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Bevilacqua, Andrea
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Bevilacqua, Andrea
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andrea.bevilacqua@ingv.it
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134 results
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- PublicationOpen AccessELICIPY 1.0: A Python online tool for expert elicitation(2024)
; ; ; ; ; ; ; Structured expert judgment is crucial when dealing with significant epistemic and aleatoric uncertainties, particularly in probabilistic hazard assessments, where decisions based on uncertain information are often critical. In structured expert elicitations, participants are asked to quantify their uncertainty judgments by providing their percentile estimates of numerical values for a set of questions. More specifically, performance-based elicitations start with ‘‘seed’’ questions for determining experts’ uncertainty quantification skill. The performance scores are thus used to define each expert’s weight to be applied when considering their judgments on ‘‘target’’ questions, i.e., the actual variables of interest for the case study. In this paper we describe ELICIPY, a new Python tool which allows to perform expert elicitation sessions in a framework that covers both the questionnaire collection and the analysis parts, an approach that simplifies the work normally done by the analyst(s). This is achieved through the automatic generation of online webforms to collect the experts’ answers, their check for consistency and, finally, their analysis using different weighting schemes. The tool automatically produces outputs in different formats and creates a pptx presentation file available just after the collection of the answers.65 8 - PublicationOpen AccessDynamic updates of vent opening probability maps, probability of eruptions, and PDC hazard assessment at Campi Flegrei, using monitoring data (first report)Riunione progetto FISR Sale Operative Integrate e Rete di monitoraggio futuro WP3 Nuovi Dati e Misure ‐ Coordinatore: F. Guglielmino (OE) TASK 2 ‐ NUOVI MODELLI Attività: 2.5.1 ‐ Aggiornamento dinamico delle mappe di probabilità di apertura bocche eruttive, probabilità di occorrenza dell’eruzione e pericolosità da flussi piroclastici ai Campi Flegrei, tramite dati di monitoraggio. Referente: A. Neri (PI) Personale coinvolto nell'attività: Augusto Neri (PI), Andrea Bevilacqua (PI, precedentemente University at Buffalo), Mattia de Michieli Vitturi (PI), Tomaso Esposti Ongaro (PI), Flora Giudicepietro (OV), Roberto Isaia (OV), Giovanni Macedonio (OV), Stefano Vitale (OV, UNINA). Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa.
31 43 - PublicationOpen AccessDynamic updates of vent opening probability maps, probability of eruptions, and PDC hazard assessment at Campi Flegrei, using monitoring data (second report)Riunione progetto FISR «Sale Operative Integrate e Reti di monitoraggio del futuro» WP3 Nuovi Dati e Misure ‐ Coordinatore: F. Guglielmino (OE) TASK 2 ‐ NUOVI MODELLI Attività: 2.5.1 ‐ Aggiornamento dinamico delle mappe di probabilità di apertura bocche eruttive, probabilità di occorrenza dell’eruzione e pericolosità da flussi piroclastici ai Campi Flegrei, tramite dati di monitoraggio. Referente: A. Neri (PI) Personale coinvolto nell'attività: Augusto Neri (PI), Andrea Bevilacqua (PI, precedentemente University at Buffalo), Mattia de Michieli Vitturi (PI), Tomaso Esposti Ongaro (PI), Flora Giudicepietro (OV), Roberto Isaia (OV), Giovanni Macedonio (OV), Stefano Vitale (OV, UNINA). Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa.
39 24 - PublicationOpen AccessEstimates and models of the statistical dependence between local earthquakes and flank eruptions at Mt. Etna volcano (Italy): an old topic revised through new (historical) data(2019)
; ; ; ; ; ; ; ; ; ; ; ; ; Our study focuses on the estimation of the correlation between flank eruptions at Mt. Etna volcano and the pre-eruptive, syn-eruptive, and post-eruptive local seismicity, with the final purpose of improving the quantitative multi-hazard assessments. This research was motivated by the lateral eruption started at Etna on Dec. 24th 2018, that was followed by an intense seismic swarm producing a destructive earthquake (Mw 4.9, Dec. 26th) along the nearby Fiandaca fault. Indeed, earthquakes and eruptions at Etna are well known to be often occurring close in time, and a full probabilistic assessment would be very useful for civil protection purposes. The study relies on a few investigations developed in the 80s and 90s, which tested various statistical methods on the datasets available at that time, and the more recent research projects which provided more complete and extended databases on the eruptive and seismic phenomena. In particular, first we performed a time series analysis of both the seismic and eruptive records in the last 130-150 years, which are not affected by significant underrecording issues. We included the estimation of event rate and rate changes in time, and the description of spatial location and scale parameters (e.g. earthquake magnitude, erupted volume). Then, we accomplished a statistical analysis of the inter-event times, either between events of the same type, or between earthquakes and eruptions. Finally, we implemented a series of statistical tests aimed at the quantitative estimation of the correlation strength and its duration. The analyses were then conditioned on specific magnitude thresholds or spatial constraints (epicenters’ distribution vs eruptive fissure/vent location), with the purpose of further exploring the behavior of the coupled volcano-tectonic system.129 19 - PublicationOpen AccessData uncertainty management in volcanic hazard assessment: review and examples(2017)
; ; ; ; ; ; ; The availability of new volcanological data employed as input parameters in numerical models have allowed scientist over the past years to produce more accurate hazard maps. However, it is also true that these latter products, which are fundamental for decision-makers when dealing with long-term planning or with the management of emergency situations, might be affected by a certain degree of uncertainty. This latter one depends on many factors, and it is important to quantify the two main sources of uncertainty of a volcanic system: i) the first one related both to the incomplete knowledge of the system under investigation and to errors in data acquisition (epistemic uncertainty); ii) the second one related to the intrinsic physical variability of the system (aleatoric uncertainty). If a volcanic hazard map might be provided to civil protection authorities and decision-makers with a quantification of these sources of uncertainty, the resultant emergency planning might be undertaken with a better awareness. This presentation is therefore aimed at briefly reviewing the state of the art of the distinction between different types of uncertainty applied to volcanic hazard assessment: after a theoretical introduction, two examples from two Italian high-risk volcanoes (Vesuvio and Campi Flegrei) will illustrate how data uncertainty has been managed in specific cases related to volcanic hazard assessment.67 30 - PublicationOpen AccessProbabilistic hazard modeling of secondary pyroclastic avalanches generated by paroxysms at Stromboli (Italy)(2022)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The remobilization and avalanching of fresh pyroclastic deposits are relatively common at Stromboli. They are usually confined to the Sciara del Fuoco (SdF), a steep depression on the northwestern side of the island. However, at least during the Strombolian paroxysms in 1944, 1930, and possibly in 1906, pyroclastic avalanches occurred out of SdF, flowed in the valleys on the volcano flanks, inundated regions at low elevation, and, finally, they reached the sea and produced vaste temporary deltas. In particular, in the 1930 event, the pyroclastic avalanche reached San Vincenzo village, causing victims and damage to the buildings. In this study we perform an uncertainty quantification on the inputs of the 2D depth-averaged model, preliminary to a comparison with the available field data. In particular, because the source location of the flow is also assumed uncertain, we adopt a simplified source zonation based on the analysis of topographic slopes, distance from the eruptive craters, and watersheds basins in the upper part of the island, where thick tephra deposits could more likely accumulate during a future paroxysm.50 16 - PublicationOpen AccessThe Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy)(2017)
; ; ; ; ; ; ; ; ; ; ; ; ;; ;This study presents a new method for producing long-term hazard maps for pyroclastic density currents (PDC) originating at Campi Flegrei caldera. Such method is based on a doubly stochastic approach and is able to combine the uncertainty assessments on the spatial location of the volcanic vent, the size of the flow and the expected time of such an event. The results are obtained by using a Monte Carlo approach and adopting a simplified invasion model based on the box model integral approximation. Temporal assessments are modeled through a Cox-type process including self-excitement effects, based on the eruptive record of the last 15 kyr. Mean and percentile maps of PDC invasion probability are produced, exploring their sensitivity to some sources of uncertainty and to the effects of the dependence between PDC scales and the caldera sector where they originated. Conditional maps representative of PDC originating inside limited zones of the caldera, or of PDC with a limited range of scales are also produced. Finally, the effect of assuming different time windows for the hazard estimates is explored, also including the potential occurrence of a sequence of multiple events. Assuming that the last eruption of Monte Nuovo (A.D. 1538) marked the beginning of a new epoch of activity similar to the previous ones, results of the statistical analysis indicate a mean probability of PDC invasion above 5% in the next 50 years on almost the entire caldera (with a probability peak of 25% in the central part of the caldera). In contrast, probability values reduce by a factor of about 3 if the entire eruptive record is considered over the last 15 kyr, i.e., including both eruptive epochs and quiescent periods.1076 109 - PublicationOpen AccessUsing multi-model and coupled model based simulations and UQ for analysis of volcanic hazards(2016)
; ; ; ; ;This presentation will focus on the systematic use of multiple models (resulting from different assumptions on rheologies for the mass flows resulting from volcanic debris avalanches), coupled models (resulting from the coupling of eruption models and plume/transport models) and UQ for analysis of volcanic hazards. Since, the best rheology for modeling mass flows from volcanic activity is difficult to determine a number of rheologies have been proposed. These include the single phase Mohr-Coulomb models, Voellmy-Salm and Pouliquen-Forterre models or the more complicated two-phase models of Pitman-Le. We will discuss an approach based on using our newly released TITAN2D v4.0 (vhub.org) which allows seamless access to all four options for the same site in the same computational workflow. We introduce the use of simple Bayesian model averaging for hazard analysis based on an identified quantity of interest. In the second part of the presentation we will discuss the use of coupled models - a situation needed by the sequence of eruption, plume development and transport that must be understood for analyzing the hazards from volcanic ash transport. Both of these problems will be embedded in an UQ framework that attempts to quantify the probabilities of specific hazard criteria being met.31 14 - PublicationOpen AccessValidation data for manuscript "Novel statistical emulator construction for volcanic ash transport model Ash3d with physically-motivated measures"This database presents the testing and validation data used and presented in the manuscript titled "Novel statistical emulator construction for volcanic ash transport model Ash3d with physically-motivated measures". The manuscript is submitted to the Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. Please refer to the readme file for more details of the data.
54 6 - PublicationOpen AccessProbabilistic forecasting of plausible debris flows from Nevado de Colima (Mexico) using data from the Atenquique debris flow, 1955We detail a new prediction-oriented procedure aimed at volcanic hazard assessment based on geophysical mass flow models constrained with heterogeneous and poorly defined data. Our method relies on an itemized application of the empirical falsification principle over an arbitrarily wide envelope of possible input conditions. We thus provide a first step towards a objective and partially automated experimental design construction. In particular, instead of fully calibrating model inputs on past observations, we create and explore more general requirements of consistency, and then we separately use each piece of empirical data to remove those input values that are not compatible with it. Hence, partial solutions are defined to the inverse problem. This has several advantages compared to a traditionally posed inverse problem: (i) the potentially nonempty inverse images of partial solutions of multiple possible forward models characterize the solutions to the inverse problem; (ii) the partial solutions can provide hazard estimates under weaker constraints, potentially including extreme cases that are important for hazard analysis; (iii) if multiple models are applicable, specific performance scores against each piece of empirical information can be calculated. We apply our procedure to the case study of the Atenquique volcaniclastic debris flow, which occurred on the flanks of Nevado de Colima volcano (Mexico), 1955.We adopt and compare three depthaveraged models currently implemented in the TITAN2D solver, available from https://vhub.org (Version 4.0.0 – last access: 23 June 2016). The associated inverse problem is not well-posed if approached in a traditional way. We show that our procedure can extract valuable information for hazard assessment, allowing the exploration of the impact of synthetic flows that are similar to those that occurred in the past but different in plausible ways. The implementation of multiple models is thus a crucial aspect of our approach, as they can allow the covering of other plausible flows. We also observe that model selection is inherently linked to the inversion problem.
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