2015 年 30 巻 3 号 p. 168-176
Abstract In various hazards caused by volcanic eruptions, tephra particles (including volcanic ash and lapilli) transported by atmosphere affect widespread areas distant from the volcano. To provide information about predicted ash fall quantity and lapilli fall area for residents, the Japan Meteorological Agency (JMA) renewed the Volcanic Ash Fall Forecast (VAFF) in March 2015. Focusing on relatively large ash and lapilli particles, the VAFFs have operationally used short-term falling simulations based on the JMA Regional Atmospheric Transport Model (JMA-RATM). In this article, grain-size distribution and settling velocity of tephra which have an especially large impact on the accuracy of the fall simulations are described. We show an example of the RATM simulation for the 2011 eruption of Shinmoe-dake volcano and discuss the future work on the modeling and predicting of tephra transport.
