The quantification of the maximum runout, invaded area, volume, and total grain-size distribution (TGSD) of pyroclastic density currents (PDC) is a critically important task because such parameters represent the needed necessary input quantities for physical modeling and hazard assessment of PDCs. In this work, new and well-established methods for the quantification of these parameters are applied to a large stratigraphic dataset of three PDC units from two eruptions of Somma-Vesuvius (the AD 79 Pompeii and the AD 472 Pollena eruptions), representative of a large spectrum of transport and depositional processes. Maximum runout and invaded area are defined on the basis of the available volcanological and topographical constraints. The related uncertainties are evaluated with an expert judgment procedure, which considersed the different sectors of the volcano separately. Quite large uncertainty estimates of dispersal area (20–40%) may have important implications in terms of hazard assessment. The testing of different methods for estimating the volume (and mass) of a PDC deposit suggests that integration, over the invaded area, of thickness (and deposit density) data using the triangulated irregular network method can minimize and localize data extrapolation. Such calculations, however, bear an intrinsic additional uncertainty (at least 10% of the total PDC deposit) related to loss or new formation of fine material during transport (at least 10% of the total PDC deposit). Different interpolation methods for TGSD produce multimodal distributions, likely reflecting the different response of each grain size class to transport and deposition processes. These data, when integrated with information on the related co-ignimbrite deposits, can give a more accurate picture of the pyroclastic mixture feeding the current.

中文翻译：

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估计火山碎屑密度流沉积物的喷发参数和相关不确定性：来自 Somma-Vesuvius 的工作实例（意大利）

火山碎屑密度流 (PDC) 的最大跳动、侵入面积、体积和总粒度分布 (TGSD) 的量化是一项至关重要的任务，因为这些参数代表了 PDC 物理建模和危险评估所需的必要输入量. 在这项工作中，用于量化这些参数的新的和完善的方法被应用于来自 Somma-Vesuvius 两次喷发（公元 79 年庞贝和公元 472 年花粉火山喷发）的三个 PDC 单元的大型地层数据集，代表一个大范围的迁移和沉积过程。最大跳动和侵入区域是根据可用的火山学和地形限制来定义的。相关的不确定性通过专家判断程序进行评估，它分别考虑了火山的不同部分。相当大的扩散区域不确定性估计（20-40%）可能对危害评估具有重要意义。对估计 PDC 矿床体积（和质量）的不同方法的测试表明，使用不规则三角网方法对侵入区域的厚度（和矿床密度）数据进行整合可以最小化和定位数据外推。然而，此类计算具有与运输过程中细粒材料的损失或新形成（至少 PDC 沉积物总量的 10%）相关的固有附加不确定性（至少占 PDC 沉积物总量的 10%）。TGSD 的不同插值方法会产生多峰分布，这可能反映了每个晶粒尺寸等级对输运和沉积过程的不同响应。