Computer Simulations Of Explosive Volcanic Eruptions

We have adapted computer codes that provide such solutions to study explosive volcanic phenomena. These fully nonlinear conservation equations are cast in two-dimensional cylindrical coordinates, which with closure equations comprise 16 equations with 16 unknown variables. Solutions for several hundred seconds of simulated eruption time require two to three hours of a Cray-1 computer time. Over 100 simulations have been run to simulate the physics of highly unsteady blasts, sustained and steady Plinian eruptions, fountaining, column eruptions, and multiphase flow of magma in lithospheric conduits. The unsteady-flow calculations show resemblance to shock-tube physics with propagation of shock waves into the atmosphere and rarefaction waves down the volcanic conduit. Steady-flow eruption simulations demonstrate the importance of supersonic flow and over pressure of erupted jets of tephra and gases in determining whether the jet will buoyantly rise or collapse back to the earth as a fountain. Flow conditions within conduits rising through the lithosphere determine eruptive conditions of overpressure, velocity, bulk density, and vent size. Such conditions within conduit systems are thought to be linked to low-frequency, sustained seismicity known as volcanic tremor. These calculations demonstrate the validity of some analytical eruption calculations under limited conditions. 31 refs., 10 figs., 1 tab.

Volcanic eruptions are common, with more than 50 volcanic eruptions in the United States alone in the past 31 years. These eruptions can have devastating economic and social consequences, even at great distances from the volcano. Fortunately many eruptions are preceded by unrest that can be detected using ground, airborne, and spaceborne instruments. Data from these instruments, combined with basic understanding of how volcanoes work, form the basis for forecasting eruptionsâ€"where, when, how big, how long, and the consequences. Accurate forecasts of the likelihood and magnitude of an eruption in a specified timeframe are rooted in a scientific understanding of the processes that govern the storage, ascent, and eruption of magma. Yet our understanding of volcanic systems is incomplete and biased by the limited number of volcanoes and eruption styles observed with advanced instrumentation. Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing identifies key science questions, research and observation priorities, and approaches for building a volcano science community capable of tackling them. This report presents goals for making major advances in volcano science.

The Physics of Explosive Volcanic Eruptions includes seven review papers that outline our current understanding of several aspects of the physical processes affecting magma during volcanic eruptions. An introductory chapter highlights research areas where our understanding is incomplete, or even completely lacking, and where work needs advancing if our knowledge of volcanic processes is to be substantially improved. The book covers topics on the physical properties of silicic magma, vesiculation processes, conduit flow and fragmentation, gas loss from magmas during eruption, models of volcanic eruption columns, tephra dispersal and pyroclastic density currents.

Understanding the physical behavior of volcanoes is key to mitigating the hazards active volcanoes pose to the ever-increasing populations living nearby. The processes involved in volcanic eruptions are driven by a series of interlinked physical phenomena, and to fully understand these, volcanologists must employ various physics subdisciplines. This book provides the first advanced-level, one-stop resource examining the physics of volcanic behavior and reviewing the state-of-the-art in modeling volcanic processes. Each chapter begins by explaining simple modeling formulations and progresses to present cutting-edge research illustrated by case studies. Individual chapters cover subsurface magmatic processes through to eruption in various environments and conclude with the application of modeling to understanding the other volcanic planets of our Solar System. Providing an accessible and practical text for graduate students of physical volcanology, this book is also an important resource for researchers and professionals in the fields of volcanology, geophysics, geochemistry, petrology and natural hazards.

A summary of insights into key aspects of explosive volcanic eruptions, arranged into chapters in order of the processes involved, from the hot magma releasing gases as it rises through the Earth's crust to the final deposition of materials upon the Earth's surface.

An advanced textbook and reference resource examining the physics of volcanic behavior and the state of the art in modeling volcanic processes.

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to begin work on combining two modeling approaches in order to advance the state-of-the-art in simulating and predicting explosive volcanic eruption dynamics and their effects. The authors began applying the CFDLIB family of codes for the near-field (high temperature, velocity, and particle concentration) region of an explosive eruption. The authors also applied the RAMS meteorological code to model the far-field dynamics of eruption clouds and ash fallout. Initial test runs were conducted in preparation for full-scale simulations that would eventually couple the two models for the most comprehensive volcano simulation tool to date. Eventual applications include aviation hazards, risk assessment, and extension to atmospheric collateral effects of conventional and nuclear weapons.