three dimensional analysis of the capture of contaminated leachate by fully penetrating partially penetrating and horizontal wells the capture of a contaminated leachate by wells is examined for a fully penetrating well a partially penetrating well series of partially penetrating wells and a horizontal well the capture zones for these wells are illustrated in figures charts are used to analyze the minimum pumping rates required to capture a contaminated leachate over a range of aquifer parameters it is shown that fully penetrating and partially penetrating wells have the same minimum pumping rates when the ratio of the aquifer thickness to the size of the contaminated region is 0 5 a partially penetrating well has a much lower pumping rate a horizontal well that is oriented perpendicularly to flow has the lowest pumping rate this well can capture a contaminant with a pumping rate of 1 5 2 times the contaminated discharge

late stage dolomitization of the lower ordovician ellenburger group west texas abstract petrography of the lower ordovician ellenburger group both in deeply buried subsurface cores and in outcrops which have never been deeply buried documents live generations of dolomite three generations of microquartz chert and one generation of megaquartz regional periods of karstification serve to subdivide the dolomite into early stage which predates pre middle ordovician karstification and late stage which postdates pre middle ordovician karstification and predates pre permian karstification approximately 10 of the dolomite in the ellenburger group is late stage the earliest generation of late stage dolomite dolomite l1 is interpreted as a precursor to regional dolomite l2 l1 has been replaced by l2 and has similar trace element o c and sr isotopic signatures and similar cathodoluminescence and backscattered electron images it is possible to differentiate l1 from l2 only where cross cutting relationships with chert are observed replacement dolomite l2 is associated with the grainstone subarkose and mixed carbonate siliciclastic facies and with karst breccias the distribution of l2 is related to porosity and permeability which focused the flow of reactive fluids within the ellenburger fluid inclusion data from megaquartz interpreted to be cogenetic with dolomite l2 yield a mean temperature of homogenization of 85 6 c on the basis of temperature 18owater plots temperatures of dolomitization ranged from approximately 60 to 110 c given estimates of maximum burial of the ellenburger group these temperatures cannot be due to burial alone and are interpreted to be the result of migration of hot fluids into the a ea a contour map of 18o from replacement dolomite l2 suggests a regional trend consistent with derivation of fluids from the ouachita orogenic belt the timing and direction of fluid migration associated with the ouachita orogeny are consistent with the timing and distribution of late stage dolomite post dating dolomite l2 are two generations of dolomite cement c1 and c2 that are most abundant in karst breccias and are also associated with fractures subarkoses and grainstones 87sr 86sr data from l2 c1 and c2 suggest rock buffering relative to sr within dolomite l2 and a retention of a lower ordovician seawater signature while cements c1 and c2 became increasingly radiogenic it is hypothesized that reactive fluids were pennsylvanian pore fluids derived from basinal siliciclastics the precipitating fluid evolved relative to 87sr 86sr from an initial pennsylvanian seawater signature to radiogenic values this evolution is due to increasing temperature and a concomitant evolution in pore water geochemistry in the dominantly silic clastic pennsylvanian section a possible source of mg for late stage dolomite is interpreted to be from the dissolution of early stage dolomite by reactive basinal fluids

analysis of local seismic waveforms from underground nuclear explosions forward modeling for effective source functions at pahute mesa in this study we use forward modeling of surface particle velocity data recorded within 15 km of underground nuclear explosions at pahute mesa in the nevada test site a plane layered velocity structure model is developed and effective source functions are obtained for six events with yields of 155 1300 kt kilotons recorded at ranges presumed to be well outside the zone of inelastic deformation we then use the effective source functions determined from well outside the elastic radius to compute synthetic seismograms for comparison with recordings within the spall zone prior to the onset of spall the comparison is good enabling us to estimate effective source functions for two additional events for which only recordings from the spall zone are available as surface zero is approached however the first half cycle of the observed velocity records includes an inflection which appears as a shoulder in acceleration records this suggests that in addition to the elastic arrival we are seeing secondary arrivals due to spall opening or inelastic shock wave propagation elastic wave propagation predicts the observed peak velocities well beyond a scaled slant range of about 175 m kt but overpredicts the first phase at closer ranges this limit of applicability of elastic wave propagation provides a useful estimate of the elastic radius for pahute mesa explosions yield scaling relations are determined using three events of known yield and these are then used to estimate yields for the eight pahute mesa explosions modeled in this study finally implications for the attenuation of teleseismic body waves are discussed

comparing a three dimensional and a dupuit forchheimer solution for a circular recharge area in a confined aquifer abstract an exact closed form analytic solution is presented for three dimensional steady state flow due to a source disc the solution is used to model a circular recharge area at the upper boundary of a confined aquifer streamlines and contour plots of equipotentials are compared with those obtained from a dupuit forchheimer solution the latter solution is approximate in that resistance to vertical flow is ignored as a further illustration a groundwater contamination problem is solved that of a leaching circular pond in a uniform flow field some streamlines and the shape of the downstream plume are plotted for both the three dimensional and the dupuit forchheimer solution it appears that when the recharge area is sufficiently large the dupuit forchheimer solution is quite adequate particularly when tracing streamlines the results therefore confirm the validity of the dupuit forchheimer assumption when modeling regional flow even under circumstances of areal recharge however when the size of the recharge area is in the order of the aquifer thickness a truly three dimensional solution is needed

effects of source rdp models and near source propagation implication for seismic yield estimation ithas proven difficult to uniquely untangle the source and propagation effects on the observed seismic data from underground nuclear explosions even when large quantities of near source broadband data are available for analysis this leads to uncertainties in our ability to quantify the nuclear seismic source function and consequently the accuracy of seismic yield estimates for underground explosions extensive deterministic modeling analyses of the seismic data recorded from underground explosions at a variety of test sites have been conducted over the years and the results of these studies suggest that variations in the seismic source characteristics between test sites may be contributing to the observed differences in the magnitude yield relations applicable at those sites this contributes to our uncertainty in the determination of seismic yield estimates for explosions at previously uncalibrated test sites in this paper we review issues involving the relationship of nevada test site nts source scaling laws to those at other sites the joint verification experiment jve indicates that a magnitude m b bias 6m b exists between the semipalatinsk test site sts in the former soviet union fsu and the nevada test site nts in the united states generally thissmbis attributed to differential attenuation in the upper mantle beneath the two test sites this assumption results in rather large estimates of yield for largem b tunnel shots at novaya zemlya a re examination of the us testing experiments suggests that thissm b bias can partly be explained by anomalous nts pahute source characteristics this interpretation is based on the modeling of us events at a number of test sites using a modified haskell source description we investigated the influence of the source reduced displacement potential rdp parameters lkand bby fitting short and long period data simultaneously including the near field body and surface waves in general estimates of band kare based on the initial p wave pulse which various numerical analyses show to be least affected by variations in near source path effects the corner frequency parameter kis 20 lower at nts pahute than at other sites implying larger effective source radii the overshoot parameter bappears to be low at nts although variable relative to other sites and is probably due to variations in source conditions for a low b the near field data require a higher value of to match the long period m s and short periodmbobservations this flexibility in modeling proves useful in comparing released fsu yields against predictions based onm b andm s

geochemical and isotopic constraints on the diagenetic history of a massive stratal late cambrian royer dolomite lower arbuckle group slick hills sw oklahoma usa abstract the diagenetic history of the late cambrian massive royer dolomite from the lower arbuckle group slick hills sw oklahoma usa has been evaluated through comprehensive geochemical analyses the dolomite probably formed during early diagenesis from contemporaneous late cambrian seawater evidenced by similar 87 sr 86 sr ratios from 0 70891 to 0 70913 of most 70 dolomite samples to coeval late cambrian seawater from 0 7089 to 0 7092 very light 18o values 10 2 to 12 9 pdb however indicate that the dolomite was significantly modified during burial correlation of various geochemical parameters sr fe 18o and 87 sr 86 sr demonstrates that dolomite samples with increased modification are characterized by lower sr and higher fe concentrations lighter 18o values and less radiogenic 87 sr 86 sr ratios this correlation coupled with the light 18o values of the dolomite demonstrates that meteoric water recharged into overlying carbonates was responsible for burial modification of the dolomite geochemical comparison of the dolomite with associated limestone and quantitative modelling of 18o sr and 87 sr 86 sr variation during water rock interaction suggest that the dolomite underwent long lasting modification the timing of meteoric modification was coincident with the development of regional overlying unconformities corresponding to emergence of the carbonate platform similar diagenetic modification has probably been responsible for 18o depletion and trace element modification of ancient dolomites in many other areas although many of these dolomites have been interpreted to have formed either in mixing zone environments or in subsurface environments

flow to a horizontal well in an aquitard aquifer system a horizontal well is sometime installed in an aquifer beneath a water reservoir to get significant amount of groundwater with better quality an aquitard often separates the surface water body from the underneath aquifer previous studies in vertical wells related to this subject treated leakage from the aquitard as a volumetric source term in the governing equation of flow in the main aquifer a hypothesis termed hantush s approximation for partially penetrating wells in this study flow in the aquitard and aquifer is treated as two systems which are linked through the continuity of flux and head at the aquitard aquifer boundary in particular we treat leakage as a boundary at the aquitard aquifer interface not as a volumetric source the leakage induced by the pumping horizontal well depends on several parameters such as the aquitard thickness the vertical hydraulic conductivity of the aquitard the aquitard specific storage the well location and the well length in general we find that the solution based on the hantush s approximation to some extent deviates from that obtained based on the actual scenario of leakage through the interface during the transient flow condition particularly at the early time for steady state flow the hantush s approximation works reasonably well under realistic conditions of aquitard thickness and hydraulic conductivity as long as the aquitard thickness is relatively thick aquitard aquifer ratio greater than 0 001 this approximation also works reasonably well under realistic horizontal well length and well location as long as the well is not too close to the aquitard aquifer boundary q 2005 elsevier b v all rights reserved

simulation of topographic effects on seismic waves from shallow explosions near the north korean nuclear test site with emphasis on shear wave generation 1 we performed high resolution 8 hz three dimensional simulations of ground motions from shallow explosions in the presence of rough surface topography near the north korean nuclear test site to study elastic propagation effects with emphasis on theoretical aspects of shear wave generation interaction with rough topography causes significant p to rg scattering along the surface with amplification of high frequency 2 8 hz shear waves relative to the flat earth case shear waves of different polarizations are coupled by topographic scattering rg precursors composed of p to rg conversions traveling as surface waves have the spectral amplitudes comparable to the p wave while the rg phase has the low frequency 0 5 3 hz spectral shape of the rg from the flat case plus the high frequency 3 8 hz p wave spectra motions at near vertical takeoff angles corresponding to teleseismic propagation are increased or decreased indicating that waves are focused or defocused by topographic features above the source topographic roughness has a dramatic effect as short wavelength features 2 5 km are included higher frequencies are amplified by topography including frequencies corresponding to wavelengths shorter than the shortest topographic scale length overall topography enhances energy propagating along the surface near the source amplifies surface waves and tends to balance sv and sh polarized motions all of which impact shear wave observations used for nuclear explosion monitoring further simulation studies could elucidate how the wavefield emerging from a topographically rough area ultimately propagates to regional and or teleseismic distances

modified frequency wavenumber algorithm for regional seismograms using filon s quadrature modelling of lg waves in eastern north america summary the main focus of this study is to develop an efficient frequency wavenumber code to synthesize high frequency say 10 hz regional seismograms up to a distance of more than 1000 km in a medium consisting of a large number of crustal layers and investigate effects of regional waveguides on lg waves in this newly developed code the frequency wavenumber response is evaluated by using the filon s quadrature at high frequency and the polynomial approximation of bessei s functions implementing trapezoidal integration at low frequency this has reduced the computation time by several folds compared to the time needed for the trapezoidal integration using this algorithm both broad band seismograms at harvard and short period ectn eastern canadian telemetered network seismograms from 1988 november 25 saguenay earthquake were successfully modelled a moment magnitude of 5 9 was used initially an average waveguide was calibrated to successfully excite the regional pnl and snl waves at hrv its near surface structure constrained by matching the recorded frequency content the crust mantle transition zone was constrained by modelling the strength of the broad band snl waves consisting of sn ssmsnsmssms and ssmssms phases relative to the initial pnl waves the model was modified to consist of thin layers with an alternating high and low velocity distribution to match the high frequency ectn lg waves observed from 300 to 600 km away in addition the effect of a near surface irregular receiver structure on the duration of lg waves was also investigated by convolving its response with the regional lg seismograms initial study suggests this method as viable for modelling the entire lg waves including the coda numerical studies suggest that the shapes and peak amplitudes on lg seismograms depend more strongly on the source depth anelasticity and crustal waveguide than do the pnl seismograms

a procedure for modelling shallow dislocation sources summary expressions for displacements on the surface of a layered half space due to an arbitrary oriented shear dislocation are given in terms of generalized ray expansions useful approximations of these expressions for shallow events as recorded at teleseismic distances for realistic earth models are presented the results of this procedure are used to generate synthetic p sv and sh waveforms for various assumptions of stress drop

modern marine dolomite cement in a north jamaican fringing reef minor quantities of ordered dolomite delta sup 18 o 2 0 per thousand pdb composition ca sub 1 22 mg sub 0 78 co sub 3 sub 2 have formed from near normal seawater in a subtidal hardground as part of a modern fringing coral reef crystals 5 mu m in diameter precipitated within the past 1 8 ka in the form of syntaxial fringes on mg calcite marine cements and skeletal allochems the crystals have a fine modulated microstructure and c reflections both apparently formed during crystal growth

gaining and losing sections of horizontal wells the flux along a horizontal well in uniform flow is examined using an analytic three dimensional steady model wells with uniform head and low pumping rates have gaining sections along which water enters the well and losing sections along which water exits such a well may provide a conduit for contaminated groundwater to be drawn into the well conveyed a large distance and injected into an uncontaminated region of an aquifer dimensionless ratios of the well s length l and radius r aquifer thickness h and uniform flow rate u are developed to quantify the minimum pumping rate qmin at which no losing section occurs the ratio qmin ulh is presented as a nomograph usingr h and l h for placement parallel to flow and is 6 r h for placement perpendicular to flow and a parabolic relationship between these limiting cases is developed for placement oblique to flow capture zone geometry is quantified using qmin ulh

evidence for a relationship between hydrocarbons and authigenic magnetite establishing a relationship between hydrocarbon migration and the precipitation of authigenic magnetite in sedimentary rocks is of significant interest with respect to 1 elucidating mechanisms for remagnetization and establishing the origin of secondary magnetizations residing in magnetite 2 developing a method to date hydrocarbon migration events by determining the time of remanence acquisition by palaeomagnetic methods and 3 evaluating whether searching for anomalous concentrations of diagenetic magnetic minerals and or aeromagnetic anomalies is justified as a relatively inexpensive exploration tool the direct association of hydrocarbon migration and the precipitation of authigenic magnetite has however not been established in this paper we report palaeomagnetic rock magnetic petrographic and geochemical results of a study of samples from permian spelebthems and gilsonite found in the ordovician arbuckle group in southern oklahoma the results indicate that there is a genetic relationship between hydrocarbon migration and the precipitation of authigenic magnetite

multiple phase fracture and fault controlled burial dolomitization upper devonian wabamun group alberta abstract recent data from the subsurface tangent eaglesham and normandville fields located east of the peace river arch in northern alberta indicate that these wabamun group subtidal carbonates have undergone a complex diagenetic history related to multiple stages of fracturing and faulting burial dolomitization which generated mainly matrix dolomites was responsible for the development of porous reservoir rocks which are spatially highly variable primary porosity was reduced by marine and early burial diagenesis which formed micrite syntaxial overgrowths granular blocky and coarse fracture filling calcite cements minor amounts of microdolomite and floating dolomite rhombs formed during shallow burial further porosity reduction by mechanical compaction and cementation except for minor dissolution and initial fracturing resulted in predominantly tight limestones matrix dolomitization is associated with the second most extensive phase of fracturing which greatly increased both the porosity and permeability of the tightly cemented wabamun limestones dolostones which comprise 85 matrix dolomite are the principal reservoir rock but have highly variable porosity large dissolution cavities developed locally after formation of the matrix dolomites the third phase of fracturing crosscuts the matrix dolomites in the tangent field these fractures locally form irregular cavity systems which are partly filled with finely crystalline and saddle dolomites these fine crystalline dolomites probably represent dolomite silt and sand derived from brecciation of the earlier matrix dolomite during faulting renewed faulting was responsible for rotation of breccia clasts saddle dolomite was precipitated during at least two phases on the sides and undersides of some clasts and in fractures late stage bladed anhydrites and fracture filling coarse calcites precipitated during hydrocarbon generation presumably in the late cretaceous except locally where source rocks may have been heated by ascending hot brines the timing of dolomitization and fracturing is difficult to determine early fractures most likely occurred in the late devonian to early carboniferous during early burial and mechanical compaction the second phase of fracturing probably occurred during the mississippian to pennsylvanian when the normandville and dunvegan faults underwent movement during the foundering of the peace river arch the third phase of fracturing is linked to the more rapid subsidence and burial by the cretaceous and early tertiary clastic wedge which presumably reactivated some of the earlier faults the combined stratigraphic petrophysical and geochemical data support the following interpretations 1 early dolomite rhombs and patches resulted from the movement of seawater through semi lithified sediment near the sediment water interface or during early compaction 2 matrix dolomites formed at temperatures of between 40 and 65 c and depths of about 500 to 1500 m probable fluid sources for matrix dolomites were devonian brines buried with these and underlying sediments and expelled by mechanical compaction possibly aided by seismic pumping along stage ii fracture fault conduits 3 sucrosic saddle and reworked dolomites postdate stage iii fractures and occurred during deep burial most saddle dolomites formed at temperatures around 100 c but a few formed near 200dc these dolomites formed from warm highly saline basin brines and or from hot brines that ascended along fractures and faults and other stratigraphic conduits from deeper parts of the basin and or the crystalline basement

dolomitization of holocene mg calcite supratidal deposits ambergris cay belize dolomitized crusts and associated sediments 845 2925 yr old on ambergris cay belize central america compose a significant portion of the holocene sediment section on many supratidal flats the dolomitic sections are as thick as 0 7 m and contain an average of 70 calcic dolomite dolomite occurs as a replacement of high mg calcite micrite matrix and allochems and as passively precipitated cements isotopic analyses suggest that dolomitization appears to be promoted primarily by reactions of the magnesian calcite supratidal sediments with essentially near normal marine waters the effects of seasonal influxes of meteoric and hybrid fluids however are also clearly evident in the crusts as indicated by isotopes dolomite crystal etching the selective leaching of aragonite and the local loss of mg 2 from the host micrite and included skeletal fragments the amounts rapid rates of dolomitization and initial mg calcite mineralogy of the sediments make the ambergris cay supratidal flats exceptional in the holocene and this area may be a model for the genesis of some ancient peritidal dolomites

estimating the relative yields of novaya zemlya tests by waveform intercorrelation summary the relative size of 15 underground nuclear explosions at the novaya zemlya test site is determined by applying a relative waveform analysis called intercorrelation to 566 teleseismic short period p waves the waveforms are corrected for the effects of pp interference and yield scaling of the explosion source functions so that signals from different events recorded at the same station can be analytically compared for events within a single test site this procedure accounts for common path and receiver effects relative explosion source strengths in the 0 5 2 0 hz frequency band determined by intercorrelation are consistent with the results of conventional mb analysis absolute yield estimates from both intercorrelation and mb analyses have much greater uncertainty due to unknown baselines the yield estimates for the 15 events range from 36 to 3886 kt assuming that te 0 5 s and that yield scaling relations for the amchitka test site are appropriate for novaya zemlya the pp delay times obtained from intercorrelation of novaya zemlya events are similar to the delay times for amchitka events with equivalent yields consistent with both being hardrock sites the analytical waveform comparisons also provide criteria for identifying anomalous events the novaya zemlya test site has two subsites separated by about 300 km one of the 11 events in the northern subsite and one of the four events in the southern sub site have anomalous waveforms a waveform modelling study indicates that the anomalous southern event was a double explosion northern and southern novaya zemlya have different waveform and amplitude patterns apparently caused by different focusing and defocusing of seismic energy by laterally varying structure near the sources

modeling near field and teleseismic observations from the amchitka test site during the amchitka testing program recordings were made of the near field ground velocity for events milrow and cannikin these records exhibited a p arrival a feature associated with near field pp and a developing rayleigh wave in this investigation simple models were found which match the complete seismograms they simultaneously predict the amplitude wave shape timing and periodicity of both the body waves and the surface waves models for both the amchitka crustal structure and the source time functions were developed the crustal model is similar to previous models in its average properties so travel time constraints are still satisfied small modifications have been made to match the waveform data the events on amchitka can apparently be represented as isotropic point sources with the types of simple source time histories predicted by classical yield scaling laws a source model for event longshot was developed on the basis of the yield scaling laws since no near field records are available for it the source models were tested by comparing the teleseismic body waveforms they predict with observations short period p waves long period p waves and long period ps waves were considered the short period p waves provided the best constraint to match them it was necessary both to develop a model for teleseismic pp since it arrives later than the near field model would predict and to estimate the average value of t the milrow and cannikin teleseismic short period p waves indicate that the average effective t for teleseismic ray paths from amchitka is 0 9 s the scatter about this value however is very substantial the accuracy of the scaling laws was tested by comparing synthetics for longshot to teleseismic observations the predicted amplitudes and wave shapes fall within the scatter in the observations though again this scatter is substantial

estimating explosion yield by analytical waveform comparison summary the yields of 28 underground nuclear explosions at nts 25 on pahute mesa are estimated by applying a relative waveform analysis called intercorrelation to 1256 teleseismic short period p waves recorded at 74 wwssn and csn stations corrections for the effects of pp interference and yield scaling of the explosion source functions are determined and applied to the waveforms enabling analytical comparison of signals from events with different yields and burial depths the procedure accounts for common receiver and propagation effects relative explosion source strengths in the 0 5 2 0 hz frequency band are determined with results of near field modelling of strong ground motions establishing the absolute source spectral levels four events with detailed near field models are used as master events in the intercorrelation process and it is demonstrated that the relative source strengths are better resolved than the absolute values events with announced yields are used to determine empirical relations between yield and source strength which in turn predict the yields of the other events these yield estimates are shown to be comparable with those obtained by standard mb and relative amplitude analysis the analytical waveform comparisons also provide estimates of the pp parameters for each event and criteria for identifying anomalous events such as pipkin and muenster for which the waveforms differ from those of other events in the test site possible mechanisms affecting the anomalous events are considered pahute mesa is shown to be a distinct subsite within nts with different teleseismic amplitude and waveform variations than observed at other subsites

the effect of intra wellbore head losses in a vertical well abstract flow to a partially penetrating vertical well is made more complex by intra wellbore losses these are caused not only by the frictional effect but also by the kinematic effect which consists of the accelerational and fluid inflow effects inside a wellbore existing models of flow to a partially penetrating vertical well assume either a uniform flux boundary condition ufbc or a uniform head boundary condition uhbc for treating the flow into the wellbore neither approach considers intra wellbore losses in this study a new general solution named the mixed type boundary condition mtbc solution is introduced to include intra wellbore losses it is developed from the existing solutions using a hybrid analytical numerical method the mtbc solution is capable of modeling various types of aquifer tests constant head tests constant rate tests and slug tests for partially or fully penetrating vertical wells in confined aquifers results show that intra wellbore losses both frictional and kinematic can be significant in the early pumping stage at later pumping times the uhbc solution is adequate because the difference between the mtbc and uhbc solutions becomes negligible

yields of soviet underground nuclear explosions from seismic surface waves compliance with the threshold test ban treaty abstract magnitudes of the larger soviet underground nuclear weapons tests from the start of the threshold test ban treaty in 1976 through 1982 are determined for short and long period seismic waves yields are calculated from the surface wave magnitude for those explosions at the eastern kazakh test site that triggered a small to negligible component of tectonic stress and are used to calibrate body wave magnitude yield relationship that can be used to determine the sizes of other explosions at that test site the results confirm that a large bias related to differential attenuation of p waves exists between nevada and central asia the yields of the seven largest soviet explosions are nearly identical and are close to 150 kilotons the limit set by the threshold treaty

analytic element solutions for seepage towards topographic depressions abstract point and line singularities are superposed with incident unidirectional saturated and unsaturated flows the resulting isobars of 3d laplacian or advective dispersion equation fields model either seepage face dimples and rills on a tilted hillslope or an undulated top of the vadose zone above a stagnant water table the reconstructed shapes of isobars are conchoidal i e convex concave all flow characteristics drawdowns velocity and kirchhoff potential distributions dimple sizes are calculated either explicitly or by elementary computer algebra routines

isotopic geochemistry of burial metamorphosed volcanogenic sediments great valley sequence northern california isotopic and mineralogic data from an 8500 m thick section of the great valley sequence northern california indicate that changes in the 18o values of authigenic minerals resulted from the conversion of smectite to a 10 a clay mineral as temperature increased with burial in the jurassic cretaceous outer arc basin the clay mineral assemblage in mudstone is characterized by a proportional increase of the 10 a clay mineral with increasing stratigraphic depth and by a depletion in the 18o value of the mixed layer smectite 10 a clay mineral with descending stratigraphic position from 21 9 to 15 5 smow modeling of the oxygen isotopic data from authigenic phases based on equilibrium fractionation during clay mineral diagenesis indicates that 18o values of calcite in mudstones and of calcite cements in sandstone precipitated along a temperature gradient of about 25 c km during maximum burial to about 6 7 km d values of the mixed layer smectite 10 a clay mineral range between 69 to 44 smow using temperatures calculated from the oxygen isotopic data the deuterium and oxygen isotopic data indicate that the smectite underwent late stage dehydration and probably buffered the composition of formation waters from sea water values to isotopic compositions of 18o 8 smow and d 25 smow the 13c values of calcite from mudstone and sandstone imply that crystallization of authigenic calcite was linked to organic diagenesis during which dissolved hcot 3 was continuously enriched in 13c as temperature increased with burial at the base of the sequence and immediately overlying the ophiolitic basement rocks several hundred meters of strata were altered by more oxygen depleted 18o 4 to 5 hydrothermal fluids emanating from the ophiolitic rocks probably at maximum burial depth

high order line elements in modeling two dimensional groundwater flow this paper presents a new analytic element formulation for high order line elements in modeling two dimensional groundwater flow these elements are line doublets line dipoles and line sinks the jump functions for line elements are expressed as chebyshev series the unknown coefficients are computed by applying the principle of overspecification to the boundary conditions the use of the high order elements and the principle of overspecification have resulted in high precision and significant improvements in computational efficiency compared to the existing collocation based formulation the new formulation is currently being used in the development of the metropolitan area groundwater model for twin cities minnesota usa and for enhancements of the next release of national groundwater model for the netherlands

meteoric modification of early dolomite and late dolomitization by basinal fluids upper arbuckle group slick hills southwestern oklahoma 1 thick massive dolomite units from the upper arbuckle lower ordovician peritidal carbonate sequence slick hills southwestern oklahoma provide insight into two important problems 1 modification of early dolomite and 2 late dolomitization early dolomite volumetrically dominant is nonluminescent to dully luminescent 87 sr 86 sr ratios of most early dolomite samples are similar to both early ordovician seawater and associated limestones consistent with an early origin from coeval seawater all early dolomite samples are characterized by low delta 18 o values 5 1 to 10 0 o oo pdb indicating postdepositional modification meteoric water buffered by younger carbonates with lower 87 sr 86 sr ratios was probably responsible for modification because lower sr concentrations delta 18 o values and 87 sr 86 sr ratios characterize the more intensively modified early dolomite samples meteoric modification probably occurred during emergence of the carbonate platform in the ordovician late dolomite volumetrically minor is brightly luminescent and occurs mainly in transition zones between early dolomite and associated limestone late dolomite has high 87 sr 86 sr ratios delta 18 o values 5 9 to 2 5 o oo pdb and fe and mn concentrations relative to early dolomite and associated limestone 87 sr 18 o fe and mn enriched fluids derived from the anadarko basin during the late paleozoic are proposed to have formed the late dolomite the fluids migrated through preexisting early dolomite aquifers and dolomitized limestones near the early dolomite limestone contacts which existed at that time although early dolomite remained more porous than limestone during early burial burial alteration by solution compaction and cementation by late dolomite have reduced porosity considerably better reservoir quality is expected to be associated with late dolomite in the arbuckle group

hydrodynamics of the capture zone of a partially penetrating well in a confined aquifer in the pump and treat approach to the problem of managing a contaminated aquifer a key problem is to design an effective capture system that collects only the polluted groundwater without allowing any of it to escape at present it is customary to design a capture system using fully penetrating withdrawal wells very often however only part of the vertical thickness of the aquifer is contaminated so the question may arise whether a more efficient capture system can be achieved using partially penetrating wells very little work has been done on the application of partially penetrating wells to this problem a new semianalytic method that can be used in determining the geometry of the capture zone for steady state flow to a partially penetrating well that is screened from the top or from the bottom of a confined aquifer has been developed by combining the velocity potentials for flow to the well with that for the regional flow field a three dimensional velocity potential that can be used in determining the complete geometry of the capture surface has been developed the results have shown that with a constant pumping rate the maximum horizontal extent of the capture surface at the top or bottom of the aquifer increases as the degree of penetration decreases as one would expect the maximum vertical extent increases as the depth of penetration increases thus if one knows the actual location of the contaminant plume an appropriate combination of the degree of penetration and pumping rate can be selected to create an effective capture zone

origin of dolomitization on the barbwire terrace canning basin western australia a thick areally extensive subsurface sequence of upper devonian carbonates occurs on the barbwire terrace in the canning basin of western australia it is a platform sequence in which most of the shallow water lithologies have been thoroughly dolomitized slightly deeper water mark have remained as limestones the major regional dolomite type in the sequence is not restricted to peritidal lithologies and forms large thicknesses of dolomite up to 600 m with no primary calcite a small volume of evaporitic supratidal dolomite is present at one location this dolomite is derived from highly saline fluids developed in an arid supratidal environment replacement dolomite of the regional dolomite type has a xenotopic form with undulose extinction and irregular crystal boundaries in addition saddle dolomite cements appear to have precipitated contemporaneously with the major phase of replacement dolomite this suggests the regional dolomite type was precipitated at slightly elevated temperatures dolomitized stylolites and cements appear to indicate that dolomitization occurred after cementation and pressure solution geochemically the synsedimentary supratidal and regional dolomite types are quite distinctive supratidal dolomites have 6 o values which are significantly higher 6180 2 to i pdb than the regional dolomite type 6l80 9 to 2 pdb assuming the lowest 6 o values for the sabkha dolomite represent replacement in marine waters the oxygen isotopic composition for upper devonian canning basin marine dolomite would be around 6l80 2 pdb the petrographic and geochemical characteristics of the regional dolomite type support a burial diagenetic origin however sources of magnesium in current burial dolomitization models appear insufficient to account for the large volume of dolomite on the barbwire terrace therefore it is suggested that dolomitization may have taken place in a near surface environment with a major recrystallization event superimposed during burial diagenesis

brachiopods as indicators of original isotopic compositions in some paleozoic limestones the original stable isotopic composition of paleozoic marine carbonate rocks is important to establish a baseline for evaluating diagenetic alteration and providing a reliable data base for modeling exogenic geochemical cycles of the elements we have compared the 18 o and 13 c values in the nonluminescent portions of brachiopods with similar published data of whole brachiopods other whole fossils and estimates of original isotopic composition of marine cements the oxygen and carbon isotopic records for each of these paleozoic components show generally good internal consistency significant discrepancies however were noted between results on the different components isotopic and trace element data presented in this study suggest that permo carboniferous whole brachiopods are little altered chemically nonetheless a more reliable but not fool proof approach for obtaining pristine isotopic values is microsampling of least altered regions based on cathodoluminescence in conjunction with staining techniques and elemental analyses the carbon and oxygen isotopic compositions of all components decrease in 18 o and 13 c in geologically older material neither temporal trend is monotonic however oxygen isotopic results suggest an important positive shift in 18 o of about 2 during the early carboniferous whereas the carbon isotope trend shows a major positive shift 2 3 during the mid carboniferous

the δ18o record of phanerozoic abiotic marine calcite cements monomineralic abiotic marine cements formed in low latitude phanerozoic reefs provide the direction and amplitude of secular variation of delta sup 13 c and delta sup 18 o in marine calcite and defines two end member compositions 580 to 360 my minus 7 to minus 5 per thousand delta sup 18 o sub pdb and 360 to present minus 3 to 0 per thousand delta sup 18 o sub pdb sampling of the devono carboniferous transition 375 320 my at several global sites reveals a rapid change in carbonate isotopic compositions bracketed within fammenian to early visean aged strata a 7 to 15 my time interval this shift corresponds to a 2 offset in mean delta sup 13 c and 3 4 offset in delta sup 18 o the abruptness of such change and its overall correlation with variations in sup 87 sr sup 86 sr delta sup 34 s delta sup 13 c and li al ratios in marine sediments suggests a primary offset in marine water composition

variability in explosion body wave magnitudes an analysis of the rulison gasbuggy anomaly an analysis of the rulison gasbuggy mb anomaly is presented which encompasses comparative studies of near regional regional and teleseismic data recorded from these two explosions as well as theoretical simulation analyses of selected near regional and teleseismic data sets previously proposed explanations for this mb anomaly such as differences in explosive source coupling and variations in upper mantle attenuation beneath the two test sites are critically examined and shown to be inconsistent with various aspects of the observed data however both long period and short period evidence is presented which indicates that significant tectonic release accompanied the rulison explosion it is demonstrated that the short period near regional sh observations from rulison can be theoretically explained by an explosion induced tectonic release equivalent to a 250 to 300 bar stress drop at the elastic radius of the explosion the inferred prestress field is homogeneous to first order and oriented as a pure shear on planes dipping at about 45 with normal or dip slip displacements occurring as a consequence of stress relaxation such a tectonic release mechanism would be expected to decrease the associated explosion mb value by more than 0 3 units and therefore can provide a quantitative explanation of the observed rulison gasbuggy mb anomaly we conclude that tectonic release can significantly affect the short period teleseismic p waves from explosions at least in cases where the tectonic stress is large and favorably oriented

reply to comments by a douglas j b young and n s lyman and a note on the revised moments for pahute mesa tectonic release in two earlier papers wallace et al 1983 1985 we discussed the evidence for tectonic release from underground nuclear explosions on pahute mesa at the nevada test site nts as observed in long period body waves it has been shown for some time that the nonisotropic component of the surface waves from most of these events could be explained by an equivalent double couple source namely strike slip motion on north striking faults

the implication of the oxygen isotope records in coexisting cherts and phosphates 18 o values have been determined for 53 coexisting chert phosphate pairs from the phanerozoic and precambrian in addition 18 o values were also determined for 18 biogenic phosphates from the phanerozoic the oxygen isotope data for the chert phosphate pairs permit the calculation of the temperatures of formation of the chert phosphate pairs as well as the 18 o of the waters in which they equilibrated in turn the calculated 18 o of the waters permit the calculation of temperatures from the isotopic data of the biogenic phosphates the temperatures for the tertiary and mesozoic samples are compatible with the literature values determined from oxygen isotope data for well preserved calcareous marine skeletal remains the temperatures calculated from the chert phosphate pairs of the paleozoic are usually higher and vary in cycles of about a 150 million year period the early precambrian temperatures are as high as 80 c and decrease with time the use of chert phosphate pairs for temperature determinations are sufficiently promising to warrant further investigations of this type on well preserved chert phosphate or carbonate phosphate pairs

analytical study of capture time to a horizontal well we have investigated capture time through a horizontal well for several types of aquifers we have studied two scenarios in which wells are at the middle and at the bottom or the top of an aquifer we have obtained the closed form analytical solutions of capture times for these two scenarios in homogeneous confined aquifers for both isotropic and anisotropic cases we have discussed the applicability and the limitation of the analytical solutions the presence of confining boundaries in vertical direction constrains the vertical flow but enhances the horizontal flow the presence of anisotropy with a smaller vertical conductivity further limits the vertical flow and increases the horizontal flow we have conducted numerical simulations to obtain capture times and found that they were very close to the analytical solutions given the same conditions we have further analyzed the advantages and disadvantages of two different methods of simulating a horizontal well uniform flux and uniform head

pervasive subsurface dolomitization of the nisku formation in central alberta abstract the nisku formation in the subsurface of central alberta canada contains pervasive dolomites that occur mainly as a replacement of reefal limestones the degree of pervasive dolomitization increases downdip along a structural homocline from about 25 to 100 vol and associated replacive anhydrites increase from about 5 to 20 vol pervasive dolomites occur as two types one type consists of almost non porous and impermeable mosaics of cloudy crystals that have diameters of 5 300 microns the other type has significant intercrystalline porosity and permeability and consists of cloudy and clear crystals ranging in size from 100 500 microns cathodoluminescence zonation is rare but modulated structures observed with tem are common both types of dolomite have strong xrd ordering refl ctions and are nearly stoichiometric sr concentrations 25 125 ppm increase and mn concentrations 20 400 ppm decrease upwards in several cores the boron contents of both dolomite types 20 50 ppm are enriched relative to other diagenetic phases 18 ppm the sr isotope ratios vary from 0 7089 0 7107 and are enriched relative to devonian and younger seawater oxygen and carbon isotope ratios cluster around 5 8 permil pdb and 2 0 permil pdb respectively and are similar to those of remnant calcites from the combination of stratigraphic petrographic petrophysical and geochemical data it is inferred that both types of matrix dolomite formed contemporaneously from the same fluids in a flow regime with predominantly upward fluid movement at temperatures between about 40 50 c and at burial depths of about 300 1 000 m most anhydrites formed originally as gypsum during the advanced stages and after matrix dolomitization and later recrystallized to the anhydrites now present based on all accumulated data and on mass balance calculations at least two types of subsurface flow could have caused pervasive dolomitization and gypsification anhydritization 1 expulsion of burial compaction water i e chemically modified seawater with or without additional contributions of m bearing formation waters from deeper parts of the basin e g middle devonian brines and 2 thermal convection of formation fluids originally underlying and or overlying the nisku

the origin and evolution of saline formation water lower cretaceous carbonates south central texas u s a abstract land l s and prezbindowski d r 1981 the origin and evolution of saline formation water lower cretaceous carbonates south central texas u s a in w back and r letolle guest editors symposium on geochemistry of groundwater 26th international geological congress j hydrol 54 51ndash 74 systematic chemical variation exists in formation water collected from a dip section through lower cretaceous rocks of south central texas chemical variation can be explained by an interactive water rock diagenetic model the cyclic lower cretaceous shelf carbonates of the edwards group dip into the gulf of mexico coast geosyncline and can be considered to a first approximation as part of a complex aquifer contained by paleozoic basement beneath and by relatively impermeable upper cretaceous clay and chalk above the hydrodynamic character of this carbonate system is strongly controlled by major fault systems major fault systems serve as pathways for vertical movement of basinal brines into the lower cretaceous section formation water movement in this sytem has strong upfault and updip components the parent na ca cl brine originates deep in the gulf of mexico basin at temperatures between 200 and 250 c by the reaction halite detrital plagioclase quartz water albite brine other dissolved components originate by reaction of the fluid with the sedimentary phases k feldspar calcite dolomite anhydrite celestite barite and fluorite significant quantities of pb zn and fe have been mobilized as well as the brine moves updip out of the overpressured deep gulf of mexico basin and encounters limestones of the stuart city reef trend the buried platform margin small amounts of galena precipitate in late fractures continuing to rise upfault and updip the brine becomes progressively diluted on encountering significant quantities of dolomite in the backreef facies the ca rich brine causes dedolomitization although thermochemical consideration suggests that small amounts of several authigenic phases should precipitate most have yet to be found minor amounts of several kinds of calcite spar are present however as the brine evolves by dilution and by cooling no systematic changes in any cation cl ratio occur except for regular updip gain in mg as a result of progressive dedolomitization the formation water highly diluted by meteoric water eventually discharges along faults as hot mineral water

holocene dolomitization of supratidal sediments by active tidal pumping sugarloaf key florida abstract sugarloaf key is an area where holocene dolomitization is occurring calcium rich dolomite is found in a 0 25 to 10 cm thick surface crust which transgresses a thin layer of carbonate mud overlying the karsted pleistocene miami oolite radiocarbon ages of the crust range from 160 years b p to 1420 years b p with a corresponding increase in dolomite content from 0 to 80 the relatively high permeability of the underlying pleistocene oolite and low permeability of the holocene carbonate mud results in a tidal lag between surface water and the partly confined aquifer consequently seawater is pumped upward and downward through the holocene sediment during spring tides the highest concentration of dolomite is found in areas where the sediment layer is thinnest and tidal pumping is most effective limited analyses of surface and subsurface water taken at intervals throughout the pumping cycle suggest that the dolomitizing fluid is essentially florida bay water the earliest diagenesis is caused by precipitation of dolomite cement which occurs as 0 1 to 0 3 micron subrounded crystallites that show no distinct crystal form during further cementation and somewhat later during replacement of preexisting crystallites poorly ordered dolomite forms as 1 to 5 micron euhedral rhombs x ray diffraction data indicate that the crystallized dolomite is better ordered and less calcium rich than the dolomite composed of crystallites

horizontal well hydraulics in leaky aquifers abstract this paper presents a general study of horizontal well hydraulics for three aquifer types a leaky confined aquifer a leaky water table aquifer and a leaky aquifer under a water reservoir semi analytical solutions are obtained for cases that exclude and include the aquitard storage the type curves and derivative type curves for these different conditions are provided a graphically integrated matlab program named hw leak is written to facilitate numerical calculations and generation of the type curves and derivative type curves this study shows that 1 derivative type curves are more sensitive to the aquitard parameters than the type curves and that 2 drawdown is sensitive to the aquitard aquifer thickness ratio and the hydraulic conductivity ratio at the intermediate and later time both curves are less sensitive to the aquitard aquifer specific storage ratio while the degree of sensitivity of the drawdown to the aquitard parameters is high in a leaky confined aquifer moderate in a water table aquifer and low in an aquifer under a water reservoir

numerical analytical interfacing in two dimensions with applications to modeling nts seismograms a new method for interfacing numerical and integral techniques allows greater flexibility in seismic modeling specifically numerical calculations in laterally varying structure are interfaced with analytic methods that enable propagation to great distances such modeling is important for studying situations containing localized complex regions not easily handled by analytic means the calculations involved are entirely two dimensional but the use of an appropriate source in combination with a filter applied to the resulting seismograms produces synthetic seismograms which are point source responses in three dimensions the integral technique is called two dimensional kirchhoff because its form is similar to the classical three dimensional kirchhoff data from yucca flat at the nevada test site are modeled as a demonstration of the usefulness of the new method in this application both local and teleseismic records are modeled simultaneously from the same model with the same finite difference run this application indicates the importance of locally scattered rayleigh waves in the production of teleseismic body wave complexity and coda

modeling teleseismic sv waves from underground explosions with tectonic release results for southern novaya zemlya detailed forward modeling of long period shear waves for two large underground explosions at the southern novaya zemlya test site indicates that the appropriate equivalent double couple orientation for the tectonic release radiation is vertical strike slip previous studies of observed teleseismic sh waveforms and sv amplitudes for the 27 october 1973 and 2 november 1974 events using geometric ray theory could not distinguish between vertical strike slip and 45 dipping thrust geometries either mechanism can match the observed four lobed sh radiation pattern and the two lobed sv amplitude pattern can be produced by interference with an appropriate size explosion ps signal however the complexity of the observed sv waveforms arising from sp conversions near the receiver diffracted sp and shear coupled pl phases is not accounted for in the ray theory synthetics incorporating more realistic green s functions using baag and langston s 1985b wkbj spectral method allows more complete modeling of the sv signals due to differences in frequency content between the explosion and double couple sv waveforms constructive interference occurs more efficiently than destructive interference when the two signals are linearly superimposed as a result using tectonic release moments determined from the sh waves and the optimum f factors required to match the sv amplitude patterns the waveforms produced by the strike slip and thrust orientations differ substantially at some azimuths the strike slip solution yields a consistently superior match to the data using the eu2 model of lerner lam and jordan 1987 for the source region and either eu2 or tna grand and helmberger 1984 for the receiver structure together with an attenuation model similar to sl8 we obtain a double couple moment m 3 2 1024 dyne cm and explosion source strength 3 8 0 5 1011 cm3 for the 27 october 1973 event and m 1 7 1024 dyne cm and 2 0 0 3 1011 cm3 for the 2 november 1974 event complete waveform modeling of sv signals can thus provide improved constraints on tectonic release radiation and explosion source strength

deformation of stream surfaces in steady axisymmetric flow stream surfaces are used to examine the arrangement of neighboring streamlines in steady divergence free axisymmetric flow expressions are obtained that relate the angle of intersection between stream surfaces with general orientations to the stokes stream function and to the specific discharge vector these expressions are used to quantify deformation to the geometry of streamlines and stream surfaces occurring in axisymmetric flow the stokes stream function is presented for an isolated inhomogeneity in hydraulic conductivity with spheroidal geometry it is shown that axisymmetric flow generated by inhomogeneity rearranges the relative position of a streamline with respect to neighboring streamlines only locally in contrast a persistent rearrangement in the orientation and spacing of neighboring streamlines is observed between large distances upgradient and downgradient from groundwater withdrawal this characterizes all possible rearrangement of neighboring streamlines in axisymmetric flow withdrawal or production is required for a persistent rearrangement to occur

strontium isotopic evolution of oil field waters from carbonate reservoir rocks in bindley field central kansas u s a abstract oil field waters produced from mississippian carbonate reservoir rocks in bindley field kansas had an average salinity of about 42 8 mg l they were enriched in ca sr na k rb and li and depleted in mg relative to sea water at the same level of either cl or br concentration the average abundances of different elements are as follows na 13 460 mg l k 325 mg 1 rb 0 9 mg l li 12 mg l ca 1 515 mg l sr 42 mg l mg 430 mg l cl 23 000 mg l so4 2 630 mg l br 32 mg l the 87 sr 86 sr values of the waters ranged between 0 7221 and 0 7230 whereas the values of the host carbonate rocks were between 0 7090 and 0 7093 the very high 87 sr 86 sr values of the waters probably occurred as a result of their reaction with alkali feldspar minerals in buried precambrian crystalline rocks to the east of the bindley field the study demonstrates that despite their residence in carbonate reservoir rocks oil field waters can retain sufficiently distinct isotopic memory that may provide important dues about mineral water interactions in the chemical evolutionary history of the waters the study further indicates that very late diagenetic reactions in many carbonate rocks are of minor extent difference in the sr isotopic data among the oil field waters suggests that the sr isotopic data can be used as a reliable guide in recognising existence of separate pools in an oil field

yields of soviet underground nuclear explosions at novaya zemlya 1964 1976 from seismic body and surface waves abstract surface and body wave magnitudes are determined for 15 u s s r underground nuclear weapons tests conducted at novaya zemlya between 1964 and 1976 and are used to estimate yields these events include the largest underground explosions detonated by the soviet union a histogram of body wave magnitude mb values indicates a clustering of explosions at a few specific yields the most pronounced cluster consists of six explosions of yield near 500 kilotons several of these seem to be tests of warheads for major strategic systems that became operational in the late 1970s the largest soviet underground explosion is estimated to have a yield of 3500 600 kilotons somewhat smaller than the yield of the largest u s underground test a preliminary estimation of the significance of tectonic release is made by measuring the amplitude of love waves the bias in mb for novaya zemlya relative to the nevada test site is about 0 35 nearly identical to that of the eastern kazakhstan test site relative to nevada

influence of leaky boreholes on cross formational groundwater flow and contaminant transport abandoned and improperly sealed boreholes monitoring wells and water supply wells are common features at many contaminated sites these features can act as conduits that transmit contaminants between aquifers separated by otherwise continuous aquitards in this work the leaky boreholes are represented as highly conductive one dimensional line elements superimposed onto a mesh of three dimensional finite elements representing the porous medium simulation results are presented for a series of scenarios involving a simple hydrogeologic setting composed of an upper confined aquifer a middle aquitard and a lower confined aquifer the simulations examine the effect of varying the borehole properties and vertical hydraulic gradient across the aquitard and the borehole location the results show that a contaminant can rapidly migrate downward along a leaky borehole and create an extensive plume in the lower aquifer even if the borehole is filled with aquifer sediments if the borehole is an open feature across the aquitard the entire plume or a significant portion of it that is migrating into the upper aquifer can be diverted into the lower one if the vertical hydraulic gradient across the aquitard can be diverted into the lower one if the vertical hydraulic gradient across the aquitard is sufficiently strong more the peak concentration arriving at a pumping well located in the lower aquifer and the time of arrival are functions of the proximity of the leaky borehole to the pumping well and its angular offset from the central flow line passing through the surficial source overpressurization of the lower aquifer due to injection can overcome downward preexisting hydraulic gradients across the aquitard such that contaminants can rapidly migrate upward along the leaky borehole and cause contamination of the otherwise protected upper aquifer 26 refs 7 figs 1 tab less

evidence of tectonic release in long period s waves from underground nuclear explosions at the novaya zemlya test sites abstract evidence of tectonic release produced by underground nuclear explosions at novaya zemlya is present in teleseismic long period s waves sh waveforms from representative events at the southern and northern novaya zemlya test sites were modeled to determine the sh radiation patterns long period p and sv waves were also investigated to further constrain the equivalent double couple orientation of the tectonic release events within each test site have similar faulting mechanisms but there are definite differences in the tectonic release orientation between the two sites the southern test site double couple orientation is either vertical strike slip or 45 dipping thrust while the northern test site has an oblique normal dip slip orientation the limited resolution of sh signals and complexity of the observed sv waveforms along with uncertainties in the absolute explosion source strengths and t prevent unique solutions for both test sites assuming a strike slip orientation the 27 october 1973 southern novaya zemlya event has the largest tectonic release moment 1 6 10 24 dyne cm and 14 october 1969 northern event has the smallest moment 0 9 10 23 dyne cm of the 12 events studied the ratio of tectonic release moment to explosion strength varies by as much as a factor of 3 at the northern test site and by a factor of 2 at the southern site the variability of the tectonic release orientation and strength at the two test sites allows us to address the question of whether tectonic release affects yield estimation