Testing the accuracy of a 1‐D volcanic plume model in estimating mass eruption rate

Abstract

During volcanic eruptions, empirical relationships are used to estimate mass eruption rate from plume height. Although simple, such relationships can be inaccurate and can underestimate rates in windy conditions. One-dimensional plume models can incorporate atmospheric conditions and give potentially more accurate estimates. Here I present a 1-D model for plumes in crosswind and simulate 25 historical eruptions where plume height H obs was well observed and mass eruption rate M obs could be calculated from mapped deposit mass and observed duration. The simulations considered wind, temperature, and phase changes of water. Atmospheric conditions were obtained from the National Center for Atmospheric Research Reanalysis 2.5°model. Simulations calculate the minimum, maximum, and average values (M min , M max , and M avg ) that fit the plume height. Eruption rates were also estimated from the empirical formula M empir = 140H obs 4.14 (M empir is in kilogram per second, H obs is in kilometer). For these eruptions, the standard error of the residual in log space is about 0.53 for M avg and 0.50 for M empir . Thus, for this data set, the model is slightly less accurate at predicting M obs than the empirical curve.The inability of this model to improve eruption rate estimates may lie in the limited accuracy of even well-observed plume heights, inaccurate model formulation, or the fact that most eruptions examined were not highly influenced by wind. For the low, wind-blown plume of 14-18 April 2010 at Eyjafjallajökull, where an accurate plume height time series is available, modeled rates do agree better with M obs than M empir .

Uncertainties in volcanic plume modeling: A parametric study using FPLUME

“…As expected, plume bending increases with wind, resulting on a decrease of plume height (see e.g. Bursik, 2001;Folch et al, 2012;Devenish, 2013;Woodhouse et al, 2013;Mastin, 2014). Because of the stronger intensity characterizing the reference wind profile, the effect is more pronounced for the weak plumes, with differences of up to 80% between windless and reference windy conditions.…”

Laboratory experiments of forced plumes in a density‐stratified crossflow and implications for volcanic plumes

“…The maximum height reached by a volcanic column is a key parameter to assess in near real time the mass discharge rate feeding an eruption [e.g., Mastin et al , ], which is used in turn to forecast the concentration of ash injected into the atmosphere [e.g., Kaminski et al , ]. Low‐altitude winds are known to affect the plume dynamics and reduce its maximum height for a given eruption flow rate by more vigorous entrainment [ Bursik , ; Degruyter and Bonadonna , ; Woodhouse et al , ; Suzuki and Koyaguchi , ; Mastin , ]. Understanding quantitatively the influence of atmospheric winds on a volcanic column is therefore crucial to improve the assessment of volcanic hazards related to explosive eruptions [ Houghton et al , ].…”

TephraProb: a Matlab package for probabilistic hazard assessments of tephra fallout

“…This version of TephraProb is published on GitHub as a basis for further development based on inputs from the scientific community. Identified directios of development include i) the implementation of a variety of models available in the literature to quantify ESPs such as Sparks (1986); Wilson and Walker (1987); Mastin et al (2009);Woodhouse et al (2013) and Mastin (2014), ii) probabilistic inversion schemes to systematically assess the likelihood of past events (Elissondo et al 2016) and iii) better integration of Reanalysis datasets to calculate the required atmospheric parameters (Degruyter and Bonadonna 2012).…”