Figure 2

Weibull model error surfaces produced by AshCalc for the 1992 Cerro Negro eruption. Graphs show different error functions (Relative Squared Error (RSE), lnRSE and $\mathrm{RSE}+\mathrm{lnRSE})$ plotted against λ and k over large and small ranges of the values. The minimum is in the region of $4.0\le \mathit{\lambda }\le 4.4,0.75\le \mathit{k}\le 0.85$. a) RSE error function–close to the minimum. b) RSE error function–larger view of parameter space. c) ln(RSE) error function–close to the minimum. d) ln(RSE) error function–larger view of parameter space. e) ln(RSE) + RSE error function–close to the minimum. f) ln(RSE) + RSE error function–larger view of parameter space.