Collaborative Research: Violent Basaltic Explosive Volcanism II: Constraints and Conditions of Basaltic Plinian Eruptions

智力优势：玄武质火山作用最常见的是产生熔岩的渗出，温和的爆炸性斯特龙博利活动或夏威夷火喷泉喷发。然而，一些玄武岩喷发现在被认为是极其猛烈的，即产生广泛的潜水岩浆、次普林尼期和普林尼期瀑布沉积物，这些包括历史上在基拉韦厄（夏威夷）、埃特纳（意大利）和塔拉韦拉（新西兰）的喷发。这些喷发是特别危险的，因为喷发前玄武岩浆的上升速率可能非常高（即，警告时间短至几个小时），也因为它们的前兆可能被忽视或误解。我们开始限制喷发前上升和脱气的条件，允许玄武岩浆喷发在普林尼强度，主要使用公元前122年的埃特纳火山喷发的例子。机制，以抑制或延迟开放系统的行为和促进扩展之间的耦合气体和熔体是必不可少的，允许普林尼喷发的玄武岩浆。我们将通过在德克萨斯大学对公元前122年的Etma熔体进行减压实验，并将实验产物与天然样品进行比较，从质地和化学上来限制岩浆上升和起泡的条件和速率。我们将使用三种不同的技术来量化喷发的火山渣和实验电荷中的囊泡和微晶石种群的范围，以确保可靠的数据集，并允许对技术进行关键比较。最后，我们将测量前和喷发后的挥发分含量的熔融相在同一火山碎屑。更广泛的影响：我们的目标是了解玄武普林尼火山喷发的机制，并将这种理解应用于改善大型玄武火山未来喷发的准备工作。特别是有证据表明，在埃特纳的近代历史中，有几次大规模的次普林尼期到普林尼期的喷发。很可能会发生另一次大规模的爆炸性喷发，并影响到大量人口。由于埃特纳周围的现代人口要多得多，居住区向火山两侧延伸得更远，未来的火山爆发会造成重大的潜在危险。我们将在意大利的一个研讨会上向应急管理机构提交一份结论和影响的摘要，然后在2007年为埃特纳的学生和研究人员举办一个重点研讨会。我们的研究结果还将通过互联网广泛传播，使用由夏威夷大学、得克萨斯大学和意大利INGV主办的链接网站，并以意大利语和英语DVD的形式传播。

Intellectual Merit: Basaltic volcanism most commonly produces effusion of lava, mildly explosive Strombolian activity or Hawaiian fire fountain eruptions. However, some basaltic eruptions are now recognized as extremely violent, i.e. generating widespread phreatomagmatic, subplinian and Plinian fall deposits, these include historical eruptions at Kilauea (Hawaii), Etna (Italy) and Tarawera (New Zealand). These eruptions are particularly dangerous because the ascent rate of basaltic magma prior to eruption can be very high (i.e., warning times as little as a few hours) and because their precursors may be ignored or misunderstood. We set out to constrain the conditions of pre-eruptive ascent and degassing that permitted basaltic magma to erupt at Plinian intensity, principally using the example of the 122 BC eruption of Mt Etna. Mechanisms to suppress or delay open-system behavior and promote extended coupling between gas and melt are essential to permit Plinian eruptions of basaltic magma. We will look to constrain conditions and rates of magma ascent and vesiculation by performingdecompression experiments on the 122 BC Etma melt at University of Texas and comparing experimental products with natural samples, texturally and chemically. We will quantify the range of vesicle and microlite populations in the erupted scoria and experimental charges using three different techniques, to ensure reliable data sets, and to allow critical comparison of the techniques. Finally we will measure pre- and post-eruptive volatile contents of the melt phases in the same pyroclasts. Broader impacts: Our goal is to understand the mechanisms for basaltic Plinian eruptions, with a long-term aim of applying such understanding to improve preparedness for future eruptions at large basaltic volcanoes. In particular there is evidence for several large subplinian to Plinian eruptions in Etna's recent history. It is likely that another large explosive eruption will happen and affect a large population. Because the modern population surrounding Etna is much greater and the inhabited area extends farther up the volcano's flanks, future eruptions pose significant potential hazards. We will present a summary of conclusions and impacts to emergency management agencies at a workshop in Italy followed by a focused workshop for students and researchers at Etna in 2007. Our results will also be widely disseminated via the Internet using linked web sites hosted by University of Hawaii, University of Texas and INGV, Italy and in the form of a DVD in Italian and English.