Interseismic Loading of Subduction Megathrust Drives Long-Term Uplift in Northern Chile

Large earthquakes are the product of elastic stress that has accumulated over decades to centuries along segments of active faults. Assuming an elastic crust, one can roughly estimate the location and rate of accumulation of elastic stress. However, this general framework does not account for inelastic, irrecoverable deformation, which results in large-scale topography. We do not know over which part of the earthquake cycle such deformation occurs. Using InSAR and GNSS measurements, we report on a potential correlation between long-term, inelastic vertical rate and short-term, interseismic vertical rate in northern Chile. Approximately 4% to 8% of the geodetically derived interseismic vertical rates translate into permanent deformation, suggesting that topography of the forearc builds up during the interseismic period. This observation provides a quantitative basis for an improved understanding of the interplay between short-term and long-term dynamics along convergent plate boundaries.