The combination of geophysical data and geotechnical measurements may greatly improve the quality of buildings under construction in civil engineering. A case study is presented here at a vacant building site. Initially, boreholes indicated a complex geology. A dipole-dipole configuration was selected for electrical resistivity tomography (ERT) implementation and the data were processed and interpreted by applying 2D and 3D inversions. An electromagnetic survey was also carried out at a different time periods and successfully used to verify the results of the resistivity measurements. It is demonstrated that engineering geophysics is able to provide solutions for determining subsurface properties and that different prospection techniques are necessary for developing a reasonable model of the subsurface structure.

[1] The three-dimensional (3-D) electron density representation of the ionosphere computed by the assimilative IRI-SIRMUP-P (ISP) model was tested using IONORT (IONOspheric Ray-Tracing), a software tool for calculating a 3-D ray-tracing for highfrequency waves in the ionospheric medium. A radio link was established between Rome (41.8 N, 12.5 E) in Italy, and Chania (35.7 N, 24.0 E) in Greece, within the ISP validity area, and for which oblique soundings are conducted. The ionospheric reference stations, from which the autoscaled foF2 and M(3000)F2 data and real-time vertical electron density profiles were assimilated by the ISP model, were Rome (41.8 N, 12.5 E) and Gibilmanna (37.9 N, 14.0 E) in Italy, and Athens (38.0 N, 23.5 E) in Greece. IONORT was used, in conjunction with the ISP and the International Reference Ionosphere 3-D electron density grids, to synthesize oblique ionograms. The comparison between synthesized and measured oblique ionograms, both in terms of the ionogram shape and the maximum usable frequency characterizing the radio path, demonstrates both that the ISP model can more accurately represent real conditions in the ionosphere than the IRI, and that the raytracing results computed by IONORT are reasonably reliable.

The present paper cannot be considered, either as a rebuttal to any participant, or our overview of the debate. Its publication became necessary due to the fact that various participants raised additional questions, i.e., beyond the points suggested by Varotsos et al. [1996]. We clarify these questions that concern the noise discrimination from our electrical recordings, the recent laboratory experiments which support the emission of electrical precursors, and the question on whether, or not, a retroactive adjustment of the VAN prediction parameters was made, after the period 1987–1989 discussed in this debate. We draw attention to the fact that a continuous 9 year (i.e., 1987–1995) sample of VAN predictions is now available. For the benefit of the reader, the present paper also summarizes the essence of the five Principles suggested by Varotsos et al. [1996] (as a consequence, attention is drawn to a correct definition of the success rate). This essence remains exactly the same as it was initially suggested, because we do not feel, after the debate, that the various contributions cast a sound doubt on the correctness of any of these Principles. The calculations which claim that VAN predictions can be ascribed to chance strongly violate these Principles; the incorrectness of these calculations is beyond any doubt, because they “reject” even an ideal earthquake prediction method. On the other hand, several well founded calculations convince that the VAN's success (and alarm) rate is very far beyond chance. The study of this paper is highly recommended to the reader before going through the details of each of our individual Replies.

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