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  • 1
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    In:  Pageoph, Leipzig, 3-4, vol. 112, no. 4, pp. 701-725, pp. L19606, (ISBN: 0-12-018847-3)
    Publication Date: 1974
    Keywords: Rock mechanics ; Earthquake precursor: prediction research ; Earthquake precursor: simulated in laboratory tests ; cracks and fractures (.NE. fracturing) ; Dual Induction Latero logAT
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  • 2
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    In:  Pageoph, Leipzig, 3-4, vol. 113, no. 4, pp. 149-167, pp. L19606, (ISBN: 0-12-018847-3)
    Publication Date: 1975
    Keywords: Rock mechanics ; Earthquake precursor: prediction research ; Earthquake precursor: simulated in laboratory tests ; cracks and fractures (.NE. fracturing) ; Dual Induction Latero logAT
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  • 3
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    In:  Pageoph, Leipzig, 3-4, vol. 114, no. 4, pp. 1031-1082, pp. L19606, (ISBN: 0-12-018847-3)
    Publication Date: 1976
    Keywords: Rock mechanics ; Earthquake precursor: prediction research ; Earthquake precursor: simulated in laboratory tests ; cracks and fractures (.NE. fracturing) ; Dual Induction Latero logAT
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  • 4
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    In:  Pageoph, Leipzig, 3-4, vol. 114, no. 4, pp. 119-139, pp. L19606, (ISBN: 0-12-018847-3)
    Publication Date: 1976
    Keywords: Rock mechanics ; Earthquake precursor: prediction research ; Earthquake precursor: simulated in laboratory tests ; cracks and fractures (.NE. fracturing) ; Dual Induction Latero logAT
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  • 5
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    In:  Pageoph, Leipzig, 3-4, vol. 115, no. 4, pp. 357-374, pp. L19606, (ISBN: 0-12-018847-3)
    Publication Date: 1977
    Keywords: Earthquake precursor: prediction research ; Induced seismicity ; Rock bursts (see also ERDSTOSS and GEBIRGSSCHLAG) ; Earthquake precursor: statistical anal. of seismicity
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 112 (1974), S. 701-725 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary A scale independent failure theory governing the initiation and subsequent growth of the shear fault in rock is presented in this article. Four distinct phases of behavior in this theory are shown to precede fault growth in rock. 1)Dilatant Phase: Cracks form in the rock in response to the applied stresses. This phase begins at a maximum principal stress whose magnitude is usually well below the ultimate strength of the rock. 2)Inclusion Phase: Clusters of cracks develop in the rock at a point in time when the rock is within a few per cent of its ultimate strength. The clusters behave physically as low modulus elastic inclusions embedded within a host material of higher modulus. As a result of this ‘elastic’ contrast, there is a rotation of the principal stress axes and a decrease in the magnitude of the principal stress difference in the focal region of the inclusion; that is, the region into which the inclusion will grow at failure. 3)Closure Phase: In this phase, there is closure of cracks in the focal region in response to the decrease in the magnitude of the principal stress difference due to the formation of the inclusion. As a result of crack closure in the focal region, the stress concentration in the focal region increases and becomes a maximum once all cracks which opened during the dilatant phase are closed. At this time, the transverse tensile stress in the interior of the inclusion also reaches a maximum. Macrocrack growth within the inclusion begins. 4)Growth Phase: Fault growth commences during this phase. Reopening of previously closed cracks occurs due to the increase in the principal stress difference in the focal region resulting from macrocrack growth within the inclusion. New cracks form and rapid growth of the macrocrack (in its own plane) occurs once the length of the mecrocrack exceeds a critical value. The fault represents the portion of the macrocrack which has closed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 114 (1976), S. 119-139 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A theory of deep earthquakes, termed the inclusion collapse theory, is proposed in this paper. In the inclusion theory of crustal (or shallow) earthquakes, faults were shown to terminate within an inclusion zone. This zone represents a region within the brittle portion of the lithospheric plate that contains open cracks (voids) of varying sizes that, to a first order approximation, are uniformly distributed throughout the inclusion zone. When the lithospheric plate containing these faults and their associated inclusions is subducted into the mantle, the stress normal to the fault planes must increase. A depth is eventually reached where slippage along the fault planes is no longer possible. Earthquakes are postulated to occur at a specified depth within the mantle as a result of processes leading to collapse of these voids. When the long-term modulus of the plate is much greater than the long-term modulus of the mantle, large pressures are shown to develop within the plate during periods of active subduction. These pressures are shown to be sufficient to initiate partial collapse of voids of similar geometry throughout the inclusion zone. The inclusion collapse theory and the concentration of pressure within the plate lead to four results. (1) Earthquakes that are produced by a void collapse mechanism will not occur below a subduction depth calculated to be between 350 and 1000 km (2) The physical process most likely responsible for producing void collapse is the formation of shear, melt zones whose thicknesses are on the order of 1 to 10 cm in the immediate vicinity of the voids. This mechanism, is shown to produce a ‘precursor’ time on the order of a few hundred seconds during which there is a release of shear strain prior to the earthquake. (3) The maximum energy released by void collapse is independent of the source depth. (4) The number of earthquakes produced by this process will decrease hyperbolically with source depth. Source depth, in the context used in this article, refers to the depth in the mantle to the inclusion zone where voids of similar geometry are undergoing partial collapse. The maximum source depth refers to the depth where all voids have closed.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 114 (1976), S. 727-739 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The scale invariant inclusion theory of failure is applied to the problem of aftershock sequences. In the inclusion theory, a macrocrack, or void of low aspect ratio, the length of which depends upon the magnitude of the impending mainshock, forms within the inclusion zone of the impending earthquake. The fault zone that precedes the inclusion zone represents that part of the macrocrack that has closed. It is shown that bifurcation (branching) of the macrocrack and its associated fault must occur within the focal region of the inclusion during the growth phase of the earthquake. The bifurcation process produces extensive faulting of the material that comprises the focal region. A prediction of the inclusion theory is that each fault within the focal region will terminate within a zone of concentrated dilatancy that may or may not be in an unstable state. When the zone is unstable, an aftershock will occur. It is shown that these inclusion zones will, on the average, occur near the boundaries of the focal region. Failure of these unstable zones leads to additional failures within the interior portions of the focal region. These failures represent ‘lock point’ failures along the fault(s) and will, in general, exhibit few or no additional aftershocks. The bifurcation model of aftershock sequences leads to five results: (1) The aftershock sequence will exhibit an inverse hyperbolic time decay law when the stresses that are applied at distances far removed from the hypocenter remain constant during the sequence and when there isno interaction between the brittle lithosphere (where aftershocks occur) and the underlying asthenosphere. (2) The mean magnitude of any group of aftershocks within the sequence will be approximately constant in time. (3) The aftershocks will, in general, have focal mechanisms identical to that of the mainshock. (4) Large seismic events that occur throughout the aftershock zone will be independent of one another when the aftershocks are sufficiently far apart (∼two-three ‘fault’ lengths) and when the applied tectonic stresses remain constant during the sequence. (5) The bifurcation model predicts that theb-value of the aftershock sequence will be 1.0 when both the Utsu relationship between aftershock area and mainshock magnitude and the Gutenburg Richter frequency-magnitude relationship are satisfied.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 113 (1975), S. 149-168 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The scale independent inclusion theory of rock failure developed in Part I is applied to the problem of crustal earthquakes and, in particular, to the problem of premonitory phenomena reported to precede such earthquakes. Several well-known premonitory effects such as anomalous variation in the ratio of longitudinal (V p ) and shear (V s ) seismic velocities,V p /V s , tilt, regional and local crustal movements and stress axis rotation, to mention a few, are shown to be a natural consequence of the physical processes leading to failure in dry rock. The effects of fluids on failure in the focal region of a potential earthquake are considered in terms of the scale independent inclusion theory.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1434-453X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Description / Table of Contents: Zusammenfassung Experimentelle Bestimmung des wahren Spannungs-Dehnungs-Verhaltens von sprödem Gestein Es wird über Ergebnisse experimenteller Studien über das Verhalten von sechs verschiedenen Gesteinen berichtet, welche unter einachsigem Druck im Nach-Bruch-Bereich deformiert wurden. Aufgrund der Beobachtung, daß eine Gesteinsprobe im Nach-Bruch-Bereich als aus brüchigem und gebrochenem Gestein zusammengesetzt betrachtet werden kann und unter der Annahme, daß die Abminderung der Belastbarkeit des Gesteins im Nach-Bruch-Bereich durch die Verringerung der wirksamen Querschnittsfläche der Probe infolge des Wachsens von großen Rissen in der Gesteinsprobe verursacht ist, wird gezeigt, daß es eine maximale wahre Spannung gibt, welche das ungebrochene, feste Gestein ohne inelastische Deformation ertragen kann. Diese Spannung ist konstant und wird als wahre Bruchfestigkeit des Gesteins angesprochen. Die Größe dieser Spannung errechnet sich durch Division der auf die Gesteinsprobe an irgendeinem Punkt der Nach-Bruch-Kurve ausgeübten Kraft durch die wahre, Belastung tragende Querschnittsfläche der Gesteinsprobe an diesem Punkt. Es wurden theoretische und experimentelle Techniken entworfen, welche eine Schätzung der Verminderung der Belastungsfläche an irgendeiner Stelle längs der Nach-Bruch-Kurve der Probe erlauben. Für Gesteinstypen, welche in diesen Untersuchungen benützt wurden und welche an im Voraus gewählten Stellen längs der Nach-Bruch-Kurve deformiert wurden, gaben unter der Annahme, daß das gebrochene Gestein nichts von der aufgebrachten Belastung trug, die beiden Techniken zur Messung der tatsächlich lasttragenden, wirksamen Fläche gleiche Resultate.
    Abstract: Résumé On présente les résultats d'une étude expérimentale du comportement de six types de roches chargées en compression simple dans leur domaine respectif de déformation après la rupture. Si l'on remarque qu'un échantillon de roche après la rupture peut être considéré comme composé de roche cassée et de roche non cassée, et en supposant que la réduction de résistance dans le domaine après la rupture est due à la réduction de la section droite intacte de l'échantillon, réduction résultant de la croissance de grandes fissures dans l'éprouvette, on montre qu'il existe une contrainte vraie maximale que la roche peut supporter sans déformation permanente. Cette contrainte est constante et est réputée être la résistance vraie à la rupture. La valeur de cette contrainte est calculée en divisant la force sur l'échantillon en chaque point de la courbe effort-déformation après la rupture, par la section droite supportant alors véritablement la charge. Des techniques théorique et expérimentale sont développées, qui permettent d'estimer la surface portante vraie de l'échantillon en tout point de la courbe après la rupture. Pour les types de roches utilisées dans cette étude, qui furent déformées à des états pré-déterminés du domaine après la rupture, et avec l'hypothèse que la roche fracturée ne supportait plus aucune contrainte, les deux méthodes de mesures de la section portante ont donné des résultats équivalents.
    Notes: Summary An Experimental Determination of the True Uniaxial Stress-Strain Behavior of Brittle Rock Results are presented of an experimental study of the behavior of six rock types deformed under uniaxial compression into their respective post-failure regions. Based on the observation that a rock sample in a post-failure state can be considered to be composed of broken and unbroken rock and assuming that the reduction in load-bearing capability of rock in the post-failure region is due to a reduction of the effective cross-sectional area of the specimen resulting from the growth of large cracks within the rock sample, we show that there is a maximum true stress that the unfractured solid rock can sustain without inelastic deformation. This stress is constant and is defined to be the true failure strength of the rock. The value of this stress is calculated by dividing the force on the rock sample at any point along the post-failure curve by the true load-bearing cross-sectional area of the rock sample at that point. Theoretical and experimental techniques are developed which allow an estimate of the true load-bearing area of the rock sample at any point along the post-failure curve of the sample. For the rock types used in the study, which were deformed to preselected positions along their respective post-failure curves and with the assumption that the fractured rock carried none of the applied load, the two techniques of measuring the effective load-bearing area give results which are equivalent.
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