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The 1980 eruptions of Mount St. Helens, Washington
Book Reviews The 1980 Eruptions of Mount St. Helens, Washington,
ed-
ited by P. W. Lipman and D. R. Mullineaux, U.S.G.S. Professional Paper 1250, 1982, 844 pp., $35.00. THE ERUPTIONof Mount St. Helens in May 1980 was an exceptional volcanic event from several points of view. Fortunately for volcanology it was studied from the beginning, by a team which was remarkable not only by the quality and number of its members but also by the diversity of methods which were put in use. From that came now this fine 844 page book, abundantly illustrated by 470 figures and photographs, accompanied by a coloured geological map at l/50,000. The editors made a deliberate choice to quickly publish the essential facts and the interpretations reached by December 1980, before the end of the eruptive activities. This explains and justifies the caution of preliminary interpretations. The book comprises 62 articles which fall into five groups: volcanic events (84 pp.); geophysical monitoring, including gas and supplement studies (248 pp.); volcanic deposits including geochemistry (343 pp.); effects of the 1980 eruptions (92 pp.); potential hazards (50 pp.). Each group includes a substantial and useful summary, and the index is very detailed. It is difficult in a few words to describe the richness of this collective work. The main theme concerns, of course, the salient features of the catastrophic eruption of the 18th of May: the bulging of the north flank, the landslide and the avalanche-debris flow which resulted, as well as the lateral blast following the abrupt pressure decrease of the cryptodome and the hydrothermal systems. All this was observed, photographed and analysed for the first time. From this, ancient eruptions will be re-interpreted as “Mount St. Helens type”. The impact of the volcanology will be comparable to that of the description of the eruption of La Montagne Pel&e in 1902 for the understanding of Pelean domes and associated n&es ardentes.
Chemical
Reaction Equilibrium Analysis: Theory and Algorithms, by William R. Smith and Ronald W. Missen, Wiley-Interscience, 1982, 364 pp., $42.95.
DETERMINATIONOF the equilibrium configuration of a chemical system, as characterized by the identity, composition, and relative abundances of phases, is a widely used tool of inquiry into geochemical processes. Chemical Reaction Equilibrium Analysis: Theory and Algorithms is a text designed to familiarize the reader with computational methods for solution of the chemical equilibrium problem. The first four chapters cover elementary aspects of equilibrium analysis, such as, the determination of reaction stoichiometry. The last five chapters are the most valuable to geochemists interested in the intricacies of equilibrium calculations. Chapter 5 surveys numerical methods for solution of simultaneous nonlinear equations, which are ubiquitous in both the stoichiometric (equilibrium constant) and nonstoichiometric (minimization) formulations of the chemical equilibrium problem. In Chapter 6 the nonstoichiometric BNR (Brinkley-NASA-RAND) algorithms, and the VCS (Villars-Cruise-Smith) optimized stoichiometry algorithm are introduced for heterogeneous, ideal systems. The authors review models for the excess Gibbs free energy of phases in Chapter 7, and discuss strategies for incorporation of nonideality into the BNR and VCS algorithms. The sen-
1651
This primary contribution is accompanied by new understanding and important data on better known phenomena and their products: plinian eruptions, pumice flows, lahars, composite domes; it is accompanied also by a masterful example of continuous geophysical and multidisciplinary monitoring of an explosive volcano in action. The eruptions of 1980 produced nearly 3 km’ of debris, but more than 9/ 10 are older material entrained in the flow of May 18. Inflation of the flank of the volcano, which gave rise to them, resulted from the intrusion of a cryptodome; it was emplaced laterally because of the obstruction of the central chimney by a resistant pre-existing dome and by the fragility of the north flank, probably resulting from the intrusion of the Goat Rocks dome. One cannot avoid the conclusion that, without the mechanical anisotropy of the volcano, consequent on its history, the eruption of May 18 would only have been magmatic, of relatively small volume and much less destructive. Aher having demonstrated the importance of geophysical methods, the book urges that one should not underestimate the importance of the geological approach in volcano monitoring. This was also the lesson which came out of the former study of the history of the volcano, completed here by Mulhneaux and Crandell. The activity of Mount St. Helens is thus perhaps far from being ended. It would be unjust under these circumstances to reproach the editors for not having included a more synthetic chapter, or more definitive conclusions: these would have been without doubt premature. The rapidity with which this book has been published is not the least of its merits. The price is modest for a well-produced work of this size. This book will take its place among the classics of volcanology, and this is a prediction without risk of error. Departement de Geologie Vniversite de Clermont-Ferrand Clermont- Ferrand, FRANCE
Pierre M. Vincent
sitivity of computed compositions to variations in pressure and/or temperature, as well as to errors in thermodynamic data, is considered in Chapter 8. The last chapter discusses odds and ends such as: initial estimates, isotopic calculations, and equilibrium calculations subject to alternative constraints (e.g., adiabatic systems). The appendices contain computer programs for the various algorithms. Unfortunately, the authors made the “fatal” error of retyping the programs instead of reproducing a computer listing. The FORTRAN program in Appendix A does not generate the sample output. In addition, the authors have indicated that an error is present in the retyped BASIC listing on page 275. Readers should consult the authors for a complete list of errata. Although the approach and scope of this book are similar to Van Zeggeren and Storey’s The Computation of Chemical Equilibria, the greater depth of coverage, the numerous examples and problems, and the well integrated computer programs make this volume superior for self-study. Chemical Reaction Equilibrium Analysis: Theory and Algorithms is an important addition to computational arsenal of the geochemist; I enthusiastically recommend it. Department of Geology Tulane University New Orleans, LA 70118
George C. Flowers
ed-
ited by P. W. Lipman and D. R. Mullineaux, U.S.G.S. Professional Paper 1250, 1982, 844 pp., $35.00. THE ERUPTIONof Mount St. Helens in May 1980 was an exceptional volcanic event from several points of view. Fortunately for volcanology it was studied from the beginning, by a team which was remarkable not only by the quality and number of its members but also by the diversity of methods which were put in use. From that came now this fine 844 page book, abundantly illustrated by 470 figures and photographs, accompanied by a coloured geological map at l/50,000. The editors made a deliberate choice to quickly publish the essential facts and the interpretations reached by December 1980, before the end of the eruptive activities. This explains and justifies the caution of preliminary interpretations. The book comprises 62 articles which fall into five groups: volcanic events (84 pp.); geophysical monitoring, including gas and supplement studies (248 pp.); volcanic deposits including geochemistry (343 pp.); effects of the 1980 eruptions (92 pp.); potential hazards (50 pp.). Each group includes a substantial and useful summary, and the index is very detailed. It is difficult in a few words to describe the richness of this collective work. The main theme concerns, of course, the salient features of the catastrophic eruption of the 18th of May: the bulging of the north flank, the landslide and the avalanche-debris flow which resulted, as well as the lateral blast following the abrupt pressure decrease of the cryptodome and the hydrothermal systems. All this was observed, photographed and analysed for the first time. From this, ancient eruptions will be re-interpreted as “Mount St. Helens type”. The impact of the volcanology will be comparable to that of the description of the eruption of La Montagne Pel&e in 1902 for the understanding of Pelean domes and associated n&es ardentes.
Chemical
Reaction Equilibrium Analysis: Theory and Algorithms, by William R. Smith and Ronald W. Missen, Wiley-Interscience, 1982, 364 pp., $42.95.
DETERMINATIONOF the equilibrium configuration of a chemical system, as characterized by the identity, composition, and relative abundances of phases, is a widely used tool of inquiry into geochemical processes. Chemical Reaction Equilibrium Analysis: Theory and Algorithms is a text designed to familiarize the reader with computational methods for solution of the chemical equilibrium problem. The first four chapters cover elementary aspects of equilibrium analysis, such as, the determination of reaction stoichiometry. The last five chapters are the most valuable to geochemists interested in the intricacies of equilibrium calculations. Chapter 5 surveys numerical methods for solution of simultaneous nonlinear equations, which are ubiquitous in both the stoichiometric (equilibrium constant) and nonstoichiometric (minimization) formulations of the chemical equilibrium problem. In Chapter 6 the nonstoichiometric BNR (Brinkley-NASA-RAND) algorithms, and the VCS (Villars-Cruise-Smith) optimized stoichiometry algorithm are introduced for heterogeneous, ideal systems. The authors review models for the excess Gibbs free energy of phases in Chapter 7, and discuss strategies for incorporation of nonideality into the BNR and VCS algorithms. The sen-
1651
This primary contribution is accompanied by new understanding and important data on better known phenomena and their products: plinian eruptions, pumice flows, lahars, composite domes; it is accompanied also by a masterful example of continuous geophysical and multidisciplinary monitoring of an explosive volcano in action. The eruptions of 1980 produced nearly 3 km’ of debris, but more than 9/ 10 are older material entrained in the flow of May 18. Inflation of the flank of the volcano, which gave rise to them, resulted from the intrusion of a cryptodome; it was emplaced laterally because of the obstruction of the central chimney by a resistant pre-existing dome and by the fragility of the north flank, probably resulting from the intrusion of the Goat Rocks dome. One cannot avoid the conclusion that, without the mechanical anisotropy of the volcano, consequent on its history, the eruption of May 18 would only have been magmatic, of relatively small volume and much less destructive. Aher having demonstrated the importance of geophysical methods, the book urges that one should not underestimate the importance of the geological approach in volcano monitoring. This was also the lesson which came out of the former study of the history of the volcano, completed here by Mulhneaux and Crandell. The activity of Mount St. Helens is thus perhaps far from being ended. It would be unjust under these circumstances to reproach the editors for not having included a more synthetic chapter, or more definitive conclusions: these would have been without doubt premature. The rapidity with which this book has been published is not the least of its merits. The price is modest for a well-produced work of this size. This book will take its place among the classics of volcanology, and this is a prediction without risk of error. Departement de Geologie Vniversite de Clermont-Ferrand Clermont- Ferrand, FRANCE
Pierre M. Vincent
sitivity of computed compositions to variations in pressure and/or temperature, as well as to errors in thermodynamic data, is considered in Chapter 8. The last chapter discusses odds and ends such as: initial estimates, isotopic calculations, and equilibrium calculations subject to alternative constraints (e.g., adiabatic systems). The appendices contain computer programs for the various algorithms. Unfortunately, the authors made the “fatal” error of retyping the programs instead of reproducing a computer listing. The FORTRAN program in Appendix A does not generate the sample output. In addition, the authors have indicated that an error is present in the retyped BASIC listing on page 275. Readers should consult the authors for a complete list of errata. Although the approach and scope of this book are similar to Van Zeggeren and Storey’s The Computation of Chemical Equilibria, the greater depth of coverage, the numerous examples and problems, and the well integrated computer programs make this volume superior for self-study. Chemical Reaction Equilibrium Analysis: Theory and Algorithms is an important addition to computational arsenal of the geochemist; I enthusiastically recommend it. Department of Geology Tulane University New Orleans, LA 70118
George C. Flowers