New insights into Mt. Vesuvius hydrothermal system and its dynamic based on a critical review of seismic tomography and geochemical features

摘要

The seismic velocity and attenuation tomography images, calculated invertingrespectively P-wave travel times and amplitude spectra of localVT quakes at Mt. Vesuvius have been reviewed and graphically representedusing a new software recently developed using Mathematica8TM.The 3-D plots of the interpolated velocity and attenuation fields obtainedthrough this software evidence low-velocity volumes associated with highattenuation anomalies in the depth range from about 1 km to 3 km belowthe sea level. The heterogeneity in the distribution of the velocity and attenuationvalues increases in the volume centred around the crater axisand laterally extended about 4 km, where the geochemical interpretationof the data from fumarole emissions reveals the presence of a hydrothermalsystem with temperatures as high as 400-450°C roughly in the samedepth range (1.5 km to 4 km). The zone where the hydrothermal systemis space-confined possibly hosted the residual magma erupted by Mt. Vesuviusduring the recent eruptions, and is the site where most of the seismicenergy release has occurred since the last 1944 eruption.