SEISMIC TOMOGRAPHY ON THE GROUND
Instrumentation for geognostic investigation
This survey method is used to identify physical-geometrical anomalies of the sub-soil with a definitely higher resolution compared to the other seismic prospecting methods; it gives the opportunity to create an image of the object investigated, where all the anomalies present will be reproduced (also the most particular ones, which could not be solved through any other method). In particular, the tomographic method allows to reproduce the geometric distribution of the elements that constitute a specific section, starting from the analysis of the behavior of the radiations that cross it.
The tomography is a general technique that allows to reproduce two-dimensional or three-dimensional objects through a defined number of one-dimensional and variously oriented projections of those objects. The seismic tomography reproduces an image of the internal structure of the ground by measuring the crossing time (or amplitudes) of seismic waves which propagate through a specific section.
The purpose is to determine a detailed distribution progress of such physical properties as the speed or extenuation of the seismic waves. A numerical simulation of the propagating phenomenon will identify the unknown fields of seismic waves velocity and will allow, in that way, to calculate more accurately their crossing times and, consequently, to make an effective discretization of the structure, which can be then transformed into the two-or-three-dimensional image.