SGER: 1998 Volcan Casita Mudflow, Nicaragua

9901694 Sheridan该SGER奖旨在为一名火山学家在十年来与火山有关的最严重灾难之一的现场提供快速反应。与哈罗德飓风相关的暴雨充斥了尼加拉瓜伏尔坎卡西塔的山顶火山口，显然导致火山口墙的裂缝迅速溢出。由此产生的饱和水分的火山碎屑雪崩席卷了山下，包围了几个村庄。像这样的火山泥石流(拉哈尔)对世界各地的人们构成了重大危险，但关于触发机制(S)、流动特征和物质性质的详细信息通常只能从史前或古代沉积中获得。与尼加拉瓜大学地球物理研究所合作，将开展为期约一周的实地活动，重点是测量和采样新鲜的岩浆沉积物，收集关于岩浆开始和流动的目击者描述，以及对源头区域和流出模式进行空中观测。样本和其他数据将在从野外返回后进行评估，这些数据将用于构建沃尔坎卡西塔泥石流开始的模型。原始数据和观测结果，以及所得出的模型，将有助于更好地了解导致熔岩形成和侵位的机制，并将有助于评估和减轻其他区域与这些现象有关的风险。

9901694SheridanThis SGER award is aimed at rapid response placement of a volcanologist on site at one of the worst volcano-related disasters of the decade. Torrential rains associated with hurricane Harold filled the summit crater of Volcan Casita, Nicaragua apparently leading to rapid overflow through a breach in the crater wall. The resulting avalanche of water-saturated volcanic debris swept down the mountain enveloping several villages. Volcanic mudflows (lahars) such as this pose major hazards to populations throughout the world, yet details regarding the triggering mechanism(s), flow characteristics, and material properties generally only are available from pre-historic or ancient deposits. An approximate one-week field campaign, in collaboration with the Geophysical Institute of the University of Nicaragua, will focus on measurements and sampling of fresh lahar deposits, collection of eye-witness accounts of the initiation and flow, and aerial observations of the source area and outflow pattern. Samples and other data will be evaluated upon return from the field, and these data will be used to construct a model for the inception of the Volcan Casita mudflow. The primary data and observations, together with the derived model, will contribute to a better understanding of the mechanisms leading to lahar formation and emplacement, and will assist in assessing and mitigating the risks associated with these phenomena in other regions.