Location of cavities buried in the Neapolitan Yellow Tuff using the seismic reflection method

A shallow seismic reflection survey was carried out at two sites near the city of Naples, where a large number of cavities have been dug over the past centuries into the Yellow Tuff Formation. To predict the response of the ground-cavity system to the seismic pulse, 2D synthetic wave propagation seismograms were produced using forward modelling theory. Then the seismic data were processed in two different ways to search for the diffraction hyperbolae generated by the cavity, and for any breaks in seismic reflectors below the area where the cavity is located. At the first site (Frattaminore), we were able to detect the diffraction hyperbolae, and with them to calculate the depth of the cavity. Here, we could also record the reflection from the top of the volcanic tuff, but, because of the complex environment and of the data quality, deeper reflections were not well visible on the seismogram. Thus, in order to improve the temporal resolution of the records and their signal-to-noise ratio, the data were processed by deconvolution and F-K dip-filtering. After this other, deeper events appeared on the section, but not in the depth range of the cavity. Despite the similar geological conditions of the two sites, it was not possible to record good seismic data at Grumo Nevano, due to the different environ,mental noise.