[S-VC52_28AM1] 火山防災の基礎と応用

[SVC52-02] 降灰ハザード評価における代表気象条件の選定への考察

*服部 康男¹、須藤 仁¹、郷 祐美子²、土志田 潔¹、平口 博丸¹、石原 修二² (1.電力中央研究所、2.電力計算センター)

キーワード：火山灰輸送-堆積モデル, 長期気象再解析, 極値, 人工ニューラルネットワーク, 移流・拡散, 数値シミュレーション

Estimation of ash concentration and deposition is of practical interest in evaluation of volcanic ash risk on critical infrastructure (e.g. Wardman et al. 2012). For estimating ash concentration and deposition, numerical simulations with an ash transport- and deposition-model have become a powerful tool (e.g. Folch 2012). However, the setup of meteorological conditions, which mainly control the ash transport- and deposition- processes in the atmosphere and on the ground, has not been discussed in details.In the present study, we examine the estimation of ground deposition for a real test case, a volcanic ash hazard in Kanto-area for an eruption at Mt. Fuji, with various meteorological conditions by using an ash transport- and deposition-model, fall3d. The meteorological conditions are generated with the 53 years reanalysis meteorological dataset, CRIEPI-RCM-Era2, which has a temporal- and spatial resolutions of 1 hr and 5 km; the typical and extreme conditions were sampled by using Gumbel plot and an artificial neural network technique.The ash deposition is invariably limited to the west area of Mt. Fuji, even with the typical wind conditions on summer, while the isopach of ground deposition depicted various distributions, which strongly depends on meteorological conditions. This implies that the concentric circular distribution must not be realistic. Also, a long-term eruption, such as the Hoei eruption during stage3, yields large deposition area due to the diurnal variations of wind direction, suggesting that the attention to the differences between diurnal variation and fluctuations of wind direction on evaluating of volcanic ash risk is vital.More details will be presented in the presentation, and we believe that our study must be helpful to develop the numerical simulations for evaluation of volcanic ash risk.