http://hdl.handle.net/2122/67 Sat, 25 May 2013 19:28:14 GMT 2013-05-25T19:28:14Z http://hdl.handle.net/2122/8530 Title: Modellazione numerica agli elementi finiti per sistemi di faglie potenzialmente sismogenetiche nel territorio italiano, con particolare riferimento alla zona della sequenza sismica umbro-marchigiana del 1997 Authors: Finocchio, Debora; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia Abstract: Lo scopo fondamentale di questo lavoro è l’applicazione delle tecniche di modellazione numerica per lo studio di sistemi di faglie per verificarne il loro potenziale sismogenetico. Determinare quale faglia merita più attenzione, dal punto di vista del rischio sismico, è una questione attualmente ancora dibattuta. Lo confermano, ad esempio, i terremoti di l’Aquila nel 2009 e di Sumatra nel 2004. Inoltre, secondo uno studio di Wyss et al. (2012), il numero di morti causati dai recenti terremoti è da 100 a 1000 volte più elevato rispetto ai valori predetti dalla mappa mondiale di hazard. Le problematiche riguardanti le mappe di hazard dipendono principalmente dal fatto che sono calcolate mediante cataloghi sismici e dati di tipo geologico. Questo comporta un problema dal punto di vista temporale, in quanto i cataloghi sismici registrano eventi che non coprono un intero ciclo sismico, mentre i dati geologici contengono più eventi registrati, ad esempio, dal rigetto superficiale delle faglie. La questione temporale può essere risolta mediante la modellazione numerica che permette di raccordare i dati a lungo e corto periodo. Infatti, tramite la modellazione numerica, è possibile stimare l’evoluzione di una faglia (in superficie e in profondità) nel periodo intersismico e simulare il caso cosismico. Inoltre la modellazione numerica permette di distinguere le faglie bloccate da quelle sbloccate. Questa distinzione fornisce un elemento utile per valutare la possibilità di un’eventuale rottura. Inoltre è possibile stimare lo stress, la deformazione e la velocità di ricarica di un terremoto. Ho applicato la modellazione numerica a tre aree rappresentative del territorio italiano. Partendo dal centro Italia, ho studiato la faglia a basso angolo dell’Altotiberina e la sua relazione con le faglie di Colfiorito e della Valle Umbra. Ho approfondito lo studio delle faglie a basso angolo, analizzando il caso della faglia di Messina (Sud Italia). Infine, ho studiato l’area esterna del sud Alpino (nord Italia), caratterizzata da un sistema compressivo, che comprende il thrust del Montello ed il thrust di Bassano. Ho modellato numericamente ognuna di queste faglie o sistemi di faglie utilizzando diverse condizioni al contorno e parametri reologici in accordo con l’area di studio. I risultati sono stati confrontati con dati di tipo geodetico, geologico e geofisico. E’ stato possibile verificare che, la modellazione numerica fornisce un ottimo sostegno per la modellazione analogica, contribuendo a dare maggiore completezza al risultato e a simulare alcune proprietà dei materiali con grande precisione. Il risultato di un modello numerico varia principalmente al variare delle condizioni al contorno imposte, quindi dalla geometria, dai parametri reologici, e dal tipo di meccanismo utilizzato per riprodurre la deformazione di un’area. I risultati ottenuti in questo lavoro mostrano che la faglia Altotiberina è completamente bloccata al contrario della faglia di Colfiorito e la faglia della Valle Umbra che si muovono in parte come delle faglie sbloccate. Il campo deformativo dell’area sembra essere guidato da una trazione posta alla base della litosfera. Per quanto riguarda il sistema di thrust del Montello, ho potuto verificare che la porzione bloccata del thrust di Bassano ha un grande potenziale sismogenetico rispetto al thrust del Montello e al thrust antitetico al Montello, che risultano sbloccate. Assumendo che l’ampiezza delle faglie bloccate sia proporzionale all’ampiezza del terremoto, è stato possibile stimare la magnitudo massima attesa per ogni porzione di faglia bloccata, calcolata mediante la modellazione numerica. In particolare, la faglia di Bassano e la faglia Altotiberina sembrano avere un forte potenziale sismogenetico, in quanto potrebbe avere una magnitudo massima attesa di circa 7. Mon, 18 Feb 2013 23:00:00 GMT http://hdl.handle.net/2122/8530 2013-02-18T23:00:00Z http://hdl.handle.net/2122/8525 Title: Sequence stratigraphy, kinematics and dynamic geohistory of the Crotone Basin (Calabrian Arc, Central Mediterranean): an integrated approach Authors: van Dijk, J. P.; Eni Abstract: A comprehensive study of the Late Neogene tectonostratigraphic development of the Crotone Basin is presented. The basin is situated on the accretionary wedge along the external side of the Calabrian Arc (Central Mediterranean). The results of our analysis provide detailed insight into the relative role of local tectonic activity of the thrust wedge and regional relative sea level fluctuations in the creation of unconformity bound depositional sequences. The tectonostratigraphic significances of the sequence boundaries of the Early-Late Miocene and Late Pliocene-middle Pleistocene sequences are remarkably similar. They reflect a “composite tectonic event” comprising an uplift/regression pulse, followed by a rapid subsidence/onlap. Each composite tectonic event, in turn, represents one pulse in the progressive evolution of the accretionary wedge system. We regard the middle Messinian-Early Pliocene phases of basin fill and tectonic inversion, and the Late Pleistocene-Recent uplift phase as reflections of the increase of regional stress in the Central Mediterranean. Sun, 31 Dec 1989 23:00:00 GMT http://hdl.handle.net/2122/8525 1989-12-31T23:00:00Z http://hdl.handle.net/2122/8524 Title: Use of combined scaling of real seismic records to obtain code-compliant sets of accelerograms: application for the city of Bucharest Authors: Craifaleanu, I.-G.; Technical University of Civil Engineering Bucharest; Borcia, I. S.; National R&D Institute "URBAN-INCERC" Abstract: A recently proposed method for scaling real accelerograms to obtain sets of code-compliant records is assessed. The method, which uses combined time and amplitude scaling, corroborated with an imposed value of an instrumental, Arias-type intensity, allows the generation of sets of accelerograms for which the values of the mean response spectrum for a given period range are not less than 90% of the elastic response spectrum specified by the code. The method, which is compliant with both for the Romanian seismic code, P100-1/2006, and Eurocode 8, was described in previous papers. Based on dynamic analyses of single-degree-of freedom (SDOF) and of multi-degree-of-freedom (MDOF) systems, a detailed application and assessment of the method is performed, for the case of the long corner period design spectrum in Bucharest. Conclusions are drawn on the advantages of the method, as well as on its potential improvement in the future. Fri, 30 Nov 2012 23:00:00 GMT http://hdl.handle.net/2122/8524 2012-11-30T23:00:00Z http://hdl.handle.net/2122/8481 Title: Accompanying material of a paper Authors: Vesnaver, Aldo; KFUPM - OGS Sun, 20 Jan 2013 23:00:00 GMT http://hdl.handle.net/2122/8481 2013-01-20T23:00:00Z http://hdl.handle.net/2122/8392 Title: Assessment of the impact caused by natural disasters: simplified procedures and open problems Authors: Petrucci, Olga; CNR-IRPI Editors: Tiefenbacher, J.P. Abstract: A natural hazard is a geophysical, atmospheric or hydrological event (e.g., earthquake, landslide, tsunami, windstorm, flood or drought) that has the potential to cause harm or loss, while a natural disaster is the occurrence of an extreme hazard event that impacts on communities causing damage, disruption and casualties, and leaving the affected communities unable to function normally without outside assistance (Twig, 2007). The definition of natural disaster impact (NDI) can change according to both the aim of the study and the scientist assessing it. It can be defined as constituting the direct, indirect and intangible losses caused on environment and society by a natural disaster (Swiss Re, 1998). Direct losses include physical effects such as destruction and changes that reduce the functionality of an individual or structure. Damages to people (death/injury), buildings, their contents, and vehicles are included, as are clean-up and disposal costs. Indirect losses affect society by disrupting or damaging utility services and local businesses. Loss of revenue; increase in cost; expenses connected to the provision of assistance, lodging, and drinking water; and costs associated with the need to drive longer distances because of blocked roads are included. Intangible losses include psychological impairments caused by both direct and intangible losses that individuals personally suffer during the disaster. The Natural Disaster Impact Assessment (NDIA) is crucial in helping individuals to estimate replacement costs and to conduct cost-benefit analyses in allotting resources to prevent and mitigate the consequences of damage (UNEP-ECLAC, 2000). A general NDIA procedure has not yet been developed; several approaches are available in literature and their applicability depends on the accessibility of damage data. Possible end users of NDIA include the following (Lindell & Prater, 2003): 1. Governments, with an interest in estimating direct losses to report to taxpayers and to identify segments of the community that have been (or might be) disproportionately affected 2. Community leaders, who may need to use loss data after a disaster strikes to determine if external assistance is necessary and, if so, how much. 3. Planners, who can develop damage predictions to assess the effects of alternative hazard adjustments. Knowing both the expected losses and the extent to which those losses could be reduced makes it possible to implement cost-effective mitigation strategies. 4. Insurers, who need data on the maximum losses in their portfolios to guarantee their solvency or even to undertake additional measures to alleviate the risk that they would face in case of a disaster (i.e., the use of catastrophe bonds which are risk-linked securities that transfer a specified set of risks from a sponsor to investors) (Noy & Nualsri, 2011). Data availability and reliability, especially for old events, represent constraints in the NDIA context because of several issues of very different type: 1. Data availability, for current events, depends on the time at which data gathering started. It is impossible to decide a priori when data have to be gathered: it primarily depends on the type of phenomenon causing the disaster and its magnitude, and secondly on the scope of the assessment (for example, the assessment should not be unnecessarily delayed as there is an urgent need to elicit support from the international community) (ECLAC, 2003). 2. Long-term losses must sometimes be determined over a period of years. Slow landslides, for example, can cause damage over long periods. Intangible damage like disaster-related stress also requires years to be detected (Bland et al., 1996). 3. In most countries, there are no agencies responsible for gathering damage data. Damage caused by severest events can be mined from international databases, while data on less severe events can be obtained by means of specific historical studies. 4. Data on property damage can depreciate the value of property, thus they would not be available or not completely reliable (Highland, 2003). 5. For some type of disasters, as landslides or floods, the costs of damages to structures such as roads are often merged with maintenance costs and are therefore not labelled as damage. In addition, when heavy rains trigger both landslides and floods (Petrucci and Polemio, 2009), it is difficult to separate landslide damage from flood damage. 6. Developing countries have an incentive to exaggerate damage to receive higher amounts of international assistance; thus, in these cases, data may not be entirely reliable (Toya & Skidmore, 2007). This chapter starts with a panoramic of the different approaches reported in the literature to assess the impact of natural disasters, and then presents some simplified approaches to perform a relative and comparative assessment of the impact caused by phenomena as landslides and floods triggered by heavy rainfall during events defined as Damaging Hydrogeological Events. Finally, some indices to assess the relative impact of landslides are presented. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8392 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8386 Title: Tracking bottom waters in the Southern Adriatic Sea applying seismic oceanography techniques Authors: Carniel, S.; CNR-ISMAR; Bergamasco, A.; CNR-ISMAR; Book, J. W.; NRL; Hobbs, R. W.; Univ. of Durham; Sclavo, M.; CNR-ISMAR Abstract: We present the first results from the Seismic Oceanography (SO) cruise ADRIASEISMIC where we successfully imaged thermohaline fine structures in the shallow water environment (50-150 m) of the southern Adriatic Sea during March 2009 using a compact two GI-gun seismic source. The SO observations are complemented with traditional oceanographic and micro-structure measurements and show that SO can operate over almost the entire water column except (in our experimental layout) for the uppermost 50 m. After processing to enhance the signal-to-noise ratio, the seismic reflection data have a vertical resolution of ~10 m and a horizontal resolution of ~100 m and provide a laterally continuous map of significant thermohaline boundaries that cannot be achieved with conventional physical oceanography measurements alone. ADRIASEISMIC specifically targeted structures in shallow waters, namely along the western margin of the southern Adriatic Sea, between the Gargano peninsula and the Bari canyon, and imaged the Northern Adriatic Dense Water (NAdDW), a bounded cold and relatively dense water mass flowing from the northern Adriatic Sea. The seismic data acquired in Bari canyon and offshore of the Gargano promontory show many regions of strongly reflecting shallow structures, and the incorporation of XBTs measurements with these data demonstrate that they can be interpreted in terms of temperature structures and gradients. In the Gargano region several warm water intrusive structures are mapped along with the offshore transitional edge of cold waters of strong NAdDW influence. In Bari Canyon, waters with NAdDW influence are further mapped extending over the shelf and off the slope into a 5 km long tongue extending offshore between depths of 200-300 m. More generally, even though neither cascading nor open-ocean deep convection process appeared to be evident during March 2009, the SO approach was able to map details of thermal features not resolved by even closely spaced XBT measurements. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8386 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8372 Title: Integrated Numerical Models in Coastal Areas: An Example of Their Application in the North Adriatic Sea Authors: Carniel, Sandro; Sclavo, Mauro; Tondello, Massimo; Ciavola, Paolo Editors: Oddo, P Abstract: Recent decades have witnessed considerable developments in the field of integrated numerical models used for simulating dynamic processes in coastal areas, that can now provide quantitative support to decision makers for questions such as erosion and coastal vulnerability. Improvements in various theoretical formulations and an on-going increase in computing power (alongside the growing availability of long-term observations and numerical output from meteorological and sea-state models) allow the implementation of high-resolution and long-term applications.However, the efficient use of these numerical tools is a function of their capacity to describe a variety of physical processes that are ‘integrated’ amongst themselves correctly. Indeed, from the air-sea interface to the turbulent mixing of water masses and the water-sediment interaction, integrated numerical modelling has to face a series of scientific and practical challenges still open. Examples include the non-linear interaction of waves and currents, the problem of turbulence, the modelling of resuspension and sediment-transport processes, the role of longperiod waves in generating beach and dune erosion. Dealing with these using numerical models is necessary for a variety of reasons, from protecting the coast to search-and-rescue activities and support for marine construction work of all types. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8372 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8238 Title: A revision of the structure and stratigraphy of pre-Green Tuff ignimbrites at Pantelleria (Strait of Sicily) Authors: Rotolo, S. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Scailet, S.; Institut des Sciences de la Terre d'Orléans (ISTO) – INSU-CNRS – Université d'Orléans; La Felice, S.; Univ. di PAlermo, Dip. Scienze della TErra e del MAre; Vita Scailet, G.; Institut des Sciences de la Terre d'Orléans (ISTO) – INSU-CNRS – Université d'Orléans Abstract: At Pantelleria, peralkaline silicic magmas were erupted across a range of eruptive typologies and magnitudes: pyroclastic flows, Plinian to strombolian pumice fallout and lava flows. In this paper we focus on the intermediate cycle of eruptive activity which is bracketed by ignimbrite units slightly older than the two caldera collapses which marked the volcanological activity of the island. This age interval (180 - 85 ka) was punctuated by six ignimbrite-forming eruptions (silicic and variably peralkaline) for a cumulative erupted magma volume of approximately 6 km3 dense rock equivalent. Based on new 40Ar/39Ar (Na,K)-feldspar ages and petrographic data, we propose an updated volcanostratigraphic scheme for these welded and rheomorphic ignimbrites that can be summarised as follows: (i) the age of the old (‘La Vecchia’) caldera collapse is now tightly constrained between 139-146 ka and the caldera-forming eruption can be traced to a lithic-rich welded tuff breccia that outcrops in two opposite sectors of the island (south-west and north-east); (ii) four ignimbrite units previously considered unrelated are now merged in two distinct eruptive paroxysmal events at 107 and 85 ka. In particular, the 85 ka eruptive event is comparable in magnitude to the younger (caldera forming) Green Tuff Plinian eruption; (iii) the recurrence patterns of the 107 and 85 ka eruptions, compared to the Green Tuff, allow us to qualitatively assess that the climax in production of low-temperature silicic and peralkaline melt was focused in the age interval 85-45 ka. Mon, 31 Dec 2012 23:00:00 GMT http://hdl.handle.net/2122/8238 2012-12-31T23:00:00Z http://hdl.handle.net/2122/8222 Title: A Brownian Model for Recurrent Volcanic Eruptions: an Application to Miyakejima Volcano (Japan) Authors: Garcia-Aristizabal, A.; Center for the Analysis and Monitoring of Environmental Risk (AMRA); Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Fujita, E.; National Research Institute for Earth Science and Disaster Prevention (NIED) Abstract: The definition of probabilistic models as mathematical structures to describe the response of a volcanic system is a plausible approach to characterize the temporal behavior of volcanic eruptions, and constitutes a tool for long-term eruption forecasting. This kind of approach is motivated by the fact that volcanoes are complex systems in which a com- pletely deterministic description of the processes preceding eruptions is practically impos- sible. To describe recurrent eruptive activity we apply a physically-motivated probabilistic model based on the characteristics of the Brownian passage-time (BPT) distribution; the physical process defining this model can be described by the steady rise of a state variable from a ground state to a failure threshold; adding Brownian perturbations to the steady load- ing produces a stochastic load-state process (a Brownian relaxation oscillator) in which an eruption relaxes the load state to begin a new eruptive cycle. The Brownian relaxation os- cillator and Brownian passage-time distribution connect together physical notions of unob- servable loading and failure processes of a point process with observable response statistics. The Brownian passage-time model is parameterized by the mean rate of event occurrence, μ , and the aperiodicity about the mean, α . We apply this model to analyze the eruptive his- tory of Miyakejima volcano, Japan, finding a value of 44.2(±6.5 years) for the μ parameter and 0.51(±0.01) for the (dimensionless) α parameter. The comparison with other models often used in volcanological literature shows that this pysically-motivated model may be a good descriptor of volcanic systems that produce eruptions with a characteristic size. BPT is clearly superior to the exponential distribution and the fit to the data is comparable to other two-parameters models. Nonetheless, being a physically-motivated model, it provides an insight into the macro-mechanical processes driving the system. Wed, 29 Feb 2012 23:00:00 GMT http://hdl.handle.net/2122/8222 2012-02-29T23:00:00Z http://hdl.handle.net/2122/8221 Title: Basic principles of multi-risk assessment: a case study in Italy Authors: Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Garcia-Aristizabal, A.; Center for the Analysis and Monitoring of Environmental Risk (AMRA); Gasparini, P.; Center for the Analysis and Monitoring of Environmental Risk (AMRA); Mastellone, M. L.; Dipartimento di Scienze Ambientali, Seconda Universita' di Napoli; Di Ruocco, A.; Center for the Analysis and Monitoring of Environmental Risk (AMRA) Abstract: The assessment of the impact of different catastrophic events in a given area requires innovative approaches that allow risks comparison and that account for all the possible risk interactions. In the common practice, the risk evaluation related to different sources is generally done through independent analyses, adopting disparate procedures and time–space resolutions. Such a strategy of risks evaluation has some evident major drawbacks as, for example, it is difficult (if not impossible) to compare the risk of different origins, and the implicit assumption of independence of the risk sources leads to neglect possible interactions among threats and/or cascade effects. The latter may amplify the overall risk, and potentially the multi-risk index could be higher than the simple aggre- gation of single-risk indexes calculated considering each source as independent from the others. In this paper, we put forward some basic principles for multi-risk assessment, and we consider a real application to Casalnuovo municipality (Southern Italy), in which we face the problem to make different hazards comparable, and we highlight when and how possible interactions among different threats may become important. Thu, 31 May 2012 22:00:00 GMT http://hdl.handle.net/2122/8221 2012-05-31T22:00:00Z