IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O1

Room A1

Date/Time: July 24 8:45-9:00

Inversion of field data for reconstructing plume dynamics of past eruptions: state of theart and perspectives
Roberto Sulpizio
Dipartimento di Scienze della Terra e Geoambientali-UNIBA, Bari, Italy
E-mail: roberto.sulpizio@uniba.it

Eruptive columns commonly comprise three distinct regions characterised by different flow regimes: a lower basal
gas-thrust or jet region, an intermediate convective region, and an upper umbrella region. Typically, the gas-thrust
region extends only up to a small fraction of the total column height and it is characterised by a steep decreaseof the gas particle mixture velocity due to loss of momentum. In contrast, the convective region is dominated bybuoyancy forces acting on the hot erupted gases and heated entrained air. Finally, above the neutral buoyancy
level, the erupted material spreads under the effect of winds and atmospheric turbulence to form the umbrella
region. Sizes of erupted particles may vary by several orders of magnitude, ranging from very fine sub-micron ash
to clasts larger than one meter in diameter. The largest and heaviest particles leave the column at lower levels
and follow complicated ballistic and non-ballistic trajectories, whereas the finest particles may remain entrapped bygeostrophic winds for several years affecting the global climate. Particles within the intermediate to fine size range
are advected by wind, diffused by turbulence, settled by gravity and deposited finally on the ground at medium
to distal distances. Therefore, the physics of volcanic plumes depends by different several factors, which can besummarised as total mass and its distribution (total grain size), initial momentum, available heat, efficiency of air
entrainment and interaction with the atmospheric wind field. The definition of these parameters is essential forhaving models able to predict ground ash loading and atmospheric ash concentrations, which are of fundamental
importance for public safety in volcanic areas. However, The characterisation of these parameters is hard to obtainfrom direct observation of eruption plumes, and are even more challenging to gain from inversion of data frompyroclastic deposits.
Here, a critical overview about models (field, experimental and numerical) for inversion of field data to gain insights
on the physics of volcanic plumes is proposed. A special focus is devoted to some physical parameters that are far
from a satisfactory inversion (e.g. reconstruction of total grain size distribution), and clues for future research aresuggested.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

862

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O2

Room A1

Date/Time: July 24 9:00-9:15

Unsteady turbulent jet dynamics with implications for volcanic plumes
Kirsten N. Chojnicki1 , Amanda B. Clarke2 , Ronald J. Adrian2 , Jeremy C. Phillips3
1

Scripps Institute of Oceanography, U.S.A., 2 Arizona State University, U.S.A., 3 Bristol University, U.K.
E-mail: kchojnicki@ucsd.edu

To investigate the response of volcanic plumes to unsteady vent conditions, an analogue study of laboratory jets
was conducted. Lab jets were driven with injection rates that varied over time in a Gaussian-like history. Resultant
jet heights showed a logarithmic dependence on time; this trend is in contrast to the power law dependence ontime expected for jet heights from steady-state or instantaneous injection rates. The logarithmic time dependence
may reflect the dominance of coherent vortices that were detected in the unsteady jet interiors. These vortices
are large and extend from beyond the visible boundary of the jet through the jet interior. They are also persistent
with lifetimes that are comparable to the jet rise time. The large and long-lived coherent vortices may not transport
mass, momentum and energy in a way that is reasonably described by homogeneous turbulence concepts that
underlie steady-state and instantaneous models of volcanic plumes and jets. Consequently, this work implies that
it is first necessary to understand transport by large and long-lived coherent vortices before that process can beparameterized for use in models of unsteady turbulent jets. Despite this need for a complex transport description,
the behavior of the flow front can be described with a simple expression that consolidates the jet rise behavior froma range of experimental conditions to a single trend. This expression is non-dimensional using a length and timescale derived from a linear fit of jet height and the logarithm of time. Data from a single volcanic plume observation(Mori and Burton, 2009, JVGR, 188, p. 395-400) also follows the same trend as that discovered in the laboratory.
This synthesis lends a tenuous confidence to the relevance of the experimental model to the natural system.
Successful comparison with a larger natural data set may better delimit the model applicability but such data isabsent from the literature. Nevertheless, the logarithmic time dependence contrasts the power law dependence
commonly employed to interpret volcanic plume observations, and suggests that this new experimental model may
be more appropriate for interpreting short-lived volcanic events.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

863

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O3

Room A1

Date/Time: July 24 9:15-9:30

Buoyancy of plume-sourced ash clouds: implications for ash transport modelling.
Stephen RJ Sparks1 , Peter Baines2 , Rose Burden1 , Samantha Engwell1 , Andrew Hogg3 , Herbert E
Huppert1 , Chris Johnson3 , Jessica Kandlbauer1 , Jeremy C Phillips1 , Mark Woodhouse3
1

School of Earth Sciences, Bristol University, United Kingdom, 2 Department of Infrastructure
Engineering, University of Melbourne, Australia, 3 School of Mathematics, Bristol University, United
KingdomE-mail: Steve.Sparks@bristol.ac.uk

Volcanic plumes ascend high into the atmosphere where they spread out at a level of neutral buoyancy to form
intrusions. The structure of these intrusions depends on the relative strength of the intrusions, the ambient wind
and the local atmospheric stratification. In a strong wind, moderate to weak sized eruptions form bent over plumes
while in more powerful eruptions or in eruptions with a weak wind, they typically form umbrella clouds, which spreadin all directions. Irrespective of the wind the plumes reach dynamical equilibrium with the wind field further from thevolcanic source. The motion of such plume-fed intrusions is governed by buoyancy. The spreading of intrusions iscontrolled by the volumetric flux of the feeding plume at the height of neutral buoyancy and the density stratificationin the atmosphere, but not by the density of the intrusion itself. For the case of a symmetrically spreading umbrella
cloud the thickness decreases with distance. Although more complex in detail, intrusions affected by the wind also
thin quite rapidly with distance. Buoyancy thinning can explain why ash clouds are observed to become very thinquite close to source. Advection diffusion models are now widely used to forecast ash clouds dispersal and ash
deposition. Such models typically assume ash is dispersed vertically above the source and assume ash particles
act as heavy (sedimenting) tracers that are spread by atmospheric diffusion. Buoyancy effects are ignored. We
contend that such models are not a correct description of the physics of ash clouds in regions where buoyancy
effects are significant. For very powerful eruptions buoyancy effects are dominant to distances of hundreds ofkilometres or more; it seems unlikely that an advection-diffusion model could reproduce observed ash distributions
since such models cannot have upwind or very extensive cross-wind spreading. For weaker plumes that aremarkedly affected by wind, advection-diffusion models are useful mathematical descriptions that can be calibrated
to give good forecasts of ash transport. However, this does not mean they are good physical models of the process.
Models of buoyancy spreading suggest that it can be the main cause of lateral spreading of wind blown clouds tosignificant distances (perhaps tens or hundreds of kilometres). Operational models of ash dispersal are likely toremain structured as advection diffusion models, so they may need some empirical adjustments to take accountof buoyancy. For example it might be better to have source terms, which assume ash is concentrated in narrow
height intervals above the source (at one or more discrete levels rather than distributed vertically). It seems unwise
to continue using such models for very powerful eruptions.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

864

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O4

Room A1

Date/Time: July 24 9:30-9:45

Quantifying the uncertainty in estimation of the volcanic source mass flux from observed
plume dynamics
Jeremy C Phillips1 , Mark J Woodhouse2 , Andrew J Hogg2 , Jonathan C Rougier2 , Liam J Dowson1 ,Halldor Bjornsson3
1

School of Earth Sciences, University of Bristol, United Kingdom, 2 School of Mathematics, University ofBristol, United Kingdom, 3 Icelandic Meteorological Office, Reykjavik, IcelandE-mail: j.c.phillips@bristol.ac.uk

Estimates of volcanic source mass flux, currently deduced from observations of eruption plume height, are crucial
for ash dispersion models for aviation and population hazard. Recent modelling studies have shown that the effectof the atmospheric wind on a volcanic plume can significantly reduce its height compared with the case of no wind,and so source mass flux can be underestimated by up to two orders of magnitude (Degruyter and Bonadonna,
2012; Woodhouse et al., 2012). Volcanic and atmospheric input parameters have associated measurement
uncertainty, and the models incorporate epistemic uncertainty due to their formulation. In this study we quantify
the magnitude of these uncertainties in order to identify which input parameters introduce the greatest uncertainty
into estimates of volcanic source mass flux, and to identify where improvements in measurement capability would
provide the greatest improvement to mass flux estimates.

The integral model of Woodhouse et al (2012) is used as a candidate model for uncertainty quantification,and it is formulated as a set of four coupled differential equations to express conservation principles for mass,
momentum and enthalpy, and algebraic relationships for entrainment of atmospheric air, plume density andvariation of atmospheric properties with height. Input parameters from the volcanic source include the ash massflux, initial velocity, vent radius and ash temperature, and atmospheric properties can be taken from radiosonde,
NWP or ECMWF reanalysis sources. The model can be rapidly solved numerically, so Monte Carlo methods
have been used to explore the effect of parameter uncertainty. The greatest uncertainty in the source mass flux
arises from the estimation of source temperature, with much weaker dependence on solid mass fraction in theinitial plume. Woodhouse et al (2012) also identified a dimensional relationship between plume height, wind shear
and source mass flux, which was fitted to their numerical model output. We also explore the uncertainty in thisrelationship, as a form of simplified model emulator, finding that variability in the wind shear has a much stronger
affect that the other properties of the atmosphere.

Integral models of wind-affected volcanic plumes can also be fitted to observations of plume trajectory toprovide tools to rapidly estimate the source mass flux. We use webcam imagery of the 2010 Eyjafjallajokull
eruption to explore how the uncertainty in meteorological data compares with uncertainty in the parameters thatare used to estimate the volcanic source mass flux. From this we are able to identify the parameters whose values
have the greatest influence on the uncertainty in volcanic source term estimation.

References: Degruyter, W. and Bonadonna, C. (2012) Geophys.

Res.

Woodhouse, M.J. et al (2012) J. Geophys. Res. doi:10.1029/2012JB009592©IAVCEI 2013 Scientific Assembly. All rights reserved.

865

Letts.

doi:10.1029/2012GL052566;

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O5

Room A1

Date/Time: July 24 9:45-10:00

Integral models of volcanic plumes in a cross wind.
Mark J Woodhouse1 , Andrew J Hogg1 , Jeremy C Phillips2 , Steve Sparks2
1

School of Mathematics, University of Bristol, UK, 2 School of Earth Sciences, University of Bristol, UK
E-mail: mark.woodhouse@bristol.ac.uk

Explosive volcanic eruptions can inject large quantities of ash into the atmosphere which can be transported overlarge areas. The recent eruptions of Eyjafjallajökull 2010, Grimsvötn 2011 and Cordón-Caulle 2011 demonstrate
the fragility of international transport infrastructure to relatively small volcanic eruptions. Managing airspace during
volcanic crises by forecasting atmospheric ash dispersion requires, as an input, estimates of the source conditions
at the volcanic vent. The source conditions are currently difficult to measure directly during an eruption.

Integral models of volcanic plumes can be used to estimate the source conditions during eruptions by comparing
model predictions with observations. The simple mathematical structure of integral models allows solutions to
be readily obtained, allowing an assessment of source and atmospheric controls to be made. We formulate an
integral model of volcanic eruption columns that utilizes meteorological observations to determine the trajectory of
the plume motion. We demonstrate, for weakly-explosive eruptions, atmospheric conditions have a strong effecton the rise of the plume. In particular, atmospheric winds strongly influence the rise of volcanic plumes, with thewind restricting the rise height such that obtaining equivalent rise heights for a plume in a windy environment would
require an order of magnitude increase in the source mass flux over a plume in a quiescent environment.

The mixing of atmospheric air with the magmatic gases and pyroclasts plays a crucial role in the dynamics
of the ascent of the plume. The entrainment process is typically parameterized in integral models using simple,
phenomenological closures based on the classical entrainment assumption of Morton, Taylor & Turner (1957).
Here we discuss the parameterization of entrainment, investigate the effect of wind enhanced entrainment on
plume dynamics, and assess the sensitivity of integral model results to the entrainment coefficients employed.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

866

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O6

Room A1

Date/Time: July 24 10:00-10:15

Impact of wind on the condition for column collapse of volcanic plumes
Wim Degruyter1 , Costanza Bonadonna2
1

Georgia Institute of Technology, USA, 2 University of Geneva, Switzerland
E-mail: wim.degruyter@eas.gatech.edu

Collapse of volcanic plumes has significant implications for eruption dynamics and associated hazards. We show
how eruptive columns can collapse and generate pyroclastic density currents (PDCs) as a result of not only thesource conditions, but also of the atmospheric environment. The ratio of the potential energy and the kinetic
energy at the source quantified by the Richardson number, and the entrainment efficiency quantified by the radial
entrainment coefficient have already been identified as key parameters in controlling the transition between abuoyant and collapsing plume. Here we quantify how this transition is affected by wind using scaling arguments incombination with a one-dimensional plume model. Air entrainment due to wind causes a volcanic plume to lower its
density at a faster rate and therefore to favor buoyancy. We identify the conditions when wind entrainment becomesdominant over radial entrainment and quantify the effect of wind on column collapse. We propose a generalized
regime diagram based upon (i) the ratio of the Richardson number and the radial entrainment coefficient and (ii) the
ratio of the wind entrainment rate and the radial entrainment rate. Previously used diagrams under the conditionof choked flow can be considered as a special case within this diagram. The mass flow rate is shown to be an
ambiguous parameter to assess column collapse as both an increase and decrease can lead to collapse. Rather
the effects of its independent constituents (density, exit velocity, and vent radius) should be considered.

Wind significantly affects eruption dynamics as it can (i) reduce the final height of the plume, (ii) be thedominant entrainment mechanism, and (iii) prevent a plume from collapsing. Therefore, strong winds are natural
allies in reducing hazards present at volcanoes both on a proximal (less PDCs) and regional scale (reducedheight). Observations of several eruptions qualitatively confirm this behavior. In particular, the parameter range
derived for the 2010 Eyjafjallajokull eruption suggests the wind enhanced the buoyancy of the plume, where in astill environment this plume would have probably collapsed.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

867

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A1_3E-O7

Room A1

Date/Time: July 24 10:15-10:30

A fast Eulerian multiphase flow model for the three-dimensional numerical simulation of
non-equilibrium effects in turbulent volcanic plumes
Matteo Cerminara1 , Tomaso Esposti Ongaro2 , Maria Vittoria Salvetti3 , Luigi Carlo Berselli3
1

Scuola Normale Superiore, Italy, 2 Istituto Nazionale di Geofisica e Vulcanologia, Italy, 3 Universita’ diPisa, Italy
E-mail: matteo.cerminara@sns.it

We have developed a fast Eulerian model for the Large Eddy Simulation (LES) of turbulent volcanic plumes. The
model is based on the equilibrium-Eulerian approximation (Ferry and Balachandar, Int. J. Multiph. Flow 2001;
Cantero et al., J. Geophys. Res., 2008) for a polydisperse flow.
This approach gives particular attention to the particle grain size distribution and its interaction with the turbulence.
We are indeed particularly interested in the disequilibrium between the ash and the gaseous part of the volcanic
mixture, our aim being to properly simulate phenomena like preferential concentration and plume entrainment.
In the limit of fine particles (at Stokes number < 0.2) and dilute regimes (particle volume concentration < 1.e-3), suchmethod allows to overcome the limitations of the pseudogas models (assuming a perfect kinematic and thermal
equilibrium between gas and particles - Oberhuber et al, J. Volcanol. Geoth. Res., 1998; Suzuki et al., J. Geophys.
Res., 2005) without entailing the complexity and computational cost of the fully coupled multiphase flow Eulerianmodels (Neri et al., J. Geophys. Res., 2003; Dufek and Bergantz, Theor. Comput. Fluid Dyn., 2007).
To model the non-linear coupling between turbulent scales and the effect of sub-grid turbulence on the large-scale
dynamics, we have adopted the LES formalism (which is preferable in transient regimes) for compressible flows.
Our computational work is based on development and exploitation of these models into the numerical solvers of
OpenFOAM, which is one of the best known CFD open source parallel software packages.
Preliminary numerical benchmarks demonstrate that the model is able to capture important non-equilibrium
phenomena in gas-particle mixtures, such as particle clustering and ejection from large-eddy turbulent structures,
as well as compressibility and thermal effects.
A quantitative assessment of the reliability of Direct Numerical Simulation (DNS) and LES results with respect tomodeling approximations and numerical errors has been carried out by comparing numerical results to experimental
and computational studies of homogeneous, isotropic turbulence.
In such a simplified geometry, the numerical solver is able to accurately reproduce the turbulent spectrum and theKolmogorov energy cascade.
Preliminary three-dimensional numerical simulation of volcanic plume dynamics demonstrate that gas-particle
non-equilibrium phenomena have a significant impact on turbulent structures and can affect the entrainment rate
and the atmospheric dispersal of volcanic ash.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

868

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O8

Room A1

Date/Time: July 24 10:45-11:00

Do Prince Ruperts Drops provide insight into phreatomagmatic fragmentation?
Katharine V Cashman, Alison C Rust, Emma J Nicholson
University of Bristol, UK
E-mail: glkvc@bristol.ac.uk

Prince Ruperts Drops (PRDs) are tadpole-shaped glass beads that are known for their unusual fracture properties:
the head of the bead is very strong, but the entire bead will shatter explosively if the tail is broken. These
properties result from residual stresses within the glass beads. Compressive stresses on the outer margin of the
PRDs provide the strength. Tensile stresses inside the beads drive explosive fracture propagation when the outer
compression zone is damaged. Fractures propagate at a rate determined by the terminal crack speed for the glass.
Key to the residual stress geometry is the process by which PRDs are made, which involves dripping molten glass
into water.

Water-quenching of silicate melts also occurs when rising magma encounters shallow water bodies in subglacial,submarine and sublacustrine environments. Such eruptions are known to generate more energetic eruptions, andfiner particle sizes, than eruptions that do not involve an external water source. Most studies of explosive melt-waterinteraction are based on concepts of molten fuel-coolant interaction (MFCI), with experimental studies designed to
study mechanisms of melt-water mixing. From this perspective, the energy release is determined by the efficiencyof heat transfer and resulting volume expansion generated by the transformation of water to steam. Generationof fine ash particles is assumed to require brittle fragmentation, with the resulting grain size attributed to (1) thepore geometry, (2) a single episode of quench granulation, or (3) turbulent shedding of successive quenched layers.

To date, no examination of hydromagmatic volcanism has considered the role of residual stress on the
fragmentation process. However, residual stress is common in air-quenched basaltic glass, as evidenced by the
spontaneous ejection of glass flakes from pahoehoe flow surfaces. The blocky form of many hydromagmatic
pyroclasts also suggests that fragmentation occurs in the brittle regime, although particles with the more fluidal
shapes of Peles hair and Peles tears (i.e., tadpole-shaped glass beads) are not uncommon in phreatomagmatic
deposits. Evidence of thermal contraction is also common as cracked outer surfaces of water-generated ash
particles, as partially disaggregated surface skins on Peles tears, and as striations on the surface of blocky
particles. Fragments generated by explosive disruption of PRDs show similar blocky to plately forms and surface
striations. On the basis of these similarities, we suggest that residual stresses such as those that control explosivefragmentation of PRDs may contribute to fine ash production in hydrovolcanic eruptions. Spontaneous disruptionof rapidly quenched glass provides a mechanism for the proposed model of fragmentation by turbulent shedding
and suggests that studies of crack propagation in glasses and glass ceramics may contribute to our understandingof fragmentation processes.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

869

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O9

Room A1

Date/Time: July 24 11:00-11:15

A new model for the predication of drag of non-spherical volcanic particles
Gholamhossein Bagheri1 , Costanza Bonadonna1 , Irene Manzella1 , Piero Pontelandolfo2 , Patrick Haas2
1

Section of Earth and Environmental Sciences, University of Geneva, Switzerland, 2 University ofApplied Sciences Western Switzerland in Geneva (HES-SO/hepia), Switzerland
E-mail: Gholamhossein.bagheri@unige.ch

Estimation of drag of non-spherical particles is the most important parameter in many multi-phase flow processes
in both industry and nature. Although many experimental results on the drag of non-spherical particles exist in theliterature, only a few of them are based on measurements in air. We present a new model for the prediction of thedrag of non-spherical solid particles of regular and irregular shape that travel in air. Reynolds numbers investigatedare between 10 and 105 (i.e. laminar to turbulent regimes). The results are obtained from experiments performedon micron size particles in a falling column and on millimetric size particles suspended in a vertical wind tunnel.
Both apparatus were designed and built at University of Geneva for the study of sedimentation and aggregationof volcanic particles. Particle shape factors are measured based on various methods existing in the literature andbenchmarked against our experimental results. Shape factors are calculated with different instruments dependingon the size of particles such as 3D-scanning and image analysis. New easy to measure shape factors are
introduced which have the highest correlation with the measured drag coefficient of particles. Performance ofthe models is benchmarked against well-known spherical and non-spherical models. As an example, we havefound that both existing spherical and non-spherical models can estimate settling velocity of volcanic particles withan average error of about 30%. We have also found that the effect of surface roughness on terminal velocity
of non-spherical particles of millimetric size is almost negligible. Finally, we observed that secondary motions ofparticles are considerably higher at high Reynolds numbers. This implies that particles falling in the turbulent regime
are better characterized by a range of terminal velocities instead of a single value especially in case of particles
with high variation in their projected area. Our experimental benchmarks show that our new model is a reliable andeasy to apply model for estimating drag coefficient of non-spherical particles of various shapes in a wide range of
Reynolds number.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

870

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O10

Room A1

Date/Time: July 24 11:15-11:30

Determination and evolution of source parameters in volcanic eruptions; the
FUTUREVOLC supersite approach
Magnus T Gudmundsson1 , Halldor Bjornsson2 , Maurizio Ripepe3 , Frank S Marzano4 , Bo Galle5 , Bernd
Zimanowski6 , Arve Killing7 , Thomas R Walter8 , Costanza Bonadonna9 , Jeremy Phillips10 , Alessandro
Aiuppa11 , Fred Prata12 , Errico Picciotti13 , Emanuele Marchetti14 , Olgeir Sigmarsson15
1

Nordvulk, Institute of Earth Sciences, University of Iceland, Iceland, 2 Icelandic Meteorological Office,Iceland, 3 University of Florence, Italy, 4 CETEMPS, University L’Aquila, Italy, 5 Chalmers University,
Sweden, 6 Universty of Wuerzburg, Germany, 7 NILU-Norwegian Institute for Air Research, Norway,
8
GFZ, Germany, 9 University of Geneva, Switzerland, 10 University of Bristol, UK, 11 University of Palermo,
Italy, 12 Nicarnica, Norway, 13 HIMET, Italy, 14 iTEM, Italy, 15 University Blaise Pascal, France
E-mail: mtg@hi.is

Recent explosive eruptions in Iceland and South America have highlighted the need for reliable near real time
estimates of eruption rates. At present the method most frequently used for all but the smallest events, is applying
the theoretically and empirically derived relations between eruption plume height and mass eruption rate; often
using weather radar data to derive plume heights. In recent years several new methods have been developed thatprovide independent estimates of volumetric flow rate, plume particle concentrations, exit velocities, electric field
generation, gas fluxes, lightning intensity in eruption clouds as well as satellite based methods for plume tracking
and atmospheric mass loading. Each method has its strengths and drawbacks. By combining measurementsof the all the above parameters into a single system, a much more reliable estimate of eruption rate should beobtained. The compilation of such a system is one of the aims of FUTUREVOLC, a European collaborative
project funded through the EU FP7 Environment call encompassing 26 partners in 10 European countries. The
main objectives of FUTUREVOLC are to establish an integrated volcanological monitoring procedure, develop
new methods to evaluate volcanic crises, increase scientific understanding of magmatic processes and improvedelivery of relevant information to civil protection and authorities. FUTUREVOLC is a supersite project, where
Iceland has been selected as the target area. In its comprehensive approach to the study of volcanic phenomena,
subsurface magma tracking is combined with physical volcanology and atmospheric science. The integrated systemfor estimation of eruption source parameters will be composed of arrays of sensors that are already in place will be
set up in the summer of 2013. The components of the monitoring system include continuously recording real time
devices: two C-band weather radars, two mobile X-band radars, radiosondes for ambient atmosphere monitoring,
infrasound arrays, arrays of time lapse cameras, electric field sensors, automated tephra samplers and analysers,
gas monitoring systems and lightning detection systems. The signals from these systems will be supplemented byaircraft observations and the deployment of a mobile field lab for rapid characterization of tephra. The data from allthese sources will be fed into an integrated near real-time system that will evaluate the eruption rate. New algorithms
for analysis of radar backscatter and both physics-based and empirical plume models will be implemented as a partof the system. Various data from previous eruptions, including ground truth information, will be used to calibrate
the system, which is expected to be operational in 2016.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

871

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O11

Room A1

Date/Time: July 24 11:30-11:45

Full bandwidth remote sensing for total parameterization of volcanic plumes
Sebastien Valade1 , Andrew Harris1 , Georgina Sawyer1 , Franck Donnadieu1 , Philippe Labazuy1 , Karim
Kelfoun1 , Maxime Bombrun2 , Vincent Barra2 , Claude Hervier3 , Maurizio Ripepe4 , Dario Delle Donne4 ,Giorgio Lacanna4 , Mike Burton5 , Laure Chevalier1 , Thomas Stachowicz1
1

LMV, Universite Blaise Pascal, 63000 Clermont-Ferrand, France, 2 LIMOS, Universite Blaise Pascal,
63117 Aubiere, France, 3 OPGC, Universite Blaise Pascal, 63117 Aubiere, France, 4 Universita diFirenze, Dipartimento di Scienze della Terra, 50121 Firenze, Italy, 5 INGV, Via della Faggiola 32, 56126
Pisa, Italy
E-mail: s.valade@opgc.univ-bpclermont.fr

If we are to adequately track the emission, ascent and dispersion of a volcanic plume, we first need to measure
a number of source condition parameters. These include mass flux, exit velocity, particle size distribution, andplume density or ash concentration. Because of the difficulty of close approach to an active volcanic vent, suchmeasurements need to be remote. Moreover, these need to span a broad range of the electromagnetic spectrum
in order to fully parameterize the volcanic plume. With this in mind, we designed in 2012 an experiment involving
the full range of modern ground-based remote sensing capabilities, from microwave to ultraviolet wavelengths.
Stromboli (Italy) was selected for this test deployment, both for its ease of access and reliability as particle emitter.
Our aim was to: characterize explosive eruption dynamics at the highest possible spatio-temporal resolution, test
the combined deployment of a complete instrument package, and evaluate its potential for operational plumetracking with a special emphasis on extracting source condition parameters. The equipment package deployed
involved the following instruments, beginning with the longest wavelength: (i) 1 Doppler radar (VOLDORAD2,
23.5 cm wavelength) sampling at 10 Hz, used to quantify the ejection velocities and mass fluxes, (ii) 2 thermal
infrared cameras (FLIR Systems, 8-14 micrometers) sampling at 200 Hz and 30 Hz, used to track the near-ventemission and the plume ascent and dispersion, (iii) 1 very high frame rate camera (Photron Fastcam SA3, visible
and near-infrared) sampling up to 2000 Hz, used to characterize the highest velocities for particles carried by
the gas phase, (iv) 2 stereoscopic cameras (IP Basler, visible and near infrared) sampling at 25 Hz, used toreconstruct 3-D particle trajectories and further constrain their sizes, (v) 1 SO2 camera (310 and 330 nm) and 1
OP-FTIR, used to quantify the mass of gas. In addition, a permanent seismic and infrasonic array was used tocharacterise the seismic and acoustic signal associated with explosive activity, and in-situ sampling of particles
landing in well-defined areas was done to carry geochemical, density, vesicle, and crystal analysis of the ejecta.
The ongoing work involves creating code to process and integrate all data sets so as to output the source terms ina rapid-to-real-time frame. We here give special emphasis on the mutual feedback between infrared cameras andDoppler radar, where the first provide particle size distribution to the second to constrain the mass flux.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

872

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O12

Room A1

Date/Time: July 24 11:45-12:00

Eruptions on the fast track, part b): The variability of strombolian explosions from highspeed thermal and optical videos
Damien Gaudin1 , Jacopo Taddeucci1 , Piergiorgio Scarlato1 , Monica Moroni2
1

Department of Seismology and Tectonophysics, HP-HT Lab, INGV Roma, Italy, 2 DICEA , Sapienza
UniversitÃă di Roma, Rome, Italy
E-mail: damien.gaudin@ingv.it

Strombolian activity style is characterised by discrete explosions at variable frequency, lasting a few to tens ofseconds, and ejecting pyroclasts at heights of tens to hundreds of meters. New imaging techniques, including
high speed camera observations, have already shown that these explosions are complex phenomena that include
pyroclast ejection pulses, typically lasting tenths of seconds, characterized by a non-linear decay on the ejection
velocity over time and related to individual pressure release events. Here, we show the results of a new computing
techniques (described in a companion abstract, Eruptions on Fast Track, part a), based on joint applicationof Particle Image Velocimetry (PIV, providing information on the ash and gas clouds) and Particle Tracking
Velocimetry (PTV, providing information on the cm-to m-sized pyroclasts) to high-speed visible and thermal videosof Strombolian explosions at Stromboli (Italy) and Yasur (Vanuatu) volcanoes. In comparison to previous studies,
which manually analysed the videos, the techniques we use increase by ten-fold the number of identified andmeasured particles, allowing a significant advancement in the study of Strombolian dynamics.
A variable number (a few to several tens) of well-defined ejection pulses are present in all analyzed explosions.
Pulses sometimes are organised in larger ejection events, or super-pulses, lasting up to a few seconds,
characterised by a velocity decay following the same non-linear trend shown by pulses. The mean source depth ofthe pulses, modeled from the velocity decay trends, are mostly in the tens of meters range and remains constanton the whole explosion, while super-pulses seems to originate deeper (up to hundred of meters) in the conduit.
Within each pulse, we observe a strong correlation of ejection parameters: the spread of the ejection angle and thesize of particles increases while the number of particles and their velocity decreases. This correlation is tentatively
linked to the explosion dynamics of gas pockets at the surface, where maximum pressure differential is initiallyreleased through a small, ventral opening that gets wider with time, with possible effects of inter-particle collisions
also playing a role.
At the time scale of the whole explosion, ejection angle is a reflection of the overall vent orientation. The temperatureof the bombs and ash decrease over time and height above the vent, more slowly for the bombs, to be comparedwith theoretical predictions. The total mass of the pyroclasts ejected during a single pulse ranges from tens of kg toseveral tons, while the comulative one for an explosion can reach hundreds of tons. The ejection mass rate tends
to decrease during one explosion, suggesting that, despite the presence of ejection pulses, each explosion still
represent one well-identified and impulsive energy release event.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

873

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O13

Room A1

Date/Time: July 24 12:00-12:15

Using infrasound to infer volcanic jet parameters: revisiting acoustic power vs. jet
velocity scaling laws
Robin S Matoza1 , David Fee2 , Kent L Gee3 , Tracianne B Neilsen3 , Darcy E Ogden1
1

Scripps Institution of Oceanography, UC San Diego, La Jolla, California, USA, 2 Geophysical Institute,
University of Alaska Fairbanks, Fairbanks, Alaska, USA, 3 Department of Physics and Astronomy,
Brigham Young University, Provo, Utah, USA
E-mail: rmatoza@ucsd.edu

A basic goal of volcano acoustics is to relate observed airborne acoustic signals (usually infrasound) to theeruptive processes generating them. A quantitative link between a volcanic jet flow and its radiated infrasoundwould allow volcanic jet parameters to be inferred from infrasound data. A promising approach is to use the resultsfrom man-made jet-noise studies as a starting model for understanding the infrasound produced by the larger andmore complex volcanic jet flows, assuming that the source mechanisms are analogous. A classic paper by Woulff
and McGetchin [1976] introduced the idea of using observed acoustic power P to infer volcanic gas exit velocity
U . They proposed scaling laws of the form P ∼ U n , where the exponent n = 4, 6, or 8 for equivalent monopole,
dipole, and quadrupole sources, respectively. This formulation was based on the prevailing acoustic analogy of jet
noise. However, jet noise research has changed dramatically since then with the discovery of coherent structuresin turbulence. Jet-noise studies in the last decade have largely abandoned the idea that jet noise is composed ofequivalent monopoles, dipoles, and quadrupoles. New empirical scaling laws have been proposed for pure-air jet
flows based upon detailed laboratory studies. The new scaling laws take into account the strong temperature anddirectional dependence of jet noise. We discuss the implications of these results for volcano acoustics. We explore
the basic issues with trying to infer gas exit velocity from acoustic power using examples of volcano-acoustic data,
as well as acoustic recordings of rocket and military aircraft jet noise. This work demonstrates that Woulff and
McGetchin’s formulation can lead to large errors when inferring eruption dynamics from infrasound. We propose areplacement framework based on modern aeroacoustics research, which is being developed through quantitative
integration of field, numerical, and laboratory studies and could lead to a more accurate relationship between
volcanic infrasound and eruption column parameters.

Woulff, G., and T. R. McGetchin (1976). Acoustic Noise from Volcanoes: Theory and Experiment. Geophys. J. R.
astr. Soc. 45, 601-616.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

874

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4A2_3E-O14

Room A1

Date/Time: July 24 12:15-12:30

Infrasonic Crackle from the 2011 Eruption of Nabro Volcano, Eritrea: Evidence forSupersonic Jet NoiseDavid Fee1 , Robin Matoza2 , Kent Gee3 , Tracianne Neilsen3 , Darcy Ogden2
1

Geophysical Institute, Alaska Volcano Observatory, University of Alaska Fairbanks, USA, 2 Institute ofGeophysics and Planetary Physics, Scripps Institution of Oceanography, USA, 3 Department of Physics
and Astronomy, Brigham Young University, USA
E-mail: dfee@gi.alaska.edu

An understanding of volcanic jets is critical to determining eruption column dynamics and mitigating volcanic
hazards. However, volcanic jets are inherently difficult to observe directly due to their violence, opacity, andcomplex multi-phase and multi-component flow features. Recent work has shown similarities between the soundproduced from explosive volcanic jets and man-made jet engines and rockets [Matoza et al., 2009]. We show that
infrasound generated by the eruption of Nabro Volcano, Eritrea has waveform features highly similar to waveforms
associated with the crackle phenomenon uniquely produced by supersonic jet engines and rockets. Crackle ischaracterized by repeated asymmetric pressure pulses with higher-amplitude compressions than rarefactions andcan be quantified by the skewness (a measure of the asymmetry of the waveform probability density function).
The infrasonic crackle from Nabro reported here strongly indicates that infrasound from some volcanic eruptions
is produced in similar ways to man-made jet noise from heated, supersonic jet engines and rockets. Noisesources and flow dynamics of jet engines and rockets are better characterized and understood than volcanic jets,suggesting volcanologists could utilize the modeling and physical understandings of man-made jets.
Nabro Volcano, Eritrea erupted explosively on 12 June 2011 and injected vast quantities of SO2 into the upper
troposphere and stratosphere, disrupted air traffic, and severely affected communities in this remote region.
Significant infrasound was recorded by two infrasound arrays: IS19 (Djibouti, 264 km) and IS32 (Kenya, 1708 km).
The IS19 infrasound array detected the eruption with high signal-to-noise and provides the most detailed eruption
chronology available, including eruption onset, duration, and changes in intensity. As seen in numerous otherstudies [Fee and Matoza, 2013], sustained low-frequency infrasound from Nabro is coincident with high-altitude
emissions. The unique, distinctive infrasonic crackle from Nabro highlights the potential to use infrasound to
determine some volcanic jet characteristics and parameters such as velocity, mass eruption rate, temperature,etc. Additionally, we reiterate the potential to use infrasound as a real-time, remote means to detect hazardous
emissions, particularly in remote and poorly monitored regions.

Fee, D. and Matoza, R.S., 2013.

An overview of volcano infrasound: From hawaiian to plinian, local to

global. Journal of Volcanology and Geothermal Research, 249: 123-139, doi: 10.1016/j.jvolgeores.2012.09.002.

Matoza, R.S., Fee, D., Garces, M.A., Seiner, J.M., Ramon, P.A. and Hedlin, M.A.H., 2009.
noise from volcanic eruptions. Geophys. Res. Lett., 36(L08303) doi:10.1029/2008GL036486.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

875

Infrasonic jet

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O15

Room A1

Date/Time: July 24 15:00-15:15

A-Train satellite observations of young volcanic eruption clouds
Simon A. Carn1 , Fred J. Prata2 , Kai Yang3 , William I. Rose1
1

Dept. of Geological and Mining Eng. and Sciences, Michigan Technological University, Houghton, MI,
USA, 2 Norwegian Institute for Air Research, Kjeller, Norway, 3 Dept. of Atmospheric and Oceanic
Science, University of Maryland, College Park, MD, USA
E-mail: scarn@mtu.edu

NASA’s A-Train satellite constellation (including the Aqua, CloudSat, CALIPSO, and Aura satellites) has been flying
in formation since 2006, providing unprecedented synergistic observations of numerous volcanic eruption clouds invarious stages of development. Measurements made by A-Train sensors include total column SO2 by the ultraviolet(UV) Ozone Monitoring Instrument (OMI) on Aura, upper tropospheric and stratospheric (UTLS) SO2 column
by the Atmospheric Infrared Sounder (AIRS) on Aqua and Microwave Limb Sounder (MLS) on Aura, ash massloading from AIRS and the Moderate resolution Imaging Spectroradiometer (MODIS) on Aqua, UTLS HCl columns
and ice water content (IWC) from MLS, aerosol vertical profiles from the Cloud-Aerosol Lidar with Orthogonal
Polarization (CALIOP) instrument aboard CALIPSO, and hydrometeor profiles from the Cloud Profiling Radar (CPR)on CloudSat. The active vertical profiling capability of CALIPSO, CloudSat and MLS sychronized with synoptic
passive sensing of trace gases and aerosols by OMI, AIRS and MODIS provides a unique perspective on the
structure and composition of volcanic clouds. A-Train observations during the first hours of atmospheric residence
are particularly valuable, since in-situ sampling of fresh eruption clouds is highly challenging, and yet the fallout,segregation and stratification of material in this period determines the concentration and altitude of constituentsthat remain to be advected downwind. This represents the eruption ’source term’ essential for dispersion modeling,and hence for aviation hazard mitigation. In this presentation we focus on A-Train data collected during eruptions ofRedoubt (March 2009), Eyjafjallajökull (April 2010) and Grimsvötn (May 2011), supplemented with high-temporal
resolution SEVIRI measurements of ash mass loading in the Eyjafjallajökull plume. The A-Train data provide
unique evidence for ash aggregation or hydrometeor-enhanced ash loss in the Redoubt and Eyjafjalljökull plumes,
perhaps enhanced by the prevailing meteorological conditions in the latter case. We also present results from a
UV ash retrieval algorithm that provides new constraints on ash mass loading in volcanic plumes, to complement
commonly used IR retrieval techniques. Although of limited operational use due to data latency issues, the A-Trainobservations provide unique insights into the complex evolution of volcanic plumes after eruption.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

876

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O16

Room A1

Date/Time: July 24 15:15-15:30

Source conditions and eruptive processes governing the injection of volcanic ash during
the 2009 eruptions of Redoubt volcano, Alaska
Alexa R Van Eaton1 , Larry G Mastin2 , Amanda B Clarke3 , Kristi L Wallace4 , David P Schneider4 ,Michael Herzog5
1

USGS, Cascades Volcano Observatory, Vancouver, WA and SESE, Arizona State University, Tempe,
AZ, USA, 2 U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, WA, USA, 3 School ofEarth and Space Exploration, Arizona State University, Tempe, Arizona, USA, 4 U.S. Geological Survey,
Alaska Volcano Observatory, Volcano Science Center, Anchorage, Alaska, USA, 5 Centre for
Atmospheric Science, University of Cambridge, UK
E-mail: alexa.vaneaton@gmail.com

We present an integrated dataset combining information from field deposits, remote sensing and eruption column
modeling of the 2009 eruptions from Redoubt volcano, Alaska. The nineteen major ash-generating explosions
between 15 March and 4 April 2009 deposited a bulk ash volume of approximately 0.05 km3 . Explosive events
5 and 19, in particular, were documented with high-resolution satellite, airborne thermal infrared, and Doppler
radar, and then linked with field deposits to establish the spatial distribution and vertical structure of the volcanic
plumes. A key focus of this study is to establish the impact of magma-water interaction, followed by abundant ash
aggregation, on the overall ascent of the volcanic clouds and corresponding ash transport. Additional near-vent
processes, such as partial column collapse and interaction between buoyant and non-buoyant cloud components
are also assessed. Using detailed analysis of radar and satellite imagery, local weather conditions and examinationof preserved ash aggregates, we develop a comprehensive picture of the eruption source conditions and plumedynamics that impacted volcanic ash dispersal. Preliminary simulations using the Active Tracer High-resolution
Atmospheric Model (ATHAM) provide insights into the microphysical structure of the Redoubt clouds, highlighting
links between the volcanic and meteorological feedbacks (e.g., surface water versus atmospheric moisture andvolcanic exit velocities versus ambient wind fields) involved in ash cloud injection, transport and sedimentation.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

877

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O17

Room A1

Date/Time: July 24 15:30-15:45

Meteorological interactions with volcanic plumes in the moist tropics: implications forvolcanic plume monitoring
Andrew Tupper
Bureau of Meteorology, Australia
E-mail: a.tupper@bom.gov.au

The development of the International Airways Volcano Watch in the early 1990s created an operational requirement
for real time global monitoring for volcanic ash at all observable concentrations (more recently formalised as visible
or discernable ash through the work of the International Volcanic Ash Task Force). One of the more interestingareas of the world to do that has been the moist tropics, with many active volcanoes, relatively poor seismic
monitoring, and a highly active atmosphere dominated by deep convection.

The frequency of showers and thunderstorms (particularly around volcanoes and other mountains), poor
observing conditions on the ground, satellite obscuration by long-lasting cirrus anvils, and challenges in funding
and maintaining ground based infrastructure such as radar and lidar together mean that the occurrence andheights of volcanic plumes have certainly been under observed in the moist tropics. Volcanic Ash Advisory Centre
data also demonstrates a strong observational bias towards the drier seasons. As a result, even large eruption
plumes such as from the 2010 eruptions of Merapi in Indonesia can be very difficult to monitor.

In addition, within a moist tropical environment there is an active interplay between active volcanoes andthe meteorological environment. In an unstable or potentially unstable environment, tropical convection to highaltitudes (17+ km) is frequently triggered by very subtle influences such as low level sea breezes or differential
heating. Modelling suggests and observations demonstrate that active volcanoes, with a range of influences
extending to the very unsubtle, can act as triggers to produce volcanic cumulonimbus such as those observed at
Pinatubo, or volcanic plumes that have been very significantly increased in height and in ice content through moist
convective processes. Eruption heights tend to cluster near the height of the tropical tropopause; relatively weak
volcanic eruptions can trigger deep tropospheric convection that transports volcanic material to the tropopause or
above. Because of the role of hydrometeors in enhancing particle aggregation and removal, the smaller modelled
eruptions also produce a relatively small proportion of fine ash in the umbrella cloud compared to eruptions in a
dry atmosphere.

It is therefore difficult to reliably infer the strength of a tropospheric or lower stratospheric volcanic plume in
the moist tropics using its reported height alone. Additional volcanological and meteorological observations,
including seismic, visual, lidar and radar observations, and geostationary remote sensing can be added to satellite
height observations to assist in rapidly assessing eruption magnitude and the real-time response required.
Close collaboration between the volcanological and meteorological science communities will help to attain these
additional observations on a routine, operational basis.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

878

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O18

Room A1

Date/Time: July 24 15:45-16:00

Inverting for hourly volcanic SO2 flux using plume satellite imagery andchemistry-transport modelling: application to the 2010 Eyjafjallajökull eruption
Marie Boichu1 , Laurent Menut1 , Dmitry Khvorostyanov1 , Lieven Clarisse2 , Cathy Clerbaux3 ,Pierre-Francois Coheur2
1

IPSL, Laboratoire de Meteorologie Dynamique, Ecole Polytechnique, France, 2 Universite Libre deBruxelles, Belgium, 3 IPSL, LATMOS, Universite Paris 6, France
E-mail: mboichu@lmd.polytechnique.fr

Depending on the magnitude of their eruptions, volcanoes impact the atmosphere at various temporal and spatial
scales. The volcanic source remains the major unknown to rigorously assess these impacts. At the scale of an
eruption, the limited knowledge of source parameters, including time-variations of erupted mass flux and emission
profile, currently represents the greatest issue that limits the reliability of volcanic cloud forecasts. However, various
satellite and remote sensing observations of distant plumes are available today and indirectly bring informationon these source terms. Here, we develop an inverse modeling approach combining satellite observations of the
volcanic plume with an Eulerian regional chemistry-transport model (CHIMERE) to better characterise the volcanic
SO2 emissions during an eruptive crisis. The 2010 Eyjafjallajokull eruption is a perfect case-study to apply thismethod as the volcano emitted substantial amounts of SO2 during more than a month. We take advantage of
the SO2 column amounts retrieved from a vast set of observations by the IASI (Infrared Atmospheric Sounding
Interferometer) instrument on board the METOP-A satellite to reconstruct retrospectively the time-series of the SO2flux emitted by the volcano with a temporal resolution of about 2 hours, spanning the period from 1 to 12 May 2010.
The initialisation of chemistry-transport modelling with this reconstructed source allows a reliable simulation of theevolution of the long-lived tropospheric SO2 cloud over thousands of kilometres. Heterogeneities within the plume,
which result from the temporal variability of the emissions, are also correctly tracked over a time scale of a few
days. The robustness of our approach is also demonstrated by the broad similarities between the SO2 flux history
determined by this study and the ash discharge behaviour estimated by other means during the phases of highexplosive activity at Eyjafjallajokull in May 2010. Finally, we show how a sequential IASI data assimilation allows fora substantial improvement in the forecasts of the location and concentration of the plume compared to an approachassuming constant flux at the source. As the SO2 flux is a good indicator of the volcanic activity, this approach isalso of interest for volcanologists to monitor from space poorly instrumented volcanoes.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

879

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O19

Room A1

Date/Time: July 24 16:00-16:15

Rotating volcanic plumes
Pinaki Chakraborty1 , Gustavo Gioia1 , Susan Kieffer2
1

Okinawa Institute of Science and Technology, Japan, 2 University of Illinois, USA
E-mail: pinaki@oist.jp

In contrast to the classical models of strong volcanic plumes, where the plume is assumed to be non-rotating, we
provide direct evidence that the entire plume rotates about its axis. By drawing analogy with the meteorologicalphenomenon of a tornadic thunderstorm, we argue that the plume rotates due to the interaction between the
updraft in the plume and the shear in the atmosphere, resulting in the formation of a cyclonically rotating columnar
vortex—a "volcanic mesocyclone." The volcanic mesocyclone provides a unified explanation to a disparate set ofpoorly understood phenomena in volcanic plumes, including the development of lobate umbrellas, the spawningof tornadoes, and the formation of lightning sheaths. We conclude by illustrating how the volcanic mesocyclone
entails a fundamentally different plume dynamics than that inferred from the classical models.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

880

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O20

Room A1

Date/Time: July 24 16:15-16:30

The 1815 Tambora distal ash fall: Implications for transport and deposition on land andin the deep sea
Jessica Kandlbauer1 , Steven N Carey2 , R Stephen J Sparks1
1

University of Bristol, United Kingdom, 2 University of Rhode Island, USA
E-mail: jessica@aeroscience.ch

The 1815 Tambora eruption deposited an estimated 100 km3 of tephra over large parts of Indonesia and theadjacent sea, providing a good example to compare the grain size distribution of distal ash samples on landwith ash recovered from the deep sea. Subsequently, grain size analysis can contribute information on thetransport and distribution during the Tambora eruption. The results show a continuous trend towards a finer-grainedash distribution with distance, indicating that the depositional environment does not influence the ash particle
distribution. Indeed the finest ash particles (2-4 µm) are still present in the same relative proportions in the deepsea ash layers as seen on land. The gravity current model has been modified to simulate the ash transport in theTambora cloud, and includes now an ash fraction depositing while the cloud advances, as well as an ash fraction
accounting for the remaining ash in the cloud falling out once the eruption stops. The contribution of the twocomponents depends mainly on particle fall velocity and eruption duration, as fall velocity and/or eruption duration
increases, the amount of ash depositing from the advancing cloud increases. With the eruption duration (24 hours)
and cloud velocity (1.5-2.5x1011 m3 /s) calculated from historical records, and assuming a 3h Plinian and 21h
co-ignimbrite phase, the new model estimate reduces the mean absolute error by half if both ash components are
considered©IAVCEI 2013 Scientific Assembly. All rights reserved.

881

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4P1_3E-O21

Room A1

Date/Time: July 24 16:30-16:45

Scaling of volcanic eruptions
Jonas Eliasson1 , Nario Yasuda2 , Andreas Vogel3 , Masato Iguchi2
1

Research professor Earthquake Engineering Institute University of Iceland, Iceland, 2 Professor
Disaster Prevention Research Institute, University of Kyoto, Japan, 3 Researcher Institue forEnvorinmental Measurement Technology, University of Applied Sciences, Germany
E-mail: jonase@hi.is

Volcanic eruption where the plume is carried away with the wind can be geometrically similar to another eruptionin length scale and time scale that are determined by the plume height and the wind velocity. They can also
be dynamically similar if the dispersion factor scales according to the same scales. The median grain size in
different distances from the crater scale according to a self similarity rule so 1 over(dist) is a measure for the grain
size. Different phases of the same eruption need to be scaled to same plume height and wind velocity to find theself-similarity rule, this is demonstrated using data from the Eyjafjallajokull eruption in 2010. A satellite photo of
the Eyjafjallajokull plume is used to demonstrate a new method of estimating the dispersion coefficient from thelinear expansion rate of the visible boundary of the plume. Finally a measurement of in-situ ash concentrations in
a volcanic cloud from Sakurajima mountain is scaled up to a larger cloud using wind from the east and a plumemagnitude relation recommended by Sakurajima Volcanological Observatory.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

882

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P1

Date/Time: July 24 Poster

Probabilistic volcanic ash dispersal modelling using PF3D: An example from Gunung
Ciremai, West Java Indonesia
Adele N Bear-Crozier1 , Nugraha Kartadinata2 , Anjar Heriwaseso2
1

Geoscience Australia, Australia, 2 Centre for Volcanology and Geohazard Mitigation, Indonesia
E-mail: Adele.Bear-Crozier@ga.gov.au

Volcanic ash represents a serious hazard to communities living in the vicinity of active volcanoes in developing
countries like Indonesia. Geoscience Australia, the Australia-Indonesia Facility for Disaster Reduction (AIFDR) andthe Indonesian Centre for Volcanology and Geohazard Mitigation (CVGHM) have adapted an existing open source
volcanic ash dispersion model for use in Indonesia. The core model is the widely used volcanic ash dispersion
model FALL3D. A python wrapper has been developed, which simplifies the use of FALL3D for those with little or nobackground in computational modelling. An application example is described here for Gunung Ciremai in West Java,
Indonesia. Scenarios were run using eruptive parameters within the acceptable range of possible future events forthis volcano, granulometry as determined through field studies and a meteorological dataset that represented acomplete range of possible wind conditions expected during the dry and rainy seasons for the region. Implications
for varying degrees of hazard associated with volcanic ash ground loading on nearby communities for dry versus
rainy season wind conditions is discussed. Communities located on the western side of Gunung Ciremai are highly
susceptible to volcanic ash ground loading regardless of the season whereas communities on the eastern side arefound to be more susceptible during the rainy season months than during the dry. This is attributed to prevailingwind conditions during the rainy season that include a strong easterly component. These hazard maps can be used
for hazard and impact analysis and can help focus mitigation efforts on communities most at risk.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

883

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P2

Date/Time: July 24 Poster

Infrasound of sustained volcanic eruptions, a laboratory and field study
Elizabeth E C Swanson, Theunissen Raf, Phillips C Jeremy, Rust Alison
University of Bristol, uk
E-mail: gleecs@bristol.ac.uk

Volcanic plumes represent a significant hazard both near to and at distance from source. Unfortunately, hightemporal resolution monitoring, especially in the case of more remote systems, is often lacking. Due to their
turbulent nature, these plumes are a substantial source of sub 10 Hz sound; meaning infrasonic methodology has
the potential to fill the monitoring void. Recent studies of volcano infrasound have drawn upon research from theaero-acoustics industry, fitting the large scale jet noise spectrum (LSS) to that observed during column generating
eruption events (Matoza et al 2011). However, due to the differences between volcanic plumes and the pure gas
jets, from which the aero-acoustics spectra are created, further laboratory studies are required to investigate thetrue source of the volcanic signals.
In the absence of industrial standard anechoic chambers, and indeed in terms of the field application ofexperimental findings, successful source localisation methods are paramount. Adaptive beamforming, as opposedto the commonly used delay and sum methodology, offers a means to achieve the required spatial resolution of thegenerated sound field.
In a set of experiments at the University of Bristol, an omni-directional microphone array was used to demonstrate
the ability of the adaptive method. The acoustic signatures of a series of subsonic jets were recorded using the
GFAL 36 and 48 element GFAL Acoustic Camera arrays and subsequently analsyed using both GFAL and in house
built software. The experiments were housed in a purpose built test structure lined with 10cm pyramid foam. A flow
settling chamber and baffle box, upstream of the test section, were used to prevent the transmission of rig noise
to the recorded signals. A synchronous PIV dataset was also obtained enabling visualisation of the jet structure.
The level of PIV seeding was varied to enable assessment of the effect of particulate matter upon the acoustic
signature. Furthermore a range of different nozzle shapes have been test to better reproduce the fully turbulent
conditions of volcanic jets.
In addition to the laboratory dataset, the beamforming methodology has been applied in the field setting at
Santiaguito volcano, Guatemala. A 4 element infrasound array consisting of a 1 Chaparral Physics Model 25Vx
and 3 Hyperion Technology IFS-3114 Infrasound Sensors with an inter-element spacing of 100 m was installedat the Santiaguito Volcano Observatory 6 km from the vent and used to retrieve dominant source locations andpowers.
The adaptive methods employed here offer the potential to remove dominate acoustic sources, which preliminary
findings show to be related to the nozzle/vent exit. Such source removal has the potential to reveal any weakerflow related sources which may be present.

REFERENCES: Matoza,R., et al (2009) Geophysical Research Letters Vol, 36 L08303.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

884

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P3

Date/Time: July 24 Poster

3D Lattice-Boltzmann strategies: New insights into Volcanic Jet Dynamics andInfrasoundFederico Brogi1 , Costanza Bonadonna1 , Maurizio Ripepe2 , Bastien Chopard1 , Jonas Latt1 , Orestis
Malaspinas1 , Jean-Luc Falcone1
1

University of Geneva, Switzerland, 2 University of Florence, Italy
E-mail: Federico.Brogi@unige.ch

Recent studies highlighted the great potential of infrasound measurements for real time detection of volcanic
plume source parameters. This is especially relevant in the case of bent over plumes, where the relation between
mass eruption rate and plume height is made more complex by the interaction with the surrounding wind field andclassical formulation do not apply. Pressure variation detected through acoustic data could be used to determine
the exit velocity of the gas jet, which can be related to mass eruption rate, based on the geometric constrainof the vent and the mixture density. However, a source theory for volcanic infrasound is far from being complete.
Woulff and McGetchin (1976), based on Lighthill’s classical source model theory, proposed that small-scale volcanic
jet turbulence may produce infrasound waves as quadrupole or dipole-type source when boundaries or solid
particles are present. More recently, Matoza et al. (2009) on the base of the spectral shape infer large-scale
turbulence to explain the infrasonic signal generated by large explosive eruptions at Mount St. Helens (USA) and
Tungurahua (Ecuador). Even if the gas-thrust region of large Vulcanian and Plinian eruptions is made up by aturbulent free-shear-jet flow the application of the classical source models is challenged by sound radiation patternmeasurements.
A better knowledge of the link between the acoustic radiation and actual volcanic fluid dynamics processes isrequired. New insigths in this subject could be given by the study of realistic areoacustics numerical simulation ofa volcanic jet. Lattice Boltzmann strategies provide the opportunity to devolop an accurate, computationally fast,
3D physical model for a volcanic jet and wave propagation. Our work mainly focuses on developing and validatingsuch numerical model to determine when and how classic model source theory can be applied to explain volcanic
infrasound data. Here we present the first test results for our model.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

885

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P4

Date/Time: July 24 Poster

Effects of vent asymmetry on plume dynamics for explosive eruptions
Shi Sim, Darcy Ogden
Scripps Institution of Oceanography, USA
E-mail: shsim@ucsd.edu

Models of volcanic eruptions are typically based on symmetric vent and conduit geometries. However, in natural
settings, these features are rarely perfectly symmetric. For example, the May 18, 1980 eruption of Mount St
Helens (MSH) took place through a highly asymmetrical crater due to the preceding landslide and subsequent
vent erosion. In supersonic, high pressure eruptions, such as what may have occurred at MSH, vent and crater
asymmetry can strongly affect the directionality of the gas-thrust region. These effects on eruption
direction have implications for spatial distribution of the initial blast phase, tephra fallout patterns, and plume stability.

Here we explore flow dynamics resulting from supersonic, high pressure eruptions though asymmetric volcanic
vents using a combination of numerical and semi-analytic methods. Our time-dependent numerical simulations
are performed using CartaBlanca, a Java based simulation tool for non-linear physics from Los Alamos National
Laboratory. Preliminary results from these numerical tests suggest that vent asymmetry may have a first-ordereffect on the dynamics of the initial phases of explosive eruptions. Semi-analytic methods are used to determine
the combinations of eruption explosivity (overpressure) and vent asymmetry (shapes) where this effect will be mostpronounced.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

886

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P5

Date/Time: July 24 Poster

Smoluchowski kernels for dry particle aggregation: Cellular Automata and experimental
investigations
Eduardo Rossi1 , Gholamhossein Bagheri1 , Costanza Bonadonna1 , Jean Luc Falcone2 , Bastien
Chopard2 , Piero Pontelandolfo3 , Patrick Haas3
1

Earth Sciences Department, University of Geneva, Geneve, Switzerland, 2 Computer Sciences,
University of Geneva, Geneve, Switzerland, 3 CMEFE University of Applied Sciences Western
Switzerland in Geneva, Geneve, Switzerland
E-mail: Eduardo.Rossi@unige.ch

Particle aggregation is considered as a key process that may affect dispersal and sedimentation of volcanic ash,with significant implications for the associated hazards. Smoluchowski coagulation equation is commonly used todescribe the expected time evolution of the size distribution of ash particles that can collide and stick together.
This approach is based on the use of theoretical kernels that come from the theory of diffusion and turbulent
motion of charged and uncharged particles. We propose a wind-tunnel experiment to estimate Smoluchowski
kernels and compare the results with numerical simulations. We focused mainly on dry ash aggregation dominatedby electrostatic charges. Particles are suspended in a vertical wind tunnel for a period of time sufficient to create
collisions and to produce consequential electrostatic charging by friction. Temperature and humidity are parametersthat can affect the results so are kept under control in the device during the experiments. Using a high-speed
camera and a dedicated Particle Tracking Velocimetry software is then possible to monitor the change of the initial
mass distribution in time due to aggregation. Knowing the time evolution of aggregates gives us the opportunity
to estimate empirically the kernels of the Smoluchowski coagulation equations and to make some comparisonswith the theoretical kernels for a pure dry phenomenon dominated by electrostatic forces. Moreover it is possible
to have a first validation of the use of Smoluchowski coagulation equations with a real laboratory experiment. The
experimental kernels were integrated within a dedicated cellular automata model for ash sedimentation. This study
represents a first step to merge theoretical and experimental studies of particle aggregation.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

887

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P6

Date/Time: July 24 Poster

Water-isotope evidence of a persistent plume observed in snow and ice samples at
Erebus volcano, Antarctica
Aaron G Curtis1 , Philip R Kyle1 , Laura Jones1 , Melissa Kammerer1 , Andrew Campbell1 , Richard
Arimoto2
1

New Mexico Institute of Mining and Technology, USA, 2 Carlsbad Environmental Montoring andResearch Center, USA
E-mail: aarongc@nmt.edu

A volcanic δ 2 H / δ 18 O signature is present in snow samples and cores through the walls of fumarolic ice towers
on the flanks of Erebus volcano, Antarctica. Of 213 samples analyzed, 61% plotted outside the field of all isotopic
measurements of snow recorded for the entire continent of Antarctica. The isotopic data for Erebus samples are
shifted from isotopically light Antarctic snow towards a typical magmatic water box.

The signature is thought to result from the release of magmatic water from Erebus’ persistently degassing
lava lake. Ice crystals may nucleate and fall from the plume directly, or plume vapor may mix with storm fronts andenrich meteoric snow. Fumarolic release of water from the volcano’s flanks may also contribute to the signature.
Samples from ice towers above fumarolic vents do not show a significantly higher enrichment than other snow
samples, indicating that the plume is the main source of volcano water.

S, Cl, and F concentration was measured for the majority of the snow samples.

Notably, there is poor

spatial correspondence between the anionic volcanic signature and the water isotope volcanic signature. The
transport and deposition mechanisms for plume water appear to be decoupled ffrom those of gaseous aerosols in
the plume.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

888

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P7

Date/Time: July 24 Poster

Towards improved characterisation of volcanic ash
Emma J Nicholson1 , Katharine V Cashman1 , Alison C Rust1 , Sigurdur R Gislason2
1

University of Bristol, Department of Earth Sciences, U.K., 2 University of Iceland, Institute of Earth
Sciences, IcelandE-mail: en12525@bristol.ac.uk

Explosive volcanism can generate large volumes of volcanic ash, with potentially significant economic andenvironmental implications. Recent eruptions, such as that of Eyjafjallajokull in 2010, have highlighted gaps in
our knowledge regarding both the fragmentation mechanisms that produce ash and their effect on the resulting
size distributions and morphologies of erupted pyroclasts. Mafic eruptions, in particular, exhibit a wide range oferuption styles that generate pyroclasts with highly variable sizes, shapes, vesicularities and crystallinities. We
are investigating links between eruption style and pyroclast characteristics, with the goal of using these data bothto gain insight into the processes governing fragmentation and to develop characteristic source parameters fordifferent eruption conditions.

The 2011 subglacial eruption of Grimsvotn, Iceland, involved the explosive interaction of volatile-rich basaltic
magma with subglacial meltwater. The tephra produced in this eruption contains a high proportion of fine ash, with
90 percent of grains less than 100 microns in diameter, and is texturally diverse. The ash-fall samples used in thisstudy were collected 50-115 km southwest of the vent immediately following the eruption. We explore variation inquantitative shape parameters as a function of both grainsize and transport distance using multiple image analysis
techniques, including Morphologi and Scanning Electron Microscopy (SEM). Sample componentry comprises two
dominant particle classes (dense/vesicular) that can be further subdivided (blocky and platy/highly, moderate, andelongate vesicular), with less than 5 percent crystalline material. Systematic trends in the relative proportionsof each particle class are evident within the fine ash fraction (10-125 microns), the most striking of which is theincrease in the percentage of dense relative to vesicular grains with decreasing grainsize.

Vesicle size distributions (VSDs) were measured on vesicular clasts and fragments where greater than 50
percent of individual bubble walls were preserved. VSD modes lie between 30 and 50 microns. By combining
morphological data on particle shapes with textural data on vesicular fragments we can reconstruct the state of themagma at the point of fragmentation. Fragmentation style appears strongly controlled by the VSD: the dominantparticle morphology, as measured by both componentry and shape parameters, changes significantly as theparticle size approaches the modal size of the vesicle population. The presence of several different morphologicalcomponents suggests fragmentation of an inhomogeneously vesicular primary magma, such as the internal
textures commonly observed within Peles tears quenched from Hawaiian fire fountains. Determining how theparticle size and shape distributions of volcanic ash are linked to the style of magma fragmentation will guide thedevelopment of characteristic input parameters for ash dispersion models.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

889

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P8

Date/Time: July 24 Poster

Effects of subgrid-scale turbulent models on spatial structure in large-eddy simulation ofan eruption column
Hitoshi Suto, Yasuo Hattori, Kiyoshi ToshidaCentral Research Institute of Electric Power Industry, JAPANE-mail: suto@criepi.denken.or.jp

In the transport of volcanic ash in an explosive eruption, the turbulence is one of the important elements which
determine the eruption styles such as an eruption column and a pyroclastic flow.

The conventional steady

one-dimensional models for an eruption column assume that the effect of turbulence is represented as a constantin a theoretical formula, although it is indicated that the assumption has measurable uncertainty (Suzuki et al. 2005,
Ishimune 2006). In recent years, unsteady three-dimensional eruption column models, which represent turbulence
more directly, have been developed. However, the turbulence modeling in the transports of gas and pyroclastic
materials are left unclarified. For instance, subgrid-scale (SGS) turbulence stresses are differently modeled in
Neri et al. (2007) and in Suzuki and Koyaguchi (2010), although the contribution of SGS models to simulations ofreal-scale eruption column and the consequences of different SGS models applied are not well understood. In thisresearch, the unsteady three-dimensional simulation code for an eruption column is developed. The effects of SGS
models are discussed through the comparisons between the simulation results using two kinds of the models.
In this code, the model concept of Neri et al. (2007) is adopted, which is advantageous in its applicability to various
volcanic styles and to the transport of pyroclastic materials of various sizes. The large-eddy simulation (LES)
technique based on a SGS model is adopted as expression of turbulence. The gas component and pyroclastic
materials of various diameters are classified into two or more phases (the multi-fluid approximation). The SGS
model is a part of the submodels in the stress term and the diffusion term in the basic equations. As the SGS
models, the Smagorinsky model, which is generally used, and the Yuu model, in which the effect of SGS drag isconsidered (Yuu et al. 2001), are adopted for the gas phase, and the equation proposed by Hinze, in which therelation between the relaxation time of particles and the temporal duration of vortex is considered (Hinze 1975), forthe particle phases.
The following results were obtained from the LES results for an eruption column and laboratory simple flows: (1)When fine grid systems that enable the capture of the major spectral bands in a turbulence field are used in thesimulation, the LES results show general agreement with those of the existing experiments and the theoreticalsolution in laboratory simple flows, and qualitative agreement of cloud shapes with those of the one-dimensionalmodel in an eruption column. (2) The SGS models for gas and particle phases cause variations in eruption cloudshape. Possible causes of the variations are the strong dependence of the whole diffusion process in the LES ofan eruption column on the SGS model used and the high sensitivity of the eruption cloud shape to the strength of
turbulent diffusion.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

890

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P9

Date/Time: July 24 Poster

Reconstruction of volcanic plume properties through integration of infrared imagery andanalytical one-dimensional models
Sebastien Valade1 , Matteo Cerminara2
1

LMV, Universite Blaise Pascal, 5 rue Kessler, 63000 Clermont-Ferrand, France, 2 Scuola Normale diPisa, Italy
E-mail: s.valade@opgc.univ-bpclermont.fr

The most effective approach to understanding the dynamics of volcanic ash plumes is through synergy of dataacquisition (in field and/or laboratory settings) and data modeling (with analytical and/or numerical methods). The
aim of this study is to explore the feedbacks between these two aspects, using infrared thermal videos of short-lived
ash plumes imaged at Santiaguito (Guatemala). The first step was to carry out a stationary analysis of the video
data, by filtering the time-dependent dynamic fluctuations of the plume. To do so, we reconstructed a mean imageout of the entire movie sequence, where each pixel ascribed a time-averaged temperature. This image was thencompared with the plume characteristics predicted by mean analytical models (e.g., spreading rate and verticalvariations of temperature, velocity and particle concentration), in which electromagnetic radiation equations wereintroduced to simulate a synthetic radiometric image. The end objective is to use inversion models to recover
the best input parameters (e.g., source ash mass, particle size distribution and air entrainment coefficient) that
reproduce the observed data. The second step was to carry a time-dependent analysis of the plume dynamics.
Data processing here mainly consisted of the algorithm development to analyze the video sequences, and extract
key parameters that characterize the ash plumes through time, such as ascent velocities, volume, heat budget,
etc. These algorithms were managed using an open-source user-friendly interface plumeTracker developed in
Matlab, which can deal with a variety of video data collected at any wavelength (IR, VIS, or UV). Output was thencompared with transient integrated models, which simulate the bulk plume motion through time. The end objective
was to identify the most relevant features to track from the plume motion to inform on the source parameters, andin particular to yield the mass flux at the source.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

891

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P10

Date/Time: July 24 Poster

Three-dimensional acoustic source localization of explosion and degassing events at
Karymsky Volcano, Kamchatka, Russia.
Colin R Rowell1 , David Fee1 , Curt A.L. Szuberla1 , Kenneth M Arnoult1 , Robin S Matoza2 , Taryn M
Lopez1 , Pavel Firstov3 , Evgeniy Makhmudov3
1

Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska, USA, 2 Institute ofGeophysics and Planetary Physics, Scripps Institution of Oceanography, California, USA, 3 Kamchatka
Branch of the Geophysical Survey, Petrapavlovsk-Kamchatsky, Kamchatka, Russia
E-mail: rowell.colinr@gmail.com

Recent research has drawn links between the acoustic signals of volcanic jets and those of man-made jet engines(jet noise), but this relationship has yet to be firmly established. Turbulent jet flows have been observed to
produce acoustic signals extending from the nozzle to a finite distance downstream. One of the challenges ofobserving potential analogous acoustic sources from volcanoes is due to most microphone deployments being
below the volcanic vent and restricted to topography that is predominantly two-dimensional. At Karymsky Volcano,Kamchatka, Russia, the topography of an eroded edifice adjacent to the volcano provides a platform for the
deployment of an array of infrasound sensors in three dimensions. 5 infrasound microphones were deployed on
this eroded edifice for 11 days in July 2012. The microphone deployment spanned a volume of approximately 2
kilometers horizontally, and covering 600 meters of elevation. When permitted by weather and daylight, continuous
acoustic recording at 250 Hz was accompanied by FLIR, video, and gas emission data. During this time period,
observed activity at Karymsky Volcano consisted of periods of semi-continuous high frequency (up to about 90
Hz) jetting and degassing, punctuated by a small number of discrete ash explosions. Here we present acoustic
source localization results using a novel time-difference-of-arrival technique developed by Wilson InfrasoundObservatories. Preliminary results in horizontal space show that events are clustered about the vent in a region
140 by 310 meters across. However, vertical distributions show only one explosion event located immediately at
the vent, while other located explosions and degassing signals cluster persistently in a region between 175 and650 meters above the vent. These results can be interpreted in three ways: (1) Bias in the locator algorithm orarray geometry; (2) atmospheric or plume effects influencing sound propagation; or (3) sources decoupled fromand above the vent region. Current work will attempt to determine which of these three cases is most plausible.
This will be accomplished through forward model simulations for this array geometry, comparison with alternative
location methods such as grid-based semblance, and evaluation of FLIR and video data. Development of this 3D
localization technique may allow the identification of distinct sounds sources from volcanic eruptions. This helps torefine current understanding of the relationship between acoustic signals and the eruptive processes that generatethem, and improves the effectiveness of acoustic monitoring of volcanoes.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

892

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P11

Date/Time: July 24 Poster

Direct Numerical Simulation of (pocket-size) volcanic jets
Joern L Sesterhenn, Flavia C Miranda, Juan J Pena-Fernandez
TU Berlin, Germany
E-mail: joern.sesterhenn@tu-berlin.de

Direct Numerical Simulation (DNS) provides an accurate and well proven tool to compute flows in any detail and forevery flow quantity of interest. The model are the Navier–Stokes equations and a Lagrangian-particle model (a sixthorder compact scheme for the flow and a two way coupling for the particles in our case). No turbulence closures
are needed since the turbulence is fully resolved from the largest scales down to the dissipation range. DNS is thus
the ideal tool to study such kind of flow and reveal quantities which are not accessible in practical measurement.
The only minor glitch is, that most of us will not work long enough to see even a small strombolian eruption fully
resolved: The Reynolds-number accessible by today’s biggest supercomputers under exclusive usage for one
year is 66000 whereas a tiny volcanic jet ranges in a Reynolds number of about 500 million. Given Moore’s lawof doubling the computer power in 18 months one can predict the computability of the volcanic jet in about 45 years.

But that does not mean we should just wait: meanwhile DNS is still very useful since it provides everything
about small scale experiments which are feasible to be computed, including many quantities not accessible bymeasurement.

In this presentation, we show simulations of supersonic jets at Re=5000 using on 2 · 109 grid points and2 · 106 of particles for different pulse lengths of the event, ranging from tD/U = 1 to 30.

The flow morphology of the jet will be discused in detail and time histories of instantaneous and sampled
data like shock-cell structure, turbulence intensities and acoustic radiation will be presented.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

893

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P12

Date/Time: July 24 Poster

Premature fallout of fine ash: the role of convective instabilities
Irene Manzella1 , Costanza Bonadonna1 , Jeremy Phillips2
1

University of Geneva, Switzerland, 2 University of Bristol, United Kingdom
E-mail: irene.manzella@unige.ch

Tephra fallout is one of the most widespread natural hazards and can significantly affect several economical sectors.
In addition, volcanic fine ash suspended in the atmosphere can represent a significant threat to aviation as shownby the 2010 Eyafjallajökull eruption (Iceland). A good understanding and description of tephra dispersal is crucial
to the mitigation of the associated risk. Processes that might significantly affect sedimentation of volcanic ash andthat have not been yet well parameterized include particle aggregation and convective instabilities (gravitational
instabilities which occur at the base of volcanic clouds where a denser fluid, the ash cloud, is emplaced above
a lighter one, the atmosphere). Convective instabilities develop in series of discrete particle-rich protrusions(i.e. fingers), which seem to generate preferential paths for fine ash to settle. Both aggregation and convective
instabilities make fine particles fall closer to the vent than expected, and due to the associated high concentrationof fine ash in the fingers, aggregation processes could also be enhanced by convective instabilities.
Fingering is observed at the base of many volcanic clouds but we have been able to quantify their motion for theplume generated during the 2010 Eyafjallajökull eruption. Considering the measured finger speed and the volcano
topography we found that fingers started sedimenting at about 10 km from vent, and this distance corresponds tothe first observations of particle aggregation (Bonadonna et al. 2011).
We have conducted a series of laboratory experiments in a tank of 50x 30.3x 7.5 cm. A removable barrier wasplaced at a height of 25.1 cm to separate two different layers of fluid and ensure an impermeable separation andan initially sharp interface before the beginning of the experiments. The upper part was filled with a suspensionof water and particles; the lower part was completely filled with a denser sugar solution. Experiments consistedof removing the separation and analysing the formation of fingers. Various initial conditions were investigated(including mixed and unmixed layers) resulting in different variation of concentration with time. However, in allcases, after removing the separation, particles started to sediment at the bottom of the upper particle-rich layer
and the gravitational instabilities started developing. In all cases, results show that convective instabilities do notaffect the sedimentation rate in the upper layer but strongly affect sedimentation in the lower layer. In presence of
convective instabilities, particles reach the bottom of the tank faster than predicted by individual settling velocities.
Particle sedimentation rates in the experiments can be described using a model of dilute particle suspensions whichtakes into account the role of the interface layer between the two fluids with different density and the behaviour offingers.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

894

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P13

Date/Time: July 24 Poster

Effects of complex plume morphology on tephra dispersion modeling in ATHAM 3D
Shannon EK Nawotniak1 , Marcus I Bursik2
1

Idaho State University, USA, 2 University at Buffalo, USA
E-mail: kobsshan@isu.edu

Ambient wind conditions play a critical role in plume morphology and, therefore, tephra dispersion. Models fortephra dispersion and deposit inversion have historically been required to simplify wind-plume interactions in orderto accommodate computational expense; the Active Tracer High-resolution Atmospheric Model (ATHAM) takes
advantage of cluster computing to calculate 3D wind-plume interaction using the Navier-Stokes equations witha Lagrangian Eddy Simulation turbulence closure. With the inclusion of a large pyroclast dispersion module, it
is possible to use ATHAM to model tephra deposition from complex plume morphologies, including bent plumes
resulting from strong ambient winds. Strong low-elevation windshear or interaction with the jetstream produce
markedly different plume morphologies and mass loading in the atmosphere. The resulting deposition patterns
reflect the increased plume complexity and influence of lateral sorting of equal-mass pyroclasts, a consequence ofdiffering drag effects from horizontal flow exacerbated by the wind-plume interaction.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

895

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P14

Date/Time: July 24 Poster

Eruptions on the fast track, part a): computational routines for processing visible andthermal high-speed videos of explosive eruptions
Damien Gaudin1 , Monica Moroni2 , Jacopo Taddeucci1 , Piergiorgio Scarlato1 , Luca Shindler2
1

Department of Seismology and Tectonophysics, HP-HT Lab, INGV Roma, Italy, 2 DICEA , Sapienza
Universita di Roma, Rome, Italy
E-mail: damien.gaudin@ingv.it

Recent advancements in the use of high speed thermal and visible cameras allowed a precise quantification of key
parameters of explosive eruptions. However, the large volume of video data poses several processing issues andhinders parameter extraction. In this methodological investigation we show how computing techniques based on
Particle Image Velocimetry (PIV, measuring the displacement of sub-areas of an image between successive frames
by correlating features identified in any sub-area) and Particle Tracking Velocimetry (PTV, detecting and tracking
single particles along a series of images) allows for the automatic processing of high-speed videos and explosion
parameterization.
We developed a 3-steps automatized routine for volcanic high-speed video processing. Step 1 pre-processes theimages, removing image background with different techniques to improve image contrast and possibly accounting
for camera shaking. Step 2 involves running the custom-made PTV and PIV softwares. Step 3 processes thesoftwares outputs while operating a first filtering for numerical errors, and then operates the post-processing of theresults, where several additional filters can be applied to the results and volcanologically-relevant parameters are
finally computed. A sensitivity study was used to define the best settings for each of the above steps and their effecton output parameters.
The overall suitability of our routine and its limitations have been tested on high-speed videos of explosions ofStromboli (Italy) and Yasur (Vanuatu) volcanoes, including a variety of recording conditions and styles of explosive
activity.
From the above videos, PTV enables us to construct, for each explosion, a database including the size andtrajectory of a large number (order of 10000) of cm-to m-sized pyroclasts. From the database a broad variety
of key parameters are then extracted, from single particle ones (e.g., temperature, drag coefficient, deviation fromtheoretical ballistic trajectories), through explosion evolution ones (e.g., time variation of mean exit velocity, angle,
mass and related standard deviations), up to whole-explosion ones (e.g., grain-size distribution and total mass ofejecta, thermal to kinetic energy balance, depth of the explosion, geometry of the vent). PIV provides the velocity
vectors of diffuse features, i.e., gas and ash clouds, from which the time and space evolution of: 1) gas ejection
velocity; 2) total ejected volume of gas plus pyroclasts; and 3) plume buoyant rise can be assessed.
Automatized results are in general agreement with previous manual estimations on the same videos but on a limited
number (order of thousands) of particles, supporting the robustness of out procedure. An illustration of the varietyof the volcanological application of this routine is presented in the companion abstract Eruptions on Fast Track, partb.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

896

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P15

Date/Time: July 24 Poster

The effect of pre-existing craters on the initial development of explosive volcanic
eruptions: an experimental investigation
Jacopo Taddeucci1 , Greg A. Valentine2 , Ingo Sonder2 , James D.L. White3 , Pierre-Simon Ross4 ,Piergiorgio Scarlato1
1

HP-HT Lab, Istituto Nazionale di geofisica e Vulcanologia, Italy, 2 Department of Geology and Center
for Geohazards Studies, University at Buffalo, USA, 3 Geology Department, University of Otago, New
Zealand, 4 Institut national de la recherche scientifique (INRS), centre Eau Terre Environnement (ETE),
CanadaE-mail: taddeucci@ingv.it

Most volcanic eruptions occur in craters formed by previous activity. The presence of a crater implies specificconfinement geometries, variably filled by loose fragmental deposits, which are expected to exert a strong, yet
poorly studied, control on the violent gas expansion that drives the eruption. Here we analyze patterns of ejection
from buried explosions in analog experiments, in order to investigate how the presence of a crater and changes in
explosion depth and intensity may affect the formation of eruptive ejecta jets. Different explosive charges were
detonated at variable depth in prepared pads of granular material, resulting in variable scaled depth (charge
burial depth divided by the cubic root of charge energy). Explosions were filmed at 600 frames per second, andvideo analysis provided information on: 1) jet morphology and evolution; 2) jet vertical speed; 3) jet spread angle.
Results show that explosions with progressively smaller scaled depth produced exponentially faster-growing jetswith linearly larger spread angles. Deeper scaled depth explosions are marked by more-complex jets, featuring acentral, narrower, faster portion that pierces upward through a larger, slower annulus having a stronger componentof lateral expansion. For a fixed scaled depth, the pattern of expansion of the jet seems to be largely controlled by
the initial presence of a crater, which limits the development of a laterally expanding annulus.
The relationship between jet velocity and scaled depth holds true independently of the presence of a pre-existing
crater infill, while jet spread angle shows, overprinted on a major control exerted by scaled depth, also an effect ofthe presence of a crater. Finally, the presence of a crater around the explosion site does exert a strong control on
the expansion pattern of the jet. The complex development of explosions with both a vertically-expanding central
core and a peripheral, lateral expanding annulus seems promising for characterizing the intra-crater evolution ofan eruption. This distinction has also implications for both hazard assessments and for investigations of eruptive
products. The vertical core and radial annulus could be associated with the formation of buoyant jets and ballistic
showers, and dilute pyroclastic density currents, respectively. Since the radial annulus tends to be inhibited by thepresence of a relatively deep crater, this could promote a decrease in the occurrence of coarse-grained pyroclastic
surges (and their deposits) extending beyond a crater as an eruption and the respective crater evolve over time.
Conversely, the fallback of a vertically-focused jet could trigger a fine-grained pyroclastic surge, potentially leaving
fine-grained, bedded deposits.

©IAVCEI 2013 Scientific Assembly. All rights reserved.

897

IAVCEI 2013 Scientific Assembly - July 20 - 24, Kagoshima, Japan
Forecasting Volcanic Activity - Reading and translating the messages of nature for society

4W_3E-P16

Date/Time: July 24 Poster

Particle detection and velocity prediction for volcanic eruptions : a preliminary study
Maxime Bombrun1 , Vincent Barra1 , Andrew Harris2
1

Clermont-Universite, Universite Blaise Pascal, LIMOS, France, 2 Clermont-Universite, Universite Blaise
Pascal, LMV, France
E-mail: maxime.bombrun@gmail.com

Measuring parameters of all particles as they exit the vent during an explosive eruption is the best way to gather
size, shape, velocity and mass statistics for the solid (particulate) fraction of the plume. We propose to compute
velocities, particle size distributions and mass fluxes using high spatial resolution (cm-to-mm pixel) thermal infrared
imagery collected at 200 Hz for small explosive eruptions at Stromboli (Italy). In order to tackle this problem, wedeveloped a new method based on a pyramidal Lucas and Kanade optical flow algorithm. This allows particles
to be detected, and velocities to be predicted, through time. First, a corner detection algorithm is used to allow
segmentation of the whole image. This procedure of feature identification is based on the motion of the particle.
Then, a differential method is used: the Lucas-Kanade algorithm. This provides a solution of the optical flow
equation. Thus, it enables the computation of the local velocity vector that can be used as an indicator for the
tracking step. Using this method, we were able to obtain both the distribution of particle sizes and velocities. We
examined during one eruption around 650 particles per frame which, for 2637 frames, resulted in around 2152639
particles.

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