decadal persistence of cycles in lava lake motion at erebus volcano antarctica article history studies of erebus volcano s active lava lake have shown that many of its observable properties gas composition surface motion and radiant heat output exhibit cyclic behaviour with a period of 10 min we investigate the multi year progression of the cycles in surface motion of the lake using an extended but intermittent dataset of thermal infrared images collected by the mount erebus volcano observatory between 2004 and 2011 cycles with a period of 5 18 min are found to be a persistent feature of the lake s behaviour and no obvious long term change is observed despite variations in lake level and surface area the times at which gas bubbles arrive at the lake s surface are found to be random with respect to the phase of the motion cycles suggesting that the remarkable behaviour of the lake is governed by magma exchange rather than an intermittent flux of gases from the underlying magma reservoir

pockmark formation and evolution in deep water nigeria rapid hydrate growth versus slow hydrate dissolution in previous works it has been suggested that dissolution of gas hydrate can be responsible for pockmark formation and evolution in deep water nigeria it was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas hydrate dynamics new results obtained by drilling into gas hydrate bearing sediments with the mebo seafloor drill rig in concert with geotechnical in situ measurements and pore water analyses indicate that pockmark formation and evolution in the study area are mainly controlled by rapid hydrate growth opposed to slow hydrate dissolution on one hand positive temperature anomalies free gas trapped in shallow microfractures near the seafloor and coexistence of free gas and gas hydrate indicate rapid hydrate growth on the other hand slow hydrate dissolution is evident by low methane concentrations and almost constant sulfate values 2 m above the gas hydrate occurrence zone

high time resolution fluctuations in volcanic carbon dioxide degassing from mount etna abstract we report here on the first record of carbon dioxide gas emission rates from a volcano captured at 1 hz these data were acquired with a novel technique based on the integration of uv camera observations to measure so2 emission rates and field portable gas analyser readings of plume co2 so2 ratios our measurements were performedat the north east crater of mount etna southern italy and the data reveal strong variability in co2 emissions over timescales of tens to hundreds of seconds spanning two orders of magnitude this carries importantimplications for attempts to constrain global volcanic co2 release to the atmosphere and will lead to an increased insight into short term co2 degassing trends a common oscillation in co2 and so2 emission rates in addition to the co2 so2 ratios was observed at periods of 89 s our results are furthermore suggestive of an intriguing temporal lag between oscillations in co2 emissions and seismicity at periods of 300 400 s with peaks and troughs in the former series leading those in the latter by 150 s this work opens the way to the acquisition of further datasets with this methodology across a range of basaltic systems to better our understandingof deep magmatic processes and of degassing links to manifest geophysical signals

applying the three dimensional model atham to volcanic plumes dynamic of large co ignimbrite eruptions and associated injection heights for volcanic gases 1 many of the past large volcanic eruptions like tambora in 1815 krakatau in 1835 and pinatubo in 1991 were secondary so called co ignimbrite eruptions that were forced over a large area instead of a point source as in the plinian case previous modeling studies were based on one dimensional plume models we used the fully three dimensional plume model atham active tracer high resolution atmospheric model to investigate the dynamics and the resulting plume heights of co ignimbrite eruptions in an idealized setup ash particles as well as a sulfur dioxide so2 tracer are included in the model in the analysis we focus on the behavior of so2 since the neutral buoyancy height is an ill defined parameter for gravitationally settling particles in contrast to plinian plumes the co ignimbrite plumes develop from multiple updrafts resulting in significantly reduced neutral buoyancy heights at least a two dimensional modeling framework is necessary to capture the relevant dynamical features

applying uv cameras for so2 detection to distant or optically thick volcanic plumes abstract ultraviolet uv camera systems represent an exciting new technology for measuring two dimensional sulfur dioxide so 2 distributions in volcanic plumes the high frame rate of the cameras allows the retrieval of so 2 emission rates at time scales of 1 hz or higher thus allowing the investigation of high frequency signals and making integrated and comparative studies with other high data rate volcano monitoring techniques possible one drawback of the technique however is the limited spectral information recorded by the imaging systems here a framework for simulating the sensitivity of uv cameras to various so 2 distributions is introduced both the wavelength dependent transmittance of the optical imaging system and the radiative transfer in the atmosphere are modeled the framework is then applied to study the behavior of different optical setups and used to simulate the response of these instruments to volcanic plumes containing varying so 2 and aerosol abundances located at various distances from the sensor results show that uv radiative transfer in and around distant and or optically thick plumes typically leads to a lower sensitivity to so 2 than expected when assuming a standard beer lambert absorption model furthermore camera response is often non linear in so 2 and dependent on distance to the plume and plume aerosol optical thickness and single scatter albedo the model results are compared with camera measurements made at kilauea volcano hawaii and a method for integrating moderate resolution differential optical absorption spectroscopy data with uv imagery to retrieve improved so 2 column densities is discussed

gas and aerosol emissions from villarrica volcano chile here we report results from a multidisciplinary field campaign at villarrica volcano chile in march 2009 a range of direct sampling and remote sensing techniques was employed to assess gas and aerosol emissions from the volcano and extend the time series of measurements that have been made during recent years airborne traverses beneath the plume with an ultraviolet spectrometer yielded an average so2 flux of 3 7 kg s 1 this value is similar to previous measurements made at villarrica during periods of quiescent activity the composition of the plume was measured at the crater rim using electrochemical sensors and for the first time open path fourier transform infrared spectroscopy yielding a composition of 90 5 mol h2o 5 7 co2 2 6 so2 0 9 hcl 0 3 hf and 0 01 h2s comparison with previous gas measurements made between 2000 and 2004 shows a correlation between increased so2 hcl ratios and periods of increased activity base treated filter packs were also employed during our campaign yielding molar ratios of hbr so2 1 1 10 4 hi so2 1 4 10 5 and hno3 so2 1 1 10 3 in the gas phase our data represent the most comprehensive gas inventory at villarrica to date and the first evaluation of hbr and hi emissions from a south american volcano sun photometry of the plume showed the near source aerosol size distributions were bimodal with maxima at 0 1 and 1 m these findings are consistent with results from analyses in 2003 electron microscope analysis of particulate matter collected on filters showed an abundance of spherical micron sized particles that are rich in si mg and al non spherical s rich particles were also observed

accurately measuring volcanic plume velocity with multiple uv spectrometers a fundamental problem with all ground based remotely sensed measurements of volcanic gas flux is the difficulty in accurately measuring the velocity of the gas plume since a representative wind speed and direction are used as proxies for the actual plume velocity there can be considerable uncertainty in reported gas flux values here we present a method that uses at least two time synchronized simultaneously recording uv spectrometers flyspecs placed a known distance apart by analyzing the time varying structure of so2 concentration signals at each instrument the plume velocity can accurately be determined experiments were conducted on k lauea usa and masaya nicaragua volcanoes in march and august 2003 at plume velocities between 1 and 10 m s 1 concurrent ground based anemometer measurements differed from flyspec measured plume speeds by up to 320 this multi spectrometer method allows for the accurate remote measurement of plume velocity and can therefore greatly improve the precision of volcanic or industrial gas flux measurements

quantification of the gas mass emitted during single explosions on stromboli with the so2 imaging camera we performed measurements using an so2 imaging camera of the so2 gas mass emitted during five discrete explosive events on stromboli volcano on 3 october 2006 the so2 gas mass released during discrete explosions was 15 40 kg per explosion producing 3 8 of the total daily so2 gas emission demonstrating that in terms of gas flux strombolian explosions are a second order phenomenon compared with quiescent degassing using the typical gas composition measured with op ftir allows us to determine the total gas mass released during an explosion as 360 960 kg with a volume of 1500 4100 m 3 at 1 bar at the probable source pressure of gas slug formation of 75 mpa this gas amount would occupy a volume equivalent to a sphere with a radius of 0 8 1 m comparable with estimates of stromboli s conduit geometry c 2009 elsevier b v all rights reserved

volcanic particle aggregation in explosive eruption columns part ii numerical experiments abstract the goal of this paper is to determine the parameters that control the aggregation efficiency and the growth rate of volcanic particles within the eruption column numerical experiments are performed with the plume model atham active tracer high resolution atmospheric model in this study we employ the parameterizations described in a companion paper this issue the presence of hydrometeors promotes the aggregation of ash particles which strongly increases their fall velocities and thus their environmental impact the tephra mass is about two orders of magnitude greater than that of hydrometeors during typical plinian eruptions without interaction of external water ice is highly dominant in comparison to liquid water 99 by mass this is caused by the fast column rise 100 m s 1 on average to very cold altitudes most particles occur in the form of frozen aggregates with low ice content the collection efficiency is governed by the availability of hydrometeors acting as adhesives at the particles surface in our study and wet ash particles have a higher sticking capacity than icy ones therefore aggregation is fastest during the eruption within the column when limited regions of liquid water exist and when particle concentrations are very high of the order of 10 5 cm 3 increased humidity in the background atmosphere generally leads to enhanced ice formation but shows only a weak influence on the aggregation process first sensitivity studies showed however a significant increase of the liquid water fraction when considering salinity effects the availability of water or ice at the particles surfaces is also governed by the surface properties the porosity and permeability of ash which are not well established to date particle growth is significantly enhanced for greater differences in the sizes and fall velocities among particles as gravitational capture becomes more efficient our experiments indicate a major influence of the erupted particle size distribution first sensitivity studies show that electrostatic forces result in a significant enhancement of aggregated particles the present exploratory study provides new insights into the sensitivity of the ash aggregation process to a number of key parameters our results indicate the need of further constraining particle composition size porosity permeability and surface properties at low temperatures by in situ observations in the laboratory and in the field in addition further research on electrostatic aggregation would be desirable

use of motion estimation algorithms for improved flux measurements using so 2 cameras abstract article history received 3 april 2014accepted 18 august 2014available online xxxxkeywords so 2 uxso 2 cameraplume speedplume modellingoptical owmotion estimation so 2 cameras are rapidly gaining popularity as a tool for monitoring so 2 emissions from volcanoes severaldifferent so 2 camera systems have been developed with varying patterns of image acquisition in space timeand wavelength despite this diversity there are two steps common to the work owsofmostofthesesystems aligning images of different wavelengths to calculate apparent absorbance and estimating plume transportspeeds both of which can be achieved using motion estimation algorithms here we present two suchalgorithms adualtreecomplexwavelettransform basedalgorithmandthefarnebackopticalflowalgorithm weassesstheiraccuracyusingasyntheticdatasetcreatedusingthenumericcloud resolvingmodelatham andthen apply them to real world data from villarrica volcano both algorithms are found to perform well and theatham simulations offer useful datasets for benchmarking and validating future algorithms 2014 the authors published by elsevier b v this is an open access article under the cc by license http creativecommons org licenses by 3 0

uv camera measurements of fumarole field degassing la fossa crater vulcano island abstract the uv camera is becoming an important new tool in the armory of volcano geochemists to derive high time resolution so2 flux measurements furthermore the high camera spatial resolution is particularly useful for exploring multiple source so2 gas emissions for instance the composite fumarolic systems topping most quiescent volcanoes here we report on the first so2 flux measurements from individual fumaroles of the fumarolic field of la fossa crater vulcano island aeolian island which we performed using a uv camera in two field campaigns in november 12 2009 and february 4 2010 we derived 0 5 hz so2 flux time series finding fluxes from individual fumaroles ranging from 2 to 8 7 t d 1 with a total emission from the entire system of 20 t d 1 and 13 t d 1 in november 2009 and february 2010 respectively these data were augmented with molar h2s so2 co2 so2 and h2o so2 ratios measured using a portable multigas analyzer for the individual fumaroles using the so2 flux data in tandem with the molar ratios we calculated the flux of volcanic species from individual fumaroles and the crater as a whole co2 684 t d 1 and 293 t d 1 h2s 8 t d 1 and 7 5 t d 1 and h2o 580 t d 1 and 225 t d 1

the so2 camera a simple fast and cheap method for ground based imaging of so2 in volcanic plumes 1 so2 flux is widely monitored on active volcanoes as it gives a window into the hidden subsurface magma dynamics we present here a new approach to so2 flux monitoring using ultraviolet imaging of the volcanic plume through carefully chosen filters to produce images of so2 column amount the so2 camera heralds a breakthrough in both our ability to measure so2 flux at unprecedented frequencies 2 hz and at unprecedented accuracy thanks to the application of correlation techniques to determine wind speed directly from the images and the ability to measure the whole profile simultaneously in this paper we detail the commercially available pieces required to construct the so2 camera introduce a retrieval scheme to determine so2 amounts from the images and present results from a field campaign in november 2005 on sakurajima volcano japan

ascent dynamics of large phreatomagmatic eruption clouds the role of microphysics 1 we examine the impact of abundant surface water interaction on the development of volcanic clouds from large scale 108 kg s 1 magma phreatomagmatic eruptions presenting the first 2 d large eddy simulations of wet volcanic plumes that incorporate the effects of microphysics the active tracer high resolution atmospheric model was forced with field derived inputs from an exceptionally large phreatomagmatic eruption the 27 ka oruanui supereruption taupo volcano new zealand surface water contents were varied from 0 to 40 wt for eruptions with equivalent magma eruption rates of 1 3 108 and 1 1 109 kg s 1 our findings confirm that increased surface water has a pronounced impact on column stability leading to transitional column behavior and hybrid clouds resulting from simultaneous ascent of material from stable columns and pyroclastic density currents pdcs contrary to the suggestion of previous workers however abundant surface water does not systematically lower the spreading level or maximum height of volcanic clouds owing to vigorous microphysics assisted lofting of pdcs the simulated behavior and ash cloud dimensions provide a close match to field evidence from the oruanui case study cloud heights from the collapsing eruption columns also show a notable sensitivity to changes in the altitude of the tropopause while ambient humidity primarily impacts the abundance of airborne hydrometeors particularly ice associated with the volcanic clouds general relationships between eruption style meteorological conditions and the resulting vertical profiles of volcanic emissions outlined here could also be adapted for use in operational volcanic ash forecasting and deposit reconstruction techniques already in existence

accurate measurement of volcanic so2 flux determination of plume transport speed and integrated so2 concentration with a single device 1 ground based measurements of volcanic sulfur dioxide fluxes are important indicators of volcanic activity with application in hazard assessment and understanding the impacts of volcanic emissions upon the environment and climate these data are obtained by making traverses underneath the volcanic plume a few kilometers from source with an ultraviolet spectrometer measuring integrated so2 concentrations across the plume s cross section and multiplying by the plume s transport speed however plume velocities are usually derived from ground based anemometers located many kilometers from the traverse route and hundreds of meters below plume altitude complicating the experimental design and introducing large flux can be 100 errors here we present the first report of a single instrument capable of accurate volcanic so2 flux measurements this device records integrated so2 concentrations and plume heights during traverses between traverses two in plume so2 time series are measured from underneath the plume with the instrument corresponding to zenith and inclined user specified angle from vertical in the direction of the volcano fields of view respectively the distance between the points of intersection of the two views with the plume is found on the basis of the determined plume height and the two signals are cross correlated to determine the lag between them enabling accurate derivation of the wind speed we present flux data with errors 12 obtained in this way at mt etna during july 2004

space and ground based measurements of sulphur dioxide emissions from turrialba volcano costa rica remotely sensed measurements of sulphur dioxide so2 emitted by turrialba volcano costa rica are reported for the period september 2009 january 2011 these measurements were obtained using images from advanced spaceborne thermal emission and reflexion radiometer ozone monitoring instrument and a ground based uv camera these three very different instruments provide flux measurements in good agreement with each other which demonstrate that they can be integrated for monitoring so2 fluxes fluxes from turrialba increased fourfold in january 2010 following a phreatic explosion that formed a degassing vent in the w crater of turrialba since then the so2 flux has remained high 30 50 kg s but seems to be showing a slowly decreasing trend we interpret this evolution as the start of open vent degassing from a recently intruded magma body the opening of the degassing vent decreased the confining pressure of the magma body and allowed the gases to bypass the hydrothermal system

protocols for uv camera volcanic so2 measurements abstract ultraviolet camera technology offers considerable promise for enabling 1 hz timescale acquisitions of volcanic degassing phenomena providing two orders of magnitude improvements on sampling frequencies from conventionally applied scanning spectrometer systems this could for instance enable unprecedented insights into rapid processes such as strombolian explosions and non aliased corroboration with volcano geophysical data the uptake of this technology has involved disparate methodological approaches hitherto as a means of expediting the further proliferation of such systems we here study these diverse protocols with the aim of suggesting those we consider optimal in particular we cover choice and set up of hardware calibration for vignetting and for absolute concentrations using quartz so 2 cells the retrieval algorithm and whether one or two filters or indeed cameras are necessary this work also involves direct intercomparisons with narrowband observations obtained with a scanning spectrometer system employing a differential optical absorption spectroscopic evaluation routine as a means of methodological validation

volcanic particle aggregation in explosive eruption columns part i parameterization of the microphysics of hydrometeors and ash abstract the aggregation of volcanic ash particles within the eruption column of explosive eruptions has been observed at many volcanoes it influences the residence time of ash in the atmosphere and the radiative properties of the umbrella cloud however the information on the processes leading to aggregate formation are still either lacking or very incomplete we examine the fate of ash particles through numerical experiments with the plume model atham active tracer high resolution atmospheric model in order to determine the conditions that promote ash particle aggregation in this paper we describe the microphysics and parameterization of ash and hydrometeors in a companion paper this issue we use this information in a series of numerical experiments the parameterization includes the condensation of water vapor in the rising eruption column the formation of liquid and solid hydrometeors and the effect of latent heat release on the eruption column dynamics are considered the interactions of hydrometeors and volcanic ash within the eruption column that lead to aggregate formation are simulated for the first time within a rising eruption column the microphysical parameterization follows a modal approach the hydrometeors are described by two size classes each of which is divided into a liquid and a frozen category by analogy with the hydrometeor classification we specify four categories of volcanic ash particles we imply that volcanic particles are active as condensation nuclei for water and ice formation ash can be contained in all categories of hydrometeors thus forming mixed particles of any composition reaching from mud rain to accretionary lapilli collisions are caused by gravitational capture of particles with different fall velocity coalescence of hydrometeor ash aggregates is assumed to be a function of the hydrometeor mass fraction within the mixed particles the parameterization also includes simplified descriptions of electrostatics and salinity effects

image based measurement of flux variation in distal regions of active lava flows 1 understanding the processes involved with the advance of lava flows is critical for improving hazard assessments at many volcanoes here we describe the application of computer vision and oblique photogrammetric techniques to visible and thermal images of active a flows in order to investigate distal flow processes at mount etna sicily photogrammetric surveys were carried out to produce repeated topographic data sets for calculation of volumetric lava flux at the flow fronts velocity profiles from a distal channel were obtained by rectification of a thermal image sequence and are used to investigate the rheological properties of the lava significant variations of the magma flux were observed and pulses of increased flux arrived within the flow front region on timescales of several hours the pulses are believed to be the distal result of more frequent flux changes observed in the vent region hence they reflect the importance of flow processes which are believed to cause the coalescence of flux pulses along the channel system as well as short period variations in effusion rate in considering advance processes for the individual flow fronts it must be assumed that they were fed by a highly unsteady flux which was volumetrically at least an order of magnitude lower than that observed near the vent

nitric acid from volcanoes abstract atmospheric cycling of nitric acid and other nitrogen bearing compounds is an important biogeochemical process with significant implications for ecosystems and human health volcanoes are rarely considered as part of the global nitrogen cycle but here we show that they release a previously unconsidered flux of hno3 vapour to the atmosphere we report the first measurements of nitric acid vapour in the persistent plumes from four volcanoes masaya nicaragua etna italy and villarrica and lascar chile mean near source volcanic plume concentrations of hno3 range from 1 8 to 5 6 mol m 3 an enrichment of one to two orders of magnitude over background 0 1 1 5 mol m 3 using mean molar hno3 so2 ratios of 0 01 0 02 0 05 and 0 07 for villarrica masaya etna and lascar respectively combined with so2 flux measurements we calculate gaseous hno3 fluxes from each of these volcanic systems and extend this to estimate the global flux from high temperature non explosive volcanism to be 0 02 0 06 tg n yr 1 while comparatively small on the global scale this flux could have important implications for regional fixed n budgets the precise mechanism for the emission of this hno3 remains unclear but we suggest that thermal nitrogen fixation followed by rapid oxidation of the product no is most likely in explosive ash rich plumes no may result from or at least be supplemented by production from volcanic lightning rather than thermal n fixation we have calculated no production via this route to be of the order of 0 02 tg n yr 1