Sensitivity analysis and uncertainty estimation for tephra dispersal models

[1] Sensitivity analysis and uncertainty estimation are crucial to the validation and calibration of numerical models. In this paper we present the application of sensitivity analyses, parameter estimations and Monte-Carlo uncertainty analyses on TEPHRA, an advection-diffusion model for the description of particle dispersion and sedimentation from volcanic plumes. The model and the related sensitivity analysis are tested on two sub-plinian eruptions: the 22 July 1998 eruption of Etna volcano (Italy) and the 17 June 1996 eruption of Ruapehu volcano (New Zealand). Sensitivity analyses are key to (1) constrain crucial eruption parameters (e.g., total erupted mass) (2) reduce the number of variables by eliminating non-influential parameters (e.g., particle density) and (3) investigate the interactions among all input parameters (plume height, total grain-size distribution, diffusion coefficient, fall-time threshold and mass-distribution parameter). For the two test cases, we found that the total erupted mass significantly affects the model outputs and, therefore, it can be accurately estimated from field data of the fallout deposit, whereas the particle density can be fixed at its nominal value because it has negligible effects on the model predictions.

[1]  C. Bonadonna,et al.  Numerical modelling of tephra fallout associated with dome collapses and Vulcanian explosions: application to hazard assessment on Montserrat , 2002, Geological Society, London, Memoirs.

[2]  William I. Rose,et al.  Quantitative shape measurements of distal volcanic ash , 2003 .

[3]  Keith Beven,et al.  The future of distributed models: model calibration and uncertainty prediction. , 1992 .

[4]  R. S. J. Sparks,et al.  The dimensions and dynamics of volcanic eruption columns , 1986 .

[5]  Marcus I. Bursik,et al.  Sedimentation from turbulent jets and plumes , 1996 .

[6]  Arnau Folch,et al.  A three-dimensional Eulerian model for transport and deposition of volcanic ashes , 2006 .

[7]  M. Pareschi,et al.  A Numerical Simulation of the Plinian Fall Phase of 79 A.D. Eruption of Vesuvius , 1988 .

[8]  Costanza Bonadonna,et al.  Total grain-size distribution and volume of tephra-fall deposits , 2005 .

[9]  A. Saltelli,et al.  Importance measures in global sensitivity analysis of nonlinear models , 1996 .

[10]  D. Pyle.  The thickness, volume and grainsize of tephra fall deposits , 1989 .

[11]  Giancarlo Neri,et al.  Satellite analysis and PUFF simulation of the eruptive cloud generated by the Mount Etna paroxysm of 22 July 1998 , 2002 .

[12]  Andrew W. Woods,et al.  The fluid dynamics and thermodynamics of eruption columns , 1988 .

[13]  Ilya M. Sobol,et al.  Sensitivity Estimates for Nonlinear Mathematical Models , 1993 .

[14]  Stephen Self,et al.  GOES weather satellite observations and measurements of the May 18, 1980, Mount St. Helens eruption , 1995 .

[15]  G. Macedonio,et al.  A model for the numerical simulation of tephra fall deposits , 2005 .

[16]  R. Sparks,et al.  Quantitative models of the fallout and dispersal of tephra from volcanic eruption columns , 1986 .

[17]  Stefano Tarantola,et al.  Uncertainty and sensitivity analysis: tools for GIS-based model implementation , 2001, Int. J. Geogr. Inf. Sci..

[18]  M. T. Pareschi,et al.  A numerical model for simulation of tephra transport and deposition: Applications to May 18, 1980, Mount St. Helens eruption , 1988 .

[19]  Roberto Santacroce,et al.  Assessing pyroclastic fall hazard through field data and numerical simulations: Example from Vesuvius , 2003 .

[20]  Alfred J Prata,et al.  Retrieval of microphysical and morphological properties of volcanic ash plumes from satellite data: Application to Mt Ruapehu, New Zealand , 2001 .

[21]  R. S. J. Sparks,et al.  A gravity current model for the May 18, 1980 Mount St Helens plume , 1980 .

[22]  Augusto Neri,et al.  The VOL-CALPUFF model for atmospheric ash dispersal: 1. Approach and physical formulation , 2008 .

[23]  A. Woods,et al.  Wind-driven dispersal of volcanic ash plumes and its control on the thermal structure of the plume-top , 1995 .

[24]  I. Sobol.  On the distribution of points in a cube and the approximate evaluation of integrals , 1967 .

[25]  Jon C. Helton,et al.  Uncertainty and sensitivity analysis techniques for use in performance assessment for radioactive waste disposal , 1993 .

[26]  V. Neall,et al.  Environmental hazards of fluoride in volcanic ash: a case study from Ruapehu volcano, New Zealand , 2003 .

[27]  Haraldur Sigurdsson,et al.  Influence of particle aggregation on deposition of distal tephra from the MAy 18, 1980, eruption of Mount St. Helens volcano , 1982 .

[28]  M. Jansen,et al.  Monte Carlo estimation of uncertainty contributions from several independent multivariate sources. , 1994 .

[29]  Richard Turner,et al.  Performance of the program ASHFALL for forecasting ashfall during the 1995 and 1996 eruptions of Ruapehu volcano , 1999 .

[30]  K. Dean,et al.  PUFF: A high-resolution volcanic ash tracking model , 1998 .

[31]  T. Koyaguchi,et al.  Reconstruction of eruption column dynamics on the basis of grain size of tephra fall deposits: 1. Methods , 2001 .

[32]  Costanza Bonadonna,et al.  Sedimentation from strong volcanic plumes , 2003 .

[33]  Geoffrey Ingram Taylor,et al.  Turbulent gravitational convection from maintained and instantaneous sources , 1956, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[34]  Lionel Wilson,et al.  Explosive volcanic eruptions — V. Observations of plume dynamics during the 1979 Soufrière eruption, St Vincent , 1982 .

[35]  Marcus I. Bursik,et al.  Effect of wind on the rise height of volcanic plumes , 2001 .

[36]  R. Sparks,et al.  Fall-out and deposition of volcanic ash during the 1979 explosive eruption of the soufriere of St. Vincent , 1982 .

[37]  L. Wilson,et al.  Explosive volcanic eruptions - VI. Ejecta dispersal in plinian eruptions: the control of eruption conditions and atmospheric properties , 1987 .

[38]  Costanza Bonadonna,et al.  Modeling tephra sedimentation from a Ruapehu weak plume eruption , 2005 .

[39]  M. Nathenson,et al.  Another look at the calculation of fallout tephra volumes , 1992 .

[40]  S. F.L,et al.  Mantle-lower crust petrology from inclusions in basaltic rocks in Eastern Australia — an outline , 1982 .

[41]  Charles B. Connor,et al.  ESTIMATION OF VOLCANIC HAZARDS FROM TEPHRA FALLOUT , 2001 .

[42]  Simona Scollo,et al.  Tephra fallout of 2001 Etna flank eruption: Analysis of the deposit and plume dispersion , 2007 .

[43]  Marcus I. Bursik,et al.  Sedimentation of tephra by volcanic plumes: I. Theory and its comparison with a study of the Fogo A plinian deposit, Sao Miguel (Azores) , 1992 .

[44]  C. Connor,et al.  Inversion Is the Key to Dispersion: Understanding Eruption Dynamics by Inverting Tephra Fallout , 2006 .

[45]  A. Saltelli,et al.  Making best use of model evaluations to compute sensitivity indices , 2002 .

[46]  Andrew W. Woods,et al.  Explosive Volcanic Eruptions , 2001 .

[47]  P. Froggatt.  Review of methods of estimating rhyolitic tephra volumes; applications to the Taupo volcanic zone, New Zealand , 1982 .

[48]  R. S. J. Sparks,et al.  Thickness variations and volume estimates of tephra fall deposits: the importance of particle Reynolds number , 1998 .

[49]  G. Walker.  Explosive volcanic eruptions — a new classification scheme , 1973 .

[50]  Saltelli Andrea,et al.  Global Sensitivity Analysis: The Primer , 2008 .

[51]  T. Koyaguchi,et al.  Reconstruction of eruption column dynamics on the basis of grain size of tephra fall deposits: 2. Application to the Pinatubo 1991 eruption , 2001 .

[52]  Augusto Neri,et al.  The VOL‐CALPUFF model for atmospheric ash dispersal: 2. Application to the weak Mount Etna plume of July 2001 , 2008 .

[53]  Arlene Laing,et al.  Probabilistic modeling of tephra dispersal: Hazard assessment of a multiphase rhyolitic eruption at Tarawera, New Zealand , 2005 .