Phreatoplinian Signatures of the 1991 Explosive Eruptions of Hudson Volcano, Chile

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。许多大型火山被冰覆盖，因此，当它们喷发时，可能会有高温岩浆和融水相互作用的可能性，例如在美国的太平洋西北部地区。这可能会导致灾难性的洪水或爆炸活动，对周围地区的社区构成重大危险。1991年智利哈德逊火山的冰盖喷发是二十世纪最大的喷发之一。由于广泛的火山灰和洪水，它在阿根廷和智利造成了价值超过850万美元的损失。这项拟议的研究试图以1991年哈德逊事件为例，研究冰川融水在影响火山爆发性质方面的潜在作用。岩浆与冰川熔水的相互作用在喷发产物中产生了独特的特征，可以用分析地球化学和扫描电子显微镜进行研究。哈德逊火山产物广泛扩散的特征表明，除了岩浆的初级脱气作用外，还发生了大量的岩浆和水的相互作用。因此，这项研究的一个主要目标将是试图确定1991年哈德逊矿床中岩浆/水相互作用的信号，并评估其对整个喷发的重要性。这项研究的结果对于认识大型层状火山古代沉积物中的岩浆/水相互作用具有更广泛的意义，从而有助于更准确地评估未来的喷发方式及其潜在的火山灾害。研究计划包括使用FTIR分析1991年喷发的年轻颗粒的挥发物含量，以评估喷发期间阻止脱气的可能性，对颗粒表面进行扫描电子显微镜成像，以寻找“湿”与“干”的熔融岩浆活动特征，以及进行晶体尺寸分布分析，以评估从喷发的初始玄武岩阶段开始的岩浆成分的热历史和分期历史。此外，还将进行粒度分析和浮石孔隙度测量，以评估岩浆/水相互作用对破碎效率的潜在作用。该项目将资助一个为期一年的博士后职位。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Many large volcanoes are ice-covered and, consequently, when they erupt there is the potential for the interaction of high temperature magma and melt-water, such as in the Pacific Northwest region of the United States. This may result in the generation of catastrophic floods or explosive activity that poses significant hazards to communities in the surrounding area. The 1991 eruption of the ice-covered Hudson volcano in Chile was one of the largest explosive eruptions of the twentieth century. It caused over $8.5 million dollars worth of damage in Argentina and Chile as a result of extensive fallout of volcanic ash and flooding. This proposed research seeks to examine the potential role of glacial melt-water in affecting the nature of explosive volcanic eruptions using the 1991 Hudson event as a case study. The interaction of magma with glacial melt-water produces distinctive characteristics in the products of the eruption that can be studied by analytical geochemistry and scanning electron microscopy. Characteristics of the widespread dispersal of the Hudson volcanic products suggest that significant interactions of magma and water took place in addition to primary degassing of the magma. A principal objective of the research will thus be to try to identify the signal of magma/water interactions in the 1991 Hudson deposits and assess its importance to the overall eruption. The findings of the study should have broader significance for the recognition of magma/water interactions in the ancient deposits of large stratovolcanoes and will thus contribute to more precise assessments of future eruption styles and their potential volcanic hazards. The research plan includes the analysis of the volatile content of juvenile particles from the 1991 eruptions using FTIR to assess the potential for arrested degassing during the eruption, SEM imaging of particle surfaces to search for features of 'wet' versus 'dry' phreatomagmatic activity, and crystal size distribution analysis to evaluate the thermal and staging histories of magmatic components from the initial basaltic phase of the eruption. In addition, grain size analysis and pumice vesicularity measurements will be carried out to evaluate the potential role of magma/water interactions on fragmentation efficiency. The project will fund a one-year post-doctoral position.