Modelado de efectos de carga en la Patagonia austral

Los Campos de Hielo Patagónico, las masas de hielo extrapolar mas grandes en el hemisferio sur, se encuentran afectadas por una compleja estructura tectónico-reológica, un intenso ajuste glacio-isostático y un rápido retroceso glaciar. El trabajo de investigación desarrollado tiene, como objetivo general, el avance del conocimiento de los procesos geodinámicos en la región de la Patagonia austral en base al modelado de efectos de la respuesta elástica a cambios de masa superficial: deformación elástica de la corteza, cambios en el campo gravitatorio, deformación y desplazamiento de las superficies equipotenciales, inclinaciones de las superficie terrestre y equipotenciales. Este proyecto incluye el desarrollo de herramientas de cálculo; la compilación de modelos regionales de carga; la integración, interpretación y síntesis de los resultados del modelado. Estos modelados comprenden la respuesta elástica a los cambios actuales de la masa de hielo en el sur de la Patagonia; los efectos de la carga elástica derivados de distintos escenarios de carga hidrológica, incluyendo las rupturas del endicamiento de los brazos Rico y Sur del lago Argentino producto del avance del glacial Perito Moreno y las previstas represas del Río Santa Cruz. Así mismo, se presentan también resultados para la carga oceánica, su uso para la validación de los cálculos y carga atmosférica. Los efectos modelados se integran en modelos regionales, que posibilitan la comparación con observaciones geodésicas y geofísicas. De esta manera se obtiene nueva información sobre las propiedades reológicas de la corteza y se aporta al conocimiento de los procesos geodinámicos efectivos en la región. Estos resultados se evalúan con respecto a los observables geodésicos y su potencial para validar o acotar modelos de tierra elástica. Se discute las consecuencias para la determinación de las tasas de deformación precisas, el alcance para nuestra comprensión del intenso levantamiento observado en el Campo de Hielo Patagónico Sur, y los requisitos y perspectivas de una observación geodésica de los efectos de carga elásticos para el conocimiento de partes de la estructura terrestre. Por lo que los resultados contribuyen a la explicación causal de efectos observados por distintos métodos y permiten recomendaciones concretas para futuros estudios de determinados efectos de carga u otros efectos geodinámicos.Facultad de Ciencias Astronómicas y Geofísica

Mantle Flow Pattern Associated With the Patagonian Slab Window Determined From Azimuthal Anisotropy

Geological processes in Southern Patagonia are affected by the Patagonian slab window, formed by the subduction of the Chile Ridge and subsequent northward migration of the Chile Triple Junction. Using shear wave splitting analysis, we observe strong splitting of up to 2.5 s with an E-W fast direction just south of the triple junction and the edge of the subducting Nazca slab. This region of strong anisotropy is coincident with low uppermost mantle shear velocities and an absence of mantle lithosphere, indicating that the mantle flow occurs in a warm, low-viscosity, 200–300 km wide shallow mantle channel just to the south of the Nazca slab. The region of flow corresponds to a volcanic gap caused by depleted mantle compositions and absence of slab-derived water. In most of Patagonia to the south of this channel, splitting fast directions trend NE-SW consistent with large-scale asthenospheric flow.Fil: Ben Mansour, Walid. Washington University in St. Louis; Estados UnidosFil: Wiens, Douglas A.. Washington University in St. Louis; Estados UnidosFil: Mark, Hannah F.. Washington University in St. Louis; Estados UnidosFil: Russo, Raymond M.. University of Florida; Estados UnidosFil: Richter, Andreas Jorg. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; ArgentinaFil: Marderwald, Eric Rodolfo. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Barrientos, Sergio. Universidad de Chile; Chil

The rapid and steady mass loss of the patagonian icefields throughout the GRACE Era: 2002-2017

We use the complete gravity recovery and climate experiment (GRACE) Level-2 monthly time series to derive the ice mass changes of the Patagonian Icefields (Southern Andes). The glacial isostatic adjustment is accounted for by a regional model that is constrained by global navigation satellite systems (GNSS) uplift observations. Further corrections are applied concerning the effect of mass variations in the ocean, in the continental water storage, and of the Antarctic ice sheet. The 161 monthly GRACE gravity field solutions are inverted in the spatial domain through the adjustment of scaling factors applied to a-priori ice mass change patterns based on published remote sensing results for the Southern and Northern Patagonian Icefields, respectively. We infer an ice mass change rate of -24.4 ± 4.7 Gt/a for the Patagonian Icefields between April 2002 and June 2017, which corresponds to a contribution to the eustatic sea level rise of 0.067 ± 0.013 mm/a. Our time series of monthly ice mass changes reveals no indication for an acceleration in ice mass loss. We find indications that the Northern Patagonian Icefield contributes more to the integral ice loss than previously assumed.Fil: Richter, Andreas Jorg. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Technische Universität Dresden; AlemaniaFil: Groh, Andreas. Technische Universität Dresden; AlemaniaFil: Horwath, Martin. Technische Universität Dresden; AlemaniaFil: Ivins, Erik. California Institute of Technology; Estados UnidosFil: Marderwald, Eric Rodolfo. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Hormaechea, José Luis. Estacion Astronomica Rio Grande; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Perdomo, Raúl. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Dietrich, Reinhard. Technische Universität Dresden; Alemani

Lithospheric erosion in the Patagonian slab window, and implications for glacial isostasy

Author Posting. © American Geophysical Union, 2022. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 49(2), (2022): e2021GL096863, https://doi.org/10.1029/2021GL096863.The Patagonian slab window has been proposed to enhance the solid Earth response to ice mass load changes in the overlying Northern and Southern Patagonian Icefields (NPI and SPI, respectively). Here, we present the first regional seismic velocity model covering the entire north-south extent of the slab window. A slow velocity anomaly in the uppermost mantle indicates warm mantle temperature, low viscosity, and possibly partial melt. Low velocities just below the Moho suggest that the lithospheric mantle has been thermally eroded over the youngest part of the slab window. The slowest part of the anomaly is north of 49°S, implying that the NPI and the northern SPI overlie lower viscosity mantle than the southern SPI. This comprehensive seismic mapping of the slab window provides key evidence supporting the previously hypothesized connection between post-Little Ice Age anthropogenic ice mass loss and rapid geodetically observed glacial isostatic uplift (≥4 cm/yr).The facilities of the IRIS Consortium are supported by the National Science Foundation’s SAGE Award under Cooperative Support Agreement EAR-1851048. The GUANACO project is funded by the National Science Foundation under grants EAR-1714154 to WUSTL and EAR-1714662 to SMU, and Erik R. Ivins was supported by NASA under grant NNH19ZDA001N-GRACEFO.2022-07-1

Towards a tidal loading model for the Argentine-German Geodetic Observatory (La Plata)

We present a regionalized model of ocean tidal loading effects for the Argentine-German Geodetic Observatory in La Plata. It provides the amplitudes and phases of gravity variations and vertical deformation for nine tidal constituents to be applied as corrections to the observatory’s future geodetic observation data. This model combines a global ocean tide model with a model of the tides in the Río de la Plata estuary. A comparison with conventional predictions based only on the global ocean tide model reveals the importance of the incorporation of the regional tide model. Tidal loading at the observatory is dominated by the tides in the Atlantic Ocean. An additional contribution of local tidal loading in channels and groundwater is examined. The magnitude of the tidal loading is also reviewed in the context of the effects of solid earth tides, atmospheric loading and non-tidal loadsFacultad de Ciencias Naturales y Muse

Towards a tidal loading model for the Argentine-German Geodetic Observatory (La Plata)

We present a regionalized model of ocean tidal loading effects for the Argentine-German Geodetic Observatory in La Plata. It provides the amplitudes and phases of gravity variations and vertical deformation for nine tidal constituents to be applied as corrections to the observatory’s future geodetic observation data. This model combines a global ocean tide model with a model of the tides in the Río de la Plata estuary. A comparison with conventional predictions based only on the global ocean tide model reveals the importance of the incorporation of the regional tide model. Tidal loading at the observatory is dominated by the tides in the Atlantic Ocean. An additional contribution of local tidal loading in channels and groundwater is examined. The magnitude of the tidal loading is also reviewed in the context of the effects of solid earth tides, atmospheric loading and non-tidal loadsFacultad de Ciencias Naturales y Muse

Horizontal and vertical deformation rates linked to the Magallanes‐Fagnano Fault, Tierra del Fuego: Reconciling geological and geodetic observations by modeling the current seismic cycle

We integrate geodetic, geological and seismological observations in Tierra del Fuego,into a consistent and quantitative analysis, to better understand the current crustaldeformation associated to the Magallanes-Fagnano Fault, i.e., the transform boundarybetween the South American and Scotia plates at the southern tip of Patagonia. Toobtain reliable geodetic estimates of the thickness of the seismogenic layer, we modelthe current seismic cycle from the great 1949 Mw 7.7 earthquake to the present,including the lasting effects of postseismic relaxation. The model parameters are con-strained by GNSS velocities obtained by reprocessing 24 years of observations in theisland with up-to-date models and satellite products. We combine the observed de-formation rates with long-term geological estimates of the slip rate in this transformsystem during the Holocene. The modeling results point to a seismogenic layer thick-ness of 15 ± 3 km and to fault planes inclined 63◦ ± 4◦ , dipping to the South. Alongthe sections of the Magallanes-Fagnano Fault in the island these results are consistentwith a seismic moment deficit rate, per unit of length, of 3.2±0.8×1012 N m a−1 km−1,and a cumulative seismic moment, to date, equivalent to an earthquake of magnitudeMw ´7. The postseismic viscoelastic relaxation, probably related to viscous flow inthe mantle, affects the entire region up to ∼ 200 km away from the Magallanes-FagnanoFault, and more than 60 years after the earthquake.Fil: Mendoza, Luciano Pedro Oscar. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Departamento de Astrometría; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Richter, Andreas Jorg. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Departamento de Astrometría; Argentina. Technische Universität Dresden; AlemaniaFil: Marderwald, Eric Rodolfo. Universidad Nacional de la Plata. Facultad de Cs.astronomicas y Geofisicas. Laboratorio Maggia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Departamento de Astrometría; ArgentinaFil: Hormaechea, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Estación Astronómica Río Grande; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Connon, Gerardo Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Estación Astronómica Río Grande; ArgentinaFil: Scheinert, M.. Technische Universität Dresden; AlemaniaFil: Dietrich, R.. Technische Universität Dresden; AlemaniaFil: Perdomo, Raul Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentin

The Rapid and Steady Mass Loss of the Patagonian Icefields throughout the GRACE Era: 2002–2017

We use the complete gravity recovery and climate experiment (GRACE) Level-2 monthly time series to derive the ice mass changes of the Patagonian Icefields (Southern Andes). The glacial isostatic adjustment is accounted for by a regional model that is constrained by global navigation satellite systems (GNSS) uplift observations. Further corrections are applied concerning the effect of mass variations in the ocean, in the continental water storage, and of the Antarctic ice sheet. The 161 monthly GRACE gravity field solutions are inverted in the spatial domain through the adjustment of scaling factors applied to a-priori ice mass change patterns based on published remote sensing results for the Southern and Northern Patagonian Icefields, respectively. We infer an ice mass change rate of −24.4 ± 4.7 Gt/a for the Patagonian Icefields between April 2002 and June 2017, which corresponds to a contribution to the eustatic sea level rise of 0.067 ± 0.013 mm/a. Our time series of monthly ice mass changes reveals no indication for an acceleration in ice mass loss. We find indications that the Northern Patagonian Icefield contributes more to the integral ice loss than previously assumed.Laboratorio de Meteorología espacial, Atmósfera terrestre, Geodesia, Geodinámica, diseño de Instrumental y Astrometrí

Towards a tidal loading model for the Argentine-German Geodetic Observatory (La Plata)

We present a regionalized model of ocean tidal loading effects for the Argentine-German Geodetic Observatory in La Plata. It provides the amplitudes and phases of gravity variations and vertical deformation for nine tidal constituents to be applied as corrections to the observatory’s future geodetic observation data. This model combines a global ocean tide model with a model of the tides in the Río de la Plata estuary. A comparison with conventional predictions based only on the global ocean tide model reveals the importance of the incorporation of the regional tide model. Tidal loading at the observatory is dominated by the tides in the Atlantic Ocean. An additional contribution of local tidal loading in channels and groundwater is examined. The magnitude of the tidal loading is also reviewed in the context of the effects of solid earth tides, atmospheric loading and non-tidal loadsFacultad de Ciencias Naturales y Muse

Towards a tidal loading model for the Argentine-German Geodetic Observatory (La Plata)

Fil: Richter, Andreas. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Laboratorio MAGGIA; ArgentinaFil: Müller, Lisiane. Technische Universität Dresden. Institut für Planetare Geodäsie; GermanyFil: Marderwald, Eric rodolfo. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Laboratorio MAGGIA; ArgentinaFil: Mendoza, Luciano Pedro Oscar. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Laboratorio MAGGIA; ArgentinaFil: Kruse, Eduardo Emilio. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Perdomo, Santiago. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Scheinert, Mirko. Technische Universität Dresden. Institut für Planetare Geodäsie; GermanyFil: Perdomo, Raúl Aníbal. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin