Location of cavities with geophysical methods: An example of combination of seismic reflection and dipole geoelectrics in the Phlegrean Fields (Southern Italy)

Abstract

A shallow seismic reflection and a dipole geoelectric surveys were carried out at one site located in the Phlegrean Fields, a volcanic area near Naples (Italy). The target is constituted by a railway tunnel excavated in the Neapolitan Yellow Tuff', a compact volcanic formation very common in the area. The test has an important practical application, in terms of reduction of the risk associated with the presence of many unknown cavities, dug in the past centuries into the tuff formation to extract material for building. In order to predict the seismic and electric response of the ground-cavity system, 2D syn-thetic wave propagation seismograms and 2D models of the electric response of the ground were produced.