Journal of Disaster Research
Online ISSN : 1883-8030
Print ISSN : 1881-2473
ISSN-L : 1881-2473
Special Issue on Future Volcano Research in Japan: Integrated Program for Next-Generation Volcano Research
Numerical Simulations of Dome-Collapse Pyroclastic Density Currents Using faSavageHutterFOAM: Application to the 3 June 1991 Eruption of Unzen Volcano, Japan
Hiroyuki A. Shimizu
Author information

2022 Volume 17 Issue 5 Pages 768-778


Pyroclastic density currents (PDCs) are one of the most dangerous but least understood phenomena of volcanic eruptions. An open-source numerical depth-averaged model of dense granular currents controlled by physical processes such as energy dissipation, basal deposition, and erosion (faSavageHutterFOAM) was applied to investigate the basal concentrated region of a dome-collapse PDC generated on June 3, 1991 at Unzen volcano (Japan) to assess the effects of the physical processes (and their interplay) on the flow dynamics and run-out area of the PDC. Numerical simulations show that energy dissipation process decreases the flow velocity and increases the basal deposition rate, which reduces the run-out distance. The simulations also reveal that erosion process during flow propagation decreases the flow velocity and increases the run-out distance. The numerical results are sensitive to the parameters of energy dissipation (dry friction coefficient μ and collisional or turbulent friction coefficient χ) and erosion (specific erosion energy eb). The results are fitted to field data for run-out distance and flow velocity when μ is between 0.01 and 0.1 with χ∼103 m-1 s-2 (or when χ is between 104 and 105 m-1 s-2 with μ∼0.2) and eb∼102 m2 s-2. The estimated value of eb suggests that re-entrainment of deposit mass played an important role in controlling the flow dynamics and run-out area of the PDC. The estimated values of μ and χ are correlated, but the estimation of these parameters might be improved by further constraints from field data. The presented results serve as a basis to make further quantitative estimations of the model parameters (μ, χ, and eb) for applying the faSavageHutterFOAM model to hazard assessments of PDCs.

Content from these authors

This article cannot obtain the latest cited-by information.

© 2022 Fuji Technology Press Ltd.

This article is licensed under a Creative Commons [Attribution-NoDerivatives 4.0 International] license (
The journal is fully Open Access under Creative Commons licenses and all articles are free to access at JDR official website.
Previous article Next article