a detailed 2840 year record of explosive volcanism in a shallow ice core from dome a east antarctica a detailed history of volcanism covering the last 2840 years is reconstructed from the top 100 42 m of a 109 91 m ice core from dome a da2005 ice core east antarctica using two known volcanic stratigraphic markers the mean accumulation rate during the period ad 1260 1964 is found to be 23 2 mm w e a 1 consistent with the previously reported accumulation rate at dome a this mean accumulation rate is used to date the entire core volcanic eruptions in the period 840 bc ad 1998 are detected as outstanding sulphate events seventy eight eruptions are identified with a mean of 2 7 eruptions per century comparisons with previous antarctic ice core volcanic records are made to assess the quality of this new da2005 record in terms of dates for volcanic events the da2005 record is in good agreement with previous records in the second millennium ad ad 1000 1998 a series of volcanic signatures found in both the da2005 record and several other antarctic ice core records in the first millennium ad ad 1 1000 appear to validate the da2005 record during this time period for the older periods direct comparisons are difficult between the da2005 record and other antarctic ice core records due to the lack of well dated stratigraphic horizons

distribution of soluble impurities in cold glacial ice understanding the microstructure of ice underpins the interpretation of ice core measurements and many ice sheet properties a detailed study of polar snow and ice using scanning electron microscope sem and x ray analysis revealed the microstructural distribution of soluble impurities sublimation under vacuum etching concentrated impurity from both the bulk and grain boundaries on to the specimen surfaces in detectable quantities sublimation in the cold room before examination preetching collected previously unobservable quantities of impurity at triple junctions a heterogeneous distribution of impurities was observed chloride was frequently found to originate from the lattice but not usually at triple junctions other impurities particularly sodium chloride were detected at grain boundaries and bubble surfaces sulphate was often found at triple junctions in specimens containing a high bulk concentration of the acid frequently in conjunction with cations this suggests the possibility that veins were only filled with significant amounts of impurity when the surrounding grain boundaries were saturated the model of impurity arrangement inferred from the results reconciles differences between previous sem studies additionally it is consistent with and explains recent electrical conduction observations the disconnected arrangement of impurity filled grain boundaries and veins limits opportunities for significant post depositional solute movement

exploring the explosive effusive transition using permanent ultra violet cameras understanding the mechanisms that cause effusive eruptions is the key to mitigating their associated hazard here we combine results from permanent ultra violet uv cameras and from other geophysical observations seismic very long period thermal and infrasonic activity to characterize volcanic so2 flux regime in the period prior during and after stromboli s august november 2014 effusive eruption we show that in the two months prior to effusion onset the so2 flux levels are two times average level we explain this anomalously high so2 regime as primarily determined by venting of rapidly rising pressurized so2 rich gas pockets produced by strombolian explosions being more frequent and intense than usual we develop a procedure to track and count in the uv camera record the so2 flux pulses produced by individual explosions and puffing activity active degassing we find that these so2 pulses are far more numerous 67 47 events hour before the effusion onset than during normal activity 20 15 events hour this observation combined with geophysical evidence demonstrates an elevated gas bubble supply to the shallow conduits causing elevated explosive and puffing activity this increase 0 1 m3s 1 in magma transport rate in the north east feeding conduits finally triggers effusion onset active degassing remains elevated also during the effusive phase supporting the persistence of explosive and puffing activity during the effusive eruption deep in the volcanic conduit our results demonstrate that permanent uv cameras can valuably contribute to monitoring at high sampling frequency gas dynamics and fluxes thus opening the way to direct comparison with more established geophysical observations

an automated so 2 camera system for continuous real time monitoring of gas emissions from kīlauea volcano s summit overlook crater abstract so 2 camera systems allow rapid two dimensional imaging of sulfur dioxide so 2 emitted from volcanic vents here we describe the development of an so 2 camera system specifically designed for semi permanent field installation and continuous use the integration of innovative but largely off the shelf components allowed us to assemble a robust and highly customizable instrument capable of continuous long term deployment at k lauea volcano s summit overlook crater recorded imagery is telemetered to the usgs hawaiian volcano observatory hvo where a novel automatic retrieval algorithm derives so 2 column densities and emission rates in real time imagery and corresponding emission rates displayed in the hvo operations center and on the internal observatory website provide hvo staff with useful information for assessing the volcano s current activity the ever growing archive of continuous imagery and high resolution emission rates in combination with continuous data from other monitoring techniques provides insight into shallow volcanic processes occurring at the overlook crater an exemplary dataset from september 2013 is discussed in which a variation in the efficiency of shallow circulation and convection the processes that transport volatile rich magma to the surface of the summit lava lake appears to have caused two distinctly different phases of lake activity and degassing this first successful deployment of an so 2 camera for continuous real time volcano monitoring shows how this versatile technique might soon be adapted and applied to monitor so 2 degassing at other volcanoes around the world

attenuation measurements from sonic waveform logs in methane hydrate bearing sediments at the nankai trough exploratory well off tokai central japan 1 i have used full waveform logs from the nankai trough exploratory well off central japan to estimate both compressional and shear attenuation in sediments containing methane hydrate mh the attenuation estimates are based on a median frequency shift to the amplitude spectrum of the recorded waveforms this paper is concerned with attenuation at sonic frequencies of 10 20 khz for compressional waves and 500 1000 hz for shear waves i observed that the presence of mh increases the host sediments seismic attenuation and shear attenuation may be more helpful than compressional attenuation in detecting or characterizing mh bearing sediments as compressional attenuation is affected by the presence of gas moreover the ratio of compressional to shear attenuation is found to be a more sensitive indicator of the presence of low saturation gas than the corresponding velocity ratio

periodic volcanic degassing behavior the mount etna example 1 in contrast to the seismic and infrasonic energy released from quiescent and erupting volcanoes which have long been known to manifest episodes of highly periodic behavior the spectral properties of volcanic gas flux time series remain poorly constrained due to a previous lack of hightemporal resolution gas sensing techniques here we report on so2 flux measurements performed on mount etna with a novel uv imaging technique of unprecedented sampling frequency 0 5hz which reveal for the first time a rapid periodic structure in degassing from this target these gas flux modulations have considerable temporal variability in their characteristics and involve two period bands 40 250 and 500 1200s a notable correlation between gas flux fluctuations in the latter band and contemporaneous seismic root mean square values suggests that this degassing behavior may be generated by periodic bursting of rising gas bubble trains at the magma air interface citation tamburello g a aiuppa a j s mcgonigle p allard a cannata g giudice e p kantzas and t d pering 2013 periodic volcanic degassing behavior the mount etna example geophys res lett 40 4818 4822 doi 10 1002 grl 50924

impurity sources of f cl no3 and so4 2 in greenland and antarctic precipitation five polar impurity sources are proposed anthropogenic no3 and so42 in recent greenland but not antarctic snow marine aerosols the dominant cl source volcanic eruptions which produce detectable but variable peaks in so42 f and or cl concentrations biogenic sulfurous gases from soil and coastal waters the dominant source for so42 in nonvolcanic strata an unidentified source of background nitrate which is more active in the northern hemisphere and which displays a summer concentration maximum solar activity and supernova events do not modulate no3 concentrations in greenland snow

long term changes in the acid and salt concentrations of the greenland ice core project ice core from electrical stratigraphy continuous electrical records covering a climatic cycle are presented for the greenland ice core project deep ice core from greenland electrical conductivity measurement ecm measures the acid content of the ice and the dielectric profile dep responds to acid ammonium and chloride all features seen can be explained by chemical changes in the ice and there is no evidence so far for any major change in electrical response with depth or age of the ice both records are dominated by the acidity of the ice which varies strongly from acidic in warm periods to alkaline in cold periods controlled by neutralization by alkaline dust calcareous and other mineral dust when ca is low the acidity mainly nitric acid has a fairly constant background level throughout the cycle with slightly lower values in ice believed to be from the last interglacial ca has to rise only slightly to neutralize the available acidity so that acidity is a highly nonlinear reflection of climate changes if neutralization occurred in the aerosol rather than in the ice then the number of cloud condensation nuclei over parts of the northern hemisphere could have been reduced leading to reduced cloud albedo this nonlinear feedback may have some importance for modeling of climate change when both acid and ammonium levels are low the dep signal can be used to give a rapid indication of chloride trends

a 220 year continuous record of volcanic h2so4 in the antarctic ice sheet continuous h2so4 profiles observed in snow from several antarctic locations reveal four major volcanic events of the past two centuries agung krakatoa tambora and another large scale event not recorded historically acid deposition and interhemispheric distribution mechanisms are quantified and then used to obtain an order of magnitude estimate for the h2so4 emissions from these eruptions

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

holocene volcanic history as recorded in the sulfate stratigraphy of the european project for ice coring in antarctica dome c edc96 ice core 1 a detailed history of holocene volcanism was reconstructed using the sulfate record of the european project for ice coring in antarctica dome c edc96 ice core this first complete holocene volcanic record from an antarctic core provides a reliable database to compare with long records from antarctic and greenland ice cores a threshold method based on statistical treatment of the lognormal sulfate flux distribution was used to differentiate volcanic sulfate spikes from sulfate background concentrations ninety six eruptions were identified in the edc96 ice core during the holocene with a mean of 7 9 events per millennium the frequency distribution events per millennium showed that the last 2000 years were a period of enhanced volcanic activity edc96 volcanic signatures for the last millennium are in good agreement with those recorded in other antarctic ice cores for older periods comparison is in some cases less reliable mainly because of dating uncertainties sulfate depositional fluxes of individual volcanic events vary greatly among the different cores a volcanic flux normalization volcanic flux tambora flux ratio was used to evaluate the relative intensity of the same event recorded at different sites in the last millennium normalized flux variability for the same event showed the highest value in the 1100 1500 ad period this pattern could mirror changes in regional transport linked to climatic variations such as slight warming stages in the southern hemisphere southern hemisphere medieval warming like period

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

real time measurement of volcanic so 2 emissions validation of a new uv correlation spectrometer flyspec a miniaturized lightweight and low cost uv correlation spectrometer the flyspec has been devel oped as an alternative for the cospec which has long been the mainstay for monitoring volcanic sulfur dioxide fluxes field experiments have been conducted with the flyspec at diverse volcanic systems including masaya nicaragua po as costa rica stromboli etna and vulcano italy villarica chile and kilauea usa we present here those validation measurements that were made simultaneously with cospec at kilauea between march 2002 and february 2003 these experiments with source emission rates that ranged from 95 to 1 560 t d 1 showed statistically identical results from both instruments so2 path concentrations ranged from 0 to 1 000 ppm m with average correlation coefficients greater than r 2 0 946 the small size and low cost create the opportunity for flyspec to be used in novel deployment modes that have the potential to revolutionize the manner in which volcanic and industrial monitoring is performed

spatial and temporal variability of snow accumulation in east antarctica from traverse data recent snow accumulation rate is a key quantity for ice core and mass balance studies several accumulation measurement methods stake farm fin core snow radar profiling surface morphology remote sensing were used compared and integrated at eight sites along a transect from terra nova bay to dome c east antarctica to provide information about the spatial and temporal variability of snow accumulation thirty nine cores were dated by identifying tritium b marker levels 1965 66 and non sea salt nss so4 2 spikes of the tambora indonesia volcanic event 1816 in order to provide information on temporal variability cores were linked by snow radar and global positioning system surveys to provide detailed information on spatial variability in snow accumulation stake farm and ice core accumulation rates are observed to differ significantly but isochrones snow radar correlate well with ice core derived accumulation the accumulation ablation pattern from stake measurements suggests that the annual local noise metre scale in snow accumulation can approach 2 years of ablation and more than four times the average annual accumulation with no accumulation or ablation for a 5 year period in up to 40 of cases the spatial variability of snow accumulation at the kilometre scale is one order of magnitude higher than temporal variability at the multi decadal secular scale stake measurements and firn cores at dome c confirm an approximate 30 increase in accumulation over the last two centuries with respect to the average over the last 5000 years

snow megadunes in antarctica sedimentary structure and genesis 1 megadune fields occupy large areas in the interior of the east antarctic ice sheet and are the result of unusual snow accumulation and redistribution processes they therefore are important to surface mass balance and ice core interpretation field observations gps gpr and surface measurements have provided a detailed description of megadune sedimentation and morphology over a 70 km2 area located 200 km east of dome c a combination of remote sensing analysis using landsat and satellite radar altimetry and field measurements indicate that slope in the prevailing wind direction spwd and climatic conditions play a crucial role in megadune genesis the megadune areas tend to be characterized by slightly steeper regional slope and the presence of highly persistent katabatic winds the megadunes represent 2 to 4 m amplitude waves of 2 to 5 km wavelength formed by variable net accumulation ranging between 25 leeward faces to 120 windward faces of the accumulation in adjacent nonmegadune areas leeward faces are characterized by glazed sastrugi free surfaces and extensive depth hoar formation windward faces are covered by large rough sastrugi up to 1 5 m in height

ifit a simple method for measuring volcanic so2 without a measured fraunhofer reference spectrum abstract accurate quantification of the emission rate of sulphur dioxide so2 from volcanoes provides both insights into magmatic processes and a powerful monitoring tool for hazard mitigation the primary method for measuring magmatic so2 is differential optical absorption spectroscopy doas of uv scattered sunlight spectra in which a reference spectrum taken outside the plume is used to quantify the so2 slant column density inside the plume this can lead to problems if the reference spectrum is contaminated with so2 as this will result in a systematic underestimation of the retrieved so2 slant column density and therefore emission rate we present a new analysis method named ifit which retrieves the so2 slant column density from uv spectra by directly fitting the measured intensity spectrum at high spectral resolution 0 01 nm using a literature solar reference spectrum and measured instrument characteristics this eliminates the requirement for a measured reference spectrum providing a point and shoot method for quantifying so2 slant column densities we show that ifit retrieves correct so2 slant column densities in a series of test cases finding agreement with existing methods we propose that ifit is suitable for both traverse measurements and permanent scanning stations and could be integrated into volcano monitoring networks at observatories finally we provide an open source software implementation of ifit with a user friendly graphical interface to allow users to easily utilise ifit

lead ba and bi in antarctic law dome ice corresponding to the 1815 ad tambora eruption an assessment of emission sources using pb isotopes lead ba and bi concentrations and pb isotopic compositions have been measured in antarctic law dome 66 8 s 112 4 e ice dated from 1814 ad to 1819 ad by thermal ionisation mass spectrometry to investigate the possible deposition of heavy metals from the 1815 ad eruption of tambora volcano 8 5 s 117 4 e in indonesia although volcanic s emissions from tambora observed as so42 are present in the antarctic ice core record there are grounds to question the origin of the pb and bi also deposited at law dome from late 1817 as the pb isotope data suggest this pb originated from mount erebus 77 5 s 167 2 e on ross island antarctica it is shown that at least 97 of any pb and bi emitted from tambora was removed from the atmosphere within the 1 6 year period required to transport aerosols from indonesia to antarctica consequently increased pb and bi concentrations observed in law dome ice about 1818 ad are attributed to either increased heavy metal emissions from mount erebus or increased fluxes of heavy metals to the antarctic ice sheet resulting from climate and meteorological modifications following the tambora eruption elevated ba concentrations observed from mid 1816 to mid 1818 indicate increased atmospheric loading of rock and soil dust also occurred at the time

using so 2 camera imagery and seismicity to examine degassing and gas accumulation at kīlauea volcano may 2010 abstract so 2 camera measurements at k lauea volcano hawaii in may of 2010 captured two occurrences of lava lake rise and fall within the halema um au crater summit vent during high lava stands we observed diminished so 2 emission rates and decreased seismic tremor similar events at k lauea have been described as the result of sporadic degassing following gas accumulation beneath a mostly impermeable lava lake surface incorporation of so 2 camera data into a multi parameter dataset gives credence to the likelihood of shallow gas accumulation as the cause of these high stand events with accumulated gas release upon lake level drop compensating for the gas deficit reached during accumulation

comparison of holocene electrical records from dome c and vostok antarctica as part of the european project for ice coring in antarctica a new deep ice core is being drilled at dome c two electrical methods have been used on the core drilled so far a new design of electrical conductivity method ecm instrument and a traditional dielectric profiler the two profiles are very similar in both peaks and background consistent with acidity being the dominant influence on both in this part of the record the dome c records have been compared to ecm records from vostok and a tentative match has been made between them this suggests a long term average ratio of accumulation rate of 1 36 between this dome c core and vostok and that the dome c core analyzed so far to 358 m probably includes the very end of the glacial holocene transition

volcanological applications of so2 cameras ground based volcanic gas and ash imaging has the potential to revolutionise the way in which volcanoes are monitored and studied the ability to track and quantify volcanic emissions in space and time with unprecedented fidelity opens the door to integration with geophysical measurements allowing breakthroughs in our understanding of the physical processes driving volcanic activity in may 2013 a european science foundation funded plume imaging workshop was conducted in strombolutaly with the objective of bringing the ground based volcanic plume imaging community together in order to examine the state of the art and move towards a best practice for volcanic ash and gas imaging techniques a particular focus was the development of so2 imaging systems or so2 cameras with six teams deploying and testing various designs of ultraviolet and infrared based imaging systems capable of imagining so2 one conclusion of the workshop was that the term so2 camera should be applied to any so2 imaging system regardless of wavelength of radiation used this special issue on volcanic plume imaging is the direct result of the stromboli workshop and together the papers presented here represent the state of the art of ground based volcano plume imaging science and technology in this work we examine in detail the volcanological applications of the so2 camera reviewing previous works and placing the new research contained in this special issue in context the development of the so2 camera and future developments extending imaging to other volcanic gases is one of the most exciting and novel research frontiers in volcanology today c 2014 published by elsevier b v

shallow and deep controls on lava lake surface motion at kīlauea volcano abstract lava lakes provide a rare window into magmatic behavior and lake surface motion has been used to infer deeper properties of the magmatic system at halema uma u crater at the summit of k lauea volcano multidisciplinary observations for the past several years indicate that lava lake surface motion can be broadly divided into two regimes 1 stable and 2 unstable stable behavior is driven by lava upwelling from deeper in the lake presumably directly from the conduit and is an intrinsic process that drives lava lake surface motion most of the time this stable behavior can be interrupted by periods of unstable flow often reversals driven by spattering a shallowly rooted process often extrinsically triggered by small rockfalls from the crater wall the bursting bubbles at spatter sources create void spaces and a localized surface depression which draws and consumes surrounding surface crust spattering is therefore a location of lava downwelling not upwelling stable i e deep upwelling driven and unstable i e shallow spattering driven behavior often alternate through time have characteristic surface velocities flow directions and surface temperature regimes and also correspond to changes in spattering intensity outgassing rates lava level and seismic tremor these results highlight that several processes originating at different depths can control the motion of the lava lake surface and long term interdisciplinary monitoring is required to separate these influences these observations indicate that lake surface motion is not always a reliable proxy for deeper lake or magmatic processes from these observations we suggest that shallow outgassing spattering not lake convection drives the variations in lake motion reported at erta ale lava lake

firn air δ15n in modern polar sites and glacial interglacial ice a model data mismatch during glacial periods in antarctica the phase lag between atmospheric composition air bubbles and temperature water isotopes can be quantified from ice cores provided that the age difference between entrapped air and the surrounding air can be correctly estimated this difference depends on the lock in depth lid when air no longer mixes with the atmosphere the lid can be estimated from firnification models or from the air isotopic composition 15n and 40ar both methods give consistent results for greenland and one coastal site in antarctica byrd new firn measurements in greenland northgrip and antarctica berkner island bas depot dome c confirm that firnification models correctly reproduce the present lid over a large range of surface conditions however a systematic mismatch is observed for the last glacial maximum lgm in east antarctic sites vostok dome c dome f questioning the model s validity here we use new 15n measurements from two coastal antarctic sites kohnen station and law dome providing depth estimates again distinct from firnification model calculations we show that this discrepancy can be resolved by revising the estimate of past accumulation rates 15n measurements can therefore help to constrain past accumulation rate and improve ice core dating

a global synthesis of lava lake dynamics abstract active lava lakes represent a variety of open vent volcanism in which a sizable body of lava accumulates at the top of the magma column constrained by the vent and or crater geometry the longevity of lava lakes reflects a balancing of cooling and outgassing occurring at the surface and input of hot and gas rich magma from below due to their longevity and relative accessibility lava lakes provide a natural laboratory for studying fundamental volcanic processes such as degassing convection and cooling this article examines all seven lakes that existed at the time of writing in 2018 located in the pacific antarctica africa and south and central america these lakes span all tectonic environments and a range of magma compositions we focus on analysis of the lake surface motion using image velocimetry which reveals both similarities and contrasts in outgassing and lake dynamics when comparing the different lakes we identify two categories of lake behavior organized erta ale nyiragongo k lauea after 2011 and erebus and chaotic villarrica masaya marum this division does not map directly to lake size viscosity gas emission rate or temperature instead when examined together we find that the lakes follow a linear relationship between average surface speed and the ratio of total gas flux to lake surface area this relationship points to the combined importance of both flux and lake size in addition to the total volume of gas emission and suggests that a shared deep mechanism controls the supply of heat and gas to all lakes on the other hand the differences between chaotic and organized lakes highlight the important role of the geometry of the conduit lake transition which superimposes a shallow signal on that of the deep circulation the spatial patterns of surface motion we document suggest that the release of gas bubbles at chaotic lakes is more efficient i e bubbles are less likely to be retained and recycled compared with organized lakes in addition the data presented here indicate that the solidified crust of organized lakes plays a role in regulating convection and outgassing in lava lakes

limited dechlorination of sea salt aerosols during the last glacial period evidence from the european project for ice coring in antarctica epica dome c ice core 1 chloride cl and sodium na in ice cores originate mainly from sea salt and one would thus expect the cl na ratio to reflect the seawater ratio however at dome c a low accumulation site in east antarctica this is not the case in present day snow instead a cl excess relative to na is observed in surface snow and within a few meters depth the cl concentration decreases and the cl na ratio becomes significantly lower than the seawater ratio aerosol studies at coastal antarctic sites have shown that the reaction of sea salt aerosols with nitric and sulphuric acid leads to the formation of hcl that eventually escapes the sea salt aerosol the observed decrease in cl concentrations in the uppermost snow layers is due to reemission of hcl from the snow postdepositional loss of hcl depends among other factors on the accumulation rate at the site with lower accumulation rates leading to larger losses during the last glacial maximum lgm the cl na ratio is relatively stable and close to the seawater ratio despite the even lower accumulation rate during that time the likely explanation for this conflicting observation is that high levels of dust neutralized nitric and sulphuric acids during the lgm which in turn reduced the formation of hcl from sea salt aerosol with less or no hcl formed postdepositional loss would be prevented keeping the cl na ratio close to that of sea water

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

sun photometer and lidar measurements of the plume from the hawaii kilauea volcano pu u o o vent aerosol flux and so2 lifetime 1 aerosol optical depths and lidar measurements were obtained under the plume of hawaii kilauea volcano on august 17 2001 9 km downwind from the erupting pu u o o vent measured aerosol optical depths at 500 nm were between 0 2 0 4 aerosol size distributions inverted from the spectral sun photometer measurements suggest the volcanic aerosol is present in the accumulation mode 0 1 0 5 micron diameter which is consistent with past in situ optical counter measurements the aerosol dry mass flux rate was calculated to be 53 mg d 1 the estimated so2 emission rate during the aerosol measurements was 1450 mg d 1 assuming the sulfur emissions at pu u o o vent are mainly so2 not aerosol this corresponds to a so2 half life of 6 0 hours in the atmosphere

intercomparison of so2 camera systems for imaging volcanic gas plumes abstract so 2 camera systems are increasingly being used to image volcanic gas plumes the ability to derive so 2 emission rates directly from the acquired imagery at high time resolution allows volcanic process studies that incorporate other high time resolution datasets though the general principles behind the so 2 camera have remained the same for a number of years recent advances in ccd technology and an improved understanding of the physics behind the measurements have driven a continuous evolution of the camera systems here we present an intercomparison of seven different so 2 cameras in the first part of the experiment the various technical designs are compared and the advantages and drawbacks of individual design options are considered though the ideal design was found to be dependent on the specific application a number of general recommendations are made next a time series of images recorded by all instruments at stromboli volcano italy is compared all instruments were easily able to capture so 2 clouds emitted from the summit vents quantitative comparison of the so 2 load in an individual cloud yielded an intra instrument precision of about 12 from the imagery emission rates were then derived according to each group s standard retrieval process a daily average so 2 emission rate of 61 10 t d was calculated due to differences in spatial integration methods and plume velocity determination the time dependent progression of so 2 emissions varied significantly among the individual systems however integration over distinct degassing events yielded comparable so 2 masses based on the intercomparison data we find an approximate 1 sigma precision of 20 for the emission rates derived from the various so 2 cameras though it may still be improved in the future this is currently within the typical accuracy of the measurement and is considered sufficient for most applications

a tentative chronology for the epica dome concordia ice core a tentative age scale edc1 for the last 45 kyr is established for the new 788 m epica dome c ice core using a simple ice flow model the age of volcanic eruptions the end of the younger dryas event and the estimated depth and age of elevated 10be about 41 kyr ago were used to calibrate the model parameters the uncertainty of edc1 is estimated to 10 yr for 0 to 700 yr bp up to 200 yr back to 10 kyr bp and up to 2 kyr back to 41 kyr bp the age of the air in the bubbles is calculated with a firn densification model in the holocene the air is about 2000 yr younger than the ice and about 5500 yr during the last glacial maximum

a review of controls on lava lake level insights from halema uma u crater kīlauea volcano the height of the lava column is a fundamental measure of open vent volcanic activity but little continuous long term data exist to understand this parameter the recent 2008 2018 lava lake activity at the summit of k lauea volcano provides an opportunity to track and understand the processes that control lava level over timescales ranging from minutes to years we review recently published data as well as analyze the long term record of lava level at k lauea s summit during 2009 2017 longer timescale fluctuations over days to months have a strong positive linear correlation with ground deformation suggesting they reflect pressure changes in the summit magma reservoir shorter timescale fluctuations over minutes to hours have an inverse relationship with spattering i e outgassing intensity at the lake surface increased outgassing lowers the lake level and vice versa our analysis of the long term lava level data thus confirms that lava level at halema uma u is controlled by these two types of processes 1 those related to magma reservoir pressure changes such as magma supply rate and 2 shallow outgassing fluctuations such as gas pistoning frequency filtering can isolate pressure and outgassing driven components of lava level change time series analysis indicates that there was no large persistent periodicity in the lava level a minor fortnightly oscillation might be related to earth tides but was not continuously present the correlation between lava level and deformation of the summit indicates that the lava lake acts as a reliable piezometer tracking lava level over time may thus provide an indication of flank eruptive potential we show that long term interdisciplinary monitoring is necessary to discriminate the processes that control lava level

stratigraphic correlations between the european project for ice coring in antarctica epica dome c and vostok ice cores showing the relative variations of snow accumulation over the past 45 kyr 1 high resolution chemistry analysis and electrical measurements performed on two ice core records european project for ice coring in antarctica epica dome c and vostok spanning the last 45 kyr allow stratigraphic correlations by matching volcanic events several common events were identified along the two ice cores on the basis of acidity and sulphate spikes in snow layers timescales were matched through comparison with isotope d profiles and using the antarctic cold reversal acr minimum a 10be peak and a dust spike as temporal checkpoints ratios of relative snow accumulation at the two sites during the holocene in the glacial interglacial transition and in the last part of the glacial period were reconstructed by finding the best fit between dome c and vostok depths recording the same events after accounting for thinning of the layers as they are buried within the glacier the dome c vostok accumulation ratio expected to be roughly constant from the conventional accumulation temperature isotope approach is 1 12 for the glacial period but increases to as much as 1 44 for a large part of the holocene glaciological effects mainly related to the geographic origin of the vostok ice along the ridge b vostok axis can account for only a minor fraction of this change instead we argue that accumulation variability between the cores stems from differential changes in atmospheric circulation during these respective climatic periods at the two sites regional changes in atmospheric circulation are proposed with a negative anomaly in dome c a positive accumulation anomaly in vostok or a combination of both during glacial climate our approach may help to improve ice core dating by 1 revealing anomalies in accumulation rate estimation based on the classical thermodynamic method and 2 supporting the necessity to take into account contributions due to changes in atmospheric circulation processes

seismic wave attenuation in methane hydrate bearing sediments vertical seismic profiling data from the nankai trough exploratory well offshore tokai central japan 1 data from two vertical seismic profiles vsps from the nankai trough exploratory well offshore tokai central japan are used to estimate compressional attenuation in methane hydrate mh bearing sediments at seismic frequencies of 30 110 hz we compare spectral ratio and centroid frequency shift methods for measuring attenuation to isolate intrinsic attenuation from total attenuation attenuation is computed from multiples using one dimensional synthetic vsp data from sonic and density logs the use of two different measurement methods and two vsps recorded at just 100 m separation provides an opportunity to validate the attenuation measurements no significant compressional attenuation was observed in mh bearing sediments at seismic frequencies macroscopically the peaks of highest attenuation in the seismic frequency range correspond to low saturation gas zones in contrast high compressional attenuation zones in the sonic frequency range 10 20 khz are affected by the presence of methane hydrates in the same well locations thus this study demonstrated the frequency dependence of attenuation in mh bearing sediments mh bearing sediments cause attenuation in the sonic frequency range rather than the seismic frequency range

sensitivity of chemical species to climatic changes in the last 45 kyr as revealed by high resolution dome c east antarctica ice core analysis

retrieval of volcanic ash particle size mass and optical depth from a ground based thermal infrared camera abstract volcanoes can emit fine sized ash particles 1 10 m radii into the atmosphere and if they reach the upper troposphere or lower stratosphere these particles can have deleterious effects on the atmosphere and climate if they remain within the lowest few kilometers of the atmosphere the particles can lead to health effects in humans and animals and also affect vegetation it is therefore of some interest to be able to measure the particle size distribution mass and other optical properties of fine ash once suspended in the atmosphere a new imaging camera working in the infrared region between 7 14 m has been developed to detect and quantify volcanic ash the camera uses passive infrared radiation measured in up to five spectral channels to discriminate ash from other atmospheric absorbers e g water molecules and a microphysical ash model is used to invert the measurements into three retrievable quantities the particle size distribution the infrared optical depth and the total mass of fine particles in this study we describe the salient characteristics of the thermal infrared imaging camera and present the first retrievals from field studies at an erupting volcano an automated ash alarm algorithm has been devised and tested and a quantitative ash retrieval scheme developed to infer particle sizes infrared optical depths and mass in a developing ash column the results suggest that the camera is a useful quantitative tool for monitoring volcanic particulates in the size range 1 10 m and because it can operate during the night it may be a very useful complement to other instruments e g ultra violet spectrometers that only operate during daylight

a comparison of the volcanic records over the past 4000 years from the greenland ice core project and dye 3 greenland ice cores since 1980 the electrical conductivity method ecm has been used to infer volcanic acid signals in greenland ice cores the method reveals the great majority of major volcanic eruptions including several known from historic records subsequent ion chromatographic analyses of the acid volcanic layers show the chemical composition i e the concentration of the volcanic acids h2so4 hci and hf plus e g the nonvolcanically derived hno3 while ecm data are available from a large number of shallow depth greenland ice cores covering the past 500 1500 years only the greenland ice core project grip greenland ice sheet project 2 gisp2 and dye 3 deep ice cores exist for a detailed comparative study of volcanic signals in greenland ice cores representing several thousand years comparison of the volcanic signals registered in the grip and gisp2 cores will be presented elsewhere the latter cores were augered 30 km apart and essentially represent the same atmospheric conditions such as temperature snow accumulation and chemical composition of the air here we present a comparison between the major volcanic signals over the past 4000 years in the grip core from central greenland and the dye 3 core from se greenland in order to investigate the depositional differences many of the major signals are detected in both cores but some of the differences in the records can be used to infer the latitudinal band of some eruption sites furthermore the influence of the amount of annual precipitation and glaciological postdepositional processes on the volcanic signals is discussed

quantitative imaging of volcanic plumes results needs and future trends abstract recent technology allows two dimensional imaging of trace gas distributions in plumes in contrast to older one dimensional remote sensing techniques that are only capable of measuring total column densities the new imaging methods give insight into details of transport and mixing processes as well as chemical transformation within plumes we give an overview of gas imaging techniques already being applied at volcanoes so2 cameras imaging doas ft ir imaging present techniques where first field experiments were conducted led lidar tomographic mapping and describe some techniques where only theoretical studies with application to volcanology exist e g fabry perot imaging gas correlation spectroscopy bi static lidar finally we discuss current needs and future trends in imaging technology

continuous measurements of sif 4 and so 2 by thermal emission spectroscopy insight from a 6 month survey at the popocatepetl volcano abstract the processes linked with the emplacement and growth destruction of a lava dome are of prime importance to understand the stability of such extrusions and assess the associated risks for local populations during the last couple of decades ground and space based spectroscopic techniques have been developed to monitor such processes from a safe distance such approaches significantly improved our knowledge about the relationship between the chemical composition of the volcanic gas plumes and both the deep and shallow volcanic processes leading to the different types of explosive activity the potential of the ground based thermal emission fourier transform infrared spectroscopy ftir remained under exploited due to the difficulty to properly handle the radiative transfer phenomena despite the drawbacks in the complex analytical requirements this method enables to continuously monitor day and night with a high temporal resolution 1 meas 3 min relevant gas species such as so 2 and sif 4 in the volcanic plumes previous studies have related the temporal variations of the sif 4 so 2 ratio in volcanic plumes to the onset of vulcanian explosions this study reports a 6 month so 2 sif 4 and sif 4 so 2 time series from january to june 2015 of the popocatepetl s gas plume obtained from ftir thermal emission spectroscopic measurements the infrared spectra were analyzed using the sfit4 radiative transfer and inverse model which we have adapted for this application we obtained highly variable sif 4 so 2 ratios with a mean value of 3 6 10 4 with the highest values around 3 10 3 measured during the final phase of a lava dome growth february march 2015 the rapid sif 4 so 2 variations were more carefully explored and compared for the first time with the seismic activity a remarkable coincidence between sharp sif 4 so 2 rises and the seismic events are evidenced here

image based correction of the light dilution effect for so2 camera measurements abstract ultraviolet so 2 cameras are increasingly used in volcanology because of their ability to remotely measure the 2d distribution of so 2 in volcanic plumes at a high frequency however light dilution i e the scattering of ambient photons within the instrument s field of view fov on air parcels located between the plume and the instrument induces a systematic underestimation of the measurements whose magnitude increases with distance so 2 content atmospheric pressure and turbidity here we describe a robust and straightforward method to quantify and correct this effect we retrieve atmospheric scattering coefficients based on the contrast attenuation between the sky and the increasingly distant slope of the volcanic edifice we illustrate our method with a case study at etna volcano where difference between corrected and uncorrected emission rates amounts to 40 to 80 and investigate the temporal variations of the scattering coefficient during 1 h of measurements on etna we validate the correction method at popocatepetl volcano by performing measurements of the same plume at different distances from the volcano finally we reported the atmospheric scattering coefficients for several volcanoes at different latitudes and altitudes

comparison of cospec and two miniature ultraviolet spectrometer systems for so2 measurements using scattered sunlight the correlation spectrometer cospec the principal tool for remote measurements of volcanic so2 is rapidly being replaced by low cost miniature ultraviolet uv spectrometers we compared two of these new systems with a cospec by measuring so2 column amounts at k lauea volcano hawaii the two systems one calibrated using in situ so2 cells and the other using a calibrated laboratory reference spectrum employ similar spectrometer hardware but different foreoptics and spectral retrieval algorithms accuracy signal to noise retrieval parameters and precision were investigated for the two configurations of new miniature spectrometer measurements included traverses beneath the plumes from the summit and east rift zone of k lauea and testing with calibration cells of known so2 concentration the results obtained from the different methods were consistent with each other with 8 difference in estimated so2 column amounts up to 800 ppm m a further comparison between the cospec and one of the miniature spectrometer configurations the flyspec spans an eight month period and showed agreement of measured emission rates to within 10 for so2 column amounts up to 1 600 ppm m the topic of measuring high so2 burdens accurately is addressed for the k lauea measurements in comparing the foreoptics retrieval methods and resultant implications for data quality we aim to consolidate the various experiences to date and improve the application and development of miniature spectrometer systems

two likely stratospheric volcanic eruptions in the 1450s c e found in a bipolar subannually dated 800 year ice core record 1 an 800 year volcanic record is constructed from high resolution chemical analysis of recently obtained west antarctica and central greenland ice cores the high accuracy and precision of the ice core chronologies are a result of dating by annual ice layer counting nineteen bipolar volcanic signals in this record represent large explosive eruptions in the tropics with probable climatic impact one of the two bipolar volcanic signals dated at 1453 and 1459 is probably left by the eruption of the submarine volcano kuwae in the tropical pacific one of the largest volcanic eruptions in the last millennium the discovery of the two signals in the 1450s casts doubt on the eruption year of 1452 or 1453 for kuwae based on previous ice core records the volcanic sulfate deposition patterns in this bipolar record suggest that the later signal is likely from the kuwae eruption in 1458 although a firm attribution is not possible sulfur isotope composition in the volcanic sulfate in the central greenland cores indicates that both eruptions in the 1450s injected sulfur gases into the stratosphere with probable impact on the global climate these results are in agreement with tree ring records showing two short cold episodes during that decade the bipolar volcanic record supports the hypothesis that unusually active volcanism in the thirteenth century contributed to the onset of the little ice age and another active period in the mid fifteenth century may have helped to sustain the little ice age

degassing processes during lava dome growth insights from santiaguito lava dome guatemala abstract eruptions of intermediate magma may be explosive or effusive the development of open system degassing has been proposed as a pre requisite for effusion of intermediate magma however processes leading to open system degassing are poorly understood to better understand degassing processes during lava dome extrusion we report high temporal resolution so2 emission rate measurements collected with an ultra violet imaging camera at santiaguito guatemala santiaguito is an ideal case study as the dome lava is compositionally very similar to products of the 1902 plinian eruption of the parental santa maria volcano we find that degassing is weak 0 4 1 kg s 1 but continuous and explosions are associated with small increases in emission rates up to 2 3 kg s 1 continuous repose degassing occurs through a shallow cap rock which likely represents a proto crust on the block lava flow which is extruded from the same vent the continual permeability of the upper conduit argues against a mechanism of explosion triggering in which gas pressure builds beneath a viscous cap rock or plug rather we consider degassing data better consistent with a model of shear fracturing at the conduit margins using field constraints we model the viscosity of santiaguito magma as a function of depth and show that conditions for shear fracturing are met from 150 600 m to the surface this is in line with independent estimates of explosion initiation depth we show that repose timescales are orders of magnitude longer than the timescale for shear fracture and suggest that explosions are triggered when a continuous network of smaller scale fractures develops at which point decompression occurs and an explosion is triggered fracture healing occurs by viscous relaxation however near to the surface where viscosity is highest an unconsolidated gouge layer may develop our model implies that the observed explosions are a by product of extrusion shear fracturing can drive open system degassing of crystal rich intermediate magma at shallow levels in the conduit as high magma viscosity is able to overcome the low strain rates associated with slow ascent of magma

a 12 000 year record of explosive volcanism in the siple dome ice core west antarctica 1 air mass trajectories in the southern hemisphere provide a mechanism for transport to and deposition of volcanic products on the antarctic ice sheet from local volcanoes and from tropical and subtropical volcanic centers this study extends the detailed record of antarctic south american and equatorial volcanism over the last 12 000 years using continuous glaciochemical series developed from the siple dome a sdma ice core west antarctica the largest volcanic sulfate spike 280 g l occurs at 5881 b c e other large signals with unknown sources are observed around 325 b c e 270 g l and 2818 b c e 191 g l ages of several large equatorial or southern hemisphere volcanic eruptions are synchronous with many sulfate peaks detected in the sdma volcanic ice chemistry record the microprobe fingerprinting of glass shards in the sdma core points to the following antarctic volcanic centers as sources of tephra found in the sdma core balenny island pleiades mount berlin mount takahe and mount melbourne as well as mount hudson and possibly mount burney volcanoes of south america identified volcanic sources provide an insight into the poorly resolved transport history of volcanic products from source volcanoes to the west antarctic ice sheet

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

holocene electrical and chemical measurements from the epica dome c ice core the comparison between electric electric conductivity measurement ecm and dielectric profiling dep and chemical sulphate and chloride depth profiles along the first 400 m of the epica dome c ice core revealed a very good fit especially for peaks related to volcanic emissions from the comparison between these profiles a dominant contribution of sulphuric acid to the ionic balance of antarctic ice for the holocene was confirmed a progressive increase with depth was observed for chloride concentrations showing a change of relative contribution between sulphate and chloride a higher increase of chloride was evident between 270 and 360 m depth probably due to a change in source or transport processes or to an increase of the annual snow accumulation rate the dep ecm and sulphate ice signatures of tambora ad 1816 and el chichon ad 1259 eruptions are described in detail a characteristic peak series due to hcl deposition was identified at 103 109 m depth from the ecm dep and chloride profiles

shallow degassing events as a trigger for very long period seismicity at kīlauea volcano hawai i the first eruptive activity at k lauea volcano s summit in 25 years began in march 2008 with the opening of a 35 m wide vent in halema uma u crater the new activity has produced prominent very long period vlp signals corresponding with two new behaviors episodic tremor bursts and small explosive events both of which represent degassing events from the top of the lava column previous work has shown that vlp seismicity has long been present at k lauea s summit and is sourced approximately 1 km below halema uma u by integrating video observations infrasound and seismic data we show that the onset of the large vlp signals occurs within several seconds of the onset of the degassing events this timing indicates that the vlp is caused by forces sourced at or very near the lava free surface due to degassing transmitted down the magma column and coupling to the surrounding rock at 1 km depth

relation between single very long period pulses and volcanic gas emissions at mt asama japan 1 multiple volcanic observations conducted at mt asama japan provide evidence of a link between single very long period vlp seismic pulses and volcanic gas emissions so2 flux measurements were conducted on 2 june 2009 when mt asama was producing ash free eruptions with vlp pulses gas bursts from a vent at the crater bottom following the vlp pulses provided an excellent opportunity to examine the relation directly the so2 emission for each eruption was calculated by integrating high temporal so2 flux data obtained by the so2 imaging system and subtracting the contribution from quiescent degassing from fumaroles around the crater bottom a seismic moment of vlp pulse was estimated by the waveform inversion we observed seven eruptions and obtained the proportional relation between vlp pulse moment and so2 emission the relation determined is consistent with the vlp source model these observational results are the first report of a quantitative comparison between single vlp pulse moment and volcanic gas emission

eight centuries of volcanic signal and climate change at talos dome east antarctica 1 during the 1996 programma nazionale di ricerche in antartide international trans antarctic scientific expedition traverse two firn cores were retrieved from the talos dome area east antarctica at elevations of 2316 m td 89 m long and 2246 m st556 19 m long cores were dated by using seasonal variations in non sea salt nss so42 concentrations coupled with the recognition of tritium marker level 1965 1966 and nss so42 spikes due to the most important volcanic events in the past pinatubo 1991 agung 1963 krakatoa 1883 tambora 1815 kuwae 1452 unknown 1259 the number of annual layers recognized in the td and st556 cores was 779 and 97 respectively the d record obtained from the td core has been compared with other east antarctic isotope ice core records dome c epica south pole taylor dome these records suggest cooler climate conditions between the middle of 16th and the beginning of 19th centuries which might be related to the little ice age lia cold period because of the high degree of geographical variability the strongest lia cooling was not temporally synchronous over east antarctica and the analyzed records do not provide a coherent picture for east antarctica the accumulation rate record presented for the td core shows a decrease during part of the lia followed by an increment of about 11 in accumulation during the 20th century at the st556 site the accumulation rate observed during the 20th century was quite stable

ground based measurements of spatial and temporal variability of snow accumulation in east antarctica the east antarctic ice sheet is the largest highest coldest driest and windiest ice sheet on earth understanding of the surface mass balance smb of antarctica is necessary to determine the present state of the ice sheet to make predictions of its potential contribution to sea level rise and to determine its past history for paleoclimatic reconstructions however smb values are poorly known because of logistic constraints in extreme polar environments and they represent one of the biggest challenges of antarctic science snow accumulation is the most important parameter for the smb of ice sheets smb varies on a number of scales from small scale features sastrugi to ice sheet scale smb patterns determined mainly by temperature elevation distance from the coast and wind driven processes in situ measurements of smb are performed at single points by stakes ultrasonic sounders snow pits and firn and ice cores and laterally by continuous measurements using ground penetrating radar smb for large regions can only be achieved practically by using remote sensing and or numerical climate modeling however these techniques rely on ground truthing to improve the resolution and accuracy the separation of spatial and temporal variations of smb in transient regimes is necessary for accurate interpretation of ice core records in this review we provide an overview of the various measurement techniques related difficulties and limitations of data interpretation describe spatial characteristics of east antarctic smb and issues related to the spatial and temporal representativity of measurements and provide recommendations on how to perform in situ measurements

a new continuous high resolution detection system for sulphate in ice cores sulphate so4 2 is a major ion found in polar ice cores and is related to different aerosol sources and processes explosive volcanic eruptions even far away can cause distinct sulphate peaks in ice core records thus a robust sulphate detection system which is suitable for fieldwork and which enables the measurement of sulphate at high temporal resolution is of great interest in this study we present the adaptation of a new continuous flow analysis system for sulphate that is based on a spectrophotometric method using dimethylsulfonazo iii and an inline reactor column containing barium sulphate particles the method shows a detection limit of 70 ng g 1 and a linear range up to at least 3000 ng g 1 it is simple robust and less prone to interferences compared to the previously used method

spatially resolved so2 flux emissions from mt etna we report on a systematic record of so2 flux emissions from individual vents of etna volcano sicily which we obtained using a permanent uv camera network observations were carried out in summer 2014 a period encompassing two eruptive episodes of the new south east crater nsec and a fissure fed eruption in the upper valle del bove we demonstrate that our vent resolved so2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of etna s shallow plumbing system structure we find that the fissure eruption contributed 50 000 t of so2 or 30 of the so2 emitted by the volcano during the 5 july to 10 august eruptive interval activity from this eruptive vent gradually vanished on 10 august marking a switch of degassing toward the nsec onset of degassing at the nsec was a precursory to explosive paroxysmal activity on 11 15 august

development of an ultra violet digital camera for volcanic so2 imaging abstract in an effort to improve monitoring of passive volcano degassing we have constructed and tested a digital camera for quantifying the sulfur dioxide so 2 content of volcanic plumes the camera utilizes a bandpass filter to collect photons in the ultra violet uv region where so 2 selectively absorbs uv light so 2 is quantified by imaging calibration cells of known so 2 concentrations images of volcanic so 2 plumes were collected at four active volcanoes with persistent passive degassing villarrica located in chile and santiaguito fuego and pacaya located in guatemala images were collected from distances ranging between 4 and 28 km away with acceptable detection up to approximately 16 km camera set up time in the field ranges from 5 10 min and temporal resolution of up to 6 images per minute is possible which combined with the camera s field of view makes a continuous so 2 dataset attainable variable in plume concentrations can be observed and accurate plume speeds or rise rates can readily be determined by tracing individual portions of the plume within sequential images initial fluxes computed from camera images require a correction for the effects of environmental light scattered into the field of view at fuego volcano simultaneous measurements of corrected so 2 fluxes with the camera and a correlation spectrometer cospec agreed within 25 experiments at the other sites were equally encouraging and demonstrated the camera s ability to detect so 2 under variable background meteorological and environmental conditions this early work has shown great success in imaging so 2 plumes and offers promise for volcano monitoring due to its rapid deployment and data processing capabilities relatively low cost and improved interpretation afforded by synoptic coverage from a range of distances

comparison of analytical methods used for measuring major ions in the epica dome c antarctica ice core in the past ionic analyses of deep ice cores tended to consist of a few widely spaced measurements that indicated general trends in concentration the ion chromatographic methods widely used provide well validated individual data but are time consuming the development of continuous flow analysis cia methods has allowed very rapid high resolution data to be collected in the field for a wide range of ions in the european project for ice coring in antarctica epica deep ice core drilling at dome c many ions have been measured at high resolution and several have been analyzed by more than one method the full range of ions has been measured in five different laboratories by ion chromatography ic at resolutions of 2 5 10 cm in the field cia was used to measure the ions na ca2 nitrate and ammonium additionally a new semi continuous in situ ic method fast ion chromatography fic was used to analyze sulphate nitrate and chloride some data are now available to 788 in depth in this paper we compare the data obtained by the three methods and show that the rapid methods cia and fic give an excellent indication of trends in ionic data differences between the data from the different methods do occur and in some cases these are genuine being due to differences in speciation in the methods we conclude that the best system for most deep ice core analysis is a rapid system of cia and fic along with in situ meltwater collection for analysis of other ions by ic but that material should be kept aside for a regular check on analytical quality and for more detailed analysis of some sections