Ending a Powerful Explosive Eruption: The Case Study of Novarupta 1912, Alaska

结束强烈的爆炸性喷发：阿拉斯加诺瓦鲁普塔 1912 的案例研究

• 批准号: 1348080
• 负责人: Bruce Houghton
• 金额: $ 33.35万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1348080&HistoricalAwards=false
• 关键词: Ending; Powerful; Explosive; Eruption; Case

Short-lived but violent explosive episodes frequently occur during long-lived lava-forming eruptions at our larger volcanoes. Similar eruptions also occur during the build-up to or wind-down from powerful steady eruptions as seen at Mount Pinatubo in 1991. At least 24 such eruptions have occurred in the last 10 years in 12 different countries. These eruptions had few warning signs but yet impacted nearby regions with large, growing populations. The novelty of this study is its focus on an exceptionally well-studied event at Novarupta volcano, Alaska in 1912, which was the largest explosive eruption in the last 100 years. Three powerful eruption pulses, over approximately 60 hours, were followed by a series of violent, short explosions ejecting blocks showing a diverse range of magma textures. These textures form 'fingerprints' to the processes that caused the change in style of activity at the volcano. The project uses a variety of newly developed techniques to capture the rates of processes of gas release and escape in the shallow portions of the volcano's plumbing system. The techniques have in common that they are microanalysis of features of the erupted material on scales of millimeters to micrometers. They include 2D and 3D imaging of vesicles, i.e., the gas bubbles in the erupted material, and measurement of the residual gases in and the permeability of the blocks. The central aim of this study is to reconstruct the architecture of the shallow magma plumbing, and constrain the conditions that led to a transition from a powerful steady eruption style into a series of short unsteady pulsing explosions.The project will involve exchange of material, students and ideas between University of Hawaii at Manoa, University of California at Berkeley and Rice University with Université de Savoie, and Université d'Orléans, in France. Two new initiatives, Students to Schools and Teachers in the Field, are aimed at contact and dialog with school teachers and classes to motivate high school students to consider the earth sciences as a field of study in their undergraduate program.

在我们较大的火山长寿命的熔岩形成喷发期间，经常发生短暂但剧烈的爆炸事件。类似的喷发也发生在强大的稳定喷发的积聚或减弱期间，如1991年在皮纳图博山看到的那样。在过去10年里，在12个不同的国家至少发生了24次这样的火山爆发。 这些火山爆发几乎没有警告信号，但却影响了附近人口众多且不断增长的地区。这项研究的新奇之处在于，它关注的是1912年阿拉斯加诺瓦鲁普塔火山的一次研究非常充分的事件，这是过去100年来最大的爆炸性喷发。在大约60个小时的三次强烈的喷发脉冲之后，发生了一系列剧烈的短暂爆炸，喷出了各种各样的岩浆结构。这些纹理形成了导致火山活动风格变化的过程的“指纹”。 该项目使用各种新开发的技术来捕捉火山管道系统浅层气体释放和逃逸过程的速率。 这些技术的共同点是，它们都是对喷发物质的特征进行毫米至微米尺度的微观分析。 它们包括囊泡的二维和三维成像，即，喷出物中的气泡，以及测量块体中的残余气体和渗透性。这项研究的主要目的是重建浅层岩浆管道的结构，并限制导致从强大的稳定喷发风格转变为一系列短暂的不稳定脉冲爆炸的条件。该项目将涉及夏威夷大学马诺阿分校、加州大学伯克利分校和莱斯大学与萨瓦大学和奥尔良大学之间的材料、学生和思想交流。在法国两项新的倡议，学生到学校和教师在外地，旨在接触和对话，与学校教师和班级，以激励高中生考虑地球科学作为一个研究领域，在他们的本科课程。