continuous monitoring of fumarole temperatures at mount etna italy abstract in this paper we present the first data of temperature continuously recorded in two fumarole fields designated vor and hor located in the summit area of mount etna volcano italy the time series embraces two distinct periods 1 october 2007 to november 2009 during which an effusive eruption occurred from may 2008 to july 2009 and 2 november 2011 to june 2012 characterized by the occurrence of strong paroxysms fire fountains and lava flow the analysis of the temperature signal in both the time and frequency domains and its comparison with meteorological observations allowed us to separate the exogenous influences from the effects of variations in the activity state of the volcano the acquired data were weakly affected by seasonal cycles of the air temperature and strongly affected by the rainfall optimization of site conditions i e sensor depth and soil permeability markedly reduced meteorological disturbances the distance from the main degassing and or eruptive fractures was crucial to maximizing the probability of the technical survival of the monitoring apparatus which was seriously affected by the emission of acidic gases tephra fallout and lava flows apart from the exogenous influences the most appreciable variation was observed at vor where a huge increase in fumarole temperature was detected immediately after the onset of the 2008 2009 eruption such an anomalous increase was attributed to the rapid ascent of magma feeding the eruptive fracture another abrupt increase in temperature was recorded at hor in march and april 2012 during this period the frequency of paroxysm occurrence increased markedly and this led us to hypothesize that the thermal anomaly was due to the intrusion of a new batch of magma in the conduits of the southeast crater medium to long term monitoring weeks to months of fumarole temperatures revealed variations that were attributed to pressurization depressurization phases of the shallow volcanic system which varied between the various monitored sectors of the volcano our observations suggest that continuous monitoring of fumarole temperature can give useful information about the activity of mount etna moreover due to the complexity of its shallow plumbing system we conclude that the monitoring systems should be extended to cover the entire fumarole network of the summit area

unrest signals after 46 years of quiescence at cumbre vieja la palma canary islands abstract monogenetic eruptions are the most common volcanic activity in the world however unrest monitoring data are scarce due to the long intervening quiescence periods this study analyzes unrest signals recorded in one of the largest monogenetic fields in the canary islands cumbre vieja la palma two seismic swarms were registered in october 2017 and february 2018 with b values of 1 6 0 1 and 2 3 0 2 respectively suggesting an intense magmatic fluids contribution gas and or magma both swarms were linked to changes in gas emissions increases in hydrogen concentration and r ra c up to 7 52 0 05 were recorded before the first swarm at the sampling point closest to where seismicity was located indicating a deep gas input after the second swarm increases in r ra c and thoron soil concentration were recorded at two locations this dataset is compatible with a stalled magmatic intrusion at ca 25 km depth with an estimated volume between 5 5 10 4 km3 and 3 10 2 km3

dynamics of mild strombolian activity on mt etna abstract here we report the first measurements of gas masses released during a rare period of strombolian activity at the bocca nuova crater mt etna sicily uv camera data acquired for 195 events over an 27 minute period 27th july 2012 indicate erupted so2 masses ranging from 0 1 to 14 kg per event with corresponding total gas masses of 0 1 to 74 kg thus the activity was characterised by more frequent and smaller events than typically associated with strombolian activity on volcanoes such as stromboli events releasing larger measured gas masses were followed by relatively long repose periods before the following burst a feature not previously reported on from gas measurement data if we assume that gas transport within the magma can be represented by a train of rising gas pockets or slugs then the high frequency of events indicates that these slugs must have been in close proximity in this case the longer repose durations associated with the larger slugs would be consistent with interactions between adjacent slugs leading to coalescence a process expedited close to the surface by rapid slug expansion we apply basic modelling considerations to the measured gas masses in order to investigate potential slug characteristics governing the observed activity we also cross correlated the acquired gas fluxes with contemporaneously obtained seismic data but found no relationship between the series in line with the mild form of manifest explosivity

spectroscopic evidence for a lava fountain driven by previously accumulated magmatic gas the eruption of mount etna in 2000 was notable for an exceptional series of 64 periodic lava fountains propelling lava fragments to heights of up to 900 metres it has been difficult to determine which of two suggested sources of power gas release from the magma itself during its rapid ascent or a build up of pressure from gas accumulated at depth is the driving force for these dramatic jets but one of the etna fountains provided volcanologists with the opportunity to use remote sensing not that remote see picture on the following page to determine the infrared spectra of the gas phase this revealed the chemical composition of the gas that powered this fountain as consistent with an origin in an accumulated gas layer lava fountains are spectacular continuous gas jets propelling lava fragments to heights of several hundred metres which occasionally occur during eruptions of low viscosity magmas1 2 3 4 5 whether they are generated by the effervescent disruption of fast rising bubbly melt2 3 4 5 or by the separate ascent of a bubble foam layer accumulated at depth6 7 still remains a matter of debate8 no field measurement has yet allowed firm discrimination between these two models a key insight into the origin of lava fountains may be gained by measuring the chemical composition of the driving gas phase this composition should differ markedly depending on whether the magma degassing occurs before or during eruption9 10 here we report the analysis of magmatic gas during a powerful 250 600 m high lava fountain measured with fourier transform infrared spectroscopy11 12 13 14 on mount etna sicily the abundances of volcanic gas species determined from absorption spectra of lava radiation reveal a fountain gas having higher co2 s and s cl ratios than other etnean emissions14 15 16 17 18 and which cannot derive from syn eruptive bulk degassing of etna basalt19 20 instead its composition suggests violent emptying of a gas bubble layer previously accumulated at about 1 5 km depth below the erupting crater

gas emissions from failed and actual eruptions from cook inlet volcanoes alaska 1989 2006 cook inlet volcanoes that experienced an eruption between 1989 and 2006 had mean gas emission rates that were roughly an order of magnitude higher than at volcanoes where unrest stalled for the six events studied mean emission rates for eruptions were 13 000 t d co2 and 5200 t d so2 but only 1200 t d co2 and 500 t d so2 for non eruptive events failed eruptions statistical analysis suggests degassing thresholds for eruption on the order of 1500 and 1000 t d for co2 and so2 respectively emission rates greater than 4000 and 2000 t d for co2 and so2 respectively almost exclusively resulted during eruptive events the only exception being two measurements at fourpeaked while this analysis could suggest that unerupted magmas have lower pre eruptive volatile contents we favor the explanations that either the amount of magma feeding actual eruptions is larger than that driving failed eruptions or that magmas from failed eruptions experience less decompression such that the majority of h2o remains dissolved and thus insufficient permeability is produced to release the trapped volatile phase or both in the majority of unrest and eruption sequences increases in co2 emission relative to so2 emission were observed early in the sequence with time all events converged to a common molar value of c s between 0 5 and 2 these geochemical trends argue for roughly similar decompression histories until shallow levels are reached beneath the edifice i e from 20 35 to 4 6 km and perhaps roughly similar initial volatile contents in all cases early elevated co2 levels that we find at these high latitude andesitic arc volcanoes have also been observed at mid latitude relatively snow free basaltic volcanoes such as stromboli and etna typically such patterns are attributed to injection and decompression of deep co2 rich magma into a shallower chamber and open system degassing prior to eruption here we argue that the c s trends probably represent tapping of vapor saturated regions with high c s and then gradual degassing of remaining dissolved volatiles as the magma progresses toward the surface at these volcanoes however c s is often accentuated due to early preferential scrubbing of sulfur gases the range of equilibrium degassing is consistent with the bulk degassing of a magma with initial co2 and s of 0 6 and 0 2 wt respectively similar to what has been suggested for primitive redoubt magmas

temperature dependence of sulfide and sulfate solubility in olivine saturated basaltic magmas abstract the sulfur concentration at pyrrhotite and anhydrite saturation in primitive hydrous basaltic melt of the 2001 2002 eruption of mt etna was determined at 200 mpa t 1050 1250 c and at log fo2 from fmq to fmq 2 2 fmq is fayalite magnetite quartz oxygen buffer at 1050 c au sample containers were used a double capsule technique using a single crystal olivine sample container closed with an olivine piston embedded in a sealed au80pd20 capsule was developed to perform experiments in s bearing hydrous basaltic systems at t 1050 c pyrrhotite is found to be a stable phase coexisting with melt at fmq fmq 0 3 whereas anhydrite is stable at fmq 1 4 fmq 2 2 the s concentration in the melt increases almost linearly from 0 12 0 01 to 0 39 0 02 wt s at fes saturation and from 0 74 0 01 to 1 08 0 04 wt s at anhydrite saturation with t ranging from 1050 1250 c the relationships between s concentration at pyrrhotite and or anhydrite saturation mgo content of the olivine saturated melt t and log fo2 observed in this study and from previous data are used to develop an empirical model for estimating the magmatic t and fo2 from the s and mgo concentrations of h2o bearing olivine saturated basaltic melts the model can also be used to determine maximum s concentrations if fo2 and mgo content of the melt are known the application of the model to compositions of melt inclusions in olivines from mt etna indicates that the most primitive magmas trapped in inclusions might have been stored at log fo2 slightly higher than fmq 1 and at t 1100 1150 c whereas more evolved melts could have been trapped at t 1100 c these values are in a good agreement with the estimates obtained by other independent methods reported in the literature

hydrogen in the gas plume of an open vent volcano mount etna italy 1 we report here on the first hydrogen determinations in the volcanic gas plume of mount etna in italy which we obtained during periodic field surveys on the volcano s summit area with an upgraded multigas using a specific ezt3hyt electrochemical sensor we resolved h2 concentrations in the plume of 1 3 ppm above ambient background atmosphere and derived h2 so2 and h2 h2o plume molar ratios of 0 002 0 044 mean 0 013 and 0 0001 0 0042 mean 0 0018 respectively taking the above h2 so2 ratios in combination with a time averaged so2 flux of 1600 gg yr 1 we evaluate that etna contributes a time averaged h2 flux of 0 65 gg yr 1 suggesting that the volcanogenic contribution to the global atmospheric h2 budget 70 000 100 000 gg yr 1 is marginal we also use our observed h2 h2o ratios to propose that etna s passive plume composition is at least partially representative of a quenched temperatures between 750 c and 950 c equilibrium in the gas magma system at redox conditions close to the nickel nickel oxide nno mineral buffer the positive dependence between h2 so2 h2 h2o and co2 so2 ratios suggests that h2 is likely supplied at least in part by deeply rising co2 rich gas bubbles fluxing through a co2 depleted shallow conduit magma

forecasting etna eruptions by real time observation of volcanic gas composition it is generally accepted but not experimentally proven that a quantitative prediction of volcanic eruptions is possible from the evaluation of volcanic gas data by discussing the results of two years of real time observation of h2o co2 and so2 in volcanic gases from mount etna volcano we unambiguously demonstrate that increasing co2 so2 ratios can allow detection of the pre eruptive degassing of rising magmas quantitative modeling by the use of a saturation model allows us to relate the pre eruptive increases of the co2 so2 ratio to the refilling of etna s shallow conduits with co2 rich deep reservoir magmas leading to pressurization and triggering of eruption the advent of real time observations of h2o co2 and so2 combined with well constrained models of degassing represents a step forward in eruption forecasting

characterization and interpretation of volcanic activity at karymsky volcano kamchatka russia using observations of infrasound volcanic emissions and thermal imagery 2 a multiparameter data set including measurements of infrasound volcanic emissions and thermal imagery is used to characterize and interpret diverse volcanic activity observed during field campaigns in august 2011 and july 2012 at karymsky volcano kamchatka russia four activity types are visually identified and characterized according to so2 emission rate ash mass event duration peak temperature thermal radiation energy infrasound onset and frequency reduced infrasonic pressure and acoustic energy these activity types include 1 ash explosions 2 pulsatory degassing 3 gas jetting and 4 explosive eruption unique infrasound signals are associated with all four activity types suggesting that infrasound can be used to help remotely and continuously detect and characterize volcanic activity at karymsky and other similar volcanoes our observations suggest that so2 is emitted continuously though in varying abundance while ash is emitted discontinuously and is only associated with certain types of activity our data set supports previous models that attribute variations in surface activity to changes in conduit permeability at karymsky volcano evidence for a decrease in conduit permeability as a trigger for ash explosions and explosive eruption activity types is supported by weakened but still detectable so2 emission rates prior to eruption along with the highly impulsive infrasonic onset and large reduced infrasound pressure indicating high pressure at the vent we speculate that changes in conduit permeability at karymsky volcano result from changes in magma supply from the shallow crustal storage region though additional measurements are required to validate this hypothesis

gas and ash emissions associated with the 2010 present activity of sinabung volcano indonesia abstract sinabung volcano sumatra indonesia awoke from over 1200 years of dormancy with multiple phreatic explosions in 2010 after a period of quiescence sinabung activity resumed in 2013 producing frequent explosions lava dome extrusion and pyroclastic flows from dome and lava flow collapses becoming one of the world s most active volcanoes and displacing over 20 000 citizens this study presents a compilation of the geochemical datasets collected by the indonesian center for volcanology and geological hazard mitigation cvghm from 2010 current 2016 which provides insights into the evolution of the eruption based on observations of so2 emissions ash componentry ash leachate chemistry and bulk ash geochemistry the eruption can be split into six distinct geochemical phases the initial stage of phreatic summit explosions phase a occurred from august september 2010 during which background so2 emissions averaged 550 180 t d 1 s d an eruptive pause phase b starting in october 2010 abruptly ended in september 2013 with a resumption of conduit clearing eruptions phase c this third phase had a relatively modest background so2 emission rate avg 430 310 t d and produced ash consisting of accidental ejecta with high s cl leachate molar ratios 12 0 8 2 max 34 suggestive of deep sourced magma and or the incorporation of hydrothermal sulfur bearing phases lava extrusion at the summit phase d began in mid december 2013 and was accompanied by relatively low so2 emission rates 360 200 t d and lower but variable s cl leachate ratios 6 3 8 5 the most intense phase of the eruption phase e occurred from mid january to late february 2014 following a major lava dome collapse this period included increased lava extrusion rates dozens of large eruptions per day high so2 emission rates average 1680 1070 t d peak 3800 t d and a dramatic drop in s cl ash leachates to ratios average 1 4 0 5 consistent with increased degassing from shallow magma and the clearing out of sulfurous phases from the old hydrothermal system from march 2014 through the time of writing september 2016 sinabung settled into a relatively steady state of lower activity phase f ash emissions now consist of dominantly juvenile andesitic dacitic material with low s cl leachate ratios average 1 1 0 6 in august 2016 so2 emissions started being measured in a continuous manner using a network of permanent scanning doas instruments background so2 emission rates average 450 290 t d for the entirety of phase f but have been progressively decreasing to an average of 250 300 t d since june 2016 this long term gradual decline in so2 emission rates at sinabung since early 2014 is consistent with an apparent decrease in magma supply and lava effusion rates our conceptual degassing model suggests that large explosions and pyroclastic flows could continue in the near term owing to conduit plugging and dome collapses remaining a major threat until the magma supply rate decreases further and the eruption ends

qp structure of mount etna constraints for the physics of the plumbing system 1 in this study we present the three dimensional qp structure of the mount etna volcano italy obtained by using local earthquake data the attenuation along ray paths t computed from the high frequency decay of velocity spectra is used to reconstruct the deep structure of the volcano down to 15 km depth the tomographic images reveal two broad low qp anomalies at 0 and 3 km depth located to the south and southwest of the summit area and extending at depth to the west of a central high qp anomaly located between 6 and 15 km depth the joint analysis of p wave attenuation and velocity allows us to better constrain the physics of the plumbing system the shallow low qp anomalies are associated with high vp anomalies beneath the top of the volcano and normal low vp toward its western borders we interpret the regions of low qp and normal low vp as shallow volumes where magmatic fluids are stored conversely the low qp high vp region may indicate intensely fractured rock volumes filled by fluids surrounding the magma branches at depth the low qp anomaly defines the path of the magma ascent to the west of an extremely high qp high vp volume located beneath the southeastern side of the summit area the high qp high vp body is interpreted to be the compact solidified high density intrusive body formed by nonerupted material during past volcano activity

melt inclusion record of the conditions of ascent degassing and extrusion of volatile rich alkali basalt during the powerful 2002 flank eruption of mount etna italy 1 two unusual highly explosive flank eruptions succeeded on mount etna in july august 2001 and in october 2002 to january 2003 raising the possibility of changing magmatic conditions here we decipher the origin and mechanisms of the second eruption from the composition and volatile h2o co2 s cl content of olivine hosted melt inclusions in explosive products from its south flank vents our results demonstrate that powerful lava fountains and ash columns at the eruption onset were sustained by closed system ascent of a batch of primitive volatile rich 4 wt basaltic magma that rose from 10 km depth below sea level bsl and suddenly extruded through 2001 fractures maintained opened by eastward flank spreading this magma the most primitive for 240 years probably represents the alkali rich parental end member responsible for etna lavas evolution since the early 1970s few of it was directly extruded at the eruption onset but its input likely pressurized the shallow plumbing system several weeks before the eruption this latter was subsequently fed by the extrusion and degassing of larger amounts of the same but slightly more evolved magma that were ponding at 6 4 km bsl in agreement with seismic data and with the lack of preeruptive so2 accumulation above the initial depth of sulphur exsolution 3 km bsl we find that while ponding this magma was flushed and dehydrated by a co2 rich gas phase of deeper derivation a process that may commonly affect the plumbing system of etna and other alkali basaltic volcanoes

transition from dome forming to plinian eruptive styles controlled by h2o and cl degassing the transition from a plinian pumice to an effusive dome forming eruptive style is frequently observed in volcanic systems and is generally attributed to the progressive loss of volatiles from magma stored in a superficial reservoir this explosive effusive transition has been explained by the evolution from a closed to an open system of degassing1 2 3 4 but in this context an eruption at mt pelee martinique french west indies dated at 650 years ago which exhibited a rarely observed5 6 succession from dome forming to plinian activity in a short interval of time7 is at odds with such an explanation in this eruption near surface explosions of the dome produced two peleean turbulent pyroclastic flows whose deposits are similar to those of the effusive 1902 eruption and then plinian activity produced pumice fallouts and flows the reconstruction of the degassing paths of both eruptive regimes using the densities and the h2o and cl contents of the clasts shows that the interaction of rising magma with hydrothermal fluids at shallow depth may play a critical role in determining eruptive style

long term record of co2 degassing along mt etna s flanks and its relationship with magma dynamics and eastern flank instability a record of soil co2 flux data on the lower flanks of mt etna measured from 1989 to 2008 is discussed in the framework of multidisciplinary observations including seismicity ground deformations and flank instability a huge increase in soil co2 fluxes appears to be related to the dynamics of magma ascent in the upper portions of the volcano 0 3 km and the intrusion of dykes along the southern rift as mainly observed before the 1991 93 eruption even after the 1991 93 eruption the recharge of the shallow central reservoir was accompanied by a long term increase in soil co2 degassing mainly in the southwestern area the 2001 eruption marked dramatic changes in the areal distribution of seismicity the deformation pattern and the soil co2 degassing indeed while the soil co2 degassing showed background values in the southwestern area it progressively increased in the eastern sector and along the pernicana fault this has been related to the marked sliding of the eastern flank since the 2002 03 eruption and the associated seismicity this study provides evidence that the extent of soil co2 degassing on the lower flanks of mt etna is controlled by 1 the volume of involved magma 2 the intrusion of dykes in the upper parts of the volcano and 3 fault movement and seismicity this implies that different degassing structures must be monitored simultaneously when attempting to understand the behavior of the volcano as a whole

chlorine partitioning between a basaltic melt and h2o co2 fluids at mount etna abstract partitioning experiments between a basaltic melt from mt etna and a low density hydrous fluid or vapor containing h 2 o or h 2 o co 2 were performed at 1200 1260 c at pressures between 1 and 200 mpa either near the nickel nickel oxide nno buffer or at two log units above it nno 2 and with different chloride concentrations most of the experiments were done at chloride brine undersaturated conditions although at the highest cl concentrations explored brine saturation might have been reached the average partition coefficients d cl fluid melt over the range of cl concentrations were derived on a weight basis by plotting the calculated concentrations of cl in the fluid phase versus the measured ones in the melt for h 2 o cl experiments in which the cl concentration in the melt was 0 4 wt a negative dependence between d cl f m and pressure is observed d cl fluid melt in h 2 o cl bearing experiments ranges between 11 14 at 1 and 25 mpa to 6 at 200 mpa at nno and between 4 at 50 mpa and 13 at 100 mpa at nno 2 addition of co 2 at nno yields lower partition coefficients than in co 2 free conditions over the pressure range investigated the negative pressure dependence observed for h 2 o cl experiments disappears when co 2 is present in the system overall once co 2 is introduced in the system cl fugacity in the silicate melt tends to increase thus resulting in a decrease of d cl f m application to mt etna shows that the composition of the volcanic plume in terms of cl records very shallow pressures of magma equilibration with its exsolved fluid

continuous monitoring of hydrogen and carbon dioxide at mt etna article i nfo this study assessed the use of an h2 fuel cell as an h2 selective sensor for volcano monitoring the resolution repeatability and cross sensitivity of the sensor were investigated and evaluated under known laboratory conditions a tailor made device was developed and used for continuously monitoring h2 and co2 at mt etna throughout 2009 and 2010 the temporal variations of both parameters were strongly correlated with the evolution of the volcanic activity during the monitoring period in particular the co2 flux exhibited long term variations while h2 exhibited pulses immediately before the explosive activity that occurred at mt etna during 2010

monitoring of jokulhlaups and element fluxes in proglacial icelandic rivers using osmotic samplers the quantification of volatile emissions from volcanoes is an integral part of understanding magmatic systems with the exsolution and extent of volcanic degassing having a large impact on the nature of an eruption measurements of volatiles have traditionally focused on gas emissions into the atmosphere but volatiles can also become dissolved in proximal water bodies en route to the surface thus the monitoring of rivers draining active volcanic areas can provide insights to identifying changes in activity this process is particularly important for sub glacial volcanoes in iceland where much of the volatile release is transported within glacial outbreak floods termed jokulhlaups monitoring and characterising these phenomena is hampered by the dependence on spot sampling of stochastic events under challenging field conditions which often leads to bias in the collected data a recent technological advance is the osmotic sampler an electricity free pump that continuously collects water that can subsequently be divided into time averaged samples this technique allows for continued and unsupervised deployment of a sampler for weeks to months representing a cost efficient form of chemical monitoring in this study we deployed osmotic samplers in two rivers in southern iceland skalm is a proglacial river from m rdalsjokull glacier and katla volcano while skafta is a larger drainage system from the western part of vatnajokull glacier both rivers are prone to jokulhlaups from geothermal and volcanic sources and a small jokulhlaup of geothermal origin occurred during the second deployment in skafta in january 2014 the two deployments show that osmotic samplers are capable of delivering accurate chemical data in turbulent conditions for several key elements total dissolved fluxes for the deployment at skafta are calculated to be na 9 9 tonnes day mg 10 5 t d si 34 7 t d cl 11 0 t d ca 31 6 t d dic 50 8 t d and so4 28 3 t d with significant elevations of element concentrations during the jokulhlaup dissolved fluxes vary considerably on temporal scales from days to seasons so that spot sampling may miss pulses in concentrations this is particularly important for elements such as mn the continuous geochemical records from the osmotic samplers make it possible to identify pulses of fluxes attributed to sea spray groundwater and subglacial sources the samplers can also be combined with existing methods of river monitoring such as conductivity and discharge to accurately assess changes to fluvial chemistry due to volcanic inputs moreover there is the potential to deploy osmotic samplers in a range of other affected water bodies e g wells springs lakes to gain further insights into volcanic processes

fumarole compositions and mercury emissions from the tatun volcanic field taiwan results from multi component gas analyser portable mercury spectrometer and direct sampling techniques gas emissions from tatun volcanic group northern taiwan were studied for the first time using a multi component gas analyser system multi gas in combination with giggenbach flask methods at fumaroles and mud pools at da you keng dyk and geng tze ping gzp co 2 s molar ratios observed at dyk ranged from 3 17 similar ratios were observed using a multi gas sensor box of 8 16 so 2 at gzp was low higher concentrations were observed at dyk where so 2 h 2 s ratios were close to 1 for both methods a lower co 2 h 2 s ratio was measured via giggenbach flask sampling 7 2 than was found in the plume using the gas sensor at gzp 9 2 this may reflect rapid oxidation of h 2 s as it mixes with background air gaseous elemental mercury gem levels were observed in the fumarole gases using a portable mercury spectrometer these are the first such measurements of mercury at tatun mean gem concentrations in the fumarole plumes were 20 ng m 3 with much higher concentrations observed close to the ground mean gem 130 and 290 ng m 3 at dyk and gzp respectively the gem in the fumarole plume was elevated above concentrations in industrial urban air in northern taiwan and the increase in gem observed when the instrument was lowered suggests high levels of mercury are present in the surrounding ground surface the gem co 2 10 8 and gem s 10 6 ratios observed in the fumarole gases were comparable to those observed at other low temperature fumaroles combining the hg co 2 ratio with a previous co 2 flux value for the area the annual gem flux from the tatun field is estimated as 5 50 kg year 2008 elsevier b v all rights reserved

2001 flank eruption of the alkali and volatile rich primitive basalt responsible for mount etna s evolution in the last three decades abstract since the early 1970s enhanced eruptive activity of mount etna has been accompanied by selective geochemical changes in erupted lavas among which a gradual increase of alkalis whose origin is still debated here we provide further insight into the origin of this recent evolution based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase poor primitive basalt that was extruded during a highly explosive flank eruption in july august 2001 two types of lava were erupted simultaneously along a n s fracture system trachybasalts from the upper vents 2950 2700 m were simply drained out by fracturing of the central volcanic conduit they are identical to summit crater lavas and contain mg poor olivines fo 70 72 with evolved and volatile poor melt inclusions that represent late stage crystallisation during shallow open conduit degassing in contrast plagioclase poor basalt 80 of total extruded through the lower vents 2550 2100 m derived from lateral dyke intrusion of a more primitive and volatile rich magma across the sedimentary basement this primitive melt is best preserved in rare fo 82 4 80 5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent its high dissolved contents of h 2 o 3 4 wt co 2 0 11 to 0 41 wt s 0 32 wt cl 0 16 wt and f 0 094 wt point to its closed system ascent from 400 to 250 mpa 12 to 6 5 km depth b s l however the predominance of euhedral olivine phenocrysts with common reverse zoning cores fo 76 78 and rims fo 78 80 and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting the few preserved inclusions in these olivines indicate pre eruptive storage of that magma body at about 5 km depth b s l in coherence with seismic data we propose that the 2001 flank eruption resulted from gradual overpressuring of etna s shallow plumbing system due to the influx of volatile rich primitive basalt that may have begun several months in advance we find that this basalt is much richer in alkalis 2 0 wt k 2 o and has higher s cl 2 0 but lower cl k and cl f ratios than all pre 1970s etnean lavas 1 4 wt k 2 o s cl 1 5 as further exemplified by melt inclusions in entrained olivine xenocrysts combining these new observations with previously published data we argue that the 2001 basalt represents a new alkali rich basic end member feeding mt etna only few amount of which had previously been extruded during a 1974 peripheral eruption and more recently during brief paroxysmal summit events over the last three decades this new magma has progressively mixed with and replaced the former k poorer trachybasalts filling the plumbing system leading to extrusion of gradually more primitive and alkali richer lavas its geochemical singularities cannot result from shallow crustal contaminations instead they suggest the involvement of an alkali richer but cl poorer arc type component during recent magma genesis beneath etna

h2s fluxes from mt etna stromboli and vulcano italy and implications for the sulfur budget at volcanoes abstract we present here new measurements of sulfur dioxide and hydrogen sulfide emissions from vulcano etna and stromboli italy made by direct sampling at vents and by filter pack and ultraviolet spectroscopy in downwind plumes measurements at the f0 and fa fumaroles on vulcano yielded so 2 h 2 s molar ratios of 0 38 and 1 4 respectively from which we estimate an h 2 s flux of 6 to 9 t d 1 for the summit crater for mt etna and stromboli we found so 2 h 2 s molar ratios of 20 and 15 respectively which combined with so 2 flux measurements suggest h 2 s emission rates of 50 to 113 t d 1 and 4 to 8 t d 1 respectively we observe that source and plume so 2 h 2 s ratios at vulcano are similar suggesting that hydrogen sulfide is essentially inert on timescales of seconds to minutes this finding has important implications for estimates of volcanic total sulfur budget at volcanoes since most existing measurements do not account for h 2 s emission

rates of carbon dioxide plume degassing from mount etna volcano 1 we report here on the real time measurement of co2 and so2 concentrations in the near vent volcanic gas plume of mount etna acquired by the use of a field portable gas analyzer during a series of periodic field surveys on the volcano s summit during the investigated period september 2004 to september 2005 the plume co2 so2 ratio ranged from 1 9 to 10 8 with contrasting composition for northeast and voragine crater plumes scaling the above co2 so2 ratios by uv spectroscopy determined so2 emission rates we estimate co2 emission rates from the volcano in the range 0 9 67 5 kt d 1 average 9 kt d 1 about 2 kt of co2 were emitted daily on average during quiescent passive degassing whereas co2 emission rates from etna s summit were 10 40 times larger during the 2004 2005 effusive event with a cumulative co2 release of 3800 kt during the 6 months of the eruption such a syneruptive increase ascribed to the replenishment of the shallow 6 km volcanic plumbing system by co2 rich 0 25 wt more primitive magmas supports the potential of co2 output rates as key parameters for volcanic hazard assessment

thermal evolution of a thicker kreep liquid layer we consider the thermal evolution of the thickened potassium rare earth element and phosphorous kreep liquid layer that extends over a significant fraction of the lunar nearside with a prescribed thickness and heat production and beneath an insulating anorthosite crust this layer represents a subcrustal heat source beneath the procellarum imbrium terrane and may be responsible for the localized and anomalous enrichments of highly incompatible elements in this terrane in some models this thickened liquid layer is the thermal source for the remelting of mare basalts and also produces the parent magmas of the magnesian suite indeed a kreep liquid layer thickened from 5 to 10 km with more than 200 times chondritic heat producing elements does not continue to cool but undergoes a reheating and grows in thickness by dissolving several times its mass of anorthosite and ultramafic cumulates however such a liquid layer cannot give rise to the parent magmas to the magnesian suite because it cannot account for the extraordinarily high incompatible element content the primitive major element content or the positive end of the magnesian suite this growing layer will also form an impenetrable barrier to the eruption of mare basalts and is generally inconsistent with a number of geophysical constraints of the moon specifically the existence of mascons subsequent to the basin filling by mare basalts a thickened kreep liquid layer can however explain the asymmetry in the distribution of kreep rich rock on the lunar crust such a kreep layer must be efficiently cooled and be quickly solidified to avoid some of the difficulties described above a thinned anorthosite crust would allow efficient heat loss and induce crystallization of such a layer early in lunar history

aerosol formation in basaltic lava fountaining eyjafjallajokull volcano iceland 1 a short lived episode of basaltic lava fountaining at eyjafjallajokull volcano march april 2010 produced a low altitude ash poor plume we measured the composition of aerosol particles sampled using a cascade impactor and filter packs gases sampled using filter packs and volatile species scavenged by scoria and external water in order to investigate the formation and speciation of near source aerosol 0 4 m and its composition was dominated by chloride rather than sulfate we used two thermodynamic equilibrium models e aim and hsc chemistry v5 1 to show that the formation of particulate cl by condensation of hcl gas is more responsive to changes in ambient temperature than the oxidation of so2 to so42 so that a low so42 cl ratio in aerosol particles is characteristic of volcanic emissions in cold climates field measurements suggested that the efficiency of so2 to so42 conversion inside the vent increased with lower explosivity volatiles adsorbed on the surface of scoria had significantly higher so42 halogen molar ratios than the aerosol samples several potential explanations for these differences are discussed

melt inclusions track pre eruption storage and dehydration of magmas at etna at mount etna italy vigorous gas rich eruptions in a d 2001 2002 and 2003 were followed by gas poor eruptions in 2004 2006 and 2007 analyses of volatile co2 h2o s cl f semivolatile cu and involatile nb la elements trapped in olivine hosted melt inclusions from these latest eruptions reveal the effects of the sustained interaction between a percolating gas phase and the stored magma melt inclusion compositions indicate that magmas erupted from 2004 to 2007 were residual from the 2001 2003 eruptions and show significant evolution in the volatile content of the melt these melt inclusion observations and variations in the c s of volcanic gases can be accounted for if melts reequilibrated with co2 rich gases during storage and prior to entrapment as melt inclusions sustained gas percolation caused loss of water and enhancement of co2 in the evolving melt and may strongly influence the behavior of cu which potentially partitions into the gas phase vapor melt interactions during magma storage are important controls on magma evolution at persistently degassing volcanoes

sulfur abundance and its speciation in oxidized alkaline melts abstract the sulfur concentrations and the relative proportions of s2 and s6 were measured by electron microprobe in a series of melt inclusions trapped in phenocrysts from different subduction related and within plate volcanoes the melt inclusions correspond to potassic and shoshonitic primary melts to tholeiitic and hawaiitic primitive melts in the tholeiitic and the transitional basaltic melt inclusions sulfur is mainly present as s2 s 6 s total 0 03 to 0 08 and varies from 0 13 to 0 18 wt the occurrence of immiscible sulfides attests to their saturation in shoshonitic and potassic primary melts sulfur s 0 12 to 0 32 wt is dissolved as both s2 and s6 s 6 s total 0 3 to 0 7 their oxygen fugacity estimated from the s 6 s total ratios ranges from ninio to ninio 1 log unit hawaiitic melts may also dissolve up to 0 3 wt sulfur possibly because of their oxidation state close to ninio as illustrated by samples from mt etna italy variations of sulfur at constant s 6 s total ratio and temperature in both the potassic and shoshonitic primary melts indicate that these melts are undersaturated with respect to a s rich condensed phase in agreement with their relatively high oxidation state it strongly suggests that sulfur behavior in relatively oxidized primary alkaline melts is controlled by the mantle source melting conditions

volatile heavy metal mobility in silicate liquids implications for volcanic degassing and eruption prediction abstract the volatilization of cd re tl pb sb and te from melts in the system cao mgo al 2 o 3 sio 2 cmas and na 2 o mgo al 2 o 3 sio 2 nmas has been investigated at 0 1 mpa and 1200 1350 c experiments were conducted in air using metal doped melts in pt crucibles analysis of quenched glasses by laser ablation inductively coupled plasma mass spectrometry la icp ms normal to the melt gas interface produced concentration profiles for cd re tl pb sb and te to which a semi infinite one dimensional diffusion model could be applied to extract diffusion coefficients d the melt was also doped with cu zn in mo sn and w but concentration profiles for these metals did not develop in the cmas composition at 1300 c the fastest diffusing element was cd having a log d cd 6 5 0 2 the slowest element was re with log d re 7 5 0 3 diffusivities of sb te pb and tl have intermediate values where log d sb 7 1 0 1 log d te 7 2 0 3 log d pb 7 1 0 2 log d tl 7 0 0 2 cm 2 s in the nmas composition log d re 6 5 0 2 log d sb 6 0 0 2 log d pb 6 1 0 1 log d tl 5 8 0 2 cm 2 s values for cd and te were not determined differences in diffusivity of volatile heavy metal ions to a melt gas interface lead to significant fractionation between these metals in magmas during degassing given the observed differences in cd and re diffusivities in the cmas composition we predict an increase in the normalized cd re ratio in the gas phase with increasing bubble growth rate monitoring of the cd re ratios in aerosols from degassing volcanoes may provide a tool for predicting volcanic eruption

measurements of volcanic so2 and co2 fluxes by combined doas multi gas and ftir observations a case study from turrialba and telica volcanoes over the past few decades substantial progress has been made to overcome the technical difficulties of continuously measuring volcanic so2 emissions however measurements of co2 emissions still present many difficulties partly due to the lack of instruments that can directly measure co2 emissions and partly due to its strong atmospheric background in order to overcome these difficulties a commonly taken approach is to combine differential optical absorption spectroscopy doas by using novac scan doas instruments for continuous measurements of crateric so2 emissions and electrochemical ndir multi component gas analyser system multi gas instruments for measuring co2 so2 ratios of excerpts of the volcanic plume this study aims to quantify the representativeness of excerpts of co2 so2 ratios measured by multi gas as a fraction of the whole plume composition by comparison with simultaneously measured co2 so2 ratios using cross crater fourier transform infrared spectroscopy ftir two study cases are presented telica volcano nicaragua with a homogenous plume quiescent degassing from a deep source and ambient temperature and turrialba volcano costa rica which has a non homogeneous plume from three main sources with different compositions and temperatures our comparison shows that in our easier case telica ftir and multi gas co2 so2 ratios agree within a factor about 3 in our complicated case turrialba multi gas and ftir yield co2 so2 ratios differing by approximately 13 25 at most these results suggest that a fair estimation of volcanic co2 emissions can be provided by the combination of doas and multi gas instruments for volcanoes with similar degassing conditions as telica or turrialba based on the results of this comparison we report that by the time our measurements were made telica and turrialba were emitting approximately 100 and 1 000 t day 1 of co2 respectively

ten years of soil co2 continuous monitoring on mt etna exploring the relationship between processes of soil degassing and volcanic activity 1 the measurement of soil co2 flux variations is a well established practice in many volcanic areas around the world until recently however most of these were made using direct sampling methods these days a variety of automatic devices providing real time data now make the continuous monitoring of volcanic areas possible a network of automatic geochemical monitoring stations etnagas network was developed by ingv palermo and installed at various sites on the flanks of mt etna here we present a large set of soil co2 flux data recorded by the network dating back 10 years a period in which several noteworthy eruptive phenomena occurred our statistical analysis strongly suggests that anomalous measurements of soil co2 flux are attributable to volcanic origin and in almost all cases precede volcanic activity here we present the actual data series recorded by etnagas and an interpretative model of the expected behavior of soil co2 flux in terms of increase decrease cycles which corresponded well with the volcanic activity during this period through the use of a comparative approach incorporating both volcanological and geochemical data the global soil co2 flux trends are put into a coherent framework highlighting close links between the time flux variations and volcanic activities these insights made possible from 10 years of uninterrupted data confirm the importance of continuous monitoring of volcanic soil degassing and may contribute in the forecasting of imminent eruptive activity or the temporal evolution of an in progress eruption therefore facilitating civil defense planning in volcanic areas under high hazard conditions

halogen oxide measurements at masaya volcano nicaragua using active long path differential optical absorption spectroscopy active long path differential optical absorption spectroscopy lp doas measurements of halogen oxides were conducted at masaya volcano in nicaragua from april 14 to 26 2007 the active lp doas system allowed night time halogen measurements and reduced the clo detection limit by an order of magnitude when compared to previous passive doas measurements as wavelengths below 300 nm could be used for the doas retrievals bro was detected with an average bro so2 molecular ratio of approximately 3 10 5 during the day however bro values were below the detection limit of the instrument for all night time measurements a strong indication that bro is not directly emitted but rather the result of photochemical formation in the plume itself according to the autocatalytic bromine explosion mechanism despite the increased sensitivity both clo and oclo could not be detected the achieved upper limits for the x so2 ratios were 5 10 3 and 7 10 6 respectively a rough calculation suggests that clo and oclo should be present at similar abundances in volcanic plumes since the doas technique is orders of magnitude more sensitive for oclo than for clo this indicates that oclo should always be detectable in plumes in which clo is found however further lp doas studies are needed to conclusively clarify the role of chlorine oxides in volcanic plumes

spatial domain analysis of carbon dioxide from soils on vulcano island implications for co2 output evaluation abstract the carbon dioxide emissions of volcanoes have been targeted as effective contributors of co 2 to the atmosphere however different sources can be effective and active at the same time in the generation and release of co 2 in volcanic zones since isotopic fingerprinting of co 2 allows the precise identification of different sources coupling carbon isotope and co 2 flux measurements enables the evaluation of the mass contribution of each source to the carbon dioxide emissions this paper accounts for the first extensive spatial analysis of coupled measurements of carbon isotopologues of co 2 in the soil gases and co 2 fluxes discharged by soils on vulcano island an innovative method has been designed tested and fine tuned in the laboratory to measure 13 c co 2 values directly in field using a new type of laser based isotopologues analyzer namely a deltaray thermo fisher scientific the method can be used to determine the carbon isotope composition across the full range of co 2 concentrations in the soil gases 0 100 vol these data have been combined with measurements of the co 2 contents in the soil gases to distinguish co 2 from deep origins from co 2 of biogenic origin in the inhabited area of vulcano porto the method of evaluating the amount of deep origin co 2 in the soil gases is widely applicable in volcanic and geothermal zones for evaluation and monitoring purposes for both gas and volcanic hazards

magma ascent and the pressurization of mount etna s volcanic system after a period of deflation during the 1991 1993 flank eruption mount etna underwent a rapid inflation seismicity and ground deformation show that since 1994 a huge volume of magma intruded beneath the volcano producing from 1998 onward a series of eruptions at the summit and on the flank of the volcano the last of these started on 27 october 2002 is still in progress and can be considered one of the most explosive eruptions of the volcano in recent times here we show how geodetic data and seismic deformation between 1994 and 2001 indicate a radial compression around an axial intrusion consistent with a repressurization of mount etna s plumbing system at a depth of 6 to 15 kilometers which triggered most of the seismicity and provoked the dilatation of the volcano and the recent explosive eruptive activity

the importance of organic rich shales to the geochemical cycles of rhenium and osmium abstract the role that marine organic rich sediments play in the surficial osmium and rhenium cycles has been assumed to be important due to the high re os ratios and high concentrations of these elements in such reducing sediments compared to the average continental crust the high re os leads to rapidly increasing 187os 188os ratios we determine how large a role these sediments play in the surficial osmium and rhenium budgets by compiling a geochemical database to quantify the mean 187re 188os and 187os 188os ratios of organic rich sediments we then utilize estimates of the abundance of organic rich sediments in the geologic record of different ages to estimate an average 187os 188os for these sediments we find that the calculated 187os 188os value of organic rich sediments varies between 2 22 and 2 27 depending on the volume age model used with error estimates of 2 07 to 2 42 and 2 12 to 2 48 respectively despite the fact that these sediments constitute a relatively small proportion of the upper continental crust they contribute a disproportionately large amount 50 to the upper continental crustal rhenium and to a lesser extent 5 10 osmium inventories owing to their high concentrations of these elements

anhydrite stability and the effect of ca on the behavior of sulfur in felsic magmas the distribution of sulfur in the system na2o k2o cao al2o3 sio2 h2o s was investigated at 2 kbar 750 950 c and oxygen fugacities ranging from the co coo to the re reo2 buffer anhydrite caso4 crystallized in all the experiments conducted at oxidizing conditions ni nio 0 5 to 1 and above under otherwise equal conditions an inverse relationship between sulfur and cao concentration was observed in melts coexisting with anhydrite with the solubility product k cao so3 being constant where cao and so3 are the molar fraction of cao and so3 in the quenched glasses this suggests that anhydrite dissociates upon dissolution in the melt according to caso4 anhydrite ca2 melt so42 melt the solubility product strongly depends on temperature with lnk 28 573 917 t 11 26 0 80 this corresponds to an enthalpy of dissolution of h r 237 5 7 6 kj mol under reducing conditions co coo and ni nio buffer cao has no effect on the fluid melt partition coefficient of sulfur d sfluid melt at 850 c 2 kbar partition coefficients were 519 30 at the ni nio buffer and 516 11 at the co coo buffer for cao contents in the melt up to 1 wt these data are virtually identical to those measured in the cao free haplogranite system under reducing conditions however under more oxidizing conditions the fluid melt partition coefficient of sulfur appeared to have increased somewhat in the presence of cao this increase may however also be related to the fact that the final melt compositions in these runs were distinctly peraluminous our data show that calcium has no effect on the degassing of sulfur at reducing conditions but it greatly reduces the amount of sulfur available for rapid degassing under oxidizing conditions by stabilizing anhydrite

ten years of satellite observations reveal highly variable sulphur dioxide emissions at anatahan volcano mariana islands satellite remote sensing enables continuous multiyear observations of volcanic activity in remote settings anatahan mariana islands is a remote volcano in the western north pacific available ground based measurements of sulphur dioxide so2 gas emissions at anatahan place it among thelargest volcanic so2 sources worldwide these ground based measurements however are restricted to eruptive intervals anatahan s activity since 2003 has been dominated temporally by prolonged periods of quiescence using 10 years of satellite observations from omi airs sciamachy and gome 2 we report highly variable so2 emissions within and between eruptive and quiescent intervals at anatahan we find close correspondence between levels of activity reported at the volcano and levels of so2 emissions detected from space eruptive so2 emission rates have a mean value of 6400 t d 1 but frequently are in excess of 20 000 t d 1 conversely so2 emissions during quiescent intervals are below the detection limit of space based sensors and therefore are not likely to exceed 300 t d 1 we show that while anatahan occupies a quiescent state for 85 of the past 10 years only 15 of total so2 emissions over this interval occur during quiescence with the remaining 85 released in short duration but intense syn eruptive degassing we propose that the integration of multiyear satellite data sets and activity histories are a powerful complement to targeted ground based campaign measurements in better describing the long term degassing behavior of remote volcanoes

deep co2 release revealed by stable isotope and diffuse degassing surveys at vulcano aeolian islands in 2015 2018 abstract the partitioning of carbon dioxide co2 released by soils at vulcano island aeolian islands italy was performed by combining the co2 flux and the carbon isotope measurements based on this method the amount of co2 of volcanic origin was quantified six times during the period 2015 2018 the data analysis allowed us to establish the correlation between co2 soil degassing and changes in the contribution of volcanic fluids carbon isotope determinations were performed in situ to enhance the coverage of data collection in space and time these data were combined with both the co2 contents in the ground gases and the soil co2 flux the amount of volcanic co2 was distinguished from that of biogenic origin by implementing a three component mixing model the results of this study indicate that the increase in co2 output in september 2018 reflects the increase in volcanic gas emissions the measurement method and analysis presented in this work are sufficiently general to be applicable to the monitoring programs of active volcanoes

magma transport and storage at mt etna italy a review of geodetic and petrological data for the 2002 03 2004 and 2006 eruptions abstract a detailed reconstruction of magma movements within the plumbing system of mt etna volcano has been made by reviewing the eruptions occurring during the october 2002 december 2006 period the availability of continuous gps data allowed detecting at least ten different ground deformation stages highlighting deflationary and inflationary episodes as well as the occurrence of a shallow dike intrusion these data have been coupled with the available petrological datasets including major trace elements and sr nd pb isotope compositions for the volcanic rocks erupted in the 2002 2006 period we identified two main magmatic reservoirs located at different depths along the plumbing system of the volcano the former is located at a depth of 7 km bsl and fed the 2001 and 2002 03 eruptions while the latter located from 3 5 to 5 5 km bsl fed the 2004 05 and 2006 eruptions petrological characteristics of emitted products have been correlated with the inflation vs deflation cycles related to the identified sources providing evidence for changes through time of the evolutionary degree of the erupted magmas along with variations in their geochemical feature finally we suggest that a modification of the deep plumbing system of the volcano might have occurred during the 2002 03 eruption as a consequence of the major seaward motion of the eastern flank of the volcano