Journal ArticleStress transmission along mid-crustal faults highlighted by the 2021 Mw 6.5 San Juan (Argentina) earthquakeAmmirati, Jean-Baptiste; Mackaman-Lofland, Chelsea; Zeckra, Martin; Gobron, Kevin<title>Abstract</title> <p>Understanding the mechanisms of crustal deformation along convergent margins is critical to identifying seismogenic structures and assessing earthquake hazards for nearby urban centers. In the southern central Andes (28–33<inline-formula><alternatives><tex-math>$$^{\circ }$$</tex-math><math><msup><mrow/><mo>∘</mo></msup></math></alternatives></inline-formula>S), differences in the style of middle to upper-crustal deformation and associated seismicity are highlighted by the January 19th, 2021 (Mw 6.5) San Juan earthquake. We integrate waveforms recorded at regional and teleseismic distances with co-seismic displacements calculated from local Global Navigation Satellite System time series, to re-estimate the source parameters of the 2021 San Juan earthquake, confirming a mid-crustal nucleation depth (21 ± 2 km) and right-lateral transpressional mechanism. Considered alongside decades of seismic observations and geological data, this event provides evidence for retroarc deformation partitioning among inherited basement faults and upper-crustal structures in response to oblique convergence of the Nazca and South American plates. As they may transfer shortening to active upper-crustal faults associated with historically devastating shallower earthquakes, a better understanding of seismogenic basement faults such as the mid-crustal structure activated during the 2021 San Juan earthquake earthquake could help future re-assessment of the seismic risk in western Argentina.</p>Scientific Reports2022-12-0110482563Scientific Reports1212045-2322https://doi.org/10.1038/s41598-022-22752-61952791National Science Foundation