Massimiliano Moscatelli

Macroseismic effects highlight site response in Rome and its geological signature

A detailed analysis of the earthquake effects on the urban area of Rome has been conducted for the L’Aquila sequence, which occurred in April 2009, by using an online macroseismic questionnaire. Intensity residuals calculated using the mainshock and four aftershocks are analyzed in light of a very accurate and original geological reconstruction of the subsoil of Rome based on a large amount of wells. The aim of this work is to highlight ground motion amplification areas and to find a correlation with the geological settings at a subregional scale, putting in evidence the extreme complexity of the phenomenon and the difficulty of making a simplified model. Correlations between amplification areas and both near-surface and deep geology were found. Moreover, the detailed scale of investigation has permitted us to find a correlation between seismic amplification in recent alluvial settings and subsiding zones, and between heard seismic sound and Tiber alluvial sediments.

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.

GIS-based hydrostratigraphic modeling of the city of Rome (Italy): analysis of the geometric relationships between a buried aquifer in the Tiber Valley and the confining hydrostratigraphic complexes

A preliminary hydrostratigraphic model of the city of Rome (Italy) was completed through the analysis of geological and hydrogeological data, and by using geographic information system (GIS)-based operations. The complex lithostratigraphic setting of a local Quaternary volcano-sedimentary multilayer was simplified into hydrostratigraphic complexes considering textural properties of terrains and hydraulic conductivity values. The Tiber River Valley, in the middle of the urban area, was analyzed separately from the surrounding areas. GIS tools were used in a multiple-step procedure to reconstruct the geometry of bounding surfaces of the main hydrostratigraphic complexes. Particular care was given to the characterization of a confined gravelly aquifer lying at the base of the upper Pleistocene–Holocene alluvium that fills the Tiber Valley. Updated isobaths and thickness maps of this layer were produced. Three-dimensional reconstruction identifies areas of potential recharge between the alluvium aquifer and the surrounding hydrostratigraphic complexes. In the central sector of the city, the gravel deposits are laterally confined by a thick aquitard corresponding to the Pliocene clayey bedrock of the city; in contrast, a potential recharge area can be hypothesized in the northern areas, where the upper Pleistocene–Holocene valley cross cuts the Paleotiber Graben, filled with older and highly permeable gravels and clays.RésuméUn premier modèle hydrostratigraphique de la Ville de Rome (Italie) a été finalisé grâce à l’analyse des données géologiques et hydrogéologiques et à la mise en oeuvre d’applications basées sur un système d’information géographique (SIG). La configuration lithostratigraphique complexe d’un multi-couche volcano-sédimentaire local d’âge quaternaire a été schématisée en des complexes hydrostratigraphiques définis par les propriétés texturales des terrains et les valeurs de la conductivité hydraulique. La Vallée du Fleuve Tibre, au cœur de l’aire urbaine, a été analysée à part des zones environnantes. Les outils du SIG ont été mis en œuvre en suivant une démarche multi-phasée, destinée à reconstituer la géométrie des surfaces délimitant les principaux complexes hydrostratigraphiques. Un soin particulier a été apporté à la caractérisation de l’aquifère graveleux captif présent à la base des alluvions du Pléistocène–Holocène supérieur qui comblent la vallée du Tibre. Les isobathes actualisées et les cartes d’épaisseur de cette couche ont été établies. La reconstitution en 3D identifie des secteurs de recharge potentielle entre l’aquifère alluvial et les complexes hydrostratigraphiques environnants. Dans le secteur central de la ville, les dépôts graveleux sont confinés latéralement par un aquitard épais correspondant au substratum argileux pliocène de la ville ; par contraste, une zone de recharge potentielle peut être supposée dans les quartiers nord où une vallée confluente Pléistocène–Holocène supérieur recoupe le Graben du Paléo-Tibre, comblé par des graviers et des sables plus anciens et fortement perméables.ResumenSe completó un modelo hidroestratigráfica preliminar de la ciudad de Roma (Italia) a través del análisis de datos geológicos e hidrogeológicos, y por el uso de operaciones basadas en un sistema de información geográfica (SIG). La compleja configuración litoestratigráfica de una multicapa local volcano – sedimentario del Cuaternario se simplificó en complejos hidroestratigráficos considerando las propiedades texturales de los terrenos y los valores de conductividad hidráulica. El valle del Río Tiber, en el medio del área urbana, fue analizado separadamente de las áreas circundantes. Herramientas SIG fueron usadas en un procedimiento múltiples pasos para reconstruir la geometría de las superficies circundantes de los principales complejos hidroestratigráficos. Se prestó particular cuidado a la caracterización del acuífero gravoso confinado que yace en la base del aluvio Pleistoceno superior–Holoceno que rellena el valle del Tiber. Se produjeron Isobatas actualizadas y mapas de espesores de esta capa. La reconstrucción 3D identifica áreas de recarga potencial entre el acuífero aluvial y los complejos hidroestratigráficos circundantes. En el sector central de la ciudad, los depósitos de gravas están lateralmente confinados por un acuitardo espeso correspondiente a la base arcillosa del Plioceno de la ciudad; en contraste, se puede introducir la hipótesis de un área potencial de recarga en las áreas del norte, donde el cruce del valle Pleistoceno superior–Holoceno corta el graben Paleotiber, rellenado con viejas y altamente permeables gravas y arenas.摘要意大利罗马城的一个初步水文地层模型通过地质与水文地质数据的分析已完成,并且利用了基于运算的地理信息系统(GIS)。考虑到地形的结构特性和渗透系数,当地的第四系火山多层沉积的复杂地层设置在水文地层综合体中被简化。Tiber河谷位于市区中心,与周围地区分开分析。GIS工具用于多步骤重建主要水文地层综合体的边界面的几何形状。特别注意到了布满整个河谷的位于更新世—全新世冲积层基底之上的承压砾石含水层。该层的更新的等深线和厚度图已完成。3D重建标识冲积含水层和周围水文地层综合体之间的潜在补给区。在城市的中心区,砾石沉积侧向被厚层弱透水层封闭,其与城市的上新世粘土基岩一致;相反地,潜在补给区可以假定为北边的区域,其上更新世—全新世河谷横切Paleotiber 地堑,充填了更老的和高渗透性的砾石和砂。RiassuntoUn modello preliminare della città di Roma (Italy) e’ stato completato attraverso l’analisi di dati geologici ed idrogeologici, ed attraverso l’uso di operazioni basate su sistemi informativi geografici (GIS). Il complesso assetto litostratigrafico del multistrato vulcano-sedimentario del Quaternario è stato semplificato in complessi idrostratigrafici considerando le proprietà tessiturali dei terreni e i valori di conducibilità idraulica. La Valle del fiume Tevere, posta nel mezzo dell’area urbana, è stata analizzata separatamente. Funzionalità GIS sono state utilizzate in una procedura articolata per ricostruire la geometria delle superfici di tetto dei principali complessi idrostratigrafici. Particolare cura è stata data alla caratterizzazione di un acquifero ghiaioso che si trova alla base delle alluvioni pleistoceniche–oloceniche che riempiono la Valle del Tevere. Sono state realizzate nuove mappe delle isobate e dello spessore di questo strato. Tramite una ricostruzione 3D sono state identificate le aree di potenziale ricarica tra l’acquifero alluvionale e i circostanti complessi idrostratigrafici. Nel settore centrale della città i depositi ghiaiosi sono confinati lateralmente da uno spesso aquiclude che corrisponde al bedrock argilloso della città; al contrario, un’area di potenziale ricarica può essere ipotizzata più a nord, laddove la valle pleistocenica–olocenica è incisa nel graben del Paleotevere, riempito da ghiaie e argille più antiche e ad alta permeabilità.ResumoConcluiu-se um modelo hidroestratigráfico preliminar da cidade de Roma (Itália) através da análise de dados geológicos e hidrogeológicos, efetuado com base em operações que utilizam sistemas de informação geográfica (SIG). Para o efeito, a complexa configuração litoestratigráfica multicamada do Quaternário vulcano-sedimentar foi simplificada em complexos hidroestratigráficos, considerando as propriedades texturais dos terrenos e os seus valores de condutividade hidráulica. O Vale do Rio Tibre, no meio da área urbana, foi analisado separadamente das áreas circundantes. Utilizaram-se ferramentas SIG para um procedimento de reconstrução sucessivo da geometria dos limites dos principais complexos hidroestratigráficos. Foi tido um especial cuidado na caraterização de um aquífero confinado de cascalho sob a base do aluvião Plistocénico superior–Holocénico que preenche o Vale do Tibre. Foram produzidos mapas de isobatimétricas e de espessura desta camada. A reconstrução 3D identifica áreas de recarga potencial do aquífero entre o aquífero aluvionar e os complexos hidroestratigráficos envolventes. No setor central da cidade, os depósitos de cascalho são confinados lateralmente por um espesso aquitardo correspondente ao soco argiloso Pliocénico da cidade; em contraste, pode ser considerada como hipótese uma área potencial de recarga nas áreas a norte, onde o vale Plistocénico superior–Holocénico corta o Graben de Paleotiber, preenchido com cascalhos e areias mais antigos, altamente permeáveis.

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.

Seismic microzonation of the central archaeological area of Rome: results and uncertainties

The paper summarizes the results of a multidisciplinary study aimed at seismic microzonation of the Central Archeological Area of Rome including the Palatine hill, Roman Forum and Coliseum. A large amount of subsoil data, available mainly from adjacent subway lines and from the archaeological superintendence, were collected and used to plan new multidisciplinary investigations, carried out in 2010–2011. First, the paper describes the integrated subsoil model aimed at numerical modeling of site effects. The results of equivalent linear 2D site response analyses carried out on seven representative cross-sections of the area are then presented and discussed. Ground motion amplification factors defined in terms of Housner Intensity were computed in different ranges of period, covering the different fundamental vibration periods pertaining to the monuments and structures. The contouring of amplification factor values from all the numerical simulations, based on morphological and geological constrains, eventually allowed to create microzonation maps. Finally, a sensitivity study was carried out to investigate the effects of uncertainties of input parameters and soil heterogeneity on microzonation.

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.

The Laga Basin: stratigraphic and structural setting

Most of the ancient turbidite systems are known being deposited in foredeep basins at the front of active thrust belt. Differently from fluvio-deltaic systems generally lacated in the more internal portion of these basins, the turbidite systems occur at different depth in the more deeper portions of these basins (foredeep turbidite systems) or in the relatively shallower tectonically confined depressions occurring on top of the thrust belt (wedge-top turbidite systems) (see discussion in Mutti et al. 2002, 2003). Foredeep turbidite systems represent the classical sedimentation in a broad and flat basin plain, showing thick to thin parallel and continuous sandstone beds with the Bouma-type depositional division. Wedge-top turbidite systems are directly fed by fluvio-deltaic systems and more clearly record both climate changes affecting the source areas and tectonic activity of the orogenic wedge. Messinian turbidite deposits of the northern and central Apennines show many characters indicating sedimentation in confined basins, formed since the upper Tortonian in relation to the segmentation of the Langhian-lower Tortonian Marnoso- Arenacea foredeep basin (inner stage of the Marnoso-Arenacea, Ricci Lucchi, 1986). In these last years, detailed facies and physical stratigraphic analyses as a well as structural and thermal analyses, conducted on the Laga and Argilloso-Arenacea Fms (central Apennines), demonstrate as these basins were located at the hinge between foredeep and wedge-top depozones of the Messinian Apennine thrust belt (Milli and Moscatelli, 2000, 2001; Bigi et al., 2003; Moscatelli, 2003; Milli et al., 2004; Falcini et al., 2006; Stanzione et al., 2006; Casero and Bigi, 2006; Aldega et al., 2006; Critelli et al., 2007; Milli et al., 2007). Anisotropy of the subducted plate and thrust propagation rate deeply controlled the onset of complex basins at the top of the orogenic wedge (Casero and Bigi 2006; Bigi et al., 2006). The resulting topography of these basins and the concomitant climate changes exerted a strong control on turbidite sedimentation and on the stratigraphic organization of these deposits.

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.

Evaluating groundwater resource of an urban alluvial area through the development of a numerical model

AbstractAs established in the European Water Framework Directive, the development of groundwater numerical models is fundamental for adopting water management plans aimed at preserving the water resource and reducing environmental risks. In this paper, authors present a methodology for the estimation of groundwater resource of an alluvial valley, in an urban area characterized by a complex hydrostratigraphic setting and scarcity of hydrogeological data; the study area is the urban and sub-urban area of Rome (Italy). A previous, elaborated hydrostratigraphic model set the base for the development of 3D, steady state, sub-basin scale numerical model, implemented by the finite-difference code MODFLOW 2000®; the water system components were derived by elaboration of available data. The alluvial aquifer of the Tiber River Valley, which runs in the middle of the City in a NNW–SE direction, has been analyzed in detail, since it is covered by a densely populated area hosting most of Rome’s historical heritage, and it is characterized by low quality geotechnical parameters. Results suggest that in areas with high hydrostratigraphic complexity and scarcity of hydrogeological data, a sub-basin scale, and steady-state numerical model can be very helpful to verify the conceptual model and reduce the uncertainty on the water budget components. The proposed steady-state model constitutes the base for future applications of transient state and local scale models, required for sustainable water management.