Maria Sileo

Ultrasonic pulse velocity for the evaluation of physical and mechanical properties of a highly porous building limestone

UPV as non-destructive technique can effectively contribute to the low invasive in situ analysis and diagnosis of masonry elements related to the conservation, rehabilitation and strengthening of the built heritage. The use of non-destructive and non-invasive techniques brings all the times many advantages in diagnostic activities on pre-existing buildings in terms of sustainability; moreover, it is a strong necessity with respect to the conservation constraints when dealing with the historical-architectural heritage. In this work laboratory experiments were carried out to investigate the effectiveness of ultrasonic pulse velocity (UPV) in evaluating physical and mechanical properties of Lecce stone, a soft and porous building limestone. UPV and selected physical-mechanical parameters such as density and uniaxial compressive strength (UCS) were determined. Factors such as anisotropy and water presence that induce variations on the ultrasonic velocity were also assessed. Correlations between the analysed parameters are presented and discussed. The presence of water greatly affected the values of the analysed parameters, leading to a decrease of UPV and to a strong reduction of the compressive strength. A discussion of the role of the water on these results is provided. Regression analysis showed a reliable linear correlation between UPV and compressive strength, which allows a reasonable estimation of the strength of Lecce stone by means of non-destructive testing methods such as the ultrasonic wave velocity. Low correlation between UPV and density was found, suggesting that other factors than density, related to the fabric and composition, also influence the response of the selected stone to the UPV. They have no influence on the UCS, that instead showed to be highly correlated with the packing density.

Archeological crop marks identified from Cosmo-SkyMed time series: the case of Han-Wei capital city, Luoyang, China

ABSTRACT The development of spaceborne Synthetic Aperture Radar (SAR) technology declares that the golden era of SAR remote sensing in archeology is approaching; however, nowadays its methodology framework is still lacking due to the inadequate case studies validated by ground-truths. In this study, we investigated the crop marks using multi-temporal Cosmo-SkyMed data acquired in 2013 by applying a two-step decision-tree classifier in conjunction with a spatial analysis in an area of archeological interest nearby the archeological site of Han-Wei capital city (1900–1500 BP), in Luoyang, China. The time-series backscattering anomalies related to the wheat growth cycle were identified and then further validated in two zones by geophysical investigations (Ground Penetration Radar and electrical measurements) and in a third zone by archeological excavations made after the SAR data acquisition. This study provides a new approach for the relic detection, shallowly buried and covered by the crop vegetation, by temporal crop marks on spaceborne SAR images. We also emphasize the necessity to establish a satellite-to-ground methodology framework for the promotion of remote-sensing technology in archeology.

Integrated prospecting in the crypt of the Basilica of Saint Nicholas in Bari, Italy

In this paper, we present the results of non-destructive integrated geophysical surveys (ground penetrating radar (GPR) and seismic sonic) performed in the crypt of the Basilica of St Nicholas in Bari, Italy. The aim was twofold, namely to investigate the consistency of restoration work performed in 1950 and the presence of features of archaeological interest. The GPR technique has also been exploited to characterize the subsurface water content under the crypt. In particular, the existence of buried anomalies, probably due to the restoration work, has been identified. Moreover, by means of an electromagnetic-wave velocity analysis, an estimation of the volumetric water content under the floor has been achieved. The results indicate the main causes of the deterioration and have provided significant information for the safeguard of this historical building. Furthermore, the GPR survey allowed us to identify some anomalies buried under the crypt that are probably of archaeological interest. Finally, both sonic tomography and a GPR survey have been performed on an important mosaic, and have enabled us to identify probable ?internal? reasons for its decay.

Remote Sensing and Geophysics for the Study of the Human Past in the Nasca Drainage

This chapters presents and discusses the results of investigations performed by ITACA Mission of CNR in the Nasca drainage basin, including the ceremonial center of Cahuachi, from 2007 to 2014. The employed approach was based on the multiscale and multisensor integration of remote-sensing methods, including geophysics . Most of the applications have been intended for preventive archaeology, in particular, for providing information on the presence of buried sites and structures by identifying different surface characteristics such as arid bare ground in the Pampas and vegetated areas in the river oases. The operational use of earth-observation technologies has been the occasion to develop ad hoc approaches to data acquisition, processing, and interpretation for the detection of earthen buried structures that is a crucial and challenging issue due to the subtle physical contrast between earthen remains and the surrounding subsoil. This made necessary amassing experience in, and the testing of, various techniques to investigate the subsoil by geophysical and remote methods, working side by side with archaeologists, involved in the interpretation of the results. The obtained results have been the discovery of previously unknown sites in the Nasca drainage basin, the identification of buried ritual offering, the characterization of the stepped structure of Templo Sur, and the mapping of areas of archaeological interest.

Geophysical Methods and Spatial Information for the Analysis of Decaying Frescoes

A promising application field of geophysics is monitoring and analysis of the state of conservation of works of art, such as wall paintings including frescoes. To this aim, two are the issues to address: the choice of the most appropriate survey instrument and method, and the analysis and interpretation of data coming from the survey, after their processing. This paper deals with a spatial analysis based protocol for the interpretation of data coming from different non-invasive tests, to improve the extraction process of the pattern decay. The case study is a frescoed wall of Gymnasium in Pompeii, investigated with the following non-invasive techniques: structure-from-motion photogrammetry (SfM), ground-penetrating radar, multitemporal infrared thermography.

Integrated In Situ Investigations for the Restoration: The Case of Regio VIII in Pompeii

This chapter presents the study case of the integration of noninvasive in situ investigation methods able to provide information useful to survey and characterize the state of decay of some masonry walls and frescoes in two blocks (insulae) of the Regio VIII in Pompeii. The integrated investigations demonstrated the complementarity of ground-penetrating radar (GPR), seismic tomography, and infrared thermography (IRT) for the diagnosis of the state of conservation and the restoration of structures and surfaces of archaeological monuments. The investigation was very useful in planning the restoration work.

Reconstructions, Transfers and Forced Abandonments Brought About by Earthquakes and Landslides in the Historical Centres of Southern Italy: The Role of Primary Sources

Italy is among the most prone Mediterranean countries to extreme natural menaces, such as earthquakes and landslides. These can cause serious damage to the properties and consequent changes in urban areas and historical centres especially, due to their high vulnerability. Starting from these preliminary remarks the paper deals with an ongoing research activity aimed at analyzing in depth and in a systematic way the damage and the consequent abandonments, transfers, and forced reconstructions caused by significant earthquakes and/or landslides in the historical centres of Southern Italy during the twentieth century. To make clear the methodology followed, the paper analyses three case studies related to the same number of historical centres menaced by mass movements and/or earthquake phenomena. The final aim of the research is to setup a reference Web Gis Atlas that will be a further tool that the stakeholders will find useful to improve mitigation risk actions against the two main geological menaces acting in Italy.

Non-destructive and laboratory diagnostic study on the mosaic of the crypt of St. Nicholas (Bari, Italy)

The crypt of St. Nicholas in Bari, Southern Italy, is a building of cultural worldwide importance. Inside the crypt a mosaic develops on the apsidal floor and along a parietal seat placed along the apsidal masonry, in the form of cladding. A surviving portion of the mosaic pavement is also preserved in the right lateral chapel. Integrated non-destructive survey and laboratory analyses were undertaken for the diagnostic study of the mosaic. GPR prospection was successfully applied to the study of its conservation state, that is strictly related to the condition of the subsoil, in particular to the presence and distribution of water. The presence of water, whose rise interests also some portions of the masonry and water content distribution were identified by the results of electromagnetic wave velocity analysis in GPR data. The decay visible on the tesserae evidenced widespread spalling and crumbling as typical forms that selectively affect the different materials of the tesserae of the mosaic. Samples taken from them were investigated by optical microscopy, X-ray diffraction, ion chromatography, infrared spectroscopy and thermogravimetric analyses, in order to identify the constituent materials and the products of their decay. The application of the integrated methodologies showed its effectiveness in order to acquire a quite complete knowledge for diagnostic purpose. Decay appeared to be due to the combined presence of water and soluble salts and it has different effects depending on the materials characteristics.

Multi-frequency Electromagnetic Induction Survey for Archaeological Prospection: Approach and Results in Han Hangu Pass and Xishan Yang in China

This study presents the potential of multi-frequency electromagnetic induction (EMI) in archaeology. EMI is currently less employed for archaeological prospection with respect to other geophysical techniques. It is capable of identifying shallow subsurface relics by simultaneously measuring the apparent electrical conductivity (ECa) and apparent magnetic susceptibility (MSa). Moreover, frequency sounding is able to quantify the depths and vertical shapes of buried structures. In this study, EMI surveys with five frequencies were performed at two heritage sites with different geological conditions: Han Hangu Pass characterized by cinnamon soil and Xishan Yang by sandy loams. In the first site, high ECa values were observed with variations in depth correlated to archaeological remains. Moreover, electromagnetic anomalies related to an ancient road and five kiln caves were identified. In the second site, an ancient tomb, indicating extremely low ECa and high MSa, was discovered. Its electromagnetic properties are attributed to the cavity and ferroferric oxides.

Archaeogeophysical-Based Approach for Inca Archaeology: Overview and one operational application

Even if, in recent decades, the use of remote sensing technologies (from satellite, aerial and ground) for archaeology is stepping into its golden age, in Southern America geophysics for preventive archaeology is more recent and less used than in Europe, Central America and Middle East. In this paper, we provide a brief overview and show the preliminary results obtained from the investigations conducted in Chachabamba (Peru). The archaeological area is located on a strategic terrace overlooking three Inca roads, which served the most important ceremonial centres (including Machu Picchu) of the Urubamba Valley also known as the Sacred Valley. In particular, Chachabamba investigations were conducted with two principal aims: (1) to give new impetus to archaeological research with targeted investigations aimed at improving and completing the site’s knowledge framework; (2) to experiment and validate an archaeogeophysical approach to be reapplied in other sites of the Urubamba valley, including Machu Picchu, having similar characteristics as those found in Chachabamba.