identification of illite polytype zoning in disseminated gold deposits using reflectance spectroscopy and x ray diffraction potential for mapping with imaging spectrometers x ray diffraction studies of clay minerals from disseminated gold deposits in nevada demonstrate that illite polytypes are often laterally and vertically zoned around ore bodies polytypes act as geothermometers indicating temperatures of ore deposition and thus proximity to the hydrothermal fluids during deposition visible infrared reflectance spectroscopy for field identification and mapping of the illite polytypes is evaluated the results demonstrate that reflectance spectroscopy can be used to assist gold exploration efforts by providing detailed mineralogical information in real time at the field location as the new generation of imaging spectrometers is developed it is likely that subtle spectral differences such as those between the illite polytypes will become useful for remote exploration for gold deposits

source process of very long period events accompanying long period signals at cotopaxi volcano ecuador abstract renewed seismic activity of cotopaxi ecuador began in january 2001 with the increased number of long period lp events followed by a swarm of volcano tectonic vt earthquakes in november 2001 in late june 2002 the activity of very long period vlp 2 s events accompanying lp 0 5 1 s signals began beneath the volcano the vlp waveform was characterized by an impulsive signature which was accompanied by the lp signal showing non harmonic oscillations we observed temporal changes of both the vlp and lp signals from the beginning until september 2003 the vlp signal gradually disappeared and the lp signal characterized by decaying harmonic oscillations became dominant assuming possible source geometries we applied a waveform inversion method to the observed waveforms of the largest vlp event our inversion and particle motion analyses point to volumetric changes of a sub vertical crack as the vlp source which is located at a depth of 2 3 km beneath the northeastern flank the spectral analysis of the decaying harmonic oscillations of lp events shows frequencies between 2 0 and 3 5 hz with quality factors significantly above 100 the increased vt activity and deformation data suggest an intrusion of magma beneath the volcano a release of gases with small magma particles may have repetitively occurred due to the pressurization which was caused by sustained bubble growth at the magma ceiling the released particle laden gases opened a crack above the magma system and triggered the resonance of the crack we interpret the vlp and lp events as the gas release process and the resonance of the crack respectively

discrimination of hydrothermal alteration mineral assemblages at virginia city nevada using the airborne imaging spectrometer abstract the purpose of this study is to use airborne imaging spectrometer data to discriminate hydrothermal alteration mineral assemblages associated with silver and gold mineralization at virginia city nv the data is corrected for vertical striping and sample gradients and converted to flat field logarithmic residuals log residual spectra from areas known to be altered are compared to field spectra for kaolinitic illitic sericitic and propylitic alteration types the areal distributions of these alteration types are estimated using a spectral matching technique both visual examination of spectra and the matching techniques are effective in distinguishing kaolinitic illitic and propylitic alteration types from each other however illitic and sericitic alteration cannot be separated using these techniques because the spectra of illite and sericite are very similar a principal components analysis of 14 channels in the 2 14 2 38 m wavelength region is also successful in discriminating and mapping illitic kaolinitic and propylitic alteration types

evaluation of groundwater quality in northern saudi arabia using multivariate analysis and stochastic statistics groundwater resources available in the paleozoic sedimentary formations form the most prolific source of water supply in the kingdom of saudi arabia in the absence of surface water supplies the available groundwater reserves in these aquifers have been used extensively to fulfill the agricultural and domestic water demands the main purpose of this paper was to evaluate the groundwater quality in the northern western part of saudi arabia using the classical water facies diagram piper and durov plot the more advanced methods of principal component analysis pca for determining the factors controlling the groundwater chemistry and stochastic geostatistics to understand the spatial distribution of different major elements in the groundwater of the study area were employed 40 groundwater samples from bore wells tapping the saq aquifer were collected and analyzed for the major ion chemistry and nitrates groundwater occurs within detrital sandstones of phanerozoic era in saq formations piper plot revealed that most of the water samples belonged to the mixed class ca mg cl so4 type and few samples falling within the ca mg hco3 type na cl type and ca mg so4 type of groundwater facies durov plot pointed towards simple dissolution silicate weathering ion exchange and reverse ion exchange as the main processes governing the chemistry of the area pca resulted in the extraction of two pc accounting for 78 11 of the data variability the extracted pcs pointed towards geogenic factors governing the groundwater quality stochastic geostatistics involved prediction maps of ordinary kriging and indicator kriging which provided detailed indications of spatial distribution of the chemical elements

detectability of minerals on desert alluvial fans using reflectance spectra we analyzed the visible and near infrared reflectance spectra of soil samples collected from desert alluvial and colluvial surfaces in the cuprite mining district nevada these surfaces are downslope from hydrothermally altered volcanic rocks that contain spectrally characteristic minerals such as alunite and kaolinite coarse fractions of the soils on the alluvial fans are mineralogically variable and express the upslope lithologies fine fractions are remarkably similar mineralogically and spectrally in all samples because of dilution of local mineral components by regionally derived windblown dust theoretical models for spectral mixing and for particle size effects were used to model the observed spectral variations diagnostic mineral absorption bands in the spectra of fan materials were enhanced by computationally removing the spectrum of the homogenous fine soil component detection limits for minerals were found to be controlled by the sensitivity of the instrument the spectral contrast between the mineral and the background and the relative brightnesses of the mineral and the background these results show that spectral mixing models are useful for analyzing data with high spectral resolution obtained by field and aircraft spectrometers

geochemistry of the dissolved loads of the liao river basin in northeast china under anthropogenic pressure chemical weathering and controlling factors abstract this study focuses on the chemical and sr isotopic compositions of the dissolved load of the rivers in the liao river basin which is one of the principal river systems in northeast china water samples were collected from both the tributaries and the main channel of the liao river daling river and hun tai river chemical and isotopic analyses indicated that four major reservoirs carbonates gypsum silicates evaporites and anthropogenic inputs contribute to the total dissolved solutes other than carbonate gypsum weathering anthropogenic inputs provide the majority of the solutes in the river water the estimated chemical weathering rates as tds of silicate carbonate gypsum and evaporites are 0 28 3 12 and 0 75 t km2 yr for the main stream of the liao river and 7 01 25 0 and 2 80 t km2 yr for the daliao river respectively the associated co2 consumption rates by silicate weathering and carbonate gypsum weathering are 10 1 and 9 94 103 mol km2 yr in the main stream of the liao river and 69 0 and 80 4 103 mol km2 yr in the hun tai river respectively the daling river basin has the highest silicate weathering rate tdssil 3 84 t km2 yr and the hun tai river has the highest carbonate weathering rate tdscarb 25 0 t km2 yr the raoyang river with an anthropogenic cation input fraction of up to 49 has the lowest chemical weathering rates which indicates that human impact is not a negligible parameter when studying the chemical weathering of these rivers both short term and long term study of riverine dissolved loads are needed to a better understanding of the chemical weathering and controlling factors

mapping the geochemistry of the northern rub al khali using multispectral remote sensing techniques spatial variations in sand sea geochemistry relate to mixing of different sediment sources and to variations in weathering due to problems of accessibility adequate spatial coverage cannot be achieved using field surveys alone however maps of geochemical composition produced from remotely sensed data can be calibrated against limited field data and the results extrapolated over large inaccessible areas this technique is applied to part of the rub al khali in the northern united arab emirates trend surface analysis of the results suggests that the sand sea at this location can be modelled as an east west mixing zone of two spectral components terrestrial reddened quartz sands and marine carbonate sands optical dating of these sediments suggests that dune emplacement occurred rapidly around 10 ka bp when sea level was rising rapidly the spatial distribution of mineralogical components suggests that this phase of dune emplacement resulted from coastal dune sands being driven inland during marine transgression thereby becoming mixed with rubified terrestrial sands copyright 2001 john wiley sons ltd

hypocenter determination in strongly heterogeneous earth models using the shortest path method the shortest path method moser 1991 for the calculation of seismic ray paths and travel times along them can be applied directly in the hypocenter location method proposed by tarantola and valette 1982 it uses the analogy between seismic rays in the earth and shortest paths in networks to construct first arrival times from one point to all other points of a three dimensional grid simultaneously in a fast robust way in earth models of arbitrary complexity doing this for all stations of a seismic array one can find the hypocenter location by minimizing the difference between the observed and the calculated travel times at the stations over the three dimensional grid the concept of probability density functions allows then for a fully nonlinear examination of the uncertainties in the hypocenter location due to uncertainties in the travel time data numerical errors in the calculated travel times and to a limited extent incomplete knowledge about the earth model the result is a three dimensional contour map of regions of equal confidence for the earthquake location the method becomes especially attractive when more than one event recorded by the same array is studied because the calculation of the travel times which is relatively the most time consuming operation has to be done only once the method is applied on the location of an event that occurred on january 18 1989 in israel

natural and anthropogenic factors affecting groundwater quality of an active volcano mt etna italy abstract new geochemical data on dissolved major and minor constituents in 276 groundwater samples from etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation this topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area multivariate statistical analysis reveal 3 sources of solutes a the leaching of the host basalt driven by the dissolution of magma derived co2 b mixing processes with saline brines rising from the sedimentary basement below etna c contamination from agricultural and urban wastewaters the last process highlighted by increased concentrations of so4 no3 ca f and po4 is more pronounced on the lower slopes of the volcanic edifice associated with areas of high population and intensive agriculture however this study demonstrates that natural processes a and b are also very effective in producing highly mineralised waters which in turn results in many constituents b v mg exceeding maximum admissible concentrations for drinking water

geochemistry of fluoride rich groundwater in kolar and tumkur districts of karnataka groundwater is a significant water resource in india for domestic irrigation and industrial needs by far the most serious natural groundwater quality problem in india in terms of public health derives from high fluoride arsenic and iron concentrations hydrogeochemical investigation of fluoride contaminated groundwater samples from kolar and tumkur districts in karnataka are undertaken to understand the quality and potability of groundwater from the study area the level of fluoride contamination the origin and geochemical mechanisms driving the fluoride enrichment majority of the groundwater samples did not meet the potable water criteria as they contained excess 1 5 mg l fluoride dissolved salts 500 mg l and total hardness 75 924 mg l hydrogeochemical facies of the groundwater samples suggest that rock weathering and evaporation crystallization control the groundwater composition in the study area with 50 67 of samples belonging to the ca hco3 type and the remaining falling into the mixed ca na hco3 or ca mg cl type the saturation index values indicated that the groundwater in the study area is oversaturated with respect to calcite and under saturated with respect to fluorite the deficiency of calcium ion concentration in the groundwater from calcite precipitation favors fluorite dissolution leading to excess fluoride concentration

use of airborne imaging spectrometer data to map minerals associated with hydrothermally altered rocks in the northern grapevine mountains nevada and california abstract three flightlines of airborne imaging spectrometer ais data acquired over the northern grapevine mountains nevada and california were used to map minerals associated with hydrothermally altered rocks the data were processed to remove vertical striping normalized using an equal area normalization and reduced to reflectance relative to an average spectrum derived from the data an algorithm was developed to automatically calculate the absorption band parameters band position band depth and band width for the strongest absorption feature in each pixel these parameters were mapped into an intensity hue saturation ihs color system to produce a single color image that summarized the absorption band information this image was used to map areas of potential alteration based upon the predicted relationships between the color image and mineral absorption band individual ais spectra for these areas were then examined to identify specific minerals two types of alteration were mapped with the ais data areas of quartz sericite pyrite alteration were identified based upon a strong absorption feature near 2 21 m a weak shoulder near 2 25 m and a weak absorption band near 2 35 m caused by sericite fine grained muscovite areas of argillic alteration were defined based on the presence of montmorillonite identified by a weak to moderate absorption feature near 2 21 m and the absence of the 2 35 m band montmorillonite could not be identified in mineral mixtures calcite and dolomite were identified based on sharp absorption features near 2 34 and 2 32 m respectively areas of alteration identified using the ais data corresponded well with areas mapped using field mapping field reflectance spectra and laboratory spectral measurements

multispectral remote sensing as stratigraphic and structural tool wind river basin and big horn basin areas wyoming stratigraphic and structural analyses of the wind river basin and big horn basin areas of central wyoming are in progress one result has been the development of an approach to stratigraphic and structural analysis that uses photogeologic and spectral interpretation of multispectral image data to characterize the attitude thickness and lithology of strata new multispectral systems that have only been available since 1982 are used with topographic data to map upper paleozoic and mesozoic strata exposed on the southern margin of the bighorn mountains landsat acquired thematic mapper tm data together with topographic data are used to map lithologic contacts measure dip and strike and develop a stratigraphic column that is correlated with conventional surface and subsurface sections aircraft acquired airborne imaging spectrometer ais and thermal infrared multispectral scanner tims data add mineralogic information to the tm column including the stratigraphic distribution of quartz calcite dolomite smectite and gypsum results illustrate an approach that has general applicability in other geologic investigations that could benefit from remotely acquired information about areal variations in attitude sequence thickness and lithology of strata exposed at the earth s surface application of our methods elsewhere is limited primarily by availability of multispectral and topographic data and quality of bedrock exposures

hydrochemical processes governing groundwater quality of sedimentary aquifers in central saudi arabia and its environmental implications the present study deals with the interpretation of the major processes governing the groundwater chemistry in parts of qassim and riyadh province of saudi arabia the study area that is dominated by agricultural activities is represented by a multi layered aquifer system with sedimentary formations ranging from cambrian to the quaternary present as outcrops groundwater samples from 97 agricultural bore wells in the area were collected and analyzed for 16 physio chemical parameters the evaluation of the main hydrochemical processes affecting the groundwater quality was carried out by interpreting the ionic relationships and hydrochemical facies analysis the interpretation pointed toward evaporation gypsum dissolution and ion exchange as main factors controlling the major ion groundwater chemistry the piper plot showed so4 cl type of groundwater with majority of the samples falling in the zone of permanent hardness due to the formation of non carbonate salts principal component analysis that helps to understand the underlying natural and anthropogenic factors controlling the groundwater chemistry in an area was used in the present study based on which four principal components pcs were extracted the first pc as expected was dominated by the major ions and was attributed to natural processes whereas the extracted components mainly heavy metals in pc 2 3 and 4 pointed toward anthropogenic activities playing an active role in affecting the trace element hydrochemistry

shallow velocity structure of stromboli volcano italy derived from small aperture array measurements of strombolian tremor abstract the properties of the tremor wave field at stromboli are analyzed using data from small aperture arrays of short period seismometers deployed on the north flank of the volcano the seismometers are configured in two semi circular arrays with radii of 60 and 150 m and a linear array with length of 600 m the data are analyzed using a spatiotemporal correlation technique specifically designed for the study of the stationary stochastic wave field of rayleigh and love waves generated by volcanic activity and by scattering sources distributed within the island the correlation coefficients derived as a function of frequency for the three components of motion clearly define the dispersion characteristics for both rayleigh and love waves love and rayleigh waves contribute 70 and 30 respectively of the surface wave power the phase velocities of rayleigh waves range from 1000 m sec at 2 hz to 350 m sec at 9 hz and those for love waves range from 800 to 400 m sec over the same frequency band these velocities are similar to those measured near puu oo on the east rift of kilauea volcano hawaii although the dispersion characteristics of rayleigh waves at stromboli show a stronger dependence on frequency such low velocities are consistent with values expected for densely cracked solidified basalt the dispersion curves are inverted for a velocity model beneath the arrays assuming those dispersions represent the fundamental modes of rayleigh and love waves

seismic source mechanism of degassing bursts at kilauea volcano hawaii results from waveform inversion in the 10 50 s band the current march 2008 to february 2009 summit eruptive activity at kilauea volcano is characterized by explosive degassing bursts accompanied by very long period vlp seismic signals we model the source mechanisms of vlp signals in the 10 50 s band using data recorded for 15 bursts with a 10 station broadband network deployed in the summit caldera to determine the source centroid location and source mechanism we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous medium that takes topography into account the vlp signals associated with the bursts originate in a source region 1 km below the eastern perimeter of halemaumau pit crater the observed waveforms are well explained by the combination of a volumetric component and a vertical single force component for the volumetric component several source geometries are obtained which equally explain the observed waveforms these geometries include 1 a pipe dipping 64 to the northeast 2 two intersecting cracks including an east striking crack dike dipping 80 to the north intersecting a north striking crack another dike dipping 65 to the east 3 a pipe dipping 58 to the northeast intersecting a crack dipping 48 to the west southwest and 4 a pipe dipping 57 to the northeast intersecting a pipe dipping 58 to the west southwest using the dual crack model as reference the largest volume change obtained among the 15 bursts is 24 400 m3 and the maximum amplitude peak to peak of the force is 20 gn each burst is marked by a similar sequence of deflation and inflation trailed by decaying oscillations of the volumetric source the vertical force is initially upward synchronous with source deflation then downward synchronous with source reinflation followed by oscillations with polarity opposite to the volumetric oscillations this combination of force and volume change is attributed to pressure and momentum changes induced during a fluid dynamic source mechanism involving the ascent expansion and burst of a large slug of gas within the upper 150 m of the magma conduit as the slug expands upon approach to the surface and more liquid becomes wall supported by viscous shear forces the pressure below the slug decreases inducing conduit deflation and an upward force on the earth the final rapid slug expansion and burst stimulate vlp and lp oscillations of the conduit system which slowly decay due to viscous dissipation and elastic radiation consideration of the fluid dynamic arguments leads us to prefer the dual crack vlp source model as it is the only candidate model capable of producing plausible values of length scales and pressure changes the magnitudes of the vertical forces observed in the 15 bursts appear consistent with slug masses of 104 to 106 kg

spatial extent of a hydrothermal system at kilauea volcano hawaii determined from array analyses of shallow long period seismicity 2 results we present a probabilistic method to locate the source of seismic events using seismic antennas the method is based on a comparison of the event azimuths and slownesses derived from frequency slowness analyses of array data with a slowness vector model several slowness vector models are considered including both homogeneous and horizontally layered half spaces and also a more complex medium representing the actual topography and three dimensional velocity structure of the region under study in this latter model the slowness vector is obtained from frequency slowness analyses of synthetic signals these signals are generated using the finite difference method and include the effects of topography and velocity structure to reproduce as closely as possible the behavior of the observed wave fields a comparison of these results with those obtained with a homogeneous half space demonstrates the importance of structural and topographic effects which if ignored lead to a bias in the source location we use synthetic seismograms to test the accuracy and stability of the method and to investigate the effect of our choice of probability distributions we conclude that this location method can provide the source position of shallow events within a complex volcanic structure such as kilauea volcano with an error of 200 m

the fluoride in the groundwater of guarani aquifer system the origin associated with black shales of parana basin this work presents petrological and geochemical results of the black shales interval from permian and devonian strata of the parana basin brazil and its relationships with fluoride of groundwater from guarani aquifer system the guarani aquifer located in south brazil uruguay paraguay and argentine presents contents of fluoride higher than the brazilian accepted potability limits several hypotheses have been presented for the origin of the fluoride in the groundwater of the guarani aquifer microcrystalline fluorite was registered in black shales of ponta grossa and irati formations from parana basin the results shown in this work suggest that fluoride present in groundwater of guarani aquifer can be originated in deeper groundwater that circulates in ponta grossa and irati formations the interaction of the groundwater coming from deeper black shales with the groundwater bearing aquifer guarani system occurs through regional fragile structures faults and fractures that constitute excellent hydraulic connectors between the two sedimentary packages the microcrystalline fluorite registered in ponta grossa and irati formations can be dissolved promoting fluoride enrichment in groundwater of these black shales and guarani aquifer system

shallow conduit system at kilauea volcano hawaii revealed by seismic signals associated with degassing bursts 1 eruptive activity at the summit of kilauea volcano hawaii beginning in march 2008 and continuing to the present time is characterized by episodic explosive bursts of gas and ash from a vent within halemaumau pit crater these bursts are accompanied by seismic signals that are well recorded by a broadband network deployed in the summit caldera we investigate in detail the dimensions and oscillation modes of the source of a representative burst in the 1 10 s band an extended source is realized by a set of point sources distributed on a grid surrounding the source centroid where the centroid position and source geometry are fixed from previous modeling of very long period vlp data in the 10 50 s band the source time histories of all point sources are obtained simultaneously through waveform inversion carried out in the frequency domain short scale noisy fluctuations of the source time histories between adjacent sources are suppressed with a smoothing constraint whose strength is determined through a minimization of the akaike bayesian information criterion abic waveform inversions carried out for homogeneous and heterogeneous velocity structures both image a dominant source component in the form of an east trending dike with dimensions of 2 9 2 9 km the dike extends 2 km west and 0 9 km east of the vlp centroid and spans the depth range 0 2 3 1 km the source model for a homogeneous velocity structure suggests the dike is hinged at the source centroid where it bends from a strike e 27 n with northern dip of 85 west of the centroid to a strike e 7 n with northern dip of 80 east of the centroid the oscillating behavior of the dike is dominated by simple harmonic modes with frequencies 0 2 hz and 0 5 hz representing the fundamental mode 11 and first degenerate mode 12 21 of the dike although not strongly supported by data in the 1 10 s band a north striking dike segment is required for enhanced compatibility with the model elaborated in the 10 50 s band this dike provides connectivity between the east trending dike and the new vent within halemaumau pit crater waveform inversions with a dual dike model suggest dimensions of 0 7 0 7 km to 2 6 2 6 km for this segment further elaboration of the complex dike system under halemaumau does not appear to be feasible with presently available data

reflectance spectroradiometry applied to a semi quantitative analysis of the mineralogy of the n4ws deposit carajas mineral province para brazil abstract quantifying the abundance and physicochemical properties of minerals using reflectance spectroradiometry in the visible near infrared and shortwave infrared 400 2500 nm regions is an important tool in mineral exploration in this study the reflectance spectra of drill cores from the world class n4ws iron deposit located in the carajas mineral province brazil were obtained these spectra were validated using x ray fluorescence xrf geochemical analyses and thin sections the reflectance spectra were collected using a fieldspec 3 spectroradiometer asd boulder colorado usa in 10 drill cores the mineralogy of the deposit is mainly hematite with lesser amounts of magnetite goethite quartz kaolinite gibbsite smectite talc carbonate and chlorite the mineralogy of the iron deposit was extracted from the spectral data using the geometry depth and wavelength of absorption features across the reflectance spectrum removed from the continuum the depth of the absorption features is proportional to the mineral abundance and the wavelength is proportional to the mineral chemical composition the diagnostic absorption features of each mineral were used to determine the mineral abundance and composition the final products include the abundance of iron hydro oxide 11 6 root mean square error rmse fe2o3 abundance of aluminous clays rmse 6 al2o3 abundance of talc 8 rmse mgo identification of clay type kaolinite montmorillonite or gibbsite composition of carbonate dolomite vs calcite and composition of chlorite mg vs fe the mineral abundance and composition results provided an effective characterisation of the ore protore and host rocks and showed variations within the ore body

analysis of simultaneous gravity and tremor anomalies observed during the 2002 2003 etna eruption abstract in this paper we discuss the data collected by a large aperture array of broadband seismometers and a continuously recording gravity station during the 2002 2003 eruption of etna volcano italy seismic signals recorded during the eruption are dominated by volcanic tremor whose energy spans the 0 5 5 hz frequency band on three different occasions 12 november 19 20 november and 8 9 december 2002 we observed marked increases of the tremor amplitude up to a factor of 4 which occurred simultaneously with gravity decreases up to 30 gal the three concurrent gravity tremor anomalies last 6 to 12 hours and terminate with rapid up to 2 hours changes after which the signals return back to their original levels based on volcanological observations encompassing the simultaneous anomalies we infer that the accumulation of a gas cloud at some level in the conduit plexus feeding a new eruptive vent could have acted as a joint source this study highlights the potential of joint gravity seismological analyses to both investigate the internal dynamic of a volcano and to improve the confidence of volcanic hazard assessment

performance of the radial semblance method for the location of very long period volcanic signals we investigate the performance of a source location method that com bines multichannel semblance and particle motions and is being increasingly used to obtain estimates of the source locations of very long period vlp seismic signals recorded on volcanoes the method makes use of the radial particle motions and large wavelengths that characterize the vlp events to assess the capabilities of this radial semblance method and to better understand its limitations we quantify the effects of window length noise contents of the signal inaccurate velocity models receiver coverage and orientation errors in the horizontal components of the receiv ers our results show that the semblance method performs best when 1 the noise level is low enough to allow a good characterization of the waveforms 2 the sources are located at distances between one half of the average receiver spacing and about two times the network aperture and 3 the orientations of the horizontal components of the seismometers are known with relative accuracy when these requirements are met the radial semblance method constitutes an adequate tool to obtain preliminary locations of vlp volcanic signals recorded by broadband networks moreover we provide a formula to determine the radial semblance level that should be used to define error regions associated to the estimated source locations

groundwater chemistry patterns in the phreatic aquifer of the central belgian coastal plain the holocene geological evolution of the belgian coastal plain is dominated by a transgression of the north sea silting up of the coastal plain and human intervention impoldering this has led to a typical pattern in groundwater quality which is discussed here for the central part of the coastal plain therefore a database with available groundwater samples is composed water type according to the stuyfzand classification is determined and different hydrosomes and their hydrochemical facies are identified based on this the origin and evolution of the water types is explained using piper plots and geochemical calculations with phreeqc before the impoldering salinising and freshening conditions alternated with a general salinisation of the aquifer after about 3400 bp this results in a dominance of brackish and salt nacl subtypes which are still found in the deeper part of the aquifer the subsequent impoldering resulted in an major freshening of the aquifer leading to nahco3 mghco3 and cahco3 subtypes overall mixing cation exchange carbonate mineral dissolution and oxidation of organic matter are identified as the major processes determining the general water quality the close link between geological evolution water quality and what is still observable today is illustrated with this example of the belgian coastal plain

accurate time frequency wavenumber analysis to study coda waves summary an accurate method is developed to characterize the seismic coda phases recorded by smallaperture arrays the coda is modelled as a superposition of several interfering wavelets identified by their arrival time frequency content backazimuth and apparent velocity of propagation the wavelets are caused by the diffraction and refraction of the direct wavefield by heterogeneities of the propagation medium the deterministic modelling is different from the statistical one generally used to retrieve mean parameters of the medium as the complexity of the medium increases separation of interfering wavelets needs an accurate time frequency wavenumber decomposition method that consists of detection and characterization of the different coherent wavelets propagating through the array detection is realized by mean time frequency decomposition based on the ridges algorithm the multiple signal classification music algorithm allowing a higher separation of simultaneous wavelets in the wavenumber domain is then used to characterize the propagation parameters of the detected components an optimal use of the music algorithm assumes the knowledge of the number of sources that simultaneously propagate through the array the new iterative technique presented here allows the automatic determination of this number of sources this methodology is applied to synthetic signals simulated in a heterogeneous medium results obtained show that i the diffracted wavefield may be more energetic than the primary direct one and ii the relative energy diffracted by each heterogeneity is strongly dependent on the location of the array within the medium the well controlled results obtained for the synthetic examples allow interpretations of the observations made during the annot experiment in the southern french alps in 1998 where four small aperture arrays were deployed with small distances between each array 10 km the time azimuth velocity evolutions determined for the earthquakes recorded during this experiment are used to characterize the heterogeneous structures of the medium

estimation of surface iron oxide abundance with suppression of grain size and topography effects abstract mineral forms of iron oxide such as hematite goethite and jarosite are important because they are widely distributed at the earth s surface and because they are used as indicators for mineral exploration iron oxide abundance in rocks containing these minerals can be estimated from the absorption depth at wavelengths of around 900 nm in a reflectance spectrum but this depth is also affected by extraneous factors such as grain size and topography this paper investigated the effect of grain size on reflectance spectra and proposed a method for estimating iron oxide abundance in surface rocks by using remotely sensed data with suppression of the effects of grain size and topography reflectance spectra were measured in a laboratory from rock powder samples of different grain sizes containing iron oxide minerals while the reflectance increased with decreasing grain size the presence of ferric iron caused the absorption depth to be almost constant at around 900 nm irrespective of the chemical composition of the sample in addition the difference between the reflectance at 550 nm and 760 nm slope was a function of grain size iron oxide abundance can be estimated accurately by mcr 900d which is the maximum absorption depth at the absorption center after the effect of grain size and topography was suppressed by slope and the continuum removal method which takes the ratio between the original spectrum and its continuum respectively correlation of mcr 900d results with datasets of actual spectral and chemical iron oxide laboratory measurements revealed that the mineral forms also need to be considered mcr 900d results were significantly correlated with rock samples classified as containing different forms of iron oxide minerals hematite goethite and jarosite finally mcr 900d was applied to an aviris dataset for the cuprite site in nevada usa the results represented the enrichment zones of iron oxide within hydrothermally altered areas

recharge history and controls on groundwater quality in the yuncheng basin north china environmental isotopes and water quality indicators e g tds and no 3 contents were used to characterize the age recharge history and controls on the quality of groundwater resources in the yuncheng basin north china where extensive extraction occurs for agriculture and domestic supply delta 18 o and delta 2 h values as low as 10 6 and 73 parts per thousand respectively together with low radiocarbon activities 70 pmc indicating a significant component of modern post 1950s recharge the shallow groundwater has higher delta 18 o and delta 2 h values up to 8 1 and 54 parts per thousand that are similar to those in modern summer monsoon rainfall indicating that current recharge is via direct infiltration and or leakage of ephemeral streams during heavy rain events historic recharge rates estimated using radiocarbon ages are between 1 and 10 mm year corresponding to 20 mg l in some deep wells 180 m preferential leakage has occurred near the linyi fault in the northern sushui river basin salinisation nitrate contamination and excessive drawdown of deep groundwater are major concerns for the future of the groundwater resources in this region c 2010 elsevier b v all rights reserved

multisensor classification of sedimentary rocks abstract this paper compares linear discriminant analysis and supervised classification results based on signatures from the landsat thematic mapper tm the thermal infrared multispectral scanner tims and airborne synthetic aperture radar sar alone and combined into extended spectral signatures for seven sedimentary rock units exposed on the margin of the wind river basin wyoming results from a linear discriminant analysis showed that training area classification accuracies based on the multisensor data were improved an average of 15 over tm alone 24 over tims alone and 46 over sar alone with similar improvement resulting when supervised multisensor classification maps were compared to supervised individual sensor classification maps when training area signatures were used to map spectrally similar materials in an adjacent area the average classification accuracy improved 19 using the multisensor data over tm alone 2 over tims alone and 11 over sar alone the conclusion of this study is that certain sedimentary lithologies may be accurately mapped using a single sensor but classification of a variety of rock types can be improved using multisensor data sets that are sensitive to different characteristics such as mineralogy and surface roughness

effect of land use and urbanization on hydrochemistry and contamination of groundwater from taejon area korea abstract taejon metropolitan city located in the central part of south korea has grown and urbanized rapidly the city depends heavily on groundwater as a water resource because of ubiquitous pollution sources the quality and contamination have become important issues for the urban groundwater supply this study has investigated the chemical characteristics and the contamination of groundwater in relation to land use an attempt was made to distinguish anthrophogenic inputs from the influence of natural chemical weathering on the chemical composition of groundwater at taejon groundwater samples collected at 170 locations in the taejon area show very variable chemical composition of groundwater e g electrical conductance ranges from 65 to 1 290 s cm most groundwater is weakly acidic and the groundwater chemistry is more influenced by land use and urbanization than by aquifer rock type most groundwater from green areas and new town residential districts has low electrical conductance and is of ca hco 3 type whereas the chemical composition of groundwater from the old downtown and industrial district is shifted towards a ca cl no 3 so 4 type with high electrical conductance a number of groundwater samples in the urbanized area are contaminated by high nitrate and chlorine and exhibit high hardness the epco 2 that is the co 2 content of a water sample relative to pure water was computed to obtain more insight into the origin of co 2 and bicarbonate in the groundwater the co 2 concentration of groundwater in the urbanized area shows a rough positive relationship with the concentration of major inorganic components the sources of nitrate chlorine and excess co 2 in the groundwater are likely to be municipal wastes of unlined landfill sites leaky latrines and sewage lines chemical data of commercial mineral water from other jurassic granite areas were compared to the chemical composition of the groundwater in the taejon area factor analysis of the chemical data shows that the hco 3 and no 3 concentrations have the highest factor loadings on factor 1 and factor 2 respectively factors 1 and 2 represent major contributions from natural processes and human activities respectively the results of the factor analysis indicate that the levels of ca 2 mg 2 na cl and so 4 2 derive from both pollution sources and natural weathering reactions

modeling the three dimensional structure of macroscopic magma transport systems application to kilauea volcano hawaii we report the results of modeling the three dimensional internal structure of kilauea s magmatic passageways the approach uses a clear plexiglass model containing equally spaced levels upon which well located seismic hypocenters are plotted application of constraining geologic and geophysical criteria to this distributed volume of earthquakes permits the interpretation of seismic structures produced by fracturing in response to locally high fluid pressures four magma transport and storage structures have been identified within and beneath kilauea 1 primary conduit the conduit transporting magma into kilauea s summit storage reservoir rises from the model base 14 6 km to the 6 5 km depth level it is a zone of intense fracturing and inferred intrusion whose horizontal sections are elliptical in planform over its height the average major axis of the component horizontal sections is 3 3 km with an average minor axis of 1 7 km this yields an aspect ratio of 0 52 at the 14 6 km level the strike of the major axis is n67 e during passage from the upper mantle through the oceanic crust this axis rotates in a right handed sense until the strike is n41 w at the 6 5 km level 2 magma chamber complex floor the interval from 6 5 to 5 7 km immediately over the primary conduit is aseismic this suggests differentially high fluid to rock ratios and relatively weak pathways for further vertical transport into higher levels of the storage complex as well as lateral leakage eastward into the mauna ulu staging area for later vertical ascent beneath the upper east rift zone seismicity within the immediately subjacent rocks that form the top of the primary conduit at 6 5 km suggests that this inferred magma rich horizon forms the effective floor of the summit storage complex 3 magma chamber crown intense seismicity over the 1 1 1 9 km depth interval defines an elliptical region in plan view the top of this region has a broad apex with an average major axis of 1 5 km and an average minor axis of 1 1 km producing an aspect ratio of 0 73 this region coincides with the epicentral position of summit vertical displacement maxima during inflationary deformation and is interpreted as a region of intense diking crowning the summit storage complex 4 upper east rift zone pipe from a depth of 5 7 km a cylindrical region of seismicity rises beneath the upper east rift zone to the 1 9 km level where it merges with the subhorizontal upper east rift zone duct this pipe like zone has a mean diameter of 1 4 km and a vertical axis that pierces the surface of the volcano at the intersection of the koae fracture system and the upper east rift zone we suggest this pipe forms a principal connection between the base of the summit storage reservoir and near surface storage compartments and ducts in the upper east rift zone in this role the pipe is suggested to have contributed heavily to mauna ulu s magma supply during 1969 1974 the model of magma transport and storage thus constructed provides a context in which other types of data e g ground deformation and electrical conductivity may be interpreted as well as a means of refining petrological inferences based on lava chemistry

characterization of waste rock associated with acid drainage at the penn mine california by ground based visible to short wave infrared reflectance spectroscopy assisted by digital mapping prior to remediation at the abandoned cu zn penn mine in the foothills massive sulfide belt of the sierra nevada ca acid mine drainage amd was created in part by the subaerial oxidation of sulfides exposed on several waste piles to support remediation efforts a mineralogical study of the waste piles was undertaken by acquiring reflectance spectra measured in the visible to short wave infrared range of light 0 35 2 5 am using a portable digitally integrated pen tablet pc mapping system with differential global positioning system and laser rangefinder support analysis of the spectral data made use of a continuum removal and band shape comparison method and of reference spectral libraries of end member minerals and mineral mixtures identification of secondary fe bearing minerals focused on band matching in the region between 0 43 and 1 3 am identification of sheet and other silicates was based on band shape analysis in the region between 1 9 and 2 4 am analysis of reflectance spectra of characterized rock samples from the mine helped in gauging the spectral response to particle size and mixtures the resulting mineral maps delineated a pattern of accumulation of secondary fe minerals wherein centers of copiapite and jarosite that formed at low ph b3 were surrounded successively by goethite and hematite which mark progressive increases in ph this pattern represents the evolution of acid solutions discharged from the pyritic waste piles and the subsequent accumulation of secondary precipitates by hydrolysis reactions the results highlight the high capacity of the pyritic waste to release further acid mine drainage into the environment as well as the effectiveness of the mapping method to detect subtle changes in surface mineralogy and to produce maps useful to agencies responsible for remediating the site d 2004 elsevier b v all rights reserved

spectral properties 0 4 to 25 microns of selected rocks associated with disseminated gold and silver deposits in nevada and idaho visible near infrared vnir reflectance spectra and midinfrared mir transmission spectra 2 5 25 m were measured for selected rock types from disseminated gold and silver deposits in northern nevada and southern idaho samples from the open pit mines at pinson nevada and delmar idaho were compared to weathered surface samples from a prospect at preble nevada eight characteristics of the disseminated deposits were proposed that could be identified by remote sensing applications of these eight characteristics jasperoids the siliceous replacement of limestones were readily distinguishable from the carbonate host rock and other associated silicate rocks by their spectral characteristics in the mir active or fossil hot spring sites where present near the deposit display similar vnir spectral features at the surface as hydrothermally altered rocks found at depth in the open pit mines however most of the host rocks at the surface above a disseminated gold prospect show few vnir absorption features because of the presence of organic matter vnir spectral features of carbonate were detectable in a few cases immediately adjacent to a jasperoid ammonium spectral features are observed on some of the hydrothermally altered shale surrounding the prospect also suggesting the presence of organic matter because organic matter exerts such a large influence on the spectral character of the host rocks the combined mir and vnir wavelengths are needed for remote discrimination of disseminated gold prospects in the western u s

precise determination of the relative wave propagation parameters of similar events using a small aperture seismic array 1 we propose a method to determine accurately the relative wave propagation parameters apparent slowness and propagation azimuth of a cluster of seismic events with similar waveforms recorded on a seismic array this relative slowness estimate relse method is based on precise measurements of the delays among arrivals of different earthquakes to each of the array receivers delays are determined using interpolations of the cross correlation functions of the earthquake waveforms accurate relative slowness vectors are estimated using a least squares fit of the observed delays to the delays corresponding to the arrivals of plane wave fronts we tested the method using both synthetics and real data in order to understand its resolution capabilities in presence of seismic noise and to assess the uncertainty regions associated with the slowness vector estimates from these analyses we establish a procedure to determine the 90 uncertainty regions associated with the estimates of relative slowness vectors as an example of application of the relse method we analyzed a multiplet composed of 16 similar earthquakes recorded during the 1999 seismic crisis at deception island volcano antarctica using a conventional slowness estimate method produces virtually the same result for every earthquake because of the large uncertainties alternatively using the relse method reduces the uncertainties of the estimates and allows to resolve the detailed distribution of relative apparent slowness vectors our results show that the slowness vectors are aligned within a narrow north south trending band which represents a clue toward the features of the source region and or source distribution we repeated the procedure using different earthquakes as master events the estimated distribution of slowness vectors is similar in every case which demonstrates that our results are independent of the choice of reference event index terms 7299 seismology general or miscellaneous 7203 seismology body wave propagation 7215 seismology earthquake parameters 7230 seismology seismicity and seismotectonics 7280 seismology volcano seismology 8419 keywords seismic arrays slowness vectors multiplet analysis deception island volcano

multivariate statistical analysis of geochemical data as indicative of the hydrogeochemical evolution of groundwater in a sedimentary rock aquifer system summary the study of groundwater hydrogeochemistry of the paleozoic basses laurentides sedimentary rock aquifer system in quebec produced a large geochemical dataset groundwater samples were collected at 153 sites over a 1500 km2 study area and analyzed for major and minor ions the large number of data can lead to difficulties in the integration interpretation and representation of the results two multivariate statistical methods hierarchical cluster analysis hca and principal components analysis pca were applied to a subgroup of the dataset to evaluate their usefulness to classify the groundwater samples and to identify geochemical processes controlling groundwater geochemistry this subgroup consisted of 144 samples and 14 parameters ca2 mg2 na k hco 3 cl so 4 2 fe2 mn2 br sr2 f ba2 hs seven geochemically distinct clusters c1 c7 resulted from the hca samples from clusters c3 c4 c6 and c7 are mostly located in preferential recharge areas the majority of these samples have ca mg hco3 recharge groundwater c3 c6 c7 and na hco3 evolved groundwater c4 samples from the other three clusters c1 c2 c5 are characteristic of an aquifer system under confined conditions the majority of these samples have na hco3 evolved groundwater c1 c5 and na cl ancient groundwater that exhibits elevated concentrations in br c2 in addition to recognizing the importance of hydrogeological conditions on groundwater geochemistry the distribution of clusters also showed the importance of the geological formations on minor and trace elements such as fe2 mn2 sr2 f and ba2 the first five components of the pca account for 78 3 of the total variance in the dataset component 1 is defined by highly positive loadings in na cl and br and is related to groundwater mixing with champlain sea water and solute diffusion from the marine clay aquitard the high positive loadings in ca2 and mg2 of component 2 suggest the importance of dissolution of carbonate rocks in this aquifer system from their characteristic loadings the first two components are defined as the salinity and hardness components respectively components 3 5 are related to more local and geological effects the integration of the hca and the pca with conventional classification of groundwater types as well as with the hydrogeological and geological contexts allowed the division of the region into four main geochemical areas providing an improved regional picture of the aquifer system dynamics and hydrogeochemical evolution of groundwater the following factors were recognized as influencing the evolution of groundwater identified in every geochemical area 1 geological characteristics including sedimentary rock type and till mineralogy 2 hydrogeological characteristics represented by the level of confinement and the hydraulic gradient and 3 the geological history including the latest glaciation and the champlain sea invasion with its integrated approach this hydrogeochemical study contributes to the characterization and understanding of complex groundwater flow systems and provides an example of the long term geochemical evolution of hydrogeological systems after a major perturbation in this case seawater invasion

characteristics of seismic waves composing hawaiian volcanic tremor and gas piston events observed by a near source array a correlation method specifically designed for describing the characteristics of a complex wave field is applied to volcanic tremor and gas piston events recorded by a semicircular array of geos instruments set at the foot of the puu oo crater on the east rift of kilauea volcano hawaii the spatial patterns of correlation coefficients obtained as functions of frequency for the three components of motion over the entire array are similar for gas piston events and tremor and clearly depict dispersive waves propagating across the array from the direction of puu oo the wave fields are composed of comparable amounts of rayleigh and love waves propagating with similar and extremely slow phase velocities ranging from 700 m s at 2 hz to 300 m s at 8 hz the highly cracked solidified lava flow on which the array was deployed and subjacent structure of alternating lava and ash layers formed during repeated eruptions of puu oo since 1983 appear to be responsible for the low velocities observed the results from puu oo stand in sharp contrast to those obtained in an experiment conducted in 1976 on the partially solidified lava lake of kilauea iki rayleigh waves were not observed in kilauea iki but well developed trains of love waves were seen to propagate there with velocities twice as high as those observed near puu oo these differences in the propagation characteristics of surface waves at the two sites may be attributed to the presence of a soft horizontal layer of molten rock in kilauea iki which may have lowered the phase velocity of rayleigh waves more drastically than that of love waves resulting in severe scattering of the rayleigh wave mode on the other hand the thin superficial pahoehoe flow under our array at puu oo may have favored the development of vertical columnar joints more extensively at this location than at kilauea iki which may have reduced the shear moduli controlling the love wave mode the average phase velocities in the frequency band from 2 to 5 hz found at puu oo are roughly similar to those determined for tremor at klyuchevskoy volcano kamchatka but the frequency dependence appears much stronger at puu oo

three dimensional velocity structure of the kilauea caldera hawaii high resolution velocity models 0 5 km resolution of the kilauea caldera region are obtained by the tomographic inversion of both p and s wave arrival times data are from the permanent hawaiian volcano observatory hvo seismic network a broadband seismic network and a temporary array of stations centered on the southern boundary of the caldera a low velocity p wave anomaly is imaged centered on the southeastern edge of the caldera with a velocity contrast of about 10 and a volume of 27 km the vp vs model mimics the spatial extent of the p wave anomaly but is partitioned into two discrete anomalous volumes centered on the southern boundary of the caldera and on the upper east rift of the volcano the corresponding poisson s ratio in these zones is high 0 25 0 32 which is consistent with a densely cracked hot volume which may contain partial melt the large scale features of the models are consistent with results obtained from an earlier larger scale 2 km resolution tomographic image of kilauea volcano based on hvo network data

source process of a long period event at kilauea volcano hawaii summary we analyse a long period lp event observed by a dense seismic network temporarily operated at kilauea volcano hawaii in 1996 we systematically perform spectral analyses waveform inversions and forward modeling of the lp event to quantify its source process spectral analyses identify two dominant spectral frequencies at 0 6 and 1 3 hz with associated q values in the range 10 20 results from waveform inversions assuming six moment tensor and three single force components point to the resonance of a horizontal crack located at a depth of approximately 150 m near the northeastern rim of the halemaumau pit crater waveform simulations based on a fluid filled crack model suggest that the observed frequencies and q values can be explained by a crack filled with a hydrothermal fluid in the form of either bubbly water or steam the shallow hydrothermal crack located directly above the magma conduit may have been heated by volcanic gases leaking from the conduit the enhanced flux of heat raised the overall pressure of the hydrothermal fluid in the crack and induced a rapid discharge of fluid from the crack which triggered the acoustic vibrations of the resonator generating the lp waveform the present study provides further support to the idea that lp events originate in the resonance of a crack

quantitative analysis of the tremor wavefield at etna volcano italy abstract the properties of volcanic tremor wavefield at mt etna volcano italy are investigated using data from two dense small aperture arrays of short period seismometers deployed on the north and south flank of the volcano spectral analysis shows that most of the seismic energy is associated to several narrow spectral peaks spanning the 1 5 hz frequency band analysis of simultaneous recordings evidences that most of these peaks are common to different sites thus suggesting a source effect as the origin of this energy frequency slowness analyses evidence a complex wavefield where body and surface waves alternatively dominate depending on the frequency band and component of motion taken into account surface waves are found to dominate at frequencies below 1 hz and above 3 hz conversely the 0 8 2 3 hz vertical and radial component wavefields at both arrays exhibit a nondispersive nature with apparent velocities spanning the 1 2 s km range particle motion analysis suggests these arrivals are associated to both p and sv waves inciding at shallow angles at the northern array back azimuths of these waves encompass the whole summit crater area at the southern array back azimuths are instead clustered around a direction pointing about 500 m east of the se crater at frequency around 4 hz the dominant direction of wave propagation at the southern site shifts about 30 w pointing to the bocca nuova voragine craters and concordance of location is found with the source imaged by the northern array the 0 8 2 3 hz transverse component of motion depicts velocities of about 0 5 km s a value which is about three times lower than those associated to the vertical and radial components results from polarization analyses at the two array sites depict the dominance of horizontal linear particle motion oriented transversally with respect to the source direction polarization ellipsoids at the stations of the sparse network all depict a quasi horizontal setting with two exceptions the direction of particle motion is always oriented tangentially to the summit volcanic edifice the origin of the large transverse motion observed at the two array sites is thus attributed to sh waves generated by free surface interaction of waves impinging the concave topography the correlation method is used to derive the dispersion properties of short period 0 5 5 hz rayleigh waves from which the shallow shear wave velocity structures are derived for beneath the two semicircular arrays using a probabilistic approach we invert slowness data measured at the two dense arrays for retrieving source location and extent the joint inversion of slowness data from the two arrays point to different sources this observation is interpreted in terms of ray bending associated to lateral heterogeneity and or strong topographic effects on wave propagation once the propagation effects are taken into account the most probable source locations are associated to a shallow region encompassing the summit craters and the eruptive fissures active at the time of the experiment september 1999

deterministic frequency wavenumber methods and direct measurements of rupture propagation during earthquakes using a dense array data analysis data recorded by the smart 1 array in taiwan are used to make the first direct measurements of two dimensional earthquake rupture propagation using frequency wavenumber techniques and ray theory we obtain estimates of the spatial extent duration and directions of rupture propagation during two earthquakes located offshore taiwan our estimates include uncertainties due to errors in fault plane location and orientation velocity structure and slowness ray parameter measured at the array we find that the january 29 1981 ml 6 3 taiwan earthquake ruptured unilaterally updip and toward the west on a 60 dipping 109 striking reverse fault using p waves we find its fault length and duration to be 25 18 km and 7 4 3 4 s respectively s waves indicate a fault length and duration of 27 15 km and 9 4 3 6 s respectively we suggest that the november 14 1986 ml 7 0 hualien taiwan earthquake was triggered by a shallow h 14 km foreshock ml 5 4 which occurred on a subparallel or splay fault approximately 5 s before the mainshock based on p waves rupture propagation during the foreshock is unilateral towards the northeast and slightly downdip on a 58 dipping 38 striking reverse fault its spatial extent and duration are approximately 23 km and 5 4 s the mainshock initiated at greater depth h 34 km than the foreshock with its primary direction of rupture unilateral toward the northeast and slightly updip on a 57 dipping 43 striking reverse fault using p waves we found a spatial extent and duration of 68 15 km and 12 4 2 2 s s waves indicate a similar extent duration and direction of propagation for the mainshock however we found it difficult to distinguish the foreshock and mainshock 5 waves we show by example that these results represent an improvement over what can be obtained using long period t 5 s teleseismic methods comparison of our results with those obtained using teleseismic data suggests either a short duration slip time function or that most slip occurs near the rupture front our results indicate that much of the complexity in the seismograms recorded during these events by the smart 1 array is due to spatial and temporal variations of the source this suggests that at least in some cases predictions of both the phase and amplitude of strong ground motion as a function of time would require a priori knowledge of source properties finally we recommend siting small 10 station dense arrays on land above offshore subduction zones which are considered seismic gaps because they can provide more detailed measurements of rupture propagation than is presently possible

discrimination of iron alteration minerals in visible and near infrared reflectance data field and laboratory studies were conducted to relate the mineralogy of rock and soil samples containing hematite fe2o3 goethite feooh and jarosite kfe3 so4 2 oh 6 to their reflectance properties in visible and near infrared wavelengths field reflectance measurements of regolith containing one or more of these minerals were made in the goldfield nevada mining district with a four channel radiometer the mineralogy and reflectance properties of regolith samples collected from these field measurement sites were then determined by laboratory studies mossbauer spectroscopy was used to identify the iron minerals present and their relative proportions the reflectance spectra of samples containing hematite and goethite were characterized by a reflectance minimum near 900 nm the location of this minimum could be accounted for by the relative proportions of hematite and goethite present in the samples under certain conditions it may be feasible to estimate the relative proportions of hematite and goethite on the earth s surface by determining the location of this near infrared reflectance minimum in high spectral resolution remote sensing data in addition the field measurements suggest that the ratio of band passes at 852 and 982 nm may be used to distinguish qualitatively among hematite goethite and jarosite thus maps of the distribution of these minerals may be derived from scanner images acquired in those band passes

temporal evolution of long period seismicity at etna volcano italy and its relationships with the 2004 2005 eruption abstract between december 2004 and august 2005 more than 50 000 long period events lp accompanied by very long period pulses vlp were recorded at mt etna encompassing the effusive eruption which started in september 2004 the observed activity can be explained by the injection of a gas slug formed within the magmatic column into an overlying cavity filled by either magmatic or hydrothermal fluids thus triggering cavity resonance although a large number of lp events exhibit similar waveforms before the eruption they change significantly during and after the eruption we study the temporal evolution of the lp vlp activity in terms of the source movement change of the waveforms temporal evolution of the dominant resonance frequencies and the source q factor and changes in the polarization of the signal the lp source locations before and after the eruption respectively do not move significantly while a slight movement of the vlp source is found the intensity of the lp events increases after the eruption as well as their dominant frequency and q factor while the polarization of the signals changes from predominantly transversal to pure radial motion although in previous studies a link between the observed lp activity and the eruption was not found these observations suggest that such a link was established at the latter end of the eruptive sequence most likely as a consequence of a reestablishment of the pressure balance in the plumbing system after it was undermined due to the discharge of large amounts of resident magma during the eruption based on the polarization properties of the signal and geological setting of the area a fluid filled crack is proposed as the most likely source geometry the spectral analysis based on the autoregressive models sompi is applied to the signals in order to analyse the resonance frequencies and the source q factors the results suggest water and basalt at low gas volume fraction as the most likely fluids involved in the source process using theoretical relations for the slow waves radiated from the fluid filled crack we also estimate the crack size for both fluids respectively

array analysis of the seismic wavefield of long period events and volcanic tremor at arenal volcano costa rica we use wavefield decomposition methods time domain crosscorrelation and frequency domain music to analyze seismic data recorded by a dense small aperture array located 2 km west of arenal volcano costa rica and operated during 2 5 days the recorded wavefield is dominated by harmonic tremor and includes also spasmodic tremor and long period lp events we find that the initial stages of lp events are characterized by three different wave arrivals these arrivals propagate with similar back azimuths pointing to the volcano summit 80 n and increasing apparent slownesses of 0 4 1 1 and 1 7 s km spasmodic tremors can not be regarded as coherent signals on the contrary harmonic tremors are highly coherent characterized by the stability of the apparent slowness vector estimates apparent slownesses lay in the range 1 2 s km back azimuths point in the general direction of the volcano but with a large variability 40 120 n nevertheless there are long term variations and evidences of multiple simultaneous components in the harmonic tremor wavefield these observations suggest that lp events and tremor are generated in a shallow source area near the volcano summit although they do not share exactly the same source region or source processes the tremor source is located in the shallowest part of the plumbing system beneath the lava crust this dynamic region is subject to complex fluctuations of the physical conditions degassing events at different locations of this region might generate variable seismic radiation patterns the effects of topography and heterogeneous shallow structure of the volcano may amplify these variations and produce the wide directional span observed for volcanic tremor on the other hand the lp source seems to be more repeatable lp events are likely triggered by fragmentation of the fluid flow in a slightly deeper portion of the volcanic conduits

inferences on the source of long period seismicity at campi flegrei from polarization analysis and reconstruction of the asymptotic dynamics in the present paper we analyse long period lp events and seismic noise recorded at campi flegrei during the uplift episode of 2004 2006 the results of a detailed polarization analysis indicate that the large number of lps detected during the seismic crisis were accompanied by a sustained activity consisting of very low energy volcanic signals these weak volcanic signals which are usually absent in ambient noise recorded in the studied area and lp events have similar properties namely they are radially polarized towards the same lp source the large dataset analysed allows us to study the statistics of the polarization leading to the extraction of the average properties of the volcanic signals an estimate of the complexity of the system can be provided by the degrees of freedom necessary to describe the asymptotic dynamics in a reconstructed phase space this analysis shows that both lps and low energy signals can be described by a low dimensional dynamical system while ambient noise unrelated to volcanic activity is higher dimensional based on these observations we interpret the phenomena observed during the seismic crisis in the framework of the theory of self oscillating systems in which lps and low energy signals represent self oscillations generated by a persistent hydrothermal source

controls on elevated fluoride and arsenic concentrations in groundwater from the yuncheng basin china chemical analysis of groundwater and sediments was carried out to investigate causes of elevated f 1 5 6 6 mg l and as concentrations 10 27 mu g l one sample affected by local contamination with 4870 mu g l as in groundwater from the yuncheng basin northern china groundwater from 9 out of 73 wells contains both f and as concentrations above world health organisation safe drinking guidelines 1 5 mg l and 10 mu g l respectively f concentrations above safe levels are more widespread than as 27 vs 12 wells the elevated as and f concentrations represent a significant health risk as groundwater is widely used to supply agricultural and domestic water in the region high f and as concentrations occur in shallow groundwater affected by agriculture and deep groundwater with long residence times 13 ka that shows little sign of anthropogenic influence the strong positive correlation between groundwater f cl and as cl ratios r 2 0 98 and 0 77 in shallow and deep groundwater respectively indicates that these elements are mobilized and enriched by common processes positive correlations between f and as concentrations and na ca ratios r2 0 67 and 0 46 respectively indicate that groundwater major ion chemistry plays a significant role in mobilizing f and as mobilization likely occurs via de sorption of as and f anions e g haso 4 2 and f from hydrous metal oxides moderate positive correlations between ph and as and f concentrations r 2 0 36 and 0 17 respectively indicate that high ph may favour de sorption while hco 3 may act as a sorption competitor high groundwater na ca ratios likely result from cation exchange while ph and hco 3 contents are predominantly controlled by carbonate weathering reactions sediments from the area were reacted with various water solutions producing f concentrations between 0 49 and 2 7 mg l and as concentrations between 0 51 and 16 7 mu g l up to 45 more f and 35 more as were released when sediments were reacted with a na rich ca poor solution compared to a ca rich solution this is consistent with increased mobilization of f and haso 4 2 by na rich ca poor groundwater increasing f and as concentrations across a wide area caused by high levels of pumping is a potential future health concern c 2011 elsevier ltd all rights reserved

imaging the crustal magma sources beneath mauna loa and kilauea volcanoes hawaii three dimensional seismic p wave traveltime tomography is used to image the magma sources beneath mauna loa and kilauea volcanoes hawaii high velocity bodies 6 4 km s in the upper 9 km of the crust beneath the summits and rift zones of the volcanoes correlate with zones of high magnetic intensities and are interpreted as solidified gabbro ultramafic cumulates from which the surface volcanism is derived the proximity of these high velocity features to the rift zones is consistent with a ridge spreading model of the volcanic flank southeast of the hilina fault zone along the south flank of kilauea low velocity material

geochemical and isotopic evidence for palaeo seawater intrusion into the south coast aquifer of laizhou bay china this research aims to improve the current knowledge of groundwater salinisation processes in coastal aquifers using combined hydrochemical and isotopic parameters and inverse hydrochemical modelling field investigations were conducted in laizhou bay which is the area most seriously affected by seawater intrusion in north china during three sampling campaigns along a vertical transect in the changyiliutuan area 95 ground and surface water samples were collected for major ion and isotope analysis

mineralogical characterization of rock surfaces formed by hydrothermal alteration and weathering application to remote sensing the value of 50 mu m was used as an approximate maximum penetration depth to include all mineral species which may contribute to a reflectance signal jarosite and alunite occur only in altered areas whereas hematite and goethite occur in both altered and unaltered areas incorporation of aluminum into hematite occurs only in unaltered areas the spectral shift to longer wavelengths which accompanies aluminum substitution should be useful in delineating mineralized zones modified journal abstract

assessing the impact of natural and anthropogenic activities on groundwater quality in coastal alluvial aquifers of the lower liaohe river plain ne china abstract the lower liaohe river plain lrp is an economically and ecologically important area situated on an alluvial plain where anthropogenic activities are very intensive field investigations were conducted in the lrp and 15 water quality parameters surveyed at 216 wells during september and october of 2009 and 2010 these showed significant variation in the hydrochemistry of groundwater throughout the plain a piper plot was used to identify the major geochemical processes occurring in the entire plain principal components analysis pca was used to identify various underlying natural and anthropogenic processes that created these distinct water types the stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the liaohe river delta five principal components pcs were extracted in terms of pca which can be invoked to explain 82 of the total variance in water quality parameters the pca results can be categorized by five major factors 1 holocene transgression and mixing 2 surface water infiltration 3 multi factor processes 4 rainfall and agricultural fertilizer contamination and 5 geogenic f enrichment this study demonstrates that the great variation of groundwater hydrochemistry in the lrp should be attributed to both natural and anthropogenic processes

wavefield properties of a shallow long period event and tremor at kilauea volcano hawaii the wavefields of tremor and a long period lp event associated with the ongoing eruptive activity at kilauea volcano hawaii are investigated using a combination of dense small aperture 300 m and sparse large aperture 5 km arrays deployed in the vicinity of the summit caldera measurements of azimuth and slowness for tremor recorded on the small aperture array indicate a bimodal nature of the observed wavefield at frequencies below 2 hz the wavefield is dominated by body waves impinging the array with steep incidence these arrivals are attributed to the oceanic microseismic noise in the 2 6 hz band the wavefield is dominated by waves propagating from sources located at shallow depths 1 km beneath the eastern edge of the halemaumau pit crater the hypocenter of the lp event determined from frequency slowness analyses combined with phase picks appears to be located close to the source of tremor but at a shallower depth 0 1 km the wavefields of tremor and lp event are characterized by a complex composition of body and surface waves whose propagation and polarization properties are strongly affected by topographic and structural features in the summit caldera region analyses of the directional properties of the wavefield in the 2 6 hz band point to the directions of main scattering sources which are consistent with pronounced velocity contrasts imaged in a high resolution three dimensional velocity model of the caldera region the frequency and q of the dominant peak observed in the spectra of the lp event may be explained as the dominant oscillation mode of a crack with scale length 20 100 m and aperture of a few centimeters filled with bubbly water the mechanism driving the shallow tremor appears to he consistent with a sustained excitation originating in the oscillations of a bubble cloud resulting from vesiculation and degassing in the magma

diagenetic alteration of the wingate formation possible indications of hydrocarbon microseepage lisbon valley utah at most localities in southeastern utah the wingate formation is a sandstone that exhibits generally uniform mineralogy and appearance along the southwest dipping flank of the lisbon valley anticline however substantial differences occur in the spatial distribution of authigenic kaolinite and hematite that permit differentiation of three outcrop areas the northern and southern portions of this flank of the anticline are white bleached the bulk of the remaining centrally located wingate outcrops are uniformly red unbleached because of hematite clay coatings on constituent grains bleached rocks lack these grain coatings in addition most of the quartz grains in the bleached rocks have overgrowths compared to the other areas the northern bleached rocks have three to five times more authigenic kaolinite half the porosity twice as many altered feldspars and one third as much mixed layer clay both northern and southern bleached rocks contain hematite pseudomorphs after pyrite and the norther

precursory swarms of long period events at redoubt volcano 1989 1990 alaska their origin and use as a forecasting tool abstract during the eruption of redoubt volcano from december 1989 through april 1990 the alaska volcano observatory issued advance warnings of several tephra eruptions based on changes in seismic activity related to the occurrence of precursory swarms of long period lp seismic events dominant period of about 0 5 s the initial eruption on december 14 occurred after 23 years of quiescence and was heralded by a 23 hour swarm of lp events that ended abruptly with the eruption after a series of vent clearing explosions over the next few days dome growth began on december 21 another swarm with lp events similar to those of the first began on the 26th and ended in a major tephra eruption on january 2 eruptions continued over the next two weeks and then ceased until february 15 when a large eruption initiated a long phase of repetitive dome building and dome destroying episodes that continued into april warnings were issued before the major events on december 14 and january 2 but as the eruptive sequence continued after january 2 the energy of the swarms decreased and forecasting became more difficult a significant but less intense swarm preceded the february 15 eruption which was not forecast this eruption destroyed the only seismograph on the volcanic edifice and stymied forecasting until march 4 when the first of three new stations was installed within 3 km of the active vent from march 4 to the end of the sequence on april 21 there were eight eruptions six of which were preceded by detectable swarms of lp events although weak these swarms provided the basis for warnings issued before the eruptions on march 23 and april 6 the initial swarm on december 13 had the following features 1 short duration 23 hours 2 a rapidly accelerating rate of seismic energy release over the first 18 hours of the swarm followed by a decline of activity during the 5 hours preceding the eruption 3 a magnitude range from 0 4 to 1 6 4 nearly identical lp signatures with a dominant period near 0 5 s 5 dilatational first motions everywhere and 6 a stationary source location at a depth of 1 4 km beneath the crater this occurrence of long period events suggests a model involving the interaction of magma with groundwater in which magmatic gases steam and water drive a fixed conduit at a stationary point throughout the swarm the initiation of that sequence of events is analogous to the failure of a pressure relief valve connecting a lower supercharged magma dominated reservoir to a shallow hydrothermal system a three dimensional model of a vibrating fluid filled crack recently developed by chouet is found to be compatible with the seismic data and yields the following parameters for the lp source crack length 280 380 m crack width 140 190 m crack thickness 0 05 0 20 m crack stiffness 100 200 sound speed of fluid 0 8 1 3 km s compressional wave speed of rock 5 1 km s density ratio of fluid to rock 0 4 and ratio of bulk modulus of fluid to rigidity of rock 0 03 0 07 the fluid filled crack is excited intermittently by an impulsive pressure drop that varies in magnitude within the range of 0 4 to 40 bar such disturbance appears to be consistent with a triggering mechanism associated with choked flow conditions in the crack

time variation of spectral and wavefield features of volcanic tremor at mt etna january june 1999 abstract we have studied the volcanic tremor recorded at mt etna during january june 1999 by using three component seismic stations this time period was characterised by both explosive and effusive eruptions occurring at the summit craters we found significant time variations in the trend of the overall spectral amplitude of tremor as well as in the dominant spectral peaks moreover the tremor wavefield features polarization particle motion and ratios between the amplitude of the three components of the ground velocity have been studied too confirming significant time variations this leads us to suggest the existence of at least two tremor sources a shallow one mainly characterised by relatively high frequencies 3 5 7 hz is linked to the upper portions of the active conduits and directly related to the observed eruptive activity the latter deeper source was active for only a few weeks and characterised by frequencies lower than about 2 5 hz it had no relationship with the observed eruptive activity and was speculatively related to the gas exsolution from fresh magma refilling a small batch

analysis of surface deformation data kilauea volcano hawaii october 1966 to september 1970 a least squares inversion technique has been applied to surface displacement measurements made at kilauea volcano hawaii in an attempt to locate centers of intrusive activity utilizing analytic expressions for the displacement field arising from dilatational sources in an elastic half space this technique allows for the simultaneous inversion of level tilt and horizontal distance measurements in terms of the location and volume of the intrusive body a variety of simple elastic model geometries representing possible shapes for intrusive bodies in the summit region of kilauea were examined none of the model geometries considered significantly improved the quality of the model fit to the available data over that obtained by a point source model calculations based on elastic models to consecutive level surveys were compared to available tilt data and horizontal distance measurements these comparisons indicate occasional departures from ideal elastic behavior the departure of measured tilt patterns from calculated tilt values may be the result of earthquake activity or episodic block movements superimposed on larger elastic displacements the departure of measured and calculated horizontal measurements reveals a gradual north south extensional strain across the summit caldera of kilauea in addition to the elastic uplift and subsidence patterns determined from level surveys a minimum estimate for the magma supply rate to kilauea is provided by the elastic models to the level data the average rate for the period from october 1966 to september 1970 was 0 07 km3 per year

temporal variations of repeating low frequency volcanic earthquakes at ngauruhoe volcano new zealand abstract a persistent swarm of micro earthquakes was observed at ngauruhoe volcano new zealand from 2005 to 2010 marking the first unrest episode at the volcano since 1975 detailed waveform and spectral analysis of the continuous seismic record revealed eight earthquake families f1 f8 within a sequence of 8561 low frequency earthquakes an analysis of stacked waveforms of each family allowed the families to be linked systematically into four super families that may indicate four different mechanisms and or source locations or geometries the first super family mostly occurred in 2005 and showed stable waveforms and no significant evolution the second super family was dominant over a two year period starting in mid 2006 and displayed a slow evolution with progressively higher frequency the third super family emerged from early 2008 with intermittent occurrence and high seismicity and progressed to higher peak frequency in 2010 the fourth super family was mainly observed from late 2008 to mid 2009 and had the highest peak frequency in 2009 the observed evolutionary pattern may be driven by a modest multi year input of gas and heat from a deeper relict magmatic zone into the shallow volcano hydrothermal system the interplay of gas from below and seasonal meltwater from above may have modulated the seismic activity and may relate to repeated over pressurization and failure of constricted evolving pathways within a pervasive crack system

high precision relocation of long period events beneath the summit region of kilauea volcano hawai i from 1986 to 2009 long period 0 5 5 hz lp seismicity has been recorded for decades in the summit region of kilauea volcano hawai i and is postulated as linked with the magma transport and shallow hydrothermal systems to better characterize its spatiotemporal occurrence we perform a systematic analysis of 49 030 seismic events occurring in the kilauea summit region from january 1986 to march 2009 recorded by the 50 station hawaiian volcano observatory permanent network we estimate 215 437 p wave spectra considering all events on all stations and use a station averaged spectral metric to consistently classify lp and non lp seismicity we compute high precision relative relocations for 5327 lp events 43 of all classified lp events using waveform cross correlation and cluster analysis with 6 4 million event pairs combined with the source specific station term method the majority of intermediate depth 5 15 km lps collapse to a compact volume with remarkable source location stability over 23 years indicating a source process controlled by geological or conduit structure

investigating the source characteristics of long period lp seismic events recorded on piton de la fournaise volcano la reunion abstract magmatic and hydrothermal processes play a significant role in generating seismicity at active volcanoes these signals can be recorded at the surface and can be used to obtain an insight into the volcano s internal dynamics long period lp events are of particular interest as they often accompany or precede volcanic eruptions but they are still not well understood piton de la fournaise volcano la reunion island is one of the most active volcanoes in the world however lp events are rarely recorded there a seismic network of 20 broadband seismometers has been operational on piton de la fournaise volcano since november 2009 between november 2009 and january 2011 the volcano erupted five times but only 15 lp events were recorded three of these eruptions were preceded by lp events and several lp events were recorded during an intrusive phase a family of three repeating lp events exists within the dataset in order to characterize these events we locate and perform moment tensor inversion on the lp family the lp events are located within the summit crater at shallow depths

assessment of the impact of anthropogenic activities on the groundwater hydrology and chemistry in tarsus coastal plain mersin se turkey using fuzzy clustering multivariate statistics and gis techniques summary tarsus coastal plain tcp is an economically and ecologically important area situated in between the fertile fluvio deltaic plains of two rivers delicay and tarsus mersin se turkey where anthropogenic activities agricultural industrial and domestic are very intense twenty four water quality parameters were surveyed at 193 groundwater and 10 surface water sites during august 2008 the objective was to characterize the physico chemical properties of groundwaters in tcp assess the impact of anthropogenic activities on the groundwater hydrology and chemistry and identify the major hydrogeochemical processes occurring in the area groundwater samples were grouped into hydrochemically distinct and spatially continuous four water classes i e c1 c2 c3 and c4 using the fuzzy c means fcm clustering method where membership values were interpolated using the ordinary kriging technique principal components analysis pca was used to decipher various underlying natural and anthropogenic processes creating these distinct water classes four principal components pcs were extracted in pca which explained more than 73 of the total variance in water quality major factors responsible for the variations in chemistries of water classes are identified as 1 water rock interaction and nitrate contamination 2 salinization by seawater intrusion and evaporite dissolution 3 geogenic anthropogenic cr fe and mn and 4 anthropogenic zn pollution overexploitation of the aquifer is clearly evident especially at settlements located near the coastal zone where the water table is lowered 2 5 m below the sea level salinization is well known in the area and is attributed not only to seawater intrusion but also to dissolution of evaporitic series from the handere formation hydrochemical evidence also suggest that in the area subsurface paleo river channels and the deposits infilling the ancient lagoon area within quaternary recent alluvial deposits act as significant hydrological features where preferential groundwater flow occurs along them

fluoride concentrations in a crystalline bedrock aquifer marathon county wisconsin water samples from 2 789 private water supply wells in marathon county wisconsin reveal that fluoride concentrations in the crystalline bedrock range from 0 01 to 7 60 mg l with 0 6 of the values exceeding the environmental protection agency s epa s maximum contaminant level of 4 mg l and 8 6 exceeding the epa s secondary maximum contaminant level of 2 0 mg l roughly a quarter of the wells contain dissolve fluoride within the range considered optimal for human health between 0 5 and 1 5 mg l whereas 63 3 fall below 0 5 mg l consistent with studies conducted in other regions felsic rocks have significantly higher fluoride concentrations than mafic and metasedimentary rocks syenites yield the most fluoriferous groundwaters but the highest median concentration occurs in a sodium plagioclase granite a relationship between plagioclase composition and fluoride concentrations suggests that dissolved fluoride levels are controlled by fluorite solubility and that higher fluoride concentrations are found in soft sodium rich groundwater

mapping the sources of the seismic wave field at kilauea volcano hawaii using data recorded on multiple seismic antennas seismic antennas constitute a powerful tool for the analysis of complex wave fields well designed antennas can identify and separate components of a complex wave field based on their distinct propagation properties the combination of several antennas provides the basis for a more complete understanding of volcanic wave fields including an estimate of the location of each individual wave field component identified simultaneously by at least two antennas we used frequency slowness analyses of data from three antennas to identify and locate the different components contributing to the wave fields recorded at kilauea volcano hawaii in february 1997 the wave field components identified are 1 a sustained background volcanic tremor in the form of body waves generated in a shallow hydrothermal system located below the northeastern edge of the halemaumau pit crater 2 surface waves generated along the path between this hydrothermal source and the antennas 3 back scattered surface wave energy from a shallow reflector located near the southeastern rim of kilauea caldera 4 evidence for diffracted wave components originating at the southeastern edge of halemaumau and 5 body waves reflecting the activation of a deeper tremor source between 02 hr 00 min and 16 hr 00 min hawaii standard time on 11 february

effect of different land use land cover on karst hydrogeochemistry a paired catchment study of chenqi and dengzhanhe puding guizhou sw china summary rainfall spring stage water temperature ph and conductivity in the paired karst spring catchments of chenqi and dengzhanhe which shared the same climatic condition but different land use land cover lulc at puding guizhou province sw china were monitored by two high resolution multi parameter auto recordable instrument of ctdp300 during the hydrological year of september 2007 september 2008 other monthly hydrogeochemical and carbon isotopic 13c variations in the paired karst catchments during the same hydrological year were also investigated a thermodynamic model was used to link the continuous data to monthly hydrogeochemical data allowing the calculation of co2 partial pressure pco2 and calcite saturation index sic on a continuous basis the primary study objective was to understand how the karst processes and karst hydrogeochemistry respond to different lulc which is essential to assessing the karst related carbon cycle marked seasonal and storm scale variations were found for ph conductivity pco2 sic and 13c of the two springs indicating that both springs were dynamic and variable systems however there were differences in the magnitude and direction of the variations of these features between the two springs the higher pco2 and hco 3 concentration and lower ph sic and 13c in chenqi spring than those in dengzhanhe spring tend to be related to the difference in lulc between chenqi and dengzhanhe spring catchments in the chenqi spring catchment there was larger soil cover and the paddy land was located in the discharge area both of which produced and kept more co2 a major driving agent for the karst processes and lower 13c in the soil aquifer system while in the dengzhanhe spring catchment area there was larger bare carbonate rock occurrence and the paddy land was located mainly in the recharge area moreover the ph increased and pco2 decreased generally in chenqi spring after rainfall possibly due to more carbonate dissolution in the larger soil cover rich in limestone fragments in the spring catchment while the ph decreased and pco2 increased generally in dengzhanhe spring after rainfall all these differences show that soil cover and land use pattern played important roles in the karst processes in other words the karst hydrogeochemistry and the karst related carbon cycle could be regulated effectively by different lulc in addition the higher concentrations of ca2 so 4 2 mg2 and conductivity of dengzhanhe spring were due to the dissolution of more gypsum and dolomite minerals in the strata of dengzhanhe spring catchment therefore the karst hydrogeochemical parameters including ph conductivity hco 3 ca2 mg2 so 4 2 pco2 sic and 13cdic could serve as good indicators of different lulc and the other environmental changes

effects of topography and crustal heterogeneities on the source estimation of lp event at kilauea volcano summary the main goal of this study is to improve the modelling of the source mechanism associated with the generation of long period lp signals in volcanic areas our intent is to evaluate the effects that detailed structural features of the volcanic models play in the generation of lp signal and the consequent retrieval of lp source characteristics in particular effects associated with the presence of topography and crustal heterogeneities are here studied in detail we focus our study on a lp event observed at kilauea volcano hawaii in 2001 may a detailed analysis of this event and its source modelling is accompanied by a set of synthetic tests which aim to evaluate the effects of topography and the presence of low velocity shallow layers in the source region the forward problem of green s function generation is solved numerically following a pseudo spectral approach assuming different 3 d models the inversion is done in the frequency domain and the resulting source mechanism is represented by the sum of two time dependent terms a full moment tensor and a single force synthetic tests show how characteristic velocity structures associated with shallow sources may be partially responsible for the generation of the observed long lasting ringing waveforms when applying the inversion technique to kilauea lp data set inversions carried out for different crustal models led to very similar source geometries indicating a subhorizontal cracks on the other hand the source time function and its duration are significantly different for different models these results support the indication of a strong influence of crustal layering on the generation of the lp signal while the assumption of homogeneous velocity model may bring to misleading results

integrated analysis of high resolution field and airborne spectroradiometer data for alteration mapping oatman epithermal gold deposit in northwest arizona pervasive argillic and wall rock phyllic and propylitic alteration discrimination of these zones rests on identification of the dominant alteration minerals alunite illite mica and chlorite modified journal abstract

array measurements and modeling of sources of shallow volcanic tremor at kilauea volcano hawaii we show that resonances in near surface layers path effects or a combination of near surface resonances and source resonances source effects could be responsible for the sharp spectral peaks found in the records of gas piston activity and volcanic tremor recorded near puu oo crater on kilauea volcano hawaii two types of sources are found to be compatible with observations and can not be distinguished using our data in one model impulsive explosion point sources are embedded in the puu oo structure in the other model impulsive point sources of pressure excite the resonances of a fluid filled crack embedded in that structure both models require shallow sources z 100 m and display a strong dependence of the radiated spectrum on source depth over a depth range comparable to the overall thickness of the surficial layers based on these results it may be possible to track changes in source depth through temporal changes in observed spectra a potentially useful tool for monitoring volcanic activity at this site we estimate the depth and spatial extent of volcanic tremor and gas piston activity using two dense arrays with respective apertures of 800 and 120 m located near puu oo measurements of slowness ray parameter and azimuth as a function of time clearly indicate that the sources of volcanic tremor and gas piston activity are located beneath or in close proximity to the puu oo crater at depths shallower than approximately 1 km based on slowness and particle motion analyses we find that the records of volcanic tremor and gas piston events at puu oo consist of a complex combination of body and surface waves

the character of long term eruptions inferences from episodes 50 53 of the pu u ō ō kūpaianaha eruption of kīlauea volcano the pu u k paianaha eruption on the east rift zone of k lauea began in january 1983 the first 9 years of the eruption were divided between the pu u 1983 1986 and k paianaha 1986 1992 vents each characterized by regular predictable patterns of activity that endured for years in 1990 a series of pauses in the activity disturbed the equilibrium of the eruption and in 1991 the output from k paianaha steadily declined and a short lived fissure eruption broke out between k paianaha and pu u in february 1992 the k paianaha vent died and 10 days later eruptive episode 50 began as a fissure opened on the uprift flank of the pu u cone for the next year the eruption was marked by instability as more vents opened on the flank of the cone and the activity was repeatedly interrupted by brief pauses in magma supply to the vents episodes 50 53 constructed a lava shield 60 m high and 1 3 km in diameter against the steep slope of the pu u cone by 1993 the shield was pockmarked by collapse pits as vents and lava tubes downcut as much as 29 m through the thick deposit of scoria and spatter that veneered the cone as the vents progressively lowered the level of the pu u pond also dropped demonstrating the hydraulic connection between the two the downcutting helped to undermine the prominent pu u cone which has diminished in size both by collapse as a large pit crater formed over the conduit and by burial of its flanks intervals of eruptive instability such as that of 1991 1993 accelerate lateral expansion of the subaerial flow field both by producing widely spaced vents and by promoting surface flow activity as lava tubes collapse and become blocked during pauses