FIAMME: (An international collaboration for a) Framework for Ignimbrite Analysis Methodologies for Modelling and hazard Evaluation

FIAMME：（a）用于建模和危害评估的燃烬分析方法框架的国际合作

• 批准号: NE/Y003306/1
• 负责人: Rebecca Williams
• 金额: $ 10.84万
• 依托单位: University of Hull
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY003306%2F1
• 关键词: FIAMME; international; collaboration; Framework; Ignimbrite

Pyroclastic density currents (PDCs) are deadly flows of ash, gas and rocks that form during volcanic eruptions. They can travel up to 200 km/h with internal temperatures up to 1000 degC. They pose one of the greatest volcanic hazards to ever-increasing populations near active volcanic centres, and are responsible for over 90,000 deaths since 1600 AD. Understanding how these currents form and what controls their dynamic flow behaviour in time and space is fundamental to improving the predictive models that we use for hazard assessments. Sadly, our understanding of PDCs is still limited, and their occurrence continues to result in tragedies. Even relatively small PDCs can travel tens of kilometers, over hills and barriers, and even over water. They are also very destructive as they are capable of carrying large volcanic boulders, are highly abrasive, and can deposit tens of meters of sediment across wide areas. Their behaviour is controlled by their internal dynamics, such as how the different particles of ash and rock interact with each other and the gas pressure between them, as well as how the current responds to the ground surface over which it travels. It is critically important that we not only understand their internal dynamics, but are also able to define fundamental equations that describe them, in order to build better hazard simulations. But, we can't see inside a PDC as it flows during an eruption, so these internal dynamics are unknown to us.As PDCs flow, they deposit ash and rocks, leaving behind a record of their passing in the rocks. The structure of these deposits can be highly complicated, capturing what appear to be changes in how the PDC was behaving through time. Our understanding of PDCs has been largely driven by our analysis of these deposits (and indeed, where they do not deposit and even erode), but many of these interpretations are speculative. Despite significant advances in our understanding of PDCs, there are still fundamental gaps in our understanding of their physical processes, how these change with time and space, and how this results in their high mobility and destructive behaviour. Numerical models and flume experiments aim to address these research gaps. We can simulate certain aspects of PDCs, at various scales, to describe their fundamental physics. We hope to then build computer models that simulate PDCs and predict where they may flow during volcanic eruptions. This would transform hazard assessment for communities living with volcanic hazards. To date, as a community of researchers we haven't been able to model the complexity of these currents that we understand from our field studies. We have not systematically collected the right kind of data, and do not have agreed measurement standards to feed into our models. Models that test the relationships between deposit properties and the currents that formed them are critical, but are hindered by a lack of consistently collected, comparable, quantified datasets of field deposits to both inform and validate against. This project aims to bring together global experts in field studies, numerical models and flume experiments to address this challenge. We will develop a database of all known case studies of PDC deposits, identify the most robust methodologies we have to describe and analyse deposits and develop a framework that will guide a future generation of volcanologists.

火山碎屑密度流 (PDC) 是火山喷发期间形成的致命的火山灰、气体和岩石流。它们的行驶速度可达 200 公里/小时，内部温度高达 1000 摄氏度。它们对活跃火山中心附近不断增加的人口构成了最大的火山危害之一，自公元 1600 年以来已导致 90,000 多人死亡。了解这些电流如何形成以及控制它们在时间和空间上的动态流动行为的因素对于改进我们用于危险评估的预测模型至关重要。遗憾的是，我们对PDC的了解仍然有限，而它们的发生却不断造成悲剧。即使相对较小的 PDC 也可以行驶数十公里、翻山越岭、甚至越过水面。它们的破坏性也很大，因为它们能够携带大型火山巨石，具有很强的磨蚀性，并且可以在大范围内沉积数十米的沉积物。它们的行为受其内部动力学控制，例如灰烬和岩石的不同颗粒如何相互作用以及它们之间的气压，以及电流如何对其流经的地面做出反应。至关重要的是，我们不仅要了解它们的内部动态，而且还要能够定义描述它们的基本方程，以便建立更好的危险模拟。但是，当 PDC 在喷发期间流动时，我们无法看到其内部，因此这些内部动态对我们来说是未知的。当 PDC 流动时，它们会沉积火山灰和岩石，留下它们在岩石中经过的记录。这些存款的结构可能非常复杂，反映了 PDC 随着时间的推移表现的变化。我们对 PDC 的理解很大程度上是由我们对这些沉积物的分析（事实上，它们不沉积甚至侵蚀的地方）推动的，但其中许多解释都是推测性的。尽管我们对 PDC 的理解取得了重大进展，但我们对它们的物理过程、它们如何随时间和空间变化以及这如何导致它们的高流动性和破坏性行为的理解仍然存在根本差距。数值模型和水槽实验旨在弥补这些研究空白。我们可以在不同的尺度上模拟 PDC 的某些方面，以描述它们的基本物理原理。我们希望随后建立计算机模型来模拟 PDC 并预测它们在火山喷发期间可能流动的位置。这将改变对存在火山灾害的社区的灾害评估。迄今为止，作为一个研究人员群体，我们还无法对我们从实地研究中了解到的这些电流的复杂性进行建模。我们没有系统地收集正确的数据，也没有商定的测量标准来输入我们的模型。测试矿床属性与形成它们的水流之间关系的模型至关重要，但由于缺乏一致收集的、可比较的、量化的现场矿床数据集来提供信息和验证，该模型受到阻碍。该项目旨在汇集现场研究、数值模型和水槽实验领域的全球专家来应对这一挑战。我们将开发一个包含 PDC 矿床所有已知案例研究的数据库，确定描述和分析矿床的最可靠的方法，并开发一个指导下一代火山学家的框架。