Physical Modeling of Collapsing Volcanic Columns and Pyroclastic Flows

  • A. Neri
  • G. Macedonio


This chapter presents an overview of physical models of collapsing volcanic columns and pyroclastic flows, and outlines the future modeling prospects on this topic. After a presentation of the modeling approach and a critical review of the developed one-dimensional, steady-state, and homogeneous flow models, the paper describes the main features and results of the more advanced two-dimensional, transient, and two-phase flow models. Such models describe the collapsing volcanic column and pyroclastic flow behavior on an axisymmetric physical domain extending several kilometers in radial and vertical directions, and account for the mechanical and thermal non-equilibrium between gas and solid particles. In the more complete modeling developed to date, the gas phase is composed of hot water vapor leaving the vent and atmospheric air, and the solid phase takes into account one particle size class. Particle collisions are modeled by a kinetic theory for granular flows, and turbulence effects are described by a subgrid scale model in terms of an effective viscosity. The model is able to describe very complex processes related to the dynamics of collapsing volcanic columns and pyroclastic flows, such as eruptive column collapse, the rising of hot plumes from the fountain, the formation of co-ignimbritic clouds from the flow, particle sedimentation effects, and mass-flow rate pulsations of the flow. Preliminary applications to historical eruptions as well as laboratory experiments seem to be consistent with model predictions and are an incentive for new investigations. Despite these important results, such consistency is only qualitative and new greater efforts must be carried out in order to overcome the present modeling limits. This paper tries to outline the future modeling prospects and needs in order to reach an adequate model of collapsing volcanic columns and pyroclastic flows. With this model it will be possible to assess, better than in the past, the volcanic hazard associated with these catastrophic phenomena.


Pyroclastic Flow Water Vapor Content Granular Flow Exit Velocity Column Collapse 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  • A. Neri
    • 1
  • G. Macedonio
    • 2
  1. 1.Gruppo Nazionale per la Vulcanologia, Dipartimento di Scienze della TerraUniversità degli Studi di PisaPisaItaly
  2. 2.Centro di Studio per la Geologia Strutturale e Dinamica dell’Appennino, Dipartimento di Scienze della TerraUniversità di PisaPisaItaly

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