stress and earthquakes in southern california 1850 2004 1 we compute the stress tensor in the upper crust of southern california as a function of time and compare observed seismicity with the estimated stress at the time of each earthquake several recent developments make it possible to do this much more realistically than before 1 a wealth of new geodetic and geologic data for southern california and 2 a catalog of moment tensors for all earthquakes with magnitudes larger than 6 since 1850 and larger than 5 since 1910 we model crustal deformation using both updated geodetic data and geologically determined fault slip rates we subdivide the crust into elastic blocks delineated by faults which move freely at a constant rate below a locking depth with a rate determined by the relative block motion we compute normal and shear stresses on nodal planes for each earthquake in the catalog we consider stress increments from previous earthquakes seismic stress and aseismic tectonic stress both separately and in combination the locations and mechanisms of earthquakes are best correlated with the aseismic shear stress including the cumulative coseismic effects from past earthquakes does not significantly improve the correlation correlations between normal stress and earthquakes are always very sensitive to the start date of the catalog whether we exclude earthquakes very close to others and whether we evaluate stress at the hypocenter or throughout the rupture surface of an earthquake although the correlation of tectonic stress with earthquake triggering is robust other results are unstable apparently because the catalog has so few earthquakes

characterization and scaling of mesoscale heterogeneities in sandstones 1 a core flooding technique to measure core and subcore scale capillary pressure curves is applied to the characterization of a naturally heterogeneous sandstone core n2 and water are used as the nonwetting and wetting fluid phases and x ray imaging is applied to precisely visualize multiphase flow at the subcentimeter scale the spatial variability in the pc s relationship is represented in terms of scaling factors which are further translated into a corresponding distribution of permeabilities thus creating a unique and consistent framework where multiphase and rock properties are integrated the analysis introduced here provides a practical and efficient method for characterizing subcore scale heterogeneities whose effects can be substantial on both single and multiphase flows

seismic gaps and earthquakes 1 mccann et al 1979 published a widely cited seismic gap model ascribing earthquake potential categories to 125 zones surrounding the pacific rim nishenko 1991 published an updated and revised version including probability estimates of characteristic earthquakes with specified magnitudes within each zone these forecasts are now more than 20 and 10 years old respectively and sufficient data now exist to test them rather conclusively for the mccann et al forecast we count the number of qualifying earthquakes in the several categories of zones we assume a hypothetical probability consistent with the gap model e g red zones have twice the probability of green zones and test against the null hypothesis that all zones have equal probability the gap hypothesis can be rejected at a high confidence level contrary to the forecast of mccann et al the data suggest that the real seismic potential is lower in the gaps than in other segments and plate boundary zones are not made safer by recent earthquakes for the 1991 nishenko hypothesis we test the number of filled zones the likelihood scores of the observed and simulated catalogs and the likelihood ratio of the gap hypothesis to a poissonian null hypothesis for earthquakes equal to or larger than the characteristic magnitude the new seismic gap hypothesis failed at the 95 confidence level in both the number and ratio tests if we lower the magnitude threshold by 0 5 for qualifying earthquakes the new gap hypothesis passes the number test but fails in both the likelihood and likelihood ratio tests at the 95 confidence level

importance of small earthquakes for stress transfers and earthquake triggering 1 we estimate the relative importance of small and large earthquakes for static stress changes and for earthquake triggering assuming that earthquakes are triggered by static stress changes and that earthquakes are located on a fractal network of dimension d this model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other earthquakes increase with m as similar to 10 dm 2 the stronger the spatial clustering the larger the influence of small earthquakes on stress changes at the location of a future event as well as earthquake triggering if earthquake magnitudes follow the gutenberg richter law with b d 2 small earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential using a southern california catalog we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10 alpha m where alpha 1 05 0 05 we also find that the magnitude distribution of triggered earthquakes is independent of the triggering earthquake s magnitude m when alpha approximate to b small earthquakes are roughly as important to earthquake triggering as larger ones we evaluate the fractal correlation dimension d of hypocenters using two relocated catalogs for southern california the value of d measured for distances 0 1 r 5 km is d 1 54 for the shearer et al catalog and d 1 73 for the hauksson et al catalog the value of d reflects both the structure of the fault network and the nature of earthquake interactions by considering only those earthquake pairs with interevent times larger than 1000 days we can largely remove the effects of short term clustering then d approximate to 2 close to the value d 2 alpha 2 1 predicted by assuming that earthquake triggering is due to static stress the value d approximate to 2b implies that small earthquakes are as important as larger ones for stress transfers between earthquakes and that considering stress changes induced by small earthquakes should improve models of earthquake interactions

water balance modelling in lateritic terrain an analytical approximate model for unsaturated flow in a spatially variable field coupled with infiltration and evapotranspiration at the upper boundary and a fluctuating water table at the lower boundary has been developed the unsaturated flow equations depend on parameterizations of and k they are based on the notion of a moving discontinuous front the field heterogeneity refers to saturated hydraulic conductivity only horizontal variability is considered and the flow medium is approximated as a set of uncorrelated vertically homogeneous columns expectations and variances obtained with this approach have been compared with observations of the field hydrological processes three important aspects of the hydrology in this lateritic terrain are rapid water table response hortonian surface runoff generation and soil suction variability the stochastic conceptualization used explains to a high degree these characteristics although some limitations are demonstrated

veins in the lockport dolostone evidence for an acadian fluid circulation system the orientation and spatial distribution of veins in the lockport dolostone attest to a fluid circulation system active during the acadian orogeny in western new york and southern ontario outcrops east of the clarendon linden fault zone are cut by a prominent east northeast systematic calcite filled vein set whereas these systematic veins are absent west of the fault zone except in two quarries systematic veins display distinct characteristics the mean vein orientation rotates clockwise from 067 in the east to 086 farther west veins do not propagate into the basal lockport group and calcite vein 18 o pdb values are significantly lighter to the east of the clarendon linden fault zone maximum horizontal stress s h trend lines drawn parallel to the strike of the systematic veins are incompatible with s h inferred from alleghanian plateau and other post paleozoic structures however because east west s h trend lines are compatible with an acadian tectonic event in western new england our interpretation is that systematic veins in the lockport group are a cratonward signature of the acadian orogeny

environmental significance of bedrock jointing in southern ontario canada the bedrock surface of many glaciated areas is obscured by thick drift deposits in southern ontario canada the buried bedrock surface is dissected by channels infilled with glacial deposits as much as 150 m thick that are part of a wider mid continent preglacial fluvial system that predates formation of the modern great lake basins the infills of bedrock channels form major groundwater aquifers influence regional groundwater flows and contaminant migration to lake ontario and may localize the release of thermogenic methane and radon within heavily urbanized surface environments a quantitative comparison of the regional pattern of bedrock joints and the orientation pattern of buried bedrock channels and modern river valleys shows that all these orientation patterns are virtually coincident buried bedrock channels in south central ontario are not part of a simple antecedent drainage system but were likely predesigned by bedrock joint patterns that have subsequently been propagated upward into overlying pleistocene sediments joints in sediments are of considerable environmental significance for example subsurface contaminant and gas migration in fine grained clayey sediments and of many origins stress release desiccation etc but are widely assumed to be a predominantly surface related phenomena the existence of deeper joints has been noted by some authors but their origin is obscure data presented herein from south central ontario confirm that in addition to surface related joints a second population of bedrock related joints reflecting the upward propagation of bedrock fractures is present in pleistocene sediments of south central ontario

saddle dolomite and calcite cements as records of fluid flow during basin evolution paleogene carbonates united arab emirates abstract field observations indicate that tectonic compression anticline formation and concomitant uplift events of marine paleogene carbonates in eastern united arab emirates which are related to the zagros orogeny have induced brecciation karstification and carbonate cementation in vugs and along faults and fractures structural analysis stable isotopes and fluid inclusion microthermometry are used to constrain the origin and geochemical evolution of the fluids fluid flow was related to two tectonic deformation phases initially the flux of moderately 87 sr rich basinal nacl mgcl 2 h 2 o brines along reactivated deep seated strike slip faults have resulted in the precipitation of saddle dolomite in fractures and vugs and in dolomitization of host eocene limestones 18 o v pdb 15 8 to 6 2 homogenization temperatures of 80 115 c and salinity of 18 25 wt eq nacl subsequently compression and uplift of the anticline was associated with incursion of meteoric waters and mixing with the basinal brines which resulted in the precipitation of blocky calcite cement 18 o v pdb 22 to 12 homogenization temperatures of 60 90 c and salinity of 4 5 9 wt eq nacl saddle dolomite and surrounding blocky calcite have precipitated along the pre and syn folding e w fracture system and its conjugate fracture sets the stable isotopes coupled with fluid inclusion micro thermometry homogenization temperatures of 50 c and salinity of 87 sr rich cool meteoric waters this carbonate cementation history explains the presence of two correlation trends between the 18 o v pdb and 13 c v pdb values i a negative temperature dependent oxygen isotope fractionation trend related to burial diagenesis and to the flux of basinal brines and ii positive brine meteoric mixing trend this integrated study approach allows better understanding of changes in fluid composition and circulation pattern during evolution of foreland basins

global seismicity of 2001 centroid moment tensor solutions for 961 earthquakes abstract centroid moment tensor cmt solutions are presented for 961 earthquakes occurring during 2001 the solutions are obtained using corrections for aspherical earth structure represented by the whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward a m dziewonski r l woodward acoustic imaging at the planetary scale in h emert h p harjes eds acoustical imaging vol 19 plenum press new york 1992 pp 785 797 the model of anelastic attenuation of durek and ekstrom bull seism soc am 86 1996 144 is used to predict the decay of the waveforms

surface hydrology iv flow in sloping layered soil in a nonuniform soil with rotational symmetry the properties change along a coordinate n that forms an angle ia n with the vertical during infiltration there will be a flow component in the parallel direction s downstream which is proportional to the rain itself and the slope the horizontal flow is proportional to the vertical flow the slope and the coefficient of anisotropy the last has been calculated for a soil made up distinct layers in the limiting case of very thin layers or near the saturation point the vertical and horizontal conductivities are respectively the expected arithmetic and harmonic means familiar from saturated flow the coefficient of anisotropy increases with the rate of vertical flow to a power greater than unity the horizontal flow component can be many times the vertical one it finds application in pollution problems and in the study of the underground water regime

effective unsaturated hydraulic conductivity of layered sands accurate estimates of field scale hydraulic conductivities of unsaturated heterogeneous soils are very difficult to obtain in the present study various approaches to determining effective conductivity values for heterogeneous sands are compared with laboratory measurements the unsaturated hydraulic conductivity k of two homogeneous sands and one layered sand composed of the two homogeneous sands was measured using the steady state flux control method the averaged k curves of the two homogeneous sands using a direct averaging approach were compared with the measured layered sand k data the result shows that the geometric mean of hydraulic conductivity suction curves of the coarse and medium sands approximates the measured hydraulic conductivity suction curve of the layered sand the observed suction variance and effective hydraulic conductivity were compared with expressions developed from a stochastic theory the results support the stochastic approach

multiphase flow characteristics of heterogeneous rocks from co2 storage reservoirs in the united kingdom we have studied the impact of heterogeneity on relative permeability and residual trapping for rock samples from the bunter sandstone of the uk southern north sea the ormskirk sandstone of the east irish sea and the captain sandstone of the uk northern north sea reservoir condition co2 brine relative permeability measurements were made while systematically varying the ratio of viscous to capillary flow potential across a range of flow rates fractional flow and during drainage and imbibition displacement this variation resulted in observations obtained across a range of core scale capillary number 0 2 nc plh pc 200 capillary pressure heterogeneity was quantitatively inferred from 3 d observations of the fluid saturation distribution in the rocks for each of the rock samples a threshold capillary number 5 nc 30 was found below which centimeter scale layering resulted in a heterogeneous distribution of the fluid phases and a commensurate impact on flow and trapping the threshold was found to be dependent on the capillary number alone irrespective of the displacement path drainage or imbibition and average fluid saturation in the rock the impact of the heterogeneity on the relative permeability varied depending on the characteristics of the heterogeneity in the rock sample whereas heterogeneity increased residual trapping in all samples above what would be expected from the pore scale capillary trapping mechanism alone models of subsurface co2 injection should use properties that incorporate the impacts of heterogeneity at the flow regime of interest or risk significant errors in estimates of fluid flow and trapping

spatial averaging of unsaturated flow equations under infiltration conditions over areally heterogeneous fields 1 development of models unsaturated flows within subsurface regions control many large scale hydrological and environmental processes this study addresses the issue of spatial averaging of unsaturated flow equations at field scales two models for horizontally averaged unsaturated flow have been developed from two different approaches in this study the spatially horizontally averaged richards equation share model is represented by a system of two coupled partial differential equations for the mean water saturation in each horizontal soil layer and the cross covariance of the saturated hydraulic conductivity and the water saturation in each horizontal soil layer in a heterogeneous field as an alternative to the spatial averaging perturbation approach which was used for share a spatially horizontally averaged form of green ampt model is obtained by field scale spatial horizontal averaging of the local soil water dynamics which are represented approximately by rectangular profiles this strategy leads to analytical solutions for average water content and the results can be upscaled to large spatial areas the computational effort required to evaluate such analytic expressions is trivial in comparison with that of the numerical solution of richards equation the averaged green ampt model though approximate yields good results when large variations exist in the soil properties in the horizontal directions

estimation of the effective precipitation recharge coefficient in an unconfined aquifer using stochastic analysis effectively managing groundwater relies heavily on estimating the amount of precipitation that may infiltrate the subsurface and supply groundwater in this study we present a novel estimation method based on a stochastic approach to evaluate the quantity of precipitation that may recharge groundwater the precipitation recharge coefficient is also investigated based on an unconfined aquifer with an unbound infinitely extended boundary condition moreover a spectrum s relationship to the precipitation and groundwater level variation is also derived the precipitation recharge coefficient can be obtained from the solution of the spectrum equation furthermore sensitivity analysis is performed in order to determine the key variable on the precipitation recharge coefficient analysis results indicate that the location of an observation well affects the estimated precipitation recharge coefficient if the precipitation recharge area is large enough the precipitation recharge coefficient becomes insensitive to the location of the observation well the spectrum s relationship between the precipitation recharge and groundwater level variation is also applied when estimating the precipitation recharge coefficient upstream of the cho shui river alluvial fan according to those results the precipitation recharge coefficient is 0 03 and the amount of groundwater recharge from precipitation is 35 million tons of water annually upstream of the cho shui river alluvial fan copyright 2000 john wiley sons ltd

gravity currents with residual trapping motivated by geological carbon dioxide co 2 storage we present a vertical equilibrium sharp interface model for the migration of immiscible gravity currents with constant residual trapping in a two dimensional confined aquifer the residual acts as a loss term that reduces the current volume continuously in the limit of a horizontal aquifer the interface shape is self similar at early and at late times the spreading of the current and the decay of its volume are governed by power laws at early times the exponent of the scaling law is independent of the residual but at late times it decreases with increasing loss owing to the self similar nature of the current the volume does not become zero and the current continues to spread in the hyperbolic limit the leading edge of the current is given by a rarefaction and the trailing edge by a shock in the presence of residual trapping the current volume is reduced to zero in finite time expressions for the up dip migration distance and the final migration time are obtained comparison with numerical results shows that the hyperbolic limit is a good approximation for currents with large mobility ratios even far from the hyperbolic limit in gently sloping aquifers the current evolution is divided into an initial near parabolic stage with power law decrease of volume and a later near hyperbolic stage characterized by a rapid decay of the plume volume our results suggest that the efficient residual trapping in dipping aquifers may allow co 2 storage in aquifers lacking structural closure if co 2 is injected far enough from the outcrop of the aquifer

process dependent residual trapping of co2 in sandstone this paper demonstrates that the nature and extent of residual co2 trapping depend on the process by which the co2 phase is introduced into the rock we compare residual trapping of co2 in berea sandstone by imbibing water into a core containing either exsolved co2 or co2 introduced by drainage x ray computed tomography measurements are used to map the spatial distribution of co2 preimbibition and postimbibition unlike during drainage where the co2 distribution is strongly influenced by the heterogeneity of the rock the distribution of exsolved co2 is comparatively uniform postimbibition the co2 distribution retained the essential features for both the exsolved and drainage cases but twice as much residual trapping is observed for exsolved co2 even with similar preimbibition gas saturations residually trapped exsolved gas also disproportionately reduced water relative permeability development of process dependent parameterization will help better manage subsurface flow processes and unlock benefits from gas exsolution

lateral moisture flow beneath a sandy hillslope without an apparent impeding layer part of a small drainage basin on the sevilleta national wildlife refuge about 25 km north of socorro nm was intensively instrumented with soil monitoring equipment to estimate natural ground water recharge soil moisture data were analysed with special attention to characterizing the influence of topography on the direction of vadose water flow paths in fine to medium aeolian sand moisture content data were obtained by the neutron scattering technique and hydraulic head data were obtained using tensiometers in addition tracer experiments were conducted on a sandy hillslope to delineate the flow paths of vadose water the results indicate that there is a strong lateral component to unsaturated flow on a hillslope even in the absence of apparent sublayers of much lower permeability darcian calculations estimate the long term steady deep flux beneath a concave location to be about 4 per cent of an assumed mean annual precipitation of 20 cm the deep soil water flux downward varied by several orders of magnitude during the 17 month period of record

effect of groundwater recharge on configuration of the water table beneath sand dunes and on seepage in lakes in the sandhills of nebraska u s a comment

buoyant dispersal of co2 during geological storage carbon capture and storage is currently the only technology that may allow significant reductions in co2 emissions from large point sources seismic images of geological co2 storage show the rise of co2 is influenced by horizontal shales the buoyant co2 spreads beneath impermeable barriers until a gap allows its upward migration the large number and small scale of these barriers makes the prediction of the co2 migration path and hence the magnitude of co2 trapping very challenging we show that steady buoyancy dominated flows in complex geometries can be modeled as a cascade of flux partitioning events this approach allows the analysis of two dimensional plume dispersal from a horizontal injection well we show that the plume spreads laterally with height y above the source according to y h 1 2 l where l is the width of the shales and h is their vertical separation the fluid volume below successive shale layers and therefore the magnitude of trapped co2 increase as y h 5 4 above the source so that every additional layer of barriers traps more co2 than the one below upscaling small scale flow barriers by reducing the vertical permeability common in numerical simulations of co2 storage does not capture the dispersion and trapping of the co2 plume by the flow barriers

plate boundary forces are not enough second and third order stress patterns highlighted in the world stress map database 1 the world stress map project compiles a global database of contemporary tectonic stress information of the earth s crust early releases of the world stress map project demonstrated the existence of first order plate scale stress fields controlled by plate boundary forces and second order regional stress fields controlled by major intraplate stress sources such as mountain belts and zones of widespread glacial rebound the 2005 release of the world stress map project database provides for some areas high data density that enables us to investigate third order local stress field variations and the forces controlling them such as active faults local inclusions detachment horizons and density contrasts these forces act as major controls on the stress field orientations when the magnitudes of the horizontal stresses are close to isotropic we present and discuss examples for venezuela australia romania brunei western europe and southern italy where a substantial increase of data records demonstrates some of the additional factors controlling regional and local stress patterns

an inverse method for estimating thickness and volume with time of a thin co2 filled layer at the sleipner field north sea migration of co 2 through storage reservoirs can be monitored using time lapse seismic re ection surveys at the sleipner field injected co 2 is distributed throughout nine layers within the reservoir these layers are too thin to be seismically resolvable by direct measurement of the separation between re ections from the top and bottom of each layer here we develop and apply an inverse method for measuring thick ness changes of the shallowest layer our approach combines di erences in traveltime down to a speci c re ection together with amplitude measurements to determine layer thicknesses from time lapse surveys a series of synthetic forward models were used to test the robustness of our inverse approach and to quantify uncertainties in the absence of ambient noise this approach can unambiguously resolve layer thickness if a realistic ambient noise distribution is included layer thicknesses of 1 6 m are accurately retrieved with an uncertainty of 0 5 m we used this approach to generate a thickness map of the shallowest layer the delity of this result was tested using measurements of layer thickness determined from the 2010 broadband seismic survey the calculated volume of co 2 within the shallowest layer increases at a rate that is quadratic in time despite an approximately constant injection rate into the base of the reser voir this result is consistent with a diminished growth rate of the areal extent of underlying layers finally the relationship between caprock topography and layer thickness is explored and potential migration pathways that charge this layer are identi ed

source discriminants for near field tsunamis summary we present numerical simulations of tsunami run up in the near field for a data set of 72 models of sources involving both seismic dislocations and landslides by varying one by one the parameters describing the source and the receiving beach we are able to separate their individual influence on the amplitude and distribution of run up which we characterize by forming several dimensionless parameters principally the ratio i 2 of its maximum amplitude to its lateral extent along the beach we find that i 2 remains less than 10 4 for seismic dislocation sources but is greater than this threshold for all physically realistic models of underwater landslides thus it can be used as a discriminant for the nature of the source of a near field tsunami for seismic dislocations we also consider the ratio i 1 of maximum run up to seismic slip on the fault plane and validate numerically the previously suggested rule of thumb that this ratio cannot be much greater than 1 in the case of underwater landslides we show that the distribution of near field run up is primarily controlled by the 2 d wall of water displaced on the ocean surface as an initial condition to the simulation and is practically independent of its extension in the third dimension perpendicular to the beach we apply this approach to nine profiles of tsunami run up obtained experimentally during recent field surveys and show that our method successfully identifies the 1998 papua new guinea tsunami as having been generated by an underwater landslide thus confirming the results of shipboard and hydroacoustic investigations it also strongly suggests a similar mechanism for the generation of the near field aleutian tsunami of 1946 april 1

streamline based simulation of carbon dioxide storage in a north sea aquifer 1 we model carbon dioxide co2 storage into a deep north sea aquifer using streamline based simulation we assume incompressible flow of liquid like co2 and aqueous phases we simulate dissolution of co2 and a rate limited precipitation reaction advective transport and reactions are solved along streamlines while dispersion and flow due to gravity segregation of the phases are solved on the underlying grid geological storage is modeled on a one million cell model the distribution of co2 after injection is dominated by advective transport due to multiphase flow and co2 moves preferentially through high permeability channels without reaction the regional groundwater flow causes the co2 to continue to migrate until it reaches residual saturation where it continues slowly to dissolve precipitation leads to a decrease in porosity and permeability while co2 is stored in the solid phase the storage efficiency is low around 2 because of aquifer heterogeneity

capillary pressure and saturation relations for supercritical co2 and brine in sand high pressure pc sw controller meter measurements and capillary scaling predictions capillary pressure and saturation relations for supercritical co 2 and brine in sand high pressure p c s w controller meter measurements and capillary scaling predictions tetsu k tokunaga 1 jiamin wan 1 jong won jung 1 2 tae wook kim 1 3 yongman kim 1 and wenming dong 1 1 in geologic carbon sequestration reliable predictions of co 2 storage require understanding the capillary behavior of supercritical sc co 2 given the limited availability of measurements of the capillary pressure p c dependence on water saturation s w with scco 2 as the displacing fluid simulations of co 2 sequestration commonly rely on modifying more familiar air h 2 o and oil h 2 o p c s w relations adjusted to account for differences in interfacial tensions in order to test such capillary scaling based predictions we developed a high pressure p c s w controller meter allowing accurate p c and s w measurements drainage and imbibition processes were measured on quartz sand with scco 2 brine at pressures of 8 5 and 12 0 mpa 45 o c and air brine at 21 o c and 0 1 mpa drainage and rewetting at intermediate s w levels shifted to p c values that were from 30 to 90 lower than predicted based on interfacial tension changes augmenting interfacial tension based predictions with differences in independently measured contact angles from different sources led to more similar scaled p c s w relations but still did not converge onto universal drainage and imbibition curves equilibrium capillary trapping of the nonwetting phases was determined for p c 0 during rewetting the capillary trapped volumes for scco 2 were significantly greater than for air given that the experiments were all conducted on a system with well defined pore geometry homogeneous sand and that scco 2 brine interfacial tensions are fairly well constrained we conclude that the observed deviations from scaling predictions resulted from scco 2 induced decreased wettability wettability alteration by scco 2 makes predicting hydraulic behavior more challenging than for less reactive fluids and bachu 2008 benson and cole 2008 the depend ence of capillary pressure p c on water saturation s w under reservoir conditions is a basic constitutive relation needed to predict co 2 flow and capillary trapping during sequestration indeed with only knowledge of how rela tive permeability depends on s w neither fluid flow nor equilibrium saturation conditions are predictable at later stages of geologic carbon sequestration rewetting of reser voirs with native brine results in capillary trapping resid ual trapping of co 2 a main storage mechanism bachu et al 2007 ipcc 2005 the capillary trapping capacity of reservoir materials has complex dependence on porosity pore size distribution nonwetting phase displacement extent and the rewetting process iglauer et al 2011b tanino and blunt 2012 although capillary trapping of co 2 at its residual saturation depends on p c s w relations few investigations to date have directly measured these ba sic relations with co 2 h 2 o at reservoir pressures and tem peratures krevor et al 2011 pentland et al 2011 pini et al 2012 plug and bruining 2007 the study by plug and bruining 2007 appears to be the only one in which capillary trapped scco 2 saturation was determined while 1 introduction 2 geologic carbon sequestration may become an im portant technology for mitigating co 2 buildup in the atmosphere from fossil fuel combustion and for moderating climate change intergovernmental panel on climate change ipcc 2005 however predicting the perform ance of geologic co 2 sequestration requires reliable under standing of co 2 mobility and its saturation and pressure distribution within reservoirs bachu et al 2007 bennion earth sciences division lawrence berkeley national laboratory berkeley california usa now at civil and environmental engineering department louisiana state university baton rouge louisiana usa now at department of energy resources engineering stanford uni versity stanford california usa corresponding author t k tokunaga earth sciences division law rence berkeley national laboratory 1 cyclotron rd berkeley ca 94720 usa tktokunaga lbl gov

joint interaction with embedded concretions joint loading configurations inferred from propagation paths abstract the interaction between propagating joints and embedded concretions in a devonian black shale near seneca lake ny permits identification of the loading configurations responsible for two joint sets of different ages striking at nearly the same orientation the earlier set consists of systematic joints cut by later alleghanian joints of the appalachian plateau the later set consists of non systematic curving cross joints that abut these same alleghanian joints field evidence shows that concretions functioned as stiff inclusions in a compliant black shale as a consequence of this elastic contrast local perturbations in the remote stress field persisted around the concretions during burial tectonic deformation and exhumation these stress perturbations influenced joint propagation paths of both joint sets our conclusions about loading configurations are based on finite element modeling of the effect of the local stress perturbation on concretion modified joint propagation modeling shows that the local stress perturbation from a thermoelastic loading was responsible for deflecting cross joints away from concretions in a curved propagation path near the concretion this load configuration also led to arrest of cross joints before they penetrated the shale concretion interface at greater distances from the concretion the propagation path of cross joints was controlled by the contemporary tectonic stress field the interface between concretions and the surrounding shale was strongly bonded as indicated by the crossing of the interface by some of the systematic ene joints higher compressive stress levels within the concretions relative to the shale suppressed joint development in the concretion causing the arrest of those joints once they had driven across the interface and a short distance into the concretion numerical modeling shows that interface penetration by the systematic ene joints is consistent with a fluid load the same loading configuration postulated for the subsequent alleghanian joints the traces of the systematic ene joints align on opposite sides of concretions rather than curving toward the concretion as predicted by two dimensional models of the fluid load co planar traces are indicative of large planar joints propagating in plane around the concretion making it energetically inefficient for the crack front to curve as it enters the local stress perturbation near the concretion a fluid load for the systematic ene joints came from high pore pressure during the pre alleghanian stages of burial of the devonian catskill delta complex

tectonic interpretation of the andrew bain transform fault southwest indian ocean 1 between 25 e and 35 e a suite of four transform faults du toit andrew bain marion and prince edward offsets the southwest indian ridge swir left laterally 1230 km the andrew bain the largest has a length of 750 km and a maximum transform domain width of 120 km we show that currently the nubia somalia plate boundary intersects the swir east of the prince edward placing the andrew bain on the nubia antarctica plate boundary however the overall trend of its transform domain lies 10 clockwise of the predicted direction of motion for this boundary we use four transform parallel multibeam and magnetic anomaly profiles together with relocated earthquakes and focal mechanism solutions to characterize the morphology and tectonics of the andrew bain starting at the southwestern ridge transform intersection the relocated epicenters follow a 450 km long 20 km wide 6 km deep western valley they cross the transform domain within a series of deep overlapping basins bounded by steep inward dipping arcuate scarps eight strike slip and three dip slip focal mechanism solutions lie within these basins the earthquakes can be traced to the northeastern ridge transform intersection via a straight 100 km long 10 km wide 4 5 km deep eastern valley a striking set of seismically inactive ne sw trending en echelon ridges and valleys lying to the south of the overlapping basins dominates the eastern central section of the transform domain we interpret the deep overlapping basins as two pull apart features connected by a strike slip basin that have created a relay zone similar to those observed on continental transforms this transform relay zone connects three closely spaced overlapping transform faults in the southwest to a single transform fault in the northeast the existence of the transform relay zone accounts for the difference between the observed and predicted trend of the andrew bain transform domain we speculate that between 20 and 3 2 ma an oblique accretionary zone jumping successively northward created the en echelon ridges and valleys in the eastern central portion of the domain the style of accretion changed to that of a transform relay zone during a final northward jump at 3 2 ma

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

early jointing in coal and black shale evidence for an appalachian wide stress field as a prelude to the alleghanian orogeny early ene striking joints present coordinates within both pennsylvanian coal and devonian black shale of the central and southern appalachians reflect an approximately rectilinear stress field with a dimension 1500 km this appalachian wide stress field awsf dates from the time of joint propagation when both the coal and shale were buried to the oil window during the 10 15 m y period straddling the pennsylvanian permian boundary the awsf was generated during the final assembly of pangea as a consequence of plate boundary tractions arising from late stage oblique convergence where maximum horizontal stress s h of the awsf was parallel to the direction of closure between gondwana and laurentia after closure the awsf persisted during dextral slip of peri gondwanan microcontinents when sh appears to have crosscut plate scale trans current faults at around 30 sup o following 10 m y of dextral slip during tightening of gondwana against laurentia the awsf was disrupted by local stress fields associated with thrusting on master basement decollements to produce the local orocline shaped alleghanian map pattern seen today

the relationship between evolution of fluid chemistry and the style of brittle deformation examples from the northern apennines italy abstract vein systems related to faults and thrusts are often filled by carbonate phases that carry a chemical composition reflecting the fluids once permeating the rocks evidence of important fluid circulation is documented at the northwestern and southern edges of the northern apennines in the monferrato and sabina regions respectively in veins linked to transpressive faults transtensional faults and thrusts the compositional ranges are the following in monferrato 11 2 13 c 7 8 18 o 0 708017 87 sr 86 sr 0 14 7 3 13 c 6 0 18 o 0 70736 87 sr 86 sr 0 30

earthquake slip distribution a statistical model 1 the purpose of this paper is to interpret slip statistics in a framework of extended earthquake sources we first discuss deformation pattern of the earth s surface from earthquakes and suggest that continuum versus block motion controversy can be reconciled by a model of the fractal distribution of seismic sources we consider earthquake slip statistical distributions as they can be inferred from seismic moment frequency relations and geometrical scaling for earthquakes using various assumptions on temporal earthquake occurrence these distributions are synthesized to evaluate the accuracy of geologic fault slip determinations and to estimate uncertainties in long term earthquake patterns based on paleoseismic data because the seismic moment distribution is a power law pareto a major part of the total seismic moment is released by major earthquakes m 10 19 5 n m moment magnitude m 7 for these large earthquakes the rupture is confined to the upper brittle crust layer we review the various moment frequency and earthquake scaling relationships and apply them to infer the slip distribution at area and site specific regions simulating the seismic moment and strain accumulation process demonstrates that some synthetics can be interpreted as examples of a quasiperiodic sequence we demonstrate the application of the derived slip statistical relations by analyzing the slip distribution and history of the san andreas fault at wrightwood california

mapping the upper mantle three dimensional modeling of earth structure by inversion of seismic waveforms a method is presented for the inversion of waveform data for the three dimensional distribution of seismic wave velocities the method is applied to data from the global digital networks international deployment of accelerometers global digital seismograph network the selected data set consists of some 2000 seismograms corresponding to 53 events and 870 paths the moment tensors of the earthquakes are determined through an iterative procedure which minimizes the corrupting influence of lateral heterogeneity a global model is constructed for shear wave velocity expanded up to degree and order 8 in spherical harmonics and described by a cubic polynomial in depth for the upper 670 km of the earth s mantle although no a priori information is incorporated the model predictions reproduce much of what is known about the dispersion of mantle waves for example high phase velocities for shields low velocities at ridges and a strong degree 2 pattern for rayleigh waves since the method makes use of complete waveforms overtone data are also included it is shown that the model is reproducible in that substantially the same model can be constructed from each half of the total data set considered independently the model shows that shields and ridges are major features in the depth interval 25 250 km the ridges of the southern pacific and the larger shields persist to 350 km but the southeast indian rise is underlain by a high velocity anomaly at this depth as is much of the mid atlantic ridge at 450 650 km the major features are a broad region of high velocities incorporating south america much of the south atlantic and parts of west africa a broad region of low velocities in the central and eastern pacific high velocities in the western pacific and a low velocity anomaly beneath the red sea and the gulf of aden in the absence of a crustal correction degrees 2 and 3 show a high positive correlation with the geoid paradoxically this is largely destroyed when the distribution in crustal thickness is taken into account spherical harmonic degrees 4 7 show a significant negative correlation

benchmarking of vertically integrated co2 flow simulations at the sleipner field north sea abstract numerical modeling plays an essential role in both identifying and assessing sub surface reservoirs that might be suitable for future carbon capture and storage projects accuracy of flow simulations is tested by benchmarking against historic observations from on going co2 injection sites at the sleipner project located in the north sea a suite of time lapse seismic reflection surveys enables the three dimensional distribution of co2 at the top of the reservoir to be determined as a function of time previous attempts have used darcy flow simulators to model co2 migration throughout this layer given the volume of injection with time and the location of the injection point due primarily to computational limitations preventing adequate exploration of model parameter space these simulations usually fail to match the observed distribution of co2 as a function of space and time to circumvent these limitations we develop a vertically integrated fluid flow simulator that is based upon the theory of topographically controlled porous gravity currents this computationally efficient scheme can be used to invert for the spatial distribution of reservoir permeability required to minimize differences between the observed and calculated co2 distributions when a uniform reservoir permeability is assumed inverse modeling is unable to adequately match the migration of co2 at the top of the reservoir if however the width and permeability of a mapped channel deposit are allowed to independently vary a satisfactory match between the observed and calculated co2 distributions is obtained finally the ability of this algorithm to forecast the flow of co2 at the top of the reservoir is assessed by dividing the complete set of seismic reflection surveys into training and validation subsets we find that the spatial pattern of permeability required to match the training subset can successfully predict co2 migration for the validation subset this ability suggests that it might be feasible to forecast migration patterns into the future with a degree of confidence nevertheless our analysis highlights the difficulty in estimating reservoir parameters away from the region swept by co2 without additional observational constraints

experimental analysis of spatial correlation effects on capillary trapping of supercritical co2 at the intermediate laboratory scale in heterogeneous porous media author s trevisan l pini r cihan a birkholzer jt zhou q illangasekare th abstract 2015 american geophysical union all rights reserved several numerical studies have demonstrated that the heterogeneous nature of typical sedimentary formations can favorably dampen the accumulation of mobile co2 phase underneath the caprock core flooding experiments have also shown that contrasts in capillary entry pressure can lead to buildup of nonwetting fluid phase nwp at interfaces between facies explicit representation of geological heterogeneity at the intermediate cm to m scale is a powerful approach to identify the key mechanisms that control multiphase flow dynamics in porous media the ability to carefully control flow regime and permeability contrast at a scale that is relevant to co2 plume dynamics in saline formations offers valuable information to understand immiscible displacement processes and provides a benchmark for mathematical models to provide insight into the impact of capillary heterogeneity on flow dynamics and trapping efficiency of supercritical co2 under successive drainage and imbibition conditions we present an experimental investigation conducted in a synthetic sand reservoir by mimicking the interplay of governing forces at reservoir conditions via application of surrogate fluids we performed three immiscible displacement experiments to observe the entrapment of nwp in heterogeneous porous media capillary trapping performance is evaluated for each scenario through spatial and temporal variations of nwp saturation for this reason we adopted x ray attenuation to precisely measure phase saturation throughout the flow domain and apply spatial moment analysis the sweeping performance of two different permeability fields with comparable variance but distinct spatial correlation was compared against a homogeneous base case with equivalent mean permeability by means of spatial moment analysis

temporal moment analysis for stochastic advective vertical solute transport in heterogeneous unsaturated soils summary temporal moment analysis of solute transport in unsaturated soils subjected to rainfall events is typically achieved by the numerical solution of the flow field from the richards equation followed by a numerical solution of the advection dispersion equation before computing moments these numerical solutions are computationally very intensive and may not provide the insights that are possible from simpler analytical representations in this study temporal moments of solute transport for unsteady unsaturated flows under rainfall conditions at the soil surface are presented for the first time a local scale model for water movement is derived from a sharp front approximation and is combined with a model for transport of solute particles along the main characteristics of the flow field expressions for travel times from the local scale model are first presented for pre and post ponding conditions these local solutions are upscaled to field scale solute transport by adopting a log normally distributed spatial hydraulic conductivity field semi analytical expressions are developed for temporal moments of travel times these expressions are compared to 1 d monte carlo simulation results and to 3 d numerical results for model corroboration the model is used to investigate the behavior of macroscopic eulerian effective velocities and dispersion at the field scale expressions for asymptotic effective properties show that effective velocity achieves a constant value while effective dispersion increases linearly with depth the roles of pre ponding and post ponding conditions in determining field scale dispersion are described

geologic and hydrologic controls on the movement of water through a thick heterogeneous unsaturated zone underlying an intermittent stream in the western mojave desert southern california 1 a two dimensional axially symmetric unsaturated flow model was developed to test hypotheses about geologic and hydrologic controls on the movement of water through the thick heterogeneous unsaturated zone underlying oro grande wash in the mojave desert california heterogeneity within the unsaturated zone was simulated with multiple realizations of subsurface geology estimated on the basis of transition probability markov chain statistics model results show lateral spreading of water away from the wash was best approximated by realizations that include thin horizontally extensive clay layers that impede the downward movement of water there was a wide range in model responses for these realizations and the movement of water through unsaturated zones containing thin horizontally extensive clay layers may be more difficult to predict than water movement through unsaturated zones where clay layers are less extensive for realizations having less extensive clay layers the range of model responses decreased with time and model results became increasingly similar as water encountered larger volumes of material

capillary heterogeneity trapping of co2 in a sandstone rock at reservoir conditions 1 the storage of co2 in deep subsurface porous rocks is being developed worldwide for the mitigation of emission from large industrial sources such as power plants and steel manufacturing a main concern of this technology is in ensuring that the upwardly buoyant co2 does not migrate to the surface simulation studies suggest that substantial amounts of co2 can be trapped within permeable sections of a reservoir by capillary forces and intra reservoir heterogenities but there is little experimental observation of these phenomena we report the results of co2 core flooding experiments at high pressure and temperature performed to investigate the impact of natural capillary heterogeneity in a sandstone rock on co2 saturation buildup and trapping co2 and water were injected through a mt simon sandstone core at 9 mpa pore pressure and 50 c the core had two regions of distinct capillarity an upstream 10 cm long region of the core consisted of a relatively high permeability and homogenous sand a downstream 3 cm long region of the core consisted of a low permeability region characterized by significant cross bedding and a high capillary entry pressure for co2 during a drainage process of co2 displacing water co2 builds up upstream of the capillary barrier once in place co2 on the upstream side of the barrier cannot be displaced during 100 water flooding leading to trapped saturations that are a factor 2 5 times higher than what would be expected from residual trapping alone

deep focus repeating earthquakes in the tonga fiji subduction zone abstract deep focus earthquakes in the tonga fiji subduction zone make up greater than 66 of the globally recorded deep seismicity the high number of deep focus seismicity in this active subduction zone allows us to search for deep focus similar earthquake pairs and repeating earthquakes we compile a waveform dataset for deep earthquakes with magnitude above 4 7 occurring in the tonga fiji kermadec subduction zone recorded teleseismically between 1990 and 2009 we identify 8 similar clusters and 18 similar doublets with an average cross correlation coefficient greater than 0 8 among more than 45 000 potential earthquake pairs these similar doublets and clusters are located in the central part of the tonga fiji slab at the depth range of 480 650 km a master event relocation algorithm is used to determine the precise relative location and depth among these similar earthquake pairs we estimate and superpose circular fault areas for these similar clusters and doublets and find that one similar doublet appears to be a deep repeating earthquake pair this deep doublet has a small separation less than 0 4 km and overlapping rupture areas indicating that the same fault appears to slip other deep similar earthquake pairs are spatially offset or do not exhibit overlapping rupture areas time separation is on the order of years for the majority of similar earthquake pairs thermal plastic shear instability is more likely to explain these deep repeating earthquakes and similar earthquake pairs

mapping soil layers using electrical resistivity tomography and validation sandbox experiments abstract knowledge of the geologic structure at a field site is a useful piece of information for hydrologic modeling since it can serve as more site specific prior information about the hydraulic parameter patterns at the site than generic spatial statistics widely accepted electrical resistivity tomography ert survey for mapping subsurface anomalies could be a viable tool for acquiring this information however their ability to delineate geologic structures has not been thoroughly investigated in this study two dimensional ert numerical experiments were first conducted to study the effects of boundary conditions on the dipole dipole and pole pole array configurations an ert setup subsequently was implemented in a sandbox consisting of complex layers of different sands a continuous copper wire was installed along the sides of the sandbox to impose potential boundaries using data collected with the pole pole array in the sandbox under different degrees of drainage and the successive linear estimator sle algorithm we show that ert yields electrical conductivity estimates of complex layer structures with small uncertainties in addition using sle with physically meaningful correlation scales as prior information can lead to an electrical conductivity field that is consistent with visually observed layer structures the correlation scale concept also was demonstrated to provide guidance to the design of the electrode spacing in the surveys moreover the estimated field was validated by predicting electrical potential fields from two independent ert surveys using electrodes at different locations results of this study suggest that the combination of ert and sle is a viable geophysical survey tool for mapping geologic layer structures research significance this study develops a method to implement prescribed potential boundaries for enhancing the pole pole ert survey illustrates the importance of correlation scales and develops an approach for validating ert results

three phase flow in porous media a review of experimental studies on relative permeability we present a detailed synthesized review of experimental studies on three phase relative permeability published since 1980 we provide comprehensive yet highly focused analysis of critical aspects of the field and their evolution over the last three decades in particular we review the effects of saturation history wettability spreading and layer drainage on the measured flow properties we also list all the processes rock types fluid systems and measurement techniques in order to provide a clear map for future studies behavior of the measured three phase relative permeabilities with respect to fluid saturations saturation histories wettability of rock samples spreading characteristics interfacial tensions and other pertinent properties are carefully discussed studies that use a diverse set of experimental techniques and data analysis to deduce relative permeability are included the experimental techniques that should be utilized to reduce uncertainty are also explored we interpret the measured properties and outcomes of different studies and compare them to substantiate distinct trends at various saturation ranges and provide ideas for new studies this is intended to distill a clear image of where the field stands and to allow composition of possible paths for future investigations the areas of critical relevance that have not been investigated or require further studies are highlighted

simulation of field injection experiments in heterogeneous unsaturated media using cokriging and artificial neural network 1 simulations of moisture flow in heterogeneous soils are often hampered by lack of measurements of soil hydraulic parameters making it necessary to rely on other sources of information in this paper we develop a methodology to integrate data that can be easily obtained for example initial moisture content i bulk density and soil texture with data on soil hydraulic properties via cokriging and artificial neural network ann based pedotransfer functions the method is applied to generate heterogeneous soil hydraulic parameters at a field injection site in southeastern washington state stratigraphy at the site consists of imperfectly stratified layers with irregular layer boundaries cokriging is first used to generate three dimensional heterogeneous fields of bulk density and soil texture using an extensive data set of field measured i which carry signature about site heterogeneity and stratigraphy soil texture and bulk density are subsequently input into an ann based site specific pedotransfer function to generate three dimensional heterogeneous soil hydraulic parameter fields the stratigraphy at the site is well represented by the estimated pedotransfer variables and soil hydraulic parameters the parameter estimates are then used to simulate a field injection experiment at the site a relatively good agreement is obtained between the simulated and observed moisture contents the spatial distribution pattern of observed moisture content as well as the southeastward moisture movement is captured well in the simulations in contrast to earlier work using an effective parameter approach yeh et al 2005 we are able to reproduce the observed splitting of the moisture plume in a coarse sand unit that is sandwiched between two fine textured units the simple method of combining cokriging and ann for site characterization provides unbiased prediction of the observed moisture plume and is flexible so that additional measurements of various types can be included as they become available

stochastic analysis of moisture plume dynamics of a field injection experiment 1 a vadose zone field injection experiment was conducted in the summer of 2000 at the hanford site washington the unique moisture content database is used to identify the lithology at the field site and to interpret visualize and quantify the spatiotemporal evolution of the three dimensional 3 d moisture plume created by the injection experiment we conducted a hierarchical geostatistical analysis to examine the large scale geologic structure for the entire field site and then investigated small scale features within different layers afterward variogram analysis was applied to the field measured for seven different days during the injection experiment temporal variations of sills and ranges are related to the observed moisture plume dynamics a visualization of the 3 d moisture plume evolution illustrates effects of media heterogeneity statistics of changes in moisture content as a function of distance reveal large variance near the wetting front the coefficient of variation increases with decreasing mean these findings support the gradient and mean dependent variability in the moisture content distribution as reported by existing stochastic theories spatial moment analysis is also conducted to quantify the rate and direction of movement of the plume mass center and its spatial spreading the ratio of horizontal to vertical spreading at varying moisture contents suggests moisture dependent anisotropy in effective unsaturated hydraulic conductivity confirming existing stochastic theories however the principal directions of the spatial moments are found to vary as the moisture plume evolves through local heterogeneity a feature that has not been recognized in the theories

the impact of reservoir conditions on the residual trapping of carbon dioxide in berea sandstone the storage of carbon dioxide in deep brine filled permeable rocks is an important tool for co2 emissions mitigation on industrial scales residual trapping of co2 through capillary forces within the pore space of the reservoir is one of the most significant mechanisms for storage security and is also a factor determining the ultimate extent of co2 migration within the reservoir in this study we have evaluated the impact of reservoir conditions of pressure temperature and brine salinity on the residual trapping characteristic curve of a fired berea sandstone rock the observations demonstrate that the initial residual characteristic trapping curve is invariant across a wide range of pressure temperature and brine salinities and is also the same for co2 brine systems as a n2 water system the observations were made using a reservoir condition core flooding laboratory that included high precision pumps temperature control the ability to recirculate fluids for weeks at a time and an x ray ct scanner experimental conditions covered pressures of 5 20 mpa temperatures of 25 50 c and 0 5 mol kg nacl brine salinity a novel coreflooding approach was developed making use of the capillary end effect to create a large range in initial co2 saturation 0 15 0 6 in a single coreflood upon subsequent flooding with co2 equilibriated brine the observation of residual saturation corresponded to the wide range of initial saturations before flooding resulting in a rapid construction of the initial residual curve for each condition we report the initial residual curve and the resulting parameterization of the land hysteresis models

estimation of effective unsaturated hydraulic conductivity tensor using spatial moments of observed moisture plume 1 knowledge of unsaturated zone hydraulic properties is critical for many environmental and engineering applications various stochastic methods have been developed during the past 2 decades to estimate the effective unsaturated hydraulic properties independent of these stochastic methods we develop in this paper a practical approach to estimate the three dimensional 3 d effective unsaturated hydraulic conductivity tensor using spatial moments of 3 d snapshots of a moisture plume under transient flow conditions an application of the new approach to data collected at the hanford site in southeastern washington state yields an effective unsaturated hydraulic conductivity tensor that exhibits moisture dependent anisotropy the effective hydraulic conductivities compare well with laboratory measured unsaturated hydraulic conductivity data from small core samples they also reproduce the general behavior of the observed moisture plume at the site we also define a moisture diffusivity length concept which we use in conjunction with estimated correlation scales of the geologic media at the field site to explain deviations between the observed and simulated plumes based on the derived effective hydraulic properties

horizontal slip along alleghanian joints of the appalachian plateau evidence showing that mild penetrative strain does little to change the pristine appearance of early joints abstract some alleghanian joints in black shales of the geneseo and middlesex formations of the catskill delta complex finger lakes district new york slipped horizontally up to 8 cm horizontal slip is measured by the offset of ene striking joints alleghanian joints striking 330 350 display a right lateral slip with an average value of 1 9 cm while joints striking 004 010 slip in the left lateral sense with an average value of 1 3 cm the maximum horizontal stress sh driving this slip falls between 350 and 004 the orientation of local alleghanian layer parallel shortening as indicated by both disjunctive and pencil cleavage by commonality of orientation we infer that slip on alleghanian joints is driven contemporaneously with layer parallel shortening if so the offset ene striking joints predate the alleghanian stress field these observations mean that both pre alleghanian and early alleghanian joints persist through a period of penetrative strain

controls and age of cavernous porosity in middle silurian dolomite southern ontario porosity in bioclastic dolomites of the amabel formation in the eramosa river area northeast of guelph ontario is characterized by solution enlarged joints in outcrop kluftkarren and vuggy and cavernous intervals in the subsurface in addition a network of accessible caves has been dissected by recent fluvial incision by the present eramosa river valley porosity development was controlled locally by lithostratigraphy and regionally by the progressive downcutting of a deeply incised buried bedrock valley west of rockwood the amabel formation is capped by the eramosa member of the guelph formation which consists of jointed but relatively nonporous laminated to medium bedded bituminous dolomitized mudstones the vuggy and cavernous porosity in the amabel formation is probably pre wisconsinan to early wisconsinan in age beginning more than 60 75 ka and developed in response to the lowering of hydraulic gradients as the channel of the rockwood buried valley was progressively incised porous inte

effective hydraulic conductivities of transient unsaturated flow in stratified soils the effective hydraulic conductivities of transient unsaturated flow in stratified soils are evaluated using a three dimensional stochastic approach because of the disparity of the correlation scales in a stratified soil the general stochastic equations are simplified and this allows analytical evaluation and derivation of generic expressions for the effective hydraulic conductivities simple asymptotic expressions valid at particular ranges of the soil property and the mean flow characteristics are also derived several examples illustrating the results using data from two real soils are also presented it was found that the effective hydraulic conductivities show significant hysteresis and are anisotropic with a degree of anisotropy depending on the mean flow conditions wetting or drying such hysteresis and anisotropy are produced by the spatial variability of the hydraulic soil properties rather than hysteresis or anisotropy of the local parameters a physical interpretation of the results is given along with a qualitative comparison with field observations the ramifications of this study need to be further investigated and be considered in field applications such as waste disposal control

co2 wettability of seal and reservoir rocks and the implications for carbon geo sequestration we review the literature data published on the topic of co2 wettability of storage and seal rocks we first introduce the concept of wettability and explain why it is important in the context of carbon geo sequestration cgs projects and review how it is measured this is done to raise awareness of this parameter in the cgs community which as we show later on in this text may have a dramatic impact on structural and residual trapping of co2 these two trapping mechanisms would be severely and negatively affected in case of co2 wet storage and or seal rock overall at the current state of the art a substantial amount of work has been completed and we find that sandstone and limestone plus pure minerals such as quartz calcite feldspar and mica are strongly water wet in a co2 water system oil wet limestone oil wet quartz or coal is intermediate wet or co2 wet in a co2 water system the contact angle alone is insufficient for predicting capillary pressures in reservoir or seal rocks the current contact angle data have a large uncertainty solid theoretical understanding on a molecular level of rock co2 brine interactions is currently limited in an ideal scenario all seal and storage rocks in cgs formations are tested for their co2 wettability achieving representative subsurface conditions especially in terms of the rock surface in the laboratory is of key importance but also very challenging

short term properties of earthquake catalogs and models of earthquake source i review the short term properties of earthquake catalogs in particular the time and size distributions and the completeness of the early part of aftershock sequences for strong shallow earthquakes i determine the parameters of the omori and gutenberg richter laws for aftershocks close in time to a mainshock aftershock sequences of large earthquakes in southern california 1952 kern county 1992 joshua tree landers big bear sequence 1994 northridge and 1999 hector mine recorded in the caltech catalog are analyzed to demonstrate that at the beginning of these series many small earthquakes are absent from the catalog the number of missing earthquakes increases with the magnitude range of a catalog and for some data sets exceeds the number of aftershocks close to a mainshock listed in a catalog comparing global earthquake catalogs harvard centroid moment tensor and preliminary determination of epicenter with local data sets indicates that the catalogs based on longer period waves miss many early aftershocks even when their magnitudes are well above the stated magnitude threshold such short term incompleteness may introduce significant biases to the statistical analysis of the seismicity pattern in particular for branching models of earthquake occurrence incorporating the omori law for such models the likelihood function strongly depends on close aftershocks i review the techniques to alleviate this problem analyzing the source rupture process of several recent large earthquakes suggests that rupture propagation is highly inhomogeneous in space time and focal mechanism these random variations in the rupture process can be viewed as an extension of the aftershock stochastic generating mechanism toward the origin time of a mainshock i review various models of the earthquake rupture process and suggest that fractal distributions of microevents in time space and focal mechanism constitute the development of an earthquake the final identification of an individual earthquake depends on both objective and subjective factors manuscript received 21 may 2003

steady convective flow in an unsaturated state dependent anisotropic soil profile analysis of the affected zone from a contaminating point source summary anisotropy of the medium plays a dominant role in shaping the flow pattern in the soil profile this study analyses the effect of anisotropy on the horizontal spreading of the flow trajectories from a contaminating source point at the soil surface to a high water table it considers a phreatic aquifer with infinite lateral extension and uniform sedimentary layered soil profile where a state dependent anisotropy factor sdaf a and mualem s 1984 anisotropy model might be applicable the numerically calculated streamlines portray the effect of anisotropy and allow discernment among various anisotropic media different flow cases are analyzed with regard to their dependence on a as well as their dependence on the infiltration rate and on the orientation of the principal axes theory indicates that the flux direction is dependent on the capillary head and thus on the flow rate consequently it is the infiltration rate which determines the particular path line from the contaminant source point to the ground water table accordingly we have defined the affected domain as the domain within the unsaturated profile which is vulnerable to contamination from a source point at the soil surface and the affected segment as the segment on the phreatic surface where pollutants may potentially reach the ground water aquifer both are determined with respect to anisotropy infiltration rate and depth the non linear horizontal shift of the contaminant trajectory indicates that a substantial error may result when adopting a constant anisotropy factor this study suggests that the maximal horizontal shift is the relevant scale when characterizing the anisotropic flow system this measure should be taken into consideration when designing a related laboratory experiment or a field monitoring system

stochastic analysis of transient flow in unsaturated heterogeneous soils a stochastic unsaturated water flow model is developed for heterogeneous soils subject to a transient flow regime equations are developed for a fully three dimensional soil profile and results are presented for an example one dimensional problem the model predicts the mean and covariance of the soil water content darcy s flux and pore water velocity as a function of the boundary flux and saturated hydraulic conductivity statistics the statistics of the pore water velocity can be used to predict solute transport in soils as shown by foussereau et al this issue approximate flow related moment equations are solved analytically in the laplace domain then the analytical results are numerically inverted using a modified fast fourier transform algorithm the model predictions are compared to results obtained from monte carlo simulations for two different boundary flux patterns characteristic of humid climates and two different soil types a fine sand and a sandy loam comparing the approximate solutions of the statistical moments to the outputs of the monte carlo simulations shows 1 the dominance of the boundary flux variability over that of the saturated conductivity on the overall prediction uncertainty particularly at shallow depths and 2 the good performance of the stochastic unsaturated flow model particularly for fine textured soils subject to boundary fluxes with coefficients of variation up to 1 5 as the boundary flux coefficient of variation increases and the soil becomes coarser the model performance deteriorates because the flow system becomes significantly more nonlinear

plate tectonic analysis of shallow seismicity apparent boundary width beta corner magnitude coupled lithosphere thickness and coupling in seven tectonic settings a new plate model is used to analyze the mean seismicities of seven types of plate boundary crb continental rift boundary ctf continental transform fault ccb continental convergent boundary osr oceanic spreading ridge otf oceanic transform fault ocb oceanic convergent boundary sub subduction zone we compare the platelike nonorogen regions of model pb2002 bird 2003 with the centroid moment tensor cmt catalog to select apparent boundary half widths and then assign 95 of shallow earthquakes to one of these settings a tapered gutenberg richter model of the frequency moment relation is fit to the subcatalog for each setting by maximum likelihood best fitting values range from 0 53 to 0 92 but all 95 confidence ranges are consistent with a common value of 0 61 0 66 to better determine some corner magnitudes we expand the subcatalogs by 1 inclusion of orogens and 2 inclusion of years 1900 1975 from the catalog of pacheco and sykes 1992 combining both earthquake statistics and the plate tectonic constraint on moment rate corner magnitudes include the following crb graphic 1 ctf graphic 2 ccb graphic 3 ocb graphic 4 and sub graphic 5 coupled lithosphere thicknesses are found to be the following crb graphic 6 ctf graphic 7 ccb graphic 8 osr graphic 9 for normal faulting and graphic 10 for strike slip otf graphic 11 and graphic 12 at low medium and high velocities ocb graphic 13 and sub graphic 14 in general high coupling of subduction and continental plate boundaries suggests that here all seismic gaps are dangerous unless proven to be creeping in general low coupling within oceanic lithosphere suggests a different model of isolated seismic fault patches surrounded by large seismic gaps that may be permanent online material global seismic subcatalogs of shallow earthquakes 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif 4 embed inline graphic 4 gif 5 embed inline graphic 5 gif 6 embed inline graphic 6 gif 7 embed inline graphic 7 gif 8 embed inline graphic 8 gif 9 embed inline graphic 9 gif 10 embed inline graphic 10 gif 11 embed inline graphic 11 gif 12 embed inline graphic 12 gif 13 embed inline graphic 13 gif 14 embed inline graphic 14 gif

4d multi scale imaging of reactive flow in carbonates assessing the impact of heterogeneity on dissolution regimes using streamlines at multiple length scales abstract we have experimentally investigated the impact of heterogeneity on the dissolution of two limestones characterised by distinct degrees of flow heterogeneity at both the pore and core scales the two rocks were reacted with reservoir condition co2 saturated brine at both scales and scanned dynamically during dissolution first 1 cm long 4 mm diameter cores were scanned during reactive flow with a 4 m voxel size between 10 and 71 times using 4d x ray micro tomography ct over the course of 90 min second 3 8 cm diameter 8 cm long cores were reacted at the same conditions inside a reservoir condition flow apparatus and imaged using a medical grade x ray computed tomography scanner xct each sample was imaged 13 times over the course of 90 min at a 250 250 500 m resolution these larger cores were then scanned inside a ct at a 27 m voxel size to assess the alteration pore space heterogeneity after reaction both rock types exhibited channel widening at the mm scale and progressive high porosity pathway dissolution at the cm scale in the more heterogeneous rock dissolution was more focussed and progressed along the direction of flow additionally the dissolution pathways contained a distinct microstructure captured with the ct that was not visible at the resolution of the xct where the reactive fluid had not completely dissolved the internal pore structure this microstructure was further analyzed by performing a direct simulation of the flow field and streamline tracing on the image voxels we found that at the larger scales the interplay between flow and reaction significantly affects flow in the unreacted regions of the core when flow is focussed in large reacted channels this focusing is carried through to the unreacted parts of the rock where flow continues to be confined to preferential pathways after passing the reaction front this focussing effect is greater with increasing pore space heterogeneity indicating that the representative elementary volume rev for dissolution is far greater than the dissolution front itself this study of scale dependence using in situ 4d tomography provides insight into the mechanisms that control local reaction rates at the mm and cm scales furthermore this work suggests that under these conditions at larger scales it is likely to be structural heterogeneity that dominates the pattern of dissolution and therefore the evolution of high permeability pathways

effects of hydraulic conductivity heterogeneity on vadose zone response to pumping in an unconfined aquifer summary it is of great importance to be able to properly simulate flow mechanisms within the vadose zone as they are controlling factors for solute transport to groundwater bodies the highly detailed pumping test data set collected by bevan et al 2005 at the borden aquifer provides a unique opportunity to investigate the controlling factors for fluid flow and moisture distribution in the vadose zone in response to pumping the field results show capillary fringe thicknesses that increased with duration of pumping and decreased with distance from the well this increased thickness was persistent for the duration of the 7 day test previous numerical analysis of the pumping test has been able to replicate the observed moisture contents at discrete time intervals moench 2008 but the physical mechanisms controlling the moisture content observations are poorly understood hydraulic conductivity heterogeneity has been proposed as a potential mechanism for the capillary fringe extension observed in the field using stochastic hydraulic conductivity fields moisture content distributions observed during the bevan et al 2005 pumping test were simulated using a variably saturated numerical model a monte carlo analysis was performed and ensemble results are presented the ensemble mean hydraulic head drawdown was an adequate match to the field data although there was a small but consistent over prediction of drawdown the ensemble mean thickness of the capillary fringe was not significantly different from the result of a homogeneous simulation and did not replicate the increasing thickness observed in the field the ensemble mean capillary fringe extension was not found to be dependent upon distance from the pumping well or duration of pumping zones of perched water were formed in many of the heterogeneous realizations however neutron probe data collected during the field experiment does not support the presence of these perched zones

an experiment in systematic study of global seismicity centroid moment tensor solutions for 201 moderate and large earthquakes of 1981 data from the global digital seismograph network were used to obtain centroid moment tensor solutions using the method of dziewonski et al 1981 results were obtained for 201 earthquakes ranging in seismic moment from 7 1023 to 3 1027 dyne cm the wide dynamic range of the sro asro stations allows us to investigate using the same algorithm series of events among which the smallest and the largest may differ in moment by a factor as large as 1000 among the events studied is a particularly interesting series in january 1981 off the island of honshu the main shock was preceded by three foreshocks and followed by four aftershocks all falling within the range of our analysis there is an indication that the source mechanism changes with the size of the event statistical analysis of the results for all earthquakes reveals that the half duration of shallow and intermediate events is approximated by 1 6 10 8 m01 3 the shifts in origin time for deep focus earthquakes are indicative of the general complexity of these events which depends only weakly on the seismic moment the extreme departures from a double couple mechanism seem to depend both on the moment and on the focal depth while for shallow earthquakes these departures decrease from a maximum at about 1025 dyne cm with increasing moment the reverse appears to be true with respect to deep focus earthquakes shallow earthquakes north of new guinea and along the solomon islands show systematic and substantial departures from the double couple mechanism

fault analysis and paleostress evolution in large strain regions methodological and geological discussion of the southeastern himalayan fold and thrust belt in pakistan abstract we document the structure and kinematics of the southeastern part of the fold and thrust belt of the pakistani himalaya field analysis documents the importance of strike slip faulting associated with folding accordingly a transpression regime is inferred to be responsible for variable amounts of shortening from fault block to fault block the analysis of fault populations that affect the mesozoic to early miocene sediments allows distinguishing two paleostress tensor directions a dominant nw se compression and a minor e w compression are compatible with buckling around the n s axis of the near by hazara kashmir syntaxis from the lack of both systematic overprinting relationships and spatial trend the two tensors were obtained at different locations we conclude that in each location any of these two shortening directions can dominate the distribution of the paleostress tensors substantiates a transpressional regime due to far field himalayan compression and a lateral escape component of the allochthonous fold and thrust belt away from the growing hazara kashmir anticline

influence of small scale fluvial architecture on co 2 trapping processes in deep brine reservoirs a number of important candidate co2 reservoirs exhibit sedimentary architecture reflecting fluvial deposition recent studies have led to new conceptual and quantitative models for sedimentary architecture in fluvial deposits over a range of scales that are relevant to co2 injection and storage we used a geocellular modeling approach to represent this multiscaled and hierarchical sedimentary architecture with this model we investigated the dynamics of co2 plumes during and after injection in such reservoirs the physical mechanism of co2 trapping by capillary trapping incorporates a number of related processes i e residual trapping trapping due to hysteresis of the relative permeability and trapping due to hysteresis of the capillary pressure additionally co2 may be trapped due to differences in capillary entry pressure for different textural sedimentary facies e g coarser grained versus finer grained cross sets the amount of co2 trapped by these processes depends upon a complex system of nonlinear and hysteretic characteristic relationships including how relative permeability and capillary pressure vary with brine and co2 saturation the results strongly suggest that representing small scale features decimeter to meter including their organization within a hierarchy of larger scale features and representing their differences in characteristic relationships can all be critical to understanding trapping processes in some important candidate co2 reservoirs

characterizing flow behavior for gas injection relative permeability of co2 brine and n2 water in heterogeneous rocks we provide a comprehensive experimental study of steady state drainage relative permeability curves with co2 brine and n2 deionized water on a single bentheimer sandstone core with a simple two layer heterogeneity we demonstrate that if measured in the viscous limit relative permeability is invariant with changing reservoir conditions and is consistent with the continuum scale multiphase flow theory for water wet systems furthermore we show that under capillary limited conditions the co2 brine system is very sensitive to heterogeneity in capillary pressure and by performing core floods under capillary limited conditions we produce effective relative permeability curves that are flow rate and fluid parameter dependent we suggest that the major uncertainty in past observations of co2 brine relative permeability curves is due to the interaction of co2 flow with pore space heterogeneity under capillary limited conditions and is not due to the effects of changing reservoir conditions we show that the appropriate conditions for measuring intrinsic or effective relative permeability curves can be selected simply by scaling the driving force for flow by a quantification of capillary heterogeneity measuring one or two effective curves on a core with capillary heterogeneity that is representative of the reservoir will be sufficient for reservoir simulation

stochastic analysis of unsaturated flow in heterogeneous soils 3 observations and applications results of stochastic theory for flow in heterogeneous soils are analyzed by comparisons with laboratory experiments and field observations and through applications examples the two key theoretical results are 1 the variability of capillary pressure or moisture content increases when mean capillary pressure increases and 2 the anisotropy ratio horizontal vertical of effective mean unsaturated hydraulic conductivity increases when mean capillary pressure increases or mean moisture content decreases comparisons with the field data on moisture content and capillary pressure variability show trends similar to those predicted by the theory calculations of hydraulic conductivity anisotropy based on two actual soils show that the variations in soil texture produce large changes in anisotropy as the mean capillary pressure changes several previously reported field observations and laboratory experiments support the theoretical finding of a capillary pressure dependent hydraulic anisotropy for unsaturated flow the importance of this anisotropy effect in applications involving groundwater recharge irrigation surface runoff generation and waste isolation is discussed

sequential vein growth with fault displacement an example from the austin chalk formation texas to determine the opening and precipitation history and characteristics of vein forming fluids analyses of oxygen and carbon isotopes and trace elements were carried out on multilayered crack seal calcite veins in the austin chalk formation near san antonio texas the veins developed within the normal fault zones possessing unique chemical and textural characteristics which indicate sequential vein development they are composed of alternating millimeter to submillimeter thick calcite veinlets and host lithons occasionally crosscut by coarse equant grained secondary calcite veins regular changes in 18o e g 2 6 to 5 6 pee dee belemnite pdb of the calcite veinlets along the length of veins suggest that the individual calcite veinlets were sequentially developed a systematic 18o decrease in the vein opening direction primarily resulted from a continuous increase in temperature of the ascending fluids delivered to the austin chalk relatively constant 13c approximately 1 4 0 4 pdb for the multilayered veins and most secondary veins indicates that the composition of fluids from which the calcite veins precipitated was initially buffered by the bulk chalk there is no spatial variation in trace element composition of the calcite veinlets along the length of veins low sr concentrations in both calcite veinlets and secondary veins relative to those of the host chalk reflect a low partition coefficient of sr in calcite during vein formation normal faults in the cretaceous austin chalk were conduits to upwardly mobile vein forming fluids

grace gravity data help constraining seismic models of the 2004 sumatran earthquake 1 the analysis of gravity recovery and climate experiment grace level 2 data time series from the center for space research csr and geoforschungszentrum gfz allows us to extract a new estimate of the co seismic gravity signal due to the 2004 sumatran earthquake owing to compressible self gravitating earth models including sea level feedback in a new self consistent way and designed to compute gravitational perturbations due to volume changes separately we are able to prove that the asymmetry in the co seismic gravity pattern in which the north eastern negative anomaly is twice as large as the south western positive anomaly is not due to the previously overestimated dilatation in the crust the overestimate was due to a large dilatation localized at the fault discontinuity the gravitational effect of which is compensated by an opposite contribution from topography due to the uplifted crust after this localized dilatation is removed we instead predict compression in the footwall and dilatation in the hanging wall the overall anomaly is then mainly due to the additional gravitational effects of the ocean after water is displaced away from the uplifted crust as first indicated by de linage et al 2009 we also detail the differences between compressible and incompressible material properties by focusing on the most robust estimates from grace data consisting of the peak to peak gravity anomaly and an asymmetry coefficient that is given by the ratio of the negative gravity anomaly over the positive anomaly we show that they are quite sensitive to seismic source depths and dip angles this allows us to exploit space gravity data for the first time to help constraining centroid momentum tensor cmt source analyses of the 2004 sumatran earthquake and to conclude that the seismic moment has been released mainly in the lower crust rather than the lithospheric mantle thus grace data and cmt source analyses as well as geodetic slip distributions aided by gps complement each other for a robust inference of the seismic source of large earthquakes particular care is devoted to the spatial filtering of the gravity anomalies estimated both from observations and models to make their comparison significant

analysis of shallow and deep earthquake doublets in the fiji tonga kermadec region for the fiji tonga kermadec area and for the period from january 1977 to july 2003 the harvard cmt catalogue lists 1022 shallow 410 intermediate and 633 deep earthquakes of moment magnitude from 4 9 to 8 0 the magnitude threshold above which the catalogue is complete is 5 3 5 4 and the number of earthquakes of magnitude above this value is 691 for shallow 329 for intermediate and 476 for deep events respectively the proportion of earthquakes associated with doublets and multiplets against the total number of earthquakes is approximately the same in both data sets and therefore all earthquake pairs were considered regardless of their magnitude we investigated all the pairs of earthquakes that occurred at a centroid distance of less than 40 60 or 90 km from each other and within a time interval of 200 300 or 450 days depending on their magnitude we found 208 pairs of shallow 31 of intermediate and 92 of deep events to ascertain whether these earthquakes in pairs are not connected by chance the possibility of their occurrence in an uncorrelated poissonian catalogue was considered it was assumed that in such a catalogue the inter event time is exponentially distributed the earthquake magnitude follows the gutenberg richter relation and the distribution of centroid distances between the events in pairs is controlled by its non parametric kernel estimate the probability of the appearance of the observed proportion of doublets of shallow earthquakes in the poissonian catalogue was found to be very low the low probability of occurrence in a semi random catalogue created by randomising centroid locations in the actual data set also indicates major importance of the distance criterion used for a doublet specification in general shallow earthquakes tend to form pairs at shorter distances and within shorter time intervals than deep earthquakes both the distance and the time intervals do not depend on the magnitude of involved events the largest number of pairs of deep earthquakes is observed at a depth of about 600 km and the proportion of deep events associated with doublets against the number of all events increases with depth from comparison of the focal mechanism of earthquakes in pairs measured by the 3 d rotation angle it follows that deep earthquakes forming pairs have a more diverse focal mechanism than shallow events the rotation angle for three quarters of shallow pairs and only for about one third of deep pairs is reasonably small the azimuth between two events forming a doublet is in about 60 65 of cases close to the strike of one of nodal planes of the first or the second event

funneled flow mechanisms in a sloping layered soil laboratory investigation artificial capillary barriers are being used to divert water away from sensitive underground regions conversely funneled flow over natural capillary barriers may increase the danger of groundwater contamination by decreasing the travel time and contact area there have been relatively few experimental studies of capillary barrier flow patterns in this study water was applied uniformly across the top surface of a backlit tilting chamber 1 cm thick 110 cm high and 180 cm long in which a coarse sand layer was imbedded in a fine sand bedding slope and water application rates were varied between 0 and 12 and 1 and 3 cm h 1 respectively after attaining steady state matric potential was measured along the textural interface and photos of dye traces were taken in order to visualize streamlines the funneled flow was characterized by three discrete regions an initial capillary diversion a breakthrough region and a toe diversion the breakthrough region consisted of a significant zone of partial breakthrough where the vertical flux into the coarse layer was less than the water application rate the lateral distance of the capillary diversion was explained well by previously published relationships when the water entry value at the textural interface was replaced by lower observed matric potential at which breakthrough occurred at the most upslope point the length of the capillary diversion was overpredicted using the air entry value finally the toe of the coarse layer had significant observed effects on funneled flow patterns which have previously received little if any attention the results of this study imply that the slope of the coarse layer and infiltration rate will largely govern the effectiveness of capillary barriers and that capillary barriers are less effective than previously assumed

paleostress regimes from brittle structures of the karakoram kohistan suture zone and surrounding areas of nw pakistan paleostress orientations were calculated from fault populations at 24 sites along the sw ne segment and five sites along the e w yasin segment of the karakoram kohistan suture zone in nw pakistan they demonstrate the importance of combined thrusting and strike slip faulting however several paleostress tensor directions are distinguished a dominant nw se compression and a minor e w compression are compatible with the recent evolution of this part of the hindu kush from the lack of both systematic overprinting relationships and spatial trend the two tensors were obtained at different locations we conclude that in each location any of these two shortening directions can dominate heterogeneously distributed extension is found in some places and is likely due to local conditions these paleostress tensors substantiate a transpressional regime due to far field himalayan compression and document the long term background of the seismogenic deformation in this region

digital rendering of sedimentary relief peels implications for clastic facies characterization and fluid flow abstract a new technique is presented for generating high resolution digital models of natural sedimentary deposits for quantitative analyses the traditional technique of 2d sedimentary relief peels of unconsolidated clastic deposits is combined with modern digital laser scanning and 3d microscopy techniques to represent spatially varying rock properties related to sedimentary fabrics at native resolution millimeter to meter scale peel topography relief is documented to correlate with changes in mean grain diameter and standard deviation so that the topography can be used as a proxy inferred for spatially varying rock properties related to grain sizes and sorting e g permeability threshold pressure to provide an applied example of the value of such investigation and to illustrate the influence that sedimentary structures can have on fluid migration peel topography is used to populate a threshold pressure 2d continuum for invasion percolation ip simulations ip is typically used for hydrocarbon migration and is being explored to investigate co2 migration in sequestration contexts simulation results for a 3 1 million cell model 0 5 0 25 m of a ripple laminated peel from a modern fluvial point bar suggest that sedimentary fabrics can strongly modify saturation via local capillary trapping the technique datasets and analysis presented are broadly applicable and expand quantitative characterization capabilities for a variety of geologic studies

mississippi valley type mineralization in the silurian paleoaquifer central appalachians this study used lead and sulfur isotope tracers to determine the nature and geometry of mvt related brine flow in the silurian paleoaquifer of the central appalachians although the stratigraphy and lithology of this sedimentary package is similar to that of the important lower cambrian mvt hosting paleoaquifer of the southern appalachians it lacks important mineralization lead isotope compositions from mvt deposits in the lockport dolomite in the upper part of the silurian paleoaquifer form a cluster at about 206pb204pb 18 3 207pb204pb 15 6 and 208pb204pb 38 2 which is similar in form but slightly different in composition from those seen in deposits in underlying clastic rocks sulfur isotope compositions for lockport mvt sulfides range from 19 to 6 and have lower 34s values than mvt sulfides hosted by underlying clastic rocks these relations in combination with na cl br compositions of fluid inclusion leachates suggest that mvt deposits in the lower part of the paleoaquifer formed when rising metal bearing brines intersected reduced sulfur of probable thermogenic origin whereas deposits in the upper part of the paleoaquifer lockport dolomite formed where metal bearing brines intersected reduced sulfur of biogenic origin that was dissolved from sulfate evaporites in the overlying salina group and transported downward into the lockport

sensitivity of stream aquifer seepage to spatial variability of the saturated hydraulic conductivity of the aquifer abstract in this paper the sensitivities of stream aquifer seepage flow and the state of connection or disconnection between stream and aquifer to spatial variability in the aquifer saturated hydraulic conductivity are studied with the variably saturated modelling programme swms 2d using a monte carlo technique a simple stream aquifer flow system is used with a rectangular stream with a clogging layer on its perimeter partially penetrating an alluvial aquifer a 2d nearest neighbour method is used to generate fields of log normally distributed saturated conductivity for the alluvial aquifer for a specific set of degree of heterogeneity and the nearest neighbour autoregressive parameters seven different cases are studied five of these investigate the effect of the nearest neighbour parameters and three cases investigate the effect of aquifer water table level the results show that the nearest neighbour parameters and the aquifer degree of heterogeneity significantly affect the modelling of stream seepage pressure heads and the state of connection disconnection between stream and aquifer particularly when the water table is some distance below the streambed moreover comparisons of these results with a purely deterministic model show good agreement when the stream and the aquifer are connected or disconnected but with a high water table however there are significant differences between the deterministic and stochastic models when the water table is well below the streambed