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The structural evolution of Andean-type orogens is strongly influenced by the geometry of the subducting slab. This study focuses on the flat-slab subduction of the Nazca Ridge and its effects on the South American Plate. The process of flat slab subduction impacts the stress distribution within the overriding plate and increases plate coupling and seismic energy release. Using the finite element method (FEM), we analyse interseismic and coseismic deformation along a 1000 km transect parallel to the ridge. We examine stress distribution, uplift patterns, and the impact of megathrust activity on deformation. To better define the crust's properties for the model, we developed a new thermal model of the Nazca Ridge subduction zone, reconstructing the thermal structure of the overriding plate. The results show concentrated stress at the upper part of the locked plate interface, extending into the Coastal and Western Cordilleras, with deeper stress zones correlating with seismicity. Uplift patterns align with long-term rates of 0.7–1 mm/yr. Cooling from flat-slab subduction strengthens the overriding plate, allowing far-field stress transmission and deformation. These findings provide insights into the tectonic processes driving stress accumulation, seismicity, and uplift along the Peruvian margin. [ABSTRACT FROM AUTHOR]

Understanding fault behavior in carbonates is critical because they represent loci of earthquake nucleation. Models of fault-slip mode generally assume: (1) seismic sliding and aseismic sliding occur in different fault patches, (2) creep is restricted to lithologycontrolled weak domains, and (3) rate-weakening patches are interseismically locked. We studied three carbonate-hosted seismogenic normal faults in central Italy by combining (micro)structural and geochemical analyses of fault rocks integrated with new seismic coupling estimates. The (upper bound) seismic coupling was estimated to be ∼0.75, which indicates that at least 25% of the longterm deformation in the study area is released aseismically in the upper crust. Microscopy and electron-backscatter diffraction analyses revealed that whereas the localized principal slip zone records seismic slip (as ultracataclastic material, calcite crystallographic preferred orientation (CPO), and truncated clasts), the bulk fault rock below behaves differently. Cataclasites in massive limestones deform by cataclastic flow, pressure solution, and crystal plasticity, along with CPO development. Foliated tectonites in micritic limestones deform by pressure solution and frictional sliding, with CPO development. We suggest these mechanisms accommodate on-fault interseismic creep. This is consistent with experimental results reporting velocitystrengthening behavior at low slip rates. We present multiscale evidence of coexisting seismic and aseismic slip along the same fault in limestones during the seismic cycle. Our results imply that on-fault aseismic motion must be added to seismic slip to reconcile the long-term deformation rates and that creep is not exclusive to phyllosilicate-bearing units. Our work constitutes a step forward in understanding fault behavior and the seismic cycle in carbonates, and it may profoundly impact future studies on seismogenic potential and earthquake hazard assessment. [ABSTRACT FROM AUTHOR]

In the last decades, multidiscipline investigation of the Apennine mountain belt of peninsular Italy has provided fundamental insights into the genesis and evolution of wedge-top basins. In this study, we focus on shallow-water to continental, Pliocene-Quaternary basins that formed on top of the southern Apennine allochthonous wedge after its emplacement onto a large foreland carbonate platform domain (Apulian Platform). The wedge-top basins analyzed in this study are mostly asymmetric, being bounded to the north by a normal fault showing evidence of synsedimentary activity. The basin successions are generally deformed by open folds and reverse faults resulting from shortening coeval with the sedimentation of the Lower Pliocene to lower--middle Pleistocene, upper part of the basin fill. Anisotropy of magnetic susceptibility data from the basin successions are consistent with a basin evolution characterized by an initial stage of tectonic subsidence controlled by roughly north-northwest--south-southeast-oriented extension, followed by southwest-northeast shortening active during subsequent basin filling. The latter shortening is marked by a dominant northwest-southeast mean trend of the magnetic lineation obtained from most sites in the study area and is interpreted as a result of upward propagation of deep-seated deformation (tectonic inversion) taking place within the buried Apulian Platform sitting in the footwall to the allochthonous wedge. Therefore, our results emphasize a complex interplay of different tectonic processes controlling wedge-top basin development. Au cours des dernieres decennies, une etude multidisciplinaire de la chaine de montagnes des Apennins dans la peninsule italienne a donne des apercus de la genese et de l'evolution des bassins sur le prisme d'accretion << wedge- top basins >>. Dans cette etude, nous ciblons les bassins d'eau peu profonde a continentaux, datant du Pliocene-Quaternaire, qui se sont formes sur le dessus du prisme allochtone du sud des Apennins, apres sa mise en place sur un vaste domaine de plateforme de carbonate d'avant-pays (la plate-forme apulienne). Les bassins sur le prisme d'accretion analyses dans la presente etude sont surtout asymetriques, puisqu'ils sont delimites au nord par une faille normale montrant des evidences d'activite syn-sedimentaire. Les successions de bassins sont generalement deformees par des plis ouverts et des failles inverses provenant d' un retrecissement contemporain de la sedimentation du Pliocene inferieur au Pleistocene inferieur moyen dans la partie superieure du remplissage du bassin. L'anisotropie des donnees de susceptibilite magnetique provenant des successions de bassin concorde avec une evolution du bassin caracterisee par un stade initial de subsidence tectonique controlee par une extension a orientation generale nord-nord-ouest-sud-sud-est, suivie d'un retrecissement sud-ouest-nord-est actif durant le remplissage subsequent du bassin. Ce dernier retrecissement montre une tendance moyenne dominante nord-ouest-sud-est de la lineation magnetique obtenue de la plupart des sites dans le secteur a l'etude et il est interprete comme le resultat d'une propagation vers le haut d'une deformation situee en profondeur (inversion tectonique) qui s'est produit dans la plate- forme apulienne enfouie se trouvant dans l'eponte inferieure du prisme allochtone. Nos resultats soulignent donc une interaction complexe entre les differents processus tectoniques qui controlent le developpement des bassins sur les prismes d'accretion. [Traduit par la Redaction], Introduction The Apennine belt of peninsular Italy represents a classic mountain chain--foredeep system for which the transition from passive margin to foreland basin sedimentation has been thoroughly documented (e.g., Ricci-Lucchi [...]