Fig. 4

a Distribution of Unit A (PDC deposits) and thickness data near the summit area (unit is cm). Broken lines and arrows indicate representative PDC lobes and their directions, respectively. b Isopach map of total (fallout and PDC) deposits for the proximal area (unit is cm) and c isomass map for the distal area (unit is g/m2). Distal data were provided by—the Joint Research Team for Ash Fall from the Ontake 2014 Eruption (2015)