Table 1 Vegetation recovery indices used to document the recovery of vegetation over time after the eruption. All NDVI values used in these indices are NDVI_corr values

Lack of greenness (LG)

\( LG(t)=NDV{I}_{post}(t)-NDV{I}_{pre}^{*} \)

Gouveia et al. (2010)

Change in NDVI (T_c)

\( {T}_c(t)=\frac{NDV{I}_{pre}^{*}-NDV{I}_{post}(t)}{NDV{I}_{pre}^{*}} \)

Lu et al. (2012)

Stand Regeneration Index (SRI)

\( SRI(t)=\frac{NDV{I}_{post}(t)}{NDV{I}_{pre}^{*}} \)

Hope et al. (2012)

Vegetation Recovery Rate (VRR)

\( VRR(t)=\frac{NDV{I}_{post}(t)-NDV{I}_{erup}}{NDV{I}_{pre}^{*}-NDV{I}_{erup}} \)

Chou et al. (2009); Lu et al. (2012)

Ash Recovery Index (ARI)

\( ARI(t)=\frac{NDV{I}_{post}(t)-NDV{I}_{lowest}}{NDV{I}_{\max pre}-NDV{I}_{lowest}} \)

Adapted from Hope et al. (2012)