dual porosity mechanism for transient groundwater and gas anomalies induced by external forcing abstract the geochemical response of groundwater to external forcing is studied in a tunnel hosted in fractured gneiss near and above an artificial lake having large water level variations dripping waters have been monitored in two zones characterized by highly different flow rates representing different contributions of water from matrix porosity and fractures transient increases of sulfate and magnesium concentrations observed in both zones are not related to meteorology but associated with radon bursts into the tunnel air this indicates that transient enhancement of conductance with discharges of saline water and radon from the matrix porosity to the fractures is a mechanism able to produce both groundwater and gas anomalies in response to hydrogeological or mechanical processes such as increases in pore pressure or changes in crack geometry besides its applications to environmental issues the proposed discharge mechanism may be relevant for the understanding of geochemical precursors of earthquakes as an alternative to aquifer mixing

a case for a downwasting mountain glacier during termination i vercenik valley northeastern turkey field evidence of palaeoglacial records in the vercenik valley in the eastern black sea mountains was examined and 19 samples for surface exposure dating with cosmogenic 10 be were collected with the aim of increasing knowledge on the amplitude and frequency of palaeoglacier advances in anatolia glacial erosional features were mapped and the flow directions of the palaeoglaciers were determined the vercenik palaeoglacier advanced before 26 1 k 1 2 k yr the last glacial maximum lgm advance continued until 18 8 k 1 0 k yr the vercenik palaeo glacier collapsed during termination i after 17 7 k 0 8 k yr there was no more ice in the main valley the vercenik palaeoglacier most probably then separated into five small glaciers that were restricted to the tributary valleys among these the hemsin palaeoglacier completed its recession around 15 7 k 0 8 k yr on the basis of glacial erosion features a lateglacial glacier advance can be identified evidence of the little ice age advance appears to be absent the results from this valley system seem to be consistent with the first results from the adjacent kavron valley and with the anatolian lgm palaeoclimate the sea surface temperature minima in the western mediterranean the deposition of red clay layers in the black sea and deposition of the heinrich 1 layer in the north atlantic copyright 2007 john wiley sons ltd

paleoglacial records from kavron valley ne turkey field and cosmogenic exposure dating evidence abstract kavron valley lies in the kackar mountain range of northeastern anatolia and is a north south oriented typically u shaped glacial valley consisting of a main and three tributary valleys the quaternary units that outcrop in this valley have been mapped and 22 samples have been processed for surface exposure dating using cosmogenic 10 be according to the 10 be ages the advance of the kavron paleoglacier began at least 26 0 1 2 kyr ago with the last glacial maximum lgm advance continuing until 18 3 0 9 kyr after this time the kavron paleoglacier receded although the magnitude of this recession is still unknown subsequent to this retreat the glacier most probably separated into three smaller glaciers that were restricted to the tributary valleys ifrit derebasi and mezovit paleoglaciers the main valley was definitely ice free by 15 5 0 7 kyr ago with the mezovit paleoglacier completing its recession around 15 5 0 6 kyr a late glacial advance took place around 13 0 0 8 to 11 5 0 8 kyr and little ice age moraines appear to be absent our results from the kavron valley system seem to be consistent with the lgm paleoclimate record of anatolia which has been delineated by data gathered from lowlands and lakes the deposition of red clay layers in the northwestern black sea and the deposition of heinrich 1 layers in the north atlantic

radon cl and so42 anomalies in hot spring water associated with the 1995 earthquake swarm off the east coast of the izu peninsula central japan abstract radon concentrations were continuously monitored in hot spring water in a 200 m deep well in the yugano hot spring area izu peninsula japan from july to december 1995 concentrations of cl and so 4 2 were measured in the hot spring water about once a month from may to december 1995 the rn concentrations in the hot spring water increased significantly in september and october 1995 when the 1995 earthquake swarm off the e coast of the izu peninsula occurred at a distance of about 30 km from the observation well the 1995 earthquake swarm began on 11 september and became most active from the end of september to the beginning of october the rn concentration rose gradually from 8 september 3 days before the onset of the swarm activity increasing by about 50 by 17 september it remained high in october but had returned to normal by the end of november however cl and so 4 2 concentrations doubled suddenly from 22 to 23 september and remained high until the end of november a good correlation between cl and so 4 2 concentrations suggests the same mechanism for their anomalous increases probably mixing of water with high cl and so 4 2 concentrations caused by crustal deformation related to the seismic swarm activity however the anomalous increase in rn concentration which began 15 days before these anion increases cannot be explained by the same water mixing mechanism a possible mechanism for the anomalous rn increase is the formation of microcracks caused by compressional stress which preceded the onset of the earthquake swarm

stereological analysis of fractures in the roselend tunnel and permeability determination 1 fracture traces and water fluxes have been determined along the 128 m long roselend tunnel french alps fractures can be classified into two families large fractures which intersect the tunnel and small fractures which partially intersect it three different zones in the tunnel are distinguished with mild low and high water fluxes starting from the entrance a stereological analysis of the trace length probability densities of small fractures provides the fracture diameter probability density distribution which is best approximated by a power law large fractures are assumed monodisperse with a 5 m estimated radius the generated fracture networks obtained by combining large and small fractures do percolate while networks consisting of only small fractures do not percolate computed macroscopic permeabilities of the fracture networks are in agreement with the observed water fluxes when the fracture permeability is a power law of its lateral extent with an exponent equal to 3

geochemical precursors to seismic activity studies of earthquake precursory phenomena during the last several decades have found that significant geophysical and geochemical changes can occur prior to intermediate and large earthquakes among the more intensely investigated geochemical phenomena have been 1 changes in the concentrations of dissolved ions and gases in groundwaters and 2 variations in the concentrations of crustal and mantle volatiles in ground gases the concentration changes have typically showed no conanomalies trend either increasing or decreasing and the spatial and temporal distribution of the observed anomalies have been highly variable as a result there is little agreement on the physical or chemical processes responsible for the observed anomalies mechanisms proposed to account for precursory groundwater anomalies include ultrasonic vibration pressure sensitive solubility pore volume collapse fracture induced increases in reactive surfaces and aquifer breaching fluid mixing precursory changes in soil gas composition have been suggested to result from pore volume collapse micro fracture induced exposure of fresh reactive silicate surfaces and breaching of buried gas rich horizons an analysis of the available field and laboratory data suggests that the aquifer breaching fluid mixing ab fm model can best account for many of the reported changes in temperature dissolved ion and dissolved gas concentrations in groundwater ultrasonic vibration and pressure sensitive solubility models cannot reasonably account for the geochemical variations observed and although the pore collapse model could explain some of the observed chemical changes in groundwater and ground gas uncertainties remain regarding its ability to generate anomalies of the magnitude observed other geochemical anomalies in particular those associated with hydrogen and radon seem best accounted for by increases in reactive surface areas irsa model that may accompany precursory deformation around the epicenter of an impending earthquake analysis of the probable response of these models to the earthquake preparation process as well as to other environmental factors suggests that geochemical monitoring programs can provide information that may be valuable in forecasting the probability of an earthquake however because of the complexity of the earthquake preparation process the absolute prediction of seismic events using geochemical methods alone does not presently appear to be feasible

spatiotemporal variability of the precipitation dipole transition zone in the western united states 1 el nino southern oscillation related hydroclimatic variability in the western united states is characterized by a north south dipole pattern of precipitation anomalies with opposing signs here i use a high resolution dataset to analyze spatiotemporal patterns in the transition zone between the centers of opposite association results indicate that the transition zone is spatially limited west of the continental divide consisting of a narrow zone within the 40 42 n latitude band and portions of eastern washington eastern oregon and western colorado the transition zone was narrower when the southern oscillation index and the pacific decadal oscillation pdo were in a constructive phase and during the negative atlantic multidecadal oscillation phase although the transition zone has remained remarkably stationary across the great basin shifts likely pdo related have occurred over time in the west coast states implications for water resource planning in river basins underlying the transition zone vary by region

earthquake related elemental and isotopic lead anomaly in a springwater abstract elemental and isotopic analyses of lead present at ultra trace levels were obtained with a double focusing inductively coupled plasma mass spectrometer on a pyrenean springwater the sampling was carried out across a time series of 598 days encompassing an earthquake of magnitude 5 2 lead concentrations show a tenfold increase and isotopic compositions shift toward anthropogenic values four days prior to the quake the time lag between these geochemical anomalies and the earthquake combined with hydrogeological constraints are then used to infer where and when strain changes during earthquake preparation processes went beyond the threshold required to temporarily mix waters from normally independent aquifers the occurrence of pre seismic centrifugal strain waves propagating from the epicenter area is proposed on the basis of the observed geochemical anomalies

cosmogenic exposure dating of snow avalanche ridges eastern black sea mountains ne turkey abstract the kavron and vercenik valleys are located in the eastern black sea mountain range in northeastern turkey this study identified several snow avalanche ridges in these glacial valleys those in the kavron valley were mapped in detail and the largest and geomorphologically oldest ridge of each valley was sampled for cosmogenic exposure dating with 10 be three granitic boulders from kavron valley and two granitic boulders from vercenik valley were processed the avalanche ridges had been mapped as terminal moraines of pleistocene glaciations by previous researchers the 10 be exposure dates obtained from each boulder are different ranging from 7 4 to 2 3 kyr bp and indicate that each represents an individual snow avalanche event these ages show that the events occurred during the holocene and the 10 be results confirm that the snow avalanche ridge build up started in the late glacial after the retreat of paleoglaciers in the vercenik and kavron valleys

helium degassing related to the kobe earthquake the sup 3 he sup 4 he ratios of groundwaters at nishinomiya city close to the epicenter decreased immediately after the 1995 kobe earthquake in japan while the sup 4 he sup 20 ne ratios increased the delta d and delta sup 18 o values of the groundwaters were identical before and after the earthquake apparent groundwater ages calculated by tritium sup 3 he concentrations also did not change if we correct the addition of radiogenic helium into the samples by the earthquake these observations may be attributed to following phenomenon 1 release of radiogenic he as a result of micro fracturing of rocks during the earthquake followed by degassing from the aquifer system in the amount of about 4 0 1 3 x 10 sup 9 cm sup 3 stp cm sup 3 rock 2 simple mixing of low tritium water with high radiogenic helium in the clay layer and high tritium water with atmospheric helium in the aquifer and 3 flow path mixing in the region of the sample screen if we take the 1 degassing hypothesis as a function of micro fracturing it is possible to calculate the total he degassing related to the kobe earthquake 4 x 10 sup 11 cm sup 3 stp which is about 3 of the steady state global he flux of 1 2 x 10 sup 13 cm supmore 3 stp year thus earthquake may play an important role in he degassing from the solid earth less

detectability and significance of 12 hr barometric tide in radon 222 signal dripwater flow rate air temperature and carbon dioxide concentration in an underground tunnel summary searching for small periodic signals such as the 12 hr s2 barometric tide and monitoring their amplitude as a function of time can provide important clues on the complex processes affecting fluid transport in unsaturated fractured media under multiple influences here first we show that a modified spectrogram analysis msa is more efficient than simple fourier transform to reveal weak periodic signals secondly we show how transient periodic signals can be monitored as a function of time using spectrograms these methods are applied to time series of radon and carbon dioxide concentration dripwater flow rates and air temperature measured during several years in the roselend dead end tunnel located in the french alps near an artificial lake a weak s2 line is evidenced in radon concentration with enhanced amplitude during transient radon bursts similarly the s2 line is observed using msa in dripwater flow rates which sample mainly fracture flow as suggested by a hydrochemical analysis while it is not seen in dripwater flow rates sampling matrix flow in the absence of a strong 24 hr line the presence of a s2 line suggests sensitivity to barometric pressure and thus a significant advective contribution in radon and some dripwater transport no s2 line is observed in the carbon dioxide time series the temporal structure of the s2 component however is not similar in the radon concentration and the dripwater flow rates suggesting in particular that dripwater does not play a significant role in the generation of radon bursts temperature time series exhibit a significant s2 contribution induced by atmospheric pressure spatially organised in the tunnel decreasing vertically upwards a remarkable transient temperature inversion during radon bursts suggests that the additional advective air contributions responsible for the radon bursts occur from the non saturated rocks below the tunnel

evolution of the conceptual model of unsaturated zone hydrology at yucca mountain nevada abstract yucca mountain is an arid site proposed for consideration as the united states first underground high level radioactive waste repository low rainfall approximately 170 mm yr and a thick unsaturated zone 500 1000 m are important physical attributes of the site because the quantity of water likely to reach the waste and the paths and rates of movement of the water to the saturated zone under future climates would be major factors in controlling the concentrations and times of arrival of radionuclides at the surrounding accessible environment the framework for understanding the hydrologic processes that occur at this site and that control how quickly water will penetrate through the unsaturated zone to the water table has evolved during the past 15 yr early conceptual models assumed that very small volumes of water infiltrated into the bedrock 0 5 4 5 mm yr or 2 3 percent of rainfall that much of the infiltrated water flowed laterally within the upper nonwelded units because of capillary barrier effects and that the remaining water flowed down faults with a small amount flowing through the matrix of the lower welded fractured rocks it was believed that the matrix had to be saturated for fractures to flow however accumulating evidence indicated that infiltration rates were higher than initially estimated such as infiltration modeling based on neutron borehole data bomb pulse isotopes deep in the mountain perched water analyses and thermal analyses mechanisms supporting lateral diversion did not apply at these higher fluxes and the flux calculated in the lower welded unit exceeded the conductivity of the matrix implying vertical flow of water in the high permeability fractures of the potential repository host rock and disequilibrium between matrix and fracture water potentials the development of numerical modeling methods and parameter values evolved concurrently with the conceptual model in order to account for the observed field data particularly fracture flow deep in the unsaturated zone this paper presents the history of the evolution of conceptual models of hydrology and numerical models of unsaturated zone flow at yucca mountain nevada flint a l flint l e kwicklis e m bodvarsson g s fabryka martin j m 2001 hydrology of yucca mountain reviews of geophysics in press this retrospective is the basis for recommendations for optimizing the efficiency with which a viable and robust conceptual model can be developed for a complex site

springwater chloride ion anomaly prior to a ml 5 2 pyrenean earthquake abstract we performed over a 598 day sampling period chemical analyses of commercially bottled spring water namely alet water rising in the vicinity of saint paul de fenouillet french eastern pyrenees where a ml 5 2 earthquake occurred these data display a chloride ion anomaly starting 5 days prior to the quake and lasting 10 13 days the anomaly is characterized by cl concentrations 36 above background values this precursory chemical change is attributed to a pre seismic strain change which induced mixing of geochemically different aquifers chloride rich groundwaters are known to rise close 10 km to the alet spring and mixing calculations suggest that a limited inflow of similar waters within the alet hydrologic system is a viable explanation for the chloride ion anomaly this result confirms that mineral springs are promising sites for the search of earthquake geochemical precursors

scaling factors for the rates of production of cosmogenic nuclides for geometric shielding and attenuation at depth on sloped surfaces abstract the decrease in rates of production of cosmogenic nuclides occurs because of shielding of cosmic rays by mountains sloped surfaces and local rock formations that block them when a large part of the sky is blocked this correction is large and requires detailed model calculations this paper considers three geometries a rectangular obstruction a triangular obstruction and a sloped surface other geometries can be considered as a combination of these the results are presented in terms of formulas and graphs so that the reader can easily apply them to common field situations any use of cosmogenic nuclides in the study of geomorphic processes or forms must consider factors that introduce variations in the production of nuclides

ground water radon anomaly before the kobe earthquake in japan radon concentration in ground water increased for several months before the 1995 southern hyogo prefecture kobe earthquake on 17 january 1995 from late october 1994 the beginning of the observation to the end of december 1994 radon concentration increased about fourfold on 8 january 9 days before the earthquake the radon concentration reached a peak of more than 10 times that at the beginning of the observation before starting to decrease these radon changes are likely to be precursory phenomena of the disastrous earthquake

correction of in situ cosmogenic nuclide production rates for geomagnetic field intensity variations during the past 800 000 years we present integrated relative production rates for cosmogenic nuclides in rock surfaces which take into account reported variations of the geomagnetic field intensity during the past 800 000 yr the calculations are based on the model simulating cosmic ray particle interactions with the earth s atmosphere given by masarik and beer simulation of particle fluxes and cosmogenic nuclide production in the earth s atmosphere j geophys res 104 d10 12099 12111 1999 corrections are nearly independent on altitude between sea level and at least 5000 m the correction factors are essentially identical for all stable and radioactive cosmogenic nuclides with half lives longer than a few hundred thousand years at the equator integrated production rates for exposure ages between 40 000 to 800 000 yr are 10 to 12 higher than the present day values whereas at latitudes 40 geomagnetic field intensity variations have hardly influenced in situ cosmogenic nuclide production correction factors for in situ 14c production rates differ from those of longer lived nuclides they are always smaller than 2 because the magnetic field intensity remained rather constant during the past 10 kyr when the major fraction of the 14c extant today was produced

rock fabric pore geometry and mineralogy effects on water transport in fractured dolostones abstract the combined influence of rock fabric pore geometry and mineralogy petrological parameters on transport properties in complex and heterogeneous naturally fractured rocks was studied experimentally as fissure geometry quantification has rarely been addressed in most theoretical studies of transport properties emphasis was placed on the effects of fissure geometry on both non saturated media capillary rise and saturated media permeability we proved that prediction of transport properties in complex rocks is not guaranteed by the estimation of the classic micro structural variables considered in the literature and that accurate prediction can only be attained when petrological parameters are first quantified in depth and then combined principal component analysis and the regression models proposed here clearly demonstrated on the one hand that a meaningful porous network in non saturated media must be modelled with a combination of different geometrical capillary tubes representing the matrix cylindrical and the fissure rectangular prism and on the other hand that in saturated media a well in deep fissure size quantification enabled a more accurate prediction of permeability to be made the experimental data confirm that transport properties and its anisotropy are closely dependent on fissure typology textural characteristics mineralogy and spatial distribution of the whole rock fabric elements enlarged fissures weakly exert capillary suction due to the retarding effect of gravitational forces but they are vital in controlling permeability cracklebreccias with small clasts high dolomite cement content and high inter clast fissure density exhibit strong capillary suction however high calcite cement produces abnormally low rates of capillary rise due to possible pore surface contamination together with a high contact angle effect good agreement between permeability and geometric factors provided a suitable basis for identifying preferred permeable directions additionally we found a critical fissure density which defined the isotropic matrix permeability we also present a new practical and simple linear model relating permeability to capillarity with meaningfully and easily estimated petrological parameters results obtained in the present study demonstrated the correct identification and use of more directly related petrological variables for modelling transport properties moreover the analysis of these results using multivariate analysis is considerably more demanding compared to the conventional approaches

impact of blasting on groundwater composition in a fracture in canada s underground research laboratory groundwater composition in a discrete water bearing fracture in granitic rock at the underground research laboratory manitoba was monitored during a period of underground excavation of adjacent rock to determine the impact of conventional blasting techniques and rock fracturing on the concentration of dissolved constituents this work has relevance to the study of hydrogeochemical anomalies associated with seismic activity short lived anomalies such as decreases in dissolved anion cl f br so4 and gas he rn concentrations and concurrent increases in no3 and o2 concentrations were seen shortly after two blasts located opposite the groundwater sampling site a third blast downstream of the site resulted in variability in dissolved gases concentrations but showed no impact on dissolved anion concentrations the results are compared with various models used to account for hydrogeochemical fluctuations associated with earthquakes the data best fit a general form of the aquifer breaching fluid mixing model in which hydrochemical responses are caused by localized changes in hydraulic conductivity along the plane of a fracture which in turn cause changes in mixing ratio of groundwater at the monitoring site

anomalous chemical changes in well waters and possible relation to earthquakes water level temperature salinity electric conductivity and ph have been measured periodically for several years at three water wells located along a 17 km segment of the san andreas fault between san jaun bautista and cienega winery in central california water samples were collected at the same time for subsequent chemical analyses in the laboratory some sudden large changes in salinity and conductivity were recorded in early march 1980 at the two wells near san juan bautista these changes coincided approximately with the beginning of an episode of increased local seismicity including a magnitude 4 8 earthquake on april 13 analyses of water samples revealed corresponding changes in ion concentrations especially of na sup ca sup mg sup so sup sub 4 sup hco sup sub 3 f sup and cl sup the observed changes may be the result of mixing of waters from different aquifers through cracks developed in the water barriers by a possible crustal strain episode that may have occurred in the study area

plausibility of long distance electrotelluric precursors to earthquakes a systematic analysis of the plausibility of different classes of models which could account for low frequency precursory electrotelluric signals observable at large distances from a large earthquake is carried out first we consider linear models for which either a stationary electrical field is generated by a current dipole in the source volume or a static deformation field results from a precursory strain in the source volume linearly inducing a streaming potential effect near the electrode in the former case only the conjunction of very favorable circumstances may lead to an electrical field larger than 10 mv km at more than 100 km with the constraint that no anomaly exceeds a few volts per kilometer in the source area it indeed requires a powerful electrical dipole current 104 a length 1 km which might be produced by a streaming potential effect associated with the connection of nonhydrostatic fluid reservoirs pore pressure difference up to 100 mpa a two dimensional channeling of the electrical currents from the source to the electrode area which would result from high conductivity horizontal layers and finally a local amplification factor of typically 100 near the electrodes which might be produced by a narrowing of the conductive channel for an elastic long distance interaction an electric field of 10 mv km at a distance 10 times the source length 100 km away from a m 6 earthquake requires a precursory deformation larger than the coseismic deformation if no strong local amplification is considered alternatively nonlinear models are proposed and discussed assuming that the crust is stuffed with small scale local instabilities fractures and nonhydrostatic fluid reservoirs among which a number are close to their instability threshold these instabilities may follow their own evolutionary process inducing sporadic fluid flow and hence streaming potential effect in the vicinity of the electrodes without any relation to a remote tectonic activity however these instabilities may be sensitive to very small changes in the stress field and hence be triggered by the elastic precursory deformation of a remote seismic source this requires that the precursory deformation near the instability is at least larger than the tidal strain 10 7 this necessary condition is met at a distance of up to 10 times the source dimension when the precursory strain source is only 10 of the coseismic deformation provided that the strain source is double the size of the seismic fault itself this model could account for the absence of self potential anomalies related to the earthquake itself as a large proportion of the available instabilities could have been swept away by the precursory strain furthermore with such a model a precursory strain in the source area could induce a detectable change in the background seismic activity over a vast area which may give a new interpretation of the times of increased probability observations for short distances the triggering of fluid instabilities by strain perturbation and the associated streaming potential effect may well be a promising model for explaining low frequency electric and magnetic precursors