estimation of quality factors from cmp records estimates of the quality q factor are commonly obtained from vertical seismic data or stacked surface seismic data this paper describes a method that allows q factor to be estimated directly from common midpoint cmp gathers absorption of the wavefield is dependent on three parameters frequency traveltime in the medium and medium q factor assuming that the amplitude spectrum of the seismic source signature may be modeled by that of a ricker wavelet we derive an analytical relation between q factor and seismic data peak frequency variation both along offset and vertical time direction the q factor is estimated from cmp gathers using a layer stripping approach

assessment of solute fluxes beneath an orchard irrigated with treated sewage water a numerical study 1 detailed numerical simulations were used to analyze water flow and transport of nitrate chloride and a tracer solute in a 3 d spatially heterogeneous variably saturated soil originating from a citrus orchard irrigated with treated sewage water tsw considering realistic features of the soil water plant atmosphere system results of this study suggest that under long term irrigation with tsw because of nitrate uptake by the tree roots and nitrogen transformations the vadose zone may provide more capacity for the attenuation of the nitrate load in the groundwater than for the chloride load in the groundwater results of the 3 d simulations were used to assess their counterparts based on a simplified deterministic 1 d vertical simulation and on limited soil monitoring results of the analyses suggest that the information that may be gained from a single sampling point located close to the area active in water uptake by the tree roots or from the results of the 1 d simulation is insufficient for a quantitative description of the response of the complicated 3 d flow system both might considerably underestimate the movement and spreading of a pulse of a tracer solute and also the groundwater contamination hazard posed by nitrate and particularly by chloride moving through the vadose zone this stems mainly from the rain that drove water through the flow system away from the rooted area and could not be represented by the 1 d model or by the single sampling point it was shown however that an additional sampling point located outside the area active in water uptake may substantially improve the quantitative description of the response of the complicated 3 d flow system

numerical analyses of subsurface flow in a steep hillslope under rainfall the role of the spatial heterogeneity of the formation hydraulic properties 1 the paper aims at analyzing subsurface flow and streamflow generation in steep hillslopes after rainfall the principal scope of the work is to assess the role played by the spatial variability of the hydraulic properties on the subsurface flow patterns and hillslope discharge we try to address this task through a three dimensional numerical model which solves the richards equation under prescribed initial and boundary conditions along an established practice the relevant hydraulic parameters are modeled as random space functions with given statistical properties realistic features of the spatially variable formation parameters and the precipitation data are incorporated into the simulation model it is found that spatial heterogeneity has a significant impact on the movement of water in the hillslope and the streamflow generation in particular the heterogeneous systems are more sensitive to rain input and display an increase of both the water table and saturation which is faster than the homogeneous case the same is for water velocity which is everywhere larger when heterogeneity is considered as a consequence the dynamics of subsurface stormflow recognized as the leading mechanism for streamflow generation in the simulations and the outflow discharge produced by the hillslope after a rain event are enhanced by heterogeneity despite of the possible lack of generality of the numerical experiments they provide useful insight into the complex dynamics occurring in hillslope systems the simulations show the importance of including realistic spatial heterogeneity in hillslope hydrology studies

coupling of diffusional mass transport and deformation in a tight rock abstract simple governing equations coupling diffusional transport at a macroscopic scale and deformation in a tight rock are formulated the deformation alone is described by a linear viscous rheology several deformations of geological interest are analyzed including the folding of an embedded layer a basic feature is the length scale dependence of diffusional effects interpretation of natural structures permits the estimation of parameters governing the diffusional transport and rate of deformation

seismic migration with inverse q filtering 1 taking account the earth q effect i e frequency dependent amplitude decay and velocity dispersion during seismic migration simultaneously the resultant seismic image is expected to be high resolution with true amplitude and correct timing we present here a stabilized algorithm for such a migration incorporating inverse q filtering scheme so that the imaging technique is applicable to seismographs with long recording time the earth model is assumed to be 1 d with continuous variations vertically in velocity and attenuation and the imaging algorithm is implemented easily and efficiently in the frequency wavenumber domain although such a 1 d model suits mostly to the cases in lithospheric scale regional geophysics it is sometimes also suitable to the exploration seismic studies the method is demonstrated using a real data example from exploration seismics with an attempt to recover a target reflection underneath a group of strong coal seam reflections

efficient 3 d frequency domain mono parameter full waveform inversion of ocean bottom cable data application to valhall in the visco acoustic vertical transverse isotropic approximation computationally efficient 3 d frequency domain full waveform inversion fwi is applied to ocean bottom cable data from the valhall oil field in the visco acoustic vertical transverse isotropic vti approximation frequency domain seismic modelling is performed with a parallel sparse direct solver on a limited number of computer nodes a multiscale imaging is performed by successive inversions of single frequencies in the 3 5 10 hz frequency band the vertical wave speed is updated during fwi while density quality factor qp and anisotropic thomsen s parameters and are kept fixed to their initial values the final fwi model shows the resolution improvement that was achieved compared to the initial model that was built by reflection traveltime tomography this fwi model shows a glacial channel system at 175 m depth the footprint of drifting icebergs on the palaeo seafloor at 500 m depth a detailed view of a gas cloud at 1 km depth and the base cretaceous reflector at 3 5 km depth the relevance of the fwi model is assessed by frequency domain and time domain seismic modelling and source wavelet estimation the agreement between the modelled and recorded data in the frequency domain is excellent up to 10 hz although amplitudes of modelled wavefields propagating across the gas cloud are overestimated this might highlight the footprint of attenuation whose absorption effects are underestimated by the homogeneous background qp model qp 200 the match between recorded and modelled time domain seismograms suggests that the inversion was not significantly hampered by cycle skipping however late arrivals in the synthetic seismograms computed without attenuation and with a source wavelet estimated from short offset early arrivals arrive 40 ms earlier than the recorded seismograms this might result from dispersion effects related to attenuation the repeatability of the source wavelets inferred from data that are weighted by a linear gain with offset is dramatically improved when they are estimated in the fwi model rather than in the smooth initial model the two source wavelets estimated in the fwi model from data with and without offset gain show a 40 ms time shift which is consistent with the previous analysis of the time domain seismograms the computational efficiency of our frequency domain approach is assessed against a recent time domain fwi case study performed in a similar geological environment this analysis highlights the efficiency of the frequency domain approach to process a large number of sources and receivers with limited computational resources thanks to the efficiency of the substitution step performed by the direct solver this efficiency can be further improved by using a block low rank version of the multifrontal solver and by exploiting the sparsity of the source vectors during the substitution step future work will aim to update attenuation and density at the same time of the vertical wave speed

solute transport through a heterogeneous coupled vadose saturated zone system with temporally random rainfall the transport of nonreactive solutes through a coupled two dimensional randomly heterogeneous vadose saturated zone system subject to temporally random rainfall is predicted by monte carlo simulation and compared with previously published analytic results for three different rainfall patterns the relative contributions of the uncertain inputs i e rainfall and saturated conductivity to the prediction uncertainty of solute transport are quantified in terms of the statistical moments of the pore water velocity the plume spatial moments and solute flux breakthrough curves at downstream control planes results show that the mean and variance of the saturated zone pore water velocity were approximately equivalent for the cases of uniform and random rainfall and were well predicted by the analytical relationships developed by rubin and bellin 1994 as a result the mean plume displacement estimated by the trajectory of the mean plume center of mass was found to be nearly identical for these cases in the temporally random rainfall case the saturated zone mean plume experienced more spread in the direction of mean flow at early times however the asymptotic rates of spatial spreading of the mean solute plumes were found to be approximately equivalent for the uniform and random rainfall cases and well predicted by the approximate expressions for longitudinal macrodispersivity in nonuniform flow proposed by destouni and graham 1995 random rainfall and random soil properties increased prediction uncertainty of the solute plume behavior in the vadose zone by an order of magnitude when compared with the uniform rain and random soil case this effect was reduced considerably when the solute entered the saturated zone where random rainfall produced only slightly larger prediction uncertainty than the uniform rainfall case the analytic model developed by destouni and graham 1995 accurately predicted the temporal breakthrough of the mean solute plume at saturated zone control planes for all cases if transport through the unsaturated zone accounted for the effects of temporally random rainfall using the methodology developed by foussereau et al 2000a 2000b results of this work indicate that for the humid climates studied here uncertain rainfall patterns dominate transport prediction uncertainty in the shallow unsaturated zone while uncertain solute breakthrough to the saturated zone and uncertain hydraulic conductivity dominate prediction uncertainty in the saturated zone

a new type of numerical experiment on the spatial and temporal patterns of localization of deformation in a material with a coupling of grain size and rheology abstract the patterns of localization of deformation in recrystallising materials are investigated via a series of two dimensional grain scale numerical simulations these simulations couple a grain size and strain dependant viscous rheology with grain size reduction and grain growth processes the simulations are able to predict the mechanical microstructural and strain evolution of the polycrystals to moderate strain and allow us to examine the nature of the time dependent feedback between mechanical and microstructural behavior it was found that significant strain localization occurred only when the grain size dependence of the viscosity was non linear and was greatly enhanced by the activity of the grain size modifying processes the intensity and location of the zone of strain localization varied spatially and temporally and displayed two length and time scales with the result that the finite strain state showed a much broader and hence less intense zone of localized deformation than the instantaneous state

longitudinal and lateral dispersion in an unsaturated field soil lateral and longitudinal dispersion was quantified in a field soil under water unsaturated conditions the relatively mobile dye tracer brilliant blue fcf was applied as a line source and leached into the soil at two different rates of infiltration 4 and 24 mm d 1 respectively the resulting tracer plume was photographically recorded at vertical soil profiles excavated perpendicularly to the line source after 50 100 and 200 mm of cumulative infiltration an image analysis technique was used to determine two dimensional concentration distributions from the photographs average horizontal and vertical concentration distributions were analyzed using the two dimensional advection dispersipn equation model parameters were fitted to optimize the agreement between measured and modeled averaged concentration profiles in both horizontal as well as vertical directions dispersivities showed a dependency on flow rates and amount of cumulative infiltration but this dependency appeared to be related to the degree of irregularities of observed flow patterns large dispersivities were associated with higher degree of irregularities in the flow patterns and vice versa layer boundaries played a significant role for redirecting flow when flow rates were high and cumulative infiltration was large this study demonstrates 1 that more than just the vertical concentration profiles are needed to define the transport regime under unsaturated conditions and 2 that even subtle layer boundaries affect the lateral mixing regime and exert a marked influence on the transport in the main flow direction

finite element modelling of the evolution of pressure solution cleavage abstract deformation by pressure solution or water assisted stress induced diffusion transfer is modelled by incorporating volume transfers driven by variations in mean stress and competency contrast into a finite element code for viscous deformation the model assumes a two component quartz mica mixture with a composition dependent rheology in which the viscosity of an element is solely dependent upon the volume fraction of the mobile quartz component both quartz rich and mica rich compositions are given a high competency with a minimum viscosity at some intermediate fraction the model is able to reproduce many structures observed in natural tectonites propagation and coalescence of pressure solution seams formation of microlithons and anastomosing cleavage and more generally tectonic segregation

stochastic analysis of simulated vadose zone solute transport in a vertical cross section of heterogeneous soil during nonsteady water flow the problem of transport of a conservative nonreactive solute in a vertical cross section of a hypothetical partially saturated scale heterogeneous soil under transient water flow was analyzed here it was assumed that locally the water flow and the solute transport can be described by the richards equation and by the one component convection dispersion equation respectively the simulated water content and the solute concentration distributions in the vertical cross section of the soil at different elapsed times were quantified in terms of space averages and two point autocorrelation functions the time evolution of the solute plume was quantified in terms of its first two normalized spatial moments from which the time dependence of the longitudinal and the transverse components of the solute velocity vector and the spatial covariance tensor were estimated the results of this study which are relevant to solute transport at the local or the plume scale demonstrated the considerable variability in the solute concentration in space and time due to the complex heterogeneity of the soil hydraulic properties in both the vertical and the horizontal directions consequently the movement of the solute plume was characterized by a compression expansion phenomenon attributed to the decrease in the effective solute velocity through the zones of relatively fine textured soil material it was concluded that existing stochastic vadose zone transport models may be applicable to shallow depths but may fail to describe the actual spread of a solute plume when the transport takes place at relatively large depths mainly because of the neglect of the significant vertical heterogeneity in the soil hydraulic properties

power law catchment scale recessions arising from heterogeneous linear small scale dynamics 1 power law recession behavior has typically been attributed to the hydraulics of subsurface flows in the landscape e g the boussinesq equation many catchments exhibit enormous heterogeneity in their characteristics such as the permeability of soils hillslope length and gradient and soil mantle thickness in the paper we demonstrate using a simple linear flow model that the between hillslope heterogeneity alone can give rise to observed apparently nonlinear recession slope curves the degree of nonlinearity represented by the exponent fitted to the recession slope curve is shown to increase with the degree of heterogeneity of catchment hydraulic properties in sufficiently heterogeneous catchments the recession is also sensitive to the history of recharge events tending to increase when the past events have built up a storage of water in the slow parts of the catchment the models based on the catchment heterogeneity were fitted to data from the panola mountain research watershed yielding a good fit and allowing us to infer how the heterogeneity in catchment properties varies with scale the range of exponents explained by this theory overlaps with the range explained by the hydraulics of subsurface flow which raises doubts about our ability to extract catchment hydraulic parameters on the basis of recession curves so long as the heterogeneity is not accounted for in general the results presented here have enabled us to show how the heterogeneity of landscape characteristics is upscaled and manifested in the apparent nonlinear relationship at the catchment scale

variability of gardner s α for coarse textured sediments vadose zone soils in arid regions often contain a high gravel fraction 2 mm size this paper examines for coarse textured soils variability of the slope of gardner s 1958 unsaturated hydraulic conductivity k versus matric potential relation k kse the steady state head control method was used to obtain unsaturated k for tensions as high as 386 cm a total of 79 samples were analyzed in the laboratory the gravel fraction for the 41 gravelly samples ranged from 20 to 71 by weight the remaining 38 samples were sandy with no gravel fraction the measured k values for the gravelly samples fall within a narrow range and are well within the range of measured k values for the sandy samples the bulk of both gravelly and sandy samples can be described using a single slope exponential model gardner s and the intercept k0 are based on a least squares fit to the late time measurements at lower the mean and variance of for the gravelly samples are lower compared with the sandy type the values for the gravelly soils follow a normal distribution whereas the k0 estimates and the laboratory measured ks follow lognormal distributions for the sandy type k0 and ks follow lognormal distributions the values appear to be related to the median particle diameter d50 and the slope of the particle size distribution a clear reduction in variability of is apparent with an increase in d50 suggesting that the unsaturated k and variability for the gravelly soils can be estimated within narrow ranges the flow weighted characteristic pore size m is clearly dependent on the soil type m values for the gravelly soils are characterized by a smaller mean and variance than for the sandy type this helps explain the finding that the range in unsaturated k for the gravelly soils is less than for the sandy type at higher tensions the mean and variance of and lnk0 as well as the cross correlation between and lnk0 are important inputs to stochastic models of unsaturated flow the implications of their variability on flow in heterogeneous media are discussed

hydrologic response of catchments to precipitation quantification of mechanical carriers and origins of water 1 precipitation induced overland and groundwater flow and mixing processes are quantified to analyze the temporal event and pre event water and spatial groundwater discharge and overland runoff origins of water entering a stream using a distributed parameter control volume finite element simulator that can simultaneously solve the fully coupled partial differential equations describing 2 d manning and 3 d darcian flow and advective dispersive transport mechanical flow driven by hydraulic potential and tracer based hydrograph separation driven by dispersive mixing as well as mechanical flow are simulated in response to precipitation events in two cross sections oriented parallel and perpendicular to a stream the results indicate that as precipitation becomes more intense the subsurface mechanical flow contributions tend to become less significant relative to the total pre event stream discharge hydrodynamic mixing can play an important role in enhancing pre event tracer signals in the stream this implies that temporally tagged chemical signals introduced into surface subsurface flow systems from precipitation may not be strong enough to detect the changes in the subsurface flow system it is concluded that diffusive dispersive mixing capillary fringe groundwater ridging and macropore flow can influence the temporal sources of water in the stream but any sole mechanism may not fully explain the strong pre event water discharge further investigations of the influence of heterogeneity residence time geomorphology and root zone processes are required to confirm the conclusions of this study

prestack depth migration with compensation for absorption and dispersion in prestack depth migration using explicit extrapolators the attenuation and dispersion of the seismic wave has been neglected so far we present a method for accommodating absorption and dispersion effects in depth migration schemes extrapolation operators that compensate for absorption and dispersion are designed using an optimization algorithm the design criterion is that the wavenumber response of the operator should equal the true extrapolator both phase velocity and absorption macro models are used in the wavefield extrapolation in a model with medium to high absorption the images obtained are superior to those obtained using extrapolators without compensation for absorption

seismic attenuation tomography using the frequency shift method we present a method for estimating seismic attenuation based on frequency shift data in most natural materials seismic attenuation increases with frequency the high frequency components of the seismic signal are attenuated more rapidly than the low frequency components as waves propagate as a result the centroid of the signal s spectrum experiences a downshift during propagation under the assumption of a frequency independent q model this downshift is proportional to a path integral through the attenuation distribution and can be used as observed data to reconstruct the attenuation distribution tomographically the frequency shift method is applicable in any seismic survey geometry where the signal bandwidth is broad enough and the attenuation is high enough to cause noticeable losses of high frequencies during propagation in comparison to some other methods of estimating attenuation our frequency shift method is relatively insensitive to geometric spreading reflection and transmission effects source and receiver coupling and radiation patterns and instrument responses tests of crosswell attenuation tomography on 1 d and 2 d geological structures are presented

primary structure influence on compositional banding in psammites examples from the puncoviscana formation north central argentina abstract we investigate the influence of sedimentary structures in development of foliations in banded psammites and pelites in the meta turbiditic pampean belt eastern sierras pampeanas northwest argentina these anchizone to upper greenschist facies rocks were exhumed from near surface to mid crustal levels and preserve sedimentary structures and gradual changes in tectonic fabrics and microstructures primary variations in clay content affected the degree of development of a compaction related pressure solution cleavage s p resulting in enhancement of the original sedimentary banding the resulting compositional banding was overprinted by a tectonic cleavage s 1 related to mid cambrian chevron folding in banded sandstones pressure solution and mica growth that define s p and s 1 foliations are increasingly better developed in phyllosilicate rich domains with increasing structural depth and metamorphic grade clay rich laminae in the protolith acted as the locus for mica nucleation and growth favoring dissolution of quartz up to 42 causing passive concentration of mica pressure solution thus produced banded sandstones with a spaced bedding parallel s p cleavage in shallower sections and compositionally banded psammites and schists at depth these observations demonstrate that formation of compositional banding does not require tectonic transposition of an older planar fabric similar processes may produce compositional banding in a wide range of meta sedimentary rocks

effect of pulse release date and soil characteristics on solute transport in a combined vadose zone groundwater flow system insights from numerical simulations 1 the transport of a conservative tracer bromide in a three dimensional heterogeneous combined vadose zone groundwater flow system was analyzed through a series of detailed numerical simulations the scope of the present study was to analyze the effect of both the soil type and the pulse application date on solute movement and spreading in the combined flow system subject to time dependent external forcing conditions f t characterized by a time period imposed on a flat soil surface of particular interest were the suitability of the time invariance assumption of the solute travel time distribution and the related issue of the capability of an equivalent steady state vadose zone flow model to describe solute transport in a realistic flow system considering flow systems in which the water table is located at sufficiently large distance from the flat soil surface the main results of this study suggest that the velocity associated with the wetting front position which may be considered as an effective velocity is soil and calendar date dependent consequently characteristics of the transport i e solute displacement and spreading first and peak arrival times are soil and pulse release date dependent the soil dependent solute travel time pdf at a cp located in the vicinity of the water table however may be considered as essentially independent of the pulse release date particularly in the fine textured clay soil associated with mean travel time that substantially exceeds furthermore for the equivalent steady state definition of the flow problem may be quite effective in describing the solute travel time pdf of the actual transport process occurring under nonmonotonous transient flow conditions

compaction of porous rock by dissolution on discrete stylolites a one dimensional model 1 compaction of sedimentary porous rock by dissolution and precipitation is a complex deformation mechanism that is often localized on stylolites and pressure solution seams we consider a one dimensional model of compaction near a thin clay rich stylolite embedded in a porous rock under the assumption that the clay enhances solubility the model predicts a reactive transport away from the clay layer followed by pore cementation the evolution of the porosity reactant transport and compaction rate are studied as functions of model parameters and shown to reach a stationary state we find good agreement between the porosity distribution predicted by the model and previously reported field measurements the model provides quantitative estimates for compaction rates on stylolitic surfaces

full waveform inversion and distance separated simultaneous sweeping a study with a land seismic data set abstract dense wide aperture and broad frequency band acquisition improves seismic imaging and potentially allows the use of full waveform inversion for velocity model building the cost of dense acquisitions however limits its applicability blended or simultaneous shooting could lead to a good compromise between cost and dense acquisition although the cross talk between simultaneous sweeps may reduce imaging capabilities onshore a compromise is achieved with distance separated simultaneous sweeping acquisition because the shots are easily separated when the processing focuses on pre critical reflected events full waveform inversion for velocity model building however relies on post critical reflected refracted and diving events these events can interfere in a distance separated simultaneous sweeping acquisition by using a single vibrator single receiver data set recorded in inner mongolia china a distance separated simultaneous sweeping data set is created to study the robustness of full waveform inversion in this acquisition context this data set is well suited for full waveform inversion since it contains frequencies down to 1 5 hz and offsets up to 25 km full waveform inversion after a crude deblending of the distance separated simultaneous sweeping data set leads to a result very similar to the one obtained from the single vibrator single receiver data set the inversion of the blended data set gives a slightly less good result because of the cross talk but it is still quite satisfactory

inverse theory applied to multi source cross hole tomography part 1 acoustic wave equation method1 frequency domain methods are well suited to the imaging of wide aperture cross hole data however although the combination of the frequency domain with the wavenumber domain has facilitated the development of rapid algorithms such as diffraction tomography this has also required linearization with respect to homogeneous reference media this restriction and association restrictions on source receiver geometries are overcome by applying inverse techniques that operate in the frequency space domain in order to incorporate the rigorous modelling technique of finite differences into the inverse procedure a nonlinear approach is used to reduce computational costs the method of finite differences is applied directly to the frequency domain wave equation the use of high speed high capacity vector computers allow the resultant finite difference equations to be factored in place in this way wavefields can be computed for additional source positions at minimal extra cost allowing inversions to be generated using data from a very large number of source positions synthetic studies show that where weak scatter approximations are valid diffraction tomography performs slightly better than a single iteration of non linear inversion however if the background velocities increase systematically with depth diffraction tomography is ineffective whereas non linear inversion yields useful images from one frequency component of the data after a single iteration further synthetic studies indicate the efficacy of the method in the time lapse monitoring of injection fluids in tertiary hydrocarbon recovery projects

stylolites a review abstract stylolites are ubiquitous geo patterns observed in rocks in the upper crust from geological reservoirs in sedimentary rocks to deformation zones in folds faults and shear zones these rough surfaces play a major role in the dissolution of rocks around stressed contacts the transport of dissolved material and the precipitation in surrounding pores consequently they play an active role in the evolution of rock microstructures and rheological properties in the earth s crust they are observed individually or in networks in proximity to fractures and joints and in numerous geological settings this review article deals with their geometrical and compositional characteristics and the factors leading to their genesis the main questions this review focuses on are the following how do they form how can they be used to measure strain and formation stress how do they control fluid flow in the upper crust geometrically stylolites have fractal roughness with fractal geometrical properties exhibiting typically three scaling regimes a self affine scaling with hurst exponent 1 1 0 1 at small scale up to tens or hundreds of microns another one with hurst exponent around 0 5 to 0 6 at intermediate scale up to millimeters or centimeters and in the case of sedimentary stylolites a flat scaling at large scale more complicated anisotropic scaling scaling laws depending of the direction of the profile considered is found in the case of tectonic stylolites we report models based on first principles from physical chemistry and statistical physics including a mechanical component for the free energy associated with stress concentrations and a precise tracking of the influence of grain scale heterogeneities and disorder on the resulting micro structures experimental efforts to reproduce stylolites in the laboratory are also reviewed we show that although micrometer size stylolite teeth are obtained in laboratory experiments teeth deforming numerous grains have not yet been obtained experimentally which is understandable given the very long formation time of such geometries finally the applications of stylolites as strain and stress markers to determine paleostress magnitude are reviewed we show that the scalings in stylolite heights and the crossover scale between these scalings can be used to determine the stress magnitude its scalar value perpendicular to the stylolite surface during the stylolite formation and that the stress anisotropy in the stylolite plane can be determined for the case of tectonic stylolites we also show that the crossover between medium millimetric scales and large pluricentimetric scales in the case of sedimentary stylolites provides a good marker for the total amount of dissolution which is still valid even when the largest teeth start to dissolve which leads to the loss of information since the total deformation is not anymore recorded in a single marker structure we discuss the impact of the stylolites on the evolution of the transport properties of the hosting rock and show that they promote a permeability increase parallel to the stylolites whereas their effect on the permeability transverse to the stylolite can be negligible or may reduce the permeability depending on the development of the stylolite

upper bound on stylolite roughness as indicator for amount of dissolution stylolites are rough surfaces that form by localized dissolution despite their abundance in carbonates and sandstones and their importance for fluid flow and rock deformation many fundamental issues concerning their structure and evolution are still unresolved this manuscript studies the roughening of long parallel stylolites here we report measurements of stylolite surface roughness at a scale larger than ever measured before 10 2 10 1 m measurements were performed using ground based lidar on 6 naturally exposed surfaces of 4 km long stylolites in northern israel producing a topographic map of the surfaces from which roughness characteristics were derived our results show that for length scales below 50 cm the stylolite morphology exhibits self affine behavior with a hurst exponent h 0 65 consistent with previous studies made on smaller samples the self affine behavior changes for measurements made on scales above 50 cm with h decreasing almost to zero on long length scales this observed upper bound of self affine roughness is measured here for the first time but has been previously predicted by theory ebner et al 2009b koehn et al 2007 our measurements support these theoretical models and together with them present a scenario in which the investigated stylolites evolve from preferential dissolution along an existing surface that was initially smooth and progressively roughened with time such a mechanism of stylolites growth is different from previously suggested mechanisms for other classes of stylolites which might propagate sideways from an initial defect based on the theoretical roughening model that we adopted the upper limit to fractality for this class of stylolites may be used as a measure of the amount of dissolution on stylolites indeed the amount of dissolution on the stylolites in our field site which we calculated from the upper limit to fractality is comparable to though slightly larger than our estimates of dissolution from two additional independent techniques reflecting compactive strain of 50

two dimensional velocity models from wide angle seismic data by wavefield inversion summary modern wide angle surveys are often multi fold and multi channel with densely sampled source and receiver spacings such closely spaced data are potentially amenable to multi channel techniques involving wavefield propagation methods such as those commonly used in reflection data processing however the wide angle configuration requires techniques capable of handling very general wave types including those not commonly used in reflection seismology this is a situation analogous to that faced in cross borehole seismics where similar wave types are also recorded in a real cross borehole example we compare pre stack migration traveltime tomography and wavefield inversion we find that wavefield inversion produces images that are quantitative in velocity as are the tomograms but are of significantly higher resolution the wavefield inversion results have a resolution comparable to that of the qualitative pre stack migration images we seek to extend this novel development to the larger scale problem of crustal imaging an essential element of the approach we adopt is its formulation entirely within the temporal frequency domain this has three principal advantages 1 we can choose to decimate the data by selecting only a limited number of frequency components to invert thus making inversion of data from large numbers of source positions feasible 2 we can mitigate the notorious non linearity of the seismic inverse problem by progressing from low frequency components in the data to high frequency components and 3 we can include in the model any arbitrary frequency dependence of inelastic attenuation factors q and indeed solve for the spatial distribution of q an initial synthetic test with an anomaly located within the middle crust yields a velocity image with the correct structural features of the anomaly and the correct magnitude of velocity anomaly this is related to the fact that the reconstruction is obtained from forward scattered waves under these conditions the method thus behaves much like tomography a second test with a deeper more extensive anomaly yields an image with the correct velocity polarity and the correct location but with a deficiency in low and high wavenumbers in this case this is because the reconstruction is obtained from backscattered waves under these conditions the method behaves not like tomography but like migration a more extensive test based on a large wide angle survey in south eastern california and western arizona demonstrates a real potential for high resolution imaging of crustal structures although our results are limited by the acoustic approximation and by the relatively low frequencies that we can model today the images are sufficiently encouraging to warrant future research the problem of local minima in the objective function is the most significant practical problem with our method but we propose that appropriate layer stripping methods can handle this problem

investigating the use of 3 d full waveform inversion to characterize the host rock at a geological disposal site the u k government has a policy to dispose of higher activity radioactive waste in a geological disposal facility gdf which will have multiple protective barriers to keep the waste isolated and to ensure no harmful quantities of radioactivity are able to reach the surface currently no specific gdf site in the united kingdom has been chosen but once it has the site is likely to be investigated using seismic methods in this study we explore whether 3 d full waveform inversion fwi of seismic data can be used to map changes in physical properties caused by the construction of the site specifically tunnel induced fracturing we have built a synthetic model for a gdf located in granite at 1000 m depth below the surface since granite is one of the candidate host rocks due to its high strength and low permeability and the gdf could be located at such a depth we use an effective medium model to predict changes in p wave velocity associated with tunnel induced fracturing within the spatial limits of an excavated disturbed zone edz modelled here as an increase in fracture density around the tunnel we then generate synthetic seismic data using a number of different experimental geometries to investigate how they affect the performance of fwi in recovering subsurface p wave velocity structure we find that the location and velocity of the edz are recovered well especially when data recorded on tunnel receivers are included in the inversion our findings show that 3 d fwi could be a useful tool for characterizing the subsurface and changes in fracture properties caused during construction and make a suite of suggestions on how to proceed once a potential gdf site has been identified and the geological setting is known

multiparameter full waveform inversion of multicomponent ocean bottom cable data from the valhall field part 1 imaging compressional wave speed density and attenuation multiparameter full waveform inversion fwi is a challenging quantitative seismic imaging method for lithological characterization and reservoir monitoring the difficulties in multiparameter fwi arise from the variable influence of the different parameter classes on the phase and amplitude of the data and the trade off between these in this framework choosing a suitable parametrization of the subsurface and designing the suitable fwi workflow are two key methodological issues in non linear waveform inversion we assess frequency domain visco acoustic fwi to reconstruct the compressive velocity vp the density or the impedance ip and the quality factor qp from the hydrophone component using a synthetic data set that is representative of the valhall oil field in the north sea we first assess which of the vp and vp ip parametrizations provides the most reliable fwi results when dealing with wide aperture data contrary to widely accepted ideas we show that the vp parametrization allows a better reconstruction of both the vp and ip parameters first because it favours the broad band reconstruction of the dominant vp parameter and secondly because the trade off effects between velocity and density at short to intermediate scattering angles can be removed by multiplication to build an impedance model this allows for the matching of the reflection amplitudes while the broad band velocity model accurately describes the kinematic attributes of both the diving waves and reflections then we assess different inversion strategies to recover the quality factor qp in addition to parameters vp and a difficulty related to attenuation estimation arises because on the one hand the values of qp are on average one order of magnitude smaller than those of vp and and on the other hands model perturbations relative to the starting models can be much higher for qp than for vp and during fwi in this framework we show that an empirical tuning of the fwi regularization which is adapted to each parameter class is a key issue to correctly account for the attenuation in the inversion we promote a hierarchical approach where the dominant parameter vp is reconstructed first from the full data set i e without any data preconditioning to build a velocity model as kinematically accurate as possible before performing the joint update of the three parameter classes during a second step this hierarchical imaging of compressive wave speed density and attenuation is applied to a real wide aperture ocean bottom cable data set from the valhall oil field several geological features such as accumulation of gas below barriers of claystone and soft quaternary sediment are interpreted in the fwi models of density and attenuation the models of vp and qp that have been developed by visco acoustic fwi of the hydrophone data can be used as initial models to perform visco elastic fwi of the geophone data for the joint update of the compressive and shear wave speeds

rock matrix structures in a zone influenced by a stylolite abstract a stylolitic structure is one of the visible manifestations of the pressure solution process in a rock the stylolitic process zone as defined in previous studies on both sides of a stylolite is studied by sem the chosen samples concern tectonic stylolites within a high porosity limestone 16 without tension gashes this zone corresponds to a local increase of porosity and comprises a large number of stylolitic joints showing a decreasing size from the macroscopic structure to simple contact between two grains two hypotheses are presented for the stylolite formation 1 the macroscopic stylolite is the result of the coalescence of earlier minor pressure solution structures 2 small stylolites nucleate gradually from a major stylolite joint the mass transfer can be realized either by diffusion between particles or by seepage through previously undescribed process zone fractures the mass deposition can be localized in the porous volume and the microcracks without requiring any additional tectonic openings including tension gashes the rock deformation is therefore limited to shortening parallel to 1 without normal extension

temporal scaling of groundwater discharge in dual and multicontinuum catchment models this paper presents a multicontinuum approach to model fractal temporal scaling of catchment response in hydrological systems the temporal scaling of discharge is quantified in frequency domain by the transfer function h x which is defined as the ratio between the spectra of catchment response and recharge time series the transfer function may scale with frequency x as h x x2b while the classical linear and dupuit models predict exponents of b52 and b51 observations indicate scalings with noninteger exponents b such behaviors have been described by multifractal models which however often lack a relation to the medium characteristics we revisit and extend the classical linear dupuit aquifer models and discuss their physical meanings in the light of the resulting aquifer dynamics on the basis of these classical models we derive a multicontinuum approach that provides physical recharge models which are able to explain fractal behaviors with exponents 1 2 b 2 furthermore this approach allows to link the fractal dynamics of the discharge process to the physical aquifer characteristics as reflected in the distribution of storage time scales we systematically analyze the catchment responses in the proposed multicontinuum models and identify and quantify the time scales which characterize the dynamics of the catchment response to recharge

stochastic analysis of transport in hillslopes travel time distribution and source zone dispersion 1 a stochastic model is developed for the analysis of the traveltime distribution f in a hillslope the latter is described as made up from a surficial soil underlain by a less permeable subsoil or bedrock the heterogeneous hydraulic conductivity k is described as a stationary random space function and the model is based on the lagrangian representation of transport a first order approach in the log conductivity variance is adopted in order to get closed form solutions for the principal statistical moments of the traveltime our analysis indicates that the soil is mainly responsible for the early branch of f i e the rapid release of solute which preferentially moves through the upper soil the early branch of f is a power law with exponent variable between 1 and 0 5 the behavior is mainly determined by unsaturated transport the subsoil response is slower than that of the soil the subsoil is mainly responsible for the tail of f which in many cases resembles the classic linear reservoir model the resulting shape for f is similar to the gamma distribution analysis of the f moments indicates that the mean traveltime is weakly dependent on the hillslope size the traveltime variance is ruled by the distribution of distances of the injected solute from the river the effect is coined as source zone dispersion the spreading due to the k heterogeneity is less important and obscured by source zone dispersion the model is tested against the numerical simulation of fiori and russo 2008 with reasonably good agreement with no fitting procedure

effects of hydraulic conductivity variability on hillslope scale shallow subsurface flow response and storage discharge relations 1 an important problem in scientific hydrology is accounting for the effect of small scale heterogeneity in lumped representations of flow through landscapes in this work we investigate the effect of lateral variations in hydraulic conductivity on saturated subsurface lateral flow through hillslopes using an idealized model based on the boussinesq equation the model simulates flow over an impervious planar base through heterogeneous conductivity fields in response to simple recharge inputs and periodic recharge events the results indicate that the hillslope scale response depends on the relative importance of topographic and water table potential gradients driving flow the relative magnitude of these drivers is related to a dimensionless variable where water table gradients dominate a network of flow paths channel flow through the hillslope toward high conductivity areas and the response is primarily dependent on the boundary condition at the toe of the hillslope where the topographic gradients dominate the flow is delayed by low conductivity areas producing a power law like response suggesting that high exponents in observed storage discharge relations may be traced to the presence of heterogeneity in the landscape these observations suggest that the nature of the lumped hillslope scale hydrologic models depends on the emergent behaviors that arise at that scale as a result of the interactions between hillslope properties including their variability in space the relationship between the hillslopes and their surrounding landscape elements through the boundary conditions and the temporal variability of the recharge that enters the system

large scale natural gradient tracer test in sand and gravel cape cod massachusetts 3 hydraulic conductivity variability and calculated macrodispersivities hydraulic conductivity k variability in a sand and gravel aquifer on cape cod massachusetts was measured and subsequently used in stochastic transport theories to estimate macrodispersivities nearly 1500 k measurements were obtained by borehole flowmeter tests and permeameter analyses of cores the geometric mean for the flowmeter tests 0 11 cm s is similar to that estimated from other field tests the mean for the permeameter tests 0 035 cm s is significantly lower possibly because of compaction of the cores the variance for the flowmeter 0 24 is also greater than that for the permeameter 0 14 geostatistical analyses applying negative exponential models with and without nuggets reveal similar spatial correlation structures for the two data sets estimated correlation scales range from 2 9 to 8 m in the horizontal and from 0 18 to 0 38 m in the vertical estimates of asymptotic longitudinal dispersivity b 35 0 78 m are similar in magnitude to that observed in the natural gradient tracer test 0 96 m previously conducted at this site

finite element modelling of the propagation of a pressure solution cleavage seam abstract the propagation of a cleavage seam is modelled by a two dimensional finite element technique which extends fletcher and pollard s elastic anticrack theory to a composition dependent viscous rheology the viscous solution is obtained by repeated solutions of the force equilibrium equations at successive time steps with the viscosity of each element varying as a function of its strain history the rheology assumed follows previous modelling by robin the rock is modelled as a quartz mica mixture in which deformation proceeds by diffusion of silica the viscosity of an element depends on its proportion of quartz varying from a minimum for intermediate quartz mica mixtures to higher values for either pure quartz or pure micas as a result of its incremental strain an element either loses or gains quartz i e volume and therefore changes its viscosity for the next strain increment the system can be either open silica escapes the system all individual elements lose volume or closed individual elements may gain or lose volume but the total volume of the system is preserved at the start of a run a nucleus of a cleavage seam is introduced as a thin layer of elements with a lower viscosity corresponding to a higher mica content than the rest of the rock the stress concentration at the tip of the seam leads to a weakening of the elements in front of it through loss of quartz this results in crack propagation for both open and closed systems all other parameters being equal the speed of propagation is greater for open systems than for closed ones

gypsies in the palace experimentalist s view on the use of 3 d physics based simulation of hillslope hydrological response as a fundamental unit of the landscape hillslopes are studied for their retention and release of water and nutrients across a wide range of ecosystems the understanding of these near surface processes is relevant to issues of runoff generation groundwater surface water interactions catchment export of nutrients dissolved organic carbon contaminants e g mercury and ultimately surface water health we develop a 3 d physics based representation of the panola mountain research watershed experimental hillslope using the tough2 sub surface flow and transport simulator a recent investigation of sub surface flow within this experimental hillslope has generated important knowledge of threshold rainfall runoff response and its relation to patterns of transient water table development this work has identified components of the 3 d sub surface such as bedrock topography that contribute to changing connectivity in saturated zones and the generation of sub surface stormflow here we test the ability of a 3 d hillslope model both calibrated and uncalibrated to simulate forested hillslope rainfall runoff response and internal transient sub surface stormflow dynamics we also provide a transparent illustration of physics based model development issues of parameterization examples of model rejection and usefulness of data types e g runoff mean soil moisture and transient water table depth to the model enterprise our simulations show the inability of an uncalibrated model based on laboratory and field characterization of soil properties and topography to successfully simulate the integrated hydrological response or the distributed water table within the soil profile although not an uncommon result the failure of the field based characterized model to represent system behaviour is an important challenge that continues to vex scientists at many scales we focus our attention particularly on examining the influence of bedrock permeability soil anisotropy and drainable porosity on the development of patterns of transient groundwater and sub surface flow internal dynamics of transient water table development prove to be essential in determining appropriate model parameterization copyright 2010 john wiley sons ltd

dissecting the variable source area concept subsurface flow pathways and water mixing processes in a hillslope summary this study uses an instrumented trenched 0 5 ha hillslope in the southern tier of new york state usa to provide new data and insights on how variable source areas and associated flow pathways form and combine to connect rainfall with downstream water flows across a hillslope measurements of water fluxes in the trench upslope water table dynamics surface and bedrock topography and isotopic and geochemical tracers have been combined for a four dimensional space time characterization of subsurface storm flow responses during events with dry antecedent conditions infiltrating rainwater was found to percolate through a prevailing fragipan layer to deeper soil layers with much 33 71 of the total discharge of the hillslope originating from deeper water flow below the fragipan during storm events with wet antecedent conditions and large rainfall amounts shallow lateral flow of event and pre event water above the fragipan occurred and was one magnitude greater than the deeper water flow contribution spatial surface and subsurface water quality observations indicate that water from a distance of up to 56 m contributed runoff from the hillslope during storm events in addition mobilization of total dissolved phosphorus tdp with subsurface flow played a greater role than with overland or near surface flow during all events tdp loads were highest in the total discharge during peak flows 8 11 5 kg ha 1 d 1 except during the largest storm event when tdp concentrations were highly diluted these results have implications for strategies to protect streams and other downstream water recipients from waterborne nutrient and pollutant loading

using the continuum approach to model unsaturated flow in fractured rock the appropriateness of using the continuum approach for simulations of unsaturated flow through fractured rock is examined in a numerical study of water seepage into an underground opening a continuum model is calibrated against data generated with a high resolution model that created discrete flow and seepage behavior probabilistic predictions of injection data and seepage rates are then compared to the values from the discrete model the study shows that reasonable results can be obtained with a calibrated continuum model even for fractured systems in which the underlying flow processes are discrete calibration is a crucial step in this approach because it yields effective model related and process specific parameters the impact of discretization on the estimated parameters is discussed prediction uncertainty is evaluated by means of monte carlo simulations including both the impact of parameter uncertainties and the effect of local heterogeneity in this paper the advantages and limitations of the continuum approach are discussed from a practical perspective which includes a critical examination of project objectives data needs robustness of assumptions and prediction uncertainty

a subordinated kinematic wave equation for heavy tailed flow responses from heterogeneous hillslopes 1 analytical expressions of hillslope scale subsurface stormflow discharge are currently restricted to hillslopes with homogeneous or mildly heterogeneous conductivity fields in steep straight hillslopes with uniform recharge these exhibit a classical piston flow response which arises from an assemblage of impulses all moving at a constant velocity but with different starting locations heterogeneity within a hillslope soil creates variations in the downslope velocity of these impulses which may lead to nonpiston flow responses with either exponential or heavy power law tails the presence of heavy tails suggests that heterogeneity imparts a temporal memory on the motion of the impulses using this assumption a subordinated kinematic wave equation is proposed for moderately to highly heterogeneous hillslopes this equation convolves the piston response from a homogenous hillslope with a stable subordinator the stable subordinator randomizes the time that impulses spend in motion and produces nonpiston solutions with heavy tails through comparisons of synthetic data generated from numerical hillslope simulations with physically realistic parameters this equation faithfully reproduces both early and late time characteristics of heavy tailed flow responses from moderate to highly heterogenous hillslopes a systematic evaluation of hillslope responses under different degrees of heterogeneity revealed a quantitative link between the statistical properties of the heterogeneous random fields and the parameters of the subordination framework this suggests that the subordinator can be parameterized with the physical measurement of hillslope properties

unsaturated flow in spatially variable fields 1 derivation of models of infiltration and redistribution models of water flow in the upper soil layer of spatially variable fields are developed field variability is assumed to take place in the horizontal plane the saturated hydraulic conductivity is assumed to be a random variable of lognormal distribution and head suction and moisture content are related to it by simple analytical relationships the aim of the study is to derive the expectation and variances of the moisture content suction heads hydraulic conductivity and water flux as functions of depth and time for infiltration and redistribution toward this aim a simplified solution of vertical flow in a homogeneous column based on the concept of moving front is developed the statistical procedure for using this solution in a spatially variable field is outlined