carbon dioxide and carbon monoxide emission rates from an alkaline intra plate volcano mt erebus antarctica abstract this is the first report of co and co 2 flux from mt erebus antarctica an alkaline intra plate volcano with a convecting lava lake the co 2 flux from the mt erebus plume was measured by in plume infrared analysis during december 1997 december 1999 and january 2001 the co 2 emission rates were consistently close to the average of 22 3 kg s 1930 mg day for the three measurements conducted over a 4 year period even though the third measurement january 2001 was conducted at a time of elevated activity as co 2 is considered a good indicator of eruptive activity a more frequent type of monitoring system may be necessary to detect changes related to activity at mt erebus increased co 2 emissions lost via strombolian eruptions in the lava lake were not accounted for in our airborne measurements carbon monoxide flux determined by fourier transform infrared spectroscopy in december 1995 yielded a rate of 1 74 kg s 150 mg day and a high co co 2 ratio of 0 12

a geochemical and geophysical reappraisal to the significance of the recent unrest at campi flegrei caldera southern italy volcanic unrest at calderas involve complex interaction between magma hydrothermal fluids and crustal stress and strain campi flegrei caldera cfc located in the naples italy area and characterised by the highest volcanic risk on earth for the extreme urbanisation undergoes unrest phenomena involving several meters of uplift and intense shallow micro seismicity since several decades despite unrest episodes display in the last decade only moderate ground deformation and seismicity current interpretations of geochemical data point to a highly pressurized hydrothermal system we show that at cfc the usual assumption of vapour liquid coexistence in the fumarole plumes leads to largely overestimated hydrothermal pressures and accordingly interpretations of elevated unrest by relaxing unconstrained geochemical assumptions we infer an alternative model yielding better agreement between geophysical and geochemical observations the model reconciles discrepancies between what observed 1 for two decades since the 1982 84 large unrest when shallow magma was supplying heat and fluids to the hydrothermal system and 2 in the last decade compared to the 1980 s unrest the post 2005 phenomena are characterized by much lower aquifers overpressure and magmatic involvement as indicated by geophysical data and despite large changes in geochemical indicators our interpretation points out a model in which shallow sills intruded during 1969 1984 have completely cooled so that fumarole emissions are affected now by deeper co2 richer magmatic gases producing the modest heating and overpressure of the hydrothermal system our results have important implications on the short term eruption hazard assessment and on the best strategies for monitoring and interpreting geochemical data this article is protected by copyright all rights reserved

diffuse volcanic gas emission and thermal energy release from the summit crater of pico do fogo cape verde we report the first detailed study of diffuse emission of carbon dioxide co2 hydrogen sulfide h2s helium he and hydrogen h2 from the summit crater of pico do fogo volcano cape verde diffuse co2 h2s he and h2 gas fluxes were measured at 57 sampling sites and ranged up to 12 800 13 1 and 6 g m 2 day 1 respectively soil temperature measurements at each sampling site were used to evaluate the heat flux most of the summit crater shows relatively high co2 efflux with highest values close to the fumarolic area suggesting a structural control of the degassing process in contrast h2s effluxes were negligible or very low at the summit crater except close to the fumarolic area where anomalously high co2 efflux and soil temperatures were also measured we estimate total co2 h2s he and h2 diffuse gas fluxes of 219 t day 1 25 4 and 33 kg day 1 respectively based on a h2o co2 mass ratio of 1 52 measured at the fumaroles we estimate a diffuse steam flux from the summit crater of approximately 330 t day 1 the enthalpy of this steam is equivalent to a heat flux of about 10 3 mw the diffuse gas emission and thermal energy released from the summit crater of pico do fogo volcano are comparable to those observed at other volcanoes sustained surveillance of pico do fogo using these methods will be valuable for monitoring the activity of one of the most active volcanoes in the atlantic ocean

first characterization of gamkonora gas emission north maluku east indonesia gamkonora is an active volcano capable of intense manifestations that regularly forced thousands of inhabitants to flee their villages the most extreme eruption in 1673 was a vei 5 event that induced pitch dark environment over the region paradoxically little is known about gamkonora volcano and here we present the first gas measurement results obtained in september 2018 using a multigas and a scanning doas results highlight a relatively small but magmatic gas with a co2 st of 3 5 in the range of high temperature gas emissions from indonesian volcanoes and h2o so2 co2 so2 h2s so2 and h2 so2 ratios of 135 5 6 0 6 and 0 2 respectively the daily gas emission budget corresponds to 129 t 13 t 3 4 t 1 1 t and 0 03 t for h2o co2 so2 h2s and h2 respectively bulk rock analyses indicate a basaltic andesite to andesite source beneath gamkonora

sustaining persistent lava lakes observations from high resolution gas measurements at villarrica volcano chile active lava lakes as the exposed upper part of magmatic columns are prime locations to investigate the conduit flow processes operating at active degassing volcanoes persistent lava lakes require a constant influx of heat to sustain a molten state at the earth s surface several mechanisms have been proposed to explain how such heat transfer can operate efficiently these models make contrasting predictions with respect to the flow dynamics in volcanic conduits and should result in dissimilar volatile emissions at the surface here we look at high frequency so2 fluxes plume composition thermal emissions and aerial video footage from the villarrica lava lake in order to determine the mechanism sustaining its activity we found that while fluctuations are apparent in all datasets none shows a stable periodic behaviour these observations suggest a continuous influx of volatiles and magma to the villarrica lava lake we suggest that ascending volatile rich and descending degassed magmas are efficiently mixed within the volcanic conduit resulting in no clear periodic oscillations in the plume composition and flux we compare our findings to those of other lava lakes where equivalent gas emission time series have been acquired and suggest that gas flux magma viscosity and conduit geometry are key parameters determining which flow mechanism operates in a given volcanic conduit the range of conduit flow regimes inferred from the few studied lava lakes gives a glimpse of the potentially wide spectrum of conduit flow dynamics operating at active volcanoes

the statistical eigenvector analysis technique seat for dip data analysis abstract dip data acquired from image logs i e the dip azimuth of planar features are extensively used in the oil and gas industry to assist in interpreting subsurface geology gradual and or abrupt variations in dip data with depth may indicate different structural features e g faults folds etc or changes to sedimentary systems e g unconformity the statistical eigenvector analysis technique seat and accompanying computer application are useful in statistically calculating the orientation and geometry of subsurface structures from dip data poles to planes on a spherical projection over a given depth interval may reveal cluster or girdle distributions which can be interactively analyzed using statistical distribution functions on the unit sphere seat provides a mathematical solution for as few as two data points and has the potential to be applied to dip data at the meter scale the orientation and geometry of various subsurface geological features e g folds fault drag deformation etc can be interactively calculated over a chosen depth interval seat is applied to a dip dataset acquired from a modern 8 padded electronic borehole image log and a previously studied dipmeter data from the discovery well of the railroad gap field to illustrate its higher accuracy in determining the orientation and geometry of subsurface structures compared to older methods seat allows for a vastly improved interpretation of subsurface geological features when combined with high resolution borehole image logs and accurate dip data improved understanding of subsurface geometries may allow for better business decisions in future exploration and appraisal of existing assets

models to interpret bedform geometries from cross bed data in order to understand better the relation of cross bed azimuth distributions to bedforms geometric models were developed for migrating bedforms using a minimum number of parameters semi elliptical and sinusoidal bedform crestlines were modeled with curvature and sinuosity as parameters both bedform crestlines are propagated at various angles of migration over a finite area of deposition two computational approaches are used a statistical random sampling monte carlo technique over the area of the deposit and an analytical method based on topology and differential geometry the resulting foreset azimuth distributions provide a catalogue for a variety of situations the resulting thickness distributions have a simple shape and can be combined with the azimuth distributions to constrain further the cross strata geometry paleocurrent directions obtained by these models can differ substantially from other methods especially for obliquely migrating low curvature bedforms interpretation of foreset azi

magmatic gas percolation through the old lava dome of el misti volcano the proximity of the major city of arequipa to el misti has focused attention on the hazards posed by the active volcano since its last major eruption in the fifteenth century el misti has experienced a series of modest phreatic eruptions and fluctuating fumarolic activity here we present the first measurements of the compositions of gas emitted from the lava dome in the summit crater the gas composition is found to be fairly dry with a h2o so2 molar ratio of 32 3 a co2 so2 molar ratio of 2 7 0 2 a h2s so2 molar ratio of 0 23 0 02 and a h2 so2 molar ratio of 0 012 0 002 this magmatic gas signature with minimal evidence of hydrothermal or wall rock interaction points to a shallow magma source that is efficiently outgassing through a permeable conduit and lava dome field and satellite observations show no evolution of the lava dome over the last decade indicating sustained outgassing through an established fracture network this stability could be disrupted if dome permeability were to be reduced by annealing or occlusion of outgassing pathways continued monitoring of gas composition and flux at el misti will be essential to determine the evolution of hazard potential at this dangerous volcano

first gas and thermal measurements at the frequently erupting gamalama volcano indonesia reveal a hydrothermally dominated magmatic system abstract the first gas and thermal measurements at the summit of the gamalama volcano indicate that the system is dominated by hydrothermal processes this is highlighted by the prevalence of h2s over so2 h2s so2 2 8 a high co2 so2 ratio 76 201 and a low heat transfer 3 0 mw to the surface a relative variation in gas composition is observed along the degassing fracture zone possibly due to partial s scrubbing despite this surface hydrothermal signature the system exhibits high gas equilibrium temperatures 425 480 c indicating that fluids are not exclusively derived from a boiling hydrothermal aquifer but also sourced by cooling and crystallizing basaltic magma at deep that continues to inject magmatic fluids into the system this hydrothermally dominated activity on gamalama possibly persisted over the last two decades during which a high number of eruptive events were witnessed the period coincides with the opening of large fractures at the summit that subsequently shifted the volcanic activity from the crater center to the peripheral fractures zones these fractures that possibly developed in response to the regional geodynamics have weakened the hydrothermal seal allowing the pressure developed by the hydrothermal magmatic system and promoted by the high annual rainfall to rapidly exceeds the tensile strength of the seal leading to the numerous phreatic eruptions

remote determinations on fumarole outlet temperatures in an eruptive volcano direct measurement of the fumarole outlet temperature in active volcanoes is impractical therefore we used an aircraft to sample h2 in the volcanic plume ejected from sakurajima volcano to remotely estimate the highest fumarolic temperatures of the volcano based on hydrogen isotopic fractionation between h2 and magmatic h2o we successfully estimated that the d of the fumarolic h2 in september and december 2014 was 135 13 and 113 11 respectively and that the corresponding highest outlet temperatures were 1050 120 c and 1199 139 c although the temperatures were higher than those determined by using infrared remote sensing we concluded that they are more reliable estimates of the highest fumarole outlet temperatures combined with plume sampling by using aircraft remote temperature sensing based on the d of h2 in volcanic plumes can be widely applied to active volcanoes to determine the highest fumarole outlet temperatures

high resolution sequence stratigraphy of fluvio deltaic systems prospects of system wide chronostratigraphic correlation a basin scale numerical model with a sub grid parameterization of fluvio deltaic processes and stratigraphy was used to study the relation between alluvial sedimentation and marine deltaic deposition under conditions of time invariant forcing the experiments show that delta evolution is governed by a robust morphodynamic feedback loop which provides a link between major avulsions delta lobe switches and sequestration of sediments on the delta plain major avulsions driven by local superelevation result in abandonment of delta lobes and initiation of new lobes progradation of the delta front lengthens the fluvial profile and reduces its gradient which induces aggradation upstream the aggradation in turn causes local superelevation of the channel belt each major avulsion causes a wave of incision to migrate upstream whereas downstream of the avulsion point the rate of aggradation temporarily increases until a new equilibrium situation has been established the feedback loop explains storage and release of fluvial sediments without the need to invoke changes in upstream or downstream controls and provides a plausible mechanism for the generation of high frequency incision aggradation cycles as the sole result of compensational stacking the stratigraphic expression of a depocentre shift is an essentially isochronous surface hence the stratigraphic record of fluvio deltaic systems may be subdivided into a series of units representing intervals during which a channel belt and delta lobe were forming at a fixed location in the basin so called chronosomes fluvio deltaic chronosomes are bounded by abandonment surfaces which are clearly expressed in the marine as well as the fluvial domain the surface marking the abandonment of a particular channel belt and delta lobe correlates with the surface at the base of a new delta lobe landward this surface forms the base of an aggradational package of fluvial sediments downstream of an avulsion site associated with a lobe switch upstream of this site the conformable surface passes into a surface of fluvial incision and terrace formation onlapped by aggradational channel belt deposits identification of the isochronous bounding surfaces of chronosomes in the field offers the attractive prospect of high resolution chronostratigraphic correlation throughout fluvio deltaic systems

trackdip a multi scale processing of dipmeter data method tests and field example for 3 d description of gravity driven deformations in the eocene foreland basin of ainsa spain abstract this paper presents trackdip a new method for dipmeter data processing this method selects localizes and measures significant tilts from the comparison at various scales of the changes of orientation of sedimentary beddings we tested this method on simple cases unconformity gradual tilt successive tilts without and with additional random noise and on a field example along three sections in the eocene sobrarbe delta ainsa foreland basin northern spain for synthetic data sets the method clearly identifies and measures the introduced tilts on the field sedimentary and tectonic structures especially three main syn sedimentary sliding surfaces s1 s3 were successfully identified from processed dipmeter data the tilt axis are mainly trending n s in sandstones associated to westward transport of sediments the sliding surfaces s1 and s3 correspond to e w trending tilt axis tentatively correlated either to the flexural subsidence of the basin or to anticline growth during sedimentation south of the studied area combination of these sedimentary and tectonic directions results in a ne sw striking submarine slope which locally controls the gravity driven deformations especially on the s2 sliding surface finally nnw sse trending tilts above the uppermost s3 sliding surface are interpreted as the result of infilling on the side of the scar produced by sliding

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

tropospheric rossby wave breaking and the nao nam objective analysis of several hundred thousand anticyclonic and cyclonic breaking rossby waves is performed for the northern hemisphere nh winters of 1958 2006 a winter climatology of both anticyclonic and cyclonic rossby wave breaking rwb frequency and size zonal extent is presented for the 350 k isentropic surface over the nh and the spatial distribution of rwb is shown to agree with theoretical ideas of rwb in shear flow composites of the two types of rwb reveal their characteristic sea level pressure anomalies upper and lower tropospheric velocity fields and forcing of the upper tropospheric zonal flow it is shown how these signatures project onto the centers of action and force the velocity patterns associated with the north atlantic oscillation nao and northern hemisphere annular mode nam previous studies have presented evidence that anticyclonic cyclonic breaking leads to the positive negative polarity of the nao and this relationship is confirmed for rwb over the midlatitudes centered near 50 n however an opposite and statistically significant relationship in which cyclonic rwb forces the positive nao and anticyclonic rwb forces the negative nao is shown over regions 20 to the north and south centered at 70 and 30 n respectively on a winter mean basis the frequency of rwb over objectively defined regions covering 12 of the area of the nh accounts for 95 of the nao index and 92 of the nam index a 6 hourly analysis of all the winters indicates that rwb over the objectively defined regions affects the nao nam without a time lag details of the objective wave breaking analysis method are provided in the appendix

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

electrochemical sensing of volcanic gases we report here the development and application of a compact geochemical nose incorporating electrochemical sensors for gas measurements in volcanic plumes a novel element of the instrument design is the arrangement of the sensors in a parallel array that enables near simultaneous exposure and fast response data analysis methods were developed that utilise the multi sensor output currents to extract gas mixing ratio abundances and eliminate cross sensitivities use of filter methods is demonstrated to remove baseline drift or instrument noise we introduce a new approach for analysis of measurements from sensors that have a slower response time e g hcl and apply this model to estimate hcl so2 ratios we deployed the sensor system at aso volcano japan detecting emissions from its fumarole field hot crater lake and a mixed plume we measured so2 h2s co and hcl ranging in abundance from 102 104 ppbv neither no2 nor cl2 were detected for the fumarolic gases molar ratios were measured as follows h2s so2 is 0 15 h2 so2 0 25 co so2 0 02 hcl so2 0 1 the crater lake plume s h2s so2 is 0 03 the compositions are discussed in terms of degassing equilibria and plume chemistry our instrument design represents a cost effective low power and highly portable system that can be readily adapted for operational surveillance of volcanic gases

the changing face of mount etna s summit area documented with lidar technology 1986 2007 period amounts to 112 12 10 6 m 3 a t a mean annual rate of 5 3 10 6 m 3 the comparison of the various surveys furthermore emphasizes the levels of accuracy and resolution of the different techniques applied the lidar technology used in 2007 allows production of high precision maps in near real time facilitating work concerning environmental hazards such as numerical simulations of e g lava flows citation neri m f mazzarini s tarquini m bisson i isola b behncke and m t pareschi 2008 the changing face of mount etna s summit area documented with lidar technology geophys res lett 35 l09305 doi 10 1029 2008gl033740

first observations of the fumarolic gas output from a restless caldera implications for the current period of unrest 2005 2013 at campi flegrei 1 the fumarolic gas output has not been quantified for any of the currently deforming calderas worldwide due to the lack of suitable gas flux sensing techniques in view of resumption of ground uplift since 2005 and the associated variations in gas chemistry campi flegrei in southern italy is one of the restless calderas where gas flux observations are especially necessary here we report the first ever obtained estimate of the campi flegrei fumarolic gas output based on a set of multigas surveys performed in 2012 and 2013 with an ad hoc designed measurement setup we estimate that the current campi flegrei fumarolic sulphur s flux is low on the order of 1 5 2 2 tons day suggesting substantial scrubbing of magmatic s by the hydrothermal system however the fumarolic carbon dioxide co2 output is 460 160 tons day mean sd which is surprisingly high for a dormant volcano in the hydrothermal stage of activity and results in a combined fumaroles soil co2 output of 1560 tons day assuming magma to be the predominant source we propose that the current co2 output can be supplied by either i a large 0 6 4 6 km3 deeply stored 7 km magmatic source with low co2 contents 0 05 0 1 wt or ii by a small to medium sized 0 01 0 1 km3 but co2 rich 2 wt magma possibly stored at pressures of 100 to 120 mpa independent geophysical evidence e g inferred from geodetic and gravity data is needed to distinguish between these two possibilities

moist dynamics and orographic precipitation in northern and central california during the new year s flood of 1997 abstract the dynamics of moist orographic flows during the january 1997 floods in northern and central california are investigated using numerical simulations computed with the fifth generation pennsylvania state university national center for atmospheric research psu ncar mesoscale model mm5 early in the event 31 december 1996 1 january 1997 the low level winds offshore of california s central coast were blocked by the topography of the santa lucia range and the low level winds in the central valley were blocked by the topography of the central sierra nevada range in contrast moisture laden winds along the northern coast ranges and the northern sierra nevada flowed over topographic barriers as the core of humid air migrated to the south over 24 h the low level barrier jets weakened as the atmospheric stability decreased bringing heavy rainfall to the central and southern sierra nevada at the end of the event the heavy precipitation during this event was largely controlled by the interactio

the north atlantic oscillation response to large scale atmospheric anomalies in the northeastern pacific abstractingredients in the north pacific flow influencing rossby wave breakings in the north atlantic and the intraseasonal variations of the north atlantic oscillation nao are investigated using both reanalysis data and a three level quasigeostrophic model on the sphere first a long term run is shown to reproduce the observed relationship between the nature of the synoptic wave breaking and the phase of the nao furthermore a large scale low frequency ridge anomaly is identified in the northeastern pacific in the days prior to the maximum of the positive nao phase both in the reanalysis and in the model a large scale northeastern pacific trough anomaly is observed during the negative nao phase but does not systematically precede it then short term linear and nonlinear simulations are performed to understand how the large scale ridge anomaly can act as a precursor of the positive nao phase the numerical setup allows for analysis of the propagation of synoptic waves in the eastern pacific in the p

first determination of magma derived gas emissions from bromo volcano eastern java indonesia abstract the composition and fluxes of volcanic gases released by persistent open vent degassing at bromo volcano east java indonesia were characterised in september 2014 from both in situ multi gas analysis and remote spectroscopic dual uv camera measurements of volcanic plume emissions our results demonstrate that bromo volcanic gas is water rich h2o so2 ratios of 56 160 and has co2 so2 4 1 0 7 and co2 stot 3 2 0 7 ratios within the compositional range of other high temperature magma derived gases in indonesia h2 h2o and h2s so2 ratios constrain a magmatic gas source with minimal temperature of 700 c and oxygen fugacity of 10 17 10 18 bars uv camera sensing on september 20 and 21 2014 indicates a steady daily mean so2 output of 166 38 t d 1 which is ten times higher than reported from few previous studies our results indicate that bromo ranks amongst the strongest sources of quiescent volcanic so2 emission measured to date in indonesia being comparable to merapi volcano in central java by combining our results for the gas composition with the so2 plume flux we assess for the first time the fluxes of h2o 4725 2292 t d 1 co2 466 83 t d 1 h2s 25 12 t d 1 and h2 1 1 0 8 from bromo our study thus contributes a new piece of information to the still limited data base for volcanic gas emissions in indonesia and confirms that much remain to be done to fully assess the contribution of this very active arc region to global volcanic gas fluxes

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

latest oligocene late miocene lacustrine systems of the north central part of the ebro basin spain sedimentary facies model and palaeogeographic synthesis abstract in the central part of the ebro basin spain north of the ebro river three allostratigraphic or tectosedimentary units differentiated within the latest oligocene late miocene upper agenian vallesian interval are sedimentologically characterized these deposits represent carbonate and sulphate lacustrine environments fed by pyrenean alluvial systems luna system and huesca system in each unit several facies associations or lithofacies were mapped these interfinger through time gypsum lithofacies occupy the southernmost part of the study area and are surrounded by carbonate and or detrital lithofacies to the north each lithofacies consists of different carbonate sulphate and or detrital facies arranged in simple sequences decimetres to metres thick the four types of sequences characterized reflect a complex shallowing evolution involving carbonate or sulphate contexts thus each lithofacies represents the sedimentation in a particular lacustrine or alluvial subenvironment a single lacustrine system is proposed for the central part of the basin its evolution followed cycles of water level variations which caused kilometre scale migrations of the lake shoreline in this model two distinct situations or lakes alternated through time a one represents high levels associated with a single body of dilute carbonate water where massive carbonate facies formed influenced by organism proliferation these lakes had wide palustrine vegetated margins in which bioturbated facies developed b the other represents low levels that correspond to a playa lake model laminated sulphate deposits formed in the lake waters while nodular gypsum originated in the surrounding saline mud flats and within the exposed previously deposited carbonate sediments transitions from one situation to the other including minor water level fluctuations within carbonate sedimentation conditions were marked by the development of laminated and stromatolitic facies lake level variations were caused by climatic cycles and gave rise to the simple sequences and to the lithofacies lateral relationships recognized in this study correlation among tectosedimentary units in the studied pyrenean domain and in the iberian domain of the ebro basin shows that for units n1 and n2 the facies that resulted from dilute carbonate waters are rare in the lacustrine areas of the iberian margin this indicates that a strong hydrological contrast existed between both regions on this basis a theoretical asymmetrical facies model is proposed for the single lacustrine basin that extended over these regions

a review on the applications of image logs in structural analysis and sedimentary characterization abstract image logs provide important information on lithology sedimentary textures paleoflow directions fractures and in situ stress analysis lacking of criteria used for establishing the image log facies limits the applications of image logs in sedimentary reservoir interpretation this paper provides a thoroughgoing review focusing on the recent applications of borehole image logs for sedimentological and structural description and interpretation and aims to establish image log facies which can provide guidelines in sedimentary reservoir interpretation this paper firstly summarizes the principles and basic characteristics of various imaging logging tools and then briefly introduces the pre processing workflow of the image log data then the generated images are used for depth and orientation shifts of cores by calibrating individual sedimentary and structural features descriptive and concise image log facies are established based on combinations of image textures including dip type dip pattern and color scheme and the characteristics as well as physical criteria for each individual image facies are summarized the established image log facies are then interpreted in terms of structural and sedimentological features such as lithology sedimentary structures vugs fractures and faults the image log facies and its stacking patterns are then used to interpret the lithofacies associations by calibrating with cores and conventional logs natural fractures and induced fractures are recognized by image logs and the principles of breakouts and drilling induced fractures for in situ stress analysis are reviewed then the applications of image logs in investigation of fracture attitudes and states as well as in computation of fracture parameters are summarized the procedures to evaluate fracture effectiveness through image logs are discussed at last the application of image logs for structural dip analysis is reviewed and image logs are used for recognizing faults fracture sets and attitudes of stratum through the dip patterns the basic procedures for paleocurrent reconstruction which includes dip picking of cross beddings structural dip determination and structural dip removal are reviewed then the paleocurrent directions of the lower cretaceous bashijiqike formation in the kuqa depression were reconstructed which could help further understanding of the depositional systems this review will help extend the utility of image logs in interpreting small to large scale sedimentary and structural features and bridges the gaps between well log analysis and sedimentary and structural interpretation

integration of outcrop and borehole image logs for high resolution facies interpretation example from a fluvial fan in the ebro basin spain electrical borehole image logs yield high resolution information about variations in micro resistivity along the borehole wall to interpret these variations in terms of sedimentary structures and lithofacies types calibration with real rock is needed normally the only real rock available is core and this only provides one dimensional information in this paper the interpretation of fluvial facies types from borehole image logs was established by direct comparison with outcrops four fluvial facies associations were established in an outcrop study of a low net to gross fluvial succession i meandering rivers ii braided rivers iii crevasse deltas and iv crevasse splays the lithofacies characteristics and palaeocurrent distributions of each fluvial facies association were established two 200 m deep wells were drilled behind the cliff face outcrops one well was cored to a depth of 150 m and borehole image logs were recorded in both wells the wells were correlated with the outcrop the borehole image logs were analysed by their vertical colour succession and the dipmeter pattern image log facies were established and these were interpreted in terms of the fluvial facies associations encountered in the corresponding outcrops the study of borehole image logs yields a set of diagnostic criteria for a detailed fluvial facies interpretation and the establishment of depositional trends and thus provides a powerful tool for the direct interpretation of fluvial facies in a reservoir setting

impact of distinct origin locations on the life cycles of landfalling atmospheric rivers over the u s west coast author s zhou y kim h abstract 2019 american geophysical union all rights reserved an atmospheric river ar event represents strong poleward moisture transport and is defined as a series of spatiotemporally connected instantaneous ar objects utilizing an ar tracking algorithm with a depth first search a widely used algorithm in computer science we examine the life cycle characteristics of ar events that make landfall over the u s west coast by their distinct origin locations landfalling ar events from the northwest pacific 120 e 170 w wlar events temporally last longer 5 3 versus 3 6 days on average and have stronger intensity of integrated vapor transport 508 versus 388 kg m 1 s 1 on average than those originating from the northeast pacific 125 w 170 w elar events a persistent tripole geopotential height anomaly pattern over the north pacific modulates the origin locations and propagation of landfalling ar events wlar events are associated with anomalous highs over northeastern asia and the northeast pacific and an anomalous low over the central north pacific this pattern provides favorable conditions for wlar events to start propagate northeastward and make landfall in the northwestern west coast wlar events contribute approximately 25 of the total winter precipitation over washington and british columbia elar events are associated with a similar tripole pattern to the wlar events with an eastward shift the anomalous low over the northeast pacific helps elar events to start propagate northeastward and make landfall in the southwestern west coast precipitation induced by elar events contributes up to 30 of total winter precipitation over california

diffuse emission of hydrogen from poas volcano costa rica america central we report the results of four soil h2 surveys carried out in 2000 2003 at poas volcano costa rica to investigate the soil h2 distribution and evaluate the diffuse h2 emission as a potential surveillance tool for poas volcano soil gas h2 contents showed a wide range of concentration from 0 2 to 7 059 ppmv during the four surveys maps of soil gas h2 based on sequential gaussian simulation showed low h2 concentration values in the soil atmosphere 0 7 ppmv for most of the study area whereas high soil gas h2 values were observed inside the active crater of poas a significant increase in soil gas h2 concentration was observed inside the active crater during 2001 and 2002 with respect to year 2000 followed by a decrease in 2003 the observed spatial and temporal variations of soil h2 concentration have been well correlated with seismicity microgravimetry and fumarolic chemistry changes which occurred during this study these observations evidence changes in the shallow magmatic hydrothermal system of poas and it might be related to a potential magmatic intrusion during the period 1998 2004 therefore monitoring diffuse h2 emission of poas has become an important geochemical tool for the monitoring of its volcanic activity

characterization of braided river delta facies in the tarim basin lower cretaceous application of borehole image logs with comparative outcrops and cores abstract borehole electrical image log with core like presentation is an efficient way to conduct sedimentary description in the subsurface the key is to set up a series of geological diagnostic criteria the subsurface lower cretaceous bashijiqike formation in the kelasu belt kuqa depression described as a sedimentary facies of braided river delta front has measured a mass of borehole image logs and open hole logs at depths more than 6000 m combined with comparative outcrops limited cores and thin sections high quality borehole images were fine calibrated to reveal their sedimentary details with the aim of subtle sedimentary interpretation in the uncored intervals the image elements all have corresponding geological indications the lithologies are interpreted including mudstones siltstones fine and medium sandstones and conglomerates and the sedimentary structures are interpreted in terms of various bedding types scoured surface and stacking modes thus interdistributary bay sandy or conglomerate subaqueous distributary channel and channel mouth bar are interpreted based on the lithologies sedimentary structures and textures basal and top contacts and succession variations furthermore determination of paleo current direction using borehole image logs is proposed for some time but is far from mature and need to consider tectonic deformation settings of studied stratigraphy based on this the paleo current in the kelasu belt is interpreted to flow southward from the southern tianshan to the depression during the early cretaceous which is consistent with the results derived from the heavy mineral analysis however the subaqueous distributary channels could frequently migrate locally and the paleo current direction changed at localities with an offset angle varied between 30 and 150 regionally the scale of single sand body decreases lakeward and the sand body may stretch at a maximum distance of 685 1 m along the flow direction the diagnostic criteria and the workflow for borehole image interpretation in this study will have potential application to subsurface sedimentary description and guide sedimentary architecture where cores are not available

sulfur isotopic compositions of fumarolic and plume gases at mount etna italy and inferences on their magmatic source 1 here we report new data on the sulfur isotopic compositions 34s of fumarolic and plume gases collected at mount etna volcano during 2008 2009 while low temperature fumaroles are affected by postmagmatic processes that modify the pristine isotopic signature high temperature and plume gases allow establishment of a 34s range of 0 1 for magmatic so2 we compared our data with those from s dissolved in primitive melt inclusions from 2002 lava and in whole rocks that erupted during the past two thousand years such a comparison revealed that 34s is systematically lower for magmatic gases than for sulfur dissolved in the melt we modeled how isotopic fractionation due to magma degassing process may vary 34s value in both the melt and gaseous phases this modeling required assessment of the fractionation factor gas melt the most recent measurements on the oxidation state of sulfur in basaltic melt inclusions indicate that nearly all s is dissolved as sulfate s6 which would be possible in oxidized magmatic systems nno 1 under these conditions the exsolved gaseous phase is depleted with respect to the melt and the proposed model fits both gas and melt data and constrains the etnean magmatic 34s to 1 0 1 5 it is remarkable that the assessed redox conditions which are significantly more oxidizing than previously thought are able to explain why the dominant sulfur species measured in the etnean plume is so2

on the origin of crevasse splay amalgamation in the huesca fluvial fan ebro basin spain implications for connectivity in low net to gross fluvial deposits abstract floodplain deposits are abundant in low gradient dryland river systems but their contribution to connected reservoir volumes has not yet been fully acknowledged due to their poor detectability with typical wireline log suites and relatively lower reservoir quality this study presents an analysis of stacked crevasse splays in the distal part of the miocene huesca fluvial fan ebro basin spain vertical stacking of crevasse splays implies local aggradation of the active channel belt lateral amalgamation of crevasse splays created an elevated rim around their feeder channel raising its bankfull height subsequent crevasse splays were deposited on top of their predecessors creating sand on sand contact through incision and further raising the active channel belt this process of channel belt super elevation repeated until an upstream avulsion occurred amalgamated crevasse splays constitute connected reservoir volumes up to 107 m3 despite their lower reservoir quality they effectively connect channel deposits in low net to gross fluvial stratigraphy and hence their contribution to producible volumes should be considered unswept intervals of amalgamated crevasse splays may constitute a secondary source of natural gas their interval thickness can serve as a proxy for feeder channel dimensions which can in turn be used to estimate the degree of stratigraphic connectivity

stable hydrogen and oxygen isotopic compositions of water vapor in volcanic plumes sampled in glass bottles using cavity ring down spectroscopy abstract the isotopic compositions 2h and 18o of fumarolic h2o emitted during volcanic eruptions can distinguish the type of eruption magmatic or phreatic but direct sampling of fumarolic h2o in eruptive volcanoes is often neither practical nor safe in this study we developed a new analytical system to safely determine the isotopic compositions of fumarolic h2o from the volcanic plume samples taken in glass bottles the system consisted of stainless steel gas introduction line and a cavity ring down spectroscopic unit in the 1 l glass sample bottles analytical precision 1 was estimated to be better than 2 and 0 3 respectively when 3400 ppmv of h2o was introduced and better than 3 2h and 0 4 18o when 1800 ppmv of h2o was introduced the h2o concentration accuracy was better than 5 using this in situ collection method and the analytical system we determined the isotopic compositions of h2o in volcanic plume samples taken at iwo yama in the kirishima volcano group japan and deduced the isotopic composition of fumarolic h2o from the volcanic plume the reciprocal of the h2o concentration in the plume samples showed a good linear relationship with the isotopic composition the isotopic composition of fumarolic h2o from iwo yama estimated from the plume samples directly corresponded to the determined fumarolic h2o this method improves upon previous analyses to obtain the isotopic compositions of fumarolic h2o particularly by reducing tedious time consuming and dangerous sampling of water vapor at volcanic fumaroles

how rossby wave breaking over the pacific forces the north atlantic oscillation 1 anticyclonic rossby wave breaking rwb over a well defined limited area region of the east pacific leads to the positive polarity of the north atlantic oscillation nao by locally piling up wave activity where it may be advected downstream resulting in increased wave activity flux and anticyclonic rwb over the subtropical atlantic a composite time series shows that pacific rwb occurs several days prior to the atlantic rwb and the peak of the nao index following pacific rwb a channel of increased pseudomomentum flux extends from the pacific wave breaking region northeastward toward midlatitudes of eastern north america where pseudomomentum density accumulates for several days prior to moving eastward and leading to anticyclonic rwb over the atlantic

artificial neural network assisted prediction of dissolution spatial distribution in the volcanic weathered crust a case study from chepaizi bulge of junggar basin northwestern china abstract the reservoir rocks in the volcanic weathered crust are characterized by plentiful dissolution pores caverns and fractures however as an essential control factor of the reservoir distribution volcanic dissolution is often ignored in quantitative studies in this paper we propose a complete artificial intelligence workflow to model and predict the volcanic dissolution distribution by integrating the image logging semi quantitative analysis with seismic prediction a synthetic reservoir property named dcv dissolution comprehensive values is generated as logging curves from xrmi resistivity pseudo pictures to indicate the intensity of dissolution these curves are then used as the target for the seismic based prediction in an artificial intelligence framework a multi layer artificial neural network ann model is constructed in order to map the seismic attributes into the dcv the methodology is demonstrated on a real case study from the junggar basin in northwestern china the maps and profiles from the prediction represent the dissolution values in the volcanic weathered crust the predictions are consistent with the geological volcanic dissolution model provided by geological knowledge it is concluded that the spatial dissolution distribution in volcanic weathered crust can be reliably predicted by this integrated method

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

understanding a submarine eruption through time series hydrothermal plume sampling of dissolved and particulate constituents west mata 2008 2012 four cruises between 2008 and 2012 monitored the continuing eruption of west mata volcano in the ne lau basin as it produced plumes of chemically altered water above its summit although large enrichments in 3he co2 fe and mn were observed in the plumes the most notable enrichment was that of h2 which reached concentrations as high as 14 843 nm strongly enriched h2 concentrations in the water column result from reactions between seawater or magmatic water and extremely hot rocks in 2008 the observation of elevated h2 concentrations in the water column above west mata pointed to vigorous ongoing eruptions at the volcano s summit the eruption was confirmed by visual observations made by the rov jason 2 in 2009 and demonstrated that h2 measurements are a vital instrument to detect ongoing volcanic eruptions at the seafloor elevated h2 in 2010 showed that the eruption was ongoing although at a reduced level given a maximum h2 concentration of 4410 nm in 2012 h2 levels in the water column declined significantly to a maximum of only 7 nm consistent with visual observations from the quest 4000 rov that found no evidence of an ongoing volcanic eruption methane behaved independently of other measured gases and its concentrations in the hydrothermal plume were very low we attribute its minimal enrichments to a mixture of mantle carbon reduced to ch4 and biological ch4 from diffuse flow sites this study demonstrates that ongoing submarine volcanic eruptions are characterized by high dissolved h2 concentrations present in the overlying water column

processes facies and architecture of fluvial distributary system deposits abstract there is evidence from the stratigraphic record of examples of fluvial deposits that were the products of deposition from river systems which had decreasing discharge down flow and transitions from proximal channelised to distal unconfined flow these deposits form fan shaped bodies several tens of kilometres in radius and their stratigraphic architecture is aggradational with no evidence of deep incision driven by base level fall the fluvial systems that generated these deposits formed under conditions for which there is no complete analogue today an endorheic basin with a relatively arid climate adjacent to an uplifted area with higher precipitation a conceptual model for fluvial systems of this type has therefore been built on the basis of outcrop examples and a consideration of the controls on sedimentation proximal areas are characterised by amalgamated coarse pebbly and sandy channel deposits with little preservation of overbank facies channel dimensions are generally smaller in the medial areas but sizes are variable deposits are of braided meandering and simple channels which show varying degrees of lateral migration the channel fills may be mud or sand with overbank flow processes playing an important role in filling channels abandoned on the floodplain after avulsion the proportion of overbank deposits increases distally with sheets of sand deposited as lateral and terminal splays by unconfined flow interconnection of sandstone bodies is poor in the distal areas because channel fill bodies are sparse small and are not deeply incised the radial pattern of the sediment body forms by the repeated avulsion of channels active channels build up lobes on the alluvial plain and rivers switch position to follow courses on lower lying areas the term fluvial distributary system is here used to describe a river system which has a downstream decrease in discharge and has a distal zone which is characterised either by terminal splays on to a dry alluvial plain or a lake delta during periods of lake highstand

climatology of intrusions into the tropical upper troposphere regions of upper tropospheric equatorial westerly winds observed over the pacific and atlantic oceans during northern fall to spring are important for extratropical tropical interactions this paper focuses on one feature of these westerly ducts that has received relatively little attention to date the occurrence of rossby wave breaking events that transport tongues of extratropical air deep into the tropics mix tropical and subtropical air and can affect deep convection a climatology of these intrusion events formed from 20 years of meteorological analyses shows a strong dependence on the basic state flow notably intrusion events are found to occur almost exclusively within westerly ducts with more events in the presence of stronger equatorial westerlies it is also found that there is strong interannual variability in the frequency of pacific events with fewer events during the warm phases of enso consistent with the changes in the basic flow since these intrusion events laterally mix trace constituents and have been linked to tropical convection their spatial and temporal variability may cause related variability in the distribution of trace constituents and tropical convection

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

impact of rossby wave breaking on u s west coast winter precipitation during enso events abstractthis study demonstrates that water vapor transport and precipitation are largely modulated by the intensity of the subtropical jet transient eddies and the location of wave breaking events during the different phases of enso clear differences are found in the potential vorticity pv meteorological fields and trajectory pathways between the two different phases rossby wave breaking events have cyclonic and anticyclonic regimes with associated differences in the frequency of occurrence and the dynamic response during la nina there is a relatively weak subtropical jet allowing pv to intrude into lower latitudes over the western united states this induces a large amount of moisture transport inland ahead of the pv intrusions as well as northward transport to the west of a surface anticyclone during el nino the subtropical jet is relatively strong and is associated with an enhanced cyclonic wave breaking this is accompanied by a time mean surface cyclone which brings zonal moisture tran

a methodology for determining orientations in unscribed core abstract this paper describes a simple methodology for determining paleocurrent directions or fracture orientations from core that has traditionally been considered unoriented provided the core does not intersect bedding at a 90 angle and that the attitude of bedding strike and dip and the drill hole azimuth and inclination are known paleocurrent directions and fracture orientations can be determined in present day geographic coordinates without the need for scribed core this technique supplements dip meter and borehole image logs and allows the use of structures that are too small to be imaged geophysically

determination of paleocurrent direction from oblique sections of trough cross stratification a precise approach the study of paleoflow patterns is an essential part of basin analysis cross stratification both planar and trough is the principal directional structure used for paleocurrent analysis trough cross stratification is especially characteristic of fluvial deposits where it is typically formed by the primary current and correlates strongly with the flow direction harms and fahnestock 1965 wermund 1965 williams 1968 barrett 1970 mcgowen and garner 1970 dott 1973 michelson and dott 1973 high and picard 1974 the only exception reported by meckel 1967 is an artifact of an erroneous sampling technique high and picard 1974 however the paucity of three dimensional exposures of trough cross strata that are suitable for direct measurement of trough axis orientations quite often hinders the systematic collection of paleocurrent data with a view to overcoming this problem attempts have been made to estimate paleoflow directions from two dimensional exposures of trough cross strata slingerland and williams 1979 decelles et al 1983 because they are much more common slingerland and williams 1979 proposed two specific ways of determining the orientations of trough axes from two dimensional exposures according to their first method a single strike measured on a trough side can be corrected to give the trough axial azimuth with reference to the plunge of the trough measured from a quasi three dimensional exposure slingerland and williams 1979 p 731 the plunge direction itself after necessary tilt correction however indicates the flow direction and if it can be measured beyond doubt no further measurement of any other part of the trough is required this kind of exposure is also not qualitatively very different from a three dimensional one the second method proposed by slingerland and williams 1979 involves estimation of the trough axial azimuth by measuring on perfectly two dimensional vertical exposures the face azimuths and two

overbank and channelfill deposits of the modern yellow river delta abstract the huanghe is noted for its high transport rate of silt and clay which may reach depth averaged values of 200 kg m 3 during peak discharge the sediment load transported through the river on entering the delta plain amounts to 1012 kg per year in contrast to most other large deltas only one distributary channel is active at any one time the high sediment load causes the rivermouth to prograde at a yearly rate of 1 4 km into the shallow less than 20 m deep bohai gulf the vertical aggradation of the channel belt and mouth bar complex is also rapid decimetres per year on average so that after a normal average of twelve years increasing channel instability and avulsion create the start of a new delta lobe a series of satellite images covering the last fifteen years has provided insight in the evolution of the river pattern as well as the progradation of the delta front a newly developed distributary passes from a multichannel to a single straight channel system and ends with the formation of meanders the protruding mature delta lobe shows a radiating pattern of crevasse channels overbank crevasse deposits are made of vertically stacked dm scale waning flow sequences structurally characterized by from bottom to top small scour and fills even parallel lamination and climbing ripple crosslamination accumulation rates on crevasse splays can be predicted on the basis of estimated river sediment discharge it can be concluded that each sequence has been deposited within a few hours and that tidal waterlevel fluctuations may have played a role in the generation of a single sequence

connectivity of fluvial point bar deposits an example from the miocene huesca fluvial fan ebro basin spain the huesca fluvial fan miocene ebro basin spain contains a low gradient mixed load fluvial system a detailed outcrop study of its meandering river deposits shows that the preservation of elongate channel floor sandstone ribbons is common and that these deposits create a continuous along stream sand to sand connectivity between successive crescent shaped sandy point bar accumulations on both sides of the channel the combined appearance of the sandstone resembles a string of beads consisting of a thin sinuous ribbon with thick and wide protuberances on either side the studied meandering river sandstone bodies are laterally amalgamated and vertically stacked with a net to gross n g ratio of about 40 they occur in 1 1 5 km 0 62 1 mi wide northeast southwest oriented elongate meander belts occupying paleochannels beyond these belts the sandstone is limited to isolated bodies with a very low n g ratio a generic model of the string of beads geometry based on the outcrop data analysis showed a significant increase of bulk rock volume for the connected string of beads compared with the model of isolated point bars the outcrop results demonstrate the potential for channel floor sandstone bodies to be preserved in a low gradient mixed load fluvial system and their importance in connecting point bar units in an along stream direction we recommend that fluvial reservoir architecture modeling programs include a function that allows the connectivity between channel floor and point bar architectural elements this may greatly impact the estimated reservoir volumes and recovery factors in primary and secondary production as well as influence the sweep efficiency of enhanced recovery technologies marinus e donselaar received his m sc degree in geology from the university of utrecht and his doctor of science degree in reservoir geology from delft university of technology both in the netherlands he worked at the comparative sedimentology division at the university of utrecht since 1987 he has been a lecturer in sedimentology at delft university of technology his research interests are in the modeling of fluvial and barrier island reservoir architecture irina overeem has a ph d from the faculty of civil engineering and geosciences delft university of technology netherlands where she was an assistant professor in geological modeling from 2005 to 2007 her research focuses on the numerical modeling of fluviodeltaic processes over the last six years she has held a position at institute of arctic and alpine research instaar and she is presently working at the community surface dynamics modeling facility at the university of colorado

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

mass loss on himalayan glacier endangers water resources 1 ice cores drilled from glaciers around the world generally contain horizons with elevated levels of beta radioactivity including 36 cl and 3 h associated with atmospheric thermonuclear bomb testing in the 1950s and 1960s ice cores collected in 2006 from naimona nyi glacier in the himalaya tibet lack these distinctive marker horizons suggesting no net accumulation of mass ice since at least 1950 naimona nyi is the highest glacier 6050 masl documented to be losing mass annually suggesting the possibility of similar mass loss on other high elevation glaciers in low and mid latitudes under a warmer earth scenario if climatic conditions dominating the mass balance of naimona nyi extend to other glaciers in the region the implications for water resources could be serious as these glaciers feed the headwaters of the indus ganges and brahmaputra rivers that sustain one of the world s most populous regions

characteristics of natural fractures in the upper paleozoic coal bearing strata in the southern qinshui basin china implications for coalbed methane cbm development abstract natural fractures as the effective storage space and fluid flow pathway of hydrocarbons play a critical role in the exploration and development of unconventional gas resources in the coal bearing strata in the present study to reveal the effects of natural fractures on coalbed methane cbm preservation and development the types origins and development characteristics of natural fractures in the upper paleozoic permian shanxi formation in the southern qinshui basin were systematically described and analyzed based on outcrops cores borehole image logs thin sections and sem four types of natural fractures have been identified in the shanxi formation according to their geologic origins including the endogenic fractures cleats and exogenous fractures in the no 3 coal seam and tectonic fractures and diagenetic fractures in its roof and floor tectonic fractures can be further divided into small faults intraformational shear fractures intraformational open fractures and slip fractures while diagenetic fractures are mainly bed parallel fractures the statistical results show that the development and distribution characteristics of those types of fractures are significantly different which are mainly influenced by lithology layer thickness and geological structure further natural fractures with different types and distributions show different influences on cbm preservation and well productivity exogenous fractures can effectively improve the seepage capability of coal reservoirs and are conducive to cbm wells productivity whereas endogenic fractures have less contributions to coal permeability due to their poor effectiveness the intraformational open fractures in the fold axis zones and intraformational shear fractures and small faults in the fault zones are generally excessive developed those fractures may result in gas dissipation and external water supplement which have negative effects on cbm preservation and production however moderate developed intraformational shear fractures in the sandstone roof can favorably affect the pressure reduction of coal reservoir and improve the recovery potential of unconventional gas resources these investigations may serve as a geological basis for unconventional gas exploration and development of the upper paleozoic coal bearing strata in the southern qinshui basin

the crater lake of ilamatepec santa ana volcano el salvador insights into lake gas composition and implications for monitoring we here present the first chemical characterization of the volcanic gas plume issuing from the santa ana crater lake a hyper acidic crater lake ph of 0 2 to 2 5 in north western el salvador our results obtained during regular surveys in 2017 and 2018 using a multi gas instrument demonstrate a hydrous gas composition h2o so2 ratios from 32 to 205 and so2 as the main sulfur species h2s so2 0 03 0 1 we also find that gas composition evolved during our investigated period with the co2 so2 ratio decreasing by one order of magnitude from march 2017 37 2 9 7 to november 2018 3 this compositional evolution toward more magmatic so2 rich compositions is interpreted in the context of the long term evolution of the volcano following its 2005 and 2007 eruptions we find that in spite of reduced background level seismicity the magmatic gas supply into the lake was one order of magnitude higher in march 2017 total volatile flux 20 200 30 200 t day than in the following periods total volatile flux 900 10 167 t day we propose that the elevated magmatic hydrothermal transport in march 2017 combined with a 15 reduction in precipitation caused the volume of the lake to decrease ultimately reducing its sulfur absorbing and scrubbing capacity and hence causing the gas plume co2 so2 ratio to decrease the recently observed increases in temperature acidity and salinity of the lake are consistent with this hypothesis we conclude that the installation of a continuous fully automated multi gas is highly desirable to monitor any future change in lake plume chemistry and hence the level of degassing activity

validation of a novel multi gas sensor for volcanic hcl alongside h2s and so2 at mt etna volcanic gas emission measurements inform predictions of hazard and atmospheric impacts for these measurements multi gas sensors provide low cost in situ monitoring of gas composition but to date have lacked the ability to detect halogens here two multi gas instruments characterized passive outgassing emissions from mt etna s italy three summit craters voragine vor north east crater nec and bocca nuova bn on 2 october 2013 signal processing sensor response model srm approaches are used to analyse h2s so2 and hcl so2 ratios a new ability to monitor volcanic hcl using miniature electrochemical sensors is here demonstrated a direct exposure multi gas instrument contained so2 h2s and hcl sensors whose sensitivities cross sensitivities and response times were characterized by laboratory calibration srm analysis of the field data yields h2s so2 and hcl so2 molar ratios finding h2s so2 0 02 0 01 0 03 with distinct hcl so2 for the vor nec and bn crater emissions of 0 41 0 38 0 43 0 58 0 54 0 60 and 0 20 0 17 0 33 a second multi gas instrument provided co2 so2 and h2o so2 and enabled cross comparison of so2 the multi gas measured so2 hcl h2s co2 h2o compositions provide insights into volcanic outgassing h2s so2 ratios indicate gas equilibration at slightly below magmatic temperatures assuming that the magmatic redox state is preserved low so2 hcl alongside low co2 so2 indicates a partially outgassed magma source we highlight the potential for low cost hcl sensing of h2s poor hcl rich volcanic emissions elsewhere further tests are needed for h2s rich plumes and for long term monitoring our study brings two new advances to volcano hazard monitoring real time in situ measurement of hcl and improved multi gas srm measurements of gas ratios

the late palaeozoic early mesozoic from the catalan pyrenees spain 60 myr of environmental evolution in the frame of the western peri tethyan palaeogeography the eastern catalan pyrenees form the southernmost segment of the pyrenean axial zone they experienced complex multistage process as the result of both the variscan and the pyrenean orogenic cycles after the late palaeozoic several small extensional sub basins were filled by continental successions as a response to the changing tectonic setting within the frame of the southwestern europe this stratigraphic record perfectly exposed in the studied eastern pyrenean areas preserves the signatures of the late palaeozoic pangea break up during the progressive dismantling of the variscan chain up to the triassic diffused extension despite structural network being severely affected by cenozoic reworking the stratigraphic framework can be unravelled by the detailed sedimentological and stratigraphical analysis of the well exposed sequences in short this paper addresses facies patterns and architectural elements of late carboniferous permian triassic continental sections studied in the catalan pyrenees and aims to use these signatures for correlation not only at a regional scale but also within the broader picture of the southwestern europe our stratigraphical reconstruction clearly demonstrates that the thick studied succession consists of fluvial lacustrine basal units affected by intense volcanic activity and overlaying predominantly fluvial fining upwards units for each unit several lithofacies architectural elements and bounding surfaces of different order have been identified and their lateral and vertical staking characterized deposition and erosion processes are controlled by alternating periods of tectonic activity producing different stages of high and low subsidence the uplift of the sub basin margins and subsequent extended erosive events marked by angular unconformities on the strength of the major rank bounding surfaces analysis the studied sedimentary packages have been grouped into different tectono stratigraphic units and then correlated they have been contextualized within the latest palaeogeographic reconstructions of the studied sector contributing to detail the role of the study area within the frame of the s european palaeogeography

steam and gas emission rate from la soufriere volcano guadeloupe lesser antilles implications for the magmatic supply during degassing unrest abstract since its last magmatic eruption in 1530 ad la soufriere andesitic volcano in guadeloupe has displayed intense hydrothermal activity and six phreatic eruptive crises here we report on the first direct quantification of gas plume emissions from its summit vents which gradually intensified during the past 20 years gas fluxes were determined in march 2006 and march 2012 by measuring the horizontal and vertical distributions of volcanic gas concentrations in the air diluted plume and scaling to the speed of plume transport fluxes in 2006 combine real time measurements of volcanic h2s concentrations and plume parameters with the composition of the hot 108 5 c fumarolic fluid at exit fluxes in 2012 result from multigas analysis of h2s h2o co2 so2 and h2 concentrations combined with thermal imaging of the plume geometry and dynamics measurements were not only focused on the most active south crater sc vent but also targeted tarissan crater and other reactivating vents we first demonstrate that all vents are fed by a common h2o rich 97 98 mol fluid end member emitted almost unmodified at sc but affected by secondary shallow alterations at other vents daily fluxes in 2012 averaged 200 tons of h2o 15 tons of co2 4 tons of h2s and 1 ton of hcl increased by a factor 3 compared to 2006 even though modest such fluxes make la soufriere the second most important volcanic gas emitter in the lesser antilles arc after soufriere hills of montserrat taking account of other hydrothermal manifestations hot springs and diffuse soil degassing the summit fumarolic activity is shown to contribute most of the bulk volatile and heat budget of the volcano the hydrothermal heat output 8 mw exceeds by orders of magnitude the contemporaneous seismic energy release isotopic evidences support that la soufriere hydrothermal emissions are sustained by a variable but continuous heat and gas supply from a magma reservoir confined at 6 7 km depth by using petro geochemical data for la soufriere magma s and their dissolved volatile content and assuming a magmatic derivation of sulfur we estimate that the volcanic gas fluxes measured in 2012 could result from the underground release of magmatic gas exsolved from 1400 m3 d 1 of basaltic melt feeding the system at depth we recommend that fumarolic gas flux at la soufriere becomes regularly measured in the future in order to carefully monitor the temporal evolution of that magmatic supply

splay formation along the lower reaches of ephemeral rivers on the northern plains of arid central australia abstract splays are common features of many rivers and deltas forming as a result of overbank flooding and sediment deposition but they have rarely been described from modern dryland settings this paper investigates splay formation along the lower reaches of ephemeral rivers on the northern plains of arid central australia here splays vary from small lobate or tongue shaped features 1 km long to larger elongate features up to 4 km long and are supplied with rare floodwater and sediment through well defined breaches in the upper parts of the main channel banks in proximal and medial parts splay channels are incised up to 2 m into pre splay fine grained floodplain sediments but remain elevated between 0 5 m and 2 m above the main channels only in the very distal parts are splay channels less deeply incised either grading into the floodplain surface or terminating as sediment lobes that are deposited upon the floodplain aerial photographs and field observations indicate that many splays develop rapidly during large floods and are modified during infrequent subsequent floods four main stages of splay development are proposed 1 aggressive overbank flow results in bank line breaching and channel scour on the floodplain but little sediment deposition 2 coarse bed sediment is diverted from the main channel preventing further deepening at the bank line breach and slowing channel scour 3 increasing coarse sediment transport through the bank line breach and scoured channels leads to the formation of distal sediment lobes 4 subsequent floods divert around these distal lobes sometimes leading to further channel scour and lobe formation on the northern plains splays contribute to downstream decreases in the discharge and size of the main channels and splay deposits form local accumulations of gravelly sand in the predominantly fine grained floodplain successions some splays ultimately may evolve into distributaries or anabranches the dominantly erosional bases of these splay channels contrast with typical descriptions of many humid region splays but they do not display any geomorphological or sedimentological features that are necessarily diagnostic of formation in a dryland setting

variation of volcanic gas composition at a poorly accessible volcano sakurajima japan abstract volcanic gas compositions are estimated based on volcanic plume measurement with multi gas at a frequently erupting sakurajima volcano by application of airborne methods and automatic monitoring station on the flank during 2013 2019 the airborne measurements of co2 and h2o concentrations often suffer from large fluctuation of background likely due to entrainment of the atmosphere derived from different altitude by removing the background effect a representative volcanic co2 so2 mole ratio is estimated as 0 4 0 1 and we did not observe clear temporal variation the volcanic h2o so2 ratios are estimated as 30 70 with a large uncertainty because of the strong atmospheric perturbation the so2 h2s ratios show quite a large variation ranging from 1 to 800 the large so2 h2s ratios larger than 30 are observed during ash eruption and are suggested as a result of oxidation by atmosphere on hot ashes the small ratios less than 10 are observed when frequency of explosions is low variation of the so2 h2s ratios of the small values can be caused by variation of degassing pressure however the small variation of the co2 so2 ratio suggests a limited range of the pressure variation

total volatile flux from mount etna 1 the total volatile tv flux from mount etna volcano has been characterised for the first time by summing the simultaneously evaluated fluxes of the three main volcanogenic volatiles h2o co2 and so2 so2 flux was determined by routine doas traverse measurements while h2o and co2 were evaluated by scaling multigas sensed h2o so2 and co2 so2 plume ratios to the uv sensed so2 flux the time averaged tv flux from etna is evaluated at 21 000 t day 1 with a large fraction accounted for by h2o 13 000 t day 1 h2o dominates 70 the volatile budget during syn eruptive degassing while co2 and h2o contribute equally to the tv flux during passive degassing the co2 flux was observed to be particularly high prior to the 2006 eruption suggesting that this parameter is a good candidate for eruption prediction at basaltic volcanoes

soil gas co 2 ch 4 and h 2 distribution in and around las canadas caldera tenerife canary islands spain abstract diffuse degassing of co 2 ch 4 and h 2 was investigated at the surface environment of canadas caldera canary islands during the gas survey carried out in the summer of 1995 soil co 2 concentration varied significantly from atmospheric levels to 30 while soil ch 4 and h 2 contents ranged from 5 to 851 ppm and from 0 5 to 620 ppm respectively soil co 2 ch 4 and h 2 distribution suggests that high diffuse degassing at canadas caldera is volcanic structurally controlled anomalous soil h 2 concentrations were identified at the summit of teide and outside caldera boundaries where the most recent eruption of tenerife island occurred 13 c co 2 data showed a magmatic mixed magmatic biogenic and biogenic origin while a biogenic origin is suggested for soil ch 4 at canadas caldera and its surroundings by coupling the co 2 3 he ratio with the 3 he 4 he ratio of fumarolic gas samples from the summit of teide we propose three possible sources for carbon morb type organic carbon and carbonate

crevasse splay morphodynamics in a dryland river terminus rio colorado in salar de uyuni bolivia high resolution satellite imagery in combination with field investigation enables the analysis of splay morphological developments in time and space at the low gradient terminus of the modern rio colorado dryland river system in the salar de uyuni bolivia two sets 2004 2005 2010 2011 of satellite images are used to visualize splay morphological developments and three types of crevasse splays are identified based on temporal changes 1 new crevasse splays ncs refers to those splays that are not observed in the first set of images but can be observed on the second sets of images 2 changing crevasse splays ccs representing those splays that are found on the first set of images but their geometry has changed between two satellite observation periods and 3 inactive crevasse splays ics referred to those splays that are found on the first set of images but on the second set of images they remain the same or are partially overlapped by adjacent expanding crevasse splays the density or frequency of these three types of crevasse splays has no correlation with the distance to the starting point of the river or the local slope the cross sectional area of the studied river steadily decreases downstream and frequency analysis shows a downstream increase in the number of crevasse splays and suggests an exponential relationship with the river cross sectional area development of crevasse splays is often attributed to topographic lows between adjacent crevasse splays and they fill in the depression by compensational stacking e g li et al 2014 these amalgamated splays are capable of forming a large area of sheet sands and potentially provide an analogue for thin bedded hydrocarbon reservoirs

the degassing character of a young volcanic center cerro negro nicaragua cerro negro volcano is a young basaltic cinder cone which is part of the nicaraguan volcanic arc eruptive activity at cerro negro is characterized by explosive strombolian to subplinian eruptions driven by volatile rich basaltic magma ascending rapidly from various crustal depths 15 to 6 km resulting in the onset of precursory activity only 30 min before an eruption in this paper we present a comprehensive degassing characterization of the volcano over a 4 year period aimed at improving our understanding of the magmatic plumbing network and its relationship with regional tectonics a total of 124 individual soil gas samples were collected between 2010 and 2013 and analyzed for stable carbon isotopes 13c from co2 high temperature fumaroles were sampled for 18o d and 3he 4he isotope analysis and major degassing zones were mapped using soil co2 flux measurements gases at cerro negro are characterized by a strong 3he 4he mantle signature 6 3 to 7 3 ra magmatic 13c ratios 2 3 to 3 0 meteoric 18o and d ratios and stable co2 fluxes 31 t d 1 the lack of 13c fractionation and an increase in the relative mantle component from 2002 to 2012 suggest that the volatile flux at cerro negro originates from the mantle and ascends to the surface via a series of crustal fractures that act as permeable conduits despite the lack of new eruptions the hydrothermal system of cerro negro continues to evolve due to seasonal inputs of meteoric water slope failures that expose and bury sites of active degassing and bursts of regional seismicity that have the potential to open up new conduits for gas release as well as magma continuing geophysical and geochemical monitoring of the main edifice and the recently formed south zone is essential as the volcano remains overdue to erupt

how does the hot core of a volcanic plume control the sulfur speciation in volcanic emission 1 volcanic eruptions inject sulfur into the atmosphere mainly in form of so2 and h2s the ratio of these species h2s so2 which is usually used as the mirror of the oxidation state of the source magma varies significantly according to the type of activity tectonic setting etc this study aims to investigate the role of the hot core of plinian and sub plinian volcanic plumes t 600 c in sulfur speciation based on the thermodynamic equilibrium in this temperature range we consider the hot core as a box model in which 1000 c magmatic gas and 25 c ambient air are mixed and show that it functions as a hot oxidizing reactor for s species processes inside the hot core usually decrease the h2s content of the system but can either increase or decrease so2 depending on initial oxidation state thus the so2 injected into the atmosphere is not essentially generated directly from the magma but it can be produced in the hot core as the result of h2s oxidation besides volcanic cloud compositions do not mirror the source conditions considering three types of tectonic settings convergent plate divergent plate and hot spot we propose that h2s emission is more likely under reduced conditions in divergent plate and hot spot volcanic settings

variation of h2o co2 and co2 so2 ratios of volcanic gases discharged by continuous degassing of mount etna volcano italy 1 we applied the multi gas technique to measure compositions of the volcanic plumes continuously discharged from summit craters of voragine northeast and bocca nuova at mount etna in an attempt to estimate compositions of the source volcanic gases the estimated co2 so2 and h2o co2 ratios of the volcanic gases show a large variation ranging from 0 6 to 30 and from 1 to 18 respectively this variability overlaps with the compositional range of dissolved volatiles in melt inclusions and their coexisting bubbles in a magma chamber and can be caused by the low pressure degassing of a magma with variable bubble content ranging from 0 3 to 15 wt the variable bubble content in the magma is likely a result of supply of deep derived co2 rich gas phase to the chamber and subsequent bubble magma differentiation by bubble ascent in the magma chamber in contrast the variation of volcanic gas composition can also be caused by changes of degassing pressure gas magma separation pressure ranging from 0 to 100 mpa as a result of changes in the depth of the top of the convecting magma in volcanic conduits both mechanisms can cause similar compositional variations however the two mechanisms will result in contrasting correlations between the so2 emission rates and the gas compositions that can be examined by parallel observations of the emission rates and compositions in the future

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

interpretation of volcanic gas data from tholeiitic and alkaline mafic lavas the analyses of approximately 100 high temperature gas samples from erupting lavas of surtsey erta ale ardoukoba kilauea mount etna and nyiragongo exhibit erratic compositions resulting from analytical errors condensation effects reactions with sampling devices and contamination by atmospheric gases meteoric water and organic material computational techniques have been devised to restore reported analyses to compositions representative of the erupted gases the restored analyses show little evidence of short term variations the principal species are h2o co2 so2 h2 co h2s s2 and hcl the o2 fugacities range from nickel nickel oxide to a half order of magnitude below quartz magnetite fayalite there is no evidence for a unique magmatic gas composition instead the erupted gases show regular compositional trends characterized by decreasing co2 with progressive outgassing the gases from more alkaline lavas etna nyiragongo are distinctly richer in co2 while those from less alkaline surtsey or tholeiitic lavas erta ale ardoukoba tend to be richer in h2o kilauean gases range from co2 rich to h2o rich the total sulfur contents of the erupted gases show an excellent positive correlation with lava o2 fugacity all restored analyses are significantly lower in h2o and enriched in sulfur and co2 compared to the excess volatiles

hydrogen emissions from erebus volcano antarctica the continuous measurement of molecular hydrogen h2 emissions from passively degassing volcanoes has recently been made possible using a new generation of low cost electrochemical sensors we have used such sensors to measure h2 along with so2 h2o and co2 in the gas and aerosol plume emitted from the phonolite lava lake at erebus volcano antarctica the measurements were made at the crater rim between december 2010 and january 2011 combined with measurements of the long term so2 emission rate for erebus they indicate a characteristic h2 flux of 0 03 kg s 1 2 8 mg day 1 the observed h2 content in the plume is consistent with previous estimates of redox conditions in the lava lake inferred from mineral compositions and the observed co2 co ratio in the gas plume 0 9 log units below the quartz fayalite magnetite buffer these measurements suggest that h2 does not combust at the surface of the lake and that h2 is kinetically inert in the gas aerosol plume retaining the signature of the high temperature chemical equilibrium reached in the lava lake we also observe a cyclical variation in the h2 so2 ratio with a period of 10 min these cycles correspond to oscillatory patterns of surface motion of the lava lake that have been interpreted as signs of a pulsatory magma supply at the top of the magmatic conduit

electrochemical sensors applied to pollution monitoring measurement error and gas ratio bias a volcano plume case study there is an increasing scientific interest in the use of miniature electrochemical sensors to detect and quantify atmospheric trace gases this has led to the development of multi gas systems applied to measurements of both volcanic gas emissions and urban air pollution however such measurements are subject to uncertainties introduced by sensor response time a critical issue that has received limited attention to date here a detailed analysis of output from an electrochemical so2 sensor and two h2s sensors contrasting in their time responses and cross sensitivities demonstrates how instrument errors arise under the conditions of rapidly fluctuating by dilution gas abundances leading to scatter and importantly bias in the reported gas ratios in a case study at miyakejima volcano japan electrochemical sensors were deployed at both the crater rim and downwind locations thereby exposed to rapidly fluctuating and smoothly varying plume gas concentrations respectively discrepancies in the h2s so2 gas mixing ratios derived from these measurements are attributed to the sensors differing time responses to so2 and h2s under fluctuating plume conditions with errors magnified by the need to correct for so2 interference in the h2s readings development of a sensor response model that reproduces sensor t90 behaviour the time required to reach 90 of the final signal following a step change in gas abundance during calibration enabled this measurement error to be simulated numerically the sensor response times were characterised as so2 sensor t90 13 s h2s sensor without interference t90 11 s and h2s sensor with interference t90 20 s to h2s and 32 s to so2 we show that a method involving data integration between periods of episodic plume exposure identifiable in the sensor output yields a less biased h2s so2 ratio estimate than that derived from standard analysis approaches for the miyakejima crater rim dataset this method yields highly correlated h2s and so2 abundances r2 0 99 and the improved crater rim data analysis combined with downwind measurements yields h2s so2 0 11 0 01 our analysis has significant implications for the reliance that can be placed on multi gas derived gas ratios whether for volcanological or other purposes in the absence of consideration of the complexities of sensor response times

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

magma hydrothermal system interaction inferred from volcanic gas measurements obtained during 2003 2008 at meakandake volcano hokkaido japan phreatic eruptions occurred at the meakandake volcano in 1988 1996 1998 2006 and 2008 we conducted geochemical surveillance that included measurements of temperature so2 emission rates and volcanic gas composition from 2003 to 2008 at the nakamachineshiri nm northwest nw and akanuma ak fumarolic areas and the 96 1 vent where historical eruptions had occurred the elemental compositions of the gases discharged from the different areas are similar compared with the large variations observed in volcanic gases discharged from subduction zones all the gases showed high apparent equilibrium temperatures suggesting that all these gases originated from a common magmatic gas the gases discharged from each area also exhibited different characteristics which are probably the results of differences in the conditions of meteoric water mixing quenching of chemical reactions and vapor liquid separation the highest apparent equilibrium temperatures about 500 c were observed in the case of nw fumarolic gases despite the low outlet temperature of about 100 c at these fumaroles since the nw fumaroles were formed as a result of the 2006 phreatic eruption the high temperature gas supply to the nw fumarole suggests that the phreatic eruption was caused by the ascent of high temperature magmatic gases the temperatures compositions and emission rates of the nm and 96 1 gases did not show any appreciable change after the 2006 eruption indicating that each fumarolic system had a separate magmatic hydrothermal system the temperatures compositions and emission rates of the nm fumarolic gases were apparently constant and these fumaroles are inferred to be formed by the evaporation of a hydrothermal system with a constant temperature of about 300 c the 96 1 gas compositions showed large changes during continuous temperature decrease from 390 to 190 c occurred from 2003 to 2008 but the sulfur gas emission rates were almost constant at about four tons day at the 96 1 vent the so2 h2s ratio decreased while the h2 h2o ratio remained almost constant this was probably caused by the rock buffer controlled chemical reaction during the temperature decrease

grain size distribution function of polymodal sediments in hydraulic and aeolian environments and numerical partitioning of the sedimentary components most continental sediments are polymodal composed of overlapping components of which the grain size generally obeys some type of natural distribution the grain size components and their function types can be determined from frequency and cumulative curve plots in order to define the function formula of the grain size distribution the function parameters can be estimated by fitting a defined function formula to the measured grain size data of the sample which simultaneously achieves numerical partitioning of the sedimentary components genetic analysis of grain size components of hydraulic and aeolian sediments demonstrates the following environmental implications fluvial sediment is composed of isolated saltation and suspension components the sediments in closed lake basins are dominated by a suspension silt clay component with a small proportion of saltation sand the fine sand component makes up the majority of desert sand overlapping with a small proportion of fine dust aeolian loess is composed of two overlapping components a short suspension time silt component and a long suspension time fine component aeolian material in the north pacific deep sea sediments is dominated by long suspension time fine dust the fine component in aeolian sediments shows a consistent grain size distribution and genetic connection from the desert sand loess of northern china to the north pacific ocean which is mainly transported by westerly winds and is dispersed in the atmosphere forming a background dust c 2002 elsevier science b v all rights reserved