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  • 1
    Electronic Resource
    Electronic Resource
    A functional equation approach to the theory of production, technical change, and invariance (1984)
    Springer
    Journal of economics 44 (1984), S. 177-187 
    Details
    ISSN: 1617-7134
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Conclusion The goal of this paper was to reconsider the properties of production and technical change functions using functional equations. More specifically, the properties of associativity and composition, and the existence of inverse and identity transformations were imposed on the technical change functions and it was learned that all of these properties could be satisfied without imposing differentiability. This is a meaningful result; there is no reason to believe that technical change occurs in a smooth, differentiable, manner. However, when the holotheticity, or invariance, of a production function under technical change was investigated, differentiability was required in order to derive the holothetic technology, givenφ (x, t). This is certainly disappointing for those who desire to impose only the most general and least restrictive conditions, but it provides support for the claim that tractable analysis requires differentiability. Given this apparent necessity of differentiability, it must be concluded that the best method for identifying the holothetic production function, given a particular technical change functionφ, is the solution of a partial differential equation, and Sato (1980, 1981) provides this solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01289476
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    Paper (German National Licenses)
    Fulltext
  • 2
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    The Relationship Between Microfracture Damage and the Physical Properties of Fault-Related Rocks: The Gole Larghe Fault Zone, Italian Southern Alps (2019)
    Details
    Publication Date: 2020-11-26
    Description: Although geological, seismological, and geophysical evidence indicates that fracture damage and physical properties of fault‐related rocks are intimately linked, their relationships remain poorly constrained. Here we correlate quantitative observations of microfracture damage within the exhumed Gole Larghe Fault Zone (Italian Southern Alps) with ultrasonic wave velocities and permeabilities measured on samples collected along a 1.5‐km‐long transect across the fault zone. Ultrasonic velocity and permeability correlate systematically with the measured microfracture intensity. In the center of the fault zone where microfractures were pervasively sealed, P wave velocities are the highest and permeability is relatively low. However, neither the crack porosity nor the permeability derived by modeling the velocity data using an effective‐medium approach correlates well with the microstructural and permeability measurements, respectively. The applied model does not account for sealing of microfractures but assumes that all variations in elastic properties are due to microfracturing. Yet we find that sealing of microfractures affects velocities significantly in the more extensively altered samples. Based on the derived relationships between microfracture damage, elastic and hydraulic properties, and mineralization history, we (i) assess to what extent wave velocities can serve as a proxy for damage structure and (ii) use results on the present‐day physical and microstructural properties to derive information about possible postseismic recovery processes. Our estimates of velocity changes associated with sealing of microfractures quantitatively agree with seismological observations of velocity recovery following earthquakes, which suggests that the recovery is at least in part due to the sealing of microfractures.
    Description: Published
    Description: 7661-7687
    Description: 3T. Sorgente sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Influence of Effective Stress and Pore Fluid Pressure on Fault Strength and Slip Localization in Carbonate Slip Zones (2021)
    Wiley Agu
    Details
    Publication Date: 2021-06-16
    Description: The presence of pressurized fluids influences the mechanical behavior of faults. To test the roles of normal stress and fluid pressure on shear strength and localization behavior of calcite gouges, we conducted a series of rotary-shear experiments with pore fluid pressures up to 10.5 MPa and difference between normal stress and fluid pressure up to 11.2 MPa. Calcite gouges were sheared for displacements of 0.3 m to several meters at slip rates of 1 mm/s and 1 m/s. Drainage conditions in experiments were constrained from estimates of the hydraulic diffusivity. Gouges were found to be drained at 1 mm/s, but possibly partially undrained during sliding at 1 m/s. Shear strength obeys an effective-stress law with an effective-stress coefficient close to unity with a friction coefficient of ~0.7 that decreases to 0.19 due to dynamic weakening. The degree of comminution and slip localization constrained from experimental microstructures depends on the effective normal stress. Slip localization in calcite gouges does not occur at low effective normal stress. The presence of pore fluids lowers the shear strength of gouges sheared at 1 mm/s and causes an accelerated weakening at 1 m/s compared to dry gouges, possibly due to enhanced subcritical crack growth and intergranular lubrication. Thermal pressurization occurs only after dynamic weakening when friction is generally low and relatively independent of normal stress and therefore unaffected by thermal pressurization. The experimental results are consistent with the view that the presence of pressurized fluid in carbonate-bearing faults can facilitate earthquake nucleation.
    Description: ERC StG 205175 USEMS ERC CoG 614705 NOFEAR Ca.Ri.Pa.Ro Foundation Gesellschaft der Freunde der Ruhr‐Universität Bochum e.V.
    Description: Published
    Description: e2020JB019805
    Description: 3T. Sorgente sismica
    Description: JCR Journal
    Keywords: Fault ; Earthquakes ; Carbonates ; Gouges ; Earthquake mechanics ; Rock Friction
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Earthquake lubrication and healing explained by amorphous nanosilica (2020)
    id 320
    Details
    Publication Date: 2021-06-30
    Description: During earthquake propagation, geologic faults lose their strength, then strengthen as slip slows and stops. Many slip-weakening mechanisms are active in the upper-mid crust, but healing is not always well-explained. Here we show that the distinct structure and rate-dependent properties of amorphous nanopowder (not silica gel) formed by grinding of quartz can cause extreme strength loss at high slip rates. We propose a weakening and related strengthening mechanism that may act throughout the quartz-bearing continental crust. The action of two slip rate-dependent mechanisms offers a plausible explanation for the observed weakening: thermally-enhanced plasticity, and particulate flow aided by hydrodynamic lubrication. Rapid cooling of the particles causes rapid strengthening, and inter-particle bonds form at longer timescales. The timescales of these two processes correspond to the timescales of post-seismic healing observed in earthquakes. In natural faults, this nanopowder crystallizes to quartz over 10s–100s years, leaving veins which may be indistinguishable from common quartz veins.
    Description: Published
    Description: 3T. Sorgente sismica
    Description: 2IT. Laboratori analitici e sperimentali
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Static versus dynamic fracturing in shallow carbonate fault zones (2018)
    Details
    Publication Date: 2020-12-21
    Description: Moderate to large earthquakes often nucleate within and propagate through carbonates in the shallow crust. The occurrence of thick belts of low-strain fault-related breccias is relatively common within carbonate damage zones and was generally interpreted in relation to the quasi-static growth of faults. Here we report the occurrence of hundreds of meters thick belts of intensely fragmented dolostones along a major transpressive fault zone in the Italian Southern Alps. These fault rocks have been shattered in-situ with negligible shear strain accumulation. The conditions of in-situ shattering were investigated by deforming the host dolostones in uniaxial compression both under quasi-static (strain rate ∼10−5 s−1) and dynamic (strain rate 〉50 s−1) loading. Dolostones deformed up to failure under low-strain rate were affected by single to multiple discrete extensional fractures sub-parallel to the loading direction. Dolostones deformed under high-strain rate were shattered above a strain rate threshold of ∼120 s−1 and peak stresses on average larger than the uniaxial compressive strength of the rock, whereas they were split in few fragments or remained macroscopically intact at lower strain rates. Fracture networks were investigated in three dimensions showing that low- and high-strain rate damage patterns (fracture intensity, aperture, orientation) were significantly different, with the latter being similar to that of natural in-situ shattered dolostones (i.e., comparable fragment size distributions). In-situ shattered dolostones were thus interpreted as the result of high energy dynamic fragmentation (dissipated strain energies 〉1.8 MJ/m3) similarly to pulverized rocks in crystalline lithologies. Given their seismic origin, the presence of in-situ shattered dolostones can be used in earthquake hazard studies as evidence of the propagation of seismic ruptures at shallow depths.
    Description: Published
    Description: 8-19
    Description: 7T. Struttura della Terra e geodinamica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Influence of Effective Stress and Pore Fluid Pressure on Fault Strength and Slip Localization in Carbonate Slip Zones (2021)
    Details
    Publication Date: 2021-07-04
    Description: The presence of pressurized fluids influences the mechanical behavior of faults. To test the roles of normal stress and fluid pressure on shear strength and localization behavior of calcite gouges, we conducted a series of rotary‐shear experiments with pore fluid pressures up to 10.5 MPa and difference between normal stress and fluid pressure up to 11.2 MPa. Calcite gouges were sheared for displacements of 0.3 m to several meters at slip rates of 1 mm/s and 1 m/s. Drainage conditions in experiments were constrained from estimates of the hydraulic diffusivity. Gouges were found to be drained at 1 mm/s, but possibly partially undrained during sliding at 1 m/s. Shear strength obeys an effective‐stress law with an effective‐stress coefficient close to unity with a friction coefficient of ~0.7 that decreases to 0.19 due to dynamic weakening. The degree of comminution and slip localization constrained from experimental microstructures depends on the effective normal stress. Slip localization in calcite gouges does not occur at low effective normal stress. The presence of pore fluids lowers the shear strength of gouges sheared at 1 mm/s and causes an accelerated weakening at 1 m/s compared to dry gouges, possibly due to enhanced subcritical crack growth and intergranular lubrication. Thermal pressurization occurs only after dynamic weakening when friction is generally low and relatively independent of normal stress and therefore unaffected by thermal pressurization. The experimental results are consistent with the view that the presence of pressurized fluid in carbonate‐bearing faults can facilitate earthquake nucleation.
    Description: Key Points: Normal stress and fluid pressure equally affect shear strength of calcite gouges at relatively low effective normal stresses (≤11 MPa). The degree of slip localization in calcite gouges sheared at seismic slip rates increases with effective normal stress. Thermal pressurization has small effect on shear stress as it occurs after change from pressure‐ to temperature‐controlled slip behavior.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Keywords: 551.8 ; rotary‐shear experiments ; calcite gouges ; seismic slip rates ; strain localization ; effective‐pressure law ; microstructures
    Type: article
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    CITATION GEO-LEO
  • 7
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    Structural Evolution of a Crustal-Scale Seismogenic Fault in a Magmatic Arc: The Bolfin Fault Zone (Atacama Fault System) (2022)
    Wiley-AGU
    Details
    Publication Date: 2022-02-28
    Description: How major crustal-scale seismogenic faults nucleate and evolve in crystalline basements represents a long-standing, but poorly understood, issue in structural geology and fault mechanics. Here, we address the spatio-temporal evolution of the Bolfin Fault Zone (BFZ), a 〉40-km-long exhumed seismogenic splay fault of the 1000-km-long strike-slip Atacama Fault System. The BFZ has a sinuous fault trace across the Mesozoic magmatic arc of the Coastal Cordillera (Northern Chile) and formed during the oblique subduction of the Aluk plate beneath the South American plate. Seismic faulting occurred at 5-7 km depth and ≤ 300°C in a fluid-rich environment as recorded by extensive propylitic alteration and epidote-chlorite veining. Ancient (125-118 Ma) seismicity is attested by the widespread occurrence of pseudotachylytes. Field geologic surveys indicate nucleation of the BFZ on precursory geometrical anisotropies represented by magmatic foliation of plutons (northern and central segments) and andesitic dyke swarms (southern segment) within the heterogeneous crystalline basement. Seismic faulting exploited the segments of precursory anisotropies that were optimal to favorably oriented with respect to the long-term far-stress field associated with the oblique ancient subduction. The large-scale sinuous geometry of the BFZ resulted from the hard linkage of these anisotropy-pinned segments during fault growth.
    Description: European Research Council Project (NOFEAR) 614705
    Description: Published
    Description: e2021TC006818
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Atacama Fault System; fault growth; intra‐arc deformation; pseudotachylytes; seismogenic fault; structural inheritance ; Solid Earth
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Frictional Melting in Hydrothermal Fluid-Rich Faults: Field and Experimental Evidence From the Bolfín Fault Zone (Chile) (2021)
    Wiley-AGU
    Details
    Publication Date: 2021-12-16
    Description: Tectonic pseudotachylytes are thought to be unique to certain water-deficient seismogenic environments and their presence is considered to be rare in the geological record. Here, we present field and experimental evidence that frictional melting can occur in hydrothermal fluid-rich faults hosted in the continental crust. Pseudotachylytes were found in the 〉40 km-long Bolfín Fault Zone of the Atacama Fault System, within two ca. 1 m-thick (ultra)cataclastic strands hosted in a damage-zone made of chlorite-epidote-rich hydrothermally altered tonalite. This alteration state indicates that hydrothermal fluids were active during the fault development. Pseudotachylytes, characterized by presenting amygdales, cut and are cut by chlorite-, epidote- and calcite-bearing veins. In turn, crosscutting relationship with the hydrothermal veins indicates pseudotachylytes were formed during this period of fluid activity. Rotary shear experiments conducted on bare surfaces of hydrothermally altered rocks at seismic slip velocities (3 m s-1) resulted in the production of vesiculated pseudotachylytes both at dry and water-pressurized conditions, with melt lubrication as the primary mechanism for fault dynamic weakening. The presented evidence challenges the common hypothesis that pseudotachylytes are limited to fluid-deficient environments, and gives insights into the ancient seismic activity of the system. Both field observations and experimental evidence, indicate that pseudotachylytes may easily be produced in hydrothermal environments, and could be a common co-seismic fault product. Consequently, melt lubrication could be considered one of the most efficient seismic dynamic weakening mechanisms in crystalline basement rocks of the continental crust.
    Description: The authors would like to acknowledge the support of ERC CoG No 614705 NOFEAR. R. Gomila has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska- Curie grant agreement No 896346 – FRICTION.
    Description: Published
    Description: e2021GC009743
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Atacama fault system; fluid‐rich faults; frictional melting; tectonic pseudotachylytes; vesiculation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Along-strike architectural variability of an exhumed crustal-scale seismogenic fault (Bolfin Fault Zone, Atacama Fault System, Chile) (2023)
    Elsevier
    Details
    Publication Date: 2023-02-07
    Description: Fault zone architecture and its internal structural variability play a pivotal role in earthquake mechanics, by controlling, for instance, the nucleation, propagation and arrest of individual seismic ruptures and the evolution in space and time of foreshock and aftershock seismic sequences. Nevertheless, the along-strike architectural variability of crustal-scale seismogenic sources over regional distances is still poorly investigated. Here, we describe the architectural variability of the 〉40-km-long exhumed, seismogenic Bolfin Fault Zone (BFZ) of the intra-arc Atacama Fault System (Northern Chile). The BFZ cuts through plutonic rocks of the Mesozoic Coastal Cordillera and was seismically active at 5–7 km depth and ≤ 300 °C in a fluid-rich environment. The BFZ includes multiple altered fault core strands, consisting of chlorite-rich cataclasites-ultracataclasites and pseudotachylytes, surrounded by chlorite-rich protobreccias to protocataclasites over a zone up to 60-m-thick. These fault rocks are embedded within a low-strain damage zone, up to 150-m-thick, which includes strongly altered volumes of dilatational hydrothermal breccias and clusters of epidote-rich fault-vein networks at the linkage of the BFZ with subsidiary faults. The strong hydrothermal alteration of rocks along both the fault core and the damage zone attests to an extensive percolation of fluids across all the elements of the structural network during the activity of the entire fault zone. In particular, we interpret the epidote-rich fault-vein networks and associated breccias as an exhumed example of upper-crustal fluid-driven earthquake swarms, similar to the presently active intra-arc Liquiñe-Ofqui Fault System (Southern Andean Volcanic Zone, Chile).
    Description: European Research Council Consolidator Grant Project (NOFEAR) No 614705
    Description: Published
    Description: 104745
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Atacama fault system ; Earthquakes ; Fault structure ; Fault zone rocks ; Fluid-driven seismicity ; Seismogenic faults ; 04. Solid Earth
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Friction Experiments on Lunar Analog Gouges and Implications for the Mechanism of the Apollo 17 Long Runout Landslide (2024)
    Wiley-Agu
    Details
    Publication Date: 2024-03-19
    Description: The Light Mantle landslide is a hypermobile landslide on the Moon. Apollo 17 astronauts collected a core sample of the top 60 cm of the Light Mantle deposit, which is currently being analyzed as part of the NASA's Apollo Next Generation Sample Analysis program. The origin of its hypermobility remains undetermined, as the proposed mechanisms are difficult to prove because of the lack of theoretical and experimental support and the scarcity of field data related to the internal structures of its deposit. Regardless of the emplacement mechanisms, it has been proposed that localized dynamic frictional weakening is responsible for the early stage instability that leads to catastrophic failure. Here, we conduct friction experiments under vacuum to investigate the viability of dynamic friction weakening in lunar analog anorthosite-bearing gouges (i.e., rock powders). Our results show that localized dynamic friction weakening does not occur in these gouges at loading conditions where, instead, weakening is observed in other materials on Earth. Therefore, possibly other fluidization-related mechanisms contributed to the initiation of the hypermobile Light Mantle landslide. Finally, we describe the microstructures formed in the experiments, including the presence of clast cortex aggregates. Preliminary investigation of the Light Mantle core samples (73001/73002) shows the presence of similar microstructures. Therefore, our microstructural observations will help the analysis and interpretation of the Apollo 17 core samples, as keys to insights about internal processes occurring during the emplacement of the landslide.
    Description: Published
    Description: e2022JE007520
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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