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  • 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis  (6)
  • 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
  • Springer Science+Business Media B.V.  (4)
  • Springer Berlin / Heidelberg  (3)
  • American Physical Society
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Keywords
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  • 1
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    Buoyancy Effects on Upward Brine Displacement Caused by CO2 Injection (2012)
    Springer Science+Business Media B.V.
    Details
    Publication Date: 2020-02-24
    Description: Upward displacement of brine from deep reservoirs driven by pressure increases resulting fromCO2 injection for geologic carbon sequestrationmay occur through improperly sealed abandoned wells, through permeable faults, or through permeable channels between pinch-outs of shale formations. The concern about upward brine flow is that, upon intrusion into aquifers containing groundwater resources, the brinemay degrade groundwater. Because both salinity and temperature increase with depth in sedimentary basins, upward displacement of brine involves lifting fluid that is saline but also warm into shallower regions that contain fresher, cooler water. We have carried out dynamic simulations using TOUGH2/EOS7 of upward displacement of warm, salty water into cooler, fresher aquifers in a highly idealized two-dimensional model consisting of a vertical conduit (representing a well or permeable fault) connecting a deep and a shallow reservoir. Our simulations show that for small pressure increases and/or high-salinity-gradient cases, brine is pushed up the conduit to a new static steady-state equilibrium. On the other hand, if the pressure rise is large enough that brine is pushed up the conduit and into the overlying upper aquifer, flow may be sustained if the dense brine is allowed to spread laterally. In this scenario, dense brine only contacts the lower-most region of the upper aquifer. In a hypothetical case in which strong cooling of the dense brine occurs in the upper reservoir, the brine becomes sufficiently dense that it flows back down into the deeper reservoir from where it came. The brine then heats again in the lower aquifer and moves back up the conduit to repeat the cycle. Parameter studies delineate steady-state (static) and oscillatory solutions and reveal the character and period of oscillatory solutions. Such oscillatory solutions aremostly a curiosity rather than an expected natural phenomenon because in nature the geothermal gradient prevents the cooling in the upper aquifer that occurs in the model. The expected effect of upward brine displacement is either establishment of a new hydrostatic equilibrium or sustained upward flux into the bottom-most region of the upper aquifer.
    Description: Published
    Description: 525-540
    Description: JCR Journal
    Description: restricted
    Keywords: Geologic carbon sequestration ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Basic principles of multi-risk assessment: a case study in Italy (2012)
    Springer Science+Business Media B.V.
    Details
    Publication Date: 2020-02-05
    Description: 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.
    Description: FP6 European project NaRaS; FP7 European project MATRIX
    Description: Published
    Description: 551-573
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: restricted
    Keywords: multi-risk assessment ; hazard interaction ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Analysis of self-organised criticality in the Olami-Feder-Christensen model and in real earthquakes (2007)
    American Physical Society
    Details
    Publication Date: 2017-04-04
    Description: We perform an analysis on the dissipative Olami-Feder-Christensen model on a small world topology considering avalanche size differences. We show that when criticality appears, the probability density functions (PDFs) for the avalanche size differences at different times have fat tails with a q-Gaussian shape. This behavior does not depend on the time interval adopted and is found also when considering energy differences between real earthquakes. Such a result can be analytically understood if the sizes (released energies) of the avalanches (earthquakes) have no correlations. Our findings support the hypothesis that a self-organized criticality mechanism with long-range interactions is at the origin of seismic events and indicate that it is not possible to predict the magnitude of the next earthquake knowing those of the previous ones.
    Description: Published
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: SOC, earthquakes interaction ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Dike propagation within active central volcanic edifices: constraints from Somma-Vesuvius, Etna and analogue models (2008)
    Springer Berlin / Heidelberg
    Details
    Publication Date: 2017-04-04
    Description: Dikes within stratovolcanoes are commonly expected to have radial patterns. However, other patterns may also be also found, due to regional stresses, magmatic reservoirs, topographic variations. Here we investigate dike patterns within volcanic edifices, by studying dike and fissure complexes at Somma-Vesuvius and Etna (Italy) and using analogue models. At the surface, the dikes and fissures show a radial configuration. At depths of tens to several hundreds of m, in areas exposed by erosion, tangential and oblique dikes are also present. Analogue models indicate that dikes approaching the flanks of cones, regardless of their initial orientation, reorient to become radial (parallel to the maximum gravitational stress). This reorientation is a significant process in shallow magma migration and may also control the emplacement of dike-fed fissures reaching the lower slopes of the volcano.
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: dike ; Etna ; Somma-Vesuvius ; analogue models ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Lava flow hazard at Nyiragongo volcano, D.R.C. 1. Model calibration and hazard mapping (2010)
    Springer Berlin / Heidelberg
    Details
    Publication Date: 2017-04-04
    Description: The 2002 eruption of Nyiragongo volcano constitutes the most outstanding case ever of lava flow in a big town. It also represents one of the very rare cases of direct casualties from lava flows, which had high velocities of up to tens of kilometer per hour. As in the 1977 eruption, which is the only other eccentric eruption of the volcano in more than 100 years, lava flows were emitted from several vents along a N–S system of fractures extending for more than 10 km, from which they propagated mostly towards Lake Kivu and Goma, a town of about 500,000 inhabitants. We assessed the lava flow hazard on the entire volcano and in the towns of Goma (D.R.C.) and Gisenyi (Rwanda) through numerical simulations of probable lava flow paths. Lava flow paths are computed based on the steepest descent principle, modified by stochastically perturbing the topography to take into account the capability of lava flows to override topographic obstacles, fill topographic depressions, and spread over the topography. Code calibration and the definition of the expected lava flow length and vent opening probability distributions were done based on the 1977 and 2002 eruptions. The final lava flow hazard map shows that the eastern sector of Goma devastated in 2002 represents the area of highest hazard on the flanks of the volcano. The second highest hazard sector in Goma is the area of propagation of the western lava flow in 2002. The town of Gisenyi is subject to moderate to high hazard due to its proximity to the alignment of fractures active in 1977 and 2002. In a companion paper (Chirico et al., Bull Volcanol, in this issue, 2008) we use numerical simulations to investigate the possibility of reducing lava flow hazard through the construction of protective barriers, and formulate a proposal for the future development of the town of Goma.
    Description: Published
    Description: 363-374
    Description: 2.1. TTC - Laboratorio per le reti informatiche, GRID e calcolo avanzato
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Lava flow ; Nyiragongo ; Volcanic hazard ; Numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Local geodetic and seismic energy balance for shallow earthquake prediction (2015)
    Springer Science+Business Media B.V.
    Details
    Publication Date: 2017-04-04
    Description: Earthquake analysis for prediction purposes is a delicate and still open problem largely debated among scientists. In this work, we want to show that a successful time-predictable model is possible if based on large instrumental data from dense monitoring networks. To this aim, we propose a new simple data-driven and quantitative methodology which takes into account the accumulated geodetic strain and the seismically-released strain to calculate a balance of energies. The proposed index quantifies the state of energy of the selected area and allows us to evaluate better the ingoing potential seismic risk, giving a new tool to read recurrence of small-scale and shallow earthquakes. In spite of its intrinsic simple formulation, the application of the methodology has been successfully simulated in the Eastern flank of Mt. Etna (Italy) by tuning it in the period 2007–2011 and testing it in the period 2012–2013, allowing us to predict, within days, the earthquakes with highest magnitude.
    Description: Published
    Description: 1-8
    Description: 1T. Geodinamica e interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake prediction ; Time-predictable model ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    BET_VH: exploring the influence of natural uncertainties on long-term hazard from tephra fallout at Campi Flegrei (Italy) (2010)
    Springer Berlin / Heidelberg
    Details
    Publication Date: 2017-04-04
    Description: In this paper, we explore the effects of the intrinsic uncertainties upon long-term volcanic hazard by analyzing tephra fall hazard at Campi Flegrei, Italy, using the BET_VH model described in Marzocchi et al. (Bull Volcanol, 2010). The results obtained show that volcanic hazard based on the weighted average of all possible eruptive settings (i.e. size classes and vent locations) is significantly different from an analysis based on a single reference setting, as commonly used in volcanic hazard practice. The long-term hazard map for tephra fall at Campi Flegrei obtained here accounts for a wide spectrum of uncertainties which are usually neglected, largely reducing the bias intrinsically introduced by the choice of a specific reference setting. We formally develop and apply a general method to recursively integrate simulations from different models which have different characteristics in terms of spatial coverage, resolution and physical details. This outcome of simulations will be eventually merged with field data through the use of the BET_VH model.
    Description: Published
    Description: 717-733
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: open
    Keywords: Volcanic hazard ; Ash fall · ; Bayesian event tree ; Campi Flegrei ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Scoring and Testing Procedures Devoted to Probabilistic Seismic Hazard Assessment (2015)
    Springer Science+Business Media B.V.
    Details
    Publication Date: 2017-04-04
    Description: This review addresses long-term (tens of years) seismic ground-motion forecasting (seismic hazard assessment) in the presence of alternative computational models (the so-called epistemic uncertainty affecting hazard estimates). We review the different approaches that have been proposed to manage epistemic uncertainty in the context of probabilistic seismic hazard assessment (PSHA). Ex-ante procedures (based on the combination of expert judgments about inherent characteristics of the PSHA model) and expost approaches (based on empirical comparison of model outcomes and observations) should not be considered as mutually exclusive alternatives but can be combined in a coherent Bayesian view. Therefore, we propose a procedure that allows a better exploitation of available PSHA models to obtain comprehensive estimates, which account for both epistemic and aleatory uncertainty. We also discuss the respective roles of empirical ex-post scoring and testing of alternative models concurring in the development of comprehensive hazard maps. In order to show how the proposed procedure may work, we also present a tentative application to the Italian area. In particular, four PSHA models are evaluated ex-post against macroseismic effects actually observed in a large set of Italian municipalities during the time span 1957–2006. This analysis shows that, when the whole Italian area is considered, all the models provide estimates that do not agree with the observations. However, two of them provide results that are compatible with observations, when a subregion of Italy (Apulia Region) is considered. By focusing on this area, we computed a comprehensive hazard curve for a single locality in order to show the feasibility of the proposed procedure.
    Description: Published
    Description: 269–293
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic hazard ; PSHA ; Testing ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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