Search results for "geofisica applicata"
showing 10 items of 169 documents
Archaeological excavation confirms the geophysical anomalies recorded at the cathedral of tarragona - A comparative study
2011
An integrated geophysical survey was conducted in September 2007 at the Cathedral of Tarragona to search for archaeological remains of the Roman temple dedicated to the Emperor Augustus. Many hypotheses about its location have been put forward, the most recent ones suggesting it could be inside the present cathedral. A project including Electrical resistivity tomography (ERT) and Ground probing radar (GPR) was planned for a year and conducted during a week of intensive field survey. Both ERT and GPR provided detailed information about subsoil structures. Different ERT techniques and arrays were used, ranging from standard Wenner-Schlumberger 2D sections to full 3D electrical imaging using t…
Contribution of HVSR measures for seismic microzonation studies
2018
The HVSR method applied to seismic noise can be a very useful technique to map the site effects of the territory, to identify the thickness of the soft covering and so the depth of the seismic bedrock. The case of the urban area of Oliveri is presented. Because of its high seismic hazard this area has been subject of first level seismic microzonation. The town lies on a large coastal plain made of mixed fluvial/marine sediments, overlapping a deformed substrate. In order to identify points on the area probably suffering of relevant site effects and to define a preliminary Vs subsurface model, 23 HVSR measurements were performed. A clustering technique of continuous signals has been used to …
Electrical resistivity and induced polarization tomographies to test the efficiency and safety of the new landfill of Bellolampo (Palermo, Italy)
2016
A geophysical study by means of electrical resistivity and induced polarization tomographies was carried out in the landfill site of Bellolampo (Palermo, Italy) to check the integrity of the landfill liner and to detect possible leachate plumes. Preliminarily, synthetic tests were performed, simulating acquisition data along profiles placed above resistivity distribution, suitable to represent landfills protected with an high-density polyethylene (HDPE) liner at the bottom or with possible leachate plumes. Optimized array data sets for parallel measurements have been tested in order to assess the resolution and the effectiveness of tomographic images, comparing inversions with and without t…
Contribution of the cluster analysis of HVSR data for near surface geological reconstruction
2015
The use of HVSR technique allows in many cases (Bonnefoy-Claudet et al. 2006) to obtain detailed reconstruction of the roof of the seismic bedrock (Di Stefano et al. 2014) and to identify areas with similar seismic behaviour. Theoretical considerations (Nakamura 1989) and experimental tests showed that amplification of horizontal motions between bottom and top of a sedimentary cover is well related to the ratio between the spectra of the horizontal and vertical components of the ground velocity (Nakamura 2000). This ratio is a measure of ellipticity of Rayleigh wave polarization, overlooking Love and body waves contribution. Assuming that subsoil can be represented as a stack of homogeneous…
Individuazione di cavità attraverso tomografie elettriche e sismiche
2020
Le tecniche geofisiche sono i metodi più efficienti per ottenere informazioni sulle strutture presenti nel sottosuolo. Ad oggi, la tomografia di resistività elettrica (ERT) è il metodo più utilizzato per il rilevamento di vuoti sotterranei, tuttavia, la combinazione con dati derivanti da diversi metodi geofisici è l’approccio più adatto per la determinazione delle cavità. Negli ultimi anni, la ERT è stata sempre più spesso congiunta alla tomografia sismica a rifrazione (SRT) al fine di ottenere interpretazioni più robuste anche utilizzando un approccio di tipo statistico. La cluster analysis eseguita su unità statistiche definite da valori di resistività elettrica, velocità delle onde P e d…
From Geophysics to Microgeophysics for Engineering and Cultural Heritage
2011
The methodologies of microgeophysics have been derived from the geophysical ones, for the sake of solving specific diagnostic and/or monitoring problems regarding civil engineering and cultural heritage studies. Generally, the investigations are carried out using different 2D and 3D tomographic approaches as well as different energy sources: sonic and ultrasonic waves, electromagnetic (inductive and impulsive) sources, electric potential fields, and infrared emission. Many efforts have been made to modify instruments and procedures in order to improve the resolution of the surveys as well as to significantly reduce the time of the measurements without any loss of information. This last poin…
Imaging Cultural Heritage at Different Scales: Part I, the Micro-Scale (Manufacts)
2023
Applications of non-invasive sensing techniques to investigate the internal structure and surface of precious and delicate objects represent a very important and consolidated research field in the scientific domain of cultural heritage knowledge and conservation. The present article is the first of three reviews focused on contact and non-contact imaging techniques applied to surveying cultural heritage at micro- (i.e., manufacts), meso- (sites) and macro-scales (landscapes). The capability to infer variations in geometrical and physical properties across the inspected surfaces or volumes is the unifying factor of these techniques, allowing scientists to discover new historical sites or to …
Electromagnetic and ultrasonic investigations on a Roman marble slab
2011
The archaeological museum of Rome asked our group about the physical consistency of a marble slab (second to third century AD) that recently fell during its travel as part of an exhibition. We decided to use different methodologies to investigate the slab: namely a pacometer (Protovale Elcometer) to individuate the internal coupling pins, and ground-penetrating radar (GPR) (2000 MHz) and ultrasonic (55 kHz) tomographic high-density surveys to investigate the internal extension of all the visible fractures and to search for the hidden ones. For the ultrasonic data, tests were carried out to optimize the inversion parameters, in particular the cell dimensions. Surely, the choice of cell size …
Integrated full 3D geoelectrical and GPR tomographies in the Ambulatory of the roman “Villa del Casale”(Piazza Armerina)
2008
The “Villa del Casale” is a wonderful Roman Villa excavated in the archaeological site of Piazza Armerina (Sicily) in 1929. Its interest is mainly to be referred to the floor mosaics, among the largest and most beautiful ones of Roman times, of superlative quality. The floor of the Corridor is covered by a wonderful mosaic depicting the hunt and capture of wild animals, so that it is called the “Corridor of the Great Hunting Scene”. The Villa is now under restoration, and during the planning of the restoration a 3D electrical resistivity tomography was performed on the corridor by using an acquisition grid composed by 704 electrodes. Furthermore 25 GPR profiles with 400 MHz antenna were acq…
Misinterpretation caused by 3D effects on 2D Electrical Resistivity Tomography: tests on simple models
2018
Summary The aim of this work is to evaluate the effects of 2D inversion of electrical resistivity data when in presence on 3D structures by testing synthetic and experimental models. Several numerical simulations have been calculated for different resistivity models and 2D datasets were extracted to study and quantify the effects of 2D inversion on 3D structures. Results have been compared with field texts carried out in quarrying sites. The main tests here presented simulates prism-shaped cavities with a square vertical section of 1 × 1 size and a variable lateral extension d, from 1 to infinity (this latter being a 2D tunnel model). Inversion of predicted data show that 2D tomography does…