The term “ignimbrite” probably encompasses the one of the largest ranges of deposit types on Earth, associated with the partial to total collapse of explosive eruption columns feeding pyroclastic density currents. Surprisingly, there is no quantified classification scheme for ignimbrite types, as there is for fallout deposits, and this is a remarkable deficiency of modern volcanology. This has so far prevented the identification of standardized descriptors for ignimbrites and the improvement of methods for the documentation of their characteristics, such as happened for fallout deposits, building on the classification scheme proposed by Walker in 1973. Despite some earlier attempts, ignimbrite types do not conform to eruption style nomenclature. In this paper, we explore and discuss descriptors for a classification scheme based on the correlation of runout, areal extent, aspect ratio and volume from a compiled database comprising 92 ignimbrites, which then allows current understanding of pyroclastic flow dynamics to be considered. We refer to single ignimbrite outflow units, i.e. emplaced without significant breaks in their sedimentation, in extra-caldera settings and forming individual cooling units, irrespective of internal lithofacies architecture. Our main finding is that ignimbrites show remarkable power-law relationship between dispersal area/equivalent runout and bulk volume. Runout is directly related to increasing mass flow rate feeding the pyroclastic current. Volume is related to the magnitude of the flow event. We therefore propose that by measuring first order field observables such as bulk volume and dispersal area provides the opportunity to evaluate magnitude and intensity of related pyroclastic currents and, for large eruptions dominated by ignimbrites, of the eruption. Based on the relationships identified we propose that ignimbrites that originated from the collapse of single point-source eruption columns, usually smaller than 1 km³, are named “Vulcanian ignimbrites” and “Plinian ignimbrites” depending on the style of the eruption they are associated with. Larger ignimbrites that originated from caldera-forming eruptions along ring-fault fissure vents should be regarded as related to a separate eruption style - with respect to the common Hawaiian-Plinian trend -, where the effect of increased mass flow rate due to ring-fissure vents is dominant and controls the dynamics of the resulting collapsing fountains and pyroclastic flows, irrespective of the kind of eruption style that preceded the onset of the caldera collapse. These are named “caldera-forming ignimbrites” and are further subdivided into small, intermediate, large and super, based on their increasing erupted volume.

术语“点燃”可能包括地球上最大范围的沉积物类型之一，与供给火山碎屑密度流的爆炸性喷发柱的部分或全部坍塌有关。令人惊讶的是，对于熔凝灰岩类型没有量化的分类方案，就像沉降沉积物一样，这是现代火山学的一个显着缺陷。到目前为止，这阻碍了对凝灰岩的标准化描述符的识别和改进记录其特征的方法，例如在沃克于 1973 年提出的分类方案的基础上发生的沉降沉积物。 尽管有一些早期的尝试，但凝灰岩类型确实存在不符合喷发式命名法。在本文中，我们探索和讨论了分类方案的描述符，这些描述符基于跳动、面积范围、纵横比和体积的相关性，这些数据来自一个包含 92 个熔结岩的编译数据库，然后允许考虑当前对火山碎屑流动力学的理解。我们指的是单个 ignbrite 流出单元，即在它们的沉积中没有显着中断的位置，在火山口外环境中并形成单独的冷却单元，而不管内部岩相结构。我们的主要发现是，凝灰岩在扩散面积/等效跳动和体积之间显示出显着的幂律关系。跳动与增加火山碎屑流的质量流量直接相关。体积与流动事件的大小有关。因此，我们建议通过测量一阶场可观测值，例如体积和扩散面积，提供了评估相关火山碎屑流的大小和强度的机会，以及对于以结冰凝灰岩为主的大喷发的喷发。根据已确定的关系，我们提出源自单点源喷发柱坍塌的 ignbrites，通常小于 1 公里³，根据与它们相关的喷发类型被命名为“Vulcanian ignimbrites”和“Plinian ignimbrites”。源自沿环断层裂隙喷口的火山口形成喷发的较大的火山灰岩应被视为与单独的喷发类型有关 - 相对于常见的夏威夷 - 普林尼亚趋势 - 由于环裂导致质量流量增加的影响喷口占主导地位，并控制由此产生的坍塌喷泉和火山碎屑流的动力学，而不管火山口坍塌发生之前的喷发类型如何。 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 这些被称为“形成火山口的火山灰岩”，并根据它们不断增加的喷发量进一步细分为小型、中型、大型和超大型。