Chile Atacama 1922 Seismic Gap Gnss Interplate Locking Locking Degree Seismic Catalog

External authors:

• Diego Gonzalez-Vidal ( Universidad de Concepcion )
• Christian Sippl ( Institute of Geophysics of the Czech Academy of Sciences )
• J. C. Baez ( Universidad de Chile )
• Francisco Ortega-Culaciati ( Universidad de Chile )
• Dietrich Lange ( GEOMAR Helmholtz Center for Ocean Research Kiel )
• Frederik Tilmann ( Helmholtz-Center Potsdam GFZ German Research Center for Geosciences , Free University of Berlin )
• Anne Socquet ( Universite Savoie Mont Blanc )
• Jan Bolte ( University of Kiel )
• Joaquin Hormazabal ( Universidad de Chile )
• Mickael Langlais ( Universite Savoie Mont Blanc )
• Catalina Morales-Yanez ( Universidad Catolica de la Santisima Concepcion )
• Daniel Melnick ( Universidad de Concepcion )
• Roberto Benavente ( Universidad Catolica de la Santisima Concepcion , Natl Res Ctr Integrated Nat Disaster Management CI )
• Jannes Muenchmeyer ( Universite Savoie Mont Blanc )
• Rodolfo Araya ( Universidad de Concepcion )
• Benjamin Heit ( Helmholtz-Center Potsdam GFZ German Research Center for Geosciences )

Abstract:

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 utilize a transdimensional Bayesian inversion to estimate interplate locking. 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 with lower locking (27.5 & DEG;S-27.7 & DEG;S) coincides with higher seismicity levels, a high number of repeating earthquakes and events extending toward the trench. This area is situated where the Copiapo Ridge is subducted and has shown previous indications of both seismic and aseismic slip, including an earthquake sequence in 2020. 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.