Gian Paolo Cavinato

Geostatistical interpolators for the estimation of the geometry of anthropogenic deposits in Rome (Italy) and related physical–mechanical characterization with implications on geohazard assessment

The role played by the anthropogenic deposits with poor geotechnical characteristics to induce seismic amplification and its influence on hydrogeological conditions, due to its permeability characteristics, has been demonstrated by numerous studies conducted in urban environments. The historical center of Rome (Italy) is characterized by the presence of high thickness of anthropogenic deposits, a stratigraphic unit that accumulated during the centuries of urban development. The modeled reconstruction of this unit could provide a tool for the elaboration of preliminary maps used for urban planning by public institutions. In this work, the reconstruction of the basal surface of the anthropogenic deposits was carried out using lithostratigraphical and geotechnical data recorded in 1355 boreholes drilled within the historical center of Rome. Deterministic and geostatistical estimators have been then used to predict the values at non-sampled locations to construct different maps of the basal surface. Grid statistics allowed the comparison of the obtained maps to select the best spatial predictor. Mono and multivariate geostatistical intepolators [ordinary kriging, kriging with external drift (KED) and cokriging] have been selected and discussed, and KED was the best interpolator for the used dataset. The obtained surface was then used to calculate a thickness map by subtracting it to the Digital Terrain Model. Furthermore, results of some mechanical characteristics of the anthropogenic deposits are presented and discussed in the light of the reconstructed geometry. The knowledge of both geometry (i.e., basal surface and thickness) and mechanical characteristics of these deposits could provide useful information for the evaluation of geological hazards in urban areas.

Seismic microzonation of Palatine hill, Roman Forum and Coliseum Archaeological Area

The protection of cultural heritage is an obligation that the Italian Constitution gives to the State. However, the protection of our heritage is a universal duty, one of those basic values that is a part of our way of feeling. It certainly is not necessary to argue the need to plan, finance and put into place all of the possible initiatives aimed at ensuring the protection and conservation of our cultural patrimony. Yet, this commitment is often considered insufficient to avert the danger that new losses may occur. It is almost expected that our cultural heritage will suffer damages, especially in exceptional cases of natural disasters. The understanding of the impotence that one feels when faced with the unexpected is an incentive to find a way to manage the “weaknesses” of our cultural heritage in order to contain and limit the magnitude of the loss. Studies recently done by institutes and organizations that operate on the national and international scale through analysis of past experiences are testimonies. The goal is to learn from the past and put in place instruments that allow us to at least mitigate the effects of natural calamities. Studies done by the Council of Europe through EUR-OPA, European and Mediterranean Major Hazards Agreement or the UNESCO World Heritage Centre-ICCROMICOMOS-IUCN manual of Managing Disaster Risks are, in this sense, interesting reference points.

Mapping the anthropic backfill of the historical center of Rome (Italy) by using intrinsic random functions of order k (IRF-k)

The historical centre of Rome is characterized by the presence of high thickness of anthropic cover with scarce geotechnical characteristics. This anthropic backfill could induce damages in urban areas, i.e. mainly differential settlements and seismic amplifications. About 1400 measurements from boreholes stored in the UrbiSIT database have been used to re-construct the anthropic backfill bottom surface by geostatistical techniques. The Intrinsic Random Functions of order k (IRF-k) was employed and compared with other interpolation methods (i.e. ordinary kriging and kriging with external drift) to determine the best spatial predictor. Furthermore, IRF-k allows to estimate by using an external drift as secondary information. The advantage of this method is that the modeling of the optimal generalized covariance is performed by using an automatic procedure avoiding the time-consuming modeling of the variogram. Furthermore, IRF-k allows the modeling of non stationary variables.

A physical stratigraphy model for seismic microzonation of the Central Archaeological Area of Rome (Italy)

A reliable litho-technical model for seismic microzonation requires a robust understanding of the subsoil architecture, that is essential to extrapolate in the space geognostic data that are often sparse. This paper presents the application to the level 1 seismic microzonation of the Central Archaeological Area of Rome of a complete methodological approach implementing physical stratigraphy concepts into an integrated analysis of a subsurface dataset. Particular emphasis has been placed on the reconstruction of buried geometries, distribution of lithofacies, and stacking pattern of geological bodies, which can control local seismic response. The spatial distribution of paleovalley infill and interfluves domains in the subsoil was reconstructed, which in virtue of their peculiar stratigraphy and morphology may determine 1D and 2D resonance effects. The summation of amplification effects due to the thick anthropogenic layer allowed to outline five stable zones prone to ground motion amplification, of which the most critical coincide with the narrow and deep infill of recent valleys. Potentially less prone to valley effects is the Middle Pleistocene paleovalley infill in the subsurface of the northern and eastern Palatine hill. Finally, the less hazardous zones correspond to the ancient, multilayered volcano-sedimentary interfluves separating the paleovalleys.

Seismic microzonation of level 1 of the historic center of Rome

In this note the seismic microzonation of level 1 of the historic center of Rome is presented. After a description of the subsoil model, which is primarily defined in terms of lithotypes and associated shear wave velocities, the results of the ambient noise measurements are presented and the fundamental frequencies are identified in the whole studied area. Finally, the homogeneous microzones in seismic perspective are described, in relation to seismic amplification and slope instability, and compared with damages from seismic events.

Pluvial flood hazard in the city of Rome (Italy)

ABSTRACT The map shows the result of a procedure for pluvial flood hazard (PFH) mapping in urban areas, developed by using easy to find data, usually available from local authorities. Data were processed using a sequence of tools in a GIS environment. Two parameters have been evaluated: (1) susceptibility, defined as the probability of a flood occurring in a certain area (‘flood-prone areas’) which depends on the ground morphology (i.e. presence of depressions, fill volume of depressions) and spatial density of previously observed floods and (2) potential impact, formed from all factors influencing the damage (e.g. value of exposed heritage or number of people potentially involved), as well as the induced hazard due to damage. Susceptibility and potential impact were each divided into five classes and a score matrix was constructed; the final PFH is then defined by the summation of the scores within the matrix. The methodology used is suitable for a comprehensive, mostly automatic, first-level analysis of PFH in urban areas, and it is easily replicable. The obtained flood hazard map could provide a useful tool for civil protection purposes, that is, for hazard evaluation and emergency planning.