h2 generation in wet grinding of granite and single crystal powders and implications for h2 concentration on active faults 1 granite and single crystals of quartz alkali feldspar biotite and muscovite are ground in ph controlled and pure water solutions using a ball mill at ambient condition to examine the production of h2 the amount of h2 generated by grinding is linearly related with the surface area of ground samples the slope of the straight line indicates h2 productivity of each mineral 3 9 10 3 mol m2 quartz 1 0 10 3 mol m2 alkali feldspar 3 6 10 2 mol m2 biotite 2 2 10 2 mol m2 muscovite 4 5 10 3 mol m2 granite high productivity of biotite and muscovite is probably related to the existence of hydroxyls in their crystal structures interestingly h2 production did not depend on the ph of the solution in the case of biotite and granite while comparisons between fluid acidity and h2 concentration on several active faults suggest that anomalously high h2 is commonly observed at relatively acidic water springs this correlation may be explained by locally high abundance of phyllosilicates

fault controlled soil co2 degassing and shallow magma bodies summit and lower east rift of kilauea volcano hawaii 1997 soil co2 flux measurements were carried out along traverses across mapped faults and eruptive fissures on the summit and the lower east rift zone of kilauea volcano anomalous levels of soil degassing were found for 44 of the tectonic structures and 47 of the eruptive fissures intercepted by the surveyed profiles this result contrasts with what was recently observed on mt etna where most of the surveyed faults were associated with anomalous soil degassing the difference is probably related to the differences in the state of activity at the time when soil gas measurements were made kilauea was erupting whereas mt etna was quiescent although in a pre eruptive stage unlike mt etna flank degassing on kilauea is restricted to the tectonic and volcanic structures directly connected to the magma reservoir feeding the ongoing east rift eruption or in areas of the lower east rift where other shallow likely independent reservoirs are postulated anomalous soil degassing was also found in areas without surface evidence of faults thus suggesting the possibility of previously unknown structures

helium and co2 soil gas emission from santorini greece soil gas investigation is a useful tool to detect active faults the sudden appearance of soil gas anomalies in zones of deep reaching faults represents a promising potential precursor of earthquakes and volcanic eruptions in volcanic areas the development of soil gas monitoring techniques is particularly important as they can represent together with remote sensing techniques the only geochemical methods that can be safely applied during volcanic unrest when it becomes impossible or too dangerous to sample crater fumaroles a soil gas survey was carried out in june 1993 at the main island of thera in the santorini volcanic complex co2 flux and co2 and helium concentrations were measured at 50 cm depth for 76 points covering the entire island with a spacing of 500 m or less several anomalous soil degassing sites have been detected the main anomalies correspond to the kolumbos line and to the kameni line two volcano tectonic fault systems that controlled all the historic volcanic activity of santorini a third anomaly is related to a gas leaking fault cutting the geothermal field of southern thera soil gas data together with geovolcanological and seismological evidence indicate that the kolumbos and kameni lines are the most probable sites for future volcanic or seismic reactivation and provide the basis for the establishment of a new geochemical monitoring technique at thera

soil co2 degassing along tectonic structures of mount etna sicily the pernicana fault abstract carbon dioxide emissions from the soil have been investigated along lines of equally spaced sampling points perpendicular to the pernicana fault on mt etna anomalous values of soil co2 have been found not only along the fault plane but also along directions parallel to it both to the n and to the s of the main fault the acquired data seem to reveal a shallow step like geometry of the pernicana fault system with parallel faults being generally not deeper than the interface between etna s volcanic cover and its sedimentary basement a few hundred meters the distribution of the anomalous co2 emissions has also revealed that the pernicana fault continues at least as far as the ionian sea in an area where only sedimentary rocks crop out this finding would suggest that the main structure is deeper than the base of the volcanic cover thus cutting at least the uppermost portion of etna s sedimentary basement isotopic analyses of c carried out in samples from locations of high co2 seem to indicate that the emitted co2 is a mixture of an organic shallow component and a minor deeper magmatic one both chemical and isotopic data on soil gases emitted in the easternmost part of the studied area distinguished another tectonic structure which seems to be much deeper than the pernicana fault and is roughly directed nne ssw this direction being coincident with an important structural trend of eastern sicily

co2 output and δ13c co2 from mount etna as indicators of degassing of shallow asthenosphere an estimated average co2 output from etna s summit craters in the range of 13 3 mt a has recently been determined from the measured so2 output and measured co2 so2 molar ratios to this amount the co2 output emitted diffusely from the soil 1 mt a and the amount of co2 dissolved in etna s aquifers 0 25 mt a must be added data on the solubility of co2 in etnean magmas at high temperature and pressure allow the volume of magma involved in the release of such an amount of this gas to be estimated this volume of magma 0 7 km3 a is approximately 20 times greater than the volume of magma erupted annually during the period 1971 1995 on the basis of c isotopic data of co2 collected in the etna area and of new hypotheses on the source of mediterranean magmas significant contributions of co2 from non magmatic sources to the total output from etna are unlikely such large outputs of co2 and also of so2 from etna could be due to an anomalously shallow asthenosphere beneath the volcano that allows a continuous escape of gases toward the surface even without migration of magma

spatial and temporal variations of co2 emissions from the active fault zones in the capital area of china abstract the chemical and isotopic composition of 26 soil gas wells and 11 springs along the active fault zones in the capital area of china was determined to investigate the origin of co2 the spatial and temporal variations of co2 emission and their mechanisms the chemical and isotopic data indicated that biogenic co2 was the primary source for co2 from the soil gas wells in both the basin and orogen regions the crust derived and mantle derived co2 could have ascended through the deep cut faults and got into the springs with a few diffusing into the soil gas wells minor air could have intruded into the soil gas wells in the orogen region through the faults cutting the surface owing to the barometric pressure fluctuation relatively high he concentration co2 concentration and flux of soil gas from wells were observed in the basin region than those in the orogen region a significant amount of co2 is produced during the process of oxidation of organic matter in the basin where the organic matter accumulates in thick clayey strata further amounts of co2 are produced by interactions between groundwaters and carbonates which are widely represented in the basin region and by intruded air into the soil gas wells in the orogen region due to barometric pressure fluctuations temporal variations of co2 concentration and co2 flux were observed in soil gas wells in the basin region where seismic activity is more frequent compared to those in the orogen indicating that seismic activity could be responsible for the jumpily temporal variations of co2 concentration and flux in wells monitoring activities of soil gas co2 concentrations and co2 fluxes in active fault zones should be carried out

new perspectives on volcano monitoring in a tropical environment continuous measurements of soil co2 flux at piton de la fournaise la reunion island france detecting renewal of volcanic activity is a challenging task and even more difficult in tropical settings continuous measurements of soil co2 flux were carried out at the piton de la fournaise volcano during 2013 2016 since this site is in the tropics periods of heavy rainfall are in the norm measurements covered volcanic unrest after a hiatus of 3 5 years we find that while temperature has the strongest effect extreme rainfall causes short term noise when corrected and filtered from the environmental influence soil co2 time series permit to detect a major deep magmatic event during march april 2014 three months before the first eruption of the new activity phase correlation with geophysical datasets allow timing of further stages of upward fluid ascent our study validates soil co2 flux monitoring in tropical environments as a valuable tool to monitor magma transfer and to enhance understanding of volcano unrest down to the lithospheric mantle

oxygen fugacity of gases and rocks from momotombo volcano nicaragua application to volcanological monitoring the oxygen fugacity fo2 and the fo2 versus t c relationship of high temperature 600 860 c gas emissions from momotombo volcano nicaragua was determined from both field electrochemical measurements electrolytic cell assembly and thermodynamic computations on gas samples collected between 1978 and 1985 it was then compared with the intrinsic fo2 of fresh and altered lavas from the last eruption 1905 as measured between 500 and 1100 c in laboratory the electrochemical results show that the oxygen fugacity of momotombo fumaroles at equivalent temperature is much higher than that of the fresh 1905 lava fmq buffer and closer to that of their altered wall rocks fmq buffer the equilibrium o2 fugacities calculated from the chemistry of gas samples confirm this pattern however they suggest that the gas mixtures preserve the variable memory of a higher thermal equilibrium achieved at depth under temperature and fo2 conditions of up to 1050 c and 10 9 0 atm respectively which correspond to the cross over between the fo2 t gas and lava trends these data thus support the idea that momotombo volcanic gases released in a period of increasing activity escape from a shallow magma body before suffering a variable oxidation during their ascent through both unbuffered cooling and reactions with environmental fluids and rocks this late oxidation is weaker at central fumaroles than at peripherical ones while between 1978 and 1985 the temperature of the hottest fumarole increased from 750 to 865 900 c the equilibrium fo2 of the gas decreased by nearly one order of magnitude at comparable equilibrium temperature such an evolution presumably reflects an increasing connection between the surface exhalations and the magma degassing at depth along with time this work underlines the possibility of monitoring the processes of magma ascent and gas magma separation within a volcano before an eruption by continuously recording the changes of both oxygen fugacity and temperature in hot fumaroles

precursory diffuse carbon dioxide degassing signature related to a 5 1 magnitude earthquake in el salvador central america abstract anomalous changes in the diffuse emission of carbon dioxide have been observed before some of the aftershocks of the 13 february 2001 el salvador earthquake magnitude 6 6 a significant increase in soil co 2 efflux was detected 8 days before a 5 1 magnitude earthquake on 8 may 2001 25 km away from the observation site in addition pre and co seismic co 2 efflux variations have also been observed related to the onset of a seismic swarm beneath san vicente volcano on may 2001 strain changes and or fluid pressure fluctuations prior to earthquakes in the crust are hypothesized to be responsible for the observed variations in gas efflux at the surface environment of san vicente volcano

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

soil and fumarole gases of mount etna geochemistry and relations with volcanic activity abstract between 1993 and 1996 gas samples were collected on mt etna volcano from both high and low temperature fumaroles and from soils in areas of anomalous degassing located on the flanks of the volcanic edifice the chemical composition of all the emitted gases is consistent with their magmatic origin during their transport to the surface they would undergo shallow mixing processes mostly with air locally as in the case of a point in the lower southwestern flank of the volcano p39 very high contents of he and ch4 indicate that deep gases mainly interact with ground waters and also with a hydrocarbon reservoir the isotopic composition of carbon in co2 from these gases also suggests its primary magmatic origin with inferred 13 c values of magmatic co2 in the range 2 to 1 vs pdb such values significantly more positive than those measured in morbs are in the typical range measured at the other mediterranean volcanoes 5 to 0 more negative values can be explained by shallow interactions between magmatic and organic co2 and or between the former and cold t 120 c ground waters both chemical and isotopic gas geothermometers agree in indicating calculated temperatures ranging from 180 to 270 c for the soil gases collected from low temperature fumaroles near the summit and temperatures around 150 c for the cold gases from p39 thus confirming the presence of a hydrothermal aquifer beneath this point a chemical geothermometer applied on the gases collected from the high temperature fumaroles near the summit craters shows equilibrium temperatures ranging from 385 to 690 c lastly many of the studied parameters showed anomalous variations in time during the studied period the most important of these concerned the flux of co2 through the soil and the concentration of soil h2 which were closely correlated with strong increases in the volcanic activity of etna

anomalous hydrogen emissions from the san andreas fault observed at the cienega winery central california we began continuous monitoring of h2 concentration in soil along the san andreas and calaveras faults in central california in december 1980 using small h2 o2 fuel cell sensors ten monitoring stations deployed to date have shown that anomalous h2 emissions take place occasionally in addition to diurnal changes among the ten sites the cienega winery site has produced data that are characterized by very small diurnal changes a stable baseline and remarkably distinct spike like h2 anomalies since its installation in july 1982 a major peak appeared on 1 10 november 1982 and another on 3 april 1983 and a medium peak on 1 november 1983 the occurrences of these peaks coincided with periods of very low seismicity within a radius of 50 km from the site in order to methodically assess how these peaks are related to earthquakes three h2 degassing models were examined a plausible correlational pattern was obtained by using a model that 1 adopts a hemicircular spreading pattern of h2 along an incipient fracture plane from the hypocenter of an earthquake 2 relies on the feo h2o reaction for h2 generation and 3 relates the accumulated amount of h2 to the mass of serpentinization of underlying ophiolitic rocks the mass was tentatively assumed to be proportional to the seismic energy of the earthquake

infrasonic evidences for branched conduit dynamics at mt etna volcano italy an edited version of this paper was published by agu copyright 2009 american geophysical union

review of the evolution of geochemical monitoring networks and methodologies applied to the volcanoes of the aeolian arc italy abstract fluids discharged from volcanic systems are the direct surface manifestation of magma degassing at depth and provide primary insights for evaluating the state of volcanic activity we review the geochemical best practice in volcanic surveillance based to a huge amount of monitoring data collected at different active volcanoes using both continuous and discontinuous approaches the targeted volcanoes belong to the aeolian arc located in the tyrrhenian sea italy and they have exhibited different activity states during the monitoring activities reported here la fossa cone on vulcano island has been in an uninterrupted quiescent stage characterized by variable solfataric activity in contrast stromboli island has shown a persistent mild explosive activity episodically interrupted by effusive eruptions in 1985 2002 2007 and 2014 panarea island which is the summit of a seamount rising from the seafloor of the southern tyrrhenian sea showed only undersea fluid release the only observable clues of active volcanism at panarea island have been impulsive changes in the undersea fluid release with the last submarine gas burst event being observed in november 2002 the geochemical monitoring and observations at each of these volcanoes has directly involved the volcanic plume and or the fumarole vents thermal waters and diffuse soil degassing depending on the type of manifestations and the level of activity encountered through direct access to the magmatic samples when possible and the collection of as much observable data related to the fluid release as possible the aim has been i to verify the thermodynamic equilibrium condition ii to discern among the possible hydrothermal magmatic marine and meteoric sources in the fluid mixtures iii to develop models of the fluid circulation supported by data iv to follow the evolution of these natural systems by long term monitoring and v to support surveillance actions related to defining the volcanic risk and the evaluation and possible mitigation of related hazards the examples provided in this review article show the close relationships among data analysis interpretation and modeling we particularly focus on describing the fieldwork procedures since any theoretical approach must always be verified and supported by field data rather than just by experiments controlled in laboratory indeed the natural systems involve many variables producing effects that cannot be neglected the monitored volcanic systems have been regarded as natural laboratories and all of the activities have focused on both volcanological research and surveillance purposes in order to ensure that these two goals have overlapped an appendix is also included that explains the scientific approach to the systematic activities regarding geochemical monitoring of volcanic activity

statistical analysis reveals spatial and temporal anomalies of soil co2 efflux on mount etna volcano italy abstract extensive geochemical surveys were carried out on the western flank of mt etna volcano for the determination of soil co 2 effluxes in order to study the relationship between soil gas anomalies faults and volcanic activity the areas of santa maria di licodia sml and w rift wr were selected because of their importance within the volcano tectonic framework of etna two gas surveys were performed in each area in different periods november 2005 and may 2006 in sml september 2007 and june 2008 in wr with 2140 measurements in total in each survey data were log normally distributed and were statistically different from the other surveys therefore their standard normal form was used to compare them log probability plots revealed five populations of data in each survey due to varying degrees of mixing between biogenic and magmatic co 2 and indicated anomalous co 2 effluxes for values 36 g m 2 d 1 magmatic output was 39 2 t d 1 in november 2005 15 8 t d 1 in may 2006 98 4 t d 1 in september 2007 and 234 1 t d 1 in june 2008 natural neighbor interpolation of standardized data produced distribution maps that showed some clustering of anomalous values along directions possibly related to hidden faults compatible with volcanic or regional structural trends analysis of magmatic co 2 emissions in time suggested a possible influence from seasonal variations but comparison with volcanic activity of etna also indicated a volcanic influence accompanying the 2008 2009 flank eruption

changes in heat released by hydrothermal circulation monitored during an eruptive cycle at mt etna italy the shallow vertical temperature profile has been measured in the proximity of an eruptive fissure far about 4 km north northeast from mt etna central craters the monitoring site was a steam heated soil lying between a group of flank fractures on the upper northeast flank of mt etna italy i e on the northeast rift we chose this area because it was close to an eruptive fissure that opened in 2002 and extended from about 2500 to about 1500 m a s l with our aim being to determine a connection between this fracture system and the ongoing volcanic activity heat flux anomalies from the ground from september 2009 to september 2012 were evaluated changes in the hydrothermal release which can be related to variations in volcanic activity are discussed and compared to the published geophysical data the heat flux ranges varied during the pre eruptive from about 7 to 38 w m 2 syn eruptive from about 3 to 49 w m 2 and post eruptive phases with the heat released being lowest at the latter phase from about 1 to 20 w m 2 moreover the heat flux time variation was strongly correlated with the eruption rate from the new southeast crater between january 2011 and april 2012 the migration of magma through active conduits acts as a changing heating source for steam heated soils located above the active fractures our findings suggest that tracking the heat flux above active fractures constitutes a useful investigation field for low cost thermal monitoring of volcanic activity time variations in their emissions could highlight the relationship between a hydrothermal circuit and the local network of fractures possibly indicating variation in the structural weakness of a volcanic edifice continuous monitoring of heat flux combined with a realistic model would contribute to multidisciplinary investigations aimed at evaluating changes in volcano dynamics

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

role of local wind circulation in plume monitoring at mt etna volcano sicily insights from a mesoscale numerical model 1 mesoscale simulations at mt etna volcano sicily italy validated by measurements highlight the fundamental role played by the local wind field in the dispersion of a gaseous volcanic plume during the night downslope surface winds over hill flow and katabatic breezes force the plume to follow the steep morphology whereas during the day very frequent nnw synoptic winds crash into the cone and are contrasted by se strong sea breezes and anabatic winds with the consequent formation of convective ascendant currents the local mesoscale wind reconstruction can provide useful improvements in gaseous flux estimation far away synoptic wind velocities often used in these flux evaluations might be inadequate we propose a 3d numerical mesoscale wind reconstruction to evaluate plume dynamics and from it plume flux and potential hazard throughout all the hours of the day

geochemical challenge to earthquake prediction the current status of geochemical and groundwater observations for earthquake prediction in japan is described the development of the observations is discussed in relation to the progress of the earthquake prediction program in japan three major findings obtained from our recent studies are outlined i long term radon observation data over 18 years at the ske suikoen well indicate that the anomalous radon change before the 1978 izu oshima kinkai earthquake can with high probability be attributed to precursory changes ii it is proposed that certain sensitive wells exist which have the potential to detect precursory changes iii the appearance and nonappearance of coseismic radon drops at the ksm kashima well reflect changes in the regional stress state of an observation area in addition some preliminary results of chemical changes of groundwater prior to the 1995 kobe hyogo ken nanbu earthquake are presented

rapidly accelerating subsidence in the greater vancouver region from two decades of ers envisat radarsat 2 dinsar measurements abstract rapidly accelerating ground subsidence in the south western part of british columbia the third largest metropolitan area in canada with over 2 3 million of inhabitants is estimated using the multidimensional small baseline subset msbas advanced differential interferometric synthetic aperture radar dinsar an effective processing strategy for multi mission multi temporal sar data the synthetic aperture radar sar data used in this study consists of seven independent data sets one ascending and one descending ers 1 2 and envisat frames together spanning july 1995 september 2010 and three radarsat 2 frames spanning february 2009 october 2012 during the july 1995 october 2012 period we observe fast ground subsidence with a maximum rate of about 2 cm year in the greater vancouver region that includes the fraser river delta and the cities of burnaby richmond surrey new westminster and vancouver the rapidly accelerating subsidence is observed beneath the vancouver international airport skytrain terminal as well as several agricultural and industrial locales these time series suggest that the subsidence rate at the studied regions does not decrease with time as suggested in previous studies but remains steady or increases these results also demonstrate the importance of acquiring and appropriately estimating longer time series as previous studies on the same greater vancouver area may have misinterpreted the long term ground deformation rate and direction and underestimated the potential hazard the long term impact of this subsidence on urban infrastructure can be significant and needs to be investigated further

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

origin of hydrogen and carbon dioxide in fault gases and its relation to fault activity gases occluded in fracture zones of active faults are characterized by a high concentration of h 2 and or co 2 a predominant gas species h 2 or co 2 is related to the lithofacies which the fault cuts carbon dioxide concentration in sediments fluctuates with temperature this evidence and sigma 13 c of co 2 about 20 suggests that co 2 originates from organic materials carbon dioxide with sigma 13 c of 5 to 17 in brecciated gneiss containing marble may have been produced by interaction between organically derived co 2 and the marble or alternatively may have been magmatically derived hydrogen usually occurs in sheared silicate rocks and its concentration fluctuates a great deal the concentration of h 2 from active faults associated with historical earthquakes usually amounts to as high as several percent in maximum whereas the concentration of h 2 from quaternary faults not associated with historical earthquakes is at most 1

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

discharge of h2 from the atotsugawa and ushikubi faults japan and its relation to earthquakes the concentration of h2 in soil gases has been measured weekly at five stations on the atotsugawa and ushikubi faults in northern central main island japan since 1981 in search of possible relationship with earthquakes the observed h2 concentration varies from lower than 1 ppm to 7 8 in time and place when a large earthquake m 7 7 epicenter distance 486 km occurred on 26 may 1983 an outstanding discharge of h2 was observed at all five stations preseismically at three of them and coseismically at the other two simultaneous h2 emission was also observed at some stations in seven other occasions these periods of unusual h2 discharge nearly coincided with occurrences of major earthquakes in japan but not of local minor earthquakes along the atotsugawa fault this fault being a deep fracture zone may be sensitive to large scale crustal stress changes which incidentally cause the major earthquakes increased h2 may be produced by rock fracture caused by the increased stresses on the fault and by the earthquakes themselves local minor earthquakes along atotsugawa fault with magnitude lower than 3 may be unable to cause sufficient rock fracture to produce significant h2

sensing the ups and downs of las vegas insar reveals structural control of land subsidence and aquifer system deformation land subsidence in las vegas nevada united states between april 1992 and december 1997 was measured using spaceborne interferometric synthetic aperture radar the detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures faults and sediment composition clay thickness the maximum detected subsidence during the 5 75 yr period is 19 cm comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground water levels brought about by a net reduction in ground water extraction temporal analysis also detects seasonal subsidence and uplift patterns which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability

the evolution of aqueous vapor from silicate melts effect on oxygen fugacity abstract the simplest possible aqueous vapor evolved from an iron bearing magma under normal conditions is an h 2 o h 2 mixture hydrogen is produced by the oxidation of fe ii to fe iii by water in the magma yielding an increase in f o 2 equations are derived which model this mass transfer process the resulting differential equation expresses the change in magmatic f o 2 as a function of a change in n 1 h 2 o the vapor evolution progress variable the calculations demonstrate that in this simple scheme very iron poor magmas h 2 o feo are required to produce significant increases in magmatic f o 2 the incremental increase in o 2 during vapor evolution becomes progressively smaller as o 2 increases with this process becoming highly inefficient as the hematite stability field is approached other more complete processes involving meteoric water assimilation of altered rocks and subsolidus processes may produce the observed increase in f o 2 inferred to have occurred in systems of normal iron contents in low iron systems such as the high silica rhyolitic magmas associated with climax type porphyry molybdenum systems high oxygen fugacities may be obtained by this mechanism

measurements of 220rn and 222rn and co2 emissions in soil and fumarole gases on mt etna volcano italy implications for gas transport and shallow ground fracture this work was funded by the istituto nazionale di geofisica e vulcanologia s g m n and by the dipartimento per la protezione civile italy projects v3 6 28 etna m n and v5 08 diffuse degassing in italy s g and nsf ear 063824101 k w w s

soil co2 degassing on mt etna sicily during the period 1989 1993 discrimination between climatic and volcanic influences wide variations were measured in the diffuse co2 flux through the soils in three selected areas of mt etna between august 1989 and march 1993 degassing of co2 from the area of zafferana etnea s venerina on the eastern slope of the volcano has been determined to be more strongly influenced by meteorological parameters than the other areas the seasonal component found in the data from this area has been excluded using a filtering algorithm based on the best fitting equation calculated from the correlation between co2 flux values and those of air temperature the filtered data appear to have variations temporally coincident with those from the other areas thus suggesting a common and probably deep source of gas the highest fluxes measured in the two most peripheral areas may correlate well with other geophysical and volcanological anomalous signals that preceded the strong eruption of 1991 1993 and that were interpreted as deep pressure increases anomalous decreases in co2 fluxes accompanied the onset and the evolution of that eruption and have been interpreted as a sign of upward migration of the gas source the variations of co2 flux at the 1989 se fracture have also given interesting information on the timing of the magmatic intrusion that has then fed the 1991 1993 eruption

runoff generation in a sandy area the nizzana sands western negev israel this paper presents the results of sprinkling experiments conducted over the lower part of vegetated and crusted linear dunes as well as over flat playa surfaces that appear in the interdune corridors data obtained show that these two surface units respond quickly to rainstorms runoff generation can be expected for any storm exceeding 2 3 mm and runoff coefficients are high when the topsoil algal crust 1 to 2 mm thick is removed from the surface of the dune infiltration increases drastically and eliminates any possibility of runoff generation under present day rainfall conditions this data may be of great help in the understanding of the geomorphology and sedimentary sequence of the corridors separting linear dunes

diffuse co2 soil degassing and co2 and h2s concentrations in air and related hazards at vulcano island aeolian arc italy ingv dpc programme project v5 diffuse degassing in italy airplane firb project of the italian ministry of the university and research

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

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

anomalous surface heave induced by enhanced oil recovery in northern alberta insar observations and numerical modeling recent interferometric synthetic aperture radar observations over northern alberta canada show persistent surface heave occurring at rates of 1 4 cm yr localized at sites where the steam assisted gravity drainage technique is currently used to extract bitumen from the athabasca oil sands we find that uplift rates above the horizontal injector wells are strongly correlated with rates of steam injection even though there is a net fluid loss from the reservoir pore space as oil and water are withdrawn through the production wells in combination with available steam injection and bitumen production data at four sites we use reservoir flow models to explain how the thermal and geomechanical effects of steam injection on an oil sand reservoir can generate uplift at the surface results of our numerical experiments show that persistent surface heave consistent with observed rates can be driven by stress changes in the reservoir due to porous flow and thermal expansion we also observe an unexpected localized uplift of magnitude equal to or greater than the heave above the sites of steaming but located at clusters of wellheads which are outside the region of influence of the steam chambers we show that this wellhead deformation can be explained by thermal expansion of rock near the injector wells

patterns in the recent 2007 2008 activity of mount etna volcano investigated by integrated geophysical and geochemical observations 1 seismic deformation and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment in spite of their wide use there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques here we combine seismic volcanic tremor and long period seismicity deformation gps and geochemical volcanic gas plume co2 so2 ratios measurements in an attempt to interpret trends in the recent 2007 2008 activity of etna volcano we show that each eruptive episode occurring at the southeast crater sec was preceded by a cyclic phase of increase decrease of plume co2 so2 ratios and by inflation of the volcano s summit captured by the gps network these observations are interpreted as reflecting the persistent supply of co2 rich gas bubbles and eventually more primitive magmas to a shallow depth of 1 2 8 km asl magma storage zone below the volcano s central craters ccs overpressuring of the resident magma stored in the upper ccs conduit triggers further magma ascent and finally eruption at sec a process which we capture as an abrupt increase in tremor amplitude an upward 2800 m asl and eastward migration of the source location of seismic tremor and a rapid contraction of the volcano s summit resumption of volcanic activity at sec was also systematically anticipated by declining plume co2 so2 ratios consistent with magma degassing being diverted from the central conduit area toward sec

soil gases in geothermal prospecting two case histories sabatini volcanoes and alban hills latium central italy studies were conducted to test the effectiveness of soil gas surveying for locating permeable zones in buried carbonate reservoirs and to locate the presence of possible gasoeus haloes linked to active geothermal systems two surveys were conducted in the sabatini volcanoes and alban hills areas each area is characterized by a thermal anomaly and a scarcity of surface manifestations in the former area co2 h2 he and ch4 in soil gases were determined in the latter total helium in about 1000 soil gas samples and in about 400 water samples was determined in both cases anomalous concentrations of the gases were found mainly according to fault or fracture systems therefore it seems possible to utilize the distribution of the gases in these zones as indicators of deep permeability

advances in soil gas geochemical exploration for natural resources some current examples and practices field studies have demonstrated that gas anomalies are found over buried mineral deposits abnormally high concentrations of sulfur gases and carbon dioxide and abnormally low concentrations of oxygen are commonly found over sulfide ore deposits helium anomalies are commonly associated with uranium deposits and geothermal areas helium and hydrocarbon gas anomalies have been detected over oil and gas deposits gases are sampled by extracting them from the pore space of soil by degassing soil or rock or by adsorbing them on artificial collectors the two most widely used techniques for gas analysis are gas chromatography and mass spectrometry the detection of gas anomalies at or near the surface may be an effective method to locate buried mineral deposits

soil gas emanations as precursory indicators of volcanic eruptions field measurements conducted on several active volcanoes in italy the lesser antilles and indonesia demonstrate the common occurrence of diffuse soil gas emanations from the volcanic piles at distances from active craters or fumarolic zones these emanations consist essentially of carbon dioxide and rare gases and their genetic link with crater fumaroles and or magma degassing at depth can be verified both chemically and isotopically we emphasize here the potential use of these fluids for continuous volcano monitoring and eruption forecasting

monitoring of fumarole discharge during the 1975 1982 rifting in krafla volcanic center north iceland abstract fumarole discharge chemistry in the krafla geothermal field changed regionally during the 1975 1982 rifting activity the discharge chemistry previously encountered in the krafla fumarole grounds was masked by a carbon dioxide rich gas during the first weeks of rifting the new discharge composition remained unchanged until 1983 when the first signs of recovery of the previous equilibrium composition appeared at the margins of the area the outgassing carbon dioxide is released from the deep aquifers beneath the area by the interaction of magmatic gas with the hydrothermal system in addition to juvenile magmatic carbon the outgassing contains carbon released from the hydrothermal systed upon reaction with acid magmatic gases increased boiling of the hydrothermal fumaroles was induced by the lowering of the partial pressure of steam due to increased gas content in the fumarole conduits at the center of rifting activity above the magma chamber the fumarole discharge was temporarily mixed with magmatic gases during local effusive activity hydrogen was the dominating magmatic gas in that discharge due to the preferred degassing of hydrogen from magma at shallow levels these hydrogen pulses increased in magnitude and duration towards the end of rifting in 1982 the discharge chemistry correlates with the expansion of the magma reservoir of the volcano regional change of long duration and local volcanism short lived change hydrogen pulses the chemical monitoring of fumaroles in krafla shows that the chemical surveillance of volcanos needs rapid methods for sampling and complete chemical analysis which can be interpreted in terms of reactions and magmatic processes

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