RAPID: Lethal pyroclastic density current (PDC) generation and transport at Fuego volcano

该快速研究响应奖（RAPID）将用于更好地了解2018年6月3日Fuego火山（危地马拉）的致命喷发，特别是导致死亡的火山碎屑密度流（PDC）。这些PDCs是如何发起的，是什么导致它们移动那么远，以及它们未来可能形成的条件是什么，都是人们知之甚少的问题。通过查看PDC存款，绘制它们并在野外研究它们的地层学，分析化学、岩石学和物理特征（密度和泡状度、粒度分布等），通过使用数值模型来了解它们的流动动力学，该团队希望能够告诉PDC材料来自哪里，以及它是如何破碎和运输的。他们还将研究火山爆发前和爆发期间的地球物理和地球化学监测数据，特别是来自当地地震网络和卫星遥感数据的数据，以确定火山爆发的其他方面（火山爆发强度和持续时间）的特征，并将火山中心的信息纳入这一背景。这些知识将提高我们对这种PDC形成的理解，特别是在Fuego等玄武岩火山，并可能与世界各地和美国的许多其他类似火山有关。该RAPID奖将支持野外工作制图，地层和相关联确定，基于无人机的矿床和潜在源区的摄影测量，以及PDC和气降火山灰矿床的样品收集。对实地采集的样品进行实验室分析的目的是确定PDC和火山灰成分的粒度分布、形状、密度和泡状度，以及地球化学（主要和微量元素分析）、岩相学和微观结构特征。现场和实验室工作将允许推断源过程（e. G.柱与上斜坡沉积物崩塌）的位置、体积和持续时间。将进行PDC在真实地形地貌（高分辨率DEM）上传播的数值建模（VolcFlow和Titan2D），受存款测绘和体积估计的约束，以及关于流动开始和传播的时间和持续时间的地球物理数据，以找到最佳拟合模型参数并推断流动动力学（例如：G.速度、质量流率、脉冲中的体积分配等）。这项研究将与危地马拉火山监测机构INSIVUMEH（国家火山、火山、气象和水文研究所）密切合作进行，研究结论将为INSIVUMEH监测和预测未来类似事件的工作提供大量信息，并可能使用类似模型纳入危险评估过程。研究结果也将有助于我们了解全球其他类似玄武岩火山的喷发过程（及其沉积物），特别是块灰流型PDC和相关沉积物的生成，以及与之相关的危害。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Rapid Research Response (RAPID) award will be used to better understand the deadly eruption at Fuego volcano (Guatemala) on June 3rd, 2018, and in particular the pyroclastic density currents (PDCs) that caused the fatalities. How those PDCs initiated, what caused them to move that far, and what could be the conditions under which they may form in the future, are all poorly understood issues. By looking at the PDCs deposit, mapping them and study their stratigraphy in the field, analyzing the the chemical, petrological, and physical characteristics (density and vesicularity, grain size distribution, etc.), and by using numerical models to understand their flowing dynamics, this team hopes to be able to tell where the PDCs material came from, and how it was fragmented and transported. They will also look at geophysical and geochemical monitoring data leading up and during the eruption, particularly from the local seismic network and satellite remote sensing data, to characterize other aspects of the eruption as well (eruption intensity and duration) and put the PDC information in that context. This knowledge will improve our understanding of the formation of this kind of PDCs, particularly at basaltic volcanoes like Fuego, and could be relevant to many other similar volcanoes worldwide and in the US.This RAPID award will support fieldwork mapping, stratigraphy and facies associations determination, UAV based photogrammetry of the deposits and potential source area, and sample collection of the PDC and airfall tephra deposits. Laboratory analysis of samples collected in the field will aim to characterize the grain size distribution, shape, density and vesicularity of PDCs and tephra components, as well as geochemical (major and trace element analysis) and petrographic and microtextural characteristics. Field and laboratory work will allow to infer the source process (e. g. column vs. upper slope deposits collapse) in terms of location, volume and duration. Numerical modeling (VolcFlow and Titan2D) of the PDCs propagation over realistic terrain topography (high resolution DEMs), constrained by deposit mapping and volume estimations, and the geophysical data on timing and duration on flow initiation and propagation will be conducted to find the best fit model parameters and infer the flow dynamics (e. g. velocity, mass flow rate, volume partition in pulses, etc.). The research will be conducted in close collaboration with Guatemalan volcano monitoring agency INSIVUMEH (Instituto Nacional de Sismologia, Vulcanologia, Meteorologia e Hidrologia) and the study's conclusions will be highly informative to INSIVUMEH's efforts to monitor and forecast similar events in the future, and the potential use of similar models to be incorporated in the hazard assessment process. The results will also be relevant to our understanding of eruptive processes (and their deposits) at other similar basaltic volcanoes worldwide, in particular the generation of block-and-ash flow type PDCs and associated deposits, and the hazards linked to them.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.