Interplay of seismic and a-seismic deformation during the 2020 sequence of Atacama, Chile

An earthquake sequence occurred in the Atacama region of Chile throughout September 2020. The initiated by a mainshock magnitude Mw= 6.9, followed 17 hours later 6.4 aftershock. lasted several weeks, during which more than thousand events larger Ml= 1 occurred, including earthquakes magnitudes between 5.5 and 6.4. Using dense network that includes broad-band, strong motion GPS sites, we study details seismic sources its largest aftershock, afterslip they generate their shedding light spatial temporal evolution aseismic slip sequence. Dynamic inversions show two are located on subduction interface have stress drop rupture times characteristics earthquakes. aftershocks, localized 3D velocity model, occur narrow interseismic coupling (ranging 40%-80%), i.e. large highly coupled areas, North South sequence, both ruptured great Mw∼8.5 1922 megathrust earthquake. High rate data (1 Hz) allow to determine instantaneous coseismic displacements infer models, not contaminated early afterslip. We find total over 24 inferred from precise daily solutions is sum models. Differencing models indicates rapid developed up-dip area down-dip During separating earthquakes, micro-seismicity migrated towards epicenter Mw aftershocks continued propagate upwards at ∼ 0.7 km/day. bulk accompanied with migration seismicity, aftershock area, suggesting this triggered Unusually post-seismic slip, equivalent 6.8 three weeks North, low areas downdip strip higher coupling, possibly connecting deep Slow Slip Event detected Copiapo 2014. highlights how interacted witness short scale lateral variations friction properties megathrust.