We used SAR interferometry and GPS to measure the rise of an anticline beneath the urban area of Catania (Italy), which originates from outward thrusting above the basal decollement of Etna volcano. The anticline grows at a rate of over 0.015 m a-1 of SE thrusting and about 0.007 m a-1 of relative uplift. By relating this growth to the simultaneous extension measured at the summit of the volcano, we demonstrate the occurrence of active volcanic spreading. This process may exert a control on eruptions, earthquakes, sector collapses, and landslides ¿ 2000 American Geophysical Union