Lava Dome Collapses : Their Mechanisms and Short-Term Forecasting

熔岩穹顶塌陷：其机制和短期预测

• 批准号: 0809543
• 负责人: Eliza Calder
• 金额: $ 26.09万
• 依托单位: SUNY at Buffalo
• 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: 2008-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0809543&HistoricalAwards=false
• 关键词: Lava; Dome; Collapses; Their; Mechanisms

Lava domes are piles of viscous magma that, in essence, form bulbous plugs on top of volcanic vents. They grow slowly as partially solidified magma is squeezed up the volcanic conduit, and they can host high internal pressures as gases exsolving from the magma try to escape. Lava dome eruptions are notorious for they often suddenly transformation from being benignly effusive to violently explosive. Sudden removal of these plugs, either by vertically-driven explosions, caused once the internal gas pressure exceeds the tensile strength of rock, or sudden collapse and spontaneous disintegration as the piles grow and become unstable, can have devastating consequences. These collapse events spawn one of the major hazard in volcanology; devastating pyroclastic density currents, which move down the flanks of the volcano at speeds of up to 60 m/s. This project concerns the improved understanding and forecasting of lava dome collapses and has immediate and practical applications pertaining to the management of several on-going volcanic crisis. The work will be based on the Soufrière Hills volcano (SHV) eruption, Montserrat, combined with preliminary comparative studies from two other active lava dome eruptions, Mount St Helens, USA, and Santiaguito, Guatemala. Such eruptions occur with relative frequency, are potentially extremely destructive and can continue for years-to decades. The real merits therefore, will be reaped when relationships unearthed during this study are usefully and successfully applied to dome forming eruptions elsewhere.The fundamental objective of this work is to stringently quantify aspects of activity associated with lava dome failure and collapse including information on the timing and location of rockfalls and pyroclastic flows, as well as the nature of other precursory activity. The project will address three issues that require further attention: differentiating failure modes; identifying structural controls; and treating collapses as part of a continuous process of mass wasting rather than discrete independent events. By investigating along these themes, this work will validate existing models and constrain a number of current limitations. The results of this work will provide the basis from which statistically-driven models can be developed, in order to construct a short-term forecasting model of mass wasting at lava domes. The novelty and impact of this study hinges on: Innovative techniques for comparing disparate data sets of monitoring data, and the generation of an important record of dome activity that will be useful to the volcanological community; Understanding continuous growth and wasting processes allowing assessments to be made about physical mechanisms but also providing a basis for testing statistical models (the quality of which is enhanced by collection of large data sets); The fusion of data from digital elevation models, thermal images, and gas plume maps, developing a truly integrative approach to understanding dome instability.

熔岩穹丘是一堆粘稠的岩浆，本质上是在火山口顶部形成的球状塞子。当部分凝固的岩浆被火山管道挤压时，它们生长缓慢，当岩浆中的气体试图逸出时，它们可以承受很高的内部压力。熔岩穹丘喷发是臭名昭著的，因为它们经常突然从温和的喷发转变为剧烈的爆炸。一旦内部气体压力超过岩石的抗拉强度，通过垂直驱动的爆炸，或者随着桩的增长和变得不稳定，突然倒塌和自发解体，这些塞子的突然拆除可能会产生毁灭性的后果。这些崩塌事件产生了火山学中的主要危险之一;毁灭性的火山碎屑密度流，以高达60米/秒的速度沿着火山的侧翼向下移动。该项目涉及改进对熔岩穹丘崩塌的理解和预测，并在管理几个正在进行的火山危机方面具有直接和实际的应用。这项工作将以蒙特塞拉特苏弗里耶尔山火山喷发为基础，并结合对美国圣海伦山和危地马拉马奎托山另外两次活跃的熔岩穹丘喷发的初步比较研究。这种喷发相对频繁，具有潜在的极大破坏性，并可能持续数年至数十年。因此，真实的优点，将收获时，在这项研究中出土的关系是有用的，并成功地应用到圆顶形成eurtheseleph.The基本目标，这项工作是严格量化方面的活动与熔岩圆顶失败和崩溃，包括信息的时间和位置的落石和火山碎屑流，以及其他火山活动的性质。该项目将解决需要进一步关注的三个问题：区分故障模式;确定结构控制;将倒塌视为质量浪费的连续过程的一部分，而不是离散的独立事件。通过研究沿着这些主题，这项工作将验证现有的模型和约束当前的一些限制。这项工作的结果将提供的基础上，可以开发的预测驱动的模型，以构建一个短期预测模型的质量浪费在熔岩圆顶。这项研究的新奇和影响取决于：用于比较不同监测数据集的创新技术，以及对火山学界有用的圆顶活动的重要记录的生成;了解持续的生长和消耗过程，可以对物理机制进行评估，但也为测试统计模型提供了基础（通过收集大量数据集来提高质量）;数字高程模型、热图像和气体羽流图的数据融合，开发了一种真正的综合方法来理解圆顶不稳定性。