane solutions of earthquakes which are based onP observations only have the drawback that they yield two orthogonal planes either of which could be the fault plane. In this paper it is investigated what minimal information fromS waves is required to resolve the ambiguity as to which of the two orthogonal planes is the fault plane. It is shown that, in principle, only the sign of the initial impulse of theSH phase at one favorably located station is necesary for this purpose. It is emphasized, however, that the station must be favorably located, i.e. it must be located in certain sectors of the globe. The conditions for the latter are stated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 46 (1960), S. 66-76 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Theories of hydraulic fracturing of wells are usually based upon a model of a well in which the latter is assumed to be equivalent to an infinitely long cylinder. In this fashion, the stress state induced by the pressure in the well turns out to be two-dimensional. This is certainly an oversimplification, and therefore a different model is proposed in the present paper. In this, we assume that the pressure in the well is equivalent to a spherical pressure center. The fracture condition is formulated and the model is applied to the calculation of underground stresses from well data.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 73 (1969), S. 134-142 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Riassunto Il sistema di fracture nella zona di Larderello in Italia è analizzato con l'aiuto della teoria interpretativa detta «isallo stress theory». Alcuni concetti di carattere generale vengono discussi, e le locali caratteristiche geologiche sono brevemente descritte. La direzione di massima compressione orizzontale (PHS) è scelta sulla base di considerazioni sulla tettonica della zona. I risultati cui si perviene sono in soddisfacente accordo con quelli postulati in base ad osservazioni di carattere puramente geologico, e permettono di avanzare una spiegazione unitaria dell'origine delle fratture.
    Notes: Summary An isallo stress analysis of the fracture field in the area of Larderello, Italy, is carried out. Some of the general implications of the theory are discussed, and the local geological features of the area are briefly outlined. ThePHS direction is chosen on the basis of additional structural information. The inferred results are in satisfactory agreement with those expected from field geology, and a tentative attempt to a unitary explanation of the origin of the fracture field is made upon this basis.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 75 (1969), S. 102-116 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary This paper is a further one in the series presenting applications of isallo stress analysis to the investigations of the tectonic stresses in various areas of the world. Specific areas in Tanzania (near the East African Rift Valley), in Texas and in Alaska are investigated and a discussion of the tectonic stresses prevalent therein is given.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 83 (1970), S. 74-81 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The paper reviews the models which have been advocated in the literature for the description of flow through porous media. Special emphasis is placed on statistical models which aim at a theoretical explanation of the occurrence of dispersive effects. These models are a random walk model and new random-topology models.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 52 (1962), S. 69-82 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The theory of the formation of marine terraces is studied. A model is set up which is believed to describe the physical processes involved. This model leads to a nonlinear partial differential equation which is integrated for some special cases by means of a digital computer. Asymptotic solutions of the differential equation are also found by direct analytical means. It is found that no terraces can develop if eustatic changes occur at a constant rate, contrary to some contentions that have been advanced in the literature.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 89 (1971), S. 32-44 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary This paper discusses a class of stochastic models of flow through porous media in which the randomness is attached to the structure of the medium rather than to the flow path. These models are obtained by generalizing an earlier model available in the literature where a regular ‘crystal’ was taken in which bonds (flow channels) were dammed in a random fashion, yielding a ‘random maze’. The hydraulic properties of general models of this type are calculated; in particular, it is shown that they exhibit the phenomenon of dispersion whereby the factor of dispersion turns out to be a linear function of the percolation velocity.
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