deformation of the long valley caldera eastern california from mid 1983 to mid 1988 measurements using a two color geodimeter deformation of long valley caldera in eastern california has been closely monitored since june 1983 with a two color geodimeter which has a precision between 0 12 and 0 20 ppm of the baseline length initial trilateration measurements were concentrated in the south moat of the caldera the source of the january 1983 earthquake swarm since then the network has been expanded from 13 to 42 baselines the additional baselines span the resurgent dome and the western half of the caldera with a combination of measurements made several times per week on 7 11 baselines and monthly or yearly measurements on the remaining baselines we have measured both the temporal and spatial deformation of the caldera although the m 6 4 chalfant valley earthquake was located 35 km from the nearest baseline in the network we observed coseismic strain changes of up to 1 5 ppm on several baselines using fault planes selected to coincide with the hypo centers of the main shock and the m 5 9 foreshock we have inferred a combined moment of 3 0 1025 dyn cm from the two color data this cumulative moment of both earthquakes is equivalent to a magnitude 6 3 shock over the period from mid 1983 to mid 1988 the long term trends determined from the length changes of the baselines within the caldera show a general decrease in the rate of extension during 1983 measurements show a maximum extension rate of 5 0 ppm yr after mid to late 1984 the extension rates decreased by a factor of 2 4 relative to those in the first year with the exception of the coseismic step the extension rates have been fairly constant during the interval between late 1984 and mid 1988 the long term changes in rate can be modeled by using two mogi point sources representing inflation beneath the resurgent dome of the caldera and a dislocation surface representing slip in the south moat modeling indicates that both the rates of slip and inflation have decreased since mid 1983 but these two processes are still occurring at a measureable and constant rate

dynamics of carbon dioxide emission at mammoth mountain california mammoth mountain a dormant volcano in the eastern sierra nevada california has been passively degassing large quantities of cold magmatic co2 since 1990 following a 6 month long earthquake swarm associated with a shallow magmatic intrusion in 1989 a search for any link between gas discharge and volcanic hazard at this popular recreation area led us to initiate a detailed study of the degassing process in 1997 our continuous monitoring results elucidate some of the physical controls that influence dynamics in flank co2 degassing at this volcano high coherence between variations in co2 efflux and variations in atmospheric pressure and wind speed imply that meteorological parameters account for much if not all of the variability in co2 efflux rates our results help explain differences among previously published estimates of co2 efflux at mammoth mountain and indicate that the long term annual co2 degassing rate has in fact remained constant since 1997 discounting the possibility of large meteorologically driven temporal variations in gas efflux at other volcanoes may result in spurious interpretations of transients that do not reflect actual geologic processes

study of volcanic sources at long valley caldera california using gravity data and a genetic algorithm inversion technique we model the source inflation of the long valley caldera california using a genetic algorithm technique and micro gravity data while there have been numerous attempts to model the magma injection at long valley caldera from deformation data this has proven difficult given the complicated spatial and temporal nature of the volcanic source recent work illustrates the effectiveness of considering micro gravity measurements in volcanic areas a genetic algorithm is a problem solving technique which combines genetic and prescribed random information exchange we perform two inversions one for a single spherical point source and another for two sources that might represent a more spatially distributed source the forward model we use to interpret the results is the elastic gravitational earth model which takes into account the source mass and its interaction with the gravity field the results demonstrate the need to incorporate more variations in the model including another source geometry and the faulting mechanism in order to provide better constraints on intrusion volumes future work should include the joint inversion of gravity and deformation data during the same epoch

co 2 degassing in the hartousov mofette area western eger rift imaged by co 2 mapping and geoelectrical and gravity surveys strong subcontinental mantle dominated co2 degassing occurs in the hartousov and bublak mofette fields in the western eger rift the combination of co2 gas flux and soil gas measurements as well as gravity and geoelectric surveys provides insight into the surface and subsurface of this unique mofette area co2 soil gas and gas flux measurements reveal that large amounts of carbon dioxide are released via channels with diameters below 1 m carbon dioxide emissions of several tens and up to more than 100 kg day 1 are ejected via these small seeps measurements with small spacings are necessary to account for the point like focused gas discharge in the lesser degassing surrounding we estimate that between 23 and 97 tons of co2 are released over an area of about 350 000 m2 each day in the hartousov mofette field the application of widely used geostatistical tools leads to estimations of the co2 discharge with very high standard deviations due to the strong positive skewness of the data distribution geophysical investigations via electrical resistivity tomography and gravity measurements were carried out over areas of strong seepage and reveal distinct anomalies in the subsurface below mofettes indicating rock and sediment alterations and or sediment transport by pressurised ascending co2 and water mobilised by it this study reveals that the gas emanations only occur west of a morphological step which is related to a n s oriented fault zone the pocatky plesna fault zone the results of co2 mapping and the geophysical studies can track the course of this fault zone in this area our results fit into a tectonic model in which the mofette fields are in the centres of two independent pull apart basin like structures we hypothesise that the sinistral strike slip movement of the pocatky plesna fault zone leads to a pull apart basin like opening at which the strong mantle derived co2 degassing occurs nowadays since the hartousov and bublak mofette fields only illustrate examples along the n s striking pocatky plesna fault zone its role and other n s striking faults roles of the regensburg leipzig rostock zone for upper mantle degassing might have been underestimated previously

a comparison of shear and buoyancy driven planetary boundary layer flows abstract planetary boundary layer pbl flows are known to exhibit fundamental differences depending on the relative combination of wind shear and buoyancy forces these differences are not unexpected in that shear instabilities occur locally while buoyancy force sets up vigorous thermals which result in nonlocal transport of heat and momentum at the same time these two forces can act together to modify the flow field in this study four large eddy simulations less spanning the shear and buoyancy flow regimes were generated two correspond to the extreme cases of shear and buoyancy driven pbls while the other two represent intermediate pbls where both forces are important the extreme cases are used to highlight and quantify the basic differences between shear and convective pbls in 1 flow structures 2 overall statistics and 3 turbulent kinetic energy tke budget distributions results from the two intermediate les cases are used to develop and verify a velocity scaling and a tke budget mode

open fissure mineralization at 2600 m depth in long valley exploratory well california insight into the history of the hydrothermal system abstract long valley exploratory well drilled into the resurgent dome at long valley caldera california to explore the potential of geothermal power in an active magmatic system achieved temperatures of only ca 100 c at 2500 3000 m depth well below the range expected atop an active magma chamber open fissures encountered at 2600 m depth are coated by mm sized idiomorphic quartz crystals with first and second order growth discontinuities specific growth defects indicating rapid crystallization reflect sudden changes in sio 2 supersaturation fluid inclusions contain low salinity 0 5 wt nacl and low co 2

environmental isotope study of seawater intrusion in the coastal aquifer syria seawater intrusion into the shallow aquifer in the syrian coast north of latakia damsarkho ras ibn hani and south of tartous al hamidieh ein zarka was studied using hydrochemical and isotopic techniques the electrical conductivity ec distribution map north of latakia revealed that mixing in this area is the consequence of a frontal intrusion of seawater within the fresh groundwater aquifer which in turn results from intensive pumping since the 1960s which has lowered the water table inland below sea level in ein zarka south of tartous in contrast the ec distribution revealed that seawater intrusion is due to local up coning as a result of intensive pumping the deuterium and oxygen 18 relationship is that of a mixing line with a slope of 5 55 indicating an intrusion between freshwater and seawater in addition the relationship between oxygen 18 and chloride reveals that the mixing has a dominant role compared to evaporation process the mixing ratios are estimated to be between 6 and 10 north of latakia while they do not exceed 3 south of tartous a tritium model was applied to compute the mean transit time which is estimated to be around 10 years on average to reach the equilibrium that existed originally between the fresh groundwater and seawater provided that severe pumping is completely halted and the aquifer is naturally recharged by rainfall and deep percolation of irrigation water thereby allowing the restoration of the hydraulic gradient

new results at mayon philippines from a joint inversion of gravity and deformation measurements in this paper we detail the combination of the genetic algorithm ga inversion technique with the elastic gravitational model originally developed by rundle and subsequently refined by fernandez and others a sensitivity analysis is performed for the joint inversion of deformation and gravity to each of the model parameters illustrating the importance of proper identification of both the strengths and limitations of any source model inversion and this technique in particular there is a practical comparison of the theoretical results with the inversion of geodetic data observed at the mayon volcano in the philippines where there are gravity changes without significant deformation after the 1993 eruption

convective structures in a cold air outbreak over lake michigan during lake ice abstract the lake induced convection experiment provided special field data during a westerly flow cold air outbreak cao on 13 january 1998 which has afforded the opportunity to examine in detail an evolving convective boundary layer vertical cross sections prepared from these data extending from upstream over wisconsin out across lake michigan show the modifying effects of land water contrast on boundary layer mixing entrainment heating and moisture flux through this analysis an interesting case of lake effect airmass modification was discovered the data show atypical differing heights in vertical mixing of heat and moisture as well as offshore downwelling and subsidence effects in the atmosphere analysis shows evidence of a new observational feature the moisture internal boundary layer mibl that accords well with the often recognized thermal internal boundary layer tibl the interfacial layer over the lake is also found to be unusually thick and moist due in part to the upstream co

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

the influence of large convective eddies on the surface layer turbulence summary close to the surface large coherent eddies consisting of plumes and downdraughts cause convergent winds blowing towards the plume axes which in turn cause wind shears and generation of turbulence this mechanism strongly enhances the convective heat mass transfer at the surface and in contrast to the classical formulation implies an important role of the surface roughness in this context we introduce the stability dependence of the roughness length the latter is important over very rough surfaces when the height of the roughness elements becomes comparable with the large eddy monin obukhov length a consistent theoretical model covering convective regimes over all types of natural surfaces from the smooth still sea to the very rough city of athens is developed it is also comprehensively validated against data from measurements at different sites and also through the convective boundary layer good correspondence between model results field observations and large eddy simulation is achieved over a wide range of surface roughness lengths and convective boundary layer heights

fluid flow in the resurgent dome of long valley caldera implications from thermal data and deep electrical sounding abstract temperatures of 100 c are measured at 3 km depth in a well located on the resurgent dome in the center of long valley caldera california despite an assumed 800 c magma chamber at 6 8 km depth local downflow of cold meteoric water as a process for cooling the resurgent dome is ruled out by a peclet number analysis of temperature logs these analyses reveal zones with fluid circulation at the upper and lower boundaries of the bishop tuff and an upflow zone in the metasedimentary rocks vertical darcy velocities range from 10 to 70 cm a 1 a 21 km long geoelectrical profile across the caldera provides resistivity values to the order of 10 0 to 10 3 m down to a depth of 6 km as well as variations of self potential interpretation of the electrical data with respect to hydrothermal fluid movement confirms that there is no downflow beneath the resurgent dome to explain the unexpectedly low temperatures in the resurgent dome we challenge the common view that the caldera as a whole is a regime of high temperatures and the resurgent dome is a local cold anomaly instead we suggest that the caldera was cooled to normal thermal conditions by vigorous hydrothermal activity in the past and that a present day hot water flow system is responsible for local hot anomalies such as hot creek and the area of the casa diablo geothermal power plant the source of hot water has been associated with recent shallow intrusions into the west moat the focus of planning for future power plants should be to locate this present day flow system instead of relying on heat from the old magma chamber

considerations for measuring ground co2 effluxes with chambers abstract this paper considers the factors that influence ground co 2 fluxes as measured by the chamber method new data and published results are used to illustrate the effects of various factors on co 2 emissions from the ground these factors are pressure differences between the ambient air and the chamber wind speed within the chamber the chamber co 2 concentration relative to ambient air concentration and the accumulation of water vapor in the chamber a mathematical analysis of the accumulation of co 2 in the chamber in terms of diffusion and advection e g air flow out of the ground at geothermal degassing locations shows that the same protocol should be followed whether the mechanism of emission is purely by diffusion or by a combination of diffusion and advection the analysis also yields a simple way for estimating soil co 2 conductance and the soil co 2 concentration at the depth of insertion of the chamber into the ground

a new velocity field for africa from combined gps and doris space geodetic solutions contribution to the definition of the african reference frame afref 1 we analyzed 16 years of gps and 17 years of doppler orbitography and radiopositioning integrated by satellite doris data at continuously operating geodetic sites in africa and surroundings to describe the present day kinematics of the nubian and somalian plates and constrain relative motions across the east african rift the resulting velocity field describes horizontal and vertical motion at 133 gps sites and 9 doris sites horizontal velocities at sites located on stable nubia fit a single plate model with a weighted root mean square residual of 0 6 mm yr maximum residual 1 mm yr an upper bound for plate wide motions and for regional scale deformation in the seismically active southern africa and cameroon volcanic line we confirm significant southward motion 1 5 mm yr in morocco with respect to nubia consistent with earlier findings we propose an updated angular velocity for the divergence between nubia and somalia which provides the kinematic boundary conditions to rifting in east africa we update a plate motion model for the east african rift and revise the counterclockwise rotation of the victoria plate and clockwise rotation of the rovuma plate with respect to nubia vertical velocities range from 2 to 2 mm yr close to their uncertainties with no clear geographic pattern this study provides the first continent wide position velocity solution for africa expressed in international terrestrial reference frame itrf2008 a contribution to the upcoming african reference frame afref except for a few regions the african continent remains largely under sampled by continuous space geodetic data efforts are needed to augment the geodetic infrastructure and openly share existing data sets so that the objectives of afref can be fully reached

sensitivity of crustal deformation instruments to changes in secular rate a variety of instruments including borehole strainmeters water wells creepmeters laser ranging and differential magnetometers are used to monitor crustal deformation in areas that are prone to geologic hazards such as earthquakes and volcanic eruptions in monitoring the deformation one typically examines the data for either a change in rate or a simple offset in the record however one needs to place a statistical confidence level that the detected signal differs from the background noise calculation of the statistical confidence level may be done using the formalism of the matched filter whose output is the signal to noise ratio two ingredients are needed to form a matched filter 1 the power density spectrum of the instrument and 2 the functional form of the signal that we desire to detect using the available crustal deformation data from the parkfield california network the background noise for individual instruments as a function of frequency f is estimated using the traditional method of the power density spectra except for two color laser distance ranging data the power spectra for most of the instruments have a frequency dependence of f n where 2 n 3 the confidence level with which a hypothesized signal is present is determined directly from the signal to noise ratio with the numerator being a function of the signal and the denominator being a function of the power spectrum using a creepmeter as an example a 0 04 mm change occurring over 1 hour a 0 06 mm occurring over 10 hours or 0 20 mm over 100 hours are all signals for which 2 and therefore have only a 5 confidence that these signals could be background noise

carbon dioxide emissions from vegetation kill zones around the resurgent dome of long valley caldera eastern california usa abstract a survey of diffuse co2 efflux soil temperature and soil gas chemistry over areas of localized vegetation kill on and around the resurgent dome of long valley caldera california was performed to evaluate the premise that gaseous and thermal anomalies are related to renewed intrusion of magma some kill sites are long lived features and others have developed in the past few years total anomalous co2 emissions from the thirteen areas average around 8 7 t per day but the majority of the emissions come from four sites west of the casa diablo geothermal power plant geochemical analyses of the soil gases from locations west and east of the plant revealed the presence of isobutane related to plant operations the 13c values of diffuse co2 range from 5 7 to 3 4 similar to values previously reported for co2 from hot springs and thermal wells around long valley at many of the vegetation kill sites soil temperatures reach boiling at depths 20 cm soil temperature depth profiles at two of the high emissions areas indicate that the conductive thermal gradient in the center of the areas is around 320 c m 1 we estimate total heat loss from the two areas to be about 6 1 and 2 3 mw given current thinking on the rate of hydrothermal fluid flow across the caldera and using the co2 concentration in the thermal fluids the heat and co2 loss from the kill areas is easily provided by the shallow hydrothermal system which is sourced to the west of the resurgent dome we find no evidence that the development of new areas of vegetation kill across the resurgent dome are related to new input of magma or magmatic fluids from beneath the resurgent dome our findings indicate that the areas have developed as a response to changes in the shallow hydrologic system some of the changes are likely related to fluid production at the power plant but at distal sites the changes are more likely related to seismicity and uplift of the dome

near real time field measurements of δ 13 c in co 2 from volcanoes this paper describes the operation and application of a portable cavity ring down spectrometer crds designed to measure the isotopic composition of carbon dioxide the instrument is capable of measuring 13c for co2 concentrations ranging from atmospheric 400 ppm to 100 at precisions and accuracies that are comparable to laboratory based gas source mass spectrometers this flexibility and portability are ideal for applications on active volcanoes and it is now possible to obtain isotopic measurements on a near real time basis we show applications of the crds for soil gases on volcanoes and in calderas for characterizing the isotopic composition of a volcanic plume and for measuring the temporal variability of 13c in the atmosphere future directions hold the potential to use volcanic gas isotopes for monitoring purposes and to combine different isotopic systems to reveal the source or sources of gas

inversion for p and s wave attenuation structure long valley caldera california p and s wave amplitude data from digital three component seismograms of local earthquakes recorded on a temporary seismic array have been used to tomographically invert for the three dimensional attenuation structure in the upper crust of long valley caldera california differential attenuation q 1 values are obtained through the use of a spectral ratio technique that minimizes the site effect on the spectral ratios the spectral ratios are inverted for q 1 using the lsqr algorithm zones of high positive p wave q 1 greater p wave attenuation are observed at a depth of 4 5 km beneath the east flank of mammoth mountain and at 6 8 km beneath the southwestern edge of the resurgent dome a region of positive s wave q 1 is seen at 7 8 km beneath the southern edge of the resurgent dome whereas at 6 7 km the s wave results are near average the region of positive s wave q 1 at 7 8 km beneath the resurgent dome may indicate the roof of a magmatic system the positive p wave q 1 at 4 5 km beneath mammoth mountain and 6 8 km beneath the resurgent dome may be due to the presence of a compressible fluid such as supercritical water these zones may represent some of the source regions for the long valley geothermal system

inflation of long valley caldera california basin and range strain and possible mono craters dike opening from 1990 94 gps surveys five years of annual global positioning system gps surveys of a network centered on long valley california constrain displacement rates for these stations relative to a central station in the network these observations are consistent with recent models of resurgent dome inflation in long valley langbein et al 1995 and have sufficient signal to detect the presence of basin and range strain in the long valley region the data also allow for the possibility of dike inflation beneath the mono craters dike intrusion is consistent with the mono craters recent geologic history of ash eruptions with seismic tomography leveling data and geologic studies of these volcanic domes and flows

sombrero uplift above the altiplano puna magma body evidence of a ballooning mid crustal diapir the altiplano puna ultralow velocity zone in the central andes south america is the largest active magma body in earth s continental crust space geodetic observations reported an uplift in the altiplano puna proper at a rate of 10 mm year however the nature of the inferred inflation source has been uncertain we present data showing that the uplift has persisted at a nearly constant rate over the past two decades and is surrounded by a broad zone of subsidence we show that the ongoing uplift and peripheral subsidence may result from a large mid crustal diapir fed by partial melt from the altiplano puna magma body

spherical and ellipsoidal volcanic sources at long valley caldera california using a genetic algorithm inversion technique abstract we model the second inflation period at long valley caldera california using a genetic algorithm technique and high quality geodetic measurements of elevation changes and baseline extensions we compare two source inversions for both spherical mogi point sources and the finite prolate ellipsoid of yang and davis a sensitivity analysis for the genetic algorithm is performed based upon synthetic data set inversions on similar sources in order to better constrain the areal location orientation and volume of the potential sources the spherical sources are well constrained the larger located at 9 9 km beneath the resurgent dome with a volume of 0 036 km 3 while the second at only 0 008 km 3 is located at a depth of 7 3 km beneath the south moat the depths to the ellipsoidal sources are switched with the larger source at a depth of 9 6 km and the smaller at 11 8 km with volumes of 0 037 and 0 002 km 3 respectively

analysis of two color geodimeter measurements of deformation within the long valley caldera june 1983 to october 1985 line length changes from several baselines in a trilateration network within the long valley caldera clearly define a decrease in strain rate from june 1983 through october 1985 the data consist of more than 1600 length measurements on 23 baselines using a two color geodimeter which has a precision of 0 2 ppm of the line length initial measurements made during the summer of 1983 show extension rates were as high as 6 ppm yr on some baselines the rates subsequently decreased steadily to less than 1 ppm yr during the summer of 1985 ih contrast the strain rates on a few other baselines were less than 0 2 ppm yr averaged over the 2 3 year interval a model is constructed using these observations as well as yearly observations of a trilateration network within and near the caldera the model contains two points of inflation located at 5 and 10 km beneath the resurgent dome of the caldera plus dextral slip on a fault plane within the south moat within an elastic half space to mimic the observed time dependence in the two color geodimeter data we conclude that the rates of both slip and inflation have steadily decreased over the survey interval because the two color geodimeter network is closer to all three sources than the single color geodimeter network these data are important for defining the factor of 2 3 rate decrease of slip and inflation comparing our estimates of slip and inflation with similar estimates for the year prior to july 1983 we conclude that the rate decrease is probably a result of postseismic and postinflation relaxation following the earthquake swarm in the south moat in january 1983

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

changes in hydraulic conductivity of laboratory sand clay mixtures caused by a seawater freshwater interface abstract the influence of small amounts of clay minerals on the hydraulic conductivity of sandy aquifer was investigated by laboratory experiments admixture of up to 1 5 by weight of clay minerals to sand did not cause any measurable decrease of hydraulic conductivity for seawater increasing the clay fraction from 1 5 to 10 decreased hydraulic conductivity by one order of magnitude montmorillonite caused the strongest decrease the effect of kaolinite and illite was only half as large when seawater was flushed by freshwater hydraulic conductivity of the montmorillonite sand mixture decreased drastically however flushing with freshwater did not measurably affect the hydraulic conductivity of an illite sand or kaolinite sand mixture the explanation for this behaviour is the capability of various types of clay to adsorb different quantities of water between their platelets which induces a gel droplet formation process this is governed by the chemical composition and the ionic strength of the solution

observations of the entrainment zone in a rapidly entraining boundary layer high rate turbulence data collected by the national center for atmospheric research electra aircraft on 13 january 1998 over lake michigan during the lake induced convection experiment are analyzed to explore the turbulence dynamics of the entrainment zone of a rapidly entraining convective boundary layer horizontal flight legs combined with the gentle slope of the lake enhanced boundary layer top yield high resolution profiles through the entrainment zone data analysis used a new maximally overlapping subleg reynolds decomposition algorithm to compute first second and third moment statistics for each flight leg then a compositing algorithm using 25 bins took like statistics from each flight leg and created smoothly varying curves that captured the variation of each statistic across the upper mixed layer and entrainment zone the analysis results reveal a conventional convective boundary layer below and a nonturbulent free atmosphere above a well resolved entrainment zone in the entrainment zone temperature and moisture skewness curves show that the last identifiable free atmosphere effects extend down well below the zero crossing of heat flux third moment statistics reveal considerable height dependence of the entrainment zone dynamics

observations of vertical velocity skewness within the marine stratocumulus topped boundary layer abstract during june and july 1987 the first isccp international satellite cloud climatology project regional experiment fire was conducted within the marine stratocumulus topped boundary layer off the coast of california one of the goals of the experiment was to investigate the structure of turbulent convection within the fire boundary layers the skewness of vertical velocity has proven to be a very useful statistic in the quest to understand this structure profiles of vertical velocity skewness from three turbulence flights conducted during fire are presented here these three flights were chosen because each represents a distinctly different pattern of vertical velocity skewness the observations of vertical velocity skewness from each of these flights are compared to the skewness statistics derived from a large eddy simulation les of a boundary layer whose profile of buoyancy flux is qualitatively similar to that found on the given fire flight plausible explanations are put forward in an eff

displacement of surface monuments horizontal motion measurements of tectonic deformation depend on both accurate instrumentation and adequate coupling of the apparatus to the earth s crust existing techniques capable of resolving the signals of interest strain rates of 10 n yr are mainly observatory based the limitation in the baselength of these instruments 1 km results in a requirement that the reference monuments be exceptionally stable 10 tzm yr however records from pition flat observatory california show that the actual horizontal displacements for massive near surface monuments eraplaced in competent weathered granite are of the order of 50 tzm yr the low noise level of the strain measurements at this site indicates that this magnitude of monument displacement is abnormally small until high accuracy geodetic techniques are developed sophisticated monuments or monument monitoring devices will be necessary to record faithfully continuous crustal deformation

diffuse emission of carbon dioxide from cerro negro volcano nicaragua central america we report the first detailed soil co2 efflux survey carried out at cerro negro volcano nicaragua central america soil co2 efflux values ranged from 0 5 to 35 000 g m 2 d 1 spatial distribution of co2 efflux shows that volcanic gas is mainly released from the summit crater and the fissures opened during the august 1999 eruption the total co2 output of cerro negro is conservatively estimated to be 2 800 t d 1 based on a study area of 0 58 km contour maps of soil co2 efflux ground temperature and 13c co2 distributions support an important magmatic contribution for the total output of co2 at cerro negro volcano

dynamics of active magmatic and hydrothermal systems at taal volcano philippines from continuous gps measurements 1 a dense network of continuous single and dual frequency gps receivers at taal volcano philippines reveals four major stages of volcanogenic deformation deflation from installation in june 1998 to december 1998 inflation from january to march 1999 deflation from april 1999 to february 2000 and inflation from february to november 2000 the largest displacements occurred during the february november 2000 period of inflation which was characterized by 120 mm of uplift of the center of volcano island relative to the northern caldera rim at average rates up to 216 mm yr deformation sources were modeled using a constrained least squares inversion algorithm the source of 1999 deflation and inflation in 2000 were modeled as contractional and dilatational mogi point sources centered at 4 2 and 5 2 km depth respectively beneath volcano island the locations of the inflationary and deflationary sources are indistinguishable within the 95 confidence estimates modeling using a running 4 month time window from june 1999 to march 2001 reveals little evidence for source migration we suggest that the two periods of inflation observed at taal result from episodic intrusions of magma into a shallow reservoir centered beneath volcano island subsequent deflation may result from exsolution of magmatic fluids and or gases into an overlying unconfined hydrothermal system

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

les model sensitivities to domains grids and large eddy timescales abstract this study has addressed the sensitivity of large eddy simulation les models to domain size grid resolution and the number of large eddy turnover times t of integration and their respective effects on the characteristic turbulence statistics computed from the simulation of convective flows in planetary boundary layers pbls this includes the review of relevant results from past les studies as well as new findings using les models for type i cloud topped boundary layers with ice and snow horizontal domains in this study were varied from 5 km 5 km to 10 km 10 km grid length varied from 125 m 125 m to 78 m 78 m and three t times of 11 15 and 19 adequate results for horizontal variance were obtained for the 10 km 10 km domain the 78 m 78 m grid and all the t values based on the evaluation criteria introduced to replace the time averaging methodology similar results were found for vertical velocity skewness however 19t offered improvement over 11t and 15t showi

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

summary of recent research in long valley caldera california abstract since 1978 volcanic unrest in the form of earthquakes and ground deformation has persisted in the long valley caldera and adjacent parts of the sierra nevada the papers in this special volume focus on periods of accelerated seismicity and deformation in 1980 1983 1989 1990 and 1997 1998 to delineate relations between geologic tectonic and hydrologic processes the results distinguish between earthquake sequences that result from relaxation of existing stress accumulation through brittle failure and those in which brittle failure is driven by active intrusion they also indicate that in addition to a relatively shallow 7 10 km source beneath the resurgent dome there exists a deeper 15 km source beneath the south moat analysis of microgravimety and deformation data indicates that the composition of the shallower source may involve a combination of silicic magma and hydrothermal fluid pressure and temperature fluctuations in wells have accompanied periods of crustal unrest and additional pressure and temperature changes accompanying ongoing geothermal power production have resulted in land subsidence the completion in 1998 of a 3000 m deep drill hole on the resurgent dome has provided useful information on present and past periods of circulation of water at temperatures of 100 200 c within the crystalline basement rocks that underlie the post caldera volcanics the well is now being converted to a permanent geophysical monitoring station

experimental investigation on irreversible changes of hydraulic conductivity on the seawater freshwater interface in coastal aquifers seawater and fresh groundwater were made to flow through columns filled with samples from a good aquifer that contained 5 or less clay minerals hydraulic conductivities decreased very sharply whenever seawater was flushed by fresh groundwater the extent of the decrease depended mainly on the percentage of clays and reached maximum values of 10 1 to 10 3 of the original hydraulic conductivity subsequent flushing with seawater restored hydraulic conductivity only in a slight measure if at all the mechanism of this process was investigated by using cacl2 and nacl solutions with the ionic strengths of seawater and fresh groundwater it appears that the decrease of hydraulic conductivity is caused by an incipient stage of gel formation the small water clay configurations that are formed during this stage behave as practically rigid particles and close the bottlenecks between adjacent pores the major implications of these findings for groundwater hydrology are as follows 1 in natural coastal aquifers the seawater freshwater interface is likely to undergo shifts on a semigeologic time scale if the aquifer contains even a small percentage of clays these shifts may create an almost impermeable boundary in the zone of the interface hitherto existing theories on movements of the interface regard permeability as constant 2 the attempt to repel a fresh water seawater interface by the injection of fresh water may create a practically impermeable boundary within a relatively short time and thus defeat its own purpose

boundary layer and mesoscale structure over lake michigan during a wintertime cold air outbreak abstract an investigation of a cloud topped boundary layer during a wintertime cold air outbreak over lake michigan has been conducted based on research aircraft 1 and 20 hz data for five vertically stacked levels within the boundary layer mean east west cross sections for this northerly flow event have been prepared for heat moisture and momentum fields along with spectral decomposition and turbulent flux statistics results have been interpreted on the basis of three generalized spatial domains mesoscale 5 km large eddies from 100 m to 5 km and higher frequency turbulence 100 m mesoscale structures identified in the mean cross sections include the lower michigan land breeze a strong offshore convergence snow band cloud streets and precipitation bands over the lake and entrainment spikes in the vicinity of the inversion layer analyses of particle concentrations sizes and liquid water content have also been presented in mean cross sections which correspond well with all identifiable mesos

surface heat flow and co2 emissions within the ohaaki hydrothermal field taupo volcanic zone new zealand abstract carbon dioxide emissions and heat flow have been determined from the ohaaki hydrothermal field taupo volcanic zone tvz new zealand following 20 a of production 116 mw e soil co 2 degassing was quantified with 2663 co 2 flux measurements using the accumulation chamber method and 2563 soil temperatures were measured and converted to equivalent heat flow w m 2 using published soil temperature heat flow functions both co 2 flux and heat flow were analysed statistically and then modelled using 500 sequential gaussian simulations forty subsoil co 2 gas samples were also analysed for stable c isotopes following 20 a of production current co 2 emissions equated to 111 6 7 t d observed heat flow was 70 6 4 mw compared with a pre production value of 122 mw this 52 mw reduction in surface heat flow is due to production induced drying up of all alkali cl outflows 61 5 mw and steam heated pools 8 6 mw within the ohaaki west thermal area ohw the drying up of all alkali cl outflows at ohaaki means that the soil zone is now the major natural pathway of heat release from the high temperature reservoir on the other hand a net gain in thermal ground heat flow of 18 mw from 25 mw to 43 3 5 mw at ohw is associated with permeability increases resulting from surface unit fracturing by production induced ground subsidence the ohaaki east ohe thermal area showed no change in distribution of shallow and deep soil temperature contours despite 20 a of production with an observed heat flow of 26 7 3 mw and a co 2 emission rate of 39 3 t d the negligible change in the thermal status of the ohe thermal area is attributed to the low permeability of the reservoir beneath this area which has limited production mass extraction and sheltered the area from the pressure decline within the main reservoir chemistry suggests that although alkali cl outflows once contributed significantly to the natural surface heat flow 50 they contributed little 2 emissions due to the loss of 99 of the original co 2 content due to depressurisation and boiling as the fluids ascended to the surface consequently the soil has persisted as the major 99 pathway of co 2 release to the atmosphere from the high temperature reservoir at ohaaki the co 2 flux and heat flow surveys indicate that despite 20 a of production the variability in location spatial extent and magnitude of co 2 flux remains consistent with established geochemical and geophysical models of the ohaaki field at both ohw and ohe carbon isotopic analyses of soil gas indicate a two stage fractionation process for moderate flux 60 g m 2 d 1 sites boiling during fluid ascent within the underlying reservoir and isotopic enrichment as co 2 diffuses through porous media of the soil zone for high flux sites 300 g m 2 d 1 the 13 co 2 signature 7 4 0 3 ohw and 6 5 0 6 ohe is unaffected by near surface soil zone fractionation processes and reflects the composition of the boiled magmatic co 2 source for each respective upflow flux thresholds of 2 d 1 for purely diffusive gas transport between 30 and 300 g m 2 d 1 for combined diffusive advective transport and 300 g m 2 d 1 for purely advective gas transport at ohaaki were assigned 13 co 2 values and cumulative probability plots of co 2 flux data both identified a threshold of 15 g m 2 d 1 by which background atmospheric and soil respired co 2 may be differentiated from hydrothermal co 2

a sr isotopic comparison between thermal waters rocks and hydrothermal calcites long valley caldera california abstract the 87 sr 86 sr values of thermal waters and hydrothermal calcites of the long valley caldera geothermal system are more radiogenic than those of young intracaldera volcanic rocks five thermal waters display 87 sr 86 sr of 0 7081 0 7078 but show systematically lighter values from west to east in the direction of lateral flow we believe the decrease in ratio from west to east signifies increased interaction of deeply circulating thermal water with relatively fresh volcanic rocks filling the caldera depression all types of pre syn and post caldera volcanic rocks in the west and central caldera have 87 sr 86 sr m between about 0 7060 and 0 7072 and values for sierra nevada granodiorites adjacent to the caldera are similar sierran pre intrusive metavolcanic and metasedimentary rocks can have considerably higher sr isotope ratios 0 7061 0 7246 and 0 7090 0 7250 respectively hydrothermally altered volcanic rocks inside the caldera have 87 sr 86 sr m slightly heavier than their fresh volcanic equivalents and hydrothermal calcites 0 7068 0 7105 occupy a midrange of values between the volcanic plutonic rocks and the sierran metamorphic rocks these data indicate that the long valley geothermal reservoir is first equilibrated in a basement complex that contains at least some metasedimentary rocks reequilibration of sr isotope ratios to lower values occurs in thermal waters as convecting geothermal fluids flow through the isotopically lighter volcanic rocks of the caldera fill

the 1989 earthquake swarm beneath mammoth mountain california an initial look at the 4 may through 30 september activity abstract mammoth mountain is a 50 000 to 200 000 year old cumulovolcano standing on the southwestern rim of long valley in eastern california on 4 may 1989 two m 1 earthquakes beneath the south flank of the mountain marked the onset of a swarm that has continued for more than 6 months in addition to its longevity noteworthy aspects of this persistent swarm include 1 an exponential like increase in the rate of activity through the first month 2 a vertically oriented planar distribution of hypocenters at depths between 6 and 9 km with a north northeast strike roughly perpendicular to the average t axis orientation for the swarm earthquakes 3 recurring spasmodic bursts rapid fire sequences of similar sized earthquakes with overlapping coda and occasional earthquakes with enhanced low frequency energy 4 a uniform temporal distribution of the four largest m 3 events over the first 4 months of the swarm with a cumulative seismic moment for the entire sequence through 30 september corresponding to a single m 4 earthquake 5 a b value of 1 2 and 6 submicrostrain perturbations on the nearby borehole dilatometer the first of which led the onset of swarm activity by more than 2 weeks these aspects of the swarm together with its location along the southern extension of the youthful mono inyo volcanic chain which last erupted 500 to 600 years ago point to a magmatic source for the modest but persistent influx of strain energy into the crust beneath mammoth mountain

natural and industrial analogues for leakage of co2 from storage reservoirs identification of features events and processes and lessons learned instances of gas leakage from naturally occurring co2 reservoirs and natural gas storage sites serve as analogues for the potential release of co2 from geologic storage sites this paper summarizes and compares the features events and processes that can be identified from these analogues which include both naturally occurring releases and those associated with industrial processes the following conclusions are drawn 1 carbon dioxide can accumulate beneath and be released from primary and secondary shallower reservoirs with capping units located at a wide range of depths 2 many natural releases of co2 are correlated with a specific event that triggered the release 3 unsealed fault and fracture zones may act as conduits for co2 flow from depth to the surface 4 improperly constructed or abandoned wells can rapidly release large quantities of co2 5 the types of co2 release at the surface vary widely between and within different leakage sites 6 the hazard to human health was small in most cases possibly because of implementation of post leakage public education and monitoring programs 7 while changes in groundwater chemistry were related to co2 leakage waters often remained potable lessons learned for risk assessment associated with geologic carbon sequestration are discussed

integrated thermal infrared imaging and structure from motion photogrammetry to map apparent temperature and radiant hydrothermal heat flux at mammoth mountain ca usa abstract this work presents a method to create high resolution cm scale orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area a ground based thermal infrared tir camera was used to collect 1 a set of overlapping and offset visible imagery around the study area during the daytime and 2 time series of co located visible and tir imagery at one or more sites within the study area from pre dawn to daytime daytime visible imagery was processed using the structure from motion photogrammetric method to create a digital elevation model onto which pre dawn tir imagery was orthorectified and georeferenced three dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms e g google earth arcgis we demonstrate this method at the mammoth mountain fumarole area on mammoth mountain ca time averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73 7 c and 450 w m 2 respectively while the estimated radiant hydrothermal heat emission rate from the area was 1 54 kw results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat related hazards on the volcano

modeling gravity and trilateration data in long valley california 1983 1984 during the period july 1982 through july 1984 a series of repeated high precision gravity measurements have been undertaken in and around long valley california data were collected at about 40 sites using three lacoste romberg model g gravity meters at the same time the u s geological survey was conducting a program of high precision line length measurements throughout the same area significant changes were observed with both types of data during the intervals 1982 1983 and 1983 1984 previous work by us has shown that deformation data during the interval 1975 1983 are consistent with a model for the inflation of long valley caldera which includes magma injection beneath the south central caldera at a depth of only 5 km simultaneous inversion of the trilateration and gravity data for the period 1983 1984 shows that most of the previous model is still reasonably consistent with the data and implies injected volumes of between 0 01 and 0 02 km3 additionally uplift during this period occurred along the inyo domes chain of vents and flows indicating perhaps a new source of inflation in the northwest part of the caldera this uplift amounts to a few centimeters and implies a volume increase of perhaps 0 004 km3 at reasonably shallow depth 3 km the total amount of uplift in the northwest is small in comparison to the total uplift centered on the central resurgent dome total vertical displacement well in excess of half a meter for purposes of comparison we examine several models one of which involves injection at the base of the crust this model implies much higher injected volumes as much as 0 15 0 2 km3

structural controls on the emission of magmatic carbon dioxide gas long valley caldera usa we present a degassing study of long valley caldera that explores the structural controls upon emissions of magmatic carbon dioxide gas a total of 223 soil gas samples were collected and analyzed for stable carbon isotopes using a field portable cavity ring down spectrometer this novel technique is flexible accurate and provides sampling feedback on a daily basis sampling sites included major and minor volcanic centers regional throughgoing faults caldera related structures zones of elevated seismicity and zones of past and present hydrothermal activity the classification of soil gases based on their 13c and co2 values reveals a mixing relationship among three end members atmospheric biogenic and magmatic signatures dominated by biogenic contributions 4 vol 24 are found on the caldera floor the interior of the resurgent dome and areas associated with the hilton creek and hartley springs fault systems with the introduction of the magmatic component 100 vol 4 5 samples acquire mixing and hydrothermal signatures and are spatially associated with the central caldera and mammoth mountain in particular they are concentrated along the southern margin of the resurgent dome where the interplay between resurgence related reverse faulting and a bend in the regional fault system has created a highly permeable fracture network suitable for the formation of shallow hydrothermal systems this contrasts with the south moat where despite elevated seismicity a thick sedimentary cover has formed an impermeable cap inhibiting the ascent of fluids and gases to the surface

geochemical monitoring for potential environmental impacts of geologic sequestration of co2 carbon dioxide sequestration is now considered an important component of the portfolio of options for reducing greenhouse gas emissions to stabilize their atmospheric levels at values that would limit global temperature increases to the target of 2 c by the end of the century pacala and socolow 2004 ipcc 2005 2007 benson and cook 2005 benson and cole 2008 iea 2012 romanak et al 2013 increased anthropogenic emissions of co2 have raised its atmospheric concentrations from about 280 ppmv during pre industrial times to 400 ppmv today and based on several defined scenarios co2 concentrations are projected to increase to values as high as 1100 ppmv by 2100 white et al 2003 ipcc 2005 2007 eia 2012 global ccs institute 2012 an atmospheric co2 concentration of 450 ppmv is generally the accepted level that is needed to limit global temperature increases to the target of 2 c by the end of the century this temperature limit likely would moderate the adverse effects related to climate change that could include sea level rise from the melting of alpine glaciers and continental ice sheets and from the ocean warming increased frequency and intensity of wildfires floods droughts and tropical storms and changes in the amount timing and distribution of rain snow and runoff ipcc 2007 sundquist et al 2009 iea 2012 rising atmospheric co2 concentrations are also increasing the amount of co2 dissolved in ocean water lowering its ph from 8 1 to 8 0 with potentially disruptive effects on coral reefs plankton and marine ecosystems adams and caldeira 2008 schrag 2009 sundquist et al 2009 sedimentary basins in general and deep saline aquifers in particular are being investigated as possible repositories for the large volumes of

the interpretation of gravity changes and crustal deformation in active volcanic areas simple models like the well known point source of dilation mogi s source in an elastic homogeneous and isotropic half space are widely used to interpret geodetic and gravity data in active volcanic areas this approach appears at odds with the real geology of volcanic regions since the crust is not a homogeneous medium and magma chambers are not spheres in this paper we evaluate several more realistic source models that take into account the influence of self gravitation effects vertical discontinuities in the earth s density and elastic parameters and non spherical source geometries our results indicate that self gravitation effects are second order over the distance and time scales normally associated with volcano monitoring for an elastic model appropriate to long valley caldera we find only minor differences between modeling the 1982 1999 caldera unrest using a point source in elastic homogeneous half spaces or in elasto gravitational layered half spaces a simple experiment of matching deformation and gravity data from an ellipsoidal source using a spherical source shows that the standard approach of fitting a center of dilation to gravity and uplift data only excluding the horizontal displacements may yield estimates of the source parameters that are not reliable the spherical source successfully fits the uplift and gravity changes overestimating the depth and density of the intrusion but is not able to fit the radial displacements

volcano tectonic earthquakes a new tool for estimating intrusive volumes and forecasting eruptions abstract we present data on 136 high frequency earthquakes and swarms termed volcano tectonic vt seismicity which preceded 111 eruptions at 83 volcanoes plus data on vt swarms that preceded intrusions at 21 other volcanoes we find that vt seismicity is usually the earliest reported seismic precursor for eruptions at volcanoes that have been dormant for decades or more and precedes eruptions of all magma types from basaltic to rhyolitic and all explosivities from vei 0 to ultraplinian vei 6 at such previously long dormant volcanoes because large eruptions occur most commonly during resumption of activity at long dormant volcanoes vt seismicity is an important precursor for the earth s most dangerous eruptions vt seismicity precedes all explosive eruptions of vei 5 and most if not all vei 4 eruptions in our data set surprisingly we find that the vt seismicity originates at distal locations on tectonic fault structures at distances of one or two to tens of kilometers laterally from the site of the eventual eruption and rarely if ever starts beneath the eruption site itself the distal vt swarms generally occur at depths almost equal to the horizontal distance of the swarm from the summit out to about 15 km distance beyond which hypocenter depths level out we summarize several important characteristics of this distal vt seismicity including swarm like nature onset days to years prior to the beginning of magmatic eruptions peaking of activity at the time of the initial eruption whether phreatic or magmatic and large non double couple component to focal mechanisms most importantly we show that the intruded magma volume can be simply estimated from the cumulative seismic moment of the vt seismicity from log10 v 0 77 log moment 5 32 with volume v in cubic meters and seismic moment in newton meters because the cumulative seismic moment can be approximated from the size of just the few largest events and is quite insensitive to precise locations the intruded magma volume can be quickly and easily estimated with few short period seismic stations notable cases in which distal vt events preceded eruptions at long dormant volcanoes include nevado del ruiz 1984 1985 pinatubo 1991 unzen 1989 1995 soufriere hills 1995 shishaldin 1989 1999 tacana 1985 1986 pacaya 1980 1984 rabaul 1994 and cotopaxi 2001 additional cases are recognized at frequently active volcanoes including popocateptl 2001 2003 and mauna loa 1984 we present four case studies pinatubo soufriere hills unzen and tacana in which we demonstrate the above mentioned vt characteristics prior to eruptions using regional data recorded by neic we recognized in near real time that a huge distal vt swarm was occurring deduced that a proportionately huge magmatic intrusion was taking place beneath the long dormant sulu range new britain island papua new guinea that it was likely to lead to eruptive activity and warned rabaul volcano observatory days before a phreatic eruption occurred this confirms the value of this technique for eruption forecasting we also present a counter example where we deduced that a vt swarm at volcan cosiguina nicaragua indicated a small intrusion insufficient to reach the surface and erupt finally we discuss limitations of the method and propose a mechanism by which this distal vt seismicity is triggered by magmatic intrusion

inverse modelling of seawater intrusion in the llobregat delta deep aquifer abstract a flow and mass transport mathematical model has been calibrated to simulate piezometric head and chloride evolution in the llobregat delta confined aquifer a twenty year period 1965 1985 is simulated with monthly time steps automatic estimation of flow and transport parameters are obtained by means of a code that simulates flow and mass transport of constant density fluids in this case density differences owing to groundwater salinity changes by marine intrusion can be neglected because the aquifer thickness is relatively small and because both the horizontal density gradient and the aquifer dip are small calibration of the flow problem leads to an excellent fit between measured and computed heads which however can be obtained with different transmissivity patterns when switching to the transport problem best results in terms of concentration fits are obtained by associating the seawater intrusion plumes with high transmissivity zones that can be attributed to palaeochannels in short transient head and concentration data have been used jointly for automatic calibration of a regional model which has proven advantageous both because it facilitates model selection and because it has led to a model with an improved conceptual basis

a definitive approach to turbulence statistical studies in planetary boundary layers abstract a method for comprehensive statistical data analysis is presented it includes a procedure for selection of segments within a data record where data can be considered stationary allowing the computation of statistical parameters from data over selected segments and their confidence intervals estimating the statistical reliability of the parameters the method is illustrated by analysing the vertical component of the wind velocity data collected by research aircraft flights over lake michigan during project less lake effect snow studies the results indicate that for skewness and kurtosis the requirements for acceptable averaging distances are less limiting than the required distances for corresponding third and forth order moments

diffuse gas emissions at the ukinrek maars alaska implications for magmatic degassing and volcanic monitoring abstract diffuse co 2 efflux near the ukinrek maars two small volcanic craters that formed in 1977 in a remote part of the alaska peninsula was investigated using accumulation chamber measurements high co 2 efflux in many places exceeding 1000 g m 2 d 1 was found in conspicuous zones of plant damage or kill that cover 30 000 50 000 m 2 in area total diffuse co 2 emission was estimated at 21 44 t d 1 gas vents 3 km away at the gas rocks produce 0 5 t d 1 of co 2 that probably derives from the ukinrek maars basalt based on similar 13 c values 6 3 he 4 he ratios 5 9 7 2 r a and co 2 3 he ratios 1 2 10 9 in the two areas a lower 3 he 4 he ratio 2 7 r a and much higher co 2 3 he ratio 9 10 10 in gas from the nearest arc front volcanic center mount peulik ugashik provide a useful comparison the large diffuse co 2 emission at ukinrek has important implications for magmatic degassing subsurface gas transport and local toxicity hazards gas water rock interactions play a major role in the location magnitude and chemistry of the emissions

high resolution imaging of hydrothermal heat flux using optical and thermal structure from motion photogrammetry abstract quantifying hydrothermal heat flux at meter scale resolution over 0 25 km2 is required to bridge in situ heat flux and satellite based measurements we advance a methodology that blends ground based daytime optical and nighttime thermal infrared tir imagery using structure from motion photogrammetry to map radiant hydrothermal heat flux over these scales at sites with low signal to noise ratios that would otherwise be difficult to characterize using for example unmanned aerial systems the improved method uses a computerized telescopic mount to relocate and align daytime optical acquisitions with nighttime tir imagery thereby enabling tir acquisition from multiple camera orientations positioned throughout a study area this facilitates mapping of thermal features at sites of varying size and complexity and helps to ameliorate topographic occlusion effects and geometric distortions that can bias radiant hydrothermal heat flux estimates derived from the resulting orthorectified thermal maps we assessed detection thresholds of this method at three sites across central california which range in size topography and heat flux conditions we found that blending of optical and thermal acquisitions successfully detected anomalous heat flux even in cases where temperatures were only slightly greater than background this approach might be applied to a variety of volcanic and hydrothermal systems to quantify the spatial distribution of heat flux and how this may relate to factors such as the distribution of ground fractures and lava flow rheology

influence of magmatic hydrothermal activity on brine evolution in closed basins searles lake california evaporites in a 700 m long core km 3 from searles lake california preserve a record of the chemical evolution of inflow waters chemical analyses of fluid inclusions in halite and evaporite minerals show that the major ion composition of inflow waters to searles lake was changed by distant hydrothermal activity associated with magmatism at long valley caldera between 1 27 and 1 0 m y ago below core depths of 291 m the evaporites consist of ca bearing sulfates anhydrite glauberite and halite fluid inclusions in the halite show that parent waters were na cl so42 rich waters above 291 m the evaporites include sodium carbonates pirssonite trona and halite and fluid inclusion brines are na k hco3 co32 cl so42 rich these fluctuations in mineralogy and brine chemistry document an alkalinity spike beginning between 1 27 and 1 0 ma when inflow waters to searles lake crossed the caco3 chemical divide and began to produce alkaline brines that precipitated trona upon evaporation the owens river is a modern chemical analog for inflow water into searles lake beginning between 1 27 ma and 1 0 ma a major contributor of solutes to the owens river is hot creek in long valley caldera which is fed by hydrothermal springs with high alkalinity from magmatically derived co2 the timing of magmatism in owens valley and the appearance of sodium carbonate minerals in core km 3 suggest a causal relationship volcanism and hydrothermal activity provided co2 and elevated alkalinity to searles lake inflow waters 0 5 0 2 m y before the eruptions that formed the bishop tuff and long valley caldera

multiscale insar time series mints analysis of surface deformation 1 we present a new approach to extracting spatially and temporally continuous ground deformation fields from interferometric synthetic aperture radar insar data we focus on unwrapped interferograms from a single viewing geometry estimating ground deformation along the line of sight our approach is based on a wavelet decomposition in space and a general parametrization in time we refer to this approach as mints multiscale insar time series the wavelet decomposition efficiently deals with commonly seen spatial covariances in repeat pass insar measurements since the coefficients of the wavelets are essentially spatially uncorrelated our time dependent parametrization is capable of capturing both recognized and unrecognized processes and is not arbitrarily tied to the times of the sar acquisitions we estimate deformation in the wavelet domain using a cross validated regularized least squares inversion we include a model resolution based regularization in order to more heavily damp the model during periods of sparse sar acquisitions compared to during times of dense acquisitions to illustrate the application of mints we consider a catalog of 92 ers and envisat interferograms spanning 16 years in the long valley caldera ca region mints analysis captures the ground deformation with high spatial density over the long valley region

deformation near the casa diablo geothermal well field and related processes long valley caldera eastern california 1993 2000 abstract regional first order leveling lines which extend from lee vining ca to tom s place ca have been surveyed periodically since 1957 by the u s geological survey usgs the national geodetic survey ngs and caltrans two of the regional survey lines or leveling networks intersect at the casa diablo geothermal well field these leveling networks referenced to a distant bench mark c916 near lee vining provide time series vertical control data of land surface deformation that began around 1980 these data are also useful for delineating localized subsidence at casa diablo related to reservoir pressure and temperature changes owing to geothermal development that began in 1985 a comparison of differences in bench mark elevations for five time periods between 1983 and 1997 shows the development and expansion of a subsidence bowl at casa diablo the subsidence coincides spatially with the geothermal well field and temporally with the increased production rates and the deepening of injection wells in 1991 which resulted in an increase in the rate of pressure decline the subsidence superimposed on a broad area of uplift totaled about 310 mm by 1997 the usgs established orthogonal tilt arrays in 1983 to better monitor deformation across the caldera one tilt array dbr was established near what would later become the casa diablo geothermal well field this array responded to magmatic intrusions prior to geothermal development tilting away from the well field with the start of geothermal fluid extraction in 1985 tilt at the dbr array reversed direction and began tilting into the well field in 1991 geothermal power production was increased by a factor of four and reservoir pressures began a period of steep decline these changes caused a temporary three fold increase in the tilt rate the tilt rate became stable in 1993 and was about 40 lower than that measured in 1991 1992 but still greater than the rates measured during 1985 1990 data from the local leveling networks spanning the well field and the bounding graben were analyzed for several 2 year periods 1993 1995 1995 1997 and 1997 1999 annual rates of change across the normal faults bounding the graben have steadily decreased for each 2 year period between 1993 and 1999 reflecting the slowing decline in geothermal reservoir pressure horizontal control data from a two color electronic distance meter edm defined the lateral extent of subsidence at casa diablo the edm and leveling data elucidate the localized effect of the shallow source of subsidence and the broader effect of the deeper magmatic inflation source data from bench marks common to both the vertical and the horizontal control networks were used to assess the effect of subsidence on the edm base station casa modeling of geodetic data collected during periods of little or no magmatic inflation indicated that the casa two color edm station is being drawn toward the well field at a rate of 3 5 mm yr

crustal structure beneath long valley caldera from modeling of teleseismic p wave polarizations and ps converted waves in this study the authors present new constraints on the nature of the low velocity zone beneath long valley caldera based on the measured propagation directions of teleseismic p waves and on modeling of p to s converted waves the low velocity body is a large asymmetrical volume which deepens to the east extending from depths of 7 to 30 km it contains lower velocities than originally proposed by earlier teleseismic studies in particular there is a tabular feature between 7 and 11 km depth that has a reduction in velocity of about 30 these low velocities imply a much greater percentage of melt in the crust beneath long valley caldera than previously estimated array analysis of large delayed arrivals identifies them to be ps converted waves from the shoulders and roof of this tabular zone these conversions bound the depth to the magma chamber roof to be within about 10 km of the surface these results are consistent with elements from several other studies and the authors present an integrated and improved model of crustal structure at long valley the concordance of the deeper low velocity zones with regional structural trends implies that the shallow low velocity feature is a cupola on topmore of an asymmetric diapiric ridge rising up from the migmatized lower crust of the basin and range the authors present two contrasting interpretations of the geometry of low velocity zones in the crust one implies a time invariant magma chamber and conduit system for long valley caldera the other implies an evolution of that system from a simple vertical regime to its current asymmetrical geometry 37 refs 19 figs 1 tab less

principal component analysis of geodetically measured deformation in long valley caldera eastern california 1983 1987 typical geodetic measurements of deformation consist of repeated surveys of a particular geodetic network such deformation data can be interpreted as a consequence of one or more self coherent sources by means of principal component analysis a self coherent source is defined as any source that produces deformation that is time and space separable principal component analysis then gives the time and space factors that characterize the deformation attributed to each self coherent source geodetic measurements of deformation at long valley caldera provide two examples of the application of principal component analysis a 40 line trilateration network surrounding the caldera was surveyed in midsummer 1983 1984 1985 1986 and 1987 principal component analysis indicates that the observed deformation can be represented by a single coherent source the time dependence for that source displays a rapid rate of deformation in 1983 1984 followed by less rapid but uniform rate in the 1984 1987 interval the spatial factor seems consistent with expansion of a magma chamber beneath the caldera plus some shallow right lateral slip on a vertical fault in the south moat of the caldera an independent principal component analysis of the 1982 1983 1984 1985 1986 and 1987 leveling across the caldera requires two self coherent sources to explain the deformation the deformation pattern produced by the larger of these two sources appears to be roughly consistent with that found from the trilateration data the deformation due to the second source is a nearly uniform tilt in the uplift profile presumably that tilt is simply an artifact of systematic error in the leveling

elevated carbon dioxide flux at the dixie valley geothermal field nevada relations between surface phenomena and the geothermal reservoir abstract in the later part of the 1990s a large die off of desert shrubs occurred over an approximately 1 km 2 area in the northwestern section of the dixie valley dv geothermal field this paper reports results from accumulation chamber measurements of soil co 2 flux from locations in the dead zone and stable isotope and chemical data on fluids from fumaroles shallow wells and geothermal production wells within and adjacent to the dead zone a cumulative probability plot shows three types of flux sites within the dead zone locations with a normal background co 2 flux 7 g m 2 day 1 moderate flux sites displaying excess geothermal flux and high flux sites near young vents and fumaroles a maximum co 2 flux of 570 g m 2 day 1 was measured at a location adjacent to a fumarole using statistical methods appropriate for lognormally distributed populations of data estimates of the geothermal flux range from 7 5 t day 1 from a 0 14 km 2 site near the stillwater fault to 0 1 t day 1 from a 0 01 km 2 location of steaming ground on the valley floor anomalous co 2 flux is positively correlated with shallow temperature anomalies the anomalous flux associated with the entire dead zone area declined about 35 over a 6 month period the decline was most notable at a hot zone located on an alluvial fan and in the sg located on the valley floor gas geochemistry indicates that older established fumaroles along the stillwater fault and a 2 year old vent in the lower section of the dead zone discharge a mixture of geothermal gases and air or gases from air saturated meteoric water asmw stable isotope data indicate that steam from the smaller fumaroles is produced by 100 c boiling of these mixed fluids and reservoir fluid steam from the senator fumarole sf and from shallow wells penetrating the dead zone are probably derived by 140 c to 160 c boiling of reservoir fluid carbon 13 isotope data suggest that the reservoir co 2 is produced mainly by thermal decarbonation of hydrothermal calcite in veins that cut reservoir rocks formation of the dead zone is linked to the reservoir pressure decline caused by continuous reservoir drawdown from 1986 to present these reservoir changes have restricted flow and induced boiling in a subsurface hydrothermal outflow plume extending from the stillwater fault southeast toward the dv floor we estimate that maximum co 2 flux in the upflow zone along the stillwater fault in 1998 was roughly seven to eight times greater than the pre production flux in 1986 the eventual decline in co 2 flux reflects the drying out of the outflow plume

sources and fractionation processes influencing the isotopic distribution of h o and c in the long valley hydrothermal system california u s a abstract the isotopic ratios of h o and c in water within the long valley caldera california reflect input from sources external to the hydrothermal reservoir a decrease in d in precipitation of 0 5 km 1 from west to east across long valley is caused by the introduction of less fractionated marine moisture through a low elevation embayment in the sierra nevada mountain range relative to seasonal fluctuations in precipitation 158 to 35 d ranges in hot and cold surface and groundwaters are much less variable 135 to 105 only winter and spring moisture reflecting higher precipitation rates with lighter isotopic signatures recharge the hydrological system the hydrothermal fluids are mixtures of isotopically heavy recharge d 115 18 o 15 derived from the mammoth embayment and isotopically lighter cold water d 135 18 o 18 this cold water is not representative of current local recharge the 13 c values for dissolved carbon in hot water are significantly heavier 7 to 3 than in cold water 18 to 10 denoting a separate hydrothermal origin these 13 c values overlie the range generally attributed to magmatic degassing of co 2 however 13 c values of metamorphosed paleozoic basement carbonates surrounding long valley fall in a similar range indicating that hydrothermal decarbonization reactions are a probable source of co 2 the 13 c and 18 o values of secondary travertime and vein calcite indicate respective fractionation with co 2 and h 2 o at temperatures approximating current hydrothermal conditions

shallow and peripheral volcanic sources of inflation revealed by modeling two color geodimeter and leveling data from long valley caldera california 1988 1992 we refined the model for inflation of the long valley caldera near mammoth lakes california by combining both geodetic measurements of baseline length and elevation changes baseline length changes measured using a two color geodimeter with submillimeter precision revealed that the resurgent dome started to reinflate in late 1989 measurements between late 1989 and mid 1992 revealed nearly 13 cm of extension across the resurgent dome geodetic leveling surveys with approximately 2 mm precision made in late 1988 and in mid 1992 revealed a maximum of about 8 cm of uplift of the resurgent dome two ellipsoidal sources satisfy both the leveling and two color measurements whereas spherical point sources could not the model s primary inflation source is located 5 5 km beneath the resurgent dome with the two horizontal axes being nearly equal in size and the vertical axis being 4 times the length of the horizontal axes a second ellipsoidal source was added to improve the fit to the two color measurements this secondary source is located at a depth between 10 and 20 km beneath the south moat of the caldera and has the geometry of an elongated ellipsoid or pipe that dips down to the northeast in addition the leveling data suggest dike intrusion beneath mammoth mountain during the 1988 1992 interval which is likely associated with an intense swarm of small earthquakes during the summer of 1989 at that location our analysis shows the dike intrusion to be the shallowest of the three sources with a depth range of 1 3 km below the surface to the top of the intrusion

co2 discharge in an active non volcanic continental rift area czech republic characterisation δ13c 3he 4he and quantification of diffuse and vent co2 emissions abstract in the western eger rift er area along the pocatky plesna fault zone ppz co 2 degassing occurs predominantly within two mofette fields bublak and hartousov we studied 27 wet mofettes belonging to these mofette fields for gas emission rates repeatedly between 2007 and 2009 and selected mofettes for gas composition and isotope ratios 13 c 3 he 4 he detailed ground mapping along the ppz provided further two separated diffuse degassing structures dds within the mofette fields hartousov and bublak the dds hartousov was studied in detail by measurements of 682 co 2 soil gas concentrations 762 co 2 soil gas fluxes max 10 grid spacing and partly by analyses of isotope ratios 13 c 12 c 3 he 4 he of soil gas at the dds hartousov the total co 2 soil flux yielded 1 559 t m 2 d 1 in spring 2009 and the co 2 emission rate at the wet mofettes of hartousov mofette field yielded 0 62 t d 1 the total co 2 discharge of the 27 wet mofettes was 3 75 t d 1 at sites with high co 2 soil flux the portion of mantle derived helium is in the same range as the releasing at wet mofettes both cover the signature of the subcontinental mantle also the 13 c values analysed in the gas releasing from wet mofettes and those analysed in soil gas are nearly the same taking in account a biogenic soil co 2 flux of 25 g m 2 d 1 as background the mantle derived co 2 flux yielded approximately 1566 t m 2 d 1 as a result of the co 2 flux mapping of the dds hartousov it could be proved that 97 4 of the released soil co 2 1 518 t m 2 d 1 stems from sites with co 2 fluxes higher than 500 g m 2 d 1 pointing to dominantly fault related co 2 release at the central mofette bublak b2 the gas emission rate was determined for the first time in 1993 measurements repeated between 2007 and 2009 showed a clear increase in the gas emission rate of more than 40 correlating well with the increase of the 3 he 4 he ratios from 5 ra to approximately 6 ra between 1993 and 2008 at this location brauer et al 2009 the bublak mofette field is characterised by the highest co 2 emission rate along the ppz and in combination with the helium isotope signature of the european subcontinental mantle this area was identified as a deep reaching fluid injection zone

acoustic waves generated by gusty flow over hilly terrain 1 we examine the generation of acoustic waves by gusty flow over hilly terrain we use simple theoretical models of the interaction between terrain and eddies and a linear model of acoustic gravity wave propagation the calculations presented here suggest that over a dense array of geographically extensive sources orographically generated vertically propagating acoustic waves can be a significant cause of thermospheric heating this heating may account in good part for the thermospheric hot spot near the andes reported by meriwether et al 1996 1997

reinvestigation of the 1989 mammoth mountain california seismic swarm and dike intrusion abstract during the period of unrest and inflation beneath long valley east central california between 1988 and 1992 a swarm of seismic activity occurred beneath mammoth mountain on the caldera rim in 1989 followed by the onset of diffuse co 2 degassing these events combined with elevation changes along a leveling line north of mammoth mountain suggested a dike intrusion an early inversion of deformation data resulted in a dike model with an unrealistically small amount of opening 13 cm for the proposed dimensions the current reinvestigation of the 1989 seismic event at mammoth mountain ca incorporates relocated earthquakes prejean et al 2003 and ellipsoidal inflation sources beneath the caldera to the east langbein 2003 to better constrain the location and dimensions of a proposed dike intrusion beneath mammoth mountain assuming that the dike coincides with a keel of seismicity at 7 9 km depth most of the dislocation parameters can be constrained fixing all dike parameters except opening to coincide with the keel inversion of the local leveling data yields a dike with 3 3 m of opening allowing the dike height to vary as well improves the fit to the data significantly and results in a dike 1 m wide and nearly 7 m high these results indicate that the intruded dike had significantly more opening than previously modeled magma volumes for reasonable models center around 0 015 km 3 suggesting a small likely basaltic intrusion

permeability changes during remediation of an aquifer affected by sea water intrusion a laboratory column study summary during flushing of a seawater affected aquifer with freshwater fine particles can be mobilized and can subsequently clog up pores thereby causing a reduction of permeability here we used packed columns 25 cm length to experimentally investigate the changes in permeability during such a remediation scenario we hypothesized that a gradual and abrupt change in salinity as well as the pressure boundary conditions along the column will affect the particle release and permeability changes we collected sediments from a coastal aquifer in china in which seawater had intruded the sediments were packed into laboratory columns the columns were oriented horizontally and instrumented with a series of piezometers to measure hydraulic heads along the column several sequences of displacements of seawater electrical conductivity ec 48 5 ms cm with freshwater ec 0 78 ms cm were passed through the columns permeability was determined from measured flow rates and hydraulic heads experiments were conducted both with constant head as well as with constant flux conditions column outflow was analyzed for suspended particles and electrical conductivity the results indicate that the permeability was reduced by up to 70 when seawater was displaced with freshwater under constant head conditions permeability reductions were more pronounced than under constant flux the critical salinity i e electrical conductivity associated with the critical salt concentration for particle release in the sediments was 7 ms cm when salinity was changed abruptly fine particles were eluted from the column however when the salinity change was gradual no fines were eluted in agreement with previous literature data we observed a more pronounced reduction of permeability under an abrupt than under a gradual salinity change permeability reduction was not uniform along the column with generally decreasing permeability with increasing distance from the column inlet

permeability decrease in sandstone reservoirs by fluid injection hydrodynamic and chemical effects abstract formation damage induced by a chemical effect resulting from non compatibility between the injected fluid and the reservoir has been studied extensively and is well documented however formation damage induced by a hydrodynamic effect of flow and the combined effects when the salinity and flow rate are varied simultaneously have been studied less this paper describes results from a set of core flood experiments carried out with a variety of filtered nacl solutions subjected to increased flow rates to investigate the mechanisms of formation damage induced by the release and capture of in situ particles regarding the release mechanisms the results confirm the existence of a critical flow rate above which the permeability decreases as a consequence of the hydrodynamic release of particles this critical flow rate is found to be higher than those observed in the literature and is observed to increase with the fluid salinity as predicted by the electric double layer theory the higher the salinity of the fluid the higher is the critical flow rate and the less is the permeability decrease regarding the capture mechanisms filtering or size exclusion appears to be the principal cause of permeability decrease at high injection flow rates the hydrodynamic effect can reduce the permeability by more than 50 but is less severe than the chemical effect

helium isotope and gas discharge variations associated with crustal unrest in long valley caldera california 1989 1992 the onset of anomalous seismic activity in 1989 beneath mammoth mountain on the southwestern rim of the long valley caldera california was followed within approximately 4 months by a large increase in sup 3 he sup 4 he in vapor discharged from a fumarole on the north side of the mountain the helium isotopic ratio at this vent rose to a maximum of 6 7 r sub a in july 1990 and subsequently declined to values near 5 r sub a potential sources of the sup 3 he rich vapors include degassing of fresh magma degassing from fresh surfaces generated in newly fractured igneous rocks and volatile release from a sup 3 he rich gas chamber situated above previously emplaced intrusives the magnitude of the increase in helium isotopic composition from 3 8 to 6 7 r sub a the persistence of relatively high values 5 r sub a over a period of 3 years the increase in the flux of total he relative to gases in air saturated water and the increases in the rates of discharge of steam and gas from this fumarole indicate that magmatic intrusion did in fact begin in 1989 beneath mammoth mountain seismic activity and limited measurements of extensional deformation at the surface suggest that the depth of intrusion maymore be as shallow as 2 km consistent with the prompt appearance of increased sup 3 he sup 4 he ratios in the fumarolic gas and that the intrusive process may have persisted for approximately 1 year in contrast a similar combination of magmatic intrusion and anomalous seismic activity beneath the resurgent dome south moat region during the 1989 1991 period resulted in at most relatively small changes in sup 3 he sup 4 he in fumarolic discharge at the southern edge of the resurgent dome the more subdued response may result from a combination of greater intrusive depths and greater dilution of sup 3 he rich inputs to thermal fluid reservoirs in the shallow hydrothermal system in this area compared with mammoth mountain 60 refs 11 figs 4 tabs less

inferences on the hydrothermal system beneath the resurgent dome in long valley caldera east central california usa from recent pumping tests and geochemical sampling abstract quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the long valley caldera including the present day hydrothermal system which has been active over the past 40 kyr the most recent period of crustal unrest in this region of east central california began around 1980 and has included periods of intense seismicity and ground deformation uplift totaling more than 0 7 m has been centered on the caldera s resurgent dome and is best modeled by a near vertical ellipsoidal source centered at depths of 6 7 km modeling of both deformation and microgravity data now suggests that 1 there are two inflation sources beneath the caldera a shallower source 7 10 km beneath the resurgent dome and a deeper source 15 km beneath the caldera s south moat and 2 the shallower source may contain components of magmatic brine and gas the long valley exploration well lvew completed in 1998 on the resurgent dome penetrates to a depth of 3 km directly above this shallower source but bottoms in a zone of 100 c fluid with zero vertical thermal gradient although these results preclude extrapolations of temperatures at depths below 3 km other information obtained from flow tests and fluid sampling at this well indicates the presence of magmatic volatiles and fault related permeability within the metamorphic basement rocks underlying the volcanic fill in this paper we present recently acquired data from lvew and compare them with information from other drill holes and thermal springs in long valley to delineate the likely flow paths and fluid system properties under the resurgent dome additional information from mineralogical assemblages in core obtained from fracture zones in lvew documents a previous period of more vigorous and energetic fluid circulation beneath the resurgent dome although this system apparently died off as a result of mineral deposition and cooling and or deepening of magmatic heat sources flow testing and tidal analyses of lvew water level data show that relatively high permeability and strain sensitivity still exist in the steeply dipping principal fracture zone penetrated at a depth of 2 6 km the hydraulic properties of this zone would allow a pressure change induced at distances of several kilometers below the well to be observable within a matter of days this indicates that continuous fluid pressure monitoring in the well could provide direct evidence of future intrusions of magma or high temperature fluids at depths of 5 7 km

effects of geothermal development on deformation in the long valley caldera eastern california 1985 1994 long valley caldera in east central california has been the site of crustal unrest in the form of seismicity and ground deformation in response to magmatic inflation since 1980 uplift of the resurgent dome has totaled 0 6 m over the 1975 1992 period within this region of uplift and near the southwestern edge of the resurgent dome is the casa diablo area which experienced relative subsidence of 0 17 m between 1985 and 1992 geothermal fluid production began at casa diablo in 1985 to supply a binary electric power plant currently three such plants generate a total of about 40 mw of electricity the plants are supplied by 170 c water pumped from depths near 150m all the produced water is reinjected at cooler temperatures at depths near 600 m analyses of data from 1 regional leveling lines and a network of bench marks in the geothermal well field area 2 tilt observations from an l shaped array of bench marks and 3 calculations relating pressure and temperature changes to subsidence indicate that relative subsidence at casa diablo results mainly from reductions in pressure in the shallow production reservoir and overlying formations and reductions in temperature in the underlying injection reservoir secondary effects on deformation are caused by offsets along the taylor bryant fault bounding the west side of the well field

modeling of stress changes at mayon volcano philippines in this paper we analyze the stress change associated with the inverted volcanic source models at mayon volcano philippines where there are gravity changes without significant deformation after the 1993 eruption we detail the applicable data and the associated inversion techniques and models prior to calculating the appropriate stress changes it is determined that the stress change associated with the central magmatic source produces compressional stress changes at a secondary source to the northwest prompting a change in the local water storage in the underlying fractured rock

the mechanics of unrest at long valley caldera california 1 modeling the geometry of the source using gps leveling and two color edm data we surveyed 44 existing leveling monuments in long valley caldera in july 1999 using dual frequency global positioning system gps receivers we have been able to tie gps and leveling to a common reference frame in the long valley area and computed the vertical deformation by differencing gps based and leveled orthometric heights the resurgent dome uplifted 74 7 cm from 1975 to 1999 to define the inflation source we invert two color edm and uplift data from the 1985 1999 unrest period using spherical or ellipsoidal sources we find that the ellipsoidal source satisfies both the vertical and horizontal deformation data whereas the spherical point source cannot according to our analysis of the 1985 1999 data the main source of deformation is a prolate ellipsoid located beneath the resurgent dome at a depth of 5 9 km 95 bounds of 4 9 7 5 km this body is vertically elongated has an aspect ratio of 0 475 95 bounds are 0 25 0 65 and a volume change of 0 086 km3 95 bounds are 0 06 0 13 km3 failure to account for the ellipsoidal nature of the source biases the estimated source depth by 2 1 km 35 and the source volume by 0 038 km3 44

soil efflux and total emission rates of magmatic co2 at the horseshoe lake tree kill mammoth mountain california 1995 1999 abstract we report the results of eight soil co 2 efflux surveys by the closed circulation chamber method at the horseshoe lake tree kill hltk the largest tree kill on mammoth mountain the surveys were undertaken from 1995 to 1999 to constrain total hltk co 2 emissions and to evaluate occasional efflux surveys as a surveillance tool for the tree kills hltk effluxes range from 1 to 10 000 g m 2 day 1 grams co 2 per square meter per day they are not normally distributed station efflux rates can vary by 7 35 during the course of the 8 to 16 h surveys disturbance of the upper 2 cm of ground surface causes effluxes to almost double semivariograms of efflux spatial covariance fit exponential or spherical models they lack nugget effects efflux contour maps and total co 2 emission rates based on exponential spherical and linear kriging models of survey data are nearly identical similar results are also obtained with triangulation models suggesting that the kriging models are not seriously distorted by the lack of normal efflux distributions in addition model estimates of total co 2 emission rates are relatively insensitive to the measurement precision of the efflux rates and to the efflux value used to separate magmatic from forest soil sources of co 2 surveys since 1997 indicate that contrary to earlier speculations a termination of elevated co 2 emissions at the hltk is unlikely anytime soon the hltk co 2 efflux anomaly fluctuated greatly in size and intensity throughout the 1995 1999 surveys but maintained a n s elongation presumably reflecting fault control of co 2 transport from depth total co 2 emission rates also fluctuated greatly ranging from 46 to 136 t day 1 metric tons co 2 per day and averaging 93 t day 1 the large inter survey variations are caused primarily by external meteorological processes operating on time scales of hours to days the externally caused variations can mask significant changes occurring at depth a striking example is the masking of a degassing event generated at depth and detected by a soil gas sensor network in september 1997 while an efflux survey was in progress thus occasional efflux surveys are not an altogether effective surveillance tool for the hltk and making them effective by greatly increasing their frequency may not be practical

large eddy simulation of turbulent flow in a marine convective boundary layer with snow abstract a large eddy simulation les model with ice phase included has been used to study the marine convective boundary layer filled with snow extensions to moeng s les model include the diagnosis of cloud ice mixing ratio snow precipitation and the parameterization of detailed microphysical processes model simulations are compared with cold air outbreak field observations over lake michigan as well as with the liquid phase les results for the same atmospheric conditions the buoyancy flux and vertical velocity variance profiles generated by the ice phase les are found to be more consistent with the observations than those generated by the liquid phase les results the incorporation of the ice phase into the les model has also improved the agreement of vertical velocity skewness sw between observations and les model results it has also been found that the presence of precipitation and the associated microphysical processes has a significant effect on the structure of the convective boundary

transient pore pressure response to confining stress excursions in berea sandstone flooded with an aqueous solution of co2 we measured the pore pressure response due to carbon dioxide co2 gas bubble nucleation and growth in a berea sandstone core flooded with an initially subsaturated aqueous solution of co2 in response to a rapid drop in confining stress under conditions representative of a confined aquifer a portion of the co2 in the earth s crust derived from volcanic magmatic and biogenic sources dissolves in groundwater sudden reductions in confining stress in the earth s crust occur due to dilational strain generated by the propagation of seismic rayleigh and p waves or aseismic slip in the near field of earthquakes a drop in confining stress produces a proportional drop in pore fluid pressure when the pore fluid contains dissolved co2 the pore pressure responds to a drop in confining stress like it does in the dissolved gas free case until the pore pressure falls below the bubble pressure gas bubble nucleation and diffusive growth in the pore space trigger spontaneous transient buildup of the pore fluid pressure and reduction of effective stress we measured the rate of pore fluid pressure buildup in the 100 s immediately following the confining stress drop as a function of the saturation with respect to co2 at the lowest pore pressure realized during the confining stress drop using five different co2 partial pressures the rate scales with the saturation with respect to dissolved co2 from 10 kpa min at 1 25 to 166 kpa min at 1 8 the net pore pressure rise was as large as 0 7 mpa 100 psi over 5 h

a prognostic turbulence scheme for the nonhydrostatic plume model atham the presented turbulence scheme was developed for the active tracer high resolution atmospheric model atham to parameterize the effect of subgrid scale turbulence in contrast to the commonly used assumption of local isotropy in high resolution atmospheric modeling this scheme differentiates between horizontal and vertical turbulent exchange to represent the strong influence of buoyancy forces and vertical transports its computational efficiency is similar to classical turbulent kinetic energy approaches while preserving one of the main feature of higher order schemes the present extensions to include anisotropic effects in a turbulent kinetic energy approach do not need any ad hoc assumptions and are equivalent to the classical formulation in the isotropic limit the presence of high tracer concentrations in a particle laden plume is taken into account as well as supersonic effects at low mach numbers the turbulent exchange coefficients used in the equations of motion are derived from a set of three coupled differential equations for the horizontal and vertical turbulent energy and the turbulent length scale no turbulent equilibrium is assumed all turbulent quantities are treated prognostically numerical simulations of convective plumes of a typical plinian volcanic eruption with the nonhydrostatic plume model atham reveal that a complex treatment of turbulent quantities is necessary in order to capture the bulk characteristics of the plume such as the plume height the horizontal extent and plume development in time anisotropic effects of turbulence have a significant impact on the stability and internal structure of the plume for the first time results from a fully three dimensional simulation of a volcanic plume are presented because of its general formulation the presented turbulence scheme is suitable for a wide range of atmospheric applications

effect of natural recharge on sea water intrusion in coastal aquifers abstract parametric studies were carried out to investigate the effect of uniform recharge on sea water intrusion into coastal aquifers using a one dimensional finite element model for this purpose uniform recharge over the entire length of intrusion for a wide range of practical aquifers is considered useful relationships have been established between the interface motion and the intensity and duration of uniform recharge these relationships can be used to estimate the repulsion of sea water intrusion owing to rainfall this repulsion under favourable conditions is estimated to reach a maximum of about 5 the effect of uneven distribution of rainfall is demonstrated through an example movement of the interface is also tracked after the cessation of recharge

aquifer recharge using a partially penetrating well with clogging induced permeability reduction abstract well and aquifer clogging is one of the most serious problems restricting the application of managed aquifer recharge mar to address the clogging issue this study proposes an innovative model using partially penetrating wells ppw in confined aquifers while considering the clogging related permeability as an exponentially decayed function of time based on analysis of in situ observation data a combination of hankel transform and finite fourier cosine transform is adopted to solve the model the quasi solutions at early and late times and steady state are also derived using the developed analytical solution the developed solutions can be used to investigate the independent or combined effect of clogging induced permeability reduction well configuration and aquifer anisotropy on groundwater flow dynamics in confined aquifers or inversely used for estimating parameters associated with the clogging effect and aquifer property based on a semi log graphic approach the findings of this study can help for better understanding of the flow behaviors in the confined aquifers suffering clogging and find application in the estimation and prediction of well and aquifer clogging in mar using aquifer injection wells