[S-VC50_2PO1] Dynamics of volcanic eruptions and igneous activities

[SVC50-P01] Tephra-Fall Predictions with the JMA Regional Atmospheric Transport Model for the 1914 Eruption at Sakurajima Volcano

*Toshiki SHIMBORI¹, Shomei SHIRATO², Yoshihiko HASEGAWA³, Akihiro HASHIMOTO¹, Akimichi TAKAGI¹, Tetsuya YAMAMOTO¹, Akira YAMAMOTO¹ (1.Meteorological Research Institute, 2.Kagoshima Local Meteorological Office, 3.Japan Meteorological Agency)

Keywords:Atmospheric Transport Model, volcanic-ash dispersal, tephra fall, Volcanic Ash Fall Forecast, Sakurajima volcano, 1914

A hundred years ago, the largest eruption in 20th century Japan, i.e. the Sakurajima Taisho Eruption occurred on 12 January 1914. With this eruption, tephra-falls were observed large-area in Japan from Kyushu to Tohoku region (Hasegawa, 1914; Omori, 1916). For such large-scale eruptions, the Meteorological Research Institute (MRI) is going to do new research project of the tephra-fall predictions with the JMA Regional Atmospheric Transport Model (JMA-RATM) from this year. The research will lead to the improvement of the Volcanic Ash Fall Forecasts (VAFFs) of the Japan Meteorological Agency (JMA). For the purpose of investigating the predictability of the current JMA-RATM against large-scale eruptions, predictions of volcanic-ash dispersion and tephra-fall for the Sakurajima Taisho Eruption were carried out. The initial values which are the total volume (ash and pumice) of 6×10⁸ m³, the plume height of 3000-18000 m and the eruption duration of 38 hours are assumed based on Yamashina (1999), Yasui et al. (2006), Iguchi (2014) and so on. The input GPVs are the JMA Mesoscale Analysis after 28 March 2013. The forecast time by the JMA-RATM is 72 hours from starting time. Results of the calculations indicate that, under the assumption of the ash-density of 1 g/cm³, the predictions of tephra-fall depths are over 1 m in Sakurajima Island for weak-wind weather condition, several 10 cm at Kagoshima City for easterly wind in summertime, and of the order of 0.1-1 mm at Osaka, Nagoya and Tokyo Metropolitan area for southwesterly wind field. In the atmosphere, dispersions of volcanic-ash up to Tohoku and Hokkaido region are also predicted at the same forecast time. In the presentation, from the results of volcanic-ash dispersion and tephra-fall prediction, the predictability and problems of the current JMA-RATM for large-scale eruptions will be reported.ReferencesHasegawa, K., 1914: Summary report on the Sakurajima eruption. Geophys. Rev., 170, Central Meteorological Observatory, Tokyo, 1-16. Iguchi, M., 2014: The centennial anniversary of the Taisho Eruption. Lecture note, Ceremony for the Sakurajima Taisho Eruption 100th Anniversary. Omori, F., 1916: Accumulation and transportation of ashes thrown out during the Sakura-jima eruptions of 1914: The Sakura-jima eruptions and earthquakes II. Bull. Imperial Earthq. Invest. Comm., 8, 113-133. Yamashina, K., 1999: Volcanic cloud height of the 1914 eruption at Sakurajima volcano - Discussions on documentary records and photographs. Bull. Volcanol. Soc. Japan, 44, 71-82. Yasui, M., M. Takahashi, K. Ishihara and D. Miki, 2006: Records on the 1914-1915 eruption of Sakurajima volcano, Japan. Proc. Inst. Nat. Sci., Nihon Univ., 41, 75-107.