Influence of Magma Properties on the Dynamics of Explosive Eruptions

岩浆性质对爆炸性喷发动力学的影响

• 批准号: 8719894
• 负责人: Haraldur Sigurdsson
• 金额: $ 11.8万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-04-01 至 1990-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8719894&HistoricalAwards=false
• 关键词: Influence; Magma; Properties; Dynamics; Explosive

Collaborative studies in physical volcanology and experimental petrology on products of explosive eruptions of El Chichon (1982) and Vesuvius (79 AD) have elucidated the dependence of eruption processes on magma properties. Variation in mass eruption rate during the 79 A.D. Vesuvius eruption produced complex compositional gradients in the erupted products, as two contrasting magmas were mixed during withdrawal from the chamber. The extent of mixing is closely linked to mass eruption rate, as proposed on theoretical grounds for compositionally-stratified reservoirs, and demonstrates that geochemical gradients in volcanic deposits can only be interpreted in conjunction with information about eruption dynamics. Modelling of the Vesuvius and El Chichon sequences using petrologically-inferred intensive parameters has shown that the evolution of eruptive processes is consistent with current models of eruption column behavior and that differences between events at the two centers can be attributed to contrasting volatile contents, crystallinity and viscosity of their respective magmas. New techniques in physical volcanology have now provided the means to calculate the intensity (mass eruption rate) of recent and ancient explosive eruptions. Analysis of the available global data base on intensity and magnitude (total volume of erupted magma) of explosive eruptions reveals a close correlation, suggesting a dependence of intensity on magnitude and in turn, on reservoir size. Eruptions with intensities in excess of 2x10-8 kg/s are invariably associated with major pyroclastic flow generation and caldera collapse. A correlation also exists between the runout distance of pyroclastic flows and the intensity of the preceding plinian phase. The predictive power of these observations is of great significance to volcanic hazards studies. This project will continue work in physical volcanology and experimental petrology and apply the results of previous studies to an investigation of intensity, magnitude, and magmatic composition of ancient explosive eruptions from the Cascade Range of the U. S. The study should contribute to an understanding of eruptive processes, magma evolution and hazards assessment of this region.

物理火山学和实验火山学的合作研究 El Chichon火山爆发产物的岩石学（1982年） 和维苏威火山（公元79年）已经阐明了火山喷发的依赖性， 对岩浆性质的影响 喷发速率的变化 在公元79年维苏威火山爆发期间 喷发产物中的成分梯度， 在从腔室中取出的过程中，对比鲜明的岩浆混合在一起。 混合的程度与质量喷发率密切相关， 提出的理论基础上组成分层 地球化学梯度，并表明， 火山沉积物只能结合 有关喷发动力学的信息。 维苏威火山模型 和El Chichon序列使用岩石学推断密集 参数表明，喷发过程的演变是 与目前的喷发柱行为模型一致， 两个中心的事件之间的差异可能是 归因于对比的挥发物含量、结晶度和 它们各自的岩浆粘度。 物理学新技术 火山学现在提供了计算 近代和古代爆炸物强度（质量喷发率） 爆发。 分析现有的全球数据库， 强度和规模（喷发岩浆的总体积） 爆炸性喷发揭示了密切的相关性，这表明 强度对震级的依赖性，进而对水库的依赖性 尺寸 强度超过2x 10 -8 kg/s的喷发是 总是与主要的火山碎屑流产生有关， 火山口坍塌 在跳动量与 火山碎屑流的距离和强度 Plinian阶段 这些观察的预测能力是 对火山灾害研究具有重要意义。 这个项目 将继续从事物理火山学和实验性的研究， 岩石学，并应用以前的研究结果， 强度、震级和岩浆成分调查 美国喀斯喀特山脉古代爆发的证据。S. 这项研究将有助于了解爆发性 岩浆作用、岩浆演化及灾害评价。