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  • 1
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    Pamplona, España : Periodicals Archive Online (PAO)
    Persona y derecho. 22 (1990) 159 
    ISSN: 0211-4526
    Topics: Law
    Description / Table of Contents: PONENCIAS
    Notes: ACTAS DE LAS II JORNADAS INTERNACIONALES DE FILOSOFIA JURIDICA Y SOCIAL (I)
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  • 2
    Publication Date: 2017-03-06
    Description: The excellent spatial coverage of continuous GPS stations in the region affected by the Maule Mw = 8.8 2010 earthquake, combined with the proximity of the coast to the seismogenic zone, allows us to model megathrust afterslip on the plate interface with unprecedented detail. We invert post-seismic observations from continuous GPS sites to derive a time-variable model of the first 420 d of afterslip. We also invert co-seismic GPS displacements to create a new co-seismic slip model. The afterslip pattern appears to be transient and non-stationary, with the cumulative afterslip pattern being formed from afterslip pulses. Changes in static stress on the plate interface from the co- and post-seismic slip cannot solely explain the aftershock patterns, suggesting that another process – perhaps fluid related – is controlling the lower magnitude aftershocks. We use aftershock data to quantify the seismic coupling distribution during the post-seismic phase. Comparison of the post-seismic behaviour to interseismic locking suggests that highly locked regions do not necessarily behave as rate-weakening in the post-seismic period. By comparing the inter-seismic locking, co-seismic slip, afterslip, and aftershocks we attempt to classify the heterogeneous frictional behaviour of the plate interface.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2024-02-07
    Description: As the archetype of mountain building in subduction zones, the Central Andes has constituted an excellent example for investigating mountain-building processes for decades, but the mechanism by which orogenic growth occurs remains debated. In this study we investigate the Southern Central Andes, between 22° and 35°S, by examining the along-strike variations in Cenozoic uplift history (〈45 Ma) and the amount of tectonic shortening-thickening, allowing us to construct seven continental-scale cross-sections that are constrained by a new thermomechanical model. Our goal is to reconcile the kinematic model explaining crustal shortening-thickening and deformation with the geological constraints of this subduction-related orogen. To achieve this goal a representation of the thermomechanical structure of the orogen is constructed, and the results are applied to constrain the main decollement active for the last 15 Myr. Afterwards, the structural evolution of each transect is kinematically reconstructed through forward modeling, and the proposed deformation evolution is analyzed from a geodynamic perspective through the development of a numerical 2D geodynamic model of upper-plate lithospheric shortening. In this model, low-strength zones at upper-mid crustal levels are proposed to act both as large decollements that are sequentially activated toward the foreland and as regions that concentrate most of the orogenic deformation. As the orogen evolves, crustal thickening and heating lead to the vanishing of the sharp contrast between low- and high-strength layers. Therefore, a new decollement develops towards the foreland, concentrating crustal shortening, uplift and exhumation and, in most cases, focusing shallow crustal seismicity. The north-south decrease in shortening, from 325 km at 22°S to 46 km at 35°S, and the cumulated orogenic crustal thicknesses and width are both explained by transitional stages of crustal thickening: from pre-wedge, to wedge, to paired-wedge and, finally, to plateau stages.
    Type: Article , PeerReviewed
    Format: text
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  • 4
    Publication Date: 2012-02-25
    Description: SUMMARY We present an upgraded version of a previously published 3-D density model of the Andean subduction zone between 18°S and 45°S. This model consists of 3-D bodies of constant density, which geometry is constrained by independent seismic data and is triangulated from vertical cross-sections. These bodies define the first-order morphology and internal structure of the subducted Nazca slab and South American Plate. The new version of the density model results after forward modelling the Bouguer anomaly as computed from the most recent version of the Earth Gravitational Model (EGM2008). The 3-D density model incorporates new seismic information to better constrain the geometry of the subducted slab and continental Moho (CMH) and has a trench-parallel resolution doubling the resolution of the previous model. As an example of the potential utility of our model, we compare the geometry of the subducted slab and CMH against the corresponding global models Slab1.0 and Crust2.0, respectively. This exercise demonstrates that, although global models provide a good first-order representation of the slab and upper-plate crustal geometries, they show large discrepancies (up to ±40 km) with our upgraded model for some well-constrained areas. The geometries of the slab, lithosphere–asthenosphere boundary below the continent, CMH and intracrustal density discontinuity that we present here as Supporting Information can be used to study Andean geodynamic processes from a wide range of quantitative approaches.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 5
    Publication Date: 2012-07-01
    Description: The Andean fold-and-thrust belts of west-central Argentina (33°S and 36°S), above the normal subduction segment, present important along-strike variations in mean topographic uplift, structural elevation, amount and rate of shortening, and crustal root geometry. To analyze the controlling factors of these latitudinal changes, we compare these parameters and the chronology of deformation along 11 balanced crustal cross sections across the thrust belts between 70°W and 69°W, where the majority of the upper-crustal deformation is concentrated, and reconstruct the Moho geometry along the transects. We propose two models of crustal deformation: a 33°40′S model, where the locus of upper-crustal shortening is aligned with respect to the maximum crustal thickness, and a 35°40′S model, where the upper-crustal shortening is uncoupled from the lower-crustal deformation and thickening. This degree of coupling between brittle upper crust and ductile lower crust deformation has strong influence on mean topographic elevation. In the northern sector of the study area, an initial thick and felsic crust favors the coupling model, while in the southern sector, a thin and mafic lower crust allows the uncoupling model.Our results indicate that interplate dynamics may control the overall pattern of tectonic shortening; however, local variations in mean topographic elevation, deformation styles, and crustal root geometry are not fully explained and are more likely to be due to upper-plate lithospheric strength variations.
    Print ISSN: 0016-7606
    Electronic ISSN: 1943-2674
    Topics: Geosciences
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  • 6
    Publication Date: 2022-02-11
    Description: The Tolhuaca hydrothermal system is one of the few attested geothermal resources in Chile. While recent investigations provided some insights into the depth and temperature of the geothermal reservoirs and the chemical and mineralogical evolution of the hydrothermal system, little is still known about the CO2 degassing of the system and the local and shallow control of fluid pathways. Here, we document the soil CO2 degassing and soil temperature distributions in the southern part of the Tolhuaca hydrothermal system and at one of its northern fumaroles, and provide a first estimate of its total CO2 release. The surveyed area is responsible for a total CO2 emission of up to 30 t d-1. Hydrothermal CO2 emissions (~ 4-27 t d-1) are mostly restricted to the thermal manifestations or generally distributed along NNW trending lineaments, sharing the same orientation as the volcanic vents and thermal springs and fumaroles. Hydrothermal CO2 fluxes, fumaroles and thermal springs are generally encountered in topographic lows, in close vicinity of streams and often in clay-rich pyroclastic units, highlighting a relation between landscape evolution and the activity of the hydrothermal system. We suggest that glacial unloading and incision of the stream inside the clay-rich units have likely enhanced locally the permeability, creating a preferential pathway for the migration of deeper fluid to the surface. As several hydrothermal systems in the Andes are found on the flank of volcanoes hosting glaciers, we propose that they could have had a similar development to that of the Tolhuaca hydrothermal system.
    Description: Published
    Description: 107316
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: CO2 emission ; Tolhuaca volcano
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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