We use continuous and survey GNSS data to image the spatial and temporal evolution of afterslip during the two-months following the Mw8.3 Illapel earthquake. Our approach solves for the incremental daily slip on the subduction interface using non-negative least-squares and spatial/temporal minimum Laplacian constraints. We find that afterslip developed at three specific areas at the megathrust, surrounding the coseismic rupture. The largest patch takes place at shallow depth north of the coseismic rupture. Smaller patches occur at greater depth north and south of the rupture, but no afterslip is found downdip. In addition, well resolved afterslip also occurs within the coseismic area that experienced 3-5 meters of seismic slip. Our afterslip model shows striking correlations with the spatial distribution of aftershocks and repeating earthquakes. A Mw6.8 aftershock occur on November 7 at the deep patch of enhanced afterslip and our inversion captures the triggered afterslip. Two Mw6.9 events occurred 100 km north of the rupture 55 days after the mainshock. The enhanced shallow afterslip developing northward possibly triggered these remote and delayed events. Enhanced afterslip spatially correlates with areas having experienced regular seismic swarms observed during the years prior to the Illapel earthquake. This correlation supports the view of localized fluid high-pore pressure areas behaving aseismically and surrounding a highly locked asperity, preventing the seismic rupture to propagate into them. The similarity with the behavior observed for the Mw7.8 2016 Ecuador and Mw7.6 2012 Costa Rica, suggests a common behaviour for heterogeneous subduction interfaces.

We study a large and long-lived earthquakes swarm occurring in 2020-2021 in the Bransfield Basin, south of the South Shetland islands, Antarctica. We make use of local seismological stations to detect and characterize more than 36000 small earthquakes, occurring from the end of August 2020 to June 2021. Together with the occurrence of the ~36000 earthquakes, we observe a significant (up to 8cm) geodetic deformation at nearby GPS stations. By joint interpretation of b-value, spatiotemporal evolution of seismicity and geodetic deformation, we infer a volcanic origin for this swarm, which takes place close to the ridge axis. Our study suggest that a significant amount of extension observed at the Bransfield Basin ridge is occurring in rapid deformation episodes (e.g., 1 year), and is most likely driven by volcanic activity localized at the ridge axial volcanic structure, rather than at the rifting bounding border faults.