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（PDCs）是火山爆发过程中形成的火山灰、气体和岩石的致命流动。它们可以以高达200公里/小时的速度行驶，内部温度高达1000摄氏度。它们对活火山中心附近不断增加的人口构成最大的火山危害之一，自公元1600年以来已造成9万多人死亡。了解这些水流是如何形成的，以及是什么控制了它们在时间和空间上的动态流动行为，对于改进我们用于灾害评估的预测模型至关重要。可悲的是，我们对PDCs的了解仍然有限，其发生继续导致悲剧。即使是相对较小的PDC也可以行驶数十公里，越过山丘和障碍，甚至越过水面。它们也非常具有破坏性，因为它们能够携带大的火山巨石，具有很强的研磨性，并且可以在广阔的区域内沉积存款数十米的沉积物。它们的行为受其内部动力学的控制，例如不同的火山灰和岩石颗粒如何相互作用，它们之间的气体压力，以及电流如何响应它所经过的地面。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，以便建立更好的灾害模拟。但是，我们无法看到PDC内部，因为它在喷发过程中流动，所以这些内部动力学对我们来说是未知的。当PDC流动时，它们会沉积存款火山灰和岩石，留下它们在岩石中通过的记录。这些沉积物的结构可能非常复杂，捕捉到了PDC随时间推移的变化。我们对PDC的理解主要是通过对这些沉积物的分析（事实上，它们并没有存款甚至侵蚀），但其中许多解释都是推测性的。尽管我们对PDCs的理解取得了重大进展，但我们对其物理过程的理解仍然存在根本性的差距，这些过程如何随时间和空间而变化，以及这如何导致其高流动性和破坏性行为。数值模型和水槽实验旨在填补这些研究空白。我们可以在不同尺度上模拟PDC的某些方面，以描述其基本物理学。我们希望建立计算机模型来模拟PDC，并预测它们在火山爆发期间可能流向何处。这将改变遭受火山灾害的社区的灾害评估。到目前为止，作为一个研究社区，我们还没有能够模拟这些电流的复杂性，我们从我们的实地研究中了解。我们还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。测试存款属性和形成它们的电流之间的关系的模型是至关重要的，但由于缺乏一致收集的、可比较的、量化的现场存款数据集来提供信息和验证，因此受到阻碍。该项目旨在汇集实地研究、数值模型和水槽实验方面的全球专家，以应对这一挑战。我们将开发一个PDC矿床所有已知案例研究的数据库，确定我们必须描述和分析矿床的最强大的方法，并开发一个框架，指导下一代火山学家。