tidal diffusivity a mechanism for frontogenesis it is hypothesized that tidal mixing may provide a diffusivity mechanism for frontogenesis it stems from the fact that tidal diffusivity varies in the opposite sense from the water depth so the vertically integrated diffusivity may exhibit a minimum at midshelf thus giving rise to a maximum in the property gradient even in the absence of flow convergence an analytical model assuming a tidal diffusivity dominated by shear dispersion is used to elucidate the mechanism which shows additionally that the front is located at a water depth that is about twice the tidal frictional depth a prediction not inconsistent with some observed fronts the proposed frontogenesis is demonstrated by numerical calculations using the princeton ocean model pom which show the emergence of a front from an initial field of uniform gradient after tides are switched on and the diagnosis of the numerical solution and its parameter dependence has corroborated the analytical model it is suggested moreover that this diffusivity mechanism may be extended to the wind induced mixing to explain the shelfbreak front off of the northeastern united states

implementing the effect of the rupture directivity on psha for the city of istanbul turkey abstract in the present study we improve the probabilistic seismic hazard assessment psha taking into account fault rupture related parameters that sensibly affect the azimuthal variability of the ground motion the study area is the marmara region turkey characterized by one of the highest levels of seismic risk in europe and the mediterranean region the seismic hazard in the city of istanbul is mainly associated with two active fault segments having well defined geometry focal mechanism and rate of activity deterministic dynamic models are also available in this area aochi and ulrich 2015 that aimed at evaluating the seismic potential of the marmara region these models provide the statistical distribution for the hypocenter position which is particularly relevant for rupture directivity the aim of this work is to incorporate all the available information about the seismic potential of the marmara region in a psha framework we use an analytical model for directivity spudich and chiou 2008 spudich et al 2013 to integrate rupture related parameters inside the psha standard procedure because the directivity effect is conditional on the hypocenter position which is not a priori known we assume at first ad hoc gaussian distributions centered in the western eastern or middle part of the two fault segments our results show that the correction for directivity introduces a significant contribution up to 25 of relative increase at 2 s to the hazard maps computed with the standard psha practice given in terms of pseudospectral accelerations having 10 probability of exceedance in 50 years the hazard maps sensibly change when we use the distribution for the hypocenter position informed by the statistical treatment of dynamic simulations thus integrating new variables in the psha in combination with properly informed probability density functions is not only feasible but also recommended for a comprehensive psha

hydrochemical assessment of freshening saline groundwater using multiple end members mixing modeling a study of red river delta aquifer vietnam abstract in this study we evaluated the water quality status especially salinity problems and hydrogeochemical processes of an alluvial aquifer in a floodplain of the red river delta vietnam based on the hydrochemical and isotopic data of groundwater samples n 23 from the kien xuong district of the thai binh province following the historical inundation by paleo seawater during coastal progradation the aquifer has been undergone progressive freshening and land reclamation to enable settlements and farming the hydrochemical data of water samples showed a broad hydrochemical change from na cl through na hco 3 to ca hco 3 types suggesting that groundwater was overall evolved through the freshening process accompanying cation exchange the principal component analysis pca of the hydrochemical data indicates the occurrence of three major hydrogeochemical processes occurring in an aquifer namely 1 progressive freshening of remaining paleo seawater 2 water rock interaction i e dissolution of silicates and 3 redox process including sulfate reduction as indicated by heavy sulfur and oxygen isotope compositions of sulfate to quantitatively assess the hydrogeochemical processes the end member mixing analysis emma and the forward mixing modeling using phreeqc code were conducted the emma results show that the hydrochemical model with the two dimensional mixing space composed of pc 1 and pc 2 best explains the mixing in the study area therefore we consider that the groundwater chemistry mainly evolved by mixing among three end members i e paleo seawater infiltrating rain and the k rich groundwater the distinct depletion of sulfate in groundwater likely due to bacterial sulfate reduction can also be explained by emma the evaluation of mass balances using geochemical modeling supports the explanation that the freshening process accompanying direct cation exchange occurs through mixing among three end members involving the k rich groundwater this study shows that the multiple end members mixing model is useful to more successfully assess complex hydrogeochemical processes occurring in a salinized aquifer under freshening as compared to the conventional interpretation using the theoretical mixing line based on only two end members i e seawater and rainwater

westward propagation of north anatolian fault into the northern aegean timing and kinematics comment and reply based on stratigraphical and structural evidence armijo et al 1999 1 considered that the north anatolian fault has 70 85 km total offset in the marmara region of northwest turkey they also suggested that the fault reached the marmara region 7 5 ma their main stratigraphic evidence is a

propagation of a strike slip plate boundary within an extensional environment the westward propagation of the north anatolian fault we document the establishment of the aegea anatolia eurasia plate boundary in pliocene pleistocene time before 2 ma no localized plate boundary existed north of the aegean portion of the anatolia plate and the shear produced by the motion of anatolia aegea with respect to eurasia was distributed over the whole width of the aegean west anatolian western portion in 4 5 ma a shear zone comparable to the gulf of corinth was formed in the present sea of marmara the initial extensional basins were cut by the strike slip main marmara fault system after 2 5 ma shortly after the plate boundary migrated west of the sea of marmara along the northern border of aegea from the north aegean trough to the gulf of corinth area and to the kefalonia fault there it finally linked with the northern tip of the aegean subduction zone completing the system of plate boundaries delimiting the anatolia aegea plate we have related the change in the distribution of shear from miocene to pliocene to the formation of a re

characterization of vertical mixing at a tidal front on georges bank studies of mixing were done at the northern flank of georges bank in the summer and autumn of 1988 two time series of the evolution and intensity of microstructure were examined over a tidal period in the context of tidal forcing and the evolution of the density and velocity field at the site from the ctd adcp and microstructure observations epsonde on georges bank several interesting features of the mixing processes were found high dissipation and diffusivity regions appear near the bottom of the bank turbulence near the bottom is highest in intensity and reaches farthest from the bottom at peak tidal flow and diminishes in intensity and vertical extent as the flow decreases the thickness of the bottom turbulent layer has its maximum value when the flow is strongest and the stratification is weakest characterization of the dissipation rate and turbulent diffusivities in respect to buoyancy frequency n current shear s richardson number ri and n2 was done dissipation and t showed little dependence on shear or n2 but decreased at larger ri t was found to be higher in regions of higher n2 and increased as n2 increased kt k and k were all highest near the bottom in excess of 10 2m2s 1 and decreased towards the surface there was little suggestion of a dependence of mixing efficiency on s2 ri or n2 but some indication that decreases with decreasing n2

zooplankton distributions and transport across the northeastern tidal front of georges bank tidal fronts are important sites of contact and mixing between zooplankton populations on and off georges bank in the northwest atlantic this study a component of the us globec program examined crossfrontal distributions of zooplankton especially the copepod calanus finmarchicus across the northeastern tidal front of georges bank relative to the tidal cycle frontal structure flow field and day night cycle a unique feature was a precisely executed sampling strategy designed to isolate spatial tidal and day night effects vertically stratified zooplankton sampling was done along tidally coordinated crossfrontal transects and during time series studies at specific locations zooplankton taxa differed in their spatial and vertical distributions relative to the front and the hydrographic structure of the water column there were significant associations between zooplankton assemblages and spatial location depth and water mass zooplankton distributions generally tracked water masses but usually showed crossbank abundance gradients consistent differences between day and night distributions were not apparent for most taxa meroplankton larvae of benthic animals were derived primarily from onbank populations the zooplankton community was advected with the tidal flow crossfrontal distributions characteristic of onbank and offbank flow regimes clearly differentiated tidal phases and interacted with the flow field and topography salinity a proxy for water mass and depth interacted in controlling vertical distributions as tidal forcing sloshed water masses up and down the bank slope some taxa followed isohalines through depth changes while other taxa maintained themselves within a relatively limited depth or salinity regime surface convergence and downwelling tidal upwelling of bottom water and mid depth tidal pumping influenced crossfrontal exchange

paleoseismological and morphological evidence of slip rate variations along the north tabriz fault nw iran northwest iran is characterized by a high level of historical and instrumental seismicity related to the ongoing convergence between the arabian and eurasian plates in this region the main right lateral strike slip fault known as the north tabriz fault ntf forms the central portion of a large crustal fault system called the tabriz fault system tfs the ntf is a major seismic source along which at least three strong and destructive earthquakes have occurred since 858 ad the two most recent destructive seismic events occurred in 1721 ad and 1780 ad rupturing the se and nw fault segments respectively this paper reports paleoseismological and quantitative geomorphologic investigations on the se segment of the ntf between the cities of bostanabad and tabriz these observations help to improve our understanding of the seismic hazard for tabriz city and its surrounding areas our field investigations revealed evidence of successive faulting events since the late quaternary paleoseismic investigations indicate that since 33 5 kyr the se segment of the ntf has experienced at least three major m 7 5 seismic events including the 1721 ad earthquake m 7 6 7 7 along the nw segment of the fault however our results suggest that the amount of strong m 7 5 seismic events during the same period is significantly greater than along the se segment one possible explanation of such a difference in seismic activity is that the late quaternary holocene coseismic slip rate is decreasing along the ntf from the northwest to the southeast this explanation contradicts the former hypothesis of a constant slip rate along the whole length of the ntf in addition more distributed deformation along several parallel fault branches in a wider fault zone of the se segment of the ntf may be considered as additional evidence for the estimation of lower rate of deformation along the fault segment such a slip distribution pattern can explain the existence of smaller 300 m pliocene quaternary cumulative dextral offsets along the se fault segment than the measured cumulative offsets along the nw segment 800 m of the ntf

from transpression to transtension changes in morphology and structure around a bend on the north anatolian fault in the marmara region abstract the east west trending north anatolian fault makes a 17 bend in the western marmara region from a mildly transpressional segment to a strongly transtensional one we have studied the changes in the morphology and structure around this fault bend using digital elevation models field structural geology and multi channel seismic reflection profiles the transpression is reflected in the morphology as the ganos mountain a major zone of uplift 10 km wide and 35 km long elongated parallel to the transpressional ganos fault segment west of this bend flat lying eocene turbidites of the thrace basin are folded upwards against this ganos fault forming a monocline with the ganos mountain at its steep southern limb and the flat lying hinterland farther north at the flat limb the sharp northern margin of the ganos mountain coincides closely with the monoclinal axis the strike of the bedding and the minor and regional fold axes in the eocene turbidites in ganos mountain are parallel to the trace of the ganos fault indicating that these structures as well as the morphology have formed by shortening perpendicular to the north anatolian fault the monoclinal structure of ganos mountain implies that the north anatolian fault dips under this mountain at 50 and this ramp terminates at a decollement at a calculated depth of 8 km east of this fault bend the northward dip of the north anatolian fault is maintained but it has a normal dip slip component this has led to the formation of an asymmetric half graben the tekirdag basin in the western sea of marmara containing a thickness of up to 2 5 km of pliocene to recent syn transform sediments as the ganos uplift is translated eastwards from the transpressional to the transtensional zone it undergoes subsidence by southward tilting however a morphological relic of the ganos uplift is maintained as the steep northern submarine slope of the tekirdag basin the minimum of 3 5 km of fault normal shortening in the ganos mountain and the minimum of 40 km eastward translation of the ganos uplift indicate that the present fault geometry has existed for at least the last 2 million years

palaeoseismology of the north anatolian fault near the marmara sea implications for fault segmentation and seismic hazard we conducted palaeoseismic studies along the north anatolian fault both east and west of the marmara sea to evaluate its recent surface rupture history in relation to the well documented historical record of earthquakes in the region and to assess the hazard of this major fault to the city of istanbul one of the largest cities in the middle east across the 1912 rupture of the ganos strand of the north anatolian fault west of the marmara sea we excavated 26 trenches to resolve slip and constrain the earthquake history on a channel fan complex that crosses the fault at a high angle a distinctive well sorted fine sand channel that served as a marker unit was exposed in 21 trenches totaling over 300 m in length isopach mapping shows that the sand is channelized north of the fault and flowed as an overflow fan complex across a broad fault scarp to the south realignment of the feeder channel thalweg to the fan apex required about 9 1 m of reconstruction study of the rupture history in several exposures demonstrates that this displacement occurred as two large events analysis of radiocarbon dates places the age of the sand channel as post ad 1655 so we attribute the two surface ruptures to the large regional earthquakes of 1766 and 1912 if each was similar in size then about 4 5 m of slip can be attributed to each event consistent with that reported for 1912 farther east we also found evidence for two additional surface ruptures after about ad 900 which probably correspond to the large regional earthquakes of 1063 and 1344 or 1354 these observations suggest fairly periodic occurrence of large earthquakes ri c 283 113 years for the past millennium and a rate of c 16 mm a if all events experienced similar slip we excavated six trenches at two sites along the 1999 izmit rupture to study the past earthquake history along that segment of the north anatolian fault one site located in the township of kosekoy east of izmit revealed evidence for three surface ruptures including 1999 during the past 400 years the other trench was sited in an ottoman canal that was excavated but never completed in 1591 there is evidence for three large surface rupturing events in the upper 2 m of alluvial fill within the canal at that site located only a few kilometres from the kosekoy site one of the past events is almost certainly the large earthquake of 1719 for which historical descriptions of damage are nearly identical to that of 1999 other earthquakes that could plausibly be attributed to the other recognized rupture of the izmit segment are the 1754 1878 or 1894 events all of which produced damage in the region and for which the source faults are poorly known our palaeoseismic observations suggest that the izmit segment of the north anatolia fault ruptures every one and a half centuries or so consistent with the historical record for the region although the time between ruptures may be as short as 35 years if 1754 broke the izmit segment release of about 4 m of seismic slip both west and east of the marmara sea this past century 1912 1999 support the contention that istanbul is at high risk from a pending large earthquake in that historical records suggest that the last large central marmara sea event occurred in 1766 there may be a similar 4 m of accumulated strain across the marmara basin segment of the north anatolian fault

inverse chemical modeling and radiocarbon dating of palaeogroundwaters the tertiary ledo paniselian aquifer in flanders belgium groundwater samples from the ledo paniselian aquifer have been interpreted for chemical reaction patterns 14c age and recharge conditions this confined tertiary aquifer dips nne from its outcrop in belgium toward the north sea over a length of 50 km conventional 14c ages of the water samples range from 3 to over 40 ka inverse chemical modeling was done to correct the 14c ages for the chemical reactions in the aquifer while accounting for changes in the recharge water quality during the holocene and late pleistocene the aquifer shows a zonal pattern with going upstream na k nh4 mg and ca hco3 water types the pattern is a result of freshening ca displaces the saline cations na k nh4 and mg from the aquifer s cation exchange complex in a chromatographic sequence the loss of ca2 from solution by cation exchange is by far the most important reaction for dissolution of calcite which increases the apparent 14c age of the water samples the 14c age furthermore depends on open closed conditions of calcite dissolution and co2 gas exchange and co2 pressure in the recharge area it is shown that 13c and co2 pressure in a soil are interrelated and that the changes in co2 pressure can be included in an inverse model which considers variations in infiltration water quality the overall correction for 14c age is obtained by inverse modeling of water quality and 13c with optimization on co2 pressure in recharge water using phreeqc parkhurst 1995 the optimized co2 pressure for the recharge area varies with age and is generally lower in the water samples with an age above 13 ka the lower co2 pressure is corroborated by lower 18o values of the water

a 3 d prognostic numerical model study of the georges bank ecosystem part i physical model abstract the influence of tidal forcing and tidal and wind mixing on circulation and stratification over georges bank and adjacent regions in the gulf of maine has been examined using the 3 d semi implicit version of the blumberg and mellor 1987 primitive equation ocean circulation model the numerical domain covered the gulf of maine georges bank region with an open boundary starting at the new jersey coast and ending at the nova scotia coast with increased spatial resolution over georges bank numerical experiments were conducted using both smoothed and non smoothed high resolution 15 s bottom topography the model was forced by specifying the m 2 elevation and phase on the open boundary and several forms of the bottom roughness parameter z o were used the model provided a reasonable simulation of the m 2 tidal elevations and currents the model when run as an initial value problem with early summer stratification exhibited tidal mixing fronts around the 40 60 m isobath over georges bank and nantucket shoals and 100 m isobath on brown bank the formation of these tidal mixing fronts significantly enhanced the along isobath tidal rectified current over georges bank and the other two shoal regions a cool water band developed within the frontal zone along the eastern and southern flanks of georges bank and nantucket shoal and it became cooler owing to wind mixing and upwelling as a mean summer wind stress was added tidal mixing and turbulent dissipation varied in time asymmetrically over georges bank over georges bank tidal mixing was generally characterized as a local 1 d balance between turbulent shear production and dissipation the spatial structure of the tidal residual flow and local turbulent dissipation rate depended critically on the spatial resolution of the bottom topography and the spatial distribution of z 0 analysis of the 3 d momentum balance and the residual flow over the center of georges bank indicates that earlier results based on a 2 d cross bank model correctly captured the basic dynamics of stratified tidal rectification and tidal mixing in this idealized model setting

vertical structure of turbulence on the southern flank of georges bank microstructure and acoustic doppler current profiler measurements were taken at two sites on georges bank in a shallow 45 m well mixed region on top of the bank and in a deeper 75 m more stratified region on the southern flank each site was visited twice april 25 to may 3 1995 and june 6 16 1995 at both sites the dominant variability in the turbulent kinetic energy dissipation rate e was related to the semidiurnal m2 tide in the well mixed lower portions of the water column a phase delay was observed between e and the current speed the delay increased with height above the bottom there was also a depth dependent phase delay in the square of the vertical shear of horizontal velocity s2 of the m2 component this phase lag has a depth dependence similar to that found for e which suggests that the turbulent mixing is locally generated by the current shear as opposed to having propagated from the boundary

rupture characteristics of the a d 1912 murefte ganos earthquake segment of the north anatolian fault western turkey abstract the ganos fault is the westernmost segment of the north anatolian fault naf that generated the 9 august 1912 murefte ganos earthquake mw 7 4 we study the 1912 earthquake characteristics using co seismic fault slip and fault segmentation coupled with an analysis of historical seismic records surface ruptures with small releasing and restraining structures and 1 5 to 5 5 m right lateral offsets have been measured at 45 sites of the onland 45 km long fault section similar structures are delineated by fresh fault scarps and prominent pull apart basins in the sea of marmara and saros bay a second shock with mw 6 8 occurred on 13 september 1912 implying 20 to 40 km long rupture the damage distribution and analysis of seismic records suggest an epicenter located further west near saros bay which indicates the location of western termination of the 9 august rupture our modeling of historical seismic records reveals a relative source time function between the two events and indicates a 40 second rupture duration in agreement for a 120 30 km long fault rupture for the 9 august shock an estimated total rupture length of 150 30 km for the two earthquakes combined with onshore and offshore fault segmentation allow us to better constrain the western limit of the marmara sea seismic gap and related potential for producing a large earthquake that was sharply increased by the devastating 1999 izmit earthquake in the east

does ocean turbulence peak at the equator revisited abstract in spite of the effects of several form of temporal variability that tend to mask geographical patterns in turbulence intensity our evidence indicates that the turbulence is enhanced above the equatorial undercurrent in comparison to latitudes north and south of it this evidence consists of three meridional transects of micro structure observations across the equator at 140 w in 1984 and 1987 and at 110 w in 1987 along with an equatorial station at 140 w and a longitudinal transect along the equator from 140 w to 110 w all three meridional transects show a peak in averaged estimates of the turbulent kinetic energy dissipation rates at the equator although in 1984 the peak was not significant at the 95 level the major sources a temporal variability were the diurnal buoyancy flux variation and the wind stress variations which had a typical period of a few days after the diurnal variability is removed by averaging it can be shown that for similar wind stress is larger over the un

holocene slip rate of the north anatolian fault beneath the sea of marmara abstract the north anatolian fault naf is a major continental transform system that extends e w across turkey for over 1600 km separating the anatolian and eurasian plates a portion of its northern branch runs below the sea of marmara this portion constitutes a seismic gap because the last destructive earthquakes occurred at the western 1912 ganos earthquake m 7 4 and eastern 1999 izmit and duzce earthquakes m w 7 4 7 2 edges of the marmara basin it is likely that fault ruptures will fill this gap in the next decades this region of the north anatolian fault is critical to our understanding of fault interactions stress buildup during seismic cycle and seismic hazard in the istanbul area we obtained high resolution acoustic images of the naf in the floor of the eastern marmara sea gulf of izmit and measured fault related offsets of 14 c dated subseafloor channels and paleoshorelines the resulting average slip rate on the fault is 10 mm year for the last 10 kyr this is less than half the total anatolia eurasia relative motion estimated at 24 mm year for the last 10 years from satellite geodetic measurements we conclude that either much of the strike slip motion along this branch of the naf did not occur on the main fault segment or the slip rate increased recently or both these results affect kinematic models of the naf and assessments of seismic hazard for the city of istanbul and the surrounding region

holocene faulting and earthquake recurrence along the serghaya branch of the dead sea fault system in syria and lebanon an edited version of this paper was published in geophysical journal international by blackwell publishing blackwell publishing retains the copyright copyright 2003 blackwell publishing see also http www blackwell synergy com doi abs 10 1046 j 1365 246x 2003 01933 x http atlas geo cornell edu deadsea publications gomez2003 gji htm

the surface rupture and slip distribution of the 17 august 1999 izmit earthquake m 7 4 north anatolian fault the 17 august 1999 izmit earthquake occurred on the northern strand of the north anatolian fault zone the earthquake is associated with a 145 km long surface rupture that extends from southwest of duzce in the east to west of hersek delta in the west detailed mapping of the surface rupture shows that it consists of five segments separated by releasing step overs herein named the hersek karamursel golcuk izmit sapanca lake sapanca akyazi and karadere segments from west to east respectively the hersek segment which cuts the tip of a large delta plain in the western end of the rupture zone has an orientation of n80 the n70 80 e trending karamursel golcuk segment extends along the linear southern coasts of the izmit gulf between karamursel and golcuk and produced the 470 cm maximum displacement in golcuk the northwest southeast striking golcuk normal fault between the karamursel golcuk and izmit sapanca segments has 2 3 m maximum vertical displacement the maximum dextral offset along the izmit sapanca lake segment was measured to be about 3 5 m and its trend varies between n80 e and east west the sapanca akyazi segment trends n75 85 w and expresses a maximum displacement of 5 2 m the karadere segment trends n65 e and produced up to 1 5 m maximum displacement the karadere and sapanca akyazi segments form fan shape or splaying ruptures near their eastern ends where the displacement also diminished

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

a new groundwater radiocarbon correction approach accounting for palaeoclimate conditions during recharge and hydrochemical evolution the ledo paniselian aquifer belgium abstract the particular objective of the present work is the development of a new radiocarbon correction approach accounting for palaeoclimate conditions at recharge and hydrochemical evolution relevant climate conditions at recharge are atmospheric pco 2 and infiltration temperatures influencing c isotope concentrations in recharge waters the new method is applied to the ledo paniselian aquifer in belgium this is a typical freshening aquifer where recharge takes place through the semi confining cover of the bartonian clay besides cation exchange which is the major influencing process for the evolution of groundwater chemistry particularly in the bartonian clay also mixing with the original porewater solution fossil seawater occurs in the aquifer recharge temperatures were based on noble gas measurements potential infiltration water compositions for a range of possible pco 2 temperature and calcite dissolution system conditions were calculated by means of phreeqc then the sampled groundwaters were modelled starting from these infiltration waters using the computer code netpath and considering a wide range of geochemical processes fitting models were selected on the basis of correspondence of calculated 13 c with measured 13 c the 14 c modelling resulted in residence times ranging from holocene to pleistocene few hundred years to over 40 ka and yielded consistent results within the uncertainty estimation comparison was made with the 13 c and fontes and garnier correction models that do not take climate conditions at recharge into account to date these are considered as the most representative process oriented existing models yet differences in calculated residence times of mostly several thousands of years up to 19 ka are revealed with the newly calculated ages being mostly though not always younger not accounting for climate conditions at recharge pco 2 and temperature is thus producing substantial error on deduced residence times the derived 14 c model ages are correlated with he concentrations measured in the groundwater of the aquifer the obtained residence times show a gap between about 14 and 21 ka indicating possible permafrost conditions which inhibited any groundwater recharge

morphology displacement and slip rates along the north anatolian fault turkey 1 geological and geomorphological offsets at different scales are used to constrain the localization of deformation total displacement and slip rates over various timescales along the central and eastern north anatolian fault naf in turkey the naf total displacement is reevaluated using large rivers valleys 80 15 km and structural markers pontide suture 85 25 km tosya vezirkopru basins 80 10 km these suggest a neogene slip rate of 6 5 mm yr over 13 myr the river network morphology shows offsets at a range of scales 20 m to 14 km across the main fault trace and is also used to estimate the degree to which deformation is localized at a smaller scale the morphology associated with small rivers is offset by 200 m along the naf the age of these features can be correlated with the holocene deglaciation and a slip rate of 18 3 5 mm yr is determined this is consistent with a rate of 18 5 mm yr deduced independently from the 14c dating of stream terrace offsets over the short term gps data gives a similar rate of 22 3 mm yr all our results tend to show that most of the deformation between the anatolian and eurasian lithospheric plates has been accommodated along or very close to the active trace of the naf the difference between the neogene and the holocene slip rate may be due to the recent establishment of the current plate geometry after the creation of the naf

the front on the northern flank of georges bank in spring 2 cross frontal fluxes and mixing buoyancy fluxes are downward and most intense reaching values of 5 10 7 w kg near the bottom at the edge of the bank and decrease both on and off bank horizontal crossbank buoyancy fluxes are partitioned into mean tidal pumping and nontidal eddy components and are computed as a function of cross isobath vertical position by averaging in the along isobath direction the tidal pumping component is dominant over most of the cross bank section with a peak value of 1 10 4 w kg directed off bank near the bank edge a diagnosed tidal vertical velocity field is used with mean buoyancy gradients to compute the along isopycnal skew flux the horizontal component of this skew flux has similar spatial structure and magnitude to that of the observed tidal pumping flux the divergent component of the skew flux at depths above the bottom boundary layer appears to be convergent north of the bank edge and divergent at the bank edge suggesting that tidally driven advective processes drive buoyant bank water downward and off bank at mid depth and force the upwelling of deep dense water near the bottom at the bank edge index terms 4528 oceanography physical fronts and jets 4568 oceanography physical turbulence diffusion and mixing processes 4560 oceanography physical surface waves and tides 1255 4544 oceanography physical internal and inertial waves keywords georges bank tidal mixing front globec internal tide skew eddy flux turbulent mixing

a 2500 yr long paleoseismologic record of large infrequent earthquakes on the north anatolian fault at cukurcimen turkey paleoseismologic trenches excavated across the north anatolian fault near the village of cukurcimen in north central turkey yield a complete record of surface ruptures for the past 2500 yr the trenches provide mutually consistent evidence for the timing of the five most recent surface ruptures at the site as well as at least two older events these are interpreted as 1 the historic 1939 m w 7 9 earthquake 2 the historic 1254 a d earthquake 3 the historic 1045 a d earthquake 4 an earthquake that probably occurred late in the interval between 250 and 540 a d possibly the historic 499 a d earthquake and 5 an earthquake that occurred sometime between 770 and 50 b c and probably between 230 and 50 b c one additional earthquake occurred sometime between 1450 and 800 b c and at least one other surface rupture occurred between 2880 and 200 b c but the stratigraphic section at the site was not completely exposed for sediments older than 2500 yr as a result it is unclear whether the oldest event horizons represent a single earthquake or multiple events our findings when coupled with other published results and the historical record enable us to construct a space time history of earthquakes along the north anatolian fault the most striking aspects of this analysis are 1 the rarity of earthquakes at any given place along the fault suggesting that the fault typically ruptures in large infrequent events 2 earthquake occurrence is relatively temporally regular with inter event times that range from 200 to 900 yr and vary by a factor of only 3 4 and 3 almost the entire length of the north anatolian fault ruptured in short lived clusters of activity in the seventeenth to eighteenth centuries and in the tenth to twelfth centuries similar to the twentieth century sequence the magnitude and sequence of the individual ruptures however have varied considerably between clusters moreover the paleoseismologic and historical data indicate that the north anatolian fault does not always rupture in sequences similar to the twentieth century cluster these results suggest that the relatively regular recurrence of rare large magnitude earthquakes may be the expected mode of earthquake occurrence on mature strike slip faults in settings where such faults are structurally isolated from other major seismic sources

a new correction model for 14c ages in aquifers with complex geochemistry application to the neogene aquifer belgium abstract the objective of this paper is to build a general correction model that takes into account all the different radiocarbon dilution reactions and resolving the processes that are geochemically aging the groundwater in the neogene aquifer for this 13 c and radiocarbon in groundwater are investigated with their relationship to other chemical components in groundwater the 13 c values in the neogene aquifer are influenced by various geochemical reactions like calcite dissolution oxidation of organic matter and methanogenesis calcite dissolution and ch 4 production increase 13 c while the oxidation of organic matter decreases 13 c in the groundwater the reactions that modify 13 c also influence the 14 c activity due to the complex geochemical environment existing correction models are not applicable to this situation a correction model for initial 14 c activity is formulated in which the different c sources that influence 14 c activity are taken into account it is observed that recent dissolved organic matter plays an important role in redox reactions the corrected 14 c ages lie between 0 792 and 6 425 ka representing the maximum age if a part of the organic matter that oxidises is fossil the determined age will represent an overestimated age

reaction transport modelling of a freshening aquifer tertiary ledo paniselian aquifer flanders belgium abstract the semi confined ledo paniselian eocene aquifer in flanders belgium is recharged in the areas with higher topography where it is covered by the bartonian clay initial conditions in these sediments were marine hydrogeochemical modelling of the groundwater type distribution in the aquifer with a reaction transport model considers recharge of fresh cahco3 water by downward flow through the overlying clay in the aquifer in an upstream direction progressively more freshened water types are found a typical nahco3 type occurs upstream of the brackish fresh water interface the different stages of cation exchange produce a chromatographic sequence of groundwater types which agrees well with observations cation exchange processes occurring mainly in the percolated clay result in a na increase and peaks of k nh 4 and mg2 in the aquifer which are spatially separated as a result of groundwater flow calcite equilibrium gypsum dissolution in the clay and sulphate reduction in the aquifer have also been included in the modelling

groundwater flow system as an archive of palaeotemperature noble gas radiocarbon stable isotope and geochemical study in the pannonian basin hungary abstract to establish the increase in temperature and the time span of the transition between the late glacial maximum lgm and the holocene the noble gas content 18 o 2 h 13 c values 3 h and 14 c activity and chemistry were studied in a groundwater flow system in quaternary sediments in hungary the study area is a sub basin of the pannonian basin where the c isotope ratios are not influenced by carbonate reactions along the flow path because the only water rock interaction is ion exchange the 18 o and 2 h values indicate a cold infiltration period followed by warming and finally warm temperature conditions the noble gas data show that the average infiltration temperature was 3 3 c in the cold 12 9 c in the warm and intermediate in the transitional stage using the noble gas temperatures geochemical batch modelling was performed to simulate the chemical processes based on the geochemical model 13 c and 14 c 0 initial radiocarbon activity in the recharging water were calculated transport modelling was used to simulate the distribution of chemical components 18 o 2 h and 14 c 0 along the flow path it was found that the main processes determining the chemical composition of the groundwater were dissolution precipitation of calcite and dolomite during infiltration near the surface and ion exchange along the flow path in the recharge area the 13 c and 14 c 0 were controlled by dissolution and precipitation of carbonate minerals c speciation and fractionation processes all these processes were influenced by the recharge temperature ngts calculated from the dissolved noble gas concentrations showed an average of 3 3 c for cold and 12 9 c for warm infiltration i e for the lgm and for the holocene the temperature difference was thus 9 1 0 8 c which is one of the largest degree of warming detected by noble gases so far the alkalinity indicates that carbonate reactions were unimportant along the flow path owing to the temperature dependence of the equilibrium constants temperature conditions during infiltration have to be taken into consideration in radiocarbon age calculation dispersive transport along the flow path modified the chemical and isotopic composition of infiltrated water the contribution of the old pore water which was free of the 14 c isotope resulted in uncertainties in radiocarbon age determination it was concluded that determination of the radiocarbon age or mean residence time requires detailed knowledge of the hydraulic conditions of groundwater

measurements of the turbulent energy dissipation rate e and an evaluation of the dispersion process of the changjiang diluted water in the east china sea 1 the large amount of fresh water discharged from changjiang spreads over the east china sea continental shelf as low salinity water particularly in the summer season to understand the primary production in the east china sea it is necessary to clarify the dispersion process of the changjiang diluted water cdw since the high production area appears to cover the cdw in this study the dispersion process of the cdw was evaluated through the estimation of the turbulent energy dissipation rate e in the cdw and calculation of the divergence in the cdw using satellite tracked drifters a large value of e was observed just above the bottom and in the surface layer whose magnitude was sometimes greater than 10 7 w kg 1 on the other hand a small value of e less than 10 8 w kg 1 was found just beneath the cdw the small value of e leads to a small value of the vertical eddy diffusivity of less than 10 5 m 2 s 1 the vertical advection of the bottom water is likely to be a major process for increasing the salinity since the horizontal diffusion would not play a significant role if the usual magnitude of the horizontal diffusivity is assumed calculation of divergence in the surface layer using the drifters data also suggests that upward velocity of o 10 5 m s 1 over the cdw area is expected the vertical transport from the bottom layer could increase the salinity of the cdw and also carry the nutrients into the euphotic zone resulting in biological production

helium accumulation in groundwater ii a model for the accumulation of the crustal 4he degassing flux abstract a model of 4 he accumulation in a confined aquifer is presented which includes in situ production and a crustal degassing flux of 4 he into the bottom of a confined aquifer the model is consistent with the measurements of 4 he concentration in the great artesian basin australia torgersen and clarke 1985 and also with the measurements of 4 he concentration in the auob sandstone of namibia heaton 1981 the measured value of the crustal degassing flux of 4 he from these two areas is comparable with the 4 he degassing flux calculated from the atmospheric budget of 4 he wasserburg et al 1963 ozima and podosek 1983 a literature review suggests that a crustal degassing 4 he source may account for the 4 he accumulation in many other groundwater systems it is concluded from the literature review the detailed modelling of 4 he accumulation in gab and the auob sandstone and the atmospheric budget that crustal degassing of 4 he may be a common and widespread phenomena

paleoseismology of the north anatolian fault at guzelkoy ganos segment turkey size and recurrence time of earthquake ruptures west of the sea of marmara 1 the ganos fault is the westernmost segment of the north anatolian fault that experienced the mw 7 4 earthquake of 9 august 1912 the earthquake revealed 45 km long of surface ruptures inland trending n70 e and 5 5 m of maximum right lateral offset near guzelkoy the long term deformation of the fault is clearly expressed by several pull apart basins and sag ponds pressure and shutter ridges and offset streams in parallel with detailed geomorphologic investigations we measured co seismic and cumulative displacements along the fault and selected the guzelkoy site for paleoseismology a microtopographic survey at the site yields 10 5 0 5 m and 35 4 1 5 m cumulative lateral offsets of stream channels and geomorphologic features seven paleoseismic parallel and cross fault trenches document successive faulting events and provide the timing of past earthquakes on the ganos fault segment radiocarbon dating of successive colluvial wedges in trench t1 and the fresh scarplet above probably 1912 surface rupture indicate the occurrence of three faulting events since the 14th century parallel trenches 3 5 6 and 7 expose paleo channels and show a cumulative right lateral offset of 16 5 1 5 m next to the fault and 21 3 1 5 m total channel deflection radiocarbon dating of past channel units and fault scarp related colluvial deposits imply an average 17 5 mm year slip rate and 323 142 years recurrence interval of large earthquakes during the last 1000 years on the ganos fault the succession of past faulting events and inferred slip rate west of the marmara sea provide more constraint on the long term faulting behavior in the seismic gap of the north anatolian fault and may contribute to a better seismic hazard assessment in the istanbul region

a 40 ka record of temperature and permafrost conditions in northwestern europe from noble gases in the ledo paniselian aquifer belgium the ledo paniselian aquifer in belgium offers unique opportunities to study periglacial groundwater recharge during the last glacial maximum lgm as it was located close to the southern boundary of the ice sheets at that time groundwater residence times determined by 14c and 4he reveal a sequence of holocene and pleistocene groundwaters and a gap between about 14 and 21 ka indicating permafrost conditions which inhibited groundwater recharge in this paper a dataset of noble gas measurements is used to study the climatic evolution of the region the derived recharge temperatures indicate that soil temperatures in the periods just before and after the recharge gap were only slightly above freezing supporting the hypothesis that permafrost caused the recharge gap the inferred glacial cooling of 9 5 c is the largest found so far by the noble gas method yet compared to other palaeoclimate reconstructions for the region recharge temperatures deduced from noble gases for the cold periods tend to be rather high most likely this is due to soil temperatures being several degrees higher than air temperatures during periods with extended snow cover thus the noble gas derived glacial cooling of 9 5 c is only a lower limit of the maximum cooling during the lgm some samples younger than the recharge gap are affected by degassing possibly related to gas production during recharge in part of the recharge area especially during times of melting permafrost the findings of this study such as the occurrence of a recharge gap and degassing related to permafrost and its melting are significant for groundwater dynamics and geochemistry in periglacial areas copyright 2010 john wiley sons ltd

seismic hazard in the marmara sea region following the 17 august 1999 izmit earthquake on 17 august 1999 a destructive magnitude 7 4 earthquake occurred 100 km east of istanbul near the city of izmit on the north anatolian fault this 1 600 km long plate boundary 1 2 slips at an average rate of 2 3 cm yr 1 refs 3 5 and historically has been the site of many devastating earthquakes 6 7 this century alone it has ruptured over 900 km of its length 6 models of earthquake induced stress change 8 combined with active fault maps 9 had been used to forecast that the epicentral area of the 1999 izmit event was indeed a likely location for the occurrence of a large earthquake 9 10 here we show that the 1999 event itself significantly modifies the stress distribution resulting from previous fault interactions 9 10 our new stress models take into account all events in the region with magnitudes greater than 6 having occurred since 1700 ref 7 as well as secular interseismic stress change constrained by gps data 11 these models provide a consistent picture of the long term spatio temporal behaviour of the north anatolian fault and indicate that two events of magnitude equal to or greater than the izmit earthquake are likely to occur within the next decades beneath the marmara sea south of istanbul

paleoearthquakes of the duzce fault north anatolian fault zone insights for large surface faulting earthquake recurrence 1 the 12 november 1999 mw 7 1 earthquake ruptured the duzce segment of the north anatolian fault zone and produced a 40 km long surface rupture to improve knowledge about earthquake recurrence on this fault we undertook paleoseismological trench investigations we found evidence for repeated surface faulting paleoearthquakes predating the 1999 event during the past millennium dating was based on radiocarbon 210pb analyses and archaeological considerations in addition to the 1999 earthquake prior surface faulting earthquakes are dated as follows a d 1685 1900 possibly end of 19th century a d 1495 1700 and a d 685 1020 possibly a d 890 1020 the a d 967 and a d 1878 historical earthquakes are good candidates to have ruptured the duzce fault correlating with the oldest and penultimate paleoearthquakes no obvious correlation for the third paleoearthquake a d 1495 1700 exists these results shows that the duzce fault considerably participates along with the parallel mudurnu fault sections in the seismogenic deformation taking place along this part of the north anatolian fault four events since a d 685 1020 possibly a d 890 1020 would yield an average recurrence time for the duzce fault of 330 430 years possibly 330 370 years the three most recent earthquakes including 1999 occurred within 500 years merging results from other paleoseismological studies along the duzce fault show a consistency of results and yields average recurrence times for the past 2000 years of 320 390 years assuming that the 1999 slip 2 7 m average 5 m maximum is representative of the behavior of this fault the above recurrence times yield a reference figure of fault slip rate in the range 6 9 15 6 mm a

a late holocene slip rate for the central north anatolian fault at tahtakopru turkey from cosmogenic 10be geochronology implications for fault loading and strain release rates 1 measurement of a stream offset and cosmogenic dating 10be of the alluvial surface into which the stream incised yield a preferred late holocene slip rate of 18 6 3 5 3 3 mm a 1 for the central part of the north anatolian fault naf at tahtakopru turkey use of variable cosmogenic production rate vpr models yields a slightly slower rate of 16 4 6 4 4 5 mm a 1 the offset drainage karanlik dere which flows southward almost perpendicular to the east west trace of the naf at the site is displaced right laterally by 55 10 m with no vertical displacement a 10be age of 3 ka 3 5 ka vpr from the top of a boulder on the best preserved part of the incised alluvial surface provides the most reliable maximum age for the onset of incision 11 10be ages from cobbles collected from the cultivated surface to the south yield younger ages consistent with exhumation erosion and mechanical mixing during plowing our 18 6 3 5 3 3 mm a 1 rate is similar to other geologic slip rates measured along the naf all of which cluster between 15 and 20 mm a 1 over a wide range of 103 105 timescales all of these geological rates however are slower than the 25 2 mm a 1 short term rate of elastic strain accumulation measured geodetically this disparity suggests the possibility that the naf is experiencing a strain transient in which the lower crust beneath the fault is deforming faster than its long term rate

a graphical method to evaluate predominant geochemical processes occurring in groundwater systems for radiocarbon dating a graphical method is described for identifying geochemical reactions needed in the interpretation of radiocarbon age in groundwater systems graphs are constructed by plotting the measured 14c 13c and concentration of dissolved inorganic carbon and are interpreted according to specific criteria to recognize water samples that are consistent with a wide range of processes including geochemical reactions carbon isotopic exchange 14c decay and mixing of waters the graphs are used to provide a qualitative estimate of radiocarbon age to deduce the hydrochemical complexity of a groundwater system and to compare samples from different groundwater systems graphs of chemical and isotopic data from a series of previously published groundwater studies are used to demonstrate the utility of the approach ultimately the information derived from the graphs is used to improve geochemical models for adjustment of radiocarbon ages in groundwater systems

submarine fault scarps in the sea of marmara pull apart north anatolian fault implications for seismic hazard in istanbul earthquake scarps associated with recent historical events have been found on the floor of the sea of marmara along the north anatolian fault naf the marmarascarps cruise using an unmanned submersible rov provides direct observations to study the fine scale morphology and geology of those scarps their distribution and geometry the observations are consistent with the diversity of fault mechanisms and the fault segmentation within the north marmara extensional step over between the strike slip ganos and izmit faults smaller strike slip segments and pull apart basins alternate within the main step over commonly combining strike slip and extension rapid sedimentation rates of 1 3 mm yr appear to compete with normal faulting components of up to 6 mm yr at the pull apart margins in spite of the fast sedimentation rates the submarine scarps are preserved and accumulate relief sets of youthful earthquake scarps extend offshore from the ganos and izmit faults on land into the sea of marmara our observations suggest that they correspond to the submarine ruptures of the 1999 izmit mw 7 4 and the 1912 ganos ms 7 4 earthquakes while the 1999 rupture ends at the immediate eastern entrance of the extensional cinarcik basin the 1912 rupture appears to have crossed the ganos restraining bend into the sea of marmara floor for 60 km with a right lateral slip of 5 m ending in the central basin step over from the gulf of saros to marmara the total 1912 rupture length is probably about 140 km not 50 km as previously thought the direct observations of submarine scarps in marmara are critical to defining barriers that have arrested past earthquakes as well as defining a possible segmentation of the contemporary state of loading incorporating the submarine scarp evidence modifies substantially our understanding of the current state of loading along the naf next to istanbul coulomb stress modeling shows a zone of maximum loading with at least 4 5 m of slip deficit encompassing the strike slip segment 70 km long between the cinarcik and central basins that segment alone would be capable of generating a large magnitude earthquake mw 7 2 other segments in marmara appear less loaded

slip distribution along the north anatolian fault associated with the large earthquakes of the period 1939 to 1967 abstract between 1939 and 1967 six large fault ruptures formed a westward migrating sequence of events along a 900 km long nearly continuous portion of the north anatolian fault for these events the 1939 erzincan 1942 niksar erbaa 1943 tosya 1944 bolu gerede 1957 abant and 1967 mudurnu valley earthquakes i have compiled a record of dextral slip which contains nearly 100 points these data indicate that the amount of slip is irregularly distributed along the 1939 to 1967 rupture zone the maximum slip 7 5 m occurred during the 1939 earthquake in the eastern 150 km of the 900 km long rupture zone dextral offsets diminish very abruptly eastward but very gradually westward the rate of westward decrease in the 1939 to 1967 offsets is only slightly greater than the rate of westward decrease of post miocene displacement along the north anatolian fault this suggests that westward decrease in slip can be expected to be a general characteristic of earthquake ruptures along the north anatolian fault in the future nevertheless within the 1939 to 1967 slip distribution there are three regions that had less slip than the neighboring regions these i interpret as possible sites of large future earthquakes one of these seismic gaps has already experienced another earthquake in 1951 and subsequent creep

bottom stress estimates from vertical dissipation rate profiles on the continental shelf abstract measurements of the near bottom distribution of the turbulent dissipation rate on the continental shelf west of vancouver island are used to calculate bottom stress a free failing vertical profiler with microstructure shear probes was used to measure the dissipation rate from near the surface to within 0 15 m of the bottom the shear probes measure velocity gradients at scales within the viscous subrange of the turbulence and therefore directly measure the rate at which kinetic energy is dissipated by viscosity friction velocities are computed from the formula uast z where the dissipation rate is measured in the constant stress layer the technique is more reliable than estimates of the dissipation rate obtained by fitting spectral slopes to velocity spectra at scales in the inertial subrange near bottom current measurements indicate that the bottom stress values obtained from the turbulent measurements are well correlated with the current magnitude an estimate of the drag coeff

a review of single sample based models and other approaches for radiocarbon dating of dissolved inorganic carbon in groundwater abstract numerous methods have been proposed to estimate the pre nuclear detonation 14c content of dissolved inorganic carbon dic recharged to groundwater that has been corrected adjusted for geochemical processes in the absence of radioactive decay 14c0 a quantity that is essential for estimation of radiocarbon age of dic in groundwater the models approaches most commonly used are grouped as follows 1 single sample based models 2 a statistical approach based on the observed curved relationship between 14c and 13c data for the aquifer and 3 the geochemical mass balance approach that constructs adjustment models accounting for all the geochemical reactions known to occur along a groundwater flow path this review discusses first the geochemical processes behind each of the single sample based models followed by discussions of the statistical approach and the geochemical mass balance approach finally the applications advantages and limitations of the three groups of models approaches are discussed the single sample based models constitute the prevailing use of 14c data in hydrogeology and hydrological studies this is in part because the models are applied to an individual water sample to estimate the 14c age therefore the measurement data are easily available these models have been shown to provide realistic radiocarbon ages in many studies however they usually are limited to simple carbonate aquifers and selection of model may have significant effects on 14c0 often resulting in a wide range of estimates of 14c ages of the single sample based models four are recommended for the estimation of 14c0 of dic in groundwater pearson s model ingerson and pearson 1964 pearson and white 1967 han plummer s model han and plummer 2013 the iaea model gonfiantini 1972 salem et al 1980 and oeschger s model geyh 2000 these four models include all processes considered in single sample based models and can be used in different ranges of 13c values in contrast to the single sample based models the extended gonfiantini zuppi model gonfiantini and zuppi 2003 han et al 2014 is a statistical approach this approach can be used to estimate 14c ages when a curved relationship between the 14c and 13c values of the dic data is observed in addition to estimation of groundwater ages the relationship between 14c and 13c data can be used to interpret hydrogeological characteristics of the aquifer e g estimating apparent rates of geochemical reactions and revealing the complexity of the geochemical environment and identify samples that are not affected by the same set of reactions processes as the rest of the dataset the investigated water samples may have a wide range of ages and for waters with very low values of 14c the model based on statistics may give more reliable age estimates than those obtained from single sample based models in the extended gonfiantini zuppi model a representative system wide value of the initial 14c content is derived from the 14c and 13c data of dic and can differ from that used in single sample based models therefore the extended gonfiantini zuppi model usually avoids the effect of modern water components which might retain bomb pulse signatures the geochemical mass balance approach constructs an adjustment model that accounts for all the geochemical reactions known to occur along an aquifer flow path plummer et al 1983 wigley et al 1978 plummer et al 1994 plummer and glynn 2013 and includes in addition to dic dissolved organic carbon doc and methane ch4 if sufficient chemical mineralogical and isotopic data are available the geochemical mass balance method can yield the most accurate estimates of the adjusted radiocarbon age the main limitation of this approach is that complete information is necessary on chemical mineralogical and isotopic data and these data are often limited failure to recognize the limitations and underlying assumptions on which the various models and approaches are based can result in a wide range of estimates of 14c0 and limit the usefulness of radiocarbon as a dating tool for groundwater in each of the three generalized approaches single sample based models statistical approach and geochemical mass balance approach successful application depends on scrutiny of the isotopic 14c and 13c and chemical data to conceptualize the reactions and processes that affect the 14c content of dic in aquifers the recently developed graphical analysis method is shown to aid in determining which approach is most appropriate for the isotopic and chemical data from a groundwater system

the north anatolian fault in the sea of marmara 1 using the detailed geometry and tectonics of the main marmara fault that connects the gulf of izmit fault with the ganos fault established by le pichon et al 2001 and the new gps data set recently analyzed by meade et al 2002 we confirm the existence of a marmara block delimited to the north by the northern branch of the north anatolian fault the marmara branch and to the south by the southern branch the kinematics of this block indicate that the marmara branch that crosses the sea of marmara is close to pure dextral strike slip at a rate of 23 mm yr on its whole length the short cinarcik section is the only one where a significant extensional component is predicted a simple kinematic model accounts for slip partitioning there with 8 10 mm yr of extension to the south of the basin and 23 mm yr of dextral strike slip along the northern cinarcik margin the new gps data demonstrate the existence of important asymmetric elastic loading along the main marmara fault that may have significant implications for the seismotectonics of the area the expected future large earthquake may rupture the whole main marmara fault the partitioning in the cinarcik basin may produce magnitude 7 normal faulting earthquakes if their repetition time is about 250 years the 1896 earthquake may have been one of these normal fault earthquakes the marmara block is less than 1 ma prior to its formation it was part of the anatolian block at this time the ganos fault was already a dextral strike slip fault but the fault system in the sea of marmara would have been affected by an extensional component increasing toward the east that accounts for the increasing size of the sedimentary basins eastward

ground penetrating radar investigations along the north anatolian fault near izmit turkey constraints on the right lateral movement and slip history we analyze ground penetrating radar gpr profiles made across and parallel to the august 1999 earthquake ruptures of the north anatolian fault in turkey the profiles document cumulative right lateral offset of stream channels and the successive faulting of a medieval ottoman canal the dominance of fine sand to coarse gravel in the sections imaged allows for reasonably deep penetration and processed radar signals clearly image visible reflectors within the uppermost 5 m near kosekoy buried fluvial channel deposits exposed in some trenches dug to determine paleoseismicity are also visible on profiles and show a maximum 6 7 7 4 m of lateral displacement younger channel units display 4 5 4 9 m of right lateral displacement at 2 3 m depth and show that the penultimate rupture along the izmit segment produced a similar amount of displacement as in 1999 at the ottoman canal site gpr profiles complement a trench study and provide consistent results showing the occurrence of three faulting events after a d 1591 the date of canal construction this study demonstrates that the use of gpr method in paleoseismology contributes to better identification of cumulative slip along active faults

lithospheric elasticity promotes episodic fault activity based on the agreement between geodetic and geological plate velocities interplate fault slip rates are usually considered constant over long periods of time however measurements made at different time scales on intracontinental faults suggest that slip rate evolves with time we examine the slip evolution of a fault embedded in an elastic lithosphere loaded by plate motion we first assume that the fault friction varies due to a climatic cause then we show that high fault stress and low lithospheric stiffness favour large variations of slip rate in the case where fault weakening is controlled by slip rate we find that high loading velocity leads to a low stress constant slip rate while low loading velocity drives the fault slip rate to cycle between high and low values this suggests that paleoseismic slip rate could overpass the loading velocity but also fall to zero for some period of time

characteristics of the 1912 co seismic rupture along the north anatolian fault zone turkey implications for the expected marmara earthquake evidence of right lateral offsets associated with the 1912 earthquake mw 7 4 along the north anatolian fault gazikoy saros segment allow us to survey using dgps the co seismic and cumulative slip distribution the damage distribution and surface breaks related with the earthquake show an elongated zone of maximum intensity x msk parallel to the fault rupture on land but this may extend offshore to the north east and south west detailed mapping of the fault using topographic maps and aerial photographs indicates the existence of pull apart basins and pressure ridges at several localities the average 1912 offset along strike is 3 5 4 m and cumulative slip is 2 6 times that of individual movement the fault rupture geometry and slip distribution suggest the existence of three subsegments with a combined total length of 110 120 km a fault length and maximum slip similar to those of the 1999 izmit earthquake the amount of slip at the north easternmost section and in the coastal region of the sea of marmara reaches an average 4 m thereby implying the offshore exten sion of the 1912 rupture the results suggest that the 1912 event generated up to 150 km of surface faulting which would imply a mw 7 2 7 4 earthquake and which added with rupture lengths of the 1999 earthquakes help to constrain the remaining seismic gap in the sea of marmara

maximum earthquake magnitudes along different sections of the north anatolian fault zone abstract constraining the maximum likely magnitude of future earthquakes on continental transform faults has fundamental consequences for the expected seismic hazard since the recurrence time for those earthquakes is typically longer than a century such estimates rely primarily on well documented historical earthquake catalogs when available here we discuss the maximum observed earthquake magnitudes along different sections of the north anatolian fault zone nafz in relation to the age of the fault activity cumulative offset slip rate and maximum length of coherent fault segments the findings are based on a newly compiled catalog of historical earthquakes in the region using the extensive literary sources that exist owing to the long civilization record we find that the largest m7 8 8 0 earthquakes are exclusively observed along the older eastern part of the nafz that also has longer coherent fault segments in contrast the maximum observed events on the younger western part where the fault branches into two or more strands are smaller no first order relations between maximum magnitudes and fault offset or slip rates are found the results suggest that the maximum expected earthquake magnitude in the densely populated marmara istanbul region would probably not exceed m7 5 the findings are consistent with available knowledge for the san andreas fault and dead sea transform and can help in estimating hazard potential associated with different sections of large transform faults

spatio temporal behaviour of continental transform faults implications from the late quaternary slip history of the north anatolian fault turkey the slip history of the north anatolian fault naf is constrained by displacement and age data for the last 550 ka first i classified all available geological estimates as members of three group

a 48 kyr long slip rate history for the jordan valley segment of the dead sea fault abstract we investigate the late quaternary active deformation along the jordan valley segment of the left lateral dead sea fault and provide new insights on the behaviour of major continental faults the 110 km long fault segment shows systematic offsets of drainage systems surveyed at three sites along its southern section the isotopic dating of six paleoclimatic events yields a precise chronology for the onset of six generations of gully incisions at 47 5 ka bp 37 5 ka bp 13 ka bp 9 ka bp 7 ka bp and 5 ka bp additionally detailed mapping and reconstructions provide cumulative displacements for 20 dated incisions along the fault trace the individual amounts of cumulative slip consistently fall into six distinct classes this yields i an average constant slip rate of 4 7 to 5 1 mm yr for the last 47 5 kyr and ii a variable slip rate ranging from 3 5 mm yr to 11 mm yr over 2 kyr to 24 kyr long intervals taking into account that the last large earthquake occurred in ad 1033 we infer 3 5 to 5 m of present day slip deficit which corresponds to a mw 7 4 earthquake along the jordan valley fault segment the timing of cumulative offsets reveals slip rate variations critical to our understanding of the slip deficit and seismic cycle along major continental faults

westward propagation of the north anatolian fault into the northern aegean timing and kinematics we present new evidence for the propagation processes of the north anatolian fault folding in the dardanelles straits region allows us to document the timing of the deformation preceding and the finite displacement after the passage of the propagating tip of the fault the accuracy of the observations is due to interplay between deformation and the sea level changes in the mediterranean the well known messinian regression followed by the pliocene transgression the long term kinematics around the sea of marmara pull apart total displacement of about 85 km over the past 5 m y is similar to the present day kinematics deduced from space geodesy at a larger scale westward propagation of the north anatolian fault over nearly 2000 km in the past 10 m y appears to be associated with strain recovery suggesting that the continental lithosphere retains long term elasticity

steady late quaternary slip rate on the cinarcik section of the north anatolian fault near istanbul turkey the distribution of plate motion between multiple fault strands and how this distribution may evolve remain poorly understood despite the key implications for seismic hazards the north anatolian fault in northwest turkey is a prime example of a multistranded continental transform here we present the first constraints on late quaternary slip rates on its northern branch across the cinarcik basin in the eastern marmara sea we use both deep penetration and high resolution multichannel seismic reflection data with a stratigraphic age model to show that a depocenter has persisted near the fault bend responsible for that transform basin successively older depocenters have been transported westward by fault motion relative to eurasia indicating a uniform right lateral slip rate of 18 5 mm yr over the last 500 000 years compared to overall gps rates 23 24 mm yr thus the northern branch has slipped at a nearly constant rate and has accounted for most of the relative plate motion between eurasia and anatolia since 0 5 ma

saltwater intrusion and nitrate pollution in the coastal aquifer of dar es salaam tanzania dar es salaam quaternary coastal aquifer is a major source of water supply in dar es salaam city used for domestic agricultural and industrial uses however groundwater overdraft and contamination are the major problems affecting the aquifer system this study aims to define the principal hydrogeochemical processes controlling groundwater quality in the coastal strip of dar es salaam and to investigate whether the threats of seawater intrusion and pollution are influencing groundwater quality major cations and anions analysed in 134 groundwater samples reveal that groundwater is mainly affected by four factors dissolution of calcite and dolomite weathering of silicate minerals seawater intrusion due to aquifer overexploitation and nitrate pollution mainly caused by the use of pit latrines and septic tanks high enrichment of na and cl near the coast gives an indication of seawater intrusion into the aquifer as also supported from the na cl signature on the piper diagram the boreholes close to the coast have much higher na cl molar ratios than the boreholes located further inland the dissolution of calcite and dolomite in recharge areas results in ca hco3 and ca mg hco3 groundwater types further along flow paths ca2 and na ion exchange causes groundwater evolution to na hco3 type from the phreeqc simulation model it appears that groundwater is undersaturated to slightly oversaturated with respect to the calcite and dolomite minerals the results of this study provide important information required for the protection of the aquifer system

convectively driven turbulent mixing in the upper ocean abstract two experiments were performed to study the characteristics of turbulence in convective mixed layers in the upper ocean in the first a diurnal convective mixed layer developed in the bahamas under the influence of the cycle of daytime solar heating and nighttime evaporative cooling the mixed layer reached as deep as 100 m each night and restratified each day in the second the mixed layer of a warm core gulf stream ring deepened from less than 50 m to more than 150 m in a little more than a day when subjected to rapid cooling during a cold air outbreak although individual profiles of the rate of viscous dissipation of turbulent kinetic energy had considerable spatial and temporal variability the mean dissipation profiles were similar to those in convecting atmospheric boundary layers the is established by the surface buoyancy flux jb0 jb0 0 61 and 0 72 in the bahamas and ring data respectively compared with 0 64 in convecting atmospheric mixed layers the mean profiles decre

recent behavior of the north anatolian fault insights from an integrated paleoseismological data set 1 the north anatolian fault naf is a right lateral plate boundary fault that arcs across northern turkey for 1500 km almost the entire fault progressively ruptured in the 20th century its cascading style indicating that stress from one fault rupture triggers fault rupture of adjacent segments using published paleoseismic investigations this study integrates all of the existing information about the timing of paleoearthquakes on the naf paleoseismic investigation data are compiled into a database and for each site a bayesian ordering constrained age model is constructed in a consistent framework spatial variability of recurrence intervals suggests a spatial pattern in the behavior of earthquakes on the naf that may correspond to the tectonic provinces within the anatolian plate in the west the shear stress associated with the escaping anatolian plate interplays with the tensile stress associated with the aegean extensional province along this western transtensional section we recognize short recurrence intervals and switching between the furcated fault strands the central section of the naf is translational with little influence of fault normal stresses from other tectonic sources this section tends to rupture in unison or close succession the eastern section of the naf is transpressional due to the compressional fault normal stress associated with the indenting arabian plate along this section the recurrence intervals are bimodal which we attribute to variable normal stress although there are other possible causes

m 7 earthquake rupture forecast and time dependent probability for the sea of marmara region turkey we forecast time independent and time dependent earthquake ruptures in the marmara region of turkey for the next 30 years using a new fault segmentation model we also augment time dependent brownian passage time bpt probability with static coulomb stress changes cff from interacting faults we calculate mw 6 5 probability from 26 individual fault sources in the marmara region we also consider a multisegment rupture model that allows higher magnitude ruptures over some segments of the northern branch of the north anatolian fault zone beneath the marmara sea a total of 10 different mw 7 0 to mw 8 0 multisegment ruptures are combined with the other regional faults at rates that balance the overall moment accumulation we use gaussian random distributions to treat parameter uncertainties e g aperiodicity maximum expected magnitude slip rate and consequently mean recurrence time of the statistical distributions associated with each fault source we then estimate uncertainties of the 30 year probability values for the next characteristic event obtained from three different models poisson bpt and bpt cff using a monte carlo procedure the gerede fault segment located at the eastern end of the marmara region shows the highest 30 year probability with a poisson value of 29 and a time dependent interaction probability of 48 we find an aggregated 30 year poisson probability of m 7 3 earthquakes at istanbul of 35 which increases to 47 if time dependence and stress transfer are considered we calculate a twofold probability gain ratio time dependent to time independent on the southern strands of the north anatolian fault zone

paleoseismic evidence of characteristic slip on the western segment of the north anatolian fault turkey we have conducted a paleoseismic investigation of serial fault rupture at one site along the 110 km rupture of the north anatolian fault that produced the mw 7 4 earthquake of 17 august 1999 the benefit of using a recent rupture to compare serial ruptures lies in the fact that the location magnitude and slip vector of the most recent event are all very well documented we wished to determine whether or not the previous few ruptures of the fault were similar to the recent one we chose a site at a step over between two major strike slip traces where the principal fault is a normal fault our two excavations across the 1999 rupture reveal fluvial sands and gravels with two colluvial wedges related to previous earthquakes each wedge is about 0 8 m thick considering the processes of collapse and subsequent diffusion that are responsible for the formation of a colluvial wedge we suggest that the two paleoscarps were similar in height to the 1999 scarp this similarity supports the concept of characteristic slip at least for this location along the fault accelerator mass spectrometry ams radiocarbon dates of 16 charcoal samples are consistent with the interpretation that these two paleoscarps formed during large historical events in 1509 and 1719 if this is correct the most recent three ruptures at the site have occurred at 210 and 280 year intervals

surface rupture and slip distribution of the 12 november 1999 duzce earthquake m 7 1 north anatolian fault bolu turkey the 12 november 1999 earthquake m 7 1 occurred on the duzce fault a splay of the north anatolian fault in the bolu basin approximately three months after the 17 august 1999 m 7 4 earthquake the surface rupture was 40 km long and the maximum right lateral offset was 500 5 cm averaging 300 cm the 9 km of the westernmost part of the rupture along the southern margin of the eften lake had a 350 cm maximum vertical displacement normal faulting some of which was already ruptured during the 17 august 1999 event with few tens of centimeters the surface rupture has a generally simple narrow deformation zone of 0 5 5 m however in some places it widens to 50 m transtensional and transpressional structures were observed within releasing and restraining step over areas respectively the larger dextral offsets on some streams indicate previous events the dextral slip measurements along the rupture reflect a symmetric distribution the eastern connection of this rupture zone with the main trace of north anatolian fault remains unclear because the bakacak and elmalik fault which are connecting faults had no surface rupture manuscript received 14 november 2000

mixing in a coastal environment 1 a view from dye dispersion 1 dye release experiments were performed together with microstructure profiling to compare the two methods of estimating diapycnal diffusivity during summer and fall stratification on the continental shelf south of new england the experiments were done in 1996 and 1997 as part of the coastal mixing and optics experiment during the 100 hours or so of the experiments the area of the dye patches grew from less than 1 km2 to more than 50 km2 sundermeyer and ledwell 2001 diapycnal diffusivities inferred from dye dispersion range from 10 6 to 10 5 m2 s at buoyancy frequencies from 9 to 28 cycles hour diffusivities estimated from the dye and those estimated from dissipation rates in the companion paper by oakey and greenan 2004 agree closely in most cases estimates of diffusivities from towed conductivity microstructure measurements made during the cruises by duda and rehmann 2002 and rehmann and duda 2000 are fairly consistent with the dye diffusivities the dye diffusivities would be predicted well by an empirical formula involving shear and stratification statistics developed by mackinnon and gregg 2003 from profiling microstructure measurements obtained at the same site in august 1996 all of the measurements support the general conclusion that the diffusivity averaged over several days is seldom greater than 10 5 m2 s in the stratified waters at the site and usually not much greater than 10 6 m2 s severe storms such as a hurricane that passed over the cmo site in 1996 can dramatically increase the mixing at the site however

radioelements radiogenic helium and age relationships for groundwaters from the granites at stripa sweden abstract the solution of radioelements and radiogenic 4he by groundwaters in fractured rocks is dependent upon the radioelement distribution in the rock matrix and the extent of the rock water interface the 234 u 238 u activity ratio and the dissolved u rn and he contents of such groundwaters respond to changes in the flow regime with time although 234 u 238 u activity ratios change with groundwater residence time as a consequence of 234th recoil induced solution of 234u the activity ratio is strongly influenced by the u distribution within fractures by the extent of the rock water interface and by the amount of 238u in solution a model for the quantitative evaluation of these effects is presented groundwaters from depths up to 880 m in the stripa granite have variable dissolved uranium contents and 234 u 238 u activity ratios the uranium geochemistry is primarily determined by variations in flow path rather than by groundwater age dissolved radiogenic 4he in the groundwaters increases with their depth of origin and is dependent upon the u content of the granite and upon its fracture porosity it increases with groundwater residence time but movement of 4he by diffusion and transport processes make the actual groundwater age indeterminate

paleoseismological evidence of recent earthquakes on the 1967 mudurnu valley earthquake segment of the north anatolian fault zone this study contributes paleoseismological data on the recent history of surface rupturing earthquakes on the southern main branch of the north anatolian fault zone nafz turkey west of the bolu basin we focused on the fault segment that ruptured during the 1967 mudurnu valley earthquake m s 7 1 which preceded the devastating earthquakes of 1999 in the sequence of westward migrating nafz earthquakes since 1939 geomorphological mapping was carried out in a search for trenching sites on the central part of the 22 july 1967 earthquake segment in the absence of locations in sedimentary environments best suited for paleoseismological interpretation of faulted holocene deposits we trenched fluvial channel deposits at a terrace of the gravel dominated mudurnu river the most conservative interpretation of the trench stratigraphy and faulting evidence suggests that at least one paleoearthquake most probably two occurred after a d 1693 the 1967 earthquake segment has ruptured at least once since the historical earthquake of a d 1668 which was previously considered to be a likely candidate for the penultimate event and before 1967 it is not possible to confidently assign the penultimate event to one of the post a d 1693 historical earthquakes in the broader area around the mudurnu valley e g the earthquake of a d 1719 because the historical data published so far do not provide conclusive information about when past ruptures of the mudurnu valley branch of the nafz a secluded area did or did not take place

extension of the north anatolian fault into the north aegean trough evidence for transtension strain partitioning and analogues for sea of marmara basin models 1 the north aegean trough is tectonically controlled by the projection of the north anatolian fault from western turkey and the sea of marmara into the aegean where deformation is distributed in contrast to the simple strike slip fault model for central eastern turkey this region accommodates extensional and dextral displacement new side scan sonar data coupled with new subbottom profiler and published seismic data reveal evidence for dextral displacement within the eastern trough and gulf of saros in the form of oblique en echelon and riedel r r and p fractures and displaced geomorphic features strain partitioning in the shallow crust allows the following two styles of faulting to coexist supported by earthquake focal mechanisms 1 transtensional basin bounding faults controlling the significant vertical topography of the basin and 2 dextral faulting within the central basin these styles of faulting merge at greater depths into a single fault a possible sinistral nw striking fault separates two subbasins and may indicate crustal block rotation with deformation focused in block corners such evidence and models from the north aegean are similar to models of transtension and pull apart basins within the sea of marmara

a palaeoclimatic record from the ledo paniselian aquifer in belgium indications for groundwater recharge and flow in a periglacial environment abstract understanding the mechanisms of groundwater recharge and flow in periglacial environments remains enigmatic methane releases from melting permafrost in a warming world are a hot topic in contemporary climate research noble gas analyses have been proposed to study methane driven degassing in lakes as well as in permafrost terrains the ledo paniselian aquifer is shown to provide an analogue for such processes from the last period of global warming after the lgm it is postulated that recharge from methane bubbling thermokarst lakes to groundwater took place and can be recognized by a specific signature in the groundwater the ledo paniselian aquifer offers unique opportunities to study periglacial groundwater recharge during the lgm as it was located in the permanent permafrost area to the south of the ice sheet at that time it contains holocene and pleistocene groundwaters which are separated by a recharge gap referring to permafrost during the lgm this is confirmed by noble gas temperature ngt data in the samples immediately upstream of this gap several potential indicators for the specific methanogenic recharge conditions from thawing permafrost are being put forward based on noble gases chemical and isotopic data immediately upstream of the age gap groundwaters show strikingly deviating hco3 so42 13c 18o and 2h compared to the regional trend while their 14c model ages are too young and ngts seem too high these samples are affected by degassing which is not an artefact of sampling and which according to their radiogenic helium concentrations occurred early on during recharge or shortly thereafter the origin of these samples could be explained by the conditions prevailing as the permafrost thawed and groundwater recharge could resume it is inferred that the degassed samples were infiltrated during or shortly after the lgm when recharge from methane bubbling thermokarst lakes to groundwater took place associated to the melting permafrost

geological slip rates along the north anatolian fault in the marmara region 1 reliable piercing points on both sides of the sea of marmara enabled us to obtain an estimate of the slip rate over time scales of 10 15 ka on different fault strands of the north anatolian fault naf system we analyzed geomorphic features in the gulfs of izmit gemlik sea of marmara and saros ne aegean sea which were passively displaced by the naf strands after their abandonment related to the post glacial sea level rise results for the main northern strand consistently similar on both sides of the marmara pull apart are in the order of 10 mm yr about one half of that expected from geodetic measurements and accepted plate tectonic models in the southern branch of the naf the estimated rate of 4 mm yr is only slightly higher than that given by geodetic models our findings have implications for both neo tectonic reconstructions of the submerged portion of the naf system and fault interactions and seismic hazard estimates in the marmara region they suggest that either the total anatolia eurasia plate motion is more diffuse than previously reported or geodetic data are not representative of the geological time scale deformations moreover they suggest that a significant amount of stress is accommodated along the southern strand of the naf system on which the last large m 7 earthquakes dates back to 1419 1855 and 1863 ad

dating of glacial palaeogroundwater in the ordovician cambrian aquifer system northern baltic artesian basin abstract the ordovician cambrian aquifer system in the northern baltic artesian basin contains glacial palaeogroundwater that originates from the scandinavian ice sheet that covered the study area in the pleistocene previously no absolute dating of this palaeogroundwater has been attempted in this multi tracer study we use 3h 14c 4he and stable isotopes of water to constrain the age distribution of groundwater we apply the geochemical modelling approach developed by van der kemp et al 2000 and blaser et al 2010 to calculate the theoretical composition of recharge waters in three hypothetical conditions modern glacial and interstadial for 14c model age calculations in the second phase of the geochemical modelling the calculated recharge water compositions are used to calculate the 14c model ages using a series of inverse models developed with netpath the calculated 14c model ages show that the groundwater in the aquifer system originates from three different climatic periods 1 the post glacial period 2 the late glacial maximum lgm and 3 the pre lgm period a larger pre lgm component seems to be present in the southern and north eastern parts of the aquifer system where the radiogenic 4he concentrations are higher from 3 0 10 5 to 5 5 10 4 cc g 1 and the stable isotopic composition of water is heavier 18o from 13 5 to 17 3 glacial palaeogroundwater from the north western part of the aquifer system is younger and has 14c model ages that coincide with the end of the lgm period it is also characterized by lower radiogenic 4he concentrations 2 0 10 5 cc g 1 and lighter stable isotopic composition 18o from 17 7 to 22 4 relations between radiogenic 4he and 14c model ages and between radiogenic 4he and cl concentration show that groundwater in the aquifer system does not have a single well defined age rather the groundwater age distribution has been influenced by mixing between waters originating from end members with strongly differing ages overall the results suggest that in the shallower northern part of the aquifer system significant changes in groundwater composition can be brought about by glacial meltwater intrusion during a single glaciation however multiple cycles of glacial advance and retreat are needed to transport glacial meltwater to the deeper parts of the aquifer system

stable isotopes carbon 14 and hydrochemical composition from a basaltic aquifer in sao paulo state brazil the cretaceous serra geral aquifer sga is contained within one of the largest continental flood basalts in the world reaching a thickness up to 1700 m in the center of the parana basin the sga is one of the most important groundwater reservoirs in northeastern sao paulo state brazil responsible for water supply to cities and agriculture in order to evaluate the geochemical and isotopic evolution of sga as well as to determine the mean residence time a groundwater sampling campaign was carried out over the sga in sao paulo state brazil from january to april 2013 two main hydrochemical facies were recognized ca mg hco3 related to water rock interaction reactions in basaltic outcrop such as mineral dissolution due to atmospheric co2 uptake and alkaline na hco3 groundwater evolved from mixing with groundwater from the underlying guarani aquifer system stable isotope 18o and 2h ratios range from 8 87 to 5 32 vsmow and 61 31 to 31 64 vsmow respectively closely following the gmwl spatial and temporal variations in isotope ratios are associated with the south atlantic convergence zone activities and the type of rain responsible for recharge values for 13c vary from 21 53 to 7 11 vpdb while 14c activities vary from 1 2 pcm to more than 100 pcm presenting a trend to enrichment and decrease in 14c activities westward concordant with the regional groundwater flow direction most recent groundwaters have 13c ratio contents mostly consistent with c3 plants

kinematics and evolution of the northern branch of the north anatolian fault ganos fault between the sea of marmara and the gulf of saros abstract the wsw ene trending ganos fault is a dextral strike slip fault running parallel to and southwest of the west marmara trough and south of the saros trough dextral structures started evolving in the early miocene and at this time the ganos fault system developed from a part of the thrace eskisehir fault system beginning in the late pliocene 3 5 ma the north anatolian transform fault propagated into the marmara region and captured the ganos fault subsequently this fault has accommodated the westward movement of the anatolian block because of the curvature of the microplate boundary in this area the ganos fault system has tended to rotate counterclockwise farther west in the gulf of saros the strike slip motion was accommodated by a new fault on the northern margin of the gulf rather than along the northern coast of the gelibolu peninsula as previously thought this interpretation differs from previous assessments of the position of the northern strand of the north anatolian fault marmara segment in the marmara sea and in the gulf of saros the role of the ganos fault proposed in this paper is considerably different from that proposed by earlier studies while the revised orientation of the north anatolian fault on land is about 7 different than specified by previous authors at sea it is different by 32 counterclockwise and 23 clockwise in the west marmara and saros submarine depressions respectively the revised position of the ganos fault in the marmara sea derived from shallow and conventional seismic reflection data calls into question the validity of evolutionary models previously used in kinematic and stress failure analyses in particular it is not possible to regard the marmara sea as a pull apart basin and the gulf of saros as a transtensional half graben furthermore palinspastic maps taking into account the revised position of the ganos fault and gps slip vectors support the idea that a dextral master fault is present to the north of the saros trough with a sinistral oblique fault dominated by normal offset gelibolu fault to its south the gelibolu fault is reactivated in a limited region

fault behavior and characteristic earthquakes examples from the wasatch and san andreas fault zones paleoseismological data for the wasatch and san andreas fault zones have led to the formulation of the characteristic earthquake model which postulates that individual faults and fault segments tend to generate essentially same size or characteristic earthquakes having a relatively narrow range of magnitudes near the maximum analysis of scarp derived colluvium in trench exposures across the wasatch fault provides estimates of the timing and displacement associated with individual surface faulting earthquakes at all of the sites studied the displacement per event has been consistently large measured values range from 1 6 to 2 6 m and the average is about 2 m on the basis of variability in the timing of individual events as well as changes in scarp morphology and fault geometry six major segments are recognized along the wasatch fault on the basis of the most likely number of surface faulting events 18 that have occurred on segments of the wasatch fault zone during the past 8000 years an average recurrence interval of 400 666 years with a preferred average of 444 years is calculated for the entire zone geologic data on the distribution of slip associated with prehistoric earthquakes and slip rates along the south central segment of the san andreas fault suggest that the m 8 1857 earthquake is a characteristic earthquake for this segment comparisons of earthquake recurrence relationships on both the wasatch and san andreas faults based on historical seismicity data and geologic data show that a linear constant b value extrapolation of the cumulative recurrence curve from the smaller magnitudes leads to gross underestimates of the frequency of occurrence of the large or characteristic earthquakes only by assuming a low b value in the moderate magnitude range can the seismicity data on small earthquakes be reconciled with geologic data on large earthquakes the characteristic earthquake appears to be a fundamental aspect of the behavior of the wasatch and san andreas faults and may apply to many other faults as well

revision of fontes garnier s model for the initial 14c content of dissolved inorganic carbon used in groundwater dating abstract the widely applied model for groundwater dating using 14c proposed by fontes and garnier fg or 2 using different fractionation factors if the exchange process is dominated by soil co2 gas as opposed to solid carbonate mineral typically calcite an analysis of the fg however 14c0 will be slightly underestimated finally in carbonate systems undergoing complex geochemical reactions such as oxidation of organic carbon radiocarbon ages are best estimated by inverse geochemical modeling techniques

a comparison of geodetic and geologic rates prior to large strike slip earthquakes a diversity of earthquake cycle behaviors comparison of preevent geodetic and geologic rates in three large magnitude mw 7 6 7 9 strike slip earthquakes reveals a wide range of behaviors specifically geodetic rates of 26 28 mm yr for the north anatolian fault along the 1999 mw 7 6 izmit rupture are 40 faster than holocene geologic rates in contrast geodetic rates of 6 8 mm yr along the denali fault prior to the 2002 mw 7 9 denali earthquake are only approximately half as fast as the latest pleistocene holocene geologic rate of 12 mm yr in the third example where a sufficiently long pre earthquake geodetic time series exists the geodetic and geologic rates along the 2001 mw 7 8 kokoxili rupture on the kunlun fault are approximately equal at 11 mm yr these results are not readily explicable with extant earthquake cycle modeling suggesting that they may instead be due to some combination of regional kinematic fault interactions temporal variations in the strength of lithospheric scale shear zones and or variations in local relative plate motion rate whatever the exact causes of these variable behaviors these observations indicate that either the ratio of geodetic to geologic rates before an earthquake may not be diagnostic of the time to the next earthquake as predicted by many rheologically based geodynamic models of earthquake cycle behavior or different behaviors characterize different fault systems in a manner that is not yet understood or predictable

near surface horizontal convergence and dispersion near the tidal mixing front on northeastern georges bank abstract horizontal dispersion and convergence are evaluated from near surface drifter data collected during the summer and autumn of 1988 and summer of 1989 in the vicinity of the tidal mixing front on northeastern georges bank the effective horizontal diffusivity coefficient k e estimated from the relative motion of the drifters over the duration of the cluster tracking increases as the cluster length scale with a range from approximately 100 to 450 m 2 s 1 for length scales of approximately 5 to 58 km at length scales k e is near zero with many negative estimates indicative of convergence at length scales 20 km k e increases in magnitude and scatter above 30 km length scales k e is typically between 200 400 m 2 s 1 the dispersion as a function of length scale is compared to published estimates using apparent diffusivities which are adjusted for the finite size of the drifter cluster at release georges bank shows lower apparent diffusivities at length scales 20 km the latter are believed to be principally due to the large horizontal gradients in the seasonal flow field although other processes perhaps associated with the large tidal currents may also contribute at the shorter length scales the low dispersion is due to convergent processes examples of convergence at different locations and under different wind and stratification conditions are presented convergence near the tidal mixing front tends to occur under light wind conditions and was observed in both seasons and in both years during two intense southwestward windstorms drifters also converged in the bank s vertically well mixed zone apparently due to a combination of spatially varying ekman depth and topographic effects

global positioning system constraints on plate kinematics and dynamics in the eastern mediterranean and caucasus we present and interpret global positioning system gps measurements of crustal motions for the period 1988 1997 at 189 sites extending east west from the caucasus mountains to the adriatic sea and north south from the southern edge of the eurasian plate to the northern edge of the african plate sites on the northern arabian platform move 18 2 mm yr at n25 5 w relative to eurasia less than the nuvel 1a circuit closure rate 25 1 mm yr at n21 7 w preliminary motion estimates 1994 1997 for stations located in egypt on the northeastern part of africa show northward motion at 5 6 2 mm yr also slower than nuvel ia estimates 10 1 mm yr at n2 4 e eastern turkey is characterized by distributed deformation while central turkey is characterized by coherent plate motion internal deformation of 2 mm yr involving westward displacement and counterclockwise rotation of the anatolian plate the anatolian plate is de coupled from eurasia along the right lateral strike slip north anatolian fault naf we derive a best fitting euler vector for anatolia eurasia motion of 30 7 0 8 n 32 6 0 4 e 1 2 0 1 myr the euler vector gives an upper bound for naf slip rate of 24 1 mm yr we determine a preliminary gps arabia anatolia euler vector of 32 9 1 2 n 40 3 1 1 e 0 8 0 2 myr and an upper bound on left lateral slip on the east anatolian fault eaf of 9 1 mm yr the central and southern aegean is characterized by coherent motion internal deformation of 2 mm yr toward the sw at 30 1 mm yr relative to eurasia stations in the se aegean deviate significantly from the overall motion of the southern aegean showing increasing velocities toward the trench and reaching 10 1 mm yr relative to the southern aegean as a whole

estimating 14c groundwater ages in a methanogenic aquifer this paper addresses the problem of 14c age dating of groundwaters in a confined regional aquifer affected by methanogenesis increasing ch4 concentrations along the groundwater flow system and 13c and 14c isotopic data for dissolved inorganic carbon dissolved organic carbon and ch4 clearly show the effect of methanogenesis on groundwater chemistry inverse reaction path modeling using netpath indicates the predominant geochemical reactions controlling the chemical evolution of groundwater in the aquifer are incongruent dissolution of dolomite ion exchange methanogenesis and oxidation of sedimentary organic matter modeling of groundwater 14c ages using netpath indicates that a significant part of groundwater in the alliston aquifer is less than 13 000 years old however older groundwater in the range of 15 000 23 000 years is also present in the aquifer this paper demonstrates that 14c ages calculated using netpath incorporating the effects of methanogenesis on the carbon pools provide reasonable groundwater ages that were not possible by other isotopic methods

slip history of the 1944 bolu gerede earthquake rupture along the north anatolian fault system implications for recurrence behavior of multisegment earthquakes 1 recent research shows that active fault systems produce multisegment earthquakes however we have yet to understand the faulting behavior of various spatial patterns of segments we conducted a three dimensional trenching survey to reconstruct the detailed slip history of a fault segment that ruptured as one of the multisegment ruptures along the north anatolian fault system the trench site on the gerede segment recorded a maximum right lateral slip of up to 6 m that was associated with the 1944 bolu gerede earthquake m 7 4 fault exposures show evidence of four paleoearthquakes radiocarbon dates a refined probability density distribution and correlation with historical earthquakes place the mean repeat time at 330 years four discrete paleoslips yield a slip per event of 5 0 0 8 m with a coefficient of variation of 0 2 our research suggests that multisegment earthquakes exhibit various spatial patterns regardless of recurrence with quasiperiodicity and characteristic slip coincidentally the fault geometry exhibits extremely linear traces suggesting simple stress accumulation and release through earthquake cycles furthermore the 1944 event did not occur in a single segment and the gerede segment probably ruptured within a slip pulse like rupture during a multisegment earthquake a comparable geological slip rate of 17 mm a 1 based on a gps based strain rate supports the persistence of macroscopic asperity through recent geological time therefore we conclude that a segment with simple fault geometry along a strike slip fault system plays an important role in forecasting the timing of future multisegment earthquakes but the spatial extent of such earthquakes needs to be explored further

14c age reassessment of groundwater from the discharge zone due to cross flow mixing in the deep confined aquifer abstract in a groundwater flow system the age of groundwater should gradually increase from the recharge zone to the discharge zone within the same streamline however it is occasionally observed that the groundwater age becomes younger in the discharge zone in the piedmont alluvial plain and the oldest age often appears in the middle of the plain a new set of groundwater chemistry and isotopes was employed to reassess the groundwater 14c ages from the discharge zone in the north china plain ncp carbonate precipitation organic matter oxidation and cross flow mixing in the groundwater from the recharge zone to the discharge zone are recognized according to the corresponding changes of hco3 or dic and 13c in the same streamline of the third aquifer of the ncp the effects of carbonate precipitation and organic matter oxidation are calibrated with a 13c mixing model and dic correction but these corrected 14c ages seem unreasonable because they grow younger from the middle plain to the discharge zone in the ncp the relationship of cl content and the recharge distance is used to estimate the expected cl content in the discharge zone and ln a14c cl is proposed to correct the a14c in groundwater for the effect of cross flow mixing the 14c ages were reassessed with the corrected a14c due to the cross flow mixing varying from 1 25 to 30 58 ka and the groundwater becomes older gradually from the recharge zone to the discharge zone the results suggest that the reassessed 14c ages are more reasonable for the groundwater from the discharge zone due to cross flow mixing

the seismic activity of the marmara sea region over the last 2000 years we examined the seismicity of the region of the sea of marmara in northwest turkey over the last 2000 yr using the historical record of the region we found no evidence for truly large earthquakes of a size comparable to those in the north anatolian fault zone in the marmara basin events are smaller in keeping with the known fault segmentation of the basin over the last 2000 yr seismic mo ment release accounted for the known right lateral shear velocity across the marmara region observed by global positioning system measurements its average rate is relatively constant and varies between 1 6 and 2 4 cm yr the long term seismicity in the marmara sea region shows that large earthquakes are less frequent than pre dicted from the 100 yr long instrumental period

strike slip fault geometry in turkey and its influence on earthquake activity the geometry of turkish strike slip faults has been reviewed and described from this data set it appears that fault geometry the distribution of discontinuities such as bends and stepovers along the main fault trace plays an important role in controlling the location of large earthquake rupture segments along the fault zones large earthquake ruptures generally do not propagate past individual stepovers that are wider than 5 km or bends that have angles greater than about 30 more important than the size of each discontinuity however is the total geometric pattern i e the distribution of adjacent bends and stepovers based not only on distance from one another but also on relative discontinuity size certain geometric patterns restraining single or double bends are particularly common and can be viewed as responsible for strain accumulation along portions of the fault zone fault geometry not only plays a role in the extent of earthquake rupture but also in characteristics of earthquake behavior for example large earthquake epicenters often occur near restraining bends or double bends furthermore aftershocks and swarm activity can often be associated with releasing areas areas along the strike slip fault that are undergoing a relatively large amount of extension

the recharge of glacial meltwater and its influence on the geochemical evolution of groundwater in the ordovician cambrian aquifer system northern part of the baltic artesian basin abstract the geochemical evolution of groundwater in the ordovician cambrian aquifer system in the northern part of the baltic artesian basin bab illustrates how continental glaciations have influenced groundwater systems in proglacial areas the aquifer system contains water that has originated from various end members recent meteoric water glacial meltwater and relict na cl brine the saline formation water that occupied the aquifer system prior to the glacial meltwater intrusion has been diluted by meltwaters of advancing retreating ice sheets the diversity in the origin of groundwater in the aquifer system is illustrated by a wide variety in 18 o values that range from 11 to 22 5 these values are mostly depleted with respect to values found in modern precipitation in the area the chemical and isotopic composition of groundwater has been influenced by mixing between waters originating from different end members in addition the freshening of a previously saline water aquifer due to glacial meltwater intrusion has initiated various types of water rock interaction e g ion exchange carbonate mineral dissolution

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

submarine earthquake history of the cinarcik segment of the north anatolian fault in the marmara sea turkey the north anatolian fault naf in the marmara sea is a significant hazard for the city of istanbul the use of paleoseismological data to provide an accurate seismic risk assessment for the area is constrained by the fact that the naf system is submarine thus a history of paleoearthquakes can be inferred only by using marine sediment cores here a record of turbidites was obtained in two cores and used to reconstruct the earthquake history along the cinarcik segment a main branch of the naf klg04 was collected from a berm north of the fault and klg03 was positioned in the cinarcik basin south of the fault the cores were correlated using long term geo chemical variations in the sediment and turbidites deposited simultaneously at both sites were then identified radionuclide measurements suggest the most recent turbi dite was triggered by the 1894 c e m w 7 3 earthquake we conclude that the turbidites identified at both sites are earthquake generated based on their particular sedimento logical and geochemical signatures the correlation of turbidites at berm and basin sites and the match of the most recent turbidite with a nineteenth century historical earthquake to date older turbidites we used carbon 14 and paleomagnetic data to build an oxcal model with a local reservoir correction of 400 50 yr the cinarcik segment is found to have ruptured in 1509 c e sometime in the fourteenth century in 989 c e and in 740 c e with a mean recurrence interval in the range of 256 321 years finally we used the earthquake record obtained to review the rupture history of the adjacent segments over the past 1500 years