Premium
Seismotectonic implications of the South Chile ridge subduction beneath the Patagonian Andes
Author(s) -
Suárez Rodrigo,
Sue Christian,
Ghiglione Matías,
Guillaume Benjamin,
Ramos Miguel,
Martinod Joseph,
Barberón Vanesa
Publication year - 2021
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/ter.12521
Subject(s) - geology , triple junction , subduction , seismology , induced seismicity , intraplate earthquake , trench , ridge , slab , slab window , stress field , compression (physics) , tectonics , paleontology , geophysics , oceanic crust , chemistry , physics , materials science , organic chemistry , layer (electronics) , finite element method , composite material , thermodynamics
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 analyse 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 behaviour of the upper plate is disturbed at the first order by the trench‐ridge intersection, leading to a heterogeneous stress field.