Stress transfer in the Lazufre volcanic area, central Andes

We generated a 13-year InSAR time series from 1995 -2008 to investigate the spatiotemporal characteristics of two neighboring volcano's deformations for the Lazufre volcanic area, central Andes. The data reveal two scales of uplift initiating during the observation time: (1) a large-scale uplift started in 1997 that shows an increase of the mean uplift rate of up to 3.2 cm/yr, now affecting several eruptive centers situated in an area larger than 1800 km 2 and (2) a small-scale uplift located at Lastarria volcano, which is the only volcano to show strong fumarolic activity in decades, with most of the clear deformation apparently not observed before 2000. Both the large and small uplift signals can be explained by magmatic or hydrothermal sources located at about 13 km and 1 km deep, respectively. To test a possible relationship, we use numerical modeling and estimate that the depth inflating source increased the tensile stress close to the shallow source. We discuss how the deep inflating source may have disturbed the shallow one and triggered the observed deformation at Lastarria.