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A long-lived swarm on the Central Bransfield Basin, Antarctica
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  • Piero Poli,
  • Leoncio Cabrera,
  • Maria Costanza Flores,
  • Jean Baptiste Ammirati,
  • Joaquin Vásquez,
  • Sergio Ruiz
Piero Poli
Université Grenoble-Alpes, Isterre Laboratory, CNRS

Corresponding Author:pieropoli85@gmail.com

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Leoncio Cabrera
ISTerre Institut des Sciences de la Terre, CNRS, Université Grenoble Alpes
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Maria Costanza Flores
Centro Sismológico Nacional, Universidad de Chile, Chile
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Universidad de Chile
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Jean Baptiste Ammirati
Department of Geology, Faculty of Physics and Mathematics, Universidad de Chile, Chile.
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Joaquin Vásquez
Universidad de Talca, Maule, Chile
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Sergio Ruiz
Universidad de Chile
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We study a large and long-lived earthquakes swarm occurring in 2020-2021 in the Bransfield Basin, south of the South Shetland islands, Antarctica. We make use of local seismological stations to detect and characterize more than 36000 small earthquakes, occurring from the end of August 2020 to June 2021. Together with the occurrence of the ~36000 earthquakes, we observe a significant (up to 8cm) geodetic deformation at nearby GPS stations. By joint interpretation of b-value, spatiotemporal evolution of seismicity and geodetic deformation, we infer a volcanic origin for this swarm, which takes place close to the ridge axis. Our study suggest that a significant amount of extension observed at the Bransfield Basin ridge is occurring in rapid deformation episodes (e.g., 1 year), and is most likely driven by volcanic activity localized at the ridge axial volcanic structure, rather than at the rifting bounding border faults.