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

火山的崩塌，由于不稳定，可以导致极大的滑坡。这些形成的岩石雪崩可能向外移动数十公里。这类事件的影响可能是毁灭性的，沿途的一切都会被摧毁。这样的碎片雪崩在过去发生过很多次。实地证据表明，它们的沉积物存在于世界各地的火山周围。在某些情况下，这些大型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，有不同类型的大厦倒塌可能产生碎片雪崩。除了产生碎片雪崩外，火山部分的崩塌还会导致火山本身随后活动的变化。这种喷发行为的变化意味着，特定火山系统造成的危险类型可能会随着时间的推移而改变，这是火山形成和破坏周期的一部分。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。只有更详细地了解破坏的原因，以及破坏与这些大型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屑雪崩如何产生的整体理解，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。这些危险可以根据事件发生的时间、类型和规模进行评估。该项目还旨在将火山的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。该项目将采用的方法是将现有数据（来自对单个火山的大量详细研究）与来自众所周知的碎片雪崩沉积物和火山崩塌的新数据结合起来。我将对这些数据进行评估，找出与崩塌和雪崩过程的原因有关的一般关系和模式。选定的实地地点在墨西哥和智利，那里有几个火山崩塌的例子很好地暴露出来。通过实地测量和化学测量，可以将碎片雪崩置于崩塌火山活动的时间背景中。此外，化学数据可以用来了解火山下的岩浆是如何随着时间的推移而变化的，包括它的储存条件、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塌的影响。实地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的应力和压力条件。因此，火山演化的变化可以根据定量数据来解释，并且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。这种方法对于了解单个火山的潜在类型和火山危害的影响以及这些危害随时间的变化是很重要的。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害。这些危险可能包括碎片雪崩流动行为的改变，或者当碎片雪崩与水相互作用时产生海啸。

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.