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

不稳定性导致的火山崩塌可能导致特大型山体滑坡。这些形成的岩石雪崩可能会向外传播数十公里。这些事件的影响可能是毁灭性的，摧毁所有在他们的路径。这样的碎片雪崩在过去发生过多次。现场证据表明，在世界各地的火山周围都存在它们的沉积物。在某些情况下，这些大型山体滑坡可能伴随着火山喷发，但在其他时候，它们可能与火山活动没有明确的联系。因此，有不同类型的建筑物倒塌，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活动的变化。喷发行为的这种变化意味着，作为火山建设和毁灭周期的一部分，特定火山系统造成的危害类型可能会随着时间的推移而发生变化。与山崩和火山爆发有关的火山灾害目前是无法预测的。只有更详细地了解失败的原因，以及失败如何与这些大型滑坡的潜在危险联系起来，我们的预测能力才能提高。该项目旨在提高我们对火山碎屑雪崩是如何产生的，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害的全面了解。这些危害可以根据事件的时间、类型和规模进行评估。该项目还旨在将火山崩塌置于火山形成和破坏的过程中。这可以通过了解崩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。该项目将采取的方法是将对个别火山进行的大量详细研究所获得的现有数据与众所周知的碎片雪崩沉积物和火山崩塌所获得的新数据结合起来。我将评估这些数据的一般关系和模式有关的崩溃和雪崩过程的原因。选定的现场位于墨西哥和智利，那里有几个火山崩塌的例子。通过实地和化学测量，可以将碎片雪崩与坍塌火山的活动放在一个时间背景下。此外，化学数据可用于了解火山下方的岩浆如何随着时间的推移而变化，包括其储存条件，混合和上升。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崩溃的影响。现场和实验室的结果将通过计算和模型的应用得到加强，这些计算和模型显示了崩塌如何改变火山下方的应力和压力条件。因此，可以根据定量数据解释火山演变的变化，并可以更好地了解崩塌的规模和类型与火山活动变化之间的关系。这种方法对于了解个别火山的潜在类型和火山灾害的影响以及这些灾害如何随时间而变化非常重要。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害。这些危险可能包括泥石流行为的变化，或泥石流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.