Resumen
GPS data from stations around the Chaitén Volcano show a co-eruptive pattern of inflation and deflation that correlates well with the estimated effusion rate during the 2008-2009 eruption. Axisymmetric radial deflation is coeval with periods of fast dome growth and inflation is coeval with periods of mostly endogenous dome growth at lower rates. Non-volcanic basement appears to be involved in the ground deformation as was inferred previously from InSAR observations. Data are insufficient to conduct full source modeling, but simple models are compatible with those that are based on petrological and geophysical observations. Modeling results based on GPS measurements suggest a strong coupling between the eruptive dynamics and response of the surrounding basement, which was probably conditioned by its structural fabric and crustal tectonics.