http://hdl.handle.net/2122/71 2013-05-22T17:34:02Z 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. 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. 2012-11-30T23:00:00Z 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. 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. 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. 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. 2012-05-31T22:00:00Z http://hdl.handle.net/2122/8191 Title: Investigating the impact of surface wave breaking on modeling the trajectories of drifters in the northern Adriatic Sea during a wind-storm event Authors: Carniel, S.; CNR-ISMAR; Warner, J. C.; USGS; Sclavo, M.; CNR-ISMAR; Chigiato, J.; NURC Abstract: An accurate numerical prediction of the oceanic upper layer velocity is a demanding requirement for many applications at sea and is a function of several near-surface processes that need to be incorporated in a numerical model. Among them, we assess the effects of vertical resolution, different vertical mixing parameterization (the so-called Generic Length Scale –GLS– set of k–e, k–x, gen, and the Mellor–Yamada), and surface roughness values on turbulent kinetic energy (k) injection from breaking waves. First, we modified the GLS turbulence closure formulation in the Regional Ocean Modeling System (ROMS) to incorporate the surface flux of turbulent kinetic energy due to wave breaking. Then, we applied the model to idealized test cases, exploring the sensitivity to the above mentioned factors. Last, the model was applied to a realistic situation in the Adriatic Sea driven by numerical meteorological forcings and river discharges. In this case, numerical drifters were released during an intense episode of Bora winds that occurred in mid-February 2003, and their trajectories compared to the displacement of satellite- tracked drifters deployed during the ADRIA02-03 sea-truth campaign. Results indicted that the inclusion of the wave breaking process helps improve the accuracy of the numerical simulations, subject to an increase in the typical value of the surface roughness z0. Specifically, the best performance was obtained using aCH = 56,000 in the Charnok formula, the wave breaking parameterization activated, k–e as the turbulence closure model. With these options, the relative error with respect to the average distance of the drifter was about 25% (5.5 km/day). The most sensitive factors in the model were found to be the value of aCH enhanced with respect to a standard value, followed by the adoption of wave breaking parameterization and the particular turbulence closure model selected. 2008-12-31T23:00:00Z http://hdl.handle.net/2122/8190 Title: Layered structures in the upper Ligurian Sea Authors: Carniel, S.; CNR-ISMAR; Kantha, L.; Univ. of Colorado; Bergamasco, A.; CNR-ISMAR; Prandke, H.; ISW; Small, R. J.; NCAR; Sclavo, M.; CNR-ISMAR Abstract: During the dedicated sea-truth cruise LIGURE2007, a part of the intensive observational campaign Ligurian Sea Air-Sea Interaction Experiment (LASIE) performed in the eastern Ligurian Sea (Italy) from 16th to 23rd June in 2007, the R/V Urania carried out an intensive microstructure measurement program. Most of these measurements were made between 17th and 20th, in the vicinity of a spar buoy anchored 60 km off the coast in a region with a water column depth of approximately 1500 m; the prevailing light wind conditions and intense solar radiation limited the depth of the upper mixed layer to about 10–15m. We carried out measurements of the structure of the upper water column to a depth exceeding about 200 m. Interestingly, the microstructure measurements revealed multiple layers of relatively elevated dissipation and diffusivity rates around a depth of about 100 m. Since the water column is shown not to be not conducive to double-diffusion, these layered structures must have been produced by small-scale shear due to other processes, such as breaking internal waves. In this paper, we describe the oceanographic conditions prevailing at the time of the measurements, as well as the general turbulent properties in the upper part of the water column. In particular, the layered structures below the mixed layer are discussed in detail, with suggestions as to the likely origin and possible ways of investigating these processes. 2009-12-31T23:00:00Z http://hdl.handle.net/2122/8189 Title: Towards validating a last generation, integrated wave-current-sediment numerical model in coastal regions using video measurements Authors: Carniel, S.; CNR-ISMAR; Sclavo, M.; CNR-ISMAR; Archetti, R.; Univ. of Bologna Abstract: his paper presents the first steps in the implementation of a morphological numerical model to be applied in the Bevano River region, a shallow water area in the Adriatic Sea, with the aim of helping the identification and assessment of erosional patterns and bottom morphological modifications induced by severe marine storms. The numerical modeling, performed using a fully 3D coupled wave-current-sediment version of the ROMS model, has been complemented with in situ data analysis and observations: a first ... 2010-12-31T23:00:00Z http://hdl.handle.net/2122/8187 Title: Evidence of basaltic magma intrusions in a trachytic magma chamber at Pantelleria (Italy) Authors: Romengo, N.; Università di Palermo; Landi, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Rotolo, S. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: In the last 50 ka basalts have erupted outside the margin of the young caldera on the island of Pantelleria. The inner portion of the caldera has instead been filled by trachyte lavas, pantellerite lavas and pumice fall deposits. This paper focuses on a low-volume benmoreite lava topping the trachyte lava pile in the middle of the young caldera. The mineral chemistry, including trace elements in clinopyroxene (LA-ICP-MS), suggests that benmoreite is a hybrid product resulting from mixing between a trachytic magma and a basaltic end member even more primitive than those erupted during the past 50 ka. The principal inference is that basaltic magmas intruded the trachytic magma chamber below the caldera and were erupted in recent times within the caldera and not only beyond, as the distribution of basaltic centers would suggest. Data are used to discuss the relationship between felsic and mafic magmas at Pantelleria. 2011-12-31T23:00:00Z