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Relation between oceanic plate structure, patterns of interplate locking and microseismicity in the 1922 Atacama Seismic Gap
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  • Diego González-Vidal,
  • Marcos Moreno,
  • Christian Sippl,
  • Juan Carlos Baez,
  • Francisco H. Ortega-Culaciati,
  • Dietrich Lange,
  • Frederik Tilmann,
  • Anne Socquet,
  • Jan Bolte,
  • Joaquin Hormazabal,
  • Mickaël Langlais,
  • Catalina Morales-Yáñez,
  • Daniel Melnick,
  • Roberto Benavente,
  • Rodolfo Araya
Diego González-Vidal
University of Concepción
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Marcos Moreno
Pontifical Catholic University of Chile

Corresponding Author:marcos.moreno@ing.puc.cl

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Christian Sippl
Institute of Geophysics, Czech Academy of Sciences
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Juan Carlos Baez
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Francisco H. Ortega-Culaciati
Universidad de Chile
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Dietrich Lange
Geomar, Helmholtz-Zentrum für Ozeanforschung Kiel
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Frederik Tilmann
Deutsches GeoForschungsZentrum GFZ
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Anne Socquet
Université Grenoble Alpes
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Jan Bolte
Kiel University
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Joaquin Hormazabal
University of Chile
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Mickaël Langlais
Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre
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Catalina Morales-Yáñez
Universidad Católica de la Santísima Concepción
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Daniel Melnick
Universidad Austral de Chile
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Roberto Benavente
Universidad Catolica de la Santissima Concepcion
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Rodolfo Araya
University of Concepción
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We deployed a dense geodetic and seismological network in the Atacama seismic gap in Chile. We derive a microseismicity catalog of >30,000 events, time series from 70 GNSS stations, and apply a transdimensional Bayesian inversion to estimate interplate locking degree. We identify two highly locked regions of different sizes whose geometries appear to control seismicity patterns. Interface seismicity concentrates beneath the coastline just downdip of the highest locking. A region of lower interplate locking around 27.5ºS coincides with higher seismicity levels, a high number of repeating earthquakes and events extending further towards the trench. Having shown numerous signs of aseismic deformation (slow-slip events and earthquake swarms), this area is situated where the Copiapó Ridge is subducted. While these findings suggest that the structure of the downgoing oceanic plate prescribes patterns of interplate locking and seismicity, we note that the Taltal Ridge further north lacks a similar signature.
15 Mar 2023Submitted to ESS Open Archive
16 Mar 2023Published in ESS Open Archive