Numerical Simulation of Volcanic Ash Plume Dispersal from Kuchinoerabujima on 29 May 2015

抄録

In this study, airborne ash dispersal from the eruption of Kuchinoerabujima Volcano in Japan on 29 May 2015 is simulated using the volcanic ash tracking PUFF model. A major eruption occurred at 9:59 am local time (0:59 UTC), and the ash plume reached 9 km above the ground. According to MTSAT-2 satellite monitoring, the ash plume with a mushroom-shaped distribution drifted in the east-southeast direction. The observed ash fallout over Yakushima Island is in the order of 100 g/m2. Using this observational fact, we estimated that a particle in the numerical model represents 60 tons of ash mass. Based on this number, total emissions are estimated to be 600,000 tons for this event. The result suggests that the ash concentration in the air can also be estimated by this method. According to the aviation safety report, an ash density of 4 mg/m3 and above is considered as a danger zone for commercial airliners. The PUFF model simulation shows that the core region of the plume front at 9 km in height indicates 100 mg/m3 of airborne ash density even for the plume 250 km from the erupting volcano. The satellite images show the exact location of the ash plume. The PUFF model simulation can therefore estimate the airborne ash density over a much wider diffused area to identify the danger zone for aircraft.