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Table 1 Estimated volume and mass of Ontake eruption on 27 September 2014

From: Reconstruction of a phreatic eruption on 27 September 2014 at Ontake volcano, central Japan, based on proximal pyroclastic density current and fallout deposits

Event date Methoda Caseb Volumec (×106 m3) Mass (×109 kg)
Fallout deposit and proximal pyroclastic density current deposit
 27 September a 1 0.77–1.1 (0.31–0.46) 0.77–1.1
 27 September a 2 0.67–1.3 (0.27–0.52) 0.67–1.3
 27 September b 1 0.70–1.2 (0.28–0.49) 0.70–1.2
 27 September b 2 0.77–1.4 (0.31–0.54) 0.77–1.4
 27 September c 1 0.63–1.4 (0.25–0.56) 0.63–1.4
 27 September c 2 0.74–1.2 (0.30–0.48) 0.74–1.2
Event date Methodd   Volumec (×106 m3) Mass (×109 kg)
Pyroclastic density current deposit in S and W slopes
 27 September d Max 0.072 (0.029) 0.072
 27 September d Min 0.036 (0.015) 0.036
 27 September e Max 0.03 (0.01) 0.03
 27 September e Min 0.005 (0.002) 0.005
  1. aMethod for fallout: (a) integrating log[mass per unit area (kg/m2)] versus log[area (m2)], (b) exponential fitting for log[thickness (m)] versus [area (m2)]1/2, (c) Weibull fitting for log[mass per unit area (kg/m2)] versus [area (m2)]1/2
  2. bCase: Cases 1 and 2 represent calculations that include and exclude proximal isopach data, respectively
  3. cVolume in parentheses is DRE (dense rock equivalence) value
  4. dMethod for PDC: (d) 2 cm and 1 cm in average thickness were assumed for maximum and minimum cases, respectively, (e) Scaling analyses using a depth-averaged gravity flow model