DInSAR deformation analysis of flank collapsing volcanoes: examples from Etna, Piton de La Fournaise and Fogo

Volcanoes may deform as a consequence of several processes. Among these, there are flank instability and collapse; these may be induced, in addition to magma emplacement, by fault activity and the pressurization of a hydrothermal system. Modern geodetic techniques, as spaceborne interferometric synthetic aperture radar (DInSAR), allow the detection of centimeter-to millimeter-scale deformation of a volcanic edifice and are invaluable tools for monitoring and understanding the relations between deformation and magmatic activity. Here we analyze the deformation of three volcanoes characterized by flank collapse through DInSAR technique: Etna, Piton de La Fournaise and Fogo. Etna was erupting every ~1.5 years over the last century. We show DInSAR results achieved in the last ~20 years by exploiting ERS, ENVISAT, ALOS and COSMO-SkyMed satellite data, focusing on the deformation of the eastern and western flanks of the volcano before, during, and after the major 2001 and 2002-2003 eruptions and on seismic swarm occurred in 2010 on Pernicana fault. Piton de la Fournaise present an eastern flank depression which is the scar of one of the most recent landslides. Recently, it has been extremely active, erupting 34 times between 1998 and 2011. We show deformation pattern by exploiting DInSAR Envisat and ALOS satellites from 2002 to 2010, focusing on 2007 eruption. Fogo volcano is the active expression of the Cape Verde mantle hot spot. A new eruption started in the morning of November 23th 2014 inside the summit caldera. It took place from a fissure with two closely spaced vents on the southwest side of the Pico de Fogo. We show the potential and capability of Sentinel-1 satellite to image the deformation pattern related to this eruption and model the deformation source.