Structural assessment of Mount Etna volcano from Permanent Scatterers analysis

A study of the deformation pattern of Mount Etna volcano based on the results from the Permanent Scatterers (PS) technique is reported. Ground motion data provided by the interferometric synthetic aperture radar (InSAR) PS technique from 1995 to 2000 are compared and validated by GPS data. An analysis of the ascending and descending line of sight (LOS) components of ground velocities has yielded detailed ground deformation maps and cross sections. This analysis allows detection and constraint of discontinuities in the surface velocity field. LOS velocities have then been combined to calculate the vertical and horizontal (E-W) ground velocities. A wide inflation of the edifice has been detected on the western and northern flanks (over an area of about 350 km(2)). A seaward motion of the eastern and southern flanks has also been measured. PS data allows the geometry and kinematics of the several blocks composing the unstable flanks to be defined even in the highly urbanized areas, and their displacement rates have been measured with millimeter precision. This analysis reveals the extension of some features beyond their field evidences and defines new important features. The results of this work depict a new comprehensive kinematic model of the volcano highlighting the gravitational reorganization of the unbuttressed volcanic pile on its slippery clay basement on the southern flank, but an additional drag force due to a strong subsidence of the continental margin facing the Etna volcano is necessary to explain the PS velocity field observed on the eastern flank.