San Juan Province lies in an area where the South American Plate is affected by flat-slab subduction of the underlying Nazca Plate, the so-called Pampean flat-slab. The very shallow angle leads to a much greater degree of coupling between the subducting and overriding plates.
The San Juan Province is situated within an area characterized by flat-slab subduction of the Nazca Plate beneath the South American Plate, leading to a high degree of interaction and coupling between the two plates.