Array analysis of seismograms from explosive sources: Evidence for surfacewaves scattered at the main topographical features

In this article, we analyze the seismic wavefield produced by blasts fired at Mt. Vesuvius for a deep seismic sounding experiment and recorded by a de nse short-period three-component seismic array. Seismograms from five explo sions occurring at the bottom of wells located at different distances and a zimuth with respect to the array site have been analyzed with the zero lag cross-correlation technique applied to both vertical and horizontal compone nts in the frequency range 3-7 Hz. The aim is to analyze the portion of the seismograms long after the first P onset in order to obtain the slowness a nd backazimuth distribution of correlated secondary phases. Polarization an alysis in time domain, carried out using the array covariance matrix techni que, has also been applied to the well-correlated phases to determine their wave composition. Results show that the con-elated phases detected in the coda of the seismogram shots are composed almost entirely of surface waves. Location of the scatterers shows a high concentration of the scatterers in and around the volcanic edifice of Mt. Vesuvius, confirming that topograph ical irregularities play an important role in the generation of the high-fr equency scattering phenomena.