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  • 1
    Electronic Resource
    Electronic Resource
    Stress Field at a Transcurrent Plate Boundary in the Presence of Frictional Heat Production at Depth (1997)
    Springer
    Pure and applied geophysics 150 (1997), S. 181-201 
    Details
    ISSN: 1420-9136
    Keywords: Key words: Fault dislocation, frictional heat production rheology, stress field.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. —A model is proposed to study the modification of the stress field at a transcurrent plate boundary due to frictional heat production at depth. Two cases are considered a stable and a stretched lithosphere. The model is applied to those weak faults where the dynamic friction is small compared to a static one; if the deformation along the brittle portion of the fault is entirely accommodated by a series of seismic ruptures in a quasi-static state where the fault has been moving for millions of years, the long-term thermal field perturbation due to these ruptures results in only a few degrees and can be neglected. The boundary zone is considered as a viscoelastic body subject to a constant strain rate. The lower section of the boundary is assumed to slip aseismically along a vertical transcurrent fault and to completely accommodate the plate motion, while the upper section is locked. The slipping zone is divided into a semi-brittle zone, placed between the isothermal surfaces of 300°C and 450°C, and a ductile zone beneath. The frictional heat is calculated by assuming a linearly decreasing friction in the semi-brittle and a constant friction in the ductile zones. The heat modifies the temperature field, producing an upward movement of the semi-brittle and ductile fault sections. As a consequence, the thickness of the brittle fault section is reduced and friction at the base of this section is less. The stress field in the boundary zone is calculated as a function of time for different friction profiles and slip rates on the fault. Owing to heat production, a greater stress concentration is produced on the brittle fault section, while shear stress is lowered in regions occupied by the uplifted semi-brittle layer. These effects are found to be remarkable only in the case of a stable zone, with a standard unperturbed geotherm, while they are irrelevant in a stretched zone with a high geothermal gradient. In any case, the role of the semi-brittle layer appears to be more prominent in the case of boundaries with higher slip rates, due to the presence of higher stress values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000240050072
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  • 2
    Electronic Resource
    Electronic Resource
    Heat flow in Italy (1978)
    Springer
    Pure and applied geophysics 117 (1978), S. 135-149 
    Details
    ISSN: 1420-9136
    Keywords: Heat flow corrections ; Heat flow and tectonic features ; Mediterranean plate tectonics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract More than fifty heat flow measurements in Italy are examined. The values, corrected only for local influences (when present), are related to the main geological features with the following results: foreland areas, 55±19 mW m−2, foredeep areas, 45±21 mW m−2; folded regions and intermountain depressions, 76±29 mW m−2. In volcanic areas the heat flow rises to in excess of 600 mW m−2. From a tectonic point of view, these values are consistent with the hypothesis that the Apennine chain is intersected by two arcuate structures: the first from Liguria to Latium is very probably a continental arc, that is an are which occurs within a continent, and the second from Campania to Calabria is very similar from geophysical evidence to the classic island arcs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879741
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of stresses in two geodynamically different areas: Stable foreland and extensional backarc (1996)
    Springer
    Pure and applied geophysics 146 (1996), S. 319-341 
    Details
    ISSN: 1420-9136
    Keywords: Stress evolution ; geothermal profiles ; shear zone rheology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Areas which are geodynamically different have different behaviors both in their thermal regime and seismic activity. A stable area has a geotherm which can be considered as standard, extensional and compressional areas have, respectively, high and low temperature gradients. The Italian region includes different geodynamical areas and all such situations are present. We consider the Apulian platform as an example of a stable area and the Tuscany-Latium as an example of an extensional area. For both of them the present geotherms are calculated, taking into account, for the Tuscany-Latium, its thermal history. Assuming that each region is subject to a constant strain rate, the stresses are calculated as functions of depth and time. The rheological behavior is assumed to be linear viscoelastic, with viscosity dependent on temperature and elastic parameters dependent on lithology. The geothermal profile and the rheological structure of the lithosphere remarkably affect the processes of stress accumulation which control the distribution of seismic activity. The abrupt decrease of the temperature gradient at the Moho produces considerably higher stress values with respect to the case of uniform gradient, thus favoring subcrustal seismicity. In the case of a standard temperature gradient, subcrustal seismicity is predicted and a gap in seismicity, indicating a soft intracrustal layer, exists if there is a discontinuity in rheology. By contrast, in the case of a high-temperature gradient, subcrustal seismicity is not to be expected, even in the presence of a discontinuity in rheology, since subcrustal temperatures are already too high to permit a sufficient stress accumluation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876496
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  • 4
    Electronic Resource
    Electronic Resource
    A method for the determination of the thermal properties of soil near the surface (1971)
    Springer
    Meteorology and atmospheric physics 20 (1971), S. 35-42 
    Details
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Es wird eine neue Methode beschrieben, die auf der Heizung der Bodenoberfläche durch eine flache elektrische Drahtspirale und auf der Aufzeichnung des Temperaturanstiegs beruht. Diese Methode hat vor allem folgende Vorzüge: Ausschaltung des unvollständigen Kontakts zwischen Boden und Wärmequelle und kurze Dauer des Experiments. Die Anwendung der Methode wird durch Laboratoriums-experiments wie auch durch Naturversuche demonstriert.
    Abstract: Résumé On montre une nouvelle méthode qui consiste dans le réchauffement de la surface du sol par une spirale plate de fil conducteur et dans l'enregistrement de l'augmentation de la température à petite profondeur. La méthode montre surtout les advantages suivents: élimination de la résistence de contact entre le sol et la source et la durée limitée de l'expérience. L'application de la méthode est démontré par des expériences de laboratoire et par des expériences en nature.
    Notes: Summary A new method, based on the heating of the soil surface by a flat spiral of electric wire and on the record of temperature rise at a shallow depth, is described. The method has mainly the following favourable features: elimination of the imperfect soil-to-source contact and short duration of the experiment. The application of the method is demonstrated by laboratory experiments as well as by experiments “in situ”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247746
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of accurate heat flux measurements on the evaluation of evaporation from a bare soil by energy balance (1978)
    Springer
    Meteorology and atmospheric physics 27 (1978), S. 155-169 
    Details
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Genaue Messungen der thermischen Leitfähigkeit und der Diffusion, die auf der Boden-oberfläche mit einer flachen Heizquelle und in verschiedenen Tiefen mit zylindrischen Wärmequellen durchgeführt worden sind, haben eine bessere Schätzung des Wärmeflusses im Boden ermöglicht. Es wurde festgestellt, daß der Wärmefluß eine wichtige Komponente der Energiebilanz in einem aperen Boden über ein kurzes Zeitintervall hinweg (1 Stunde) ist. Tatsächlich kann, wenn Verdunstung auftritt und der Bodenwassergehalt gering ist, der Wärmefluß einen Spitzenwert von 25% der Strahlungsbilanz erreichen und, wenn die Verdunstungswärme Null ist, kann er einen Wert etwas über 40% erreichen (dies ist im allgemeinen wenige Stunden nach Sonnenaufgang oder vor Sonnenuntergang der Fall). Folglich ist die Schätzung der Verdunstungswärme aus der Energiebilanz mehr realistisch, wenn der Wert des Wärmeflusses in Boden nicht unsicher ist, vorausgesetzt, daß alle anderen Komponenten bekannt oder meßbar sind.
    Notes: Summary Accurate measurements of thermal conductivity and diffusivity, made both at soil surface by a flat heater and at various depths by cylindrical heat sources, had allowed a better estimation of soil heat flux. It was seen that heat flux is an important component in the energy balance for a bare soil over a short time interval (as 1 hr): indeed, when the driving force of evaporation is active and soil water content is low, heat flux may reach the peak value of 25 percent of net radiation, and, when the evaporative heat is zero, it may reach a value slightly more than 40 percent (generally, this is noted few hours after sunrise or before sunset). Subsequently, the estimate of the evaporative heat by energy balance is more realistic if the value of soil heat flux is not ambiguous, provided that all other components are known or measurable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246692
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  • 6
    Electronic Resource
    Electronic Resource
    The contemporary effect of erosion/sedimentation and past climate on the geothermal gradient (1993)
    Springer
    Studia geophysica et geodaetica 37 (1993), S. 258-264 
    Details
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Summary The aim of this paper is to calculate the correction that must be applied to the observed geothermal gradient when it is affected by a disturbance due to the contemporary effects of erosion/sedimentation and past climatic changes. This problem is treated by integrating the equation of heat conduction in a moving homogeneous medium (which accounts for the erosion/sedimentation process) with the boundary condition that the surface temperature undergoes a sinusoidal variation in time. The solution shows that the whole disturbance in the soil temperature at any depth is the sum of two terms which represent, separately, the effects of erosion/sedimentation and that of past climatic changes. The disturbance can thus be removed from the geothermal gradient by applying separately the respective corrections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01624599
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  • 7
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    Influence of accurate heat flux measurements on the evaluation of evaporation from a bare soil by energy balance (1978)
    Springer
    Details
    Publication Date: 1978-06-01
    Print ISSN: 0177-7971
    Electronic ISSN: 1436-5065
    Topics: Geography , Physics
    Published by Springer
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  • 8
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    A method for the determination of the thermal properties of soil near the surface (1971)
    Springer
    Details
    Publication Date: 1971-03-01
    Print ISSN: 0177-7971
    Electronic ISSN: 1436-5065
    Topics: Geography , Physics
    Published by Springer
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  • 9
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    Stress Field at a Transcurrent Plate Boundary in the Presence of Frictional Heat Production at Depth (1997)
    Springer
    Details
    Publication Date: 1997-10-01
    Print ISSN: 0033-4553
    Electronic ISSN: 1420-9136
    Topics: Geosciences , Physics
    Published by Springer
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  • 10
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    Heat flow in Italy (1978)
    Springer
    Details
    Publication Date: 1978-01-01
    Print ISSN: 0033-4553
    Electronic ISSN: 1420-9136
    Topics: Geosciences , Physics
    Published by Springer
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