application of stochastic simulation to co2 flux from soil mapping and quantification of gas release 1 conditional sequential gaussian simulations sgs have been applied for the first time to the study of soil diffuse degassing from different volcanic and nonvolcanic systems the application regards five data sets of soil co2 fluxes measured with the accumulation chamber methodology at the volcanic areas of solfatara of pozzuoli italy vesuvio cone italy nisyros greece and horseshoe lake california and at the nonvolcanic degassing area of poggio dell olivo italy the sgs algorithm was used to generate 100 realizations of co2 flux for each area probabilistic summaries of these simulations together with the information given by probability plots were used 1 to draw maps of the probability that co2 fluxes exceed thresholds specific for a background flux i e to define the probable extension of the degassing structures 2 to calculate the total co2 output and 3 to quantify the uncertainty of the estimation the results show that the sgs is a suitable tool to model soil diffuse degassing producing realistic images of the distribution of the co2 fluxes that honor the histogram and variogram of the original data moreover the relation between the sample design and the uncertainty of estimation was investigated leading to an empirical relation between uncertainty and the sampling density that can be useful for the planning of future co2 flux surveys

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

fumarolic and diffuse soil degassing west of mount epomeo ischia italy abstract fumarolic fluid compositions and diffuse soil emissions of hydrothermal fluids of the donna rachele area 0 86 km 2 western flank of mt epomeo ischia island have been studied in order to develop a conceptual geochemical model of the hydrothermal system the degassing area was mapped and the total release of hydrothermal gas and heat associated with the diffuse emission of hydrothermal fluids was estimated a mesostructural study was carried out in order to investigate the relations between the brittle structures and the main pathways of the uprising vapor the fumarolic compositions are typical of hydrothermal fluids and water 99 represents the major component all gas species in the h 2 o h 2 co ch 4 co 2 h 2 s system are close to equilibrium concentrations at temperatures of 300 c and at redox conditions slightly more oxidizing than expected the compositions of the donna rachele fumarolic gas approach the pure liquid equilibrium composition this indicates a high fraction of separated vapor and suggests the presence of a highly energetic hydrothermal system at depth the pure liquid equilibrium compositions of the donna rachele fumaroles along with the historical records of shallow seismicity the explosion of a well in 1995 the occurrence of intense acoustic phenomena and of shallow wells discharging vapor indicate that the internal pressure of the hydrothermal system is occasionally larger than the hydrostatic pressure to quantify the energy dissipated in the donna rachele area by the emission of fumarolic fluids the hydrothermal diffuse degassing was studied by means of 336 soil co 2 flux measurements the highest co 2 fluxes were measured in hydrothermally altered areas along the faults that border mt epomeo structural data indicate that the vapor rises up along nw se striking normal faults related to gravity induced stresses and affecting highly fractured lavas the older faults which are related to the mt epomeo resurgence act as a permeability barrier and bound the donna rachele diffuse degassing structure the total hydrothermal co 2 output was estimated to be 9 t d 1 assuming that the h 2 o co 2 ratio of the fluids that feed the diffuse degassing is the same as that of fumarolic effluents the calculated heat flux is 40 mw this value which represents an important energy release is only a part of the total thermal energy release of ischia where other fumarolic areas occur the results obtained at ischia indicate the importance of thermal energy released by diffuse degassing structures in the energy balance of quiescent volcanoes values of the thermal energy release from the ischia hydrothermal system are comparable with those estimated on other quiescent volcanoes

fumarole emissions at mount st helens volcano june 1980 to october 1981 degassing of a magma hydrothermal system abstract this study is an investigation of the chemical changes in the mount st helens fumarole gases up to october 1981 the sources of the fumarole gases and the stability of gas species in the shallow magma system these problems are investigated by calculations of element compositions thermodynamic equilibria and magmatic volatile hydrothermal steam mixing models the fumarole gases are treated as mixtures of magmatic volatiles and hydrothermal steam formed by magma degassing and boiling of local waters in a dryout zone near conduit and dome magma the magmatic volatile fraction is significant in fumaroles with temperatures in excess of the magma cracking temperature 700 c i e the temperature below which cracking is induced by thermal stresses during cooling and solidification linear composition changes of the fumarole gases over time appear to be the result of a steady decline in the magmatic volatile mixing fraction which may be due to the tapping of progressively volatile depleted magma the maximum proportion of hydrothermal steam in the fumaroles rose from about 25 35 in september 1980 to around 50 70 by october 1981 fractional degassing of magmatic co 2 and sulfur also contributed to the chemical changes in the fumarole gases the steady chemical changes indicate that replenishment of the magma system with undegassed magma was not significant between september 1980 and september 1981 extrapolations of chemical trends suggest that fumarole gases emitted at the time of formation of the first dome in mid june 1980 were more enriched in a magmatic volatile fraction and contained a minimum of 9 co 2 calculations show h 2 s is the predominant sulfur species in mount st helens magma below depths of 200 m rapid release of gases from magma below this depth is a plausible mechanism for producing the high h 2 s so 2 observed in mount st helens plumes during explosive eruptions this study suggests that dacite andesite volcanos may emit gases richer in co 2 during the earlier episodes of an eruptive cycle and burden the atmosphere with much more h 2 s than so 2 during explosive eruptions

temporal variations of gas compositions of fumaroles in the tatun volcano group northern taiwan article i nfo he 4 he geochemical monitoring hydrothermal activity is common in the tatun volcano group of northern taiwan helium isotopic compositions of fumarolic samples show that mantle component occupies more than 60 in the previous study along with recent seismic results a magma reservoir is inferred to have existed beneath the area of da you keng where fumarolic venting is the most active in tatun volcano group progressive increases of hcl concentrations and so2 h2s ratio in fumaroles from da you keng have been observed since august 2004 the hcl concentration changed from almost the detection limit to thousands of ppm even up to 30 000 ppm so2 h2s ratios varied from almost 0 to 3 hence so2 became the dominated s species in this area these variations were accompanied by rising temperature of fumaroles in the tatun volcano group especially in the area of da you keng from boiling point to 131 c meanwhile 3

diffuse emission of carbon dioxide methane and helium 3 from teide volcano tenerife canary islands diffuse emission of co2 ch4 and he was investigated in the summit crater of teide volcano tenerife canary islands the results indicate that teide volcano releases abundant co2 not only from its active crater but also from its flanks as diffuse soil emanations the spatial distribution of these emanations correlates quite closely with that of geothermal anomalies and manifestations our flux measurements indicate a total output of 380 ton day 1 of co2 and 1 6 on day 1 of ch4 by diffuse degassing from the he co2 ratios and the co2 flux we estimate a diffuse he flux of 0 052 mol year 1 isotopic analysis of carbon in soil gas samples from sites of high soil co2 flux indicates a magmatic origin for the co2 also reported by high he 4he ratios of 5 50 and 5 87 ra the origin of methane is more uncertain with low 13c values suggesting a biogenic contribution

warm core vortex amplification over land abstract a convectively generated mesoscale vortex that was instrumental in initiating and organizing five successive mesoscale convective systems over a period of three days is documented two of these convective systems were especially intense and resulted in widespread heavy rain with localized flooding based upon radar and satellite data the detectable size of the vortex became much larger following the strong convective developments nearly tripling its initial diameter over its three day life cycle during nighttime when convection typically intensified within the vortex movement of the system tended to slow following dissipation of the convection in the morning the daytime movement accelerated cross sections of potential vorticity taken through the vortex center clearly show a maximum at midlevels and a well defined minimum directly above the vortex and the potential vorticity maximum were essentially colocated and the system was nearly axisymmetric in the vertical over the three day life

seismo geochemical variations in sw taiwan multi parameter automatic gas monitoring results gas variations of many mud volcanoes and hot springs distributed along the tectonic sutures in southwestern taiwan are considered to be sensitive to the earthquake activity therefore a multi parameter automatic gas station was built on the bank of one of the largest mud pools at an active fault zone of southwestern taiwan for continuous monitoring of co2 ch4 n2 and h2o the major constituents of its bubbling gases during the year round monitoring from october 2001 to october 2002 the gas composition especially ch4 and co2 of the mud pool showed significant variations taking the co2 ch4 ratio as the main indicator anomalous variations can be recognized from a few days to a few weeks before earthquakes and correlated well with those with a local magnitude 4 0 and local intensities 2 it is concluded that the gas composition in the area is sensitive to the local crustal stress strain and is worthy to conduct real time monitoring for the seismo geochemical precursors

long time variation of soil co2 fluxes at the summit crater of vulcano italy here we report the first continuous data of geochemical parameters acquired directly from the active summit crater of vulcano this approach provides a means to better investigate deep geochemical processes associated with the degassing system of vulcano island in particular we report on soil co2 fluxes from the upper part of vulcano a closed conduit volcano from september 2007 to october 2010 large variations in the soil co2 and plume so2 fluxes order of magnitude coinciding with other discontinuous geochemical parameters co2 concentrations in fumarole gas and physical parameters increase of shallow seismic activity and fumarole temperatures have been recorded the results from this work suggest new prospects for strengthening geochemical monitoring of volcanic activity and for improving the constraints in the construction of a geochemical model this being a necessary condition to better understand the functioning of volcanic systems

seismogenic stress field beneath the tatun volcano group northern taiwan article i nfo the tatun volcano group tvg represents the main volcanic center in northern taiwan and based on various observations it is considered a potentially active volcano tvg has been monitored since 2003 by a seismic network that consists of eight stations equipped with three component short period and broadband seismometers in this study we use waveform data of high frequency earthquakes in order to investigate the stress field orientation beneath the tvg area the focal mechanisms of 35 selected events have been derived using p wave polarities and amplitude ratios assuming a double couple source these fault plane solutions and various subsamples derived from them were subsequently inverted for the best fitting stress tensor using a linear inversion method the results show stress homogeneity beneath tvg for depths larger than 3 km while the stress tensor is characterized by a subvertical 1 and a subhorizontal nw se trending 3 axis consistent with the regional stress field in northern taiwan on the other hand chihsinshan which is an area of vigorous hydrothermal activity exhibits a localized stress field with horizontal nw se trending 3 axis and ne sw trending horizontal 1 such an axes orientation is likely to be causing opening of microcracks and thus favour the ascent and circulation of fluids in the upper crust shear wave splitting measurements seem to confirm these results showing fast polarization directions along nne ne subparallel to the main fracture system in tvg shear wave anisotropy averages about 2 9 and is probably caused by an anisotropic volume of fluid saturated cracks within the upper 2 5 km of the crust

preliminary analysis of volcanoseismic signals recorded at the tatun volcano group northern taiwan 1 the tatun volcano group lies at the northern tip of taiwan only 15 km north of the capital taipei a seismic array consisting of 5 stations equipped with both broadband and short period sensors was installed in 2003 in order to monitor the seismic activity of the area it recorded a variety of events including common volcano tectonic earthquakes and volcanoseismic signals like tornillos short duration monochromatic events 10 15 s and long duration spasmodic bursts 15 min an analysis of the complex frequencies of the tornillo monochromatic signals shows that q values are of the order of several hundreds based on the model of a fluid filled crack such q values can result from the oscillations of a crack containing a misty or dusty gas these observations put into doubt the long standing suggestion that the tatun volcanoes are extinct and prompt for a thorough assessment of the volcanic hazard for this area

fluid geochemistry and soil gas fluxes co2 ch4 h2s at a promissory hot dry rock geothermal system the acoculco caldera mexico abstract the acoculco caldera has been recognized by the mexican federal electricity company cfe as a hot dry rock geothermal system hdr and could be a potential candidate for developing an enhanced geothermal system egs apart from hydrothermally altered rocks geothermal manifestations within the acoculco caldera are scarce close to ambient temperature bubbling springs and soil degassing are reported inside the caldera while a few springs discharge warm water on the periphery of the caldera in this study we infer the origin of fluids and we characterize for the first time the soil degassing dynamic chemical and isotopic 18o d analyses of spring waters indicate a meteoric origin and the dissolution of co2 and h2s gases while gas chemical and isotopic compositions n2 he 3he 4he 13c 15n reveal a magmatic contribution with both morb and arc type signatures which could be explained by an extension regime created by local and regional fault systems gas geothermometry results are in agreement with temperature measured during well drilling 260 c 300 c absence of well developed water reservoir at depth impedes re equilibration of gases upon surface a multi gas flux survey including co2 ch4 and h2s measurements was performed within the caldera using the graphical statistical analysis gsa approach co2 flux measurements were classified in two populations population a representing 95 of measured fluxes is characterized by low values mean 18 g m 2 day 1 while the remaining 5 fluxes belonging to population b are much higher mean 5543 g m 2 day 1 this low degassing rate probably reflects the low permeability of the system a consequence of the intense hydrothermal alteration observed in the upper 800 m of volcanic rocks an attempt to interpret the origin and transport mechanism of these fluxes is proposed by means of flux ratios as well as by numerical modeling measurements with co2 ch4 and co2 h2s flux ratios similar to mass ratios of sampled gases were considered as reflecting advective transport a numerical model of co2 migration in the subsoil system under fully water and gas saturated conditions was performed using the tough2 code in order to reproduce semi quantitatively field measurements the main results show that high flux values produced by advective geothermal degassing can be very localized and that low and heterogeneous permeability conditions can induce low advective co2 flux values therefore in this case the populations discriminated by the gsa method should not be interpreted in terms of origin and or transport mechanism but rather in terms of permeability conditions

numerical simulation of an intense squall line during 10 11 june 1985 pre storm part ii rear inflow surface pressure perturbations and stratiform precipitation abstract an intense rear inflow jet surface pressure perturbations and stratiform precipitation associated with a squall line during 10 11 june 1985 are examined using a three dimensional mesoscale nested grid model it is found that the large scale baroclinity provides favorable and deep rear to front flow within the upper half of the troposphere and the mesoscale response to convective forcing helps enhance the trailing extensive rear inflow however latent cooling and water loading are directly responsible for the generation of the descending portion of the rear inflow the role of the rear inflow is generally to produce convergence ahead and divergence behind the system and thus assist the rapid acceleration of the leading convection when the prestorm environment is convectively favorable and the rapid dissipation of the convection when encountering unfavorable conditions in this case study the rear inflow jet appears to have caused the splitting of the surface wake low as well as the organized

heat flux from magmatic hydrothermal systems related to availability of fluid recharge abstract magmatic hydrothermal systems are of increasing interest as a renewable energy source surface heat flux indicates system resource potential and can be inferred from soil co 2 flux measurements and fumarole gas chemistry here we compile and reanalyze results from previous co 2 flux surveys worldwide to compare heat flux from a variety of magma hydrothermal areas we infer that availability of water to recharge magmatic hydrothermal systems is correlated with heat flux recharge availability is in turn governed by permeability structure lithology rainfall topography and perhaps unsurprisingly proximity to a large supply of water such as the ocean the relationship between recharge and heat flux interpreted by this study is consistent with recent numerical modeling that relates hydrothermal system heat output to rainfall catchment area this result highlights the importance of recharge as a consideration when evaluating hydrothermal systems for electricity generation and the utility of co 2 flux as a resource evaluation tool

geochemical evidence of the renewal of volcanic activity inferred from co2 soil and so2 plume fluxes the 2007 stromboli eruption italy on 27 february 2007 a new eruption occurred on stromboli which lasted until 2 april it was characterized by effusive activity on the sciara del fuoco and by a paroxysmal event 15 march this crisis represented an opportunity for us to refine the model that had been developed previously 2002 2003 eruption and to improve our understanding of the relationship between the magmatic dynamics of the volcano and the geochemical variations in the fluids in particular the evaluation of the dynamic equilibrium between the volatiles co2 and so2 released from the magma and the corresponding fluids discharged from the summit area allowed us to evaluate the level of criticality of the volcanic activity one of the major accomplishments of this study is a 4 year database of summit soil co2 flux on the basis of which we define the thresholds low medium high for this parameter that are empirically based on the natural volcanological evolution of stromboli the so2 fluxes of the degassing plume and the co2 fluxes emitted from the soil at pizzo sopra la fossa are also presented it is noteworthy that geochemical signals of volcanic unrest have been clearly identified before during and after the effusive activity these signals were found almost simultaneously in the degassing plume so2 flux and in soil degassing co2 flux at the summit although the two degassing processes are shown to be clearly different the interpretation of the results will be useful for future volcanic surveillance at stromboli

carbon dioxide emissions from soils at hakkoda north japan 1 a soil gas and co2 efflux survey was carried out at hakkoda north japan to investigate the spatial distribution and origin of the gas which caused the accidental death of three japanese soldiers on 12 july 1997 in the study area no fumarolic and or thermal activity is observed chemical composition of the gas from areas with high co2 effluxes 5 000 g m 2 d 1 and high co2 contents 15 vol indicate a strong deep sourced contribution for co2 whereas air and or air saturated water is suggested for the rest of the discharged gases which are mainly released from a shallow aquifer isotopic analysis of soil gas and hot spring discharges suggests a combination of magmatic degassing and thermal decarbonation with magmatic degassing being the main contributior to the high co2 emission approximately 74 t d 1 of deep seated magmatic plus thermal decarbonation origin co2 were estimated to contribute to the total output of co2 from this area

diffuse co2 emission rate from pululahua and the lake filled cuicocha calderas ecuador abstract we report herein the first results of two soil co 2 efflux surveys carried out at cuicocha lake filled and pululahua caldera volcanic systems ecuador a total of 172 and 217 soil co 2 efflux measurements were taken at the surface environment of pululahua and cuicocha calderas respectively by means of the accumulation chamber method during the summer of 2006 to constrain the total co 2 output from the studied area soil co 2 efflux values ranged from non detectable up to 48 5 and 141 7 g m 2 d 1 for cuicocha and pululahua calderas respectively in addition probability graphs were used to distinguish the existence of different geochemical populations sequential gaussian simulation was used to construct an average map for 100 simulations and to compute the total co 2 emission at each studied area 106 and 270 t d 1 metric tons per day for cuicocha 13 3 km 2 and pululahua 27 6 km 2 volcanoes respectively

compositions and flux of soil gas in liu huang ku hydrothermal area northern taiwan abstract soil co 2 flux has been considered a useful proxy to remotely monitor volcanic activity in a hydrothermal area within a safe distance the liu huang ku lhk area which is close to the taipei basin and many existing active fumaroles and hot springs was chosen for the first systematic soil gas study in a hydrothermal area of taiwan in 2004 and 2006 the soil co 2 flux was measured by the closed chamber method with a non dispersive infrared detector soil co 2 emission rate was estimated 19 8 0 2 t day 1 and 582 t km 2 day 1 in 2004 and 22 4 0 2 t day 1 and 659 t km 2 day 1 in 2006 respectively these values are close to those reported for other active high co 2 flux hydrothermal areas of the world it implies that magmatic gases are actively degassing from subsurface in northern taiwan helium and carbon isotopic data reveal that soil gas in lhk is mainly derived from the mantle and is mixed with a small amount of crustal and air components the abundance of soil co 2 shows a positive correlation with the 3 he 4 he ratios and total sulfur contents which are considered as magmatic sensitive indicators for the fumarolic samples therefore soil co 2 could be used as a good proxy for future monitoring of magmatic activity in this area

soil co2 flux in hydrothermal areas of the tatun volcano group northern taiwan abstract we measured soil co2 flux in the representative hydrothermal areas of the tatun volcano group tvg to better understand the volcano s dynamic nature and to estimate its soil co2 degassing output results show that the average soil co2 fluxes obtained at da you keng dyk geng tze ping gtp she haung ping shp and tatun natural park tnp were 128 g m 2 d 1 518 g m 2 d 1 420 g m 2 d 1 and 25 g m 2 d 1 respectively the range is comparable to other active volcanic hydrothermal areas in the world along with liu huang ku lhk where the soil co2 flux is known the total soil co2 output from measured areas is evaluated at 82 t d 1 furthermore a first total soil co2 output from the whole hydrothermal areas of the tvg is roughly estimated at 113 t d 1 which includes 15 t d 1 mantle contribution considering the mantle derived co2 flux and h2o co2 ratio of fumarolic gas thermal energy associated with the diffuse degassing at the tvg hydrothermal area is estimated at 8 2 mw carbon 13c and helium 3he 4he isotopic ratios of soil samples of the studied areas ranged from 4 4 to 6 7 and 2 45 to 6 98 ra respectively the extent of air involvement in the soil degassing system as constrained by the helium and carbon isotopic compositions provides essential information for depicting regional degassing features of the hydrothermal areas

soil co2 flux baseline in an urban monogenetic volcanic field the auckland volcanic field new zealand the auckland volcanic field avf is a dormant monogenetic basaltic field located in auckland new zealand though soil gas co2 fluxes are routinely used to monitor volcanic regions there have been no published studies of soil co2 flux or soil gas co2 concentrations in the avf to date or many other monogenetic fields worldwide we measured soil gas co2 fluxes and soil gas co2 concentrations in 2010 and 2012 in varying settings seasons and times of day to establish a baseline soil co2 flux and to determine the major sources of and controlling influences on auckland s soil co2 flux soil co2 flux measurements varied from 0 to 203 g m 2 day 1 with an average of 27 1 g m 2 day 1 higher fluxes were attributed to varying land use properties e g landfill using a graphical statistical approach two populations of co2 fluxes were identified isotope analyses of 13co2 confirmed that the source of co2 in the avf is biogenic with no volcanic component these data may be used to assist with eruption forecasting in the event of precursory activity in the avf and highlight the importance of knowing land use history when assessing soil gas co2 fluxes in urban environments

precursory diffuse co2 and h2s emission signatures of the 2011 2012 el hierro submarine eruption canary islands 1 on october 12 2011 a submarine eruption began 2 km off the coast of la restinga south of el hierro island co2 and h2s soil efflux were continuously measured during the period of volcanic unrest by using the accumulation chamber method at two different geochemical stations hie01 and hie07 recorded co2 and h2s effluxes showed precursory signals that preceded the submarine eruption beginning in late august the co2 efflux time series started increasing at a relatively constant rate over one month reaching a maximum of 19 gm 2d 1 one week before the onset of the submarine volcanic eruption the h2s efflux time series at hie07 showed a pulse in h2s emission just one day before the initiation of the submarine eruption reaching peak values of 42 mg m 2 d 1 10 times the average h2s efflux recorded during the observation period since co2 and h2s effluxes are strongly influenced by external factors we applied a multiple regression analysis to remove their contribution a statistical analysis showed that the long term trend of the filtered data is well correlated with the seismic energy we find that these geochemical stations are important monitoring sites for evaluating the volcanic activity of el hierro and that they demonstrate the potential of applying continuous monitoring of soil co2 and h2s efflux to improve and optimize the detection of early warning signals of future volcanic unrest episodes at el hierro continuous diffuse degassing studies would likely prove useful for monitoring other volcanoes during unrest episodes

post collisional magmatism around northern taiwan and its relation with opening of the okinawa trough being part of an active mountain belt formed by oblique collision of the luzon arc with asia northern taiwan and the offshore islets are marked by a series of latest pliocene quaternary volcanoes whose eruptions have been conventionally ascribed to westward propagation of the ryukyu volcanic arc on the basis of new geochemical data along with supporting geologic and geophysical evidence we propose instead that this young volcanism resulted from post collisional lithospheric extension in the northern taiwan mountain belt and the mantle source regions involved in the melt generation have been significantly modified by the nearby ryukyu subduction related processes magmas thus produced through the northeast to the southwest in the northern taiwan volcanic zone ntvz vary from low k to calc alkaline and then shoshonitic compositions such a spatial geochemical variation characterized by southwestward increase in enrichments of potassium and incompatible trace elements runs subparallel to the southwestern part of the present day ryukyu trench the geochemical variation that can be explained by southwestward decrease in degrees of partial melting of the mantle sources is reconciled with a southwestward weakening extensional regime observed in the ntvz the post collisional extension in northern taiwan furthermore might have played a role in reactivation of the opening in the middle okinawa trough and gave way to its rapid southwestward propagation with associated development of the ryukyu subduction zone west of124oe this nascent subduction in turn resulted in abundant submarine volcanoes which delineate an embryo volcanic front along the southern margin of the trough therefore the southwestern okinawa trough is not a fore arc basin as had been previously alleged but represents an atypical back arc basin which developed broadly synchronously or prior to its arc trench system in this particular collision extension subduction tectonic environment 1999 elsevier science b v all rights reserved

geographical distribution of 3he 4he ratios in japan implications for arc tectonics and incipient magmatism the 3he 4he and 4he 20ne ratios of 115 natural gas samples including various types of gases from volcanoes hot springs mineral springs water wells petroleum fields and natural gas fields were measured using a mass spectrometer the observed 3he 4he and 4he 20ne ratios range from 7 47 10 8 to 9 65 10 6 and from 0 26 to 1100 respectively the 3he 4he ratios reflect well the geotectonic structure of the japanese islands in northeastern ne japan there is a clear geographical difference in the 3he 4he ratios between the frontal arc forearc and volcanic arc back arc regions lower ratios were found in the trench side region and higher ratios in the back arc side this result suggests that the mantle derived helium in the volcanic arc region is associated with the diapiric uprise of a magma lower 3he 4he ratios in the frontal arc region may be due to radiogenic he produced by radioactive decay of u and th in the crustal and sedimentary rocks in southwestern sw japan there is no clear geographical contrast in the 3he 4he ratios some samples in the frontal arc region show quite high 3he 4he ratios the tendency of the 3he 4he ratios agrees with the distribution of terrestrial heat flow data and reflects geotectonic structures different from ne japan the high 3he 4he ratios observed in the frontal arc region in sw japan may be indicative of renewed or incipient magmatism due to a descending young and warm slab

soil co2 emissions as a proxy for heat and mass flow assessment taupō volcanic zone new zealand the quantification of heat and mass flow between deep reservoirs and the surface is important for understanding magmatic and hydrothermal systems here we use high resolution measurement of carbon dioxide flux co2 and heat flow at the surface to characterize the mass co2 and steam and heat released to the atmosphere from two magma hydrothermal systems our soil gas and heat flow surveys at rotokawa and white island in the taup volcanic zone new zealand include over 3000 direct measurements of co2 and soil temperature and 60 carbon isotopic values on soil gases carbon dioxide flux was separated into background and magmatic hydrothermal populations based on the measured values and isotopic characterization total co2 emission rates co2 of 441 84 t d 1 and 124 18 t d 1 were calculated for rotokawa 2 9 km2 and for the crater floor at white island 0 3 km2 respectively the total co2 emissions differ from previously published values by 386 t d 1 at rotokawa and 25 t d 1 at white island demonstrating that earlier research underestimated emissions by 700 rotokawa and 25 white island these differences suggest that soil co2 emissions facilitate more robust estimates of the thermal energy and mass flux in geothermal systems than traditional approaches combining the magmatic hydrothermal sourced co2 emission constrained using stable isotopes with reservoir h2o co2 mass ratios and the enthalpy of evaporation the surface expression of thermal energy release for the rotokawa hydrothermal system 226 mwt is 10 times greater than the white island crater floor 22 5 mwt

analysis of a small vigorous mesoscale convective system in a low shear environment part ii evolution of the stratiform precipitation and mesoscale flows abstract the evolution of the mesoscale flow and precipitation distribution are investigated for a small mesoscale convective system mcs that evolved in a nearly barotropic environment exhibiting moderate instability and weak wind shear observations primarily from a single doppler radar detail the growth of the mcs from the merger of several clusters and lines of vigorous convective cells into a mature state consisting of a weaker convective line trailed by an expanding stratiform precipitation region analysis of radar reflectivity reveals that this stratiform region formed in situ in the presence of weak mesoscale updraft as decaying convective cores coalesced rather than through rearward advection of ice particles directly from the convective region in the absence of sufficient low level shear the mcs collapsed rapidly as it assumed the structure of the archetypal convective line and trailing stratiform precipitation region velocity azimuth displays reveal mesoscale updrafts of about 70 cm s 1 d

volatile emissions and gas geochemistry of hot spring basin yellowstone national park usa abstract we characterize and quantify volatile emissions at hot spring basin hsb a large acid sulfate region that lies just outside the northeastern edge of the 640 ka yellowstone caldera relative to other thermal areas in yellowstone hsb gases are rich in he and h2 and mildly enriched in ch4 and h2s gas compositions are consistent with boiling directly off a deep geothermal liquid at depth as it migrates toward the surface this fluid and the gases evolved from it carries geochemical signatures of magmatic volatiles and water rock reactions with multiple crustal sources including limestones or quartz rich sediments with low k u or 40 ar 4 he variations in gas chemistry across the region reflect reservoir heterogeneity and variable degrees of boiling gas geothermometer temperatures approach 300 c and suggest that the reservoir feeding hsb is one of the hottest at yellowstone diffuse co2 flux in the western basin of hsb as measured by accumulation chamber methods is similar in magnitude to other acid sulfate areas of yellowstone and is well correlated to shallow soil temperatures the extrapolation of diffuse co2 fluxes across all the thermal altered area suggests that 410 140 t d 1 co2 are emitted at hsb vent emissions not included diffuse fluxes of h2s were measured in yellowstone for the first time and likely exceed 2 4 t d 1 at hsb comparing estimates of the total estimated diffuse h2s emission to the amount of sulfur as so42 in streams indicates 50 of the original h2s in the gas emission is lost into shallow groundwater precipitated as native sulfur or vented through fumaroles we estimate the heat output of hsb as 140 370 mw using co2 as a tracer for steam condensate but not including the contribution from fumaroles and hydrothermal vents overall the diffuse heat and volatile fluxes of hsb are as great as some active volcanoes but they are a small fraction 1 3 for co2 2 8 for heat of that estimated for the entire yellowstone system

diffuse soil emission of hydrothermal gases co2 ch4 and c6h6 at solfatara crater campi flegrei southern italy abstract measurements of soil fluxes of hydrothermal gases with special emphasis on c 6 h 6 as well as chemical composition of mono aromatic compounds in fumaroles and air were carried out in april 2012 at the solfatara crater campi flegrei southern italy to investigate the distribution and behavior of these species as they migrate through the soil from their deep source to the atmosphere soil fluxes of co 2 ch 4 and c 6 h 6 exhibit good spatial correlation suggesting that diffuse degassing is mainly controlled by local fractures the calculated total output of diffuse c 6 h 6 from solfatara is 0 10 kg day 1 whereas fluxes of co 2 and ch 4 are 79 10 3 and 1 04 kg day 1 respectively a comparison between soil gas fluxes and fumarole composition reveals that within the crater soil ch 4 is significantly affected by oxidation processes which are more efficient for low gas fluxes being dependent on the residence time of the uprising hydrothermal gases at shallow depth benzene degradation mainly proceeding through oxidation via benzoate seems to be strongly controlled by the presence of a shallow so 4 2 rich aquifer located in the central and southwestern sectors of the crater suggesting that the process is particularly efficient when so 4 2 acts as terminal electron acceptor so 4 reduction relatively high c 6 h 6 c 7 h 8 ratios typical of hydrothermal fluids were measured in air close to the main fumarolic field of solfatara crater here c 6 h 6 concentrations whose detection limit is 0 1 g m 3 are more than one order of magnitude higher than the limit value for ambient air 5 g m 3 this suggests that hydrothermal fluids have a strong impact on air quality in the immediate surroundings of the fumarolic vents significant concentrations of endogenous mono aromatics were also detected in air samples collected from the northern and western sides of the crater where these gas compounds are mostly fed by diffuse degassing through the crater bottom soil

origin of carbon in fumarolic gas from island arcs abstract we have measured 3 he 4 he ratios 13c values and co 2 3 he ratios of fumaroles and hot spring gases in three volcanic areas in japan the 3 he 4 he ratios 13c values and co 2 3 he ratios vary from 02 05 ratm 9 7 to 2 7 and from 7 74 109 to 1 18 1011 respectively based on these data and those in the literature we present the first quantitative estimates of the upper mantle sediment and limestone including slab components in co2 of volcanic and hydrothermal fluids from subduction zones taking compiled c isotopic data of limestone and organic sediment assuming that the co 2 3 he ratio and 13c value of mid ocean ridge basalt morb are representative of the upper mantle component and that later isotopic and elemental fractionations are minimal it is possible to deconvole each fraction of c on the basis of simple mixing equations up to 20 of the carbon in high temperature volcanic gases in subduction zones is derived from a morb type source while the major fraction of the gases is attributable to co2 produced by decarbonation of subducted marine limestone and slab carbonate

helium isotope evidence for magmatic gases in lake nyos cameroon we have measured he 4he and 4he 20ne ratios of gas samples collected at lake nyos where a toxic gas disaster occurred on august 21 1986 and at lake monoun in cameroon west africa the he 4he ratios corrected for air contamination are 5 39 5 75 ratm where ratm is the atmospheric ratio of 1 40 10 6 for lake nyos and 3 56 ratm for lake monoun the data suggest a significant contribution of mantle derived helium in these cameroon volcanic crater lakes the origin of co2 gas erupted during lake nyos disaster is inferred to be of magmatic origin based on the high he 4he ratio

the 2002 2003 eruption of stromboli italy evaluation of the volcanic activity by means of continuous monitoring of soil temperature co2 flux and meteorological parameters 1 from december 2002 to july 2003 stromboli volcano was characterized by a new effusive stage of eruption after a period of extraordinary strombolian activity signals recorded in two continuous monitoring stations during the eruption which have already been presented in very recent papers evidenced anomalies in the co2 flux just before the onset of the eruption a more detailed analysis carried out on the data subset acquired during the eruption integrated by daily field observations of the scientific personnel working at the volcanological observatory in stromboli showed that co2 flux and soil temperature are strictly related to volcanic events furthermore the relative minima and maxima of the two parameters showed a strong correlation with wind speed and direction this fact was especially true at the summit station whereas at the coastal sites seasonal and meteorological effects masked the volcanic signal the analysis of the wind data particularly the relationships between wind speed and direction air and soil temperature and local circulation of atmospheric air masses revealed that during the eruption in the summit area of stromboli air movements were not only related to atmospheric circulation but were also significantly affected and in certain cases caused by volcanic activity this conclusion was reached by observing several anomalies such as the discrepancies in the wind direction between the two stations higher air temperatures at the summit site and inversion of direction for wind before and after the reopening of the conduit in a major explosion on 5 april 2003 the relationships found between volcanic activity soil temperatures co2 fluxes and wind speed and direction indicate that soil temperature measurements in an open conduit volcano such as in this case could be used to monitor the level of volcanic activity along with co2 flux furthermore the possible volcanic origin of a peculiar type of air circulation identified in the summit area of stromboli suggests that the separation between volcanic and atmospheric signals might not be obvious requiring monitoring over a wide area rather than a single location

identifying blind geothermal systems with soil co2 surveys abstract diffuse soil co2 flux surveys are a widely applied approach for delineating zones of elevated heat and mass transfer in areas with geothermal surface features including hot springs mud pools and geysers however many geothermal systems are capped by relatively impermeable layers that diminish the surface expression of potential resources present at depth here we report diffuse soil co2 flux survey results with complementary 13co2 values and shallow soil temperatures for the ngatamariki geothermal system taupo volcanic zone new zealand a largely surface blind system in an effort to explore the utility of such data as indicators of magmatic carbon emission in geothermal systems with low co2 flux our results include that 1 the majority 54 of the soil co2 flux measurements are below background levels 15 gco2 m 2 day 1 2 only 5 6 of the shallow 10 cm soil temperatures exceed 30 c and 3 no correlation is present between soil temperature and co2 flux at ngatamariki these results belie the fact that a recently developed geothermal resource is present beneath ngatamariki yet 13co2 values when interpreted in the context of soil gas co2 concentrations demonstrate that the magmatic hydrothermal system beneath ngatamariki can be distinguished from soil zone carbon sources using diffuse soil gas geochemical tracers modeling the ngatamariki co2 system as a simple mixture of geothermal biogenic and atmospheric end members allows for the apportionment of co2 flux at different locations across the field based on these findings we suggest that delineating potential geothermal sites and assessing the relative contributions of mixed fluid end members is possible even with low diffuse co2 flux and limited surface expression of geothermal systems at depth

the oklahoma kansas mesoscale convective system of 10 11 june 1985 precipitation structure and single doppler radar analysis abstract the 10 11 june mesoscale convective system observed in kansas during pre storm is studied using a variety of observations including conventional radar satellite and single doppler radar this storm at maturity consisted of a strong line of convection trailed by a broad region of stratiform rain the pre storm doppler radar observations show that the general airflow pattern is similar to that seen in previously analyzed cases however since the doppler observations were quite extensive in time and space they permit several details of the airflow to be revealed for the first time a rear inflow jet front to rear flow aloft and a mesoscale updraft and downdraft were all present the mesoscale downdraft commenced at the top of the slanted rear inflow jet sublimation and evaporation of hydrometeors in this flow apparently generated the necessary cooling to drive the mesoscale downdraft circulation the intensity and slope of the rear inflow jet varied with location in the storm which apparen

monitoring quiescent volcanoes by diffuse co2 degassing case study of mt fuji japan since the 8th century more than seventeen eruptions have been recorded for the mt fuji volcano with the most recent eruption occurring in 1707 hoei eruption for the past 300 years the volcano has been in a quiescent stage and since the early 1960s has exhibited neither fumarolic nor thermal activity however the number of low frequency earthquakes with a hypocentral depth of 10 20 km increased significantly beneath the northeastern flank of mt fuji in 2000 2001 suggesting a possible resumption of magmatic activity in this study diffuse co2 efflux and thermal surveys were carried out in four areas of the volcano in 2001 2002 in order to detect possible signs of the upward movement of deep magma at all survey points the co2 efflux was below the detection limit with the exception of a few points with biological co2 emission and ground temperatures at a depth of 20 30 cm were below ambient indicating no surface manifestations of gas or heat emission should magma rise into the subsurface the diffuse co2 efflux would be expected to increase particularly along the tectonically weakened lineation on the mt fuji volcano allowing for the early detection of pre eruptive degassing

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

decade time scale variability of ventilation in the north atlantic high precision measurements of bomb radiocarbon in banded corals the first high precision radiocarbon measurements for the upper ocean are presented for banded corals from two sites in the north atlantic ocean the striking dissimilarities between the post 1950 records at bermuda in the sargasso sea and the florida straits in the gulf stream illustrate the different mixing processes in the upper ocean at each site convective overturn associated with 18 degree water formation during late winter in the northern sargasso sea facilitates storage of considerable quantities of bomb radiocarbon at depth which accounts for the damping of the 14c signal at bermuda during the 1960s a multibox isopycnal mixing model is used to estimate the ventilation rate of the upper 700 m of the water column in the sargasso sea from 1950 to 1983 an inverse model is used that is the water mass renewal rate was calculated for the post bomb period in order to satisfy the bomb radiocarbon time history in the corals sea water radiocarbon measurements made during the geosecs 1972 1973 and transient tracers in the ocean 1980 1981 surveys are used to constrain the subsurface radiocarbon values calculated by the model results show that the rate of water mass renewal in the sargasso sea was high during 1963 1964 decreased during the late 1960s and remained low during most of the 1970s the 14c derived record of water mass renewal precedes by about 4 years that derived from isopycnal salinity in the sargasso sea jenkins 1982 illustrating that the coral 14c record is controlled to a large extent by changes in ocean circulation rather than by atmospheric exchange of co2

a diagnostic modelling study of the trailing stratiform region of a midlatitude squall line abstract a kinematic model with continuity equations for sensible heat water vapor cloud water cloud ice rain snow and graupel is used to determine the steady state thermodynamic and microphysical processes associated with the observed mesoscale air motion fields in the trailing stratiform region of the 22 may 1976 oklahoma squall line two versions of the observed air motions are used a low resolution but areally extensive flow pattern derived from the composite sounding data of ogura and liou and a high resolution but less areally extensive flow field obtained from the dual doppler radar analysis of smull and houze model calculations based on the high resolution doppler derived mesoscale air motions show that the location and horizontal scale of the region of most intense stratiform precipitation are determined by the pattern of horizontal transport and fallout of snow and low density graupel particles advected into the stratiform region from the leading line of convective cells the stratiform

anomalous soil co2 degassing in relation to faults and eruptive fissures on mount etna sicily italy the relationships between soil gas emissions and both tectonic and volcano tectonic structures on mt etna have been studied the investigation consisted of soil co2 flux measurements along traverses orthogonal to the main faults and eruptive fissures of the volcano anomalous levels of soil degassing were found mainly in coincidence with faults whereas only 49 of the eruptive fissures were found to produce elevated co2 soil fluxes this result suggests that only zones of strain are able to channel deep gases to the surface according to this hypothesis several previously unknown structures are suggested based on our geochemical data new structural maps of different areas of etna are proposed the soil co2 fluxes observed in this study are higher than those measured in a 1987 study and they are consistent with the higher level of volcanic unrest during the current study

continuous soil co2 and discrete plume so2 measurements at mt etna italy during 1997 2000 a contribution to volcano monitoring continuous monitoring of soil co2 dynamic concentration which is proportional to the co2 flux through the soil was carried out at a peripheral site of mt etna during the period november 1997 september 2000 using an automated station the acquired data were compared with so2 flux from the summit craters measured two to three times a week during the same period the high frequency of data acquisition with both methods allowed us to analyze in detail the time variations of both parameters anomalous high values of soil co2 dynamic concentration always preceded periods of increased flux of plume so2 and these in turn were followed by periods of summit eruptions the variations were modeled in terms of gas efflux increase due to magma ascent to shallow depth and its consequent depressurization and degassing this model is supported by data from other geophysical and volcanological parameters the rates of increase both of soil co2 dynamic concentration and of plume so2 flux are interpreted to be positively correlated both to the velocity of magma ascent within the volcano and to lava effusion rate once magma is erupted at the surface low rates of the increase were recorded before the nine month long 1999 subterminal eruption higher rates of increase were observed before the violent summit eruption of september november 1999 and the highest rates were observed during shorter and very frequent spike like anomalies that preceded the sequence of short lived but very violent summit eruptions that started in late january 2000 and continued until late june of the same year furthermore the time interval between the peaks of co2 and so2 in a single sequence of gas anomalies is likely to be controlled by magma ascent velocity

diffuse co2 efflux from iwojima volcano izu ogasawara arc japan abstract iwojima volcano located on the southernmost part of the izu ogasawara arc is characterized by the extrusion of trachyte or trachy andesite lavas and pyroclastic rocks of holocene and surface thermal manifestations small phreatic explosions have been recorded frequently during the last 100 years with the most recent in 1999 and 2001 in order to elucidate the behavior of volcanic volatiles and to assess the potential activity of this volcano diffuse co 2 efflux co 2 content and 13 c co 2 in soil gas and soil temperature at 30 cm depth were measured at 272 sites in march 2000 112 sites in december 2000 and 40 sites in december 2001 we found that high co 2 efflux values of more than 100 g m 2 day 1 occurred at several locations on motoyama volcano corresponding with high soil temperatures more than 60 c at 30 cm depth region and with areas where co 2 with magmatic 13 c was observed here the magmatic 13 c determined for fumarolic co 2 data ranged from 2 to 3 which is clearly higher than magmatic gas values 8 to 2 typically found in island arc settings around the world however this can be explained in terms of carbon isotope fractionation between calcite and co 2 under subsurface temperature and pressure conditions at iwojima a total efflux of co 2 for iwojima volcano is estimated to be 760 t day 1 with a magmatic contribution of about 450 t day 1 this value is rather high compared with other volcanoes in island arc settings since iwojima has no visible plume almost all volcanic co 2 is released as diffuse efflux through the volcanic edifice

carbon dioxide and radon emissions from the soils of pantelleria island southern italy abstract in the period july 2005 october 2006 several soil gas prospections were performed on the island of pantelleria an active volcanic geothermal system at present in a quiescent state measured parameters were co2 concentrations and 220rn and 222rn activities at 50 cm depth and co2 fluxes from the soil the whole island was covered with a measurement density of 3 5 points km2 for co2 flux and concentration and 1 6 points km2 for rn further three main and seven minor areas of previously ascertained or expected exhalative activity were covered with a measurement density up to 100 points km2 the obtained results ranged from 0 038 to 95 vol for co2 concentration from 10 bq m3 to 164 000 bq m3 from 10 bq m3 to 750 000 bq m3 for 220rn and 222rn activities respectively and from

soil gas profiles as a tool to characterise active tectonic areas the jaut pass example pyrenees france a new method to investigate active tectonic structures using soil gas composition at faults suggests relevant information about regional stress conditions which can be obtained rapidly and at relatively low cost in 1995 we carried out geochemical profiles around the epicentre of the m 5 1 1980 earthquake near arudy in the french pyrenees where the presence of minor fractures is evident in the field and confirmed using satellite spot imagery fractures are conduits facilitating fluid migrations in the crust and are also pathways for the release of deep seated gases to the atmosphere in order to investigate the implication of these fractures in the present deformation i e if they are connected to the hercynian substratum at a depth of about 1800 m soil gases were measured along four traverses crossing the observed structures gases determined were 222rn co2 and 4he each of them for their characteristic source 222rn has essentially a shallow origin due to its short half life whereas co2 is the major soil gas component with a mainly surficial biogenic source however there could additionally be co2 from crustal or mantle degassing which would also be the principal sources of he data analysis clearly reveals anomalous values for each gas at specific positions along the traverses two sets of fractures corresponding to different observed trends are distinguished the one characterised by he anomalies accompanied by other gases and the second with few identified he anomalies the agreement between the geochemical data and the field observations leads us to propose a deformation model for the area studied analogous to a pull apart system located in a right lateral shear zone

the role of convectively generated rear inflow jets in the evolution of long lived mesoconvective systems abstract in this study the structure of convectively generated rear inflow jets and their role in the evolution of long lived mesoconvective systems are investigated through an analysis of idealized three dimensional simulations using a nonhydrostatic cloud model rear inflow jets are generated within these systems in response to the upshear tilting of the convective circulation as the horizontal buoyancy gradients along the back edge of the expanding system create a circulation that draws midlevel air in from the rear within this framework a wide range of rear inflow strengths and structures are produced depending on the magnitude of the ambient convective available potential energy cape and the vertical wind shear in general for environments characterized by weak to moderate vertical wind shear and weak to moderate cape the rear inflow jet descends and spreads along the surface well behind the leading edge of the gust front and the subsequent convective activity becomes weaker however for e

a magmatic source for fumaroles and diffuse degassing from the summit crater of teide volcano tenerife canary islands a geochemical evidence for the 2004 2005 seismic volcanic crisis the present work reports the results of 15 studies of diffuse co2 degassing performed at teide volcano crater canary island spain and the chemical and isotopic compositions of fluids discharged from a fumarolic field located at the top of the volcano as measured between 1991 and 2010 a higher contribution of magmatic gases accompanied by enhanced total diffuse co2 emissions were observed in relation with a seismic crisis that occurred in tenerife island between 2001 and 2005 with the main peak of seismic activity between april and june 2004 a significant pulse in total diffuse co2 emission was observed at the crater of teide up to 26 3 t day 1 in 2001 in december 2003 the chemical composition of the teide fumarole changed significantly including the appearance of so2 an increase in the hcl and co concentrations and in the c2h6 c2h4 and c3h8 c3h6 ratios and a decrease in the h2s ch4 and c6h6 concentrations and in the gas steam ratio a few months after a drastic decrease in seismic activity the so2 hcl and co concentrations and the c2h6 c2h4 and c3h8 c3h6 ratios strongly decreased whereas the ch4 and c6h6 concentrations and the gas steam ratios increased according to the trends shown by both the geochemical parameters and the seismic signals late in the observation period the risk of a rejuvenation of volcanic activity at teide is considered to be low the associated temporal changes in seismic activity and magmatic degassing indicate that geophysical and fluid geochemistry signals in this system are related future monitoring programs aimed at mitigating volcanic hazard on tenerife island should involve coupled geophysical and geochemical studies

radon and helium in soil gases in the phlegraean fields central italy the distribution and migration of radon and soil gas concentrations in the phlegraean fields italy are controlled by the tectonic features of the area radon is supplied from surficial sources and helium has both surficial and deep origins there is no direct correlation between the two noble gases on a point to point basis but the areal distribution of both gases is similar suggesting that the distribution is controlled primarily by fractures and movement of geothermal fluids

diffuse surface emanations as indicator of structural permeability in fault controlled geothermal systems abstract diffuse degassing processes provide valuable information on geothermal reservoir characteristics not only in the context of monitoring but also for exploration purposes areas with increased gas emissions can be indicative of major upflow zones from the reservoir through deep reaching permeable fault zones these fault zones may act as preferential target areas for geothermal production drillings in this study it is successfully demonstrated that diffuse degassing measurements can be used for the detection and characterization of permeable structural elements the combination of following techniques has been applied at the brady s geothermal system in the basin and range province nevada usa accumulation chamber method for carbon dioxide and hydrogen sulfide measurements alpha spectroscopic measurements of radon and thoron activity concentrations and gamma spectroscopic measurements of selected nuclides

extensional collapse of the northern taiwan mountain belt as an active collision zone between the luzon arc and the china continental margin the taiwan mountain belt particularly its south central part is undergoing crustal shortening and rapid uplift the northern part of the orogen is however subjected to crustal stretching and rifting as a result of flipping of subduction from the northwest facing luzon arc system to the south facing ryukyu arc system taiwan and its neighboring southern ryukyu used to be part of the rifted china continental margin before the collision started in late miocene time engineered by the northwest movement of the philippine sea plate in the past 5 m y the north south trending luzon arc obliquely overrode the northeast southwest trending continental margin and tectonized it into a collision orogen that progressively enlarged and migrated from northeast to southwest following the southwest propagating collision the north dipping philippine sea plate which was subducting beneath the ryukyu arc also extended westward and caused flipping of subduction in the northern part of the collision orogen in consequence the orogen lost the compressive support by the colliding plates and became subjected to lithospheric stretching induced by the trench suction the collision orogen collapsed as a result of crustal thinning and its central part foundered into a deep submerged basin a whole spectrum of active tectonic scenarios ranging from orogenic buildup by collision to orogenic collapse by rifting and subsidence can be readily observed in the taiwan ryukyu area and provides a vivid example for the process of orogenic collapse

quantification of carbon dioxide emissions of ciomadul the youngest volcano of the carpathian pannonian region eastern central europe romania abstract we provide the first high resolution co 2 flux data for the neogene to quaternary volcanic regions of the entire carpathian pannonian region eastern central europe and estimate the co 2 emission of the seemingly inactive ciomadul volcanic complex the youngest volcano of this area our estimate includes data from focused and diffuse co 2 emissions from soil the co 2 fluxes of focused emissions range between 277 and 8172 g d 1 corresponding to a co 2 output into the atmosphere between 0 1 and 2 98 t per year the investigated areas for diffuse soil gas emissions were characterized by wide range of co 2 flux values at apor baths ranging from 1 7 10 1 to 8 2 10 4 g m 2 d 1 while at l z re ti ranging between 1 43 and 3 8 10 4 g m 2 d 1 the highest co 2 focused gas fluxes at ciomadul were found at the periphery of the youngest volcanic complex which could be explained either by tectonic control across the brittle older volcanic edifices or by degassing from a deeper crustal zone resulting in co 2 flux at the periphery of the supposed melt bearing magma body beneath ciomadul the estimate of the total co 2 output in the area is 8 70 10 3 t y 1 and it is consistent with other long 10 kyr dormant volcanoes with similar age worldwide such as in italy and usa taking into account the isotopic composition of the gases that indicate deep origin of the co 2 emissions this yields further support that ciomadul may be considered indeed a dormant or pams volcano volcano with potentially active magma storage rather than an inactive one furthermore hazard of co 2 outpourings has to be taken into account and it has to be communicated to the visitors finally we suggest that co 2 output of dormant volcanic systems has to be also accounted in the estimation of the global volcanic co 2 budget

volcano hydrothermal activity detected by precise levelling surveys at the tatun volcano group in northern taiwan during 2006 2013 abstract precise levelling surveys were conducted from 2006 to 2013 on three levelling routes in the tatun volcano group tvg located approximately 15 km northeast of taipei to detect deformation in relation to the volcano hydrothermal activities of the tvg uplift was detected around the most active fumarole tayoukeng fumarole throughout the period 2007 to 2011 the uplift rate throughout the period from march 2009 to march 2011 was reduced in comparison to the rate between 2007 and 2009 following this a dormant state or a small amount of subsidence was detected in the period march 2011 to march 2013 and throughout the period from june 2006 to march 2013 subsidence was centred on an area 0 5 km east of the summit of mt cising the highest peak in the tvg a model of two spherical sources was therefore estimated from the deformation recorded from august 2007 to march 2011 using a genetic algorithm a deflation source was obtained about 0 5 km northeast of mt cising at a depth of 2 km and an inflation source was situated approximately 1 km south of the tayoukeng fumarole at a depth of 0 7 km based on previous seismic and amt studies the estimated sources are interpreted as being hydrothermal reservoirs because almost all the benchmarks around mt cising show subsidence at a constant speed we conclude that the deeper hydrothermal reservoir at a depth of 2 km may have been releasing hydrothermal fluid at a constant rate throughout the period from 2006 to 2013 however it was suggested that in 2011 the shallower hydrothermal reservoir at a depth of 0 7 km changed from an inflation state to a dormant state or small deflation based on temporal vertical changes around tayoukeng fumarole a possible model for the volcano hydrothermal system is therefore proposed it is considered that the hydrothermal fluid may be supplied intermittently from the magma chamber to the deeper hydrothermal reservoir at a depth of 2 km although this type of fluid input event may not have occurred during our research period and that the hydrothermal fluid upwelling between mt cising and tayoukeng fumarole flows transversally into a highly cracked and fluid saturated area that continues to tayoukeng fumarole the existence of a shallower hydrothermal reservoir at a depth of 0 7 km in the highly cracked and fluid saturated area is therefore plausible

spatial radon anomalies on active faults in california abstract radon emanation has been observed to be anomalously high along active faults in many parts of the world we tested this relationship by conducting and repeating soil air radon surveys with a portable radon meter across several faults in california the results confirm the existence of fault associated radon anomalies which show characteristic features that may be related to fault structures but vary in time due to other environmental changes such as rainfall across two creeping faults in san juan bautista and hollister the radon anomalies showed prominent double peaks straddling the fault gouge zone during dry summers but the peak to background ratios diminished after significant rain fall during winter across a locked segment of the san andreas fault near olema the anomaly has a single peak located several meters southwest of the slip zone associated with the 1906 san francisco earthquake across two fault segments that ruptured during the magnitude 7 5 landers earthquake in 1992 anomalously high radon concentration was found in the fractures three weeks after the earthquake we attribute the fault related anomalies to a slow vertical gas flow in or near the fault zones radon generated locally in subsurface soil has a concentration profile that increases three orders of magnitude from the surface to a depth of several meters thus an upward flow that brings up deeper and radon richer soil air to the detection level can cause a significantly higher concentration reading this explanation is consistent with concentrations of carbon dioxide and oxygen measured in soil air samples collected during one of the surveys

a mesoscale vortex couplet observed in the trailing anvil of a multicellular convective complex abstract observations collected during the oklahoma kansas pre storm experiment are used to document the evolution and structure of a mesoscale vortex couplet that developed in the mesoscale convective system that occurred on 16 17 june 1985 the evolution of the circulations was captured by dual doppler radar observations for 1 4 hours this allowed an evaluation of the various terms of the vertical vorticity equation which give insight into the mechanisms that are important in the generation of the circulations the primary mechanism responsible for the formation of the observed vortices was the interaction of the larger scale flow with low level momentum transported to higher levels by multiple convective updrafts as a consequence vertical shear of the horizontal wind was important to initial vorticity production the vorticity generated in this manner was subsequently increased in strength due to middle level convergence when the convection weakened and dissipated the primary source of vorticity w

rear inflow in squall lines with trailing stratiform precipitation abstract the relative airflow and accompanying precipitation structure of squall lines trailed by mesoscale regions of stratiform rain are examined with emphasis on the occurrence of rear inflow i e the intrusion of environmental air into these storms across the trailing precipitation boundary three cases from kansas and oklahoma provide examples of strong rear inflow which crosses the back edge of the stratiform precipitation area at relative speeds exceeding 10 m s 1 the vertical profiles of relative flow at the trailing precipitation boundary of these three systems were remarkably similar with the rear inflow confined to a jet like layer centered at about 550 mb doppler radar data for two of these cases showed that the rear inflow jet occupied a continuous channel extending from middle levels at the back edge of the stratiform region to lower levels of the leading convective region where it merged with outflow from convective downdrafts to bolster the leading gust front strong front to rea

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

diagnosis of hydrometeor profiles from area mean vertical velocity data a simple one dimensional microphysical retrieval model is developed for estimating vertical profiles of liquid and frozen hydrometeor mixing ratios from observed vertical profiles of area mean vertical velocity in regions of convective and or stratiform precipitation the mean vertical velocity profiles can be obtained from doppler radar single and dual or other means the one dimensional results are shown to be in good agreement with two dimensional microphysical fields from a previous study sensitivity tests are performed

three dimensional evolution of simulated long lived squall lines abstract simulations of squall lines using nonhydrostatic convection resolving models have been limited to two dimensions or three dimensions with the assumption of along line periodicity the authors present 3d nonhydrostatic convection resolving simulations produced using an adaptive grid model where the lines are finite in length and the restriction to along line periodicity is removed the base state for the simulations is characterized by weak shallow shear and high convective available potential energy cape an environment in which longlived midlatitude mesoscale convective systems mcss are observed the simulated systems bear strong resemblance to many observed systems suggesting that large scale forcing absent in the horizontally homogeneous environment is not needed to produce many of the distinguishing features of midlatitude mcss in simulations without coriolis forcing the presence of line ends leads to mature symmetric systems characterized by a central region of strong convectio

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

seismicity characteristics of a potentially active quaternary volcano the tatun volcano group northern taiwan the tatun volcano group tvg is located at the northern tip of taiwan near the capital taipei and close to two nuclear power plants because of lack of any activity in historical times it has been classified as an extinct volcano even though more recent studies suggestthattvgmighthavebeenactiveduringthelast20ka inmay2003aseismicmonitoringprojectatthetvgareawasinitiated by deploying eight three component seismic stations some of them equipped with both short period and broadband sensors during the 18 months observation period local seismicity mainly consisted of high frequency earthquakes either occurring as isolated events or as a continuous sequence in the form of spasmodic bursts mixed and low frequency events were also present during the same period eventhoughtheyoccurredonlyrarely arrivaltimesfromeventswithclearp s wavephaseswereinvertedinordertoobtaina minimum 1dvelocity modelwithstation corrections probabilistic nonlinear earthquakelocationswere calculated for allthese events using the newly derived velocity model most high frequency seismicity appeared to be concentrated near the areas of hydrothermal activity forming tight clusters at depths shallower than 4 km relative locations calculated using the double difference method and utilising catalogue and cross correlation differential traveltimes showed insignificant differences when compared to the nonlinear probabilistic locations in general seismicity in the tvg area seems to be primarily driven by circulation of hydrothermal fluids as indicated by the occurrence of spasmodic bursts mixed low frequency events and a b value 1 17 0 1 higher than in any other part of taiwan these observations that are similar to those reported in other dormant quaternary volcanoes indicate that a magma chamber may still exist beneath tvg and that a future eruption or period of unrest should not be considered unlikely

magmatic fluids of tatun volcanic group taiwan abstract two distinctive magmatic fluids were recognized in the tatun volcanic group tvg taiwan one is a relatively reduced fluid represented by the fumarolic gases at hsiao you ken hyk geothermal field another is an oxidized fluid containing high concentrations of hcl represented by the fumarolic gases at da you ken dyk an intermediate gas was recognized at gung tze ping gtp and she hung ping shp the fumarolic gases at hyk and gtp possess the features of so called primary steam generated on mixing of magmatic gas and meteoric groundwater the fumarolic gases at dyk are a simple mixture between magmatic gas and water vapor of meteoric origin the co 2 h 2 o molar ratio of the magmatic component in the fumarolic gases at dyk was estimated to be 0 018 meanwhile it was estimated to be 0 027 for the fumarolic gases at hyk and gtp suggesting the magma beneath dyk is depleted in volatiles relative to the magma beneath hyk and gtp the estimated co 2 h 2 o ratio for the magmatic component is comparable to that of some active volcanoes in japan suggesting the enrichment of volatiles in the magmas beneath tvg

diffuse emission of co2 from miyakejima volcano japan abstract two soil gas surveys were carried out in may and september 1998 at miyakejima volcano in the izu mariana arc japan co 2 flux values for may and september surveys ranged from 0 1 to 18 150 g m 2 day 1 and from 0 1 to 9685 g m 2 day 1 respectively statistical graphical analysis showed three overlapping populations the spatial distribution of these emissions correlated quite closely with the geothermal and geological characteristics of the studied area the structure releasing higher co 2 is the summit cone oyama and surrounding areas where the most obvious geothermal features occur a total output about 100 150 t day 1 is estimated from this area a good correlation was observed between soil co 2 flux and soil temperature at the summit caldera indicating extensive condensation of fumarolic steam within the upper part of miyakejima carbon isotopic analysis of selected samples inside the summit caldera 13 c co 2 0 90 to 5 70 suggests a mixing of carbon derived from marine limestone and magmatic co 2 while a clear biogenic origin 13 c co 2 14 76 to 25 52 is observed for the diffuse degassing of co 2 outside summit caldera

initiation and development of rear inflow within the 28 29 june 1989 north dakota mesoconvective system abstract five dual doppler analyses spanning a period of 1 5 h are used to document the initiation and development of rear inflow within a high plains squall line the squall line developed as part of the 28 29 june 1989 mesoconvective system that passed through the north dakota thunderstorm project observational network this storm was explosively initiated along a preexisting isolated gust front in an environment of much instability and weak upper air flow and moved within dual doppler coverage soon after its initiation the kinematic analyses were performed over a 90 min period as the squall line continued to develop and move to the east northeast the doppler analyses reveal that the rear inflow was initiated near the high reflectivity cores of the squall line within 20 min of the formation of the system with time the rear inflow expanded rearward increased in intensity and descended to near the surface behind the northern section of the squall line in regions where the squall line dissipated

soil co2 emissions at furnas volcano sao miguel island azores archipelago volcano monitoring perspectives geomorphologic studies and land use planning application accepted for publication in journal of geophysical research copyright 2010 american geophysical union

carbon dioxide diffuse emission and thermal energy release from hydrothermal systems at copahue caviahue volcanic complex argentina abstract the north western sector of caviahue caldera argentina close to the active volcanic system of copahue is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions anomalous soil diffuse degassing of co2 and hot soils in march 2014 measurements of soil co2 fluxes in 5 of these sites namely las maquinas las maquinitas i las maquinitas ii anfiteatro and termas de copahue allowed an estimation that 165 t of deeply derived co2 is daily released the gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges gas equilibria within the h c o gas system indicate the presence of a large probably unique single phase vapor zone at 200 210 c feeding the hydrothermal manifestations of las maquinas las maquinitas i and ii and termas de copahue a natural thermal release of 107 mw was computed by using co2 as a tracer of the original vapor phase the magmatic signature of the incondensable fumarolic gases the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the caviahue caldera