Volcanic flank collapse: diversity of behaviour, hazard generation and controls on volcano evolution

不稳定导致的火山崩塌可能会导致极大的山体滑坡。这些岩石形成了雪崩，可以向外移动数十公里。这类事件的影响可能是毁灭性的，摧毁了他们前进道路上的一切。这样的碎片雪崩在过去已经发生过多次。现场证据表明，它们在世界各地的火山周围都有矿藏。在某些情况下，这些大型山体滑坡可能会伴随喷发，但在其他情况下，它们可能会发生，而与火山活动没有明确的联系。因此，有不同类型的建筑物坍塌可能会产生碎片雪崩。除了产生碎片雪崩外，火山的一部分坍塌还可能导致火山本身随后的活动发生变化。火山喷发行为的这种变化意味着，作为火山建造和破坏周期的一部分，特定火山系统构成的危险类型可能会随着时间的推移而变化。与山体滑坡和火山喷发有关的火山灾害目前是不可预测的。只有更详细地了解失败的原因，以及失败与这些大型山体滑坡的潜在危险之间的关系，才能提高我们的预测能力。该项目旨在提高我们对火山碎片雪崩是如何产生的，以及不同原因或类型的崩塌如何导致雪崩造成的一系列危险的全面了解。可以根据事件的时间、风格和规模来评估这些危险。该项目还旨在将火山坍塌置于火山形成和破坏过程中。这可以通过了解坍塌如何影响火山下储存的岩浆，从而影响后来的火山活动和发展来实现。这些关系是理解火山作用的基础。该项目将采取的办法是将对个别火山的大量详细研究的现有数据与著名的碎片雪崩沉积和火山崩塌的新数据结合起来。我将评估这些数据，以寻找与崩塌和雪崩过程的原因有关的一般关系和模式。选定的现场地点在墨西哥和智利，那里有几个火山崩塌的例子暴露得很好。通过现场和化学测量，碎片雪崩可以与坍塌火山的活动放在一个时间背景下。此外，化学数据可以用来了解火山下面的岩浆如何随着时间的推移而变化，就其存储条件、混合和上升而言。因此，这些数据提供了有关火山随时间演变的信息，以及这种演变如何受到坍塌的影响。现场和实验室的结果将通过计算和模型的应用得到加强，这些计算和模型表明坍塌如何改变火山下方的应力和压力条件。因此，可以根据定量数据来解释火山演化的变化，可以更好地理解崩塌的大小和类型与火山行为变化之间的关系。这种方法对于了解个别火山的潜在火山灾害类型和影响，以及这些类型和影响随时间的不同是很重要的。这项工作的进一步发展将是应用这些发现来了解碎片雪崩的行为及其在不同环境中的相关危险。这种危险可能包括碎片雪崩流动行为的改变，或碎片雪崩与水相互作用时产生的海啸。

The collapse of volcanoes, resulting from instability, can lead to extremely large landslides. These form avalanches of rock that may travel outwards for tens of kilometres. The impacts of such events can be devastating, destroying all in their path. Such debris avalanches have occurred many times in the past. Field evidence indicates the presence of their deposits around volcanoes worldwide. In some cases, these large landslides may be accompanied by eruption, but at other times, they may occur without a clear link to volcanic activity. Thus, there are different types of edifice collapse that may generate debris avalanches. In addition to generating debris avalanches, the collapse of a portion of a volcano can lead to changes in the subsequent activity of the volcano itself. This change in eruptive behaviour results means that the types of hazard posed by a particular volcanic system may switch through time, as part of a cycle of volcano construction and destruction. Volcanic hazards, related both to landslides and eruption, are at present unpredictable. Only by understanding in more detail the causes of failure, and how failure relates to the hazardous potential of these large landslides, can our forecasting capacity be improved. This project aims to improve our overall understanding of how volcanic debris avalanches are generated, and how different causes or types of collapse result in a range of hazards posed by avalanches. These hazards can be assessed in terms of the timing, style and size of events. The project also aims to place the collapse of volcanoes within the process of volcano formation and destruction. This can be done through understanding how collapse affects magma stored beneath the volcano, and thereby influences later volcanic activity and development. These relationships are fundamental to understanding volcanism. The approach this project will take is to incorporate existing data, from numerous detailed studies of individual volcanoes, with new data from well-known debris avalanche deposits and volcano collapses. I will assess these data for general relationships and patterns relating to the causes of collapse and avalanche processes. The selected field sites are in Mexico and Chile, where several examples of volcanic collapses are well exposed. By taking field-based and chemical measurements, debris avalanches can be placed in a time-context with activity at the collapsed volcano. Additionally, chemical data can be used to understand how magma beneath the volcano has changed through time, in terms of its storage conditions, mixing and ascent. Such data therefore provide information relating to the evolution of volcanoes through time, and how this evolution is impacted by collapse. The field and laboratory results will be strengthened by the application of calculations and models that show how collapse alters the stress and pressure conditions beneath volcanoes. Hence, changes in volcano evolution can be interpreted in light of quantitative data, and relationships between sizes and types of collapse and changes in volcanic behaviour can be better understood. This approach is important for understanding the potential types and impacts of volcanic hazards at individual volcanoes, and how these may differ through time. Further developments of this work will be to apply these finding to understand the behaviour of debris avalanches and their associated hazards in different environments. Such hazards may include changes in debris avalanche flow behaviour, or tsunami generation when debris avalanches interact with water.