The Dynamics of Short-Duration, Unsteady Volcanic Eruptions

短期不稳定火山喷发的动力学

• 批准号: 0810258
• 负责人: Amanda Clarke
• 金额: $ 30.47万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810258&HistoricalAwards=false
• 关键词: Dynamics; Short; Duration; Unsteady; Volcanic

Approximately 30 of the more than 550 historically active volcanoes in the world are adequately monitored despite the threats they pose to encroaching human populations. Better predictions of volcanic eruption timing and scale are critical for reducing risk to these vulnerable populations. To that end, scientists are attempting to identify currently unrecognized patterns in explosive eruption dynamics and subsequently build reliable predictive models. Computer models of large, sustained (Plinian) eruptions, like the eruption of Mt. St. Helens on May 18, 1980, or the June 12, 1991 eruption of Pinatubo volcano in the Philippines, form the basis of our current understanding. However, despite the fact that pulsating or unsteady source properties are thought to have significant impact on eruption behavior, such models are necessarily simplified by time-averaging key source properties such as density and velocity. In response to this apparent disconnect, this research aims to establish robust relationships between unsteady source conditions and explosive eruption dynamics. The study will focus on small, short-lived, highly unsteady (vulcanian) eruptions, which occur much more frequently than Plinian eruptions, and are thus a valuable and accessible source of data for enhancing general understanding of eruption dynamics and improving models. Collapsing eruption columns and resulting pyroclastic flows (avalanches of hot gas, blocks and ash) are one of the deadliest phenomena produced in explosive volcanic eruptions. The complexity and danger presented by volcanic eruptions motivates the laboratory investigations that will take place with the aim to define the transition between stable, rising eruption columns and unstable, pyroclastic-flow-producing columns in terms of the unsteady forces driving the eruption. Of particular interest is how variations in the initial buoyancy and momentum forces influence changes in the ash and velocity distribution of these flows. The team will also test the effectiveness of existing mathematical models of eruptions in capturing the behavior of simple laboratory experiments. Simultaneously, they will assess whether the same models are valid representations of real volcanic eruptions. The ultimate goal of the project is to establish theoretical understanding of a wide-range of flows generated by impulsive, unsteady sources, including large-scale explosive volcanic eruptions, industrial explosions, contaminant plumes, forest fires and many other phenomena.

在世界上550多座历史上活跃的火山中，约有30座受到充分监测，尽管它们对入侵的人口构成威胁。 更好地预测火山爆发的时间和规模对于减少这些脆弱人群的风险至关重要。 为此，科学家们正试图确定目前尚未认识到的爆炸性喷发动力学模式，并随后建立可靠的预测模型。 计算机模型的大，持续（普林尼）喷发，如火山喷发。1980年5月18日的圣海伦斯火山或1991年6月12日菲律宾皮纳图博火山的喷发构成了我们目前理解的基础。 然而，尽管脉动或不稳定的源属性被认为对喷发行为有显着的影响，这样的模型必须简化的时间平均的关键源属性，如密度和速度。 针对这种明显的脱节，本研究的目的是建立强大的不稳定源条件和爆炸喷发动力学之间的关系。 这项研究将侧重于小型、短暂、高度不稳定的（火山）喷发，这种喷发比普林尼式喷发频繁得多，因此是提高对喷发动力学的一般了解和改进模型的宝贵和可获得的数据来源。 坍塌的喷发柱和由此产生的火山碎屑流（热气、石块和灰烬的雪崩）是火山爆发中产生的最致命的现象之一。火山爆发的复杂性和危险性促使实验室进行调查，目的是确定稳定的，上升的喷发柱和不稳定的，火山碎屑流产生柱之间的过渡驱动喷发的不稳定力。 特别感兴趣的是如何在初始浮力和动量力的变化影响这些流量的灰和速度分布的变化。 该团队还将测试现有的火山喷发数学模型在捕捉简单实验室实验行为方面的有效性。同时，他们将评估同样的模型是否是真实的火山爆发的有效代表。该项目的最终目标是从理论上理解由脉冲、不稳定源产生的各种流动，包括大规模爆炸性火山爆发、工业爆炸、污染物羽流、森林火灾和许多其他现象。