火山噴煙ダイナミクス : 3次元数値シミュレーションモデルの発展と展開

抄録

The dimensions of volcanic plumes (i.e., heights and spreading area) are the key observable data to estimate the intensity of eruptions, and they are commonly used as an initial input for the calculation of tephra dispersal models. The relationship between these observed data and the eruption conditions such as mass eruption rate in the various atmospheric conditions has been investigated by analytical methods, simple numerical models, and large numerical simulations. In this paper, we have overviewed the recent progress of these numerical models. The latest three-dimensional fluid-dynamics model of eruption clouds has been tested from a viewpoint of comparison with the observed data of the Pinatubo 1991 eruption, the Shinmoe-dake 2011 eruption, and the Kelud 2014 eruption. To develop an operational model of eruption clouds, the effective values of the empirical constants used in the simple numerical models are estimated on the basis of the simulation results of the three-dimensional model. We propose the diagrams to quickly estimate the plume height when the eruption and atmospheric conditions (e.g., mass eruption rate and wind velocity) are given.