Fig. 3. Histograms of the DEM difference for selected areas: (a) a flat area on the pre-1964 lava flow, (b) a flat area on the 1964 lava flow, (c) an area on the
southwestern flank of the volcano, (d) the glaciated summit area of the volcano, (e) the lower part of the 1991– 1992 lava flow (elevation < 600 m), and (f) the
upper part of the 1991–1992 lava flow (elevation >600 m). The boxes in Fig. 1(b) outline the areas corresponding to the histograms in (a)– (d).