Understanding Phreatoplinian Volcanism: The Case Study of the 1875 Eruption of Askja Volcano, Iceland.

EAR-0310033Thordarson与爆炸性火山作用相关的最危险的广泛危险是在矿物期喷发期间湿火山灰落下，影响到数万平方公里的地区。白垩纪火山作用是我们科学中一个鲜为人知、被忽视的分支，尽管冰岛全新世40次火山爆发中有一半是这样的。这项研究以1875年冰岛Askja喷发这一历史上唯一的“典型例子”为目标，考察岩浆挥发物和外部水在“驱动”深成期喷发中的作用，以及“干”(深成)和“湿”(深成)破碎过程之间的对比。它的目标是(1)通过比较深成期浮岩和深成/深成浮石之间的成核、生长和囊泡合并的模式来量化岩浆挥发物在深成期喷发中的作用，以及(2)通过分析整个沉积物的粒度分布和所有喷发阶段的碎屑形态来阐明外部水在碎裂中的作用。广泛的影响：这项研究将通过冰岛大学(UI)/夏威夷大学(UH)的联合课程来促进教学、培训和学习。结果将通过互联网以冰岛语(伊利诺伊大学)和英语(密歇根大学)以及在公开讲座上广泛传播。它还将被纳入密歇根大学和伊利诺伊大学教授的火山学课程，每年在希洛开设的暑期学校为第三世界火山学家和大陆大学的本科生开设活火山研究中心。它将在夏威夷大学对一名年轻的女火山学家进行广泛的技术培训。我们也希望以这项研究为跳板，向密歇根大学的其他研究生和本科生介绍冰岛火山，并将冰岛年轻科学家带到美国。基础设施将得到加强，因为赠款将维持和扩大夏威夷的火山物理设施，满足3名教员、5名研究生和6名本科生的需要。这项研究的一个主要重点将是向冰岛的应急管理机构提交结论和影响研讨会的摘要，并在关于火山的城市系列的下一次会议上向民防界更广泛的受众介绍结果。

EAR-0310033ThordarsonThe most dangerous widespread hazard associated with explosive volcanism is wet ash fall during phreatoplinian eruptions, which affects areas of tens of thousands of square kilometers. Phreatoplinian volcanism is a poorly understood and neglected branch of our science, despite featuring in half of the 40 Holocene explosive eruptions in Iceland. This study targets the only historical "type example", the 1875 eruption of Askja in Iceland, to examine the roles of magmatic volatiles and external water in "driving" phreatoplinian eruptions and the contrasts between "dry" (plinian, subplinian) and "wet" (phreatoplinian) fragmentation processes. Its goals are (1) to quantify the roles of magmatic volatiles during phreatoplinian eruption by comparing patterns of nucleation, growth and coalescence of vesicles between phreatoplinian and plinian/subplinian pumices, and (2) to clarify the role of external water at fragmentation by analysis of whole deposit grainsize distribution, and clast morphologies in all eruption phases.Broader impacts: This study will promote teaching, training and learning through conjoint University of Iceland (UI)/University of Hawaii (UH) classes. Results will be broadly disseminated via the Internet in Icelandic (at UI) and English (at UH) and and in public lectures. It will also be incorporated in the volcanology courses taught at UH and UI, in summer schools taught annually in Hilo for the Center for Study of Active Volcanoes to third world volcanologists and to undergraduates from mainland colleges. It will train a young female volcanologist in a wide range of techniques available at University of Hawaii. We also hope to use this study as a "springboard" to introduce other UH graduate and undergraduate students to Icelandic volcanism and bring young Icelandic scientists to the United States. Infrastructure will be enhanced as the grant will sustain and expand the physical volcanology facilities at Hawaii that serve the needs of 3 faculty, 5 graduate students and 6 undergraduates. A major focus of this study will be to present a summary of conclusions and impacts workshop to emergency management agencies in Iceland and to present the result to a wider audience from the civil defense community at the next meeting in the Cities on Volcanoes series.