Nasser Abu Zeid

Non-invasive sensing techniques have become a cornerstone in the study and preservation of Cultural Heritage. These techniques offer a means to investigate the internal structure and surface properties of precious and delicate objects without causing damage. This article is the second of three review articles exploring contact and non-contact imaging methods applied to Cultural Heritage at various scales encompassing micro- (i.e., manufacts), meso- (sites), and macro-scales (landscapes). The unifying factor of these techniques is their ability to infer variations in geometrical and physical properties across inspected surfaces or volumes. This allows researchers to discover new historical sites, map their spatial extent, and characterize their material features at different scales, from landscapes to artifacts. This second part focuses on the meso-scale, encompassing the inspection, documentation, study, and characterization of historical and archeological sites, monuments, and submerged sites, using both contact and remote sensing techniques.

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 image their spatial extent and material features at different scales, from landscape to artifact. This first part concentrates on the micro-scale, i.e., inspection, study and characterization of small objects (ancient papers, paintings, statues, archaeological findings, architectural elements, etc.) from surface to internal properties.

In the framework of the III level Seismic Microzonation of the Pieve del Grappa municipality (Treviso, NE Italy), three paleoseismological trenches were dug, in order to investigate activity and capacity of the Crespano del Grappa backthrust. The study area is located in the Veneto foothills, where the Plio-Quaternary external front of the Eastern Southern Alps (Castellarin and Cantelli, 2000) presently propagates with a 2-3 mm/y velocity towards the south (Serpelloni et al., 2016). The external front is composed of a series of arcuated WSW-ENE striking, S verging structures (Galadini et al, 2005). Moreover, the area is characterized by a medium-to-low seismicity with only one M>6 earthquake during the last millennium: the 1695 Asolo event, Mw 6.45 (Rovida et al., 2016). Regarding the structural framework, the study area is located between the Bassano-Vittorio Veneto Thrust to the north and the Bassano-Cornuda Thrust to the south. The investigated tectonic structure, i.e. the Bassano-Cornuda backthrust, is a N-verging E-W striking reverse structure. Moving from east to the west, it widely crops out near the Castelcucco village, causing a hundred meters displacement in the Miocene Molasse (Braga, 1970). In particular in Crespano village the thrust is responsible of an about 10 m vertical throw in the Quaternary alluvial conglomerates of Lastego river (Parinetto, 1987). Because of the urbanization, the paleoseismological trenches were realized at the eastern (Col Canil) and western (San Vito) borders of the village. In the former case, the trench cut through thick colluvial deposits that probably buried an abandoned valley. Differently, the second and the third trenches affected wide coalescent LGM alluvial fans, which border the southern slope of Mt. Grappa. The results testify an intense Pleistocene-Holocene deformation of the Crespano del Grappa backthrust. Particularly, active deformation evidence deals with: back-tilting of the Holocene colluvial units; pronounced polyphasic liquefaction episodes, locally completely altering the sedimentary structures of colluvial units; a wide damage zone in the proximity of the morphological scarp and associated with the peak of the induced polarization. This observation testifies that the Crespano del Grappa backthrust reached the surface and displaced topography in the past, probably at the occurrence of one or more events which generated the paleoliquefaction effects; the 3-4 m displacement of the LGM alluvial fan deposits. Concerning the age of the deformation, the dating of the involved units suggests a post LGM activation, probably recent-to-historical.   REFERENCES Braga GP, 1970. Rendiconti Fisici dell’Accademia dei Lincei, serie 8, 48(4): 451-455. Castellarin A. and Cantelli L., 2000. Journal of Geodynamics. DOI: 10.1016/S0264-3707(99)00036-8. Galadini et al., 2005. Geophysical Journal International. DOI: 10.1111/j.1365-246X.2005.02571.x. Parinetto A., 1987. Aspetti morfotettonici del versante meridionale del Grappa e delle colline antistanti. Unpublished degree thesis. University of Padova, Italy. Rovida et al., 2016. DOI: http://doi.org/10.6092/INGV.IT-CPTI15. Serpelloni et al., 2016. Tectonophysics, https://doi.org/10.1016/j.tecto.2016.09.026.

In this article, a framework of building monitoring is developed and transient and permanent variations of the fundamental period of vibration caused by both damage and repair interventions are investigated. The buildings of the University of Ferrara (Emilia-Romagna Region, Northern Italy), struck by the 2012 Emilia seismic sequence, were monitored using both temporary and permanent equipment: the first one to perform ambient vibration tests and the second one to implement permanent real-time monitoring for earthquake recording. Three on-demand ambient vibration tests were performed at each floor of the buildings: the first dataset was acquired a few months before the mainshock occurred on 20 May 2012 ( M_L = 5.9, 6.8 km depth and 30 km epicentral distance); the second was acquired right after the end of the sequence, when the building showed slight damage (degree 1 according to the European Macroseismic Scale 98); finally, the third dataset was acquired in 2016 after the repair intervention. The data analysis clearly documented the permanent drop of the first vibration frequency as a symptom of the damage and its partial recovery that followed the repairs. The permanent real-time monitoring system, despite the fact that it was implemented using low-cost sensors, provided an insight into the intra-event frequency variation, allowing in turn a preliminary damage assessment.

Geophysical techniques are seldom used for the investigation of paleolithic archeological sites, mostly due to their sedimentary nature and the almost complete absence of architectural remains that can result in clear geophysical anomalies. The Fumane cave (Italy) is considered one of the most important sites in Europe. Recent investigations and studies carried out by the archaeological group of the Dep. Of Humanities (University of Ferrara) with the enrollment of the Department of Engineering of the same University allowed for the reconstruction of the 3D model of the Fumane Cave. This offered an opportunity for the applied geophysics group of the same university to assess the capability of Electrical Resistivity Tomography to retrieve subsurface information of archaeological interest. As primary goals, the study aimed at the creation of a three-dimensional resistivity model of the subsurface, to infer the nature of the sedimentary infill, so enabling a better understanding of the depositional processes involved in the formation of this important archaeological deposit and at the same time, for planning long-term field-investigations and to locate areas interesting for excavation. Moreover a Ground penetrating radar and a Nakamura survey were attempted in an integrate approach to test whether the combined methodologies could provide further insight about the subsurface. With respect to previous work, we present new and improved results both on ERT, GPR and HVSR. In particular, the HVSR test was accomplished to gain information about the maximum thickness of the deposit and to see if other impedance contrast discontinuities are present as was anticipated by previous archaeological studies. Presentation Date: Monday, September 25, 2017 Start Time: 3:05 PM Location: 360C Presentation Type: ORAL

In the framework of a geophysical survey at the “Pilastri Terramara” Middle Bronze Age archeological site (Northern Italy), which aimed at using cost-effective approaches to investigate a 12.000 m² portion of land, we verified that in this site the most commonly used GPR, magnetometry and ERT geophysical methods were hampered by specific unfavorable conditions. Since the main purpose of the survey was to obtain information on ancient walking surfaces, we speculated that compaction, caused by the trampling of human activity over centuries, increased both density and seismic velocity of these paleo-surfaces. Assuming that such compacted layers still lie embedded in the shallow subsurface we successfully used the Horizontal-to-Vertical Spectral Ratio of microtremors, popular as HVSR, as a mapping tool. HVSR technique is seldom used in archaeological studies. The curve obtained by this method shows peaks and features that can be associated to the elastic impedance contrasts of a layered subsurface. Results from a previous single-station HVSR survey carried out on the whole area and consisted of 67 measurement points, allowed to obtain an indication about acoustic impedance contrasts and to spot few anomalies. The preliminary, yet promising result however, needed further acquisitions in order to achieve a better spatial sampling. We then tested microtremors acquisition using a linear array of seismic prospection geophones (4.5 Hz proper frequency) which have a worse response with respect the short period sensor used in single-station configuration. Yet the use of the array allowed for a comparable mapping of both paleo-surfaces and anomalies and data collection was performed at 24 locations simultaneously, so greatly accelerating the field work. In the following the two approaches are compared and an anomaly is highlighted which was located outside the hypothesized Bronze Age settlement area. Once excavated, such feature revealed to be a layer of roman age remains. Further, we show our best GPR section over the same anomaly. An indication was present in the GPR section but this became clear only afterward. Presentation Date: Monday, September 25, 2017 Start Time: 2:40 PM Location: 360C Presentation Type: ORAL

Horizontal‐to‐vertical spectral ratio (HVSR) is a widely used geophysical technique in seismic microzonation studies. It is based on a specific analysis of seismic ambient noise. The method allows to obtain the frequency and amplitude of the resonance peaks of a layered earth with increasing acoustic impedance contrasts. The peaks can be interpreted to obtain an estimation of depth(s) of the impedance contrast horizon(s).Based on the assumption that long‐term human trampling results in sediment's stiffening, which increased both density and velocity of seismic shear waves, the HVSR method was applied to investigate the shallow subsurface of an important, Middle Bronze Age, archaeological site called ‘Pilastri Terramara’ discovered at the end of the last century.Following recent excavations, archaeologists supposed that the settlement could extend outside the initially hypothesized borders, and decided to involve geophysicists to verify the truthiness of this new hypothesis and consequently to map the possible spatial extent of the paleo‐surfaces frequented by ancient occupants. The purpose of the geophysical investigation was then to detect and possibly to map one or more anthropogenic paleo‐surfaces over a relatively large area (about 12000 m²).Unfortunately, direct evidences showed that the paleo‐surfaces were embedded in clayey sediments and laying at depths ranging between 50 and 170 cm below ground level. Furthermore, the area to be investigated is occupied by a farm with glasshouses and other buildings. These obstacles constituted a real challenge that hindered the utilization of the most commonly used geophysical methods in archaeology, i.e. ground penetration radar (GPR), magnetometry and electrical resistivity tomography. For these reasons, we decided to use the HVSR method as a reconnaissance exploration tool, to confirm or rule out the presence of such paleo‐surfaces.Spectral peaks related to acoustic horizons provided evidences about their presence and allowed to estimate their depths as was later confirmed by a new excavation. Copyright © 2017 John Wiley & Sons, Ltd.