Topographic Controls on the Generation of Elutriated Ash Clouds: II. Nature and Dynamics of Pyroclastic Density Currents

9725361 Bursik火山碎屑流或nues ardentes可能是最具破坏性的火山现象，但对火山现象的了解却最少。由于它们的破坏性，几乎不可能直接观察到；然而，它们留下的沉积物已被证明极难解释。所提议的研究的主要目的是确定在特定的、良好约束的情况下，火山碎屑流中的活动流动条件与由此产生的沉积物之间的联系。因为我们可能能够确定流中发生了什么，所以结果可能对危害分析中的流模拟和火山危害评估具有重要的影响。拟议的工作将分实验、理论和实地工作三个阶段进行。这项工作将首先在实验室中使用专门为这些研究目的而设计的特殊设备，在受到良好约束的流动条件下仔细地进行沉积。理论建模将通过推广观察到的流动力学来扩展实验的适用范围。实验室和理论结果将通过对火山碎屑流沉积物的某些诊断部分进行仔细的沉积学分析来检验，特别是对具有一些活动流动条件信息的现代沉积物。

9725361 Bursik Pyroclastic flows or nuees ardentes are perhaps the most destructive, yet most poorly understood of volcanic phenomena. Because of their destructiveness, they are virtually impossible to observe directly; yet they leave deposits that have proven extremely difficult to interpret. The primary objective of the proposed research is to determine in specific, well-constrained situations the link between active flow conditions in pyroclastic flows and the resulting deposits. Because we may be able to determine what is happening within the flows, the results could have important ramifications for the simulation of flows in hazards analysis, and for volcanic hazards assessment. The proposed work will procede with experimental, theoretical and fieldwork phases. The work will begin by carefully making deposits in the laboratory under well-constrained flow conditions, using special facilities designed only for the purpose of these studies. Theoretical modeling will extend the range of applicability of the experiments by generalizing the observed flow mechanics. Laboratory and theoretical results will be tested by careful sedimentological analysis of certain diagnostic portions of pyroclastic flow deposits, especially modern deposits for which there is some information on active flow conditions.