Ballistic ejecta and eruption condition of the vulcanian explosion of Shinmoedake volcano, Kyushu, Japan on 1 February, 2011

Earth, Planets and Space

Table 2. Parameters used in the calculations of ballistic trajectories.

Atmospheric condition
Temperature at sea level	3.2	°C
Thermal lapse rate	6.6	°C/km
Speed of tailwind*	−2	m/s
Initial condition
Diameter of cubic-shaped block	0.5~1.1	m
Density of block	2100, 2400	kg/m³
Initial velocity	200~400	m/s
Ejection angle	10~70	°
Extent of zone of reduced drag	300	m
Elevation of takeoff point	1360	m (a.s.l.)
Elevation of landing point	945	m (a.s.l.)

*An averaged windspeed component at a direction of ballistic trajectories (250° clockwise from the north), calculated from wind profile data of JMA (12 m/s at 1048 m above sea level with a direction of 316°, and 9 m/s at 1504 m above sea level with a direction of 344°.)