Modelled dispersion parameters

Explored range

TamboraF2^{a}


Tephra mass (10^{12} kg)

0.11.5

1.2

Tephra volume (km^{3})

0.11.5

1.0

Tephra volume DRE (km^{3})^{b}

0.11.5

0.4

Duration (hours)

02.8

2.8^{c}

MER (10^{8} kg/s)

110

1.3

TGSDmaxima (in Ø units)

08

8

Column height (km)

3043

30

Suzuki coefficients A (−)^{d}

14

4

Density of aggregates (kg/m3)^{e}

100600

300

Diameter of aggregates (in Ø units)^{e}

23

2.5

Average deposit density (kg/m3)^{f}

Assumed

1100

Aida Indices K/k (−)^{g}

Calculated

0.98/1.29


^{a}These scenarios are the combination of meteorological and volcanological parameters that best reproduce the observed deposits of the Tambora F2 Plinian fall layer

^{b}A density value of 2650 kg/m^{3} (trachyandesite) was used to convert into DRE volume

^{c}Short eruption duration interpreted to be the result of high magma discharge rate (Sigurdsson and Carey, 1989)

^{d}The eruption source is described in a purely empirical way in order to reproduce the optimal geometrical shape of the deposits using the Suzuki distribution (in this instance the eruption column acts as a vertical line source)

^{e}Aggregation is accounted for using a model similar to that of Cornell et al. (1983) assuming that 50 % of the 63–44 μm (4–4.5Ø) ash, 75 % of the 44–31 μm (4.55Ø) ash and 95 % of the sub31 μm (<5Ø) ash fell as aggregated particles

^{f}This density value was used to convert deposit thickness, in mass loading and to calculate total tephra volume

^{g}Reliability of the bestfit results are shown by the Aida indices (Aida, 1978) for the geometric average (K) and geometric standard deviation (k)