co2 emissions related to the yellowstone volcanic system 2 statistical sampling total degassing and transport mechanisms a stratified adaptive sampling plan was designed to estimate co2 degassing in yellowstone national park and was applied in the mud volcano thermal area the stratified component of the sampling design focused effort in thermal areas and the adaptive component in high flux regions yet neither sampling technique biased the estimate of total degassing both diffuse soil fluxes up to 30 000 g m 2d 1 and emission rates from thermal vents up to 1 7 108 mol yr 1 were measured in thermal areas soil fluxes observed in most nonthermal regions were similar to values reported for conifer forests 15 g m 2 d 1 however through adaptive sampling high flux vegetated sites were identified in mud volcano that likely would not have been found if sampling was focused in obvious thermal or altered regions a simple model applied to flux measurements suggests that 40 of the analyzed measurements were dominated by possible advective transport and 30 by diffusive transport isotopic signatures of soil co2 generally suggest a deep origin 13c 2 3 to 0 0 in thermal areas and biogenic origin 13c 20 5 in nonthermal low flux areas vent emissions accounted for 32 63 of the total degassing observed at mud volcano 2 4 to 4 0 109 mol yr 1 the largest source of error in the estimation of total degassing factor of 2 resulted because the population distribution of thermal feature emissions was indeterminate total co2 emissions at mud volcano are comparable to other hydrothermal regions worldwide suggesting that the yellowstone volcanic system is likely a large contributor to global volcanic metamoohic hydrothermal vmh emissions

investigation by multivariate analysis of groundwater composition in a multilayer aquifer system from north africa a multi tracer approach abstract a multi tracer approach has been carried out in the sbeitla multilayer aquifer system central tunisia to investigate the geochemical evolution the origin of groundwaters and their circulation patterns it involves statistical data analysis coupled with the definition of the hydrochemical and isotopic features of the different groundwaters principal components analysis pca of geochemical data used in conjunction with bivariate diagrams of major and trace elements indicate that groundwater mineralization is mainly controlled by water rock interaction and anthropogenic processes in relation to return flow of irrigation waters the pca of isotopic data and bivariate conventional diagrams of stable and radiogenic isotopes i e 18o vs 2h and 18o vs 14c provide valuable information about the origin and the circulation patterns of the different groundwater groups they permit classifying groundwaters into three groups the first group is characterized by low 3h concentrations low 14c activities and depleted stable isotope contents it corresponds to an old end member in relation with palaeoclimatic recharge which occurred during the late pleistocene and the early holocene humid periods the second group is distinguished by high to moderate 3h concentrations high 14c activities and enriched heavy isotope signatures it corresponds to a modern end member originating from a mixture of post nuclear and present day recharge in relation to return flow of irrigation waters the third group is characterized by an average composition of stable and radiogenic isotope signatures it provides evidence for the mixing between the upward moving palaeoclimatic end member and the downward moving present day end member

monitoring gas and heat emissions at norris geyser basin yellowstone national park usa based on a combined eddy covariance and multi gas approach abstract we quantified gas and heat emissions in an acid sulfate vapor dominated area 0 04 km2 of norris geyser basin located just north of the 0 63 ma yellowstone caldera and near an area of anomalous uplift from 14 may to 3 october 2016 an eddy covariance system measured half hourly co2 h2o and sensible h and latent le heat fluxes and a multi gas instrument measured 1 hz frequency atmospheric h2o co2 and h2s volumetric mixing ratios we also measured soil co2 fluxes using the accumulation chamber method and temperature profiles on a grid and collected fumarole gas samples for geochemical analysis eddy covariance co2 fluxes ranged from 56 to 885 g m 2 d 1 using wavelet analysis average daily eddy covariance co2 fluxes were locally correlated with average daily environmental parameters on several day to monthly time scales estimates of co2 emission rate from the study area ranged from 8 6 t d 1 based on eddy covariance measurements to 9 8 t d 1 based on accumulation chamber measurements eddy covariance water vapor fluxes ranged from 1178 to 24 600 g m 2 d 1 nighttime h and le were considered representative of hydrothermal heat fluxes and ranged from 4 to 183 and 38 to 504 w m 2 respectively the total hydrothermal heat emission rate h le radiant estimated for the study area was 11 6 mw and le contributed 69 of the output the mean standard deviation of h2o co2 and h2s mixing ratios measured by the multi gas system were 9 3 3 1 parts per thousand 467 61 ppmv and 0 5 0 6 ppmv respectively and variations in the gas compositions were strongly correlated with diurnal variations in environmental parameters wind speed and direction atmospheric temperature after removing ambient h2o and co2 the observed variations in the multi gas data could be explained by the mixing of relatively h2o co2 h2s rich fumarole gases with co2 rich and h2o h2s poor soil gases the fumarole h2o co2 and co2 h2s end member ratios 101 7 and 27 1 respectively on average were invariant during the measurement period and fell within the range of values measured in direct fumarole gas samples the soil gas h2o co2 end member ratios 15 30 were variable and low relative to the fumarole end member likely resulting from water vapor loss during cooling and condensation in the shallow subsurface whereas the co2 h2s end member ratio was high 160 presumably related to transport of co2 dominated soil gas emissions mixed with trace fumarolic emissions to the multi gas station nighttime eddy covariance ratios of h2o to co2 flux were typically between the soil gas and fumarole end member h2o co2 ratios defined by multi gas measurements overall the combined eddy covariance and multi gas approach provides a powerful tool for quasi continuous measurements of gas and heat emissions for improved volcano hydrothermal monitoring

new gas geothermometers for geothermal exploration calibration and application calibration of five gas geothermometers is presented three of which used co2 h2s and h2 concentrations in fumarole steam respectively the remaining two use co2h2 and h2sh2 ratios the calibration is based on the relation between gas content of drillhole discharges and measured aquifer temperatures after establishing the gas content in the aquifer gas concentrations were calculated in steam formed by adiabatic boiling of this water to atmospheric pressure to obtain the gas geothermometry functions it is shown that the concentrations of co2 h2s and h2 in geothermal reservoir waters are fixed through equilibria with mineral buffers at temperatures above 230 c epidote prehnite calcite quartz are considered to buffer co2 two buffers are involved for h2s and h2 and two functions are therefore presented for the geothermometers involving these gases for waters containing less than about 500 ppm chloride and in the range 230 300 c pyrite pyrrholite epidote prehnite seem to be involved but pyrite epidote prehnite magnetite or chlorite for waters above 300 c and waters in the range 230 300 c if containing over about 500 ppm the gas geothermometers are useful for predicting subsurface temperatures in high temperature geothermal systems they are applicable to systems in basaltic to acidic rocks and in sediments with similar composition but should be used with reservation for systems located in rocks which differ much in composition from the basaltic to acidic ones the geothermometry results may be used to obtain information on steam condensation in upflow zones or phase separation at elevated pressures measured aquifer temperatures in drillholes and gas geothermometry temperatures based on data from nearby fumaroles compare well in the five fields in iceland considered specifically for the present study as well as in several fields in other countries for which data were inspected the results of the gas geothermometers also compare well with the results of solute geothermometers and mixing models in three undrilled icelandic fields

the use of mixing models and chemical geothermometers for estimating underground temperatures in geothermal systems abstract application of various chemical geothermometers and mixing models indicate underground temperatures of 260 c 280 c and 265 c in the geysir hveravellir and landmannalaugar geothermal fields in iceland respectively mixing of the hot water with cold water occurs in the upflow zones of all these geothermal systems linear relations between chloride boron and 18o constitute the main evidence for mixing which is further substantiated by chloride silica and sulphate relations in the geysir and hveravellir fields a new carbonate silica mixing model is proposed which is useful in distinguishing boiled and non boiled geothermal waters this model can also be used to estimate underground temperatures using data from warm springs this model as well as the chloride enthalpy model and the na li and co2 gas geothermometers invariably yield similar results as the quartz geothermometer sometimes also does by contrast the na k and the na k ca geothermometers yield low values in the case of boiling hot springs largely due to loss of potassium from solution in the upflow the results of these geothermometers are unreliable for mixed waters due to leaching subsequent to mixing

comparative soil co2 flux measurements and geostatistical estimation methods on masaya volcano nicaragua we present a comparative study of soil co2 flux f rm co 2 measured by five groups groups 1 5 at the iavcei ccvg eighth workshop on volcanic gases on masaya volcano nicaragua groups 1 5 measured f rm co 2 using the accumulation chamber method at 5 m spacing within a 900 m2 grid during a morning am period these measurements were repeated by groups 1 3 during an afternoon pm period measured f rm co 2 ranged from 218 to 14 719 g m 2 day 1 the variability of the five measurements made at each grid point ranged from 5 to 167 however the arithmetic means of fluxes measured over the entire grid and associated total co2 emission rate estimates varied between groups by only 22 all three groups that made pm measurements reported an 8 19 increase in total emissions over the am results based on a comparison of measurements made during am and pm times we argue that this change is due in large part to natural temporal variability of gas flow rather than to measurement error in order to estimate the mean and associated co2 emission rate of one data set and to map the spatial f rm co 2 distribution we compared six geostatistical methods arithmetic and minimum variance unbiased estimator means of uninterpolated data and arithmetic means of data interpolated by the multiquadric radial basis function ordinary kriging multi gaussian kriging and sequential gaussian simulation methods while the total co2 emission rates estimated using the different techniques only varied by 4 4 the f rm co 2 maps showed important differences we suggest that the sequential gaussian simulation method yields the most realistic representation of the spatial distribution of f rm co 2 but a variety of geostatistical methods are appropriate to estimate the total co2 emission rate from a study area which is a primary goal in volcano monitoring research

groundwater chemistry and water rock interactions at stripa groundwaters from near surface to a depth of 1232 m in the stripa granite have been sampled and analyzed for major and trace constituents the groundwater composition consists of two general types a typical recharge water of ca hco3 type 700 m depth of high ph 8 10 that reaches a maximum of 1250 mg l in total dissolved solids tds intermediate depths show mixtures of the two types that are highly fracture dependent rather than depth dependent any borehole can vary significantly and erratically in tds for either a horizontal or vertical direction the general transition from ca hco3 type to na ca cl type correlates with the depth profile for hydraulic conductivity that drops from 10 8 m s to 10 11 m s or lower thermomechanical stress from heater experiments clearly shows an effect on the groundwater composition that could be caused by changing flow paths leakage of fluid inclusions or both dissolution and precipitation of calcite fluorite and barite aluminosilicate hydrolysis and addition of a saline source possibly fluid inclusion leakage play the major roles in defining the groundwater composition the low permeability of the stripa granite has produced a groundwater composition that appears intermediate between the dilute shallow groundwaters typical of recharge in a crystalline rock terrain and the saline waters and brines typical of cratonic shield areas at depth

bubble collapse as the source of tremor at old faithful geyser old faithful geyser yellowstone was used as a natural laboratory for fluid flow induced seismic activity pressure measurements within the geyser s water column obtained simultaneously with seismic measurements on the surface demonstrated that the tremor observed at old faithful results from impulsive events in the geyser tremor intensity is controlled by the rate of occurrence of these impulsive events there is no resonance observed within the water column the impulsive events are modeled by a collapse of a spherical bubble including the effects of residual non condensible gas and damping the pressure data can be explained by a collapse of a 5 cm radius bubble driven by a pressure difference of p 0 3 10 5 pa and effective viscosity e 0 04 m 2 s using a quasi static geyser model we treat the individual bubble collapses as cooling events that occur when the water column reaches a critical temperature their rate of occurrence is controlled by the heating rate dt dt of the water column as a result the intensity of the hydrothermal and seismic activities is determined by the heat and mass input rate into the geyser it is demonstrated that a sharp widening of the conduit can cause the number of events per unit time to drop as observed while the water level is still rising and heat is being input and thus the tremor intensity can be modulated by variations in the conduit shape

towards understanding the puzzling lack of acid geothermal springs in tibet china insight from a comparison with yellowstone usa and some active volcanic hydrothermal systems abstract explanations for the lack of acid geothermal springs in tibet are inferred from a comprehensive hydrochemical comparison of tibetan geothermal waters with those discharged from yellowstone usa and two active volcanic areas nevado del ruiz colombia and miravalles costa rica where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin for the hydrothermal areas investigated in this study there appears to be a relationship between the depths of magma chambers and the occurrence of acid chloride rich springs formed via direct magmatic fluid absorption nevado del ruiz and miravalles with magma at or very close to the surface less than 1 2 km exhibit very acidic waters containing hcl and h2so4 in contrast the tibetan hydrothermal systems represented by yangbajain usually have fairly deep seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface the absence of steam heated acid waters in tibet however may be primarily due to the lack of a confining layer like young impermeable lavas at yellowstone to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below tibet carry less h2s than those below yellowstone

integrated structural geology and engineering rock mechanics approach to site characterization abstract in line with the symposium theme of linking science to rock engineering this paper presents an integrated structural geology and engineering rock mechanics approach to site characterization structural geology interpretation has much to contribute to the overall understanding of rock mass structure and site characterization for engineering design this applies not only to rock mass geometry rock properties and geological mechanisms but also to the process of modelling and identifying the critical mechanisms for engineering project design the approach is illustrated by three examples relating to rock properties gold mine stability and restoration of 6th century buddhist monolithic cave temples in india

periodic changes in effluent chemistry at cold water geyser crystal geyser in utah crystal geyser is a co2 driven cold water geyser which was originally drilled in the late 1930 s in green river utah utilizing a suite of temporal groundwater sample datasets in situ monitoring of temperature pressure ph and electrical conductivity from multiple field trips to crystal geyser from 2007 to 2014 periodic trends in groundwater chemistry from the geyser effluent were identified based on chemical characteristics the primary sourcing aquifers are characterized to be both the entrada and navajo sandstones with a minor contribution from paradox formation brine the single eruption cycle at crystal geyser lasted over four days and was composed of four parts minor eruption mep major eruption mep aftershock eruption ae and recharge r during the single eruption cycle dissolved ionic species vary 0 44 even though the degree of changes for individual ions are different generally na k cl and so42 regularly decrease at the onset and throughout the mep these species then increase in concentration during the mep conversely ca2 mg2 fe2 and sr2 increase and decrease in concentration during the mep and mep respectively the geochemical inverse modeling with phreeqc was conducted to characterize the contribution from three end members entrada sandstone navajo sandstone and paradox formation brine to the resulting crystal geyser effluent results of the inverse modeling showed that during the mep the navajo entrada and brine supplied 62 65 36 33 and 1 2 respectively during the mep the contribution shifted to 53 56 45 42 and 1 2 for the navajo entrada and paradox formation brine respectively the changes in effluent characteristics further support the hypothesis by watson et al 2014 that the mep and mep are driven by different sources and mechanisms

eruptions at lone star geyser yellowstone national park usa 1 energetics and eruption dynamics 1 geysers provide a natural laboratory to study multiphase eruptive processes we present results from a 4 day experiment at lone star geyser in yellowstone national park usa we simultaneously measured water discharge acoustic emissions infrared intensity and visible and infrared video to quantify the energetics and dynamics of eruptions occurring approximately every 3 h we define four phases in the eruption cycle 1 a 28 3 min phase with liquid and steam fountaining with maximum jet velocities of 16 28 m s 1 steam mass fraction of less than 0 01 intermittently choked flow and flow oscillations with periods increasing from 20 to 40 s are coincident with a decrease in jet velocity and an increase of steam fraction 2 a 26 8 min posteruption relaxation phase with no discharge from the vent infrared ir and acoustic power oscillations gliding between 30 and 40 s 3 a 59 13 min recharge period during which the geyser is quiescent and progressively refills and 4 a 69 14 min preplay period characterized by a series of 5 10 min long pulses of steam small volumes of liquid water discharge and 50

in situ observations of old faithful geyser in a series of experiments from 1983 to 1993 four probes were carefully lowered into old faithful geyser yellowstone national park wyoming at different times these probes variously recorded pressure temperature time conditions to nearly 22 m depth and video probes showed the conduit geometry and processes of recharge to 13 m depth temperatures recorded were within experimental error the same as those recorded in 1942 with a peak bottom temperature t of 118 c processes observed include fog formation in the upper levels of the conduit owing to wind and entrainment of cool air bank storage of hot water that splashes to high levels cools and recharges recharge of cooler ground water into the conduit superheated steam expansion into the conduit t 129 5 c periodic temperature fluctuations and exsolution of bubbles of noncondensable gas which we propose are co 2

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

measuring pressure in the source region for geysers geyser valley kamchatka abstract liquid water and steam that erupt at geysers are provided from deeper reservoirs whose location geometry and pressure are in general poorly known here we report measurements at two geysers from a field experiment in geyser valley kamchatka designed to measure pressure in the reservoir providing water to the geysers water level in the geyser conduit was controlled and the recharge to the geyser conduit was measured by monitoring the discharge needed to maintain the controlled water level recharge is not constant but depends on water level in the geyser from the relationship between water level in the conduit and recharge to the conduit we can estimate the hydraulic head in the reservoir that supplies water to the geyser hydraulic head in the two studied reservoirs is within a couple of meters of the elevation of the geyser vents and the adjacent rivers pressures in the reservoirs are low enough that the reservoirs should not be prone to hydrothermal explosions and explain why flooding of geysers in geyser valley terminated their eruptions

dynamics within geyser conduits and sensitivity to environmental perturbations insights from a periodic geyser in the el tatio geyser field atacama desert chile abstract despite more than 200 years of scientific study the internal dynamics of geyser systems remain poorly characterized as a consequence there remain fundamental questions about what processes initiate and terminate eruptions and where eruptions begin over a one week period in october 2012 we collected down hole measurements of pressure and temperature in the conduit of an exceptionally regular geyser 132 s cycle located in the chilean desert we identified four stages in the geyser cycle 1 recharge of water into the conduit after an eruption driven by the pressure difference between water in the conduit and in a deeper reservoir 2 a pre eruptive stage that follows the recharge and is dominated by addition of steam from below 3 the eruption which occurs by rapid boiling of a large mass of water at the top of the water column and decompression that propagates boiling conditions downward and 4 a relaxation stage during which pressure and temperature decrease until conditions preceding the recharge stage are restored eruptions are triggered by the episodic addition of steam coming from depth suggesting that the dynamics of the eruptions are dominated by geometrical and thermodynamic complexities in the conduit and reservoir further evidence favoring the dominance of internal processes in controlling periodicity is also provided by the absence of responses of the geyser to environmental perturbations air pressure temperature and probably also earth tides

geothermal solute flux monitoring and the source and fate of solutes in the snake river yellowstone national park wy abstract the combined geothermal discharge from over 10 000 features in yellowstone national park ynp can be can be estimated from the cl flux in the madison yellowstone falls and snake rivers over the last 30 years the cl flux in ynp rivers has been calculated using discharge measurements and cl concentrations determined in discrete water samples and it has been determined that approximately 12 of the cl flux exiting ynp is from the snake river the relationship between electrical conductivity and concentrations of cl and other geothermal solutes was quantified at a monitoring site located downstream from the thermal inputs in the snake river beginning in 2012 continuous 15 min electrical conductivity measurements have been made at the monitoring site combining continuous electrical conductivity and discharge data the cl and other geothermal solute fluxes were determined the 2013 2015 cl fluxes 5 3 5 8 kt yr determined using electrical conductivity are comparable to historical data in addition synoptic water samples and discharge data were obtained from sites along the snake river under low flow conditions of september 2014 the synoptic water study extended 17 km upstream from the monitoring site surface inflows were sampled to identify sources and to quantify solute loading the lewis river was the primary source of cl na k cl sio2 rb and as loads 50 80 in the snake river the largest source of so4 was from the upper snake river 50 most of the ca and mg 50 55 originate from the snake hot springs chloride ca mg na k sio2 f hco3 so4 b li rb and as behave conservatively in the snake river and therefore correlate well with conductivity r2 0 97

the origin of harmonic tremor at old faithful geyser volcanic tremor the seismic signal which is often associated with eruptions is among the least understood phenomena in seismology large variations in the physical properties of volcanic rocks and fluids along with the complex geological structure make it difficult to obtain reliable source models old faithful geyser yellowstone national park was chosen as a laboratory for studying fluid flow induced seismicity the geyser s cyclic behavior on an hourly time scale and its accessibility make it suitable for a detailed study of seismic behavior between eruptions simultaneously with underwater pressure measurements inside the geyser we observe that sharp pressure pulses inside the water column attributed to steam bubble collapse are followed by distinct seismic events with a sharp onset and a harmonic horizontal motion whose frequency varies spatially but not temporally a superposition of these events creates the appearance of continuous harmonic tremor since the pressure in the water column exhibits no sign of resonance the harmonic motion must be caused by elastic waves reverberating in the solid medium a near surface soft layer is demonstrated to be a possible elastic model the harmonic tremor observed at old faithful seems analogous to some examples of shallow volcanic tremor

carbon dioxide and hydrogen sulfide degassing and cryptic thermal input to brimstone basin yellowstone national park wyoming abstract brimstone basin a remote area of intense hydrothermal alteration a few km east of the yellowstone caldera is rarely studied and has long been considered to be a cold remnant of an ancient hydrothermal system a field campaign in 2008 confirmed that gas emissions from the few small vents were cold and that soil temperatures in the altered area were at background levels geochemical and isotopic evidence from gas samples 3 he 4 he 3r a 13 c co 2 3 however indicate continuing magmatic gas input to the system accumulation chamber measurements revealed a surprisingly large diffuse flux of co 2 277 t d 1 and h 2 s 0 6 t d 1 the flux of co 2 reduces the 18 o content of the overlying cold groundwater and related stream waters relative to normal meteoric waters simple isotopic modeling reveals that the co 2 likely originates from geothermal water at a temperature of 93 19 c these results and the presence of thermogenic hydrocarbons c1 c2 100 and 13 c ch 4 46 4 to 42 8 in gases require some heat source at depth and refute the assumption that this is a fossil hydrothermal system

heat and mass transport in sublacustrine vents in yellowstone lake wyoming in situ chemical and temperature data documenting a dynamic hydrothermal system abstract recent advances in the development of in situ chemical and temperature sensors have shown great promise as a means to investigate time series changes in marine and terrestrial hydrothermal systems here we apply this technology to assess chemical and physical controls on sublacustrine vent fluids in yellowstone lake wy autonomous sensor systems were deployed in august 2017 using rov assets to position instruments at two sites in the deep hole region of the lake off shore from stevenson island earlier studies have documented that fissure related depressions 120 m water depth in this region host numerous vents issuing high enthalpy co2 saturated and h2s bearing vapor at temperatures in excess of 150 c the ysz ceramic based in situ chemical sensors deployed here were designed to measure ph and redox at 60 s intervals for up to one year two titanium sheathed thermocouples one coupled directly to the electrochemical sensor and another independently powered and positioned slightly deeper in vents at deployment sites provided insight on maximum temperature in the near surface region in addition to in situ chemical and temperature data vent fluid samples were acquired at the outset and during recovery with a novel isobaric system that maintains lake bottom pressure precluding fluid sample de gassing at the same time push cores of vents and in the near vent region were also acquired the mineralized cores provide evidence of long term mass transfer processes while also facilitating insertion and stabilization of the sensor units on the lake floor recovery of the sensors documented similar chemical controls at both sites suggesting compositionally invariant vapor influx characterized by moderately low ph 4 5 and reducing conditions buffered by co2 and h2s respectively accordingly the diatomaceous sediment was extensively altered to kaolinite and pyrite temperature variability at the two sites was especially significant one site site b situated on the slope of what might be a hydrothermal domal structure demonstrated noteworthy cooling and heating episodes that may be associated with hydrothermally or seismically triggered sediment slumping events upon instrument recovery in 2018 the vent site was largely sediment covered and the sensor insert showed evidence of dis location and melting by conductive heating under the hot sediment overburden the initially active and high temperature vent fluid 148 c had largely ceased and replaced by diffuse flow venting at the margin of the previous up flow zone the time series in situ chemical and physical data obtained in the course of the study document the existence of a dynamic hydrothermal system in time and space while underscoring the challenges of research of this type in such environments

investigation of tectonically affected groundwater systems through a multidisciplinary approach abstract this study uses a multidisciplinary approach to obtain a complete picture of the groundwater system of complex mountain aquifers an alpine region the north western area of lake como italy characterized by two regional fault systems the breglia and grona fault systems containing different lithologies was investigated using the multidisciplinary approach described here the use of principal components analysis pca classical geochemical bivariate and trivariate diagrams of major and trace elements and geostructural data including remote sensing permitted the identification of three principal groups of water the first group characterized by an enrichment of ca2 and hco 3 flow in limestone the second group is enriched in hco 3 ca2 and mg2 and circulates through dolomite rocks the third group characterized by a decrease of ca2 and mg2 an increase of na k and a high si electrical conductivity ec ratio flow in the basement rocks nevertheless some peculiarities were evident the matching of pca hydrochemical and geostructural information explains the role played by faults in water circulation in particular the breglia fault permits the rise of deep water from crystalline basement and dolomite similarly the grona fault plays a role on drainage in proximity to the contact between the crystalline basement and the sedimentary cover the springs located near the grona fault rise into the crystalline basement but reflect a dolomite water chemistry the multidisciplinary approach allowed understanding of the groundwater system and identification of fault systems not detectable with a geostructural survey

an experimental study of the role of subsurface plumbing on geothermal discharge in order to better understand the diverse discharge styles and eruption intervals observed at geothermal features we performed three series of laboratory experiments with differing plumbing geometries a single straight conduit that connects a hot water bath flask to a vent funnel can originate geyser like periodic eruptions continuous discharge like a boiling spring and fumarole like steam discharge depending on the conduit length and radius the balance between the heat loss from the conduit walls and the heat supplied from the bottom determines whether and where water can condense which in turn controls discharge style next we connected the conduit to a cold water reservoir through a branch simulating the inflow from an external water source colder water located at a higher place than a branching point can flow into the conduit to stop the boiling in the flask controlling the periodicity of the eruption when an additional branch is connected to a second cold water reservoir the two cold reservoirs can interact our experiments show that branching allows new processes to occur such as recharge of colder water and escape of steam from side channels leading to greater variation in discharge styles and eruption intervals this model is consistent with the fact that eruption duration is not controlled by emptying reservoirs we show how differences in plumbing geometries can explain various discharge styles and eruption intervals observed in el tatio chile and yellowstone usa this article is protected by copyright all rights reserved

temporal variations of geyser water chemistry in the upper geyser basin yellowstone national park usa 1 geysers are rare features that reflect a delicate balance between an abundant supply of water and heat and a unique geometry of fractures and porous rocks between april 2007 and september 2008 we sampled old faithful daisy grand oblong and aurum geysers in yellowstone national park s upper geyser basin and characterized temporal variations in major element chemistry and water isotopes 18o d 3h we compare these temporal variations with temporal trends of geyser eruption intervals gei sio2 concentrations and geothermometry indicate that the geysers are fed by waters ascending from a reservoir with temperatures of 190 to 210 c the studied geysers display small and complex chemical and isotopic seasonal variations and geysers with smaller volume display larger seasonal variations than geysers with larger volumes aurum and oblong geysers contain detectable tritium concentrations suggesting that erupted water contains some modern meteoric water we propose that seasonal gei variations result from varying degrees of evaporation meteoric water recharge water table fluctuations and possible hydraulic interaction with the adjacent firehole river we demonstrate that the concentrations of major dissolved species in old faithful geyser have remained nearly constant since 1884 despite large changes in old faithful s eruption intervals suggesting that no major changes have occurred in the hydrothermal system of the upper geyser basin for 120 years our data set provides a baseline for monitoring future changes in geyser activity that might result from varying climate earthquakes and changes in heat flow from the underlying magmatic system

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

chemical geothermometry and geobarometry in hydrothermal aqueous solutions a theoretical investigation based on a mineral solution equilibrium model abstract the theoretical compositions of an aqueous solution in equilibrium with a mineral assemblage made up of low albite k feldspar either a ca al silicate or calcite clinochlore muscovite quartz anhydrite and fluorite under varying t pco2 mcl conditions of geothermal interest indicate that 1 1 the total so4 content as well as the na k k 2 mg and so 4 f 2 ratios are potential geothermometers 2 2 the total hco3 content as well as the k 2 ca ca mg hco 3 f and hco 3 2 so 4 ratios are potential pco2 indicators 3 3 the na k ca and mg total contents as well as the na 2 mg and na 2 ca ratios are mainly controlled by the total ionic salinity and are therefore hardly suitable as geoindicators a preliminary test of the equations involving total hco3 content as well as k 2 ca and hco 3 f ratios as pco2 indicators have provided satisfactory results

multireaction equilibrium geothermometry a sensitivity analysis using data from the lower geyser basin yellowstone national park usa abstract a multireaction chemical equilibria geothermometry meg model applicable to high temperature geothermal systems has been developed over the past three decades given sufficient data this model provides more constraint on calculated reservoir temperatures than classical chemical geothermometers that are based on either the concentration of silica sio2 or the ratios of cation concentrations a set of 23 chemical analyses from ojo caliente spring and 22 analyses from other thermal features in the lower geyser basin of yellowstone national park are used to examine the sensitivity of calculated reservoir temperatures using the geot meg code spycher et al 2013 2014 to quantify the effects of solute concentrations degassing and mineral assemblages on calculated reservoir temperatures results of our analysis demonstrate that the meg model can resolve reservoir temperatures within approximately 15 c and that natural variation in fluid compositions represents a greater source of variance in calculated reservoir temperatures than variations caused by analytical uncertainty assuming 5 for major elements the analysis also suggests that meg calculations are particularly sensitive to variations in silica concentration the concentrations of the redox species fe ii and h2s and that the parameters defining steam separation and co2 degassing from the liquid may be adequately determined by numerical optimization results from this study can provide guidance for future applications of meg models and thus provide more reliable information on geothermal energy resources during exploration

modeling and observations of geyser activity in relation to catastrophic landslides mudflows kronotsky nature reserve kamchatka russia abstract this study reports and interprets observational data of geyser cycling in the valley of geysers and uzon hydrothermal systems between 2007 and 2015 the monitoring of the velikan and bolshoy geysers after the catastrophic landslide on 3 06 2007 which dammed and created podprudnoe lake drowning some geysers and before a mudflow on 3 01 2014 which destroyed the dam and almost completely drained podprudnoe lake shows that the interval between eruptions ibe of the bolshoy geyser decreased from 108 to 63 min and that the ibe of the velikan geyser slowly declined over three years from 379 min to 335 min the seasonal hydrological cycle of the velikan geyser shows an increase in the ibe during winter average of 41 min the dilution of the chloride deep components of the bolshoy 23 and velikan geysers 12 is also observed a local tough2 model of the velikan geyser is developed this model is used to describe the transient thermal hydrodynamic and co 2 changes in a velikan geyser conduit during the entire cycling process by using cyclic time dependent boundary mass flow conditions major eruption discharge and sub cyclically assigned co 2 mass flow recharge into the base of the geyser conduit and water recharge at the mid height of the geyser conduit and a constant mass flow of water into the geyser at depth this model also indicates a seepage element at the conduit s top to allow pre eruptive discharge and a buffering isothermal reservoir below to compensate for pressure declines from major eruptions at earlier times a local tough2 model is successfully calibrated against temperature observations at both the mid height and base of the conduit of the velikan geyser which shows the essential role of the above parameters in describing the functionality of the geyser a reservoir model of shallow production geysers is also developed this 2d model is used to describe changes in the thermal hydrodynamic state and evolving chloride concentrations in the areas of most prominent discharge both at steady state and when perturbed by cold water injection from podprudnoe lake and other cold water sources after 3 06 2007 a well on deliverability option is used to model the geyser discharge features in the model the modeled increases in geyser discharge that is caused by an increase in the reservoir pressure from cold water injection reasonably matches observations of ibe decreases in the bolshoy 58 and velikan geysers 9 the modeling also shows the possibility of chloride dilution in the velikan geyser but no dilution in the bolshoy geyser the latter observation is attributed to the presence of direct cold water inflow into the bolshoy geyser conduit

dating silica sinter geyserite a cautionary tale abstract we describe a new effort to date hydrothermal silica sinter deposits geyserite from the upper geyser basin of yellowstone national park using 14c of co deposited organic matter u series and cosmogenic 10be methods a majority of the samples were collected from stratigraphic sections mainly at riverside giant and castle geysers ages obtained from 41 14c analyses range from modern to 12 1 cal ka bp nearly all the 14c ages show inconsistencies with their stratigraphic positions and several replicate 14c analyses from the same sample result in significantly different ages the 13c values of the organic material in the sinter range from 26 6 to 12 7 the more enriched values are attributed to microbial fixation of dissolved inorganic carbon dic which has heavier 13c values and is 14c depleted relative to atmospheric co2 leading to an apparent older age u series analyses on 4 samples yielded ages between 2 2 and 7 4 ka large 230th u age uncertainties in the sinter due to low uranium concentrations along with elevated 232th and associated initial 230th make these ages imprecise for use on holocene deposits a single cosmogenic 10be exposure age of 596 18 ka is considerably older than the age of underlying rhyolite and is thus unreliable this apparent old age results from contamination by meteoric 10be trapped in the opal that overprints the very small amount of cosmogenic 10be by presenting the problems we encountered and discussing their probable cause this paper highlights the difficulty in obtaining reliable high precision geochronological data necessary to use sinter deposits as paleoenvironmental and paleo hydrothermal archives

relationship between spring and geyser activity and the deposition and morphology of high temperature 73 c siliceous sinter yellowstone national park wyoming u s a abstract six classes of alkaline hot springs and geysers are here distinguished in yellowstone national park based on activity and eruptive style 1 non surging non boiling springs 2 gently surging non boiling springs 3 non surging to gently surging boiling springs 4 strongly surging springs 5 fountain geysers and 6 cone geysers each displays morphologically distinctive siliceous sinter deposits in the high temperature 73 c parts of the vent and outflow systems non surging and gently surging non boiling springs that do not overflow their rims develop thin digitate to lilypad like sinter rims that grow horizontally over the pool surfaces similar springs with rim overflow have rims that accrete vertically boiling springs often have nearly circular steep sided pools and rims dominated by splash and rim overflow and composed mainly of spicular and columnar sinter fountain geysers characterized by broad fountain like eruption bursts have a central vent surrounded by a zone of spicular sinter beyond which is a broad flat bottomed moat but lack steep sinter cones cone geysers have narrow vents jet like discharges that cool rapidly and fall close to the vent and steep sided spicule dominated sinter cones sinter deposition takes place within three main zones 1 fully subaqueous sides and bottoms of vent pools outflow basins and outflow channels 2 periodically wetted splash zones surrounding hot springs and geysers and 3 largely subaerial parts of the rim and outflow areas wetted mainly by overflow and surging and that dry quickly fully subaqueous surfaces are covered by fine earthy particulate siliceous sediment pss composed largely of amorphous silica spherules and spherule aggregates that appear to have precipitated around heterogeneous nuclei including microbes splash zones of hot springs and geysers are characterized by spicular sinter largely subaerial zones wetted mainly by rim overflow and surging with little or no splash show complex varieties of terraced columnar and knobby sinter the highest silica deposition rates occur where surfaces are wetted frequently and evaporate to dryness such as the tops of spicules columns and knobs associated lower areas and crevices that remain wet or moist show slow accumulation of pss most continuously wet surfaces in high temperature 73 c hot spring and geyser vent and outflow systems are probably covered by microbial biofilms although microbes may locally influence rates of silica deposition and sinter microstructure the results of this study suggest that the depositional sites morphology and macrostructuring of high temperature sinter are controlled largely by the processes of surface wetting evaporation and drying

geochemistry and geochronology of the banxi sb deposit implications for fluid origin and the evolution of sb mineralization in central western hunan south china abstract central western hunan in south china hosts the largest antimony belt in the world with two types of sb deposits identified sb au woxi type and sb only xikuangshan type banxi is the most representative deposit in the region with vein type sb mineralization hosted in neoproterozoic clastic rocks stibnite developing in ores and arsenopyrite mainly occurring in altered country rocks trace element contents including rare earth elements ree and isotopic ratios s pb sr nd he and ar in stibnite and or arsenopyrite were analyzed to determine the timing of ore formation and to elucidate fluid origin and evolution processes most sulfides have high ree contents 45 103 ppm moderate fractionation between lree and hree lree hree 6 38 11 56 and slightly negative eu anomalies eu eu 0 53 0 72 the 34 s values are 3 88 5 81 for stibnite and 9 25 11 82 for arsenopyrite the 206 pb 204 pb 207 pb 204 pb and 208 pb 204 pb ratios range from 18 617 to 18 635 15 695 to 15 739 and 38 965 to 38 981 for stibnite and from 18 594 to 18 609 from 15 587 to 15 698 and from 38 893 to 38 926 for arsenopyrite the 87 rb 86 sr and 87 sr 86 sr ratios are 0 3016 3 538 and 0 711463 0 717591 respectively for stibnite and 0 2251 2 214 and 0 711244 0 711565 respectively for arsenopyrite the 147 sm 144 nd and 143 nd 144 nd ratios are 0 1174 0 9816 and 0 511942 0 512768 for stibnite with end t values t 130 ma ranging from 12 4 to 6 6 and two stage model ages t 2dm ranging from 1457 to 1932 ma the 40 ar 36 ar and r ra ratios where ra is the atmospheric 3 he 4 he ratio of 1 4 10 6 are 409 545 and 0 0088 0 0348 respectively for stibnite the rb sr and sm nd isotopic analyses of the sulfides yield isochron ages of 129 4 2 4 ma 2 mswd 1 3 and 130 4 1 9 ma 2 mswd 1 6 respectively the combined trace element and isotopic data set indicates that the ore forming fluids were a mixture of dominantly deep basement derived solute rich parent water and a small amount of dilute heated meteoric water the decreases in ree 34 s 206 pb 204 pb 207 pb 204 pb 208 pb 204 pb 87 rb 86 sr 87 sr 86 sr 147 sm 144 nd and 143 nd 144 nd and increases in 40 ar 36 ar and 4 he contents in the stibnite from the earlier quartz stibnite mineralization stage stage ii through to the later stibnite mineralization stage stage iii indicate that the influx of meteoric water increased during sb mineralization the deep sourced relatively high temperature rock reacted fluid mixed with increasing amounts of more oxidized low temperature meteoric fluids causing the precipitation of arsenopyrite and stibnite sequentially at the banxi deposit a two period genetic model has been proposed for the world class sb mineralization in the central western hunan region the woxi type sb au deposits were derived from orogenic fluids generated from folding and shearing during the caledonian and indosinian orogeny whereas the xikuangshan type sb deposits were formed by mixing heated basement derived hydrothermal fluid circulating during the flare up of magmatism in south china with lower temperature meteoric water

can co2 trigger a thermal geyser eruption geyser eruptions are produced by a complex and poorly understood set of subsurface processes and conditions they typically have an abundant supply of water relatively permeable and competent subsurface material a conduit to the surface a driving mechanism commonly believed to be the initiation of gas lift pumping by steam formation in the conduit and a trigger here we present time series of dissolved co 2 concentrations in near surface discharge waters of a thermal geyser in yellowstone national park northwestern united states that vary systematically over several eruption cycles chemical geothermometry combined with a temperature profile in a nearby well suggests that the geyser water ascends from non boiling conditions 153 171 c at a depth of 57 65 m when the time series of near surface measured co 2 concentrations are extrapolated to these subsurface conditions assuming dominantly adiabatic cooling the additional gas pressure from dissolved co 2 is large enough to cause the total dissolved gas pressure to exceed bubbling pressure inducing bubble formation we postulate that co 2 is a necessary component to triggering eruptions in the geyser studied furthermore unlike steam co 2 bubbles do not completely re condense during cooling in the geyser conduit hence providing better sustenance for gas lift pumping than pure h 2 o boiling

generation and evolution of hydrothermal fluids at yellowstone insights from the heart lake geyser basin 1 we sampled fumaroles and hot springs from the heart lake geyser basin hlgb measured water and gas discharge and estimated heat and mass flux from this geothermal area in 2009 the combined data set reveals that diverse fluids share an origin by mixing of deep solute rich parent water with dilute heated meteoric water accompanied by subsequent boiling a variety of chemical and isotopic geothermometers are consistent with a parent water that equilibrates with rocks at 205 c 10 c and then undergoes 21 2 adiabatic boiling measured diffuse co2 flux and fumarole compositions are consistent with an initial dissolved co2 concentration of 21 7 mmol upon arrival at the caldera boundary and prior to southeast flow boiling and discharge along the witch creek drainage the calculated advective flow from the basin is 78 16 l s 1of parent thermal water corresponding to 68 14 mw or 1 of the estimated thermal flux from yellowstone helium and carbon isotopes reveal minor addition of locally derived crustal biogenic and meteoric gases as this fluid boils and degasses reducing the he isotope ratio rc ra from 2 91 to 1 09 the hlgb is one of the few thermal areas at yellowstone that approaches a closed system where a series of progressively boiled waters can be sampled along with related steam and noncondensable gas at other yellowstone locations steam and gas are found without associated neutral cl waters e g hot spring basin or cl rich waters emerge without significant associated steam and gas upper geyser basin

a conceptual geochemical model of the geothermal system at surprise valley ca abstract characterizing the geothermal system at surprise valley sv northeastern california is important for determining the sustainability of the energy resource and mitigating hazards associated with hydrothermal eruptions that last occurred in 1951 previous geochemical studies of the area attempted to reconcile different hot spring compositions on the western and eastern sides of the valley using scenarios of dilution equilibration at low temperatures surface evaporation and differences in rock type along flow paths these models were primarily supported using classical geothermometry methods and generally assumed that fluids in the lake city mud volcano area on the western side of the valley best reflect the composition of a deep geothermal fluid in this contribution we address controls on hot spring compositions using a different suite of geochemical tools including optimized multicomponent geochemistry geot models hot spring fluid major and trace element measurements mineralogical observations and stable isotope measurements of hot spring fluids and precipitated carbonates we synthesize the results into a conceptual geochemical model of the surprise valley geothermal system and show that high temperature quartz na k na k ca classical geothermometers fail to predict maximum subsurface temperatures because fluids re equilibrated at progressively lower temperatures during outflow including in the lake city area we propose a model where hot spring fluids originate as a mixture between a deep thermal brine and modern meteoric fluids with a seasonally variable mixing ratio the deep brine has deuterium values at least 3 to 4 lighter than any known groundwater or high elevation snow previously measured in and adjacent to sv suggesting it was recharged during the pleistocene when meteoric fluids had lower deuterium values the deuterium values and compositional characteristics of the deep brine have only been identified in thermal springs and groundwater samples collected in proximity to structures that transmit thermal fluids suggesting the brine may be thermal in nature on the western side of the valley at the lake city mud volcano the deep brine meteoric water mixture subsequently boils in the shallow subsurface precipitates calcite and re equilibrates at about 130 c on the eastern side of the valley meteoric fluid mixes to a greater extent with the deep brine cools conductively without boiling and the composition is modified as dissolved elements are sequestered by secondary minerals that form along the cooling and outflow path at temperatures

radiocarbon dating of silica sinter deposits in shallow drill cores from the upper geyser basin yellowstone national park abstract to explore the timing of hydrothermal activity at the upper geyser basin ugb in yellowstone national park we obtained seven new accelerator mass spectrometry ams radiocarbon 14 c ages of carbonaceous material trapped within siliceous sinter five samples came from depths of 15 152 cm within the y 1 well and two samples were from well y 7 depths of 24 cm and 122 cm these two wells at black sand and biscuit basins respectively were drilled in 1967 as part of a scientific drilling program by the u s geological survey white et al 1975 even with samples as small as 15 g we obtained sufficient carbonaceous material a mixture of thermophilic mats pollen and charcoal for the 14 c analyses apparent time of deposition ranged from 3775 25 and 2910 30 14 c years bp at the top of the cores to about 8000 years bp at the bottom the dates are consistent with variable rates of sinter formation at individual sites within the ugb over the holocene on a basin wide scale though these and other existing 14 c dates hint that hydrothermal activity at the ugb may have been continuous throughout the holocene

eruption dynamics of co2 driven cold water geysers crystal tenmile geysers in utah and chimayo geyser in new mexico abstract the co 2 bubble volume fraction eruption velocity flash depth and mass emission of co 2 were determined from multiple wellbore co 2 driven cold water geysers crystal and tenmile geysers in utah and chimayo geyser in new mexico at shallow depths the bubble volume fraction ranges from 0 to 0 8 eruption velocities range from 2 to 20 m s and flash depths are predominately shallow ranging from 5 to 40 m below the surface annual emission of co 2 is estimated to be 4 77 1 92 10 3 6 17 1 73 10 1 6 54 0 57 10 1 t yr for crystal tenmile and chimayo geysers respectively these estimates are coherent with burnside et al 2013 showing that the rate of co 2 leakage from wellbores is greater than fault parallel or diffuse co 2 leakage the geyser plumbing geometry consists of a vertical wellbore which allows for the upward migration of co 2 rich fluids due to artesian conditions the positive feedback system of a co 2 driven eruption occurs within the well active inflow of co 2 into the regional aquifers through faulted bedrock allows geysering to persist for decades crystal geyser erupts for over 24 h at a time highlighting the potential for a wellbore in a natural environment to reach relatively steady state high velocity discharge mitigating high velocity co 2 driven discharge from wellbores will however be easier than mitigating diffuse leakage from faults or into groundwater systems

boiling and dilution in the shallow portion of the waiotapu geothermal system new zealand abstract the waiotapu geothermal system is the largest in terms of surface extent and heat flow 17 km2 and 600 mw respectively of the 20 major geothermal systems in the taupo volcanic zone new zealand two extinct dacite cones and a rhyolite dome rise about 500 m above the waiotapu valley the majority of thermal features occurs in the valley over a relief of only 100 m and lies within coincident apparent resistivity and 30 m depth thermal anomalies thermal features comprise near neutral ph chloride springs often boiling acid sulfate springs and mud pools and mixed waters the latter including both bicarbonate chloride and acid sulfate chloride springs the majority of the sulfate discharges to the surface in the northern higher altitude area while most chloride that reaches the surface does so in the southern portion of the system comparison of measured and calculated surface chloride flux the latter from measured heat flow and reservoir chloride concentrations indicates that at least half of the deep chloride does not discharge at the surface but flows laterally to the south at shallow depths mixing with groundwater the composition of well discharges indicates a shallow 400 m reservoir of chloride fluid about 1350 mg cl kg at 230 c is diluted by a co2 rich steam heated water nil chloride at about 160 c the latter located on the margins of the system this same dilution trend is apparent from the compositional variation and k na and k mg geothermometry of hot spring waters however there is chemical and stable isotope evidence from hot springs that cold groundwater also acts as a diluent at shallow levels and very near the surface steam heated acid sulfate waters mix with the upflow boiling of the deep chloride fluids prior to dilution results in the stabilization of k feldspar in contrast dilution at shallower depths by the steam heated waters both co2 rich and acid sulfate leads to the water compositions initially shifting to k mica and interstratified clay stability and to kaolinite stability with further dilution and temperature decrease the composition and distribution of these fluids are consistent with alteration mineralogy and zonation observed in drill core although boiling occurs at deeper levels and up to the surface in the upflow zone at waiotapu mixing is also common and is the dominant process on the margin and in the near surface portion of the system boiling of deep chloride fluid is very common in the upper 1 2 km of the upflow zone of most geothermal systems though it may be quenched by mixing with marginal waters either cold groundwater in high relief terrane or steam heated waters in areas of lower relief co2 rich steam heated waters are common on the margins of systems and will generally underlie the near surface acid sulfate steam heated waters interaction with co2 rich waters will form k mica and interstratified clays while acid sulfate waters cause kaolinite and even alunite to form the former assemblage is commonly associated with typical low sulfidation epithermal gold mineralization as wallrock alteration where gold bearing veins comprise adularia and illite in contrast kaolinite is rare and alunite absent from a direct spatial and genetic association with gold mineralization in this environment this implies that mixing of the deep neutral ph chloride fluid with surficial acid sulfate waters does not commonly lead to ore grade gold deposition mixing with and cooling by co2 rich steam heated waters leads to clay stability accounting for the large halos of clay alteration and low grade metal anomalies which often surround veins of high gold grade in contrast mixing with surficial acid sulfate waters is unlikely to cause precious metal mineralization because the chloride fluids have already lost the majority of their gold through deeper boiling and dilution

flux of volatiles and ore forming metals from the magmatic hydrothermal system of satsuma iwojima volcano the satsuma iwojima volcano southwest japan degasses 5 x 10 6 t yr h 2 o 9 x 10 4 t yr s and 6 x 10 4 t yr cl from high temperature 880 c fumaroles atop a now altered rhyolite dome that erupted 1200 yr ago acidic hot springs ph 1 1 1 8 discharge 20 x 10 6 t yr h 2 o to the sea this water is composed of 1 part magmatic vapor absorbed by 6 parts meteoric ground water the cl and so 4 in solution originate from the vapor whereas cation components are derived largely by dissolution of the rhyolite the flux of pb zn cu and mo in the vapor and acidic springs ranges from 0 1 to 10 t yr each whereas the au flux is 10 5 and 10 3 t yr respectively the low concentrations of nacl and metals in the vapor are due to the condensation of a hypersaline liquid from the vapor during ascent and depressurization meaning that the atmospheric pressure vapor does not reflect the composition of the fluid exsolving from the magma neither this low pressure vapor nor the acidic waters can account for high sulfidation cu au ore deposits deduced to have formed in this environment such mineralization requires the subsequent ascent of a metal rich fluid

dissolved gases in hydrothermal phreatic and geyser eruptions at yellowstone national park usa multiphase and multicomponent fluid flow in the shallow continental crust plays a significant role in a variety of processes over a broad range of temperatures and pressures the presence of dissolved gases in aqueous fluids reduces the liquid stability field toward lower temperatures and enhances the explosivity potential with respect to pure water therefore in areas where magma is actively degassing into a hydrothermal system gas rich aqueous fluids can exert a major control on geothermal energy production can be propellants in hazardous hydrothermal phreatic eruptions and can modulate the dynamics of geyser eruptions we collected pressurized samples of thermal water that preserved dissolved gases in conjunction with precise temperature measurements with depth in research well y 7 maximum depth of 70 1 m casing to 31 m and five thermal pools maximum depth of 11 3 m in the upper geyser basin of yellowstone national park usa based on the dissolved gas concentrations we demonstrate that co 2 mainly derived from magma and n 2 from air saturated meteoric water reduce the near surface saturation temperature consistent with some previous observations in geyser conduits thermodynamic calculations suggest that the dissolved co 2 and n 2 modulate the dynamics of geyser eruptions and are likely triggers of hydrothermal eruptions when recharged into shallow reservoirs at high concentrations therefore monitoring changes in gas emission rate and composition in areas with neutral and alkaline chlorine thermal features could provide important information on the natural resources geysers and hazards eruptions in these areas

investigation of groundwater chemistry at a dam site during its construction a case study of xiangjiaba dam china water quality can be used to reflect the hydro geological features and seepage restrictions around grout curtains xiangjiaba dam a large hydropower station constructed in southwest of china was investigated as a case study groundwater samples were collected and analysed qualitatively using hydrochemistry diagrams after which the presence of four major water groups was determined by hierarchical cluster analysis and saturation indices of each group were calculated finally inverse geochemical models of the groups were developed using phreeqc to elucidate the dissolution precipitation quality of different minerals and the relative contributions of different seepage sources the hydro geochemical methods used were found to be useful for revealing seepage behaviour within the domain during construction of a hydropower station

coupled variations in helium isotopes and fluid chemistry shoshone geyser basin yellowstone national park abstract early studies of 3he 4he variations in geothermal systems have generally attributed these fluctuations to either differences in the source of the magmatic 3he rich helium or to local differences in the deep flux of magmatic 3he rich helium kennedy et al 1987 however show that near surface processes such as boiling and dilution may also drastically affect 3 he 4 he ratios of geothermal vapors helium isotope ratios were determined for several hot springs at shoshone geyser basin of yellowstone national park for this study along with other noble gas data stable isotope data and water and gas chemistry data for each spring were also compiled the water chemistry indicates that there is one deep hot thermal water in the area which is mixing with dilute meteoric water that has entered the system at depth spring hco3 concentrations correlate with 3 he 4 he values as in nearby lower geyser basin this correlation is attributed to variable amounts of deep dilution of thermal waters with a relatively cool water that inhibits boiling at depth thus preventing the loss of co2 and therefore hco3 and magmatic he in the most diluted samples oxygen and hydrogen isotope data also support a boiling and dilution model but to produce the observed fractionations the boiling event would have to be extensive with steam loss at the surface whereas the boiling that affected the helium isotope ratios was probably a small scale event with steam loss at depth it is possible that deep boiling occurred in the basin and that small amounts of steam escaped along fractures at about 500 m below the surface while all subsequently produced steam was lost near or at the surface

using multivariate statistical analysis of groundwater major cation and trace element concentrations to evaluate groundwater flow in a regional aquifer groundwater samples were collected from 11 springs in ash meadows national wildlife refuge in southern nevada and seven springs from death valley national park in eastern california concentrations of the major cations ca mg na and k and 45 trace elements were determined in these groundwater samples the resultant data were subjected to evaluation via the multivariate statistical technique principal components analysis pca to investigate the chemical relationships between the ash meadows and death valley spring waters to evaluate whether the results of the pca support those of previous hydrogeological and isotopic studies and to determine if pca can be used to help delineate potential groundwater flow patterns based on the chemical compositions of groundwaters the results of the pca indicated that groundwaters from the regional paleozoic carbonate aquifers all of the ash meadows springs and four springs from the furnace creek region of death valley exhibited strong statistical associations whereas other death valley groundwaters were chemically different the results of the pca support earlier studies where potentiometric head levels 18o and d geological relationships and rare earth element data were used to evaluate groundwater flow which suggest groundwater flows from ash meadows to the furnace creek springs in death valley the pca suggests that furnace creek groundwaters are moderately concentrated ash meadows groundwater reflecting longer aquifer residence times for the furnace creek groundwaters moreover pca indicates that groundwater may flow from springs in the region surrounding scotty s castle in death valley national park to a spring discharging on the valley floor the study indicates that pca may provide rapid and relatively cost effective methods to assess possible groundwater flow regimes in systems that have not been previously investigated copyright 1999 john wiley sons ltd

evolution of geothermal fluids deduced from chemistry plots yellowstone national park u s a mazor e and thompson j m 1982 evolution of geothermal fluids deduced from chemistry plots yellowstone national park u s a j volcanol geotherm res 12 351 360 large amounts of chemical data obtained in geothermal fields may readily be sorted out by the aid of a simple set of graphs that provide a clear over all picture and facilitate the understanding of geochemical processes taking place as a case study data from several hundred samples of the thermal springs at the well known yellow stone national park are discussed the pattern obtained seems to indicate 1 geochemical similarity between the spring groups of heart lake shoshone upper midway lower and norris geyser basins i e a geochemical uniformity of major spring groups located over 40 km apart 2 these groups may be described as originating from a common fluid most resembling the composition of norris waters accompanied by co and other volatiles that react with igneous rocks forming local variations 3 the secondary reactions occur at medium depth before the ascent to the surface 4 extensive concentration dilution processes occur during the ascent to the surface the water of the mammoth group may be described as originating from the same norris like fluid that has been diluted low na and ci contents and intensively reacted with carbonaceous rocks thus gaining in ca mg so and hco

the fascinating and complex dynamics of geyser eruptions geysers episodically erupt liquid and vapor despite two centuries of scientific study basic questions persist why do geysers exist what determines eruption intervals durations and heights what initiates eruptions through monitoring eruption intervals analyzing geophysical data taking measurements within geyser conduits performing numerical simulations and constructing laboratory models some of these questions have been addressed geysers are uncommon because they require a combination of abundant water recharge magmatism and rhyolite flows to supply heat and silica and large fractures and cavities overlain by low permeability materials to trap rising multiphase and multicomponent fluids eruptions are driven by the conversion of thermal to kinetic energy during decompression larger and deeper cavities permit larger eruptions and promote regularity by isolating water from weather variations the ejection velocity may be limited by the speed of sound of the liquid vapor mixture

methane sources and production in the northern cascadia margin gas hydrate system abstract the oceanographic and tectonic conditions of accretionary margins are well suited for several potential processes governing methane generation storage and release to identify the relevant methane evolution pathways in the northern cascadia accretionary margin a four site transect was drilled during integrated ocean drilling program expedition 311 the 13c values of methane range from a minimum value of 82 2 on an uplifted ridge of accreted sediment near the deformation front site u1326 1829 mbsl meters below sea level to a maximum value of 39 5 at the most landward location within an area of steep canyons near the shelf edge site u1329 946 mbsl an interpretation based solely on methane isotope values might conclude the 13c enrichment of methane indicates a transition from microbially to thermogenically sourced methane however the co existing co2 exhibits a similar trend of 13c enrichment along the transect with values ranging from 22 5 to 25 7 the magnitude of the carbon isotope separation between methane and co2 ec 63 8 5 8 is consistent with isotope fractionation during microbially mediated carbonate reduction these results in conjunction with a transect wide gaseous hydrocarbon content composed of 99 8 by volume methane and uniform dch4 values 172 8 that are distinct from thermogenic methane at a seep located 60 km from the expedition 311 transect suggest microbial co2 reduction is the predominant methane source at all investigated sites the magnitude of the intra site downhole 13c enrichment of co2 within the accreted ridge site u1326 and a slope basin nearest the deformation front site u1325 2195 mbsl is 5 at the mid slope site site u1327 1304 mbsl the downhole 13c enrichment of the co2 is 25 and increases to 40 at the near shelf edge site u1329 this isotope fractionation pattern is indicative of more extensive diagenetic alteration at sites with greater 13c enrichment the magnitude of the 13c enrichment of co2 correlates with decreasing sedimentation rates and a diminishing occurrence of stratigraphic gas hydrate we suggest the decreasing sedimentation rates increase the exposure time of sedimentary organic matter to aerobic and anaerobic degradation during burial thereby reducing the availability of metabolizable organic matter available for methane production this process is reflected in the occurrence and distribution of gas hydrate within the northern cascadia margin accretionary prism our observations are relevant for evaluating methane production and the occurrence of stratigraphic gas hydrate within other convergent margins

ground penetrating radar documents short term near surface hydrological changes around old faithful geyser yellowstone national park usa abstract in april 2015 ground penetrating radar gpr was used to characterize the shallow subsurface

spatial and temporal geochemical trends in the hydrothermal system of yellowstone national park inferences from river solute fluxes we present and analyze a chemical dataset that includes the concentrations and fluxes of hco3 s o4 c l and f in the major rivers draining yellowstone national park ynp for the 2002 2004 water years 1 october 2001 30 september 2004 the total molar flux in all rivers decreases in the following order hco3 ncl nso4 nf but each river is characterized by a distinct chemical composition implying large scale spatial heterogeneity in the inputs of the various solutes the data also display nonuniform temporal trends whereas solute concentrations and fluxes are nearly constant during base flow conditions concentrations decrease solute fluxes increase and hco3 cl and so4 cl increase during the late spring high flow period hco3 so4 decreases with increasing discharge in the madison and falls rivers but increases with discharge in the yellowstone and snake rivers the non linear relations between solute concentrations and river discharge and the change in anion ratios associated with spring runoff are explained by mixing between two components 1 a component that is discharged during base flow conditions and 2 a component associated with snow melt runoff characterized by higher hco3 cl and so4 cl the fraction of the second component is greater in the yellowstone and snake rivers which host lakes in their drainage basins and where a large fraction of the solute flux follows thaw of ice cover in the spring months although the total river hco3 flux is larger than the flux of other solutes hco3 cl 3 the co2 equivalent flux is only 1 of the estimated emission of magmatic co2 soil emissions from yellowstone no anomalous solute flux in response to perturbations in the hydrothermal system was observed possibly because gage locations are too distant from areas of disturbance or because of the relatively low sampling frequency in order to detect changes in river hydrothermal solute fluxes sampling at higher frequencies with better spatial coverage would be required our analysis also suggests that it might be more feasible to detect large scale heating or cooling of the hydrothermal system by tracking changes in gas and steam flux than by tracking changes in river solute flux published by elsevier b v

geochemical heterogeneity of sublacustrine hydrothermal vents in yellowstone lake wyoming abstract rov based submersible operations in yellowstone lake yellowstone national park wyoming usa have identified two locations with chemically and mineralogically distinct sublacustrine hydrothermal fluids and deposits the deep hole east of stevenson island si deep hole and the se west thumb deep vent field se wt field the si deep hole is the deepest part of yellowstone lake 120 m and hosts up to 174 c fluids heated by steam that condenses on contact with cold lake water the resulting hot fluids exit through a clay alteration cap that largely consists of kaolinite the si deep hole hydrothermal vents are analogous to steam heated hot springs elsewhere in yellowstone national park ynp e g the mud volcano area which are typified by fumaroles and acid sulfate fluids these deep sublacustrine vent fluids are more aptly termed carbonic acid sulfide owing to a lack substantial sulfate from h2s oxidation and acidity attributed to dissolved co2 at 53 m depth vent fluids at the se wt field achieve temperatures of up to 141 c these neutral chloride fluids are largely similar to those that produce siliceous deposits in many subaerial ynp geyser basins geothermometry calculations and binary mixing relationships indicate the se wt field fluids equilibrated at 207 to 224 c following mixing between oxygenated dilute cold groundwater and a fluid with t 345 to 364 c cl 400 ppm and d 149 vsmow broadly similar to the putative deep parent fluid that supplies most geyser basins in ynp the d values of se wt field fluids cannot be derived from lake water implying km scale lateral hydrothermal fluid flow from outside the boundary of yellowstone lake the fluid compositions and hydrothermal processes operating in the two sublacustrine vent systems are distinct but the overarching influence of magmatic heating complex degassing and alteration mineralization effects are broadly comparable to those that affect their subaerial counterparts the high temperatures and hydrostatic pressures of the sublacustrine vents however provide a window into the evolution of fluid chemistry in more deeply seated and less accessible regions of the subsurface ynp and similar volcanically active hydrothermal systems elsewhere

modeling of co2 driven cold water geyser in the northeast qinghai tibet plateau abstract co2 driven geysers are important natural analogs of co2 leakage in geologic carbon sequestration this study investigated a co2 driven cold water geyser evolved within an abandoned wellbore in the northeast qinghai tibet plateau maintaining a steady eruption period of 330 s and a maximum instantaneous aqueous phase discharge rate of 67 53 kg s based on the geological conditions and wellbore configuration a 3d wellbore reservoir coupled numerical model was developed the simulation results are in good agreement with the experimental data and the co2 emission of the geyser was estimated as 315 36 t yr the mechanism of the periodic eruptions was analyzed by the spatiotemporal variation in various primary variables including pressure temperature gas saturation fluid flow rates and phase velocities within the wellbore and is coherent with the reports by lu et al 2005 watson et al 2014 i e the eruption is controlled by the evolution of flow patterns and the periodicity is regulated by the coupling of the self enhancing and self limiting process the parameter sensitivity analysis indicated that the wellbore diameter reservoir permeability thickness pressure gradient and co2 mass fraction in groundwater have a profound effect on the behavior of the periodic eruptions and these causalities could serve as a reference to identify the direct inducement for the evolution of analogous periodic eruptions

noble gas radionuclides in yellowstone geothermal gas emissions a reconnaissance abstract a reconnaissance investigation of noble gas radionuclides 39 ar 81 kr and 85 kr in gas emissions from several geothermal features at yellowstone national park was performed to explore tracer applications of these nuclides in an active hydrothermal system prior studies of the yellowstone system using stable noble gas isotopes show that the thermal fluids contain a mixture of atmospheric mantle and crustal components noble gas radionuclide measurements provide complementary chronometric information regarding subsurface residence times of thermal fluids from decay of 81 kr and 85 kr as well as in situ production and release of nucleogenic 39 ar and radiogenic 40 ar in the reservoir rock argon 39 isotopic abundances in air corrected samples exceed those of atmospheric ar by 705 to 1217 indicating substantial ar contribution to thermal fluids by fluid rock interaction upper limits on deep thermal fluid mean residence times estimated from 39 ar 40 ar ratios are about 100 kyr for features in the gibbon and norris geyser basin areas and is about 30 kyr in lower geyser basin with the key assumption that the fluid acquires its crustal component of ar in quaternary volcanic rock of the yellowstone caldera input of crustal ar from older aquifer rocks would reduce these apparent mean residence times 81 kr isotopic abundances in the gas samples yield upper limits on residence time that are consistent with those obtained from 39 ar 40 ar ratios

distribution of buried hydrothermal alteration deduced from high resolution magnetic surveys in yellowstone national park yellowstone national park ynp displays numerous and extensive hydrothermal features although hydrothermal alteration in ynp has been extensively studied the volume geometry and type of rock alteration at depth remain poorly constrained in this study we use high resolution airborne and ground magnetic surveys and measurements of remanent and induced magnetization of field and drill core samples to provide constraints on the geometry of hydrothermal alteration within the subsurface of three thermal areas in ynp firehole river smoke jumper hot springs and norris geyser basin we observe that hydrothermal zones from both liquid and vapor dominated systems coincide with magnetic lows observed in aeromagnetic surveys and with a decrease of the amplitude of short wavelength anomalies seen in ground magnetic surveys this suggests a strong demagnetization of both the shallow and deep substratum within these areas associated with the removal of magnetic minerals by hydrothermal alteration processes such demagnetization is confirmed by measurements of rock samples from hydrothermal areas which display significantly decreased total magnetization a pronounced negative anomaly is observed over the lone star geyser and suggests a significant demagnetization of the substratum associated with areas displaying large scale fluid flow the ground and airborne magnetic surveys are used to evaluate the distribution of magnetization in the subsurface this study shows that significant demagnetization occurs over a thickness of at least a few hundred meters in hydrothermal areas at ynp and that the maximum degree or maximum thickness of demagnetization correlates closely with the location of hydrothermal activity and mapped alteration

geothermal gas compositions in yellowstone national park usa abstract gas samples collected between 1974 and 1986 have been analysed for the ten major components samples have been collected almost exclusively from the tops of pools which has degraded the value of the data and limited inter comparisons to the relatively insoluble components ar n 2 ch 4 h 2 and he a general gas distribution pattern in the park in terms of these components shows the major heat source s to underlie the gibbon and mud volcano areas with all other geothermal areas having gas compositions consistent with a general north south water flow shoshone basin gases show a large range of compositions and these are analysed in detail the patterns conform to that which would be expected from an east west flow or fluid with progressive boiling and subsequent dilution

depositional facies and diagenetic alteration in a relict siliceous hot spring accumulation examples from yellowstone national park u s a abstract siliceous precipitates from portions of an 11 m long core drilled through a relict yellowstone hot spring deposit provide valuable insights into the diagenetic facies in this hydrothermal environment most of the core consists of relatively low temperature siliceous sinter containing abundant plant diatom and microbial fossilized remains derived from the distal debris apron and discharge channel flowpath of the hot spring a few intervals contain stromatolitic horizons analogous to modern siliceous pool margin and discharge channel flowpath facies despite the abundance of silicified microbial remains e g silicified stromatolitic horizons as well as individual filamentous microbes diatoms distinctive organic biomarkers are not preserved in the core the apparent lack of distinctive organic biomarkers is attributable to pervasive diagenetic alteration in the presence of high temperature chemically reactive fluids numerous diagenetic features have been superimposed on the siliceous sinter especially considering the relatively shallow depths of burial the uppermost interval 0 to 1 2 m consists of highly porous siliceous sinter opal a and interbedded travertine amorphous manganese oxides and sparry calcite cements are present and are irregularly distributed throughout this interval below is a diagenetic facies 4 8 to 5 3 m that consists of opal ct and minor chalcedony the most pervasive diagenetic alteration in the core is the 6 8 to 11 2 m depth interval where abundant zeolites mordenite heulandite bladed cristobalite lepispheres chalcedony cements and calcite veins are present judging by the assemblage of plant and diatom remains most of this pervasive alteration is superimposed on relatively low temperature siliceous sinters and is likely the result of migration of hot waters through this interval the paragenesis of all these intervals is very complex involving numerous episodes of mineral precipitation and dissolution this diagenetic alteration is facilitated by the porous nature of the siliceous sinter thermal convection of superheated fluids or steam strongly oxidizing spring waters and fluctuating hydrochemical regimes rapid dissolution and or replacement of organic matter indicates that standard morphological means e g petrographic identification of body fossils may be the best method by which to identify that organisms were previously present in ancient hot spring accumulations

seismicity at old faithful geyser an isolated source of geothermal noise and possible analogue of volcanic seismicity abstract old faithful geyser in yellowstone national park u s a is a relatively isolated source of seismic noise and exhibits seismic behavior similar to that observed at many volcanoes including bubblequakes that resemble b type earthquakes harmonic tremor before and during eruptions and periods of seismic quiet prior to eruptions although old faithful differs from volcanoes in that the conduit is continuously open that rock fracturing is not a process responsible for seismicity and that the erupting fluid is inviscid h2o rather than viscous magma there are also remarkable similarities in the problems of heat and mass recharge to the system in the eruption dynamics and in the seismicity water rises irregularly into the immediate reservoir of old faithful as recharge occurs a fact that suggests that there are two enlarged storage regions one between 18 and 22 m the base of the immediate reservoir and one between about 10 and 12 m depth transport of heat from hot water or steam entering at the base of the recharging water column into cooler overlying water occurs by migration of steam bubbles upward and their collapse in the cooler water and by episodes of convective overturn an eruption occurs when the temperature of the near surface water exceeds the boiling point if the entire water column is sufficiently close to the boiling curve that the propagation of pressure release waves rarefactions down the column can bring the liquid water onto the boiling curve the process of conversion of the liquid water in the conduit at the onset of an eruption into a two phase liquid vapor mixture takes on the order of 30 s the seismicity is directly related to the sequence of filling and heating during the recharge cycle and to the fluid mechanics of the eruption short 0 2 0 3 s monochromatic high frequency events 20 60 hz resembling unsustained harmonic tremor and in some instances b type volcanic earthquakes occur when exploding or imploding bubbles of steam cause transient vibrations of the fluid column the frequency of the events is determined by the length of the water column and the speed of sound of the fluid in the conduit when these events occur damping is controlled by the characteristic and hydraulic impedances which depend on the above parameters as well as on the recharge rate of the fluid two periods of reduced seismicity of a few tens of seconds to nearly a minute in duration occur during the recharge cycle apparently when the water rises rapidly through the narrow regions of the conduit causing a sudden pressure increase that temporarily suppresses steam bubble formation a period of decreased seismicity also precedes preplay or an eruption this appears to be the time when rising steam bubbles move into a zone of boiling that is acoustically decoupled from the wall of the conduit because of the acoustic impedance mismatch between boiling water c 10 3 g cm 2 s 1 and rock c 3 10 5 g cm 2 s 1 sustained harmonic tremor occurs during the first one to one and a half minutes of an eruption of old faithful but is not detectable in the succeeding minutes of the eruption the eruption tremor is caused by hydraulic transients propagating within a sublayer of unvesiculated water that underlies the erupting two phase liquid vapor mixture the resonant frequencies of the fluid column decrease to about 1 hz when all of the water in the conduit has been converted to a water steam mixture surges are observed in the flow at this frequency but the resonance has not been detected seismically possibly because the two phase erupting fluid is seismically decoupled from the rock on which seismometers are placed if old faithful is an analogue for volcanic seismicity this study shows that because the frequency of tremor depends on the acoustic properties of the fluid and on conduit dimensions both properties must be considered in analysis of tremor in volcanic regions because magma sound speed can vary over nearly two orders of magnitude as it changes from an undersaturated liquid into a saturated two phase mixture tremor frequency might vary by this magnitude and very broad band seismographs may be required if tremor is to be monitored as magma goes from an undersaturated liquid to a vesiculated froth cessation of fluid induced seismicity may indicate that the processes that drive the transients cease but it is also possible that the processes that drive the transients continue but the fluid properties change so that the fluid becomes acoustically decoupled from the rock on which seismometers are placed