Volume 4. From Magma to Tephra

1st Edition

Modelling Physical Processes of Explosive Volcanic Eruptions

Editors:

  • A. Freundt
  • M. Rosi
  • Description

    Hot magma rising through the Earth's crust releases gases that expand and may come into contact with external water that vaporizes. The magma is then fragmented into an accelerating gas-particle/droplet mixture that is shot into the atmosphere, possibly in an overpressured state, where it may buoyantly rise up into the stratosphere as an ash plume, partially or totally collapse back to the surface, or rapidly expand sideways, or undergo a combination of these processes. Tephra is then deposited on the Earth's surface by pyroclastic fall, flow or surge, or some hybrid mechanism. The combination of processes that operate from the degassing of magma to the emplacement of tephra makes an explosive volcanic eruption, and the physical characterization of these processes is the scope of this book.

    In this book we summarize the insights into key aspects of explosive volcanic eruptions gained from physical modelling to date.

    The seven chapters are arranged in an order reflecting the sequence from processes acting within the volcanic conduit through dynamics of eruption and transport through the atmosphere to mechanisms of emplacement on the Earth's surface.

    Chapter 1 reviews the progress made in understanding how magma vesiculates and fragments, considering results obtained by experiment, theory, and analysis of the vesicle-texture of pumice. Magmatic fragmentation is discussed in terms of brittle failure as tensile strength is exceeded by internal and/or external stresses. The explosive fragmentation of hot magma upon contact to external water is experimentally shown in Chapter 2, emphasizing the need for water-entrapment configurations to cause explosive interaction during which extremely high stresses fracture melt in a brittle fashion. The motion through the conduit of vesiculating magma below the fragmentation level, and of the gas-particle/droplet mixture above fragmentation is investigated in Chapter 3. Pressure evo

    Readership

    For research volcanologists, private scientists, professionals, university libraries, government research institutes, graduate students and researchers.

    Table of Contents

    Chapter headings and selected papers: Magma Degassing and Fragmentation: Recent Experimental Advances. Abstract. Introduction. Nucleation. Bubble Growth. Accelerating two-phase flows. Brittle failure. Post-fragmentation effects. Non-explosive degassing. Relaxation geospeedometry of volcanic glass. Bibliography. Phreatomagmatic Explosions. Introduction. Explosive phreatomagmatic volcanism. Physics of volcanic MFCI. Diagnosis and monitoring of phreatomagmatic explosions (volcanic MFCI). Volcanic Conduit Dynamics. Introduction. Review of magma ascent models. Magma ascent dynamics in steady state explosive eruptions. Eruption Column Physics. Introduction. Multiphase flow and the multifield approach. Multifield governing equations. Closure of governing equations. Approaches to analysis of eruption column dynamics. Steady state dynamics. Time-dependent dynamics with constant eruption rate. Time-dependent dynamics with transient eruption rate. Influence of the ambient medium. Conclusion. Plinian Eruption Columns: Particle Transport and Fallout. Introduction. Models of particle transport in plinian columns. Clast dispersal in crosswinds. Assessment of eruption parameters. Pyroclastic Flow Transport Mechanisms. Introduction. Characteristics of ignimbrites and pyroclastic flows. Transport processes of sedimenting particulate flows. Pyroclastic flow models. From model flows to ignimbrites: complexities during emplacement. Concluding remarks. Pyroclastic Surges and Compressible Two-Phase Flow. Introduction. Observations. Theory. Conclusions: surges are hazardous but economically significant. Appendix A: origin of the SFT equations. Appendix B: analysis of surge steam condensation. References. Subject index.

    Details

    No. of pages:
    336
    Language:
    English
    Copyright:
    © 1998
    Published:
    Imprint:
    Elsevier Science
    Print ISBN:
    9780444507082
    Electronic ISBN:
    9780444537751

    About the editors

    A. Freundt

    Affiliations and Expertise

    GEOMAR, Forschungszentrum für Marine Geowissenschaften, Wischhofstrasse 1-3, Geb. 4, D-24148 Kiel, Germany.

    M. Rosi

    Affiliations and Expertise

    Università di Pisa, Dipart. di Scienze della Terra, Via S. Maria, 53, I-56126 Pisa, Italy.

    Reviews

    @from:(S. Self) @qu:...Those who want a timely summary of much widely disseminated work will find it invaluable... It is a very good addition to the volcanological literature and the editors are to be commended. @source:Journal of Volcanology and Geothermal Research @from:(R. Carniel) @qu:...gives the reader access to the status of research and modelling in a series of fields of volcanology that literally accompany him/her from the dynamics of magma vesiculation and fragmentation to the deposits of explosive eruptions. ...this is a most valuable book ... advanced students but also (or especially) professional volcanologists and researchers will find in a single book an impressive amount of high standard and updated information about the topics covered by the book, together with a conspicuous number of relevant references to the literature published in the past and especially in the very last years. @source:Volcano Quarterly Online @from:(J.C. Tanguy) @qu:Cet ouvrage constitue une mise au point et un recueil de données quantitatives fondamentales pour chercheurs et étudiants de haut niveau. @source:Geochronique @from:(C. Oppenheimer) @qu:Almost twenty years ago, at 08:32 Pacific Daylight Time on the 18th May, 1980, a magnitude 5.1 earthquake triggered an explosive eruption of Mount St. Helens which, in turn, triggered huge interest in the physics of volcanic processes. More recently, the pace has, if anything, accelerated thanks to the motivation provided by further well-studied eruptions, including Pinatubo (Philippines) in 1991, and Soufriere Hills volcano (Montserrat) in 1995–1999. An impressive body of literature has accumulated just in the past decade spanning empirical, theoretical and observational approaches; physical models have been tested, validated and compared using laboratory experiments and remote sensing