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  • 1
    Online Resource
    Online Resource
    San Diego :Elsevier,
    Keywords: Volcanic hazard analysis. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (533 pages)
    Edition: 1st ed.
    ISBN: 9780123964762
    Language: English
    Note: Front Cover -- Volcanic Hazards, Risks, and Disasters -- Copyright -- Contents -- Co-editors -- Contributors -- Editorial Foreword -- Introduction -- Chapter 1 - Global Distribution of Active Volcanoes -- 1.1 INTRODUCTION -- 1.2 PATTERNS IN GLOBAL VOLCANISM AND THEIR ASSOCIATED HAZARDS -- 1.3 POPULATIONS PROXIMAL TO VOLCANISM -- 1.4 PATTERNS IN VOLCANO-RELATED FATALITIES -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 2 - Basaltic Lava Flow Hazard -- 2.1 INTRODUCTION -- 2.2 WHAT MAKES A LAVA FLOW HAZARDOUS? -- 2.3 IMPACTS -- 2.4 MITIGATION -- 2.5 CONCLUSIONS -- REFERENCES -- Chapter 3 - Impacts from Volcanic Ash Fall -- DEFINITIONS USED IN THIS CHAPTER (MODIFIED FROM UN, 2009): -- 3.1 INTRODUCTION -- 3.2 ASH FALL CHARACTERISTICS AND HOW THEY INFLUENCE IMPACTS -- 3.3 VOLCANIC ASH IMPACT: SPATIAL AND TEMPORAL DIMENSIONS -- 3.4 QUANTIFYING VULNERABILITY TO ASH FALL -- 3.5 MITIGATING ASH FALL IMPACTS -- 3.6 MOVING FORWARD -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 4 - Volcanic Ash Hazards and Aviation Risk -- 4.1 INTRODUCTION -- 4.2 A VOLCANOLOGICAL AND METEOROLOGICAL HAZARD -- 4.3 DEVELOPMENT OF A GLOBAL FRAMEWORK TO AVOID ASH CLOUDS -- 4.4 EYJAFJALLAJÖKULL SHIFTS PERCEPTION OF RISKS AND GALVANIZES EFFORTS TO QUANTIFY HAZARDS -- 4.5 CONCLUSIONS -- REFERENCES -- Chapter 5 - Pyroclastic Density Current Hazards and Risk -- 5.1 INTRODUCTION -- 5.2 PDC GENERATION AND DYNAMICS -- 5.3 HAZARDOUS BEHAVIORS OF PDCS -- 5.4 HAZARD SCENARIOS AND PROBABILISTIC HAZARD ASSESSMENT -- 5.5 CONCLUDING REMARKS -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 6 - Lahars at Cotopaxi and Tungurahua Volcanoes, Ecuador: Highlights from Stratigraphy and Observational Records an ... -- 6.1 INTRODUCTION -- 6.2 TERMINOLOGY AND FUNDAMENTALS OF LAHAR GENERATION -- 6.3 PRIMARY LAHARS AND THEIR GENERATION AT COTOPAXI. , 6.4 THE FEBRUARY 12, 2005 RAIN-GENERATED LAHAR IN THE RÍO VAZCÚN CANYON, BAÑOS -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 7 - In situ Volcano Monitoring: Present and Future -- 7.1 INTRODUCTION -- 7.2 GROUND DEFORMATION -- 7.3 GRAVITY OBSERVATIONS -- 7.4 IN SITU MONITORING OF VOLCANIC GASES -- 7.5 SEISMOLOGICAL OBSERVATIONS -- 7.6 INFRASONIC -- 7.7 CONCLUSIONS -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 8 - Using Multiple Data Sets to Populate Probabilistic Volcanic Event Trees -- 8.1 INTRODUCTION -- 8.2 PROBABILISTIC VERSUS DETERMINISTIC FORECASTS -- 8.3 CONCEPT OF THE VOLCANIC EVENT TREE -- 8.4 HOW CAN PROBABILITIES BE ESTIMATED AT EACH NODE AND BRANCH OF A VOLCANIC EVENT TREE? -- 8.5 A HANDY EXCEL-BASED TOOL FOR BUILDING YOUR OWN TREE -- 8.6 IMPORTANCE OF DOCUMENTING THE BASIS FOR ALL PROBABILITY ESTIMATES -- 8.7 REMOTE PARTICIPATION IN DEVELOPMENT OF PROBABILITY TREES -- 8.8 APPLICATIONS OF THE MULTIPLE DATA SETS METHOD, BY VDAP AND OTHERS -- 8.9 APPLICATIONS OF PROBABILISTIC VOLCANIC EVENT TREES -- 8.10 PUBLIC PRESENTATION OF PROBABILISTIC EVENT TREES? -- 8.11 FUTURE IMPROVEMENTS -- REFERENCES -- Chapter 9 - Operational Short-term Volcanic Hazard Analysis: Methods and Perspectives -- 9.1 INTRODUCTION -- 9.2 THE BRADYSEISMIC CRISES AT CAMPI FLEGREI IN 1982-1984 -- 9.3 SHORT-TERM BET_VH SETTING FOR CAMPI FLEGREI -- 9.4 OPERATIONAL SHORT-TERM PVHA: THE ROLE OF REAL-TIME MONITORING DATA IN BET_VH -- 9.5 OPERATIONAL SHORT-TERM PVHA: RESULTS -- 9.6 FINAL REMARKS -- REFERENCES -- Chapter 10 - Human and Structural Vulnerability to Volcanic Processes -- 10.1 INTRODUCTION -- 10.2 HUMAN VULNERABILITY AND BUILDINGS -- 10.3 BUILDING VULNERABILITY IN MAIN VOLCANIC PROCESSES -- REFERENCES -- Chapter 11 - Cost-Benefit Analysis in Volcanic Risk -- 11.1 ASSESSING CRISIS MANAGEMENT STRATEGIES -- 11.2 THE ROOTS OF VALUE-BASED DECISION-MAKING. , 11.3 THE APPLICATION OF CBA -- 11.4 INTERFACE BETWEEN VOLCANOLOGISTS AND DECISION-MAKERS -- 11.5 CONCLUSION -- REFERENCES -- Chapter 12 - Volcanic Risks and Insurance -- 12.1 INTRODUCTION -- 12.2 INSURED LOSSES FROM VOLCANIC ERUPTIONS -- 12.3 VOLCANIC ERUPTION-AN INSURABLE RISK? -- 12.4 PRACTICE AND PRINCIPLES -- 12.5 MANAGING THE INSURANCE RISK -- 12.6 RATING VOLCANIC ERUPTION RISK -- 12.7 VOLCANIC ERUPTIONS-AN UNDERESTIMATED RISK? -- 12.8 LOCAL EVENTS-CITIES AT RISK -- 12.9 GLOBAL EVENTS -- 12.10 CONCLUSION -- REFERENCES -- Chapter 13 - Extreme Volcanic Risks 1: Mexico City -- 13.1 MEXICO CITY AND THE METROPOLITAN ZONE OF THE VALLEY OF MEXICO -- 13.2 VOLCANIC HAZARD ASSESSMENTS FOR MC -- 13.3 POSSIBLE SOURCES FOR ASHFALL IN MC -- 13.4 A MULTISOURCE, PROBABILISTIC APPROACH FOR HAZARDS ASSESSMENT -- 13.5 LIVING WITH THE EVERLASTING POSSIBILITY OF THE FORMATION OF A NEW VOLCANO IN THE VICINITY OF MC: DEALING WITH FALSE ALARMS -- 13.6 FUTURE PERSPECTIVES -- 13.7 SUMMARY -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 14 - Extreme Volcanic Risks 2: Mount Fuji -- 14.1 INTRODUCTION -- 14.2 CHARACTERISTICS OF FUJI VOLCANO -- 14.3 ERUPTIVE HISTORY OF FUJI VOLCANO -- 14.4 GEOPHYSICAL MONITORING -- 14.5 SECTOR COLLAPSE OF FUJI VOLCANO -- 14.6 ASHFALL DAMAGE ON ELECTRICITY IN THE TOKYO METROPOLITAN AREA -- 14.7 CONCLUSION -- REFERENCES -- Chapter 15 - Volcanic Gas and Aerosol Hazards from a Future Laki-Type Eruption in Iceland -- 15.1 INTRODUCTION -- 15.2 THE AD 1783-1784 LAKI ERUPTION -- 15.3 FREQUENCY OF ICELANDIC ERUPTIONS AND LIKELIHOOD OF A LAKI-TYPE ERUPTION -- 15.4 VOLCANIC GAS AND AEROSOL HAZARDS FROM A FUTURE LAKI-TYPE ERUPTION -- 15.5 DISCUSSION -- 15.6 SUMMARY -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 16 - Explosive Super-Eruptions and Potential Global Impacts -- 16.1 INTRODUCTION -- 16.2 SUPERSIZED ERUPTIONS -- 16.3 THE NEXT SUPER-ERUPTION?. , 16.4 PRODUCTS OF SUPER-ERUPTIONS -- 16.5 EFFECTS OF SUPER-ERUPTIONS -- 16.6 SOCIETAL IMPACTS OF SUPER-ERUPTIONS -- 16.7 SUMMARY AND FUTURE CONCERNS -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 17 - Integration of European Volcano Infrastructures -- 17.1 RATIONALE -- 17.2 STATE OF THE ART OF THE EUROPEAN VOLCANOLOGICAL RIS -- 17.3 GAP ANALYSIS AND SOCIAL OR SCIENTIFIC NEEDS -- 17.4 PRINCIPLES OF THE VOLCANO OBSERVATION RI -- 17.5 CURRENT INITIATIVES IN THE INTEGRATION OF EUROPEAN VOLCANO RIS -- 17.6 POSSIBLE IMPLEMENTATION AND FUTURE EVOLUTIONS -- 17.7 CONCLUDING REMARKS -- ACKNOWLEDGMENTS -- REFERENCES -- Chapter 18 - Integrated Monitoring of Japanese Volcanoes -- 18.1 INTRODUCTION -- 18.2 TARGET VOLCANOES FOR MONITORING -- 18.3 MONITORING VOLCANOES -- 18.4 OBSERVATIONAL RESEARCH BY THE NATIONAL UNIVERSITIES AND OTHER RESEARCH INSTITUTES -- 18.5 INTEGRATED MONITORING OF VOLCANOES IN JAPAN -- 18.6 ROLE OF THE CCPVE IN THE INTEGRATED MONITORING OF VOLCANOES -- 18.7 PERSPECTIVES -- ACKNOWLEDGMENT -- REFERENCES -- Chapter 19 - Integrating Efforts in Latin America: Asociación Latinoamericana de Volcanología (ALVO) -- 19.1 VOLCANISM IN LATIN AMERICA -- 19.2 HISTORICAL DEVELOPMENT OF THE LATIN AMERICAN ASSOCIATION OF VOLCANOLOGY -- 19.3 ALVO FIRST STEPS -- 19.4 A CRITICAL VIEW INTO THE SWOT FOR THE DEVELOPMENT OF VOLCANOLOGY IN THE LATIN AMERICAN REGION -- 19.5 FUTURE PERSPECTIVES -- 19.6 SUMMARY -- ACKNOWLEDGMENTS -- REFERENCES -- Index.
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  • 2
    Online Resource
    Online Resource
    San Diego :Elsevier,
    Keywords: Volcanic activity prediction. ; Emergency management. ; Volcanic eruptions. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (710 pages)
    Edition: 1st ed.
    ISBN: 9780128180839
    DDC: 551.21
    Language: English
    Note: Intro -- Forecasting and Planning for Volcanic Hazards, Risks, and Disasters -- Copyright -- Contents -- Contributors -- Preface -- Chapter 1: Some relevant issues in volcanic hazard forecasts and management of volcanic crisis -- 1. Introduction -- 2. Volcanoes as complex dynamic systems -- 3. Volcanic alert levels at high-risk volcanoes -- 4. Forecasting eruption size at reawakening volcanoes -- 5. Forecasting the impacted areas -- 6. Best practices -- 7. Global volcanic hazards -- Acknowledgments -- References -- Chapter 2: A review of seismic methods for monitoring and understanding active volcanoes -- 1. Introduction -- 2. Seismic sources and related signals -- 2.1. High-frequency events -- 2.2. Long-period events -- 2.3. Volcanic tremor -- 2.4. Very-long period events -- 2.5. Explosions and other volcanic signals -- 3. Seismic monitoring -- 3.1. Instrumentation for recording of seismicity -- 3.1.1. Distributed acoustic sensing -- 3.1.2. Rotational sensors -- 3.2. Signal detection -- 3.3. Classification -- 3.4. Location -- 3.4.1. Coherence-based methods -- 3.4.2. Back-propagation methods -- 3.4.3. Amplitude-based methods -- 3.4.4. Time-reverse location methods -- 3.4.5. Array methods -- 4. Methods for source studies -- 4.1. Remarks on moment-tensor inversion of volcanic LP and VLP sources -- 5. Subsurface investigation -- 5.1. Seismic tomography from earthquakes and active sources -- 5.2. Shallow velocity structures from surface wave dispersion -- 5.3. Ambient noise tomography -- 5.4. Temporal changes of medium properties -- 6. Conclusions and future opportunities -- Acknowledgments -- References -- Chapter 3: Volcano geodesy: A critical tool for assessing the state of volcanoes and their potential for hazardous erupti ... -- 1. The ups and downs of volcanoes -- 2. Measuring deformation and gravity change -- 2.1. ``Classic´´ volcano geodesy. , 2.2. ``Modern´´ volcano geodesy -- 3. Forecasting volcanic activity with geodesy -- 3.1. Eruption onset -- 3.2. Eruption evolution -- 3.3. Forecasting challenges -- 4. Limitations of geodetic data -- 4.1. Data collection -- 4.2. Data interpretation -- 5. Beyond the subsurface: Novel uses of geodetic data -- 5.1. Surface change -- 5.2. Detection and characterization of volcanic plumes -- 5.3. Properties of magma and magmatic systems -- 6. Case studies -- 6.1. Agung, Indonesia: Geodetic insights into pre- and co-eruptive volcanic activity and hazards -- 6.2. Saba and St. Eustatius, Dutch Antilles: Preemptive geodetic response at historically dormant volcanic islands -- 7. The future of geodesy applied to volcanic hazards -- Acknowledgments -- References -- Chapter 4: Geochemical monitoring of volcanoes and the mitigation of volcanic gas hazards -- 1. Introduction -- 1.1. Magmatic degassing and the tenet of geochemical monitoring -- 2. Measurements of fumarolic/vent emissions, volcanic plumes, soil gases, and springs -- 2.1. High-temperature gases from fumaroles and active vents -- 2.2. Low temperature, hydrothermal emissions -- 2.3. Stable isotopes and noble gases -- 2.4. Gas flux measured in volcanic plumes and clouds -- 2.5. Soil gas monitoring -- 3. Volcanic gas hazard and risk -- 4. Limits to knowledge and future developments -- References -- Chapter 5: A review of the physical and mechanical properties of volcanic rocks and magmas in the brittle and ductile regimes -- 1. Introduction -- 2. Physical properties of volcanic materials -- 2.1. The porosity of volcanic rocks and magmas -- 2.2. Permeable pathways in volcanic rocks and magmas -- 2.3. Ultrasonic velocity in volcanic materials -- 3. Thermo-mechanical properties of volcanic rocks -- 3.1. The mechanical properties of volcanic rocks under unconfined conditions. , 3.2. The mechanical properties of volcanic rocks under confined conditions -- 3.3. Thermal expansivity, thermal stressing, and thermal microcracking -- 3.4. Thermal-sensitivity of mineralogical assemblages: the importance of secondary mineralization and devolatilization re ... -- 3.5. Mechanical properties of volcanic rocks at elevated temperature -- 4. The rheology of magmas -- 4.1. Silicate melt rheology: Viscosity and the glass transition -- 4.2. Multiphase magma viscosity -- 4.3. Crystal plasticity in magmas -- 4.4. The strength of multiphase magmas -- 4.5. Magmatic fragmentation -- 4.6. Criteria for multiphase magma failure -- 5. Material rupture architecture and seismogenicity -- 6. Tribological and frictional properties of volcanic materials -- 7. Concluding remarks -- Acknowledgments -- References -- Chapter 6: Numerical modeling of magma ascent dynamics -- 1. Introduction -- 2. Conduit models -- 3. Case studies -- 3.1. Mechanical disequilibrium/outgassing -- 3.2. Conduit geometry -- 3.3. Temperature -- 3.4. Phreatomagmatic interaction -- 4. Conclusions -- Appendix A -- Acknowledgments -- References -- Chapter 7: Understanding volcanic systems and their dynamics combining field and physical volcanology with petrology studies -- 1. Introduction -- 2. Reconstructing the evolution of a volcanic system -- 2.1. Geological mapping and stratigraphic studies -- 2.2. Geochronological studies -- 2.3. Physical characterization of eruptions -- 2.4. Petrology and geochemistry of erupted products -- 3. Studying single-eruption sequences -- 3.1. Sampling strategies for pyroclastic deposits -- 3.2. Componentry of pyroclastic deposits -- 3.3. Internal variability in the products of an effusive eruption -- 4. Petrological constraints to magma genesis and evolution -- 4.1. The nature and composition of the magma source. , 4.2. Defining physical and chemical parameters of magmatic processes -- 4.3. Dynamics of magmatic processes -- 4.4. Timescales for magma crystallization and degassing -- 5. Experimental constraints on volcano evolution and eruption dynamics -- 5.1. P-T conditions of magma evolution: Phase equilibrium studies -- 5.2. Constraints to magma degassing: Volatile solubilities -- 5.3. Experimental constraints to magma mixing/interaction -- 5.4. Constraints to the rates of magma ascent: Decompression experiments -- 5.5. Measuring physical properties of rocks and magmas -- 6. Discussion and conclusions -- References -- Chapter 8: Assessment of risk associated with tephra-related hazards -- 1. Introduction -- 2. Tephra dispersal, fallout and aeolian ash remobilization -- 3. Impacts associated with tephra fallout, dispersal, and aeolian ash remobilization -- 4. Hazard assessment -- 5. Exposure and vulnerability assessment -- 5.1. Physical vulnerability -- 5.2. Socio-economic vulnerability -- 5.3. Systemic vulnerability -- 6. Risk assessment -- 6.1. Risk assessment at local scale based on in-situ vulnerability analysis -- 6.2. Exposure-based risk assessment at regional scale -- 6.3. Exposure-based risk assessment at continental scale for tephra dispersal -- 7. Discussion and conclusions -- 7.1.1. Recent developments in hazard and vulnerability assessment of tephra-related phenomena -- 7.1.2. Current challenges of risk assessment -- Acknowledgments -- References -- Chapter 9: The dynamics of explosive mafic eruptions: New insights from multiparametric observations -- 1. Introduction -- 2. Volcano monitoring techniques: Acquisition rates, modes, and strategies -- 2.1. FAMoUS: A Fast, Multiparametric Setup for studying explosive volcanic activity -- 3. Key eruptive processes: Insights from multiparametric measurements. , 3.1. The ejection of pyroclasts at the vent: Ejection velocity and ejection pulses -- 3.2. Features and dynamics of eruptive supersonic jets from mafic explosive eruptions -- 3.3. The growth of eruption plumes from pulsatory, mafic explosive activity -- 3.4. Volcanic ballistics projectiles -- 3.5. Vent dynamics and their influence on eruption style -- 3.6. Towards a more quantitative definition of eruptive styles -- 4. Final considerations -- 4.1. Technological advancements -- 4.2. Volcanological perspectives -- Acknowledgments -- References -- Chapter 10: Recent basaltic eruptions in Iceland and the dynamics of co-eruptive subsurface magma flow -- 1. Introduction -- 2. Volcanism in Iceland -- 3. A mathematical model for magma flow in basaltic eruptions -- 4. Eyjafjallajökull flank (Fimmvöruháls) eruption 2010 -- 5. Grímsvötn 2011 eruption -- 6. Bárarbunga 2014-2015 -- 7. Discussion -- 8. Conclusions -- Acknowledgments -- References -- Chapter 11: Volcanic lake dynamics and related hazards -- 1. Introduction -- 1.1. The early history of volcanic lake research -- 1.2. Classification of volcanic lakes -- 2. Mechanisms leading to hazardous events -- 2.1. From sealing to phreatic eruptions -- 2.2. Gas hazards and limnic gas burst revisited -- 2.2.1. Direct gas emissions -- 2.2.2. Gas beracun at hyperacidic lakes: The Kawah Ijen case -- 2.2.3. Degassing of geothermally heated caldera lakes and medium activity lakes -- 2.2.4. Nyos-type vs anti-Nyos-type vs bioactivity lakes -- 2.3. The sudden release of water: Floods and lahars -- 3. Impacts and risk perception -- 3.1. In modern times -- 3.2. Sociocultural views and aspects -- 4. Monitoring and mitigation strategies -- 5. Conclusive remarks -- Acknowledgments -- References -- Chapter 12: Remote sensing of volcanic impacts -- 1. Introduction -- 2. Remote sensing for volcanic impact assessment. , 2.1. Preevent impact assessments.
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 397 (1999), S. 425-428 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Explosive eruptions are the most powerful and destructive type of volcanic activity. These eruptions are characterized by magma fragmentation, the process through which a bubbly or foamy magma is transformed into a gas–pyroclast dispersion. Although magma fragmentation has been ...
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of volcanology 55 (1993), S. 523-535 
    ISSN: 1432-0819
    Keywords: Ecuadorian volcanism ; explosive eruptions ; plinian fallout ; plinian column ; clast dispersal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The caldera of Pululagua is an eruptive centre of the Northern Volcanic Zone of the South American volcanic arc, located about 15 km north of Quito, Ecuador. Activity leading to formation of the caldera occurred about 2450 b.p. as a series of volcanic episodes during which an estimated 5–6 km3 (DRE) of hornblende-bearing dacitic magma was erupted. A basal pumice-fall deposit covers more than 2.2x104 km2 with a volume of about 1.1 km3 and represents the principal and best-preserved plinian layer. Circular patterns of isopachs and pumice, lithic and Md isopleths of the Basal Fallout (BF) around the caldera indicate emplacement in wind-free conditions. Absence of wind is confirmed by an ubiquitous, normally graded, thin ash bed at the top of the lapilli layer which originated from slow settling of fines after cessation of the plinian column (co-plinian ash). The unusual atmospheric conditions during deposition make the BF deposit particularly suitable for the application and evaluation of pyroclast dispersal models. Application of the Carey and Sparks' (1986) model shows that whereas the 3.2-, 1.6-, and 0.8-cm lithic isopleths predict a model column height of about 36 km, the 6.4-cm isopleth yields and estimate of only 21 km. The 4.9- and 6.4-cm isopleths yield a column height of 28 km using the model of Wilson and Walker (1987). The two models give the same mass discharge rate of 2x108 kg s-1. A simple exponential decrease of thickness with distance, as proposed by Pyle (1989) for plinian falls, fits well with the BF. Exponential decrease of size with distance is followed by clasts less than about 3 cm, suggesting, in agreement with Wilson and Walker (1987), that only a small proportion of large clasts reach the top of the column. Variations with distance in clast distribution patterns imply that, in order to obtain column heights by clast dispersal models, the distribution should be known from both proximal and distal zones. Knowledge of only a few isopleths, irrespective of their distance from the vent, is not sufficient as seemed justified by the method of Pyle (1989).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of volcanology 60 (1999), S. 583-594 
    ISSN: 1432-0819
    Keywords: Key words Carbon dioxide ; Magma ascent ; Explosive eruptions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The role of carbon dioxide in the dynamics of magma ascent in explosive eruptions is investigated by means of numerical modeling. The model is steady, one-dimensional, and isothermal; it calculates the separated flow of gas and a homogeneous mixture of liquid magma and crystals. The magma properties are calculated on the basis of magma composition and crystal content and are allowed to change along the conduit due to pressure decrease and gas exsolution. The effect of the presence of a two-component (water + carbon dioxide) exsolving gas phase is investigated by performing a parametric study on the CO2/(H2O+CO2) ratio, which is allowed to vary from 0 to 0.5 at either constant total volatile or constant water content. The relatively insoluble carbon dioxide component plays an important role in the location of the volatile-saturation and magma-fragmentation levels and in the distribution of the flow variables in the volcanic conduit. In detail, the results show that an increase of the proportion of carbon dioxide produces a decrease of the mass flow rate, pressure, and exit mixture density, and an increase of the exit gas volume fraction and depth of the fragmentation level. A relevant result is the different role played by water and carbon dioxide in the eruption dynamics; an increasing amount of water produces an increase of the mass flow rate, and an increasing amount of carbon dioxide produces a decrease. Even small amounts of carbon dioxide have major consequences on the eruption dynamics, implying that the multicomponent nature of the volcanic gas must be taken into account in the prediction of the eruption scenario and the forecasting of volcanic hazard.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 126 (1997), S. 237-251 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The modeling of the solubility of water and carbon dioxide in silicate liquids (flash problem) is performed by assuming mechanical, thermal, and chemical equilibrium between the liquid magma and the gas phase. The liquid phase is treated as a mixture of ten silicate components + H2O or CO2, and the gas phase as a pure H2O or CO2. A general model for the solubility of a volatile component in a liquid is adopted. This requires the definition of a mixing equation for the excess Gibbs free energy of the liquid phase and an appropriate reference state for the dissolved volatile. To constrain the model parameters and identify the most appropriate form of the solubility equations for each dissolved volatile, a large number of experimental solubility determinations (640 for H2O and 263 for CO2) have been used. These determinations cover a large region of the P-T-composition space of interest. The resultant water and carbon dioxide solubility models differ in that the water model is regular and isometric, and the carbon dioxide model is regular and non-isometric. This difference is consistent with the different speciation modalities of the two volatiles in the silicate liquids, producing a composition-independent partial molar volume of dissolved water and a composition-dependent partial molar volume of dissolved carbon dioxide. The H2O solubility model may be applied to natural magmas of virtually any composition in the P-T range 0.1 MPa–1 GPa and 〉 1000 K, whereas the CO2 solubility model may be applied to several GPa pressures. The general consistency of the water solubility data and their relatively large number as compared to the calibrated model parameters (11) contrast with the large inconsistencies of the carbon dioxide solubility determinations and their low number with respect to the CO2 model parameters (22). As a result, most of the solubility data in the database are reproduced within 10% of approximation in the case of water, and 30% in the case of carbon dioxide. When compared with the experimental data, the H2O and CO2 solubility models correctly predict many features of the saturation surface in the P-T-composition space, including the change from retrograde to prograde H2O solubility in albitic liquids with increasing pressure, the so-called alkali effect, the increasing CO2 solubility with increasing degree of silica undersaturation, the Henrian behavior of CO2 in most silicate liquids up to about 30–50 MPa, and the proportionality between the fugacity in the gas phase, or the saturation activity in the liquid phase, and the square of the mole fraction of the dissolved volatile found in some unrelated silicate liquid compositions.
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  • 7
    Publication Date: 2020-11-20
    Description: Rhyolite and felsite cuttings were collected at Krafla volcano during the perforation of the Iceland Deep Drilling Project Well 1 (IDDP-1). The perforation was stopped at a depth of 2100m due to intersection with a rhyolite magma that intruded the felsite host rock. Rhyolite cuttings are vitrophiric (glass ~95%, RHL) and exhibit a mineral assemblage made of plagioclase+augite+pigeonite+titanomagnetite. Felsite cuttings display evidences of partial melting, responding to variable degrees of quartz+plagioclase+alkali feldspar+augite+ titanomagnetite dissolution. The interstitial glass analyzed close to (i.e., FLS1) and far from (i.e., FLS2) the reaction surface of pyroxene from felsite cuttings shows continuous changes between the two end-members. FLS1 is compositionally similar to RHL, showing Na2O+K2O+REE depletions, counterbalanced by MgO+CaO enrichments. Conversely, FLS2 exhibits opposite chemical features. REE-exchange thermobarometric calculations reveal that plagioclase and augite cores from rhyolite and felsite formed under identical conditions, along a thermal path of 940–960 °C. However, in terms of major and trace element concentrations, plagioclase and augite crystal cores are not in equilibrium with the rhyolite magma, suggesting the incorporation of these minerals directly from the host felsite. To better understand the petrogenetic relationship between rhyolite and felsite, two sets of crystallization and partial melting experiments have been carried out at P=150 MPa and T=700–950 °C. Rhyolite crystallization experiments (RCE) reproduce the two-pyroxene assemblage of IDDP-1 rhyolite cuttings only at T≤800 °C, when the crystal content (≥19%) is higher than that observed in the natural rhyolite (~5%). Under such conditions, the RCE glass is much more differentiated (i.e., marked CaO depletion and Eu anomaly) than RHL. On the other hand, felsite partial melting (FPM) experiments show interstitial glass with a bimodal composition (i.e., FPM1 and FPM2) comparable to FLS1 (≈RHL) and to FLS2, only at T=950 °C. This effect has been quantified by fractional crystallization and batch melting modeling, denoting that FLS1 (≈RHL) and FLS2 reflect high (≥70%) and low (≤8%) degrees of felsite partialmelting, respectively. In contrast, modeling RHL by crystal fractionation requires the removal of an amount (~22%) of solid material that is inconsistent with the low crystal content of the natural IDDP-1 rhyolite. It is therefore concluded that natural rhyolite and felsite represent, respectively, the near-liquidus and sub-solidus states of a virtually identical silicic magma, either feeding aphyric to subaphiric rhyolitic eruptions, or solidifying at depth as phaneritic quartzofeldspathic rocks. Felsite lenses from the Krafla substrate may explore variable degrees of remelting and remobilization processes. The intrusion into felsite of a fresh silicic magma from depth may lead to low degrees of partial melting, whereas the persistent heat release from intense basaltic intrusive events at Krafla may be the source of high degrees of felsite partial melting and consequent rejuvenation of the previously solidified silicic magma.
    Description: Published
    Description: 603-618
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2021-01-07
    Description: Reducing the impact of volcanic eruptions on society is a major challenge of volcanology. Although science is one basic component of risk reduction, the achievement of this goal requires competencies that go beyond natural sciences. Nowadays, the importance of non-scientific factors in reducing volcanic risks is often and dangerously overlooked, possibly leading to decision making that cannot be rationally justified. In this paper we explore the basic components of an ideal decision-making process, identifying the roles and responsibilities of the different partners/tasks that are involved. In particular, we advocate the use of the hazard/risk separation principle, which can help discern unambiguously the role of volcanology (and more in general of science) in the whole risk-reduction process. Although this distinction may be of low relevance in some real cases—for example, when the costs of mitigation actions are low and the likelihood of eruption is high—it becomes of paramount importance when dealing with high uncertainty on the eruption onset or size and expensive mitigation actions, such as the evacuation of a large city. Volcanologists can play different roles in the decision-making process, but they have to be aware that this demands competencies that go beyond being a good volcano scientist. The final intent of this paper is to encourage constructive cooperation between volcanologists and public-policy makers keeping separated their own tasks as defined by their roles and their competences, with the intent of establishing fully transparent decision-making protocols well before volcanic crises. These protocols can be very helpful to audit the decision-making process at any time, and they may be an excellent communication tool for the interested stakeholders, including society.
    Description: Published
    Description: 545-564
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 9
    Publication Date: 2020-11-09
    Description: EUROVOLC Virtual Accesses offer the opportunity to anyone with a web access to use online tools related to volcanological research. The Volcano Dynamics Computational Center at INGV in Pisa offers the access to a suite of fast-performing numerical codes aimed at modeling different aspects of volcano dynamics: solwcad: Fortran code that computes the fully non-ideal, multi-component, compositional-dependent saturation surface of H2O+CO2 in silicate melts over P-T-composition conditions relevant to magmatism and volcanism. Calculations allow to either 1) determine the partition of H2O and CO2 between the melt and gas phase, or 2) determine the entrapment pressure and corresponding gas phase composition from dissolved amounts; MAMMA: FORTRAN90 code designed to solve a conservative model for magma ascent in a volcanic conduit, described as a compressible multi-component two-phase flow. The system of conservation equations considers the effects of the main processes that magmas experience during ascent, such as crystallization, rheological changes, fragmentation, physical interaction with conduit walls, out-gassing and degassing. The model is capable of describing conduits with elliptical cross sections and depth-dependent dimensions; PyBOX: Python/Fortran90 code that solves the so-called “box model” equations describing the kinematics of a pyroclastic density current over a flat surface and in a steady atmosphere. The model integrates a procedure to account for blockage of PDCs by a rugged topography imported as a ASCII file, by adopting the so-called “energy-conoid” approach. Virtual Access will include an interface to import the DEM file and input parameters and to visualize georeferenced maps of invasion and plots of decaying dynamic pressure.
    Description: Unpublished
    Description: Catania
    Description: 5V. Processi eruttivi e post-eruttivi
    Keywords: numerical models ; vulcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 10
    Publication Date: 2021-05-12
    Description: Persistent degassing of closed-conduit explosive volcanoes may be used to inspect and monitor magmatic processes. After interaction with shallow hydrothermal fluids, volcanic gases collected at surface can differ substantially from those exsolved from magma. We report here on an innovative approach to identify and separate the contribution of variable magmatic components from fumarolic gases, by processing the 30-year-long geochemical dataset from the Campi Flegrei caldera, Southern Italy. The geochemical record shows periodic variations, which are well correlated with geophysical signals. Such variations are interpreted as due to the time-varying interplay of two magma degassing sources, each differing in size, depth, composition, and cooling/crystallization histories. Similar multiple degassing sources are common at explosive volcanoes, with frequent ascent and intrusion of small magma batches. Our innovative method permits the identification of those magma batches, which contributes to the interpretation of unrest signals, forecasting and assessment of volcanic hazards
    Description: Published
    Description: 95-104
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: magmatic degassing ; hydrothermal systems ; explosive volcanism ; isotopic inversion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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