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The Southern Patagonian Icefield (SPI) lies above an area of slow convergence between Antarctic and South-America plates, where limited seismicity is recorded by global and regional seismic networks. To understand the seismic behavior of this zone, we analyze two years of continuous broad-band data recorded by 27 seismometers, deployed around the SPI. Substantial ice loss coupled with the unusually low viscosity of the underlying mantle is causing a rapid uplift. Our findings indicate that most of the seismicity occurs in the upper crust , likely associated with the (re)activation of regional compressive structures. However, earthquakes immediately beneath the SPI generally are shallower and show normal or strike-slip faulting. We suggest that this activity is promoted as a response to the crustal relaxation after rapid ice removal of SPI. The almost complete absence of interplate and intraslab events is consistent with a locked megathrust fault interface, highlighting the similarity of this region with the Cascadia subduction zone. • Shallow seismicity is observed in the majority in the area of southern Patagonia Icefield. • The inferred stress suggests the solid earth response to mass loss from the icefield as the major cause. • The almost complete absence of interplate earthquakes suggests that the megathrust may be locked. [ABSTRACT FROM AUTHOR]

In the South‐Central Andes, the crustal structures driving the tectonic evolution of the Andean Cordillera remain unresolved. So far, most seismological studies focused on the subduction interface, leaving crustal seismicity and its relationship with crustal deformation and Andean volcanism mostly unconstrained. However, because of their large number compared to higher magnitude events, the characterization of small‐magnitude crustal earthquakes is key to identify active structures and better constrain the tectonic models. In this work, we exploit 53 months of continuously recorded, three‐component waveforms from the permanent seismic network in central Chile using a deep‐learning approach to improve the detection of small‐magnitude earthquakes. To increase station coverage, we also use the seismic phases obtained from a previous temporary seismic deployment. We use the obtained seismicity catalog to refine tomographic models of that region, revealing a more detailed architecture of the Chilean forearc. Travel times calculated in the new 3‐D velocity model allowed us to locate ∼14,000 earthquakes. Refined double‐difference relocations of ∼4,900 events located beneath the West Andean Thrust suggest a large‐scale, west‐dipping structure which, together with the west‐verging tectonic front, likely contributed to the uplift and crustal deformation during the past ∼20 Myr. Plain Language Summary: The occurrence of earthquakes is closely related to plate tectonics and in particular, the creation of mountain ranges and their evolution over very long periods of time. In order to better understand how these processes work in the Andes of Central Chile, we analyze more than 4 years of earthquake records using a machine learning algorithm. This technique allows us to automatically and reliably detect very small earthquakes, that are, in general, missing in the seismicity catalogs. Since they are also more numerous, we can use them to improve the geophysical images and reveal more details of crustal structures. We find that most of the superficial earthquakes beneath the Andean Cordillera are aligned with a major structure, dipping toward the west. This structure accommodates processes of shortening and uplifting directly related to the construction of the Andes. Key Points: A large number of earthquakes detected using a deep‐learning approach are used for local earthquake tomographyThe obtained 3‐D seismic wave velocity structure is used to relocate the seismicity catalogEarthquake locations suggest a west‐dipping major structure that we interpret to have contributed to the uplift of the South‐Central Andes [ABSTRACT FROM AUTHOR]