Seismotectonic implications of the south chile ridge subduction beneath the patagonian andes

• Published in: Terra Nova
• Main Authors: Suárez, Rodrigo, Sue, Christian, Ghiglione, Matías, Guillaume, Benjamin, Ramos, Miguel, Martinod, Joseph, Barberón, Vanesa
• Other Authors: Instituto de Estudios Andinos “Don Pablo Groeber” (INDEAN), Consejo Nacional de Investigaciones Científicas y Técnicas Buenos Aires (CONICET)-Facultad de Ciencias Exactas y Naturales Buenos Aires (FCEyN), Universidad de Buenos Aires Buenos Aires (UBA)-Universidad de Buenos Aires Buenos Aires (UBA), Institut des Sciences de la Terre (ISTerre), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Argentinian-French ECOS-SUD A15U02
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; Antarc*; Antarctic
• Online Access: https://insu.hal.science/insu-03141233; https://insu.hal.science/insu-03141233/document; https://insu.hal.science/insu-03141233/file/ter.12521.pdf; https://doi.org/10.1111/ter.12521

International audience The South Chile ridge (SCR) intersects the Patagonian trench around 46° 09’S, forming the triple junction among the Antarctic, Nazca, and South America plates. Subduction of the SCR since ~18 Ma produced the opening of a slab window beneath Patagonia and a noticeable magmatic gap in the cordillera, profuse volcanism, and topographic uplift in the retroarc. To study seismicity distribution and present‐day stress resulting from this particular framework, we analyze databases of seismic events and earthquake focal mechanisms. Our study finds that clusters of intraplate crustal seismic events are disrupted by a ~450‐470 km seismicity gap above the slab window. Calculated stress tensors depict a strike‐slip tectonic regime north of the triple junction, and ~W‐E compression to the south of the seismic gap. We propose that the seismotectonic behavior of the upper plate is disturbed at the first order by the trench‐ridge intersection, leading to a heterogeneous stress field.