In this paper, we present results of the reconstruction of the total grain size distribution (TGSD) of the material erupted during explosive volcanic eruptions at Campi Flegrei (Italy) considering all components (juvenile, lithic and crystal clasts). To date, the few TGSDs made available have been mostly reconstructed by assuming that the tephra deposits consisted of only one component. This simplification can introduce substantial bias in the interpretation of magma fragmentation mechanisms and significantly affect ash dispersion forecasts, since each tephra component has specific aerodynamic characteristics. By means of field investigations and laboratory analyses on samples collected from deposits of the Agnano-Monte Spina and Astroni eruptions, we reconstructed the TGSDs of juvenile, lithic and crystal components via the Voronoi tessellation method. Our results show how the systematic reconstruction of a TGSD, from the component-specific to the bulk TGSD, can provide important information on magma fragmentation mechanisms and wall-rock erosion processes. Results confirm that the bulk TGSD is the combination of the merging of different component subpopulations, according to their own TGSD, density and relative mass proportions. In addition, the integration of component analysis, TGSD and settling velocity data allowed characterization of the aerodynamic behaviour of each component at variable distances from the vent, which can be related to their own parent grain size distribution. The integration of new data from distal tephra deposits for the considered eruptions has thus allowed a reassessment of the erupted volumes of eruptions considered in this research, which are now 3.17 and 0.63 km 3 , for Agnano-Monte Spina and Astroni, respectively.

中文翻译：

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沉降沉积物组分的总粒度分布及其对岩浆破碎机制的影响：来自 Campi Flegrei 火山口（意大利）的例子

在本文中，我们介绍了在 Campi Flegrei（意大利）爆发性火山喷发期间喷发的材料的总粒度分布 (TGSD) 的重建结果，其中考虑了所有成分（幼体、岩屑和晶体碎屑）。迄今为止，少数可用的 TGSD 主要是通过假设火山灰沉积物仅由一种成分组成来重建的。这种简化可能会给岩浆破碎机制的解释带来重大偏差，并显着影响灰烬扩散预测，因为每个火山灰成分都具有特定的空气动力学特性。通过对从 Agnano-Monte Spina 和 Astroni 火山喷发沉积物中收集的样本进行实地调查和实验室分析，我们重建了青少年、通过 Voronoi 曲面细分方法的石质和晶体组件。我们的结果表明，从特定组件到整体 TGSD，TGSD 的系统重建如何能够提供有关岩浆破碎机制和围岩侵蚀过程的重要信息。结果证实，大块 TGSD 是不同组分亚群的合并，根据它们自己的 TGSD、密度和相对质量比例。此外，组件分析、TGSD 和沉降速度数据的集成允许表征每个组件在距通风口可变距离处的空气动力学行为，这可能与它们自己的母体晶粒尺寸分布有关。