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

Rodrigo Suárez (1) , Christian Sue (2) , Matías Ghiglione (1) , Benjamin Guillaume (3) , Miguel Ramos (1) , Joseph Martinod (2) , Vanesa Barberón (1)

1 INDEAN - Instituto de Estudios Andinos “Don Pablo Groeber”
2 ISTerre - Institut des Sciences de la Terre
3 GR - Géosciences Rennes

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.

Domains: Tectonics

Rodrigo Suárez, Christian Sue, Matías Ghiglione, Benjamin Guillaume, Miguel Ramos, et al.. Seismotectonic implications of the south chile ridge subduction beneath the patagonian andes. Terra Nova, 2021, 33 (4), pp.364-374. ⟨10.1111/ter.12521⟩. ⟨insu-03141233⟩