Pyroclastic currents are described as gravity currents, and the classic conceptual model gives a first-order importance to the density of such currents. This directs quantitative models to assume specific flow structures (shallow water or equilibrium turbulent boundary layer), which may apply to restricted volcanic areas independently of source dynamics or may correspond to source dynamics separate from topographic interaction. The recent introduction of two end-members of pyroclastic currents, inertial and forced, is further developed here, leading to a global conceptual model in which source dynamics and topographic interaction are both taken into account. The concept of energy facies is defined here as the ensemble of the first-order indicators of pyroclastic currents (topological aspect ratio, competence ratio and emplacement temperature) that are proxies of the energy of such currents. Nine energy facies are introduced with general applicability and with the goal to globally characterize pyroclastic currents from vent to deposit.

中文翻译：

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能量相：从喷口到沉积物的火山碎屑流的全球视图

火山碎屑流被描述为重力流，经典的概念模型对这种流的密度给出了第一顺序的重要性。这指导定量模型假设特定的流动结构（浅水或平衡湍流边界层），这可能适用于独立于源动力学的受限火山区域，或者可能对应于与地形相互作用分开的源动力学。最近引入的两个末端成员的火山碎屑流，惯性和强迫，在这里得到了进一步发展，导致了一个全球概念模型，其中源动力学和地形相互作用都被考虑在内。能量相的概念在这里定义为火山碎屑流的一阶指标（拓扑纵横比、能力比和就位温度）的集合，它们是这种流能量的代理。介绍了具有普遍适用性的九种能量相，旨在全球表征从喷口到沉积物的火山碎屑流。