experimental studies of electrokinetic conversions in fluid saturated borehole models experimental and theoretical studies show that there are electromagnetic em fields generated by seismic waves with two kinds of conversion mechanisms in a fluid saturated porous medium within a homogeneous formation the seismic wave generates a seismoelectric field that exists only in the area disturbed by the seismic wave and whose apparent velocity is that of the seismic wave at an interface between differing formation properties the generated seismoelectric wave is a propagating em wave that can be detected everywhere an electrode used as a receiver on the ground surface can detect the propagating em wave generated at an interface but cannot detect the seismoelectric field generated in a homogeneous formation when the electrode is in a borehole and close to a porous formation it can detect both the em waves and the seismoelectric field in this paper electrokinetic measurements are performed with borehole models made of natural rocks or artificial materials experimental results show that

impact of water saturation on seismoelectric transfer functions a laboratory study of coseismic phenomenon s u m m a r y seismic waves propagating in a porous medium under favourable conditions generate measurable electromagnetic fields due to electrokinetic effects it has been proposed following experimental and numerical studies that these so called seismoelectromagnetic couplings depend on pore fluid properties the theoretical frame describing these phenomena are based on the original biot s theory assuming that pores are fluid filled we study here the impact of a partially saturated medium on amplitudes of those seismoelectric couplings by comparing experimental data to an effective fluid model we have built a 1 m length scale experiment designed for imbibition and drainage of an homogeneous silica sand the experimental setup includes a seismic source accelerometers electric dipoles and capacitance probes in order to monitor seismic and seismoelectric fields during water saturation apparent velocities and frequency spectra in the kilohertz range are derived from seismic and electrical measurements during experiments in varying saturation conditions amplitudes of seismic and seismoelectric waves and their ratios i e transfer functions are discussed using a spectral analysis performed by continuous wavelet transform the experiments reveal that amplitude ratios of seismic to coseismic electric signals remain rather constant as a function of the water saturation in the s w 0 2 0 9 range consistently with theoretically predicted transfer functions

modification of streaming potential by precipitation of calcite in a sand water system laboratory measurements in the ph range from 4 to 12 spontaneous potentials associated with volcanic activity are often interpreted by means of the electrokinetic potential which is usually positive in the flow direction i e zeta potential of the rock is negative the water rock interactions in hydrothermal zones alter the primary minerals leading to the formation of secondary minerals this work addresses the study of calcite precipitation in a sand composed of 98 quartz and 2 calcite using streaming potential measurements the precipitation of calcite as a secondary mineral phase inferred by high calcite saturation indices and by a fall in permeability has a significant effect on the electrokinetic behaviour leading to a significant reduction in the zeta potential in absolute value and even a change in sign the measured decrease in zeta potential from 16 mv to 27 4 mv takes place as the ph rises from 4 to 7 while it remains constant at 25 1 mv as the ph increases from 8 to 10 5 for ph higher than 10 5 calcite precipitates and is expected to coat the quartz surface the measured zeta potential vary from 17 to 8 mv for ph ranging from 10 6 to 11 7 depending on the amount of precipitated calcite indicated by the decrease in permeability the observed change in sign of the electrical surface potential rules out the usual qualitative interpretation of sp anomalies in order to determine fluid circulations even at ph lower than 9 if calcite is widely present as a secondary mineral phase since the electrical surface potential of calcite depends also on co2 partial pressure and ca2 therefore sp anomalies as measured in hydrothermal field without mineralogical analyses of hydrothermal deposits and without geochemical fluid survey should be interpreted with caution

vertical seismoelectric profiling in a borehole penetrating glaciofluvial sediments 1 seismoelectric signals have been measured as a function of depth in a borehole penetrating glaciofluvial sands silts and glacial till using a broadband surface seismic source and a downhole electrode array transient electric field pulses with amplitudes of 1 to 4 v m accompanied the arrival of seismic p waves at the electrodes but no simultaneous interfacial signals were observed above the noise floor of approximately 0 2 v m the co seismic effect was strongest in a sand and gravel layer where its amplitude is consistent with the predictions of a simplified theoretical model normalization of the amplitude logs by measurements of seismic particle velocity and electrical conductivity enhanced their sensitivity to changes in lithology and porosity the results of this experiment suggest that co seismic seismoelectric effects show potential as a porosity permeability logging tool in the borehole environment

subtraction of powerline harmonics from geophysical records harmonic noise generated by power lines and electric railways has plagued geophysicists for decades the noise occurs as electric and magnetic fields at the fundamental frequency of power transmission typically 60 hz in north america and its harmonics it may be recorded directly during time domain measurements of electric and magnetic felds or indirectly by geophone cables during the acquisition of seismic data

seismoelectric imaging of the vadose zone of a sand aquifer we have acquired a 300 m seismoelectric section over an unconfined aquifer to demonstrate the effectiveness of interfacial signals at imaging interfaces in shallow sedimentary environments the seismoelectric data were acquired by using a 40 kg accelerated weight drop source and a 24 channel seismoelectric recording system composed of grounded dipoles preamplifiers and seismographs in the shot records interfacial signals were remarkably clear they arrived simultaneously at offsets as far as 40 m from the seismic source the most prominent signal was generated at the water table at a depth of approximately 14 m and had peak amplitudes on the order of 1 v m a weaker response was generated at a shallower interface that is interpreted to be a water retentive layer the validity of these two laterally continuous events and of other discontinuous events indicative of vadose zone heterogeneity is corroborated by the presence of reflections exhibiting similar characteristics in a ground penetrating rada

bayesian inversion of joint sh seismic and seismoelectric data to infer glacier system properties abstract in glacial studies properties such as glacier thickness and the basement permeability and porosity are key to understand the hydrological and mechanical behaviour of the system the seismoelectric method could potentially be used to determine key properties of glacial environments here we analytically model the generation of seismic and seismoelectric signals by means of a shear horizontal seismic wave source on top of a glacier overlying a porous basement considering a one dimensional setting we compute the seismic waves and the electrokinetically induced electric field we then analyse the sensitivity of the seismic and electromagnetic data to relevant model parameters namely depth of the glacier bottom porosity permeability shear modulus and saturating water salinity of the glacier basement moreover we study the possibility of inferring these key parameters from a set of very low noise synthetic data adopting a bayesian framework to pay particular attention to the uncertainty of the model parameters mentioned above we tackle the resolution of the probabilistic inverse problem with two strategies 1 we compute the marginal posterior distributions of each model parameter solving multidimensional integrals numerically and 2 we use a markov chain monte carlo algorithm to retrieve a collection of model parameters that follows the posterior probability density function of the model parameters given the synthetic data set both methodologies are able to obtain the marginal distributions of the parameters and estimate their mean and standard deviation the markov chain monte carlo algorithm performs better in terms of numerical stability and number of iterations needed to characterize the distributions the inversion of seismic data alone is not able to constrain the values of porosity and permeability further than the prior distribution in turn the inversion of the electric data alone and the joint inversion of seismic and electric data are useful to constrain these parameters as well as other glacial system properties furthermore the joint inversion reduces the uncertainty of the model parameters estimates and provides more accurate results

detection of fluid flow variations at the nankai trough by electric and magnetic measurements in boreholes or at the seafloor detection of changes in the flow rate of expelled fluids in accretionary prisms by monitoring of electric and magnetic fields is discussed a numerical model of the electric and magnetic fields associated with fluid flow variations at the nankai trough is presented which gives a numerical solution of the coupled system of electric convection currents and conduction currents that directly determines the magnetic anomaly itself measurements in a borehole located between two vents are shown to be well adapted to detection of fluid flow variations using the vertical gradient of the electric potential and the horizontal magnetic field the vertical electric field is about 10 mv km up to 500 m depth where there is a lithologic reflector and about 50 mv km below this reflector the horizontal gradient of the magnetic field is 2 nt km at the seafloor modelization with a lower fault conductivity and a larger decollement thickness has also been modeled the vertical gradient of the horizontal magnetic field is 5 to 15 nt km a variation of 3 mv and 1 5 to 3 nt at 600 m depth in a borehole could reveal a fluid flow rate variation of 20 which is a reasonable fluid flow change based on some observations at short scale time since a 1 5 to 3 nt anomaly seems easier to detect than a 3 mv anomaly it is likely that the variation of the magnetic field would more sensitively reveal fluid flow variations when monitoring the magnetic field at the seafloor a change of 0 4 nt km in the horizontal gradient could reveal a fluid flow rate variation of 20

electromagnetic to seismic conversion a new direct hydrocarbon indicator we present novel methods that directly detect hydrocarbons based on conversions between electromagnetic and seismic energy we first introduce the subject and then discuss the experimental methods in three field tests next we present the results of the tests and then end with a few model results and thoughts about future applications

curvelet based seismoelectric data processing seismoelectromagnetic conversions are induced through electrokinetic phenomena occurring when passing seismic waves induce relative fluid to solid displacements information on porous material properties provided by the type i coseismic electric field accompanying surface and body waves is limited to the vicinity of the electrical receivers as opposed to the type ii electromagnetic interface response ir which can help detect porous contrasts and or fluid changes within the subsurface at depth for general field geometries the problem is that type ii disturbances exhibit lower amplitudes than type i fields and are difficult to access directly hence separating both types of waves is a critical step when processing seismoelectric data synthetic seismograms and electrograms generated with a full waveform seismoelectric forward modelling code written by garambois dietrich enabled us to study the behaviour of the ir s characteristic dipolar amplitude pattern recovered through filtering the definitive version is available at www blackwell synergy com to better preserve the ir amplitudes we have developed a new filtering strategy based on the fast discrete curvelet transform seismic or seismoelectric wave fronts can be optimall described using this multiscale decomposition over multidirectional anisotropic needle shape structures we have built a mask in the curvelet domain zeroing out seismoelectric samples corresponding to non zero samples from the accelerogram thus taking advantage of the relationship between seismic and seismoelectric waves for type i fields this mask consists of a threshold function combined with a gaussian distribution promoting horizontal i e zero slowness directions when applied to synthetic data this filter enabled to successfully extract the ir although less altering its dipolar radiation pattern than the conventional dip based techniques this strategy was successfully applied to a seismoelectric data set acquired in sedimentary deposits and permitted to isolate an ir generated at the water table

ζ potential measurement of volcanic rocks from aso caldera 1 we deduced the z potential of various rocks in aso caldera from streaming potential measurements in laboratory in contrast to the conventional observation that the z potential of crustal rocks is mostly negative under typical geologic conditions almost half of the samples equilibrated with dilute kcl solution show positive values of z potential at ph 4 5 5 5 the samples showing positive z are characterized by relatively low sio2 content and abundance of elements having high isoelectric points and found to be localized around the summit of mt takadake where the positive correlation between self potential sp and altitude is observed we emphasize that measurements of z potential of volcanic rocks are very important to give more appropriate interpretations of sp data from volcanic fields index terms 0634 electromagnetics measurement and standards 0925 exploration geophysics magnetic and electrical methods 5199 physical properties of rocks general or miscellaneous 8499 volcanology general or miscellaneous 1832 hydrology groundwater transport citation hase h t ishido s takakura t hashimoto k sato and y tanaka z potential measurement of volcanic rocks from aso caldera geophys res lett 30 23 2210 doi 10 1029 2003gl018694 2003

an analytical solution to assess the sh seismoelectric response of the vadose zone fil monachesi leonardo bruno universidad nacional de rio negro sede alto valle instituto de investigaciones en paleobiologia y geologia argentina consejo nacional de investigaciones cientificas y tecnicas argentina

depth determinations of shallow hydrothermal systems by self potential and multi scale wavelet tomography in hydrothermal studies the depth of the hydrothermal system is always required but rarely known via traditional geophysical exploration techniques while previous studies have shown that continuous wavelet transform algorithms applied to self potential data can theoretically determine the depth of the hydrothermal fluids this study uses multi scale wavelet tomography with multiple wavelets field measurements and geophysical models to accurately determine this depth on stromboli waita and masaya volcanoes multi scale wavelet tomography of field measurements gives reproducible depth results supported by independent geophysical measurements and models and accurately locates the main water flow paths at shallow depths unlike other traditional geophysical methods multi scale wavelet tomography using self potential data is a low cost tool to rapidly determine depths of the shallowest hydrothermal structures this approach has the potential to significantly enhance our ability to locate geothermal systems and monitor active volcanoes

seismoelectric and electroseismic responses to a point source in a marine stratified model abstract we investigate the seismoelectric electroseismic wavefields excited by a point source in an air seawater three layered porous medium configuration containing a hydrocarbon layer the results show that if an explosive source for excitation is used receivers at seafloor can record the coseismic electromagnetic fields accompanying the p s fluid acoustic waves and the interface responses converted from the acoustic waves at seafloor interface and from the seismic waves at the interfaces beneath the seafloor employing a vertical electric dipole source shows that with the exception of the interface responses converted from electromagnetic waves at seafloor the interface responses converted from transmitted electromagnetic waves at the interfaces beneath the seafloor can also be identified given that the strength of the explosive source is within excitation capability of industry air guns the generated interface responses from the hydrocarbon layer can be detected by current electromagnetic sensors considering the low ambient noise at the seafloor our results demonstrate the feasibility of the seismoelectric method applied to marine hydrocarbon exploration electroseismic modelling results suggest that it is not practical to employ this method to prospect marine hydrocarbon layer due to the weak interface response signal unless a much larger current is injected into seafloor

borehole electrokinetic responses in fracture dominated hydraulically conductive zones electrokinetic borehole logging experiments conducted in fracture dominated devonian metasediments and carboniferous limestone boreholes containing dissolu tion discontinuities indicate a strong relative amplitude correlation between a downhole electrokinetic response and previously obtained hydrogeological data for the respective boreholes voltages in the range 0 2 1 5 volt were recorded per mpa of gauge pressure induced in the borehole fluid a relationship between fracture aperture and the frequency content of the electrical data has also been observed

measurement of streaming potential coupling coefficient in sandstones saturated with high salinity nacl brine 1 we present measurements of the streaming potential coupling coefficient in intact sandstone samples saturated with nacl brines at concentrations up to 5 5 moll 1 the values we record at low salinity are consistent with those reported previously as brine salinity increases the coupling coefficient decreases in magnitude but is still measureable up to the saturated concentration limit the magnitude of the zeta potential also decreases with increasing salinity but approaches a constant value at high salinity this behaviour is not captured by current models of the electrical double layer our results suggest that streaming potential measurements may be used to monitor flow in saline subsurface environments such as deep saline aquifers and hydrocarbon reservoirs however they were obtained at laboratory temperature future work will focus on the effect of elevated temperatures at high salinity

zeta potential measured for an intact granite sample at temperatures to 200 c 1 streaming potential was measured in an intact granite sample saturated with aqueous kcl solutions at three different concentrations at temperatures between 25 and 200 c the magnitudes of the streaming potential coefficient and of the surface conductance which dominates the sample conductivity both increase with increasing temperature using a capillary model we found that the magnitude of the zeta potential also increases with increasing temperature

dependence of seismoelectric amplitudes on water content summary the expectation behind seismoelectric field measurements is to achieve a combination of the sensitivity of electrical properties to water content and permeability and the high spatial resolution of seismic surveys a better understanding of the physical processes and a reliable quantification of the conversion between seismic energy and electric energy are necessary and need to take into account the effect of water content especially for shallow subsurface investigations we performed a field survey to quantify the seismoelectric signals as the water content changed we measured seismoelectric signals induced by seismic wave propagation by repeating the observations on the same two profiles during several months the electrical resistivity was monitored to take into account the water content variations weshowthatthehorizontalcomponentoftheseismoelectricfield normalizedwithrespectto the horizontal component of the seismic acceleration is inversely proportional to the electrical resistivity 0 42 0 25 assuming that the observed resistivity changes depend only on the water content this result implies that the electrokinetic coefficient should increase with increasing water saturation taking into account the water saturation and combining our results with the archie law for the resistivity in non saturated conditions the normalized seismoelectric field is a power law of the effective saturation with the exponent 0 42 0 25 n where n is archie s saturation exponent

anatomy of a seismoelectric conversion measurements and conceptual modeling in boreholes penetrating a sandy aquifer 1 conversions of compressional seismic waves to electric fields have been measured in two boreholes drilled in an unconfined sandy aquifer on the gnangara mound near perth australia the seismoelectric conversions at both field sites occurred in the vicinity of the water table at 13 m depth and yielded maximum amplitudes of 1 v m using a sledgehammer source on surface partially cemented layers inferred from geological and geophysical logs straddle the water table and may play a role in generating the conversion and influencing its amplitude distribution the dense vertical sampling used in these borehole experiments reveals spatial and temporal polarity reversals of the interfacial signal which provide new evidence in support of the conceptual model for seismoelectric conversions at interfaces we demonstrate that the growth rate of the source zone and its maximum vertical extent below the water table are encoded in the polarity of the interfacial signal these experiments confirm that vertical seismoelectric profiling can be used to gain further insight into seismoelectric conversions and characteristics of interfaces that makes them amenable to detection

a geochemical and geophysical investigation of the hydrothermal complex of masaya volcano nicaragua abstract masaya volcano nicaragua is a persistently active volcano characterized by continuous passive degassing for more than 150 years through the open vent of santiago crater this study applies self potential soil co 2 and ground temperature measurements to highlight the existence of uprising fluids associated to diffuse degassing structures throughout the volcano the diffuse degassing areas are organized in a semi circular pattern and coincide with several visible and inferred surface volcanic structures cones fissure vents and likely consist of a network of buried faults and dykes that respectively channel uprising flow and act as barrier to gravitational groundwater flow water depths have been estimated by multi scale wavelet tomography of the self potential data using wavelets from the poisson kernel family compared to previous water flow models our water depth estimates are shallower and mimic the topography typically less than 150 m below the surface between 2006 and 2010 the depths of rising fluids along the survey profiles remained stable suggesting that hydrothermal activity is in a steady state this stable activity correlates well with the consistency of the volcanic activity expressed at the surface by the continuously passive degassing when compared to previous structural models of the caldera floor it appears that the diffuse degassing structures have an important effect on the path that shallow groundwater follows to reach the laguna de masaya in the eastern part of the caldera the hydrogeological system is therefore more complex than previously published models and our new structural model implies that the flow of shallow groundwater must bypass the intrusions to reach the laguna de masaya furthermore these diffuse degassing structures show clear evidence of activity and must be connected to a shallow magmatic or hydrothermal reservoir beneath the caldera as such the heat budget for masaya must be significantly larger than previously estimated

evidence of the theoretically predicted seismo magnetic conversion summary seismo electromagnetic phenomena in porous media arise from seismic wave induced fluid motion in the pore space which perturbs the equilibrium of the electric double layer this paper describes with details the original experimental apparatus built within the ultra shielded chamber of the low noise underground laboratory of rustrel france we measured seismo magnetic conversions in moist sand using two induction magnetometers and a pneumatic seismic source to generate the seismic wave propagation we ensured to avoid the magnetometer vibrations which could induce strong disturbances from induction origin interpretation of the data is improved by an analytical description of phase velocities for fast pf and slow ps longitudinal modes transverse mode s as well as the extensional mode due to the cylindrical geometry of the sample the purpose of this paper is to provide elements to measure correctly coseismic seismomagnetic fields and to specify their amplitude the seismic arrivals recorded in the sample showing a 1200 1300 m s 1 velocity have been associated to p and extensional waves the measured seismo magnetic arrivals show a velocity of about 800 m s 1 close to the calculated phase velocity of s waves therefore we show that the seismo magnetic field is associated to the transverse part of the propagation as theoretically predicted by pride 1994 but never measured up to now moreover the combined experimental and analytical approaches lead us to the conclusion that the measured seismo magnetic field is probably about 0 035 nt for a 1 m s 2 seismic source acceleration 0 1 g

radon transform wave field separation for vertical seismic profiling data the data obtained by the vertical seismic profiling vsp method require unique processing before interpretation an important step is the separation of upgoing and downgoing signals by application of an f k velocity filter and muting of the direct wave similarly if the vsp section is transformed to the p plane the upgoing and downgoing wave fields become separable because they map to different p quadrants according to their dips this allows either wave field to be reconstructed by application of the inverse radon transform after windowing in the p plane results obtained by the radon transform wave field separation rtws method are similar to those obtained by f k velocity filtering however by implementing an amplitude ratio testing filter in the forward slant stack the quality of the reconstructed wave field is much improved for a specific range of p stack values in the forward transform this filter sorts and removes the unwanted events from the desired ones by testing their consistency

seismoelectric wave propagation numerical modelling in partially saturated materials to better understand and interpret seismoelectric measurements acquired over vadose environments both the existing theory and the wave propagation modelling programmes available for saturated materials should be extended to partial saturation conditions we propose here an extension of pride s equations aiming to take into account partially saturated materials in the case of a water air mixture this new set of equations was incorporated into an existing seismoelectric wave propagation modelling code originally designed for stratified saturated media this extension concerns both the mechanical part using a generalization of the biot gassmann theory and the electromagnetic part for which dielectric permittivity and electrical conductivity were expressed against water saturation the dynamic seismoelectric coupling was written as a function of the streaming potential coefficient which depends on saturation using four different relations derived from recent laboratory or theoretical studies in a second part this extended programme was used to synthesize the seismoelectric response for a layered medium consisting of a partially saturated sand overburden on top of a saturated sandstone half space subsequent analysis of the modelled amplitudes suggests that the typically very weak interface response ir may be best recovered when the shallow layer exhibits low saturation we also use our programme to compute the seismoelectric response of a capillary fringe between a vadose sand overburden and a saturated sand half space our first modelling results suggest that the study of the seismoelectric ir may help to detect a sharp saturation contrast better than a smooth saturation transition in our example a saturation contrast of 50 per cent between a fully saturated sand half space and a partially saturated shallow sand layer yields a stronger ir than a stepwise decrease in saturation

seismic demigration migration in the curvelet domain curvelets can represent local plane waves they efficiently decompose seismic images and possibly imaging operators we study how curvelets are distorted after demigration followed by migration in a different velocity model we show that for small local velocity perturbations the demigration migration is reduced to a simple morphing of the initial curvelet the derivation of the expected curvature of the curvelets shows that it is easier to sparsify the demigration migration operator than the migration operator an application on a 2d synthetic data set generated in a smooth heterogeneous velocity model and with a complex reflectivity demonstrates the usefulness of curvelets to predict what a migrated image would become in a locally different velocity model without the need for remigrating the full input data set curvelets are thus well suited to study the sensitivity of a prestack depth migrated image with respect to the heterogeneous velocity model used for migration

geophysical applications of electrokinetic conversion in volume 1 of geophysics 1936 r r thompson of humble oil and refining company proposed that the coupling of seismic and electrical energy can be used as an exploration tool subsequent efforts were directed toward using electric field antennas as geophones small scale studies concluded that antennas are not as sensitive as conventional geophones and their response is highly variable depending on the local soil conditions by 1959 martner and sparks of pan american petroleum reported in geophysics a systematic study of seismoelectric coupling using explosives at various depths their results were the first to show that the conversion of seismic to electromagnetic energy at the water table could be detected using surface antennas no studies have systematically explored the full potential of electroseismic methods using the same level of experimental sophistication used in seismic exploration

using borehole electroseismic measurements to detect and characterize fractured permeable zones in 1996 we measured stoneley wave induced electrical fields in an uncased water well drilled in fractured granite and diorite near hamilton massachusetts stoneley waves generated by sledgehammer blows to the surface casing produced a flow of pore fluid in permeable zones intersected by the borehole in turn this flow induced a streaming electrical field even though these electrical signals were very small tens of microvolts we were able to detect them using electrodes placed in the borehole after power line and telluric signals were canceled by remote referencing and notch filtering amplitude analysis of the electrical fields confirmed that they were induced by fluid flow in the fractured formation the normalized amplitudes of these electrical fields correlate with the fracture density log and agree with the theoretical model for this electroseismic phenomenon our biot theory based model predicts that borehole electroseismic measurements can be used to characterize permeable zones according t

permeability inversion from low frequency seismoelectric logs in fluid saturated porous formations in this paper a method is proposed to invert permeability from seismoelectric logs in fluid saturated porous formations from the analysis of both the amplitude and the phase of simulated seismoelectric logs we find that the stoneley wave amplitude of the ratio of the converted electric field to the pressure rep is sensitive to porosity rather than permeability while the tangent of the rep s phase is sensitive to permeability the rep s phase reflects the phase discrepancy between the electric field and the pressure at the same location in the borehole we theoretically derive the frequency dependent expression of the rep of the low frequency stoneley wave and find that the tangent of the rep s argument is approximately in inverse proportion to permeability we obtain an inversion formula and present the permeability inversion method by using the tangent of the rep s phase to test this method the permeabilities of different sandstones are inverted from the synthetic full waveform data of seismoelectric logs a modified inversion process is proposed based on the analysis of inversion errors by which the relative errors are controlled below 25 and they are smaller than those of the permeability inversion from the stoneley wave of acoustic logs

new heat flow data from the immediate vicinity of the kola super deep borehole vertical variation in heat flow confirmed and attributed to advection abstract we present new heat flow values and other geothermal data in the upper crystalline crust in the immediate vicinity of the 12 4 km deep kola super deep borehole nw russia our results show a systematic vertical increase in geothermal gradient and heat flow density as deep as we could measure 1 6 km our results confirm earlier results on vertical heat flow trends of in the uppermost part of the kola super deep hole and imply that the thermal regime is not in steady state conductive conditions in an area of 3 km 5 km measurements were performed in 1 2 km deep boreholes surrounding the kola super deep hole and on core samples from these holes temperature logs are available from 36 holes core data exists from 23 boreholes with a total length of 11 5 km at a vertical resolution of 10 m we carried out a very detailed study on thermal conductivity with regard to anisotropy inhomogeneity and temperature dependence tensor components of thermal conductivity were determined on 1375 core samples from 21 boreholes in 3400 measurements additionally we measured specific heat capacity heat generation rate density porosity and permeability on selected subsets of core samples heat flow from 19 boreholes varies between 31 and 45 mw m 2 with an average value of 38 mw m 2 in most boreholes the vertical heat flow profiles show a considerable variation with depth this is consistent with observations in the upper part of the kola super deep borehole we conclude that this variation is not caused by technical operations but reflects a natural process it is considered to be due to a combination of advective structural and paleoclimatic effects preliminary 3 d numerical modeling of heat and flow in the study area provides an indication of relative contributions of each of these factors advective heat transfer turns out to have a major influence on the vertical variation of heat flow although transient changes in surface temperature may also cause a significant variation heterogeneity of the rocks in the study area is less important

influence of water pressure dynamics and fluid flow on the streaming potential response for unsaturated conditions streaming potentials are produced by electrokinetic effects in relation to fluid flow and are used for geophysical prospecting the aim of this study is to model streaming potential measurements for unsaturated conditions using an empirical approach a conceptual model is applied to streaming potential measurements obtained from two drainage experiments in sand the streaming potential data presented here show a non monotonous behaviour with increasing water saturation following a pattern that cannot be predicted by existing models a model involving quasi static and dynamic components is proposed to reproduce the streaming potential measurements the dynamic component is based on the first time derivative of the driving pore pressure the influence of this component is investigated with respect to fluid velocity which is very different between the two experiments the results demonstrate that the dynamic component is predominant at the onset of drainage in experiments with the slowest water flow on the other hand its influence appears to vanish with increasing drainage velocity our results suggest that fluid flow and water distribution at the pore scale have an important influence on the streaming potential response for unsaturated conditions we propose to explain this specific streaming potential response in terms of the behaviour of both rock water interface and water air interfaces created during desaturation processes the water air interfaces are negatively charged as also observed in the case of water rock interfaces both the surface area and the flow velocity across these interfaces are thought to contribute to the non monotonous behaviour of the streaming potential coefficient as well as the variations in its amplitude the non monotonous behaviour of air water interfaces created during the flow was highlighted as it was measured and modelled by studies published in the literature the streaming potential coefficient can increase to about 10 to 40 when water saturation decreases such an increase is possible if the amount of water air interfaces is increased in sufficient amount which can be the case

the positive north atlantic oscillation with downstream blocking and middle east snowstorms impacts of the north atlantic jet abstracta recent study revealed that cold winter outbreaks over the middle east and southeastern europe are caused mainly by the northeast southwest ne sw tilting of european blocking eb associated with the positive phase north atlantic oscillation nao here the north atlantic conditions are examined that determine the eb tilting direction defined as being perpendicular to the dipole anomaly orientation using daily reanalysis data the nao events are classified into strong sjn and weak wjn north atlantic jet types a composite analysis shows that the eb is generally stronger and located more westward and southward during sjn events than during wjn events during sjn events the nao and eb dipoles exhibit ne sw tilting which leads to strong cold advection and large negative temperature anomalies over the middle east and southeastern europe in contrast northwest southeast nw se tilting without strong negative temperature anomalies over the middle east is seen during wjn events a nonline