the thermal and mineral springs of aitoloakarnania prefecture function mechanism and origin of groundwater the study area is located in the northwestern part of greece in aitoloakarnania prefecture in this region where no volcanic activity exists thermal springs such as kremasta and kokkino stefani well known for their healing properties occur the objective of this study was the investigation of these springs as well as the study of the chemical composition and origin of water relationships between these springs were also examined the geological setting of the area comprises sedimentary rocks of the pindos gavrovo tripolis and ionian geotectonic zones deformed by orogenic movements followed by neogene extensional tectonism the thermal and mineral springs were classified into three main groups the first group is characterized by ca hco3 water type and low water temperatures it corresponds to the springs that are hosted in the ionian zone and their possible enrichment in so4 is mainly attributed to the evaporites the other two groups consist of alkaline thermal water mainly hosted in the formations of gavrovo tripolis zone in these two groups the very strong reducing conditions that prevail are expressed by high amounts of nh3 and h2s moreover na f li sr and ba display elevated concentrations the second includes mineral waters of ca na hco3 type that are depleted in calcium their residence time is rather long and they originate from deep water circulation through siliceous rocks the third group includes thermal waters of ca mg na hco3 water type of higher water temperatures that reveal characteristics of deep circulation directly associated with the underlain limestones

geochemistry genesis and health implications of fluoriferous groundwaters in the upper regions of ghana the most appropriate and widely used source of drinking water for the populations of the upper regions of ghana is groundwater in general groundwater quality is acceptable except for some parts of the bolgatanga and bongo districts where there are occurrences of elevated levels of natural groundwater fluoride concentrations of groundwater fluoride in excess of the world health organization who maximum guideline value 1 5 mg l in the bongo area have been known since 1978 however the effect of fluoride on people ingesting the water did not receive public and medical attention until october 1993 when health personnel were asked to investigate the cause of stained teeth in school children the investigation established that 62 of the total population of school children in the bongo area had dental fluorosis against this background a study was initiated to understand the geochemistry genesis and distribution of fluoride in relation to the geology of the area groundwater fluoride in the upper regions ranges from 0 11 to 4 60 ppm with the highest concentrations associated with the fluorine enriched bongo coarse grained hornblende granite and syenite suite the source of groundwater fluoride within the bongo granitoids is dissolution of the mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products applying the who recommended guideline values for fluoride in drinking water reveals that 49 of wells in the area deliver water below the optimum level of 0 5 mg l f these populations are thus prone to dental caries twenty eight percent of the wells fall within the optimum interval for good dental health 0 5 1 5 mg l f twenty three percent of the wells have concentrations above the recommended maximum guideline limit of 1 5 mg l f this population is susceptible to dental and possibly skeletal fluorosis climatic conditions of the area suggest that the individual water consumption is in the order of 3 to 4 l which is higher than the who estimate of 2 l adult day in addition dietary intake for the upper region population is probably higher than who baseline values 0 2 0 5 mg day this implies that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected geochemical symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education programs in the region by casting fluoride data into contoured geochemical health risk maps using intake interval guidelines more closely aligned to regional climatic and dietary conditions health officals can better judge the impacts regional and population based of fluoride on segments of the population such as various sex and age groups

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

the origin of fluoride in groundwater supply to hermosillo city sonora mexico anomalous high fluoride concentration up to 7 59 mg dm3 is found in groundwater from la victoria area this water is used to supply drinking water to hermosillo city sonora geochemistry of groundwater relationship between physicochemical parameters hydrogeology and geologic setting were correlated to define the origin and the geochemical mechanisms of groundwater fluorine enrichment high fluoride concentration is associated with high bicarbonates ph and temperature and it decreases toward the west and south of the area fluoride is in negative correlation to calcium concentration sodium sulphate facies of regional deep water flow are related to high fluoride concentration high electric resistivity rocks associated with granites from the sierra bachoco basement might be the deep source of fluoride outcropping of sierra bachoco in the west causes upward regional flow groundwater of longer residence time can be pumped there the anomalous area is restricted to la victoria because calcareous paleozoic rocks outcrop to the south

centroid moment tensor solutions for july september 1998 abstract centroid moment tensor solutions are presented for 214 earthquakes that occurred during the third quarter of 1998 the solutions are obtained using corrections for aspherical earth structure represented by a whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward dziewonski a m woodward r l 1992 acoustic imaging at the planetary scale in emert h harjes h p eds acoustical imaging plenum new york 19 785 797 a new model of anelastic attenuation of durek and ekstrom durek j j ekstrom g 1996 a radial model of anelasticity consistent with long period surface wave attenuation bull seism soc am 86 144 158 is used to predict the decay of the waveforms

the characteristic time scale for basin hydrological response using radar data abstract the transformation of rainfall into runoff at a basin outlet is the combined effect of many hydrological processes which occur at a wide range of spatial and temporal scales however determining the scale of the combined hydrological response of the basin is still problematic and concepts for its definition are yet to be identified in this paper high resolution meteorological radar data are used for the determination of a characteristic temporal scale for the hydrological response of the basin the response time scale t s t s is defined as the time scale at which the pattern of the time averaged radar rainfall hietograph is most similar to the pattern of the measured outlet runoff hydrograph the existence of such similarity at a relatively stable time scale for a specific basin indicates that it is an intrinsic property of the basin and is related to its hydrological response the identification of the response time scale is carried out by analysis of observations only without assuming a specific rainfall runoff model t s is examined in four small basins 10 100 km 2 in israel the spatial scale is assumed as the entire basin for all analyzed basins a stable response time scale is identified relatively short time scales are found for the urban and arid basins 15 30 min while for the rural basins longer time scale are identified 90 180 min the issues of relationship between the response time scale and basin properties and modeling at the response time scale have yet to be determined

imaging lateral heterogeneity in the northern apennines from time reversal of reflected surface waves summary prominent arrivals in the coda of seismograms from the wider alpine area can be associated with lateral reflections of love waves at the northern apennines mountain chain italy where structural heterogeneity causes an abrupt contrast in phase velocity we discuss an approach to image lateral heterogeneity from reflected surface waves using intermediate period threecomponent coda waveforms as sources for an adjoint wavefield that propagates the reflections backward in time we numerically compute three dimensional sensitivity kernels for the dependence of coda waveforms on p velocity s velocity and density based upon correlations between the adjoint and the regular forward wavefields we consider synthetic coda waveforms for a simplified model of the northern apennines as well as real coda observations from five moderate magnitude earthquakes m w 4 6 5 6 in the southern alps wave propagation is simulated using the spectral element method for which a 3 d regional earth model is used in the case of real data single and combined event sensitivity kernels provide clear images of the reflectivity associated with the northern apennines in kernels for density and s wave speed the kernels show that surface wave reflections occur near the axial zone of the mountain chain apart from the apennines the approach is able to image other smaller reflectivity patches from the coda waveforms like the ivrea zone in the southern alps our coda misfit kernels can be integrated in a gradient based waveform tomography where they could enhance the sharpness of the model at lateral discontinuities

cenozoic extension in coastal dhofar southern oman implications on the oblique rifting of the gulf of aden a detailed analysis of fault populations that affect the paleocene to early miocene sedimentary succession of southern dhofar allows the definition of a time sequence of paleostresses and the reconstruction of the rifting history of the eastern gulf of aden two distinct phases of n20j and n160j trending extensions took place during the deposition of the synrift dhofar group from late priabonian 35 ma to middle burdigalian 18 ma a period of tectonic instability preceded these events marked by normal and strike slip faulting as early as the mid eocene the two main directions of extension also recorded in southern yemen developed respectively oblique and normal to the n75e trend of the gulf of aden an anticlockwise succession of the two episodes from n20 to n160 only established in yemen accounts for the observed synrift fault pattern which is consistent with the type and geometry of faults predicted in analogue models of oblique rifting a latest phase of ns compression marked by strike slip faulting may represent a far echo of the arabia eurasia collision d 2002 elsevier science b v all rights reserved

the statistical characteristics of convective cells in a monsoon regime darwin northern australia abstract a season of operational cell and track data from darwin australia has been analyzed to explore the statistical characteristics of the convective cell heights the statistics for the monsoon and break regimes are significantly different with the break season cells being higher for a given reflectivity threshold the monsoon cells produce more rain but there are fewer intense cells and there is a much larger contribution from stratiform rain the monsoon cells are also slightly larger but shorter lived than the breaks the shorter lifetime may reflect a more rapid transition to a longer lived stratiform character the monsoon regime is shown to be associated with large scale ascent and higher humidity that may lead to more frequent but weaker cells within regimes the subset of intense cells generally reach near the tropopause or overshoot however there is little evidence in the data for a multimodal distribution of cell heights except perhaps for the intense monsoon cases instead the pi

impact of mesoscale meteorological processes on anomalous radar propagation conditions over the northern adriatic area the impact of mesoscale structures on the occurrence of anomalous propagation ap conditions for radio waves including ducts super refractive and subrefractive conditions were studied the chosen meteorological situations are the bora wind and the sporadic sea land breeze sb lb during three selected cases over a large portion of the northern adriatic for this purpose we used available radiosoundings and numerical mesoscale model simulations of real cases and their sensitivity tests at a horizontal resolution of 1 5 km and 81 vertical levels the model simulated the occurrences of ap conditions satisfactorily although their intensities and frequency were underestimated at times certain difficulties appeared in reproducing the vertical profile of the modified refractive index which is mainly dependent on the accuracy of the modeled humidity the spatial distributions of summer ap conditions reveal that the surface layer above the sea roughly between 30 and 100 m asl is often covered by super refractive conditions and ducts the sb is highly associated with the formations of ap conditions i in the first 100 m asl where trapping and super refractive conditions form because of the advection of cold and moist air and ii inside the transition layer between the sb body and the elevated return flow in the form of subrefractive conditions when deep convection occurs all three types of ap conditions are caused by the downdraft beneath the cumulonimbus cloud base in its mature phase that creates smaller but marked pools of cold and dry air the bora wind usually creates a pattern of ap conditions associated with the hydraulic jump and influences distribution of ap conditions over the sea surface

characterization and appraisal of facets influencing geochemistry of groundwater in the kulpawn sub basin of the white volta basin ghana groundwater composition in the kulpawn basin is largely controlled by aluminosilicates dissolution and cation exchange resulting in mainly ca mg hco3 and nahco3 water types principal component analysis piper graphical classification and stable isotope 18o and 2h of groundwater and surface water samples were used to delineate geochemical processes and groundwater facies the groundwater is mildly acid to neutral and low in conductivity chemical constituents except hco3 and sio2 have low concentration no cation shows clear majority however the order of relative abundance is na ca2 mg2 k hco3 is the predominant anion and the order of abundance is hco3 no3 so42 cl sio2 concentration is high compared with the major cations dissolution of plagioclase pyroxene and biotite and cation exchange are responsible for groundwater composition isotopic data suggest integrative smooth and rapid recharge from meteoric origin the groundwater quality is generally good for domestic usage however 18 and 47 of boreholes respectively have no3 and f levels outside who recommended limits suggesting potential physiological problems in some localities the groundwater has low sodium absorption ratio and low to moderate salinity hazard but significant magnesium hazard partially limiting its use for irrigation

performance evaluation of the earthquake detection and classification algorithm 2 ts tp of the seismic alert system of mexico sasmex abstract a performance evaluation of the detection and classification algorithm for earthquake early warning 2 t s t p was conducted to test its reliability and robustness the seismic alert system of mexico sasmex has used this algorithm since 1991 the algorithm estimates the rate of seismic energy released during two times the t s t p period based on the energy released it estimates an empirical magnitude range related to m b depending on the estimated m b either preventive or public alerts are issued in this article post facto tests are presented for 61 earthquakes for which sasmex issued an alert the algorithm was also tested on 31 earthquakes m w 6 0 that occurred in the mexican subduction zone from 1985 to 2014 these earthquakes occurred outside the coverage of the sasmex instruments at the time this dataset includes the 19 september 1985 m w 8 1 michoacan earthquake and the 9 october 1995 m w 8 0 colima event the algorithm was tested also on two great earthquakes the 22 february 2010 m w 8 8 maule chile earthquake and the 11 march 2011 m w 9 0 tohoku japan event the results of the evaluation of 144 acceleration records of the 61 earthquakes detected from the sasmex network indicate that 92 of the accelerograms of earthquakes with m b 6 0 have errors in the prediction of magnitude of less than 0 5 and 83 for m b 5 5 also the tests conducted on the 59 acceleration records of 31 earthquakes with m w 6 0 indicate that in all cases with the exception of one strong motion record the events are classified as m w 6 0 thus the algorithm shows a high level of reliability and robustness although the algorithm underestimates the magnitudes of large earthquakes these events are identified and classified as m w 6 0 thus an alert would be issued for these great earthquakes electronic supplement table of earthquake parameters performance of seismic alert system of mexico sasmex and specific performance evaluation of the 2 t s t p algorithm

effect of land use and urbanization on hydrochemistry and contamination of groundwater from taejon area korea abstract taejon metropolitan city located in the central part of south korea has grown and urbanized rapidly the city depends heavily on groundwater as a water resource because of ubiquitous pollution sources the quality and contamination have become important issues for the urban groundwater supply this study has investigated the chemical characteristics and the contamination of groundwater in relation to land use an attempt was made to distinguish anthrophogenic inputs from the influence of natural chemical weathering on the chemical composition of groundwater at taejon groundwater samples collected at 170 locations in the taejon area show very variable chemical composition of groundwater e g electrical conductance ranges from 65 to 1 290 s cm most groundwater is weakly acidic and the groundwater chemistry is more influenced by land use and urbanization than by aquifer rock type most groundwater from green areas and new town residential districts has low electrical conductance and is of ca hco 3 type whereas the chemical composition of groundwater from the old downtown and industrial district is shifted towards a ca cl no 3 so 4 type with high electrical conductance a number of groundwater samples in the urbanized area are contaminated by high nitrate and chlorine and exhibit high hardness the epco 2 that is the co 2 content of a water sample relative to pure water was computed to obtain more insight into the origin of co 2 and bicarbonate in the groundwater the co 2 concentration of groundwater in the urbanized area shows a rough positive relationship with the concentration of major inorganic components the sources of nitrate chlorine and excess co 2 in the groundwater are likely to be municipal wastes of unlined landfill sites leaky latrines and sewage lines chemical data of commercial mineral water from other jurassic granite areas were compared to the chemical composition of the groundwater in the taejon area factor analysis of the chemical data shows that the hco 3 and no 3 concentrations have the highest factor loadings on factor 1 and factor 2 respectively factors 1 and 2 represent major contributions from natural processes and human activities respectively the results of the factor analysis indicate that the levels of ca 2 mg 2 na cl and so 4 2 derive from both pollution sources and natural weathering reactions

reflection of seismic surface waves at the northern apennines abstract seismic surface waves with periods of 15 to 20 s are reflected laterally at the northern apennines for earthquakes originated and recorded in the wider alpine area a few hundred kilometres north of the apennines we can directly observe late arrivals of reflected regional surface waves these have a characteristic polarization of particle motion and often dominate the intermediate period surface wave coda love waves are the most prominent coda arrivals while reflected rayleigh waves show smaller amplitudes and become clear only after rotation of the recordings to the reflection incidence direction we can track the development of the love wave reflection along a temporary broad band transect across the northern apennines indicating the location of the reflector near to the highest topography from spectral element simulations of three dimensional wave propagation we attribute the reflection to a continuous 270 km long offset in the crust mantle boundary under the mountain belt with vertical throw of 20 km thus supporting a deep crustal root under the outer side of the apennines fold and thrust belt and significant crustal thinning on the inner side amplitude reflection coefficients for near normal incidence can be estimated as 7 for both love and rayleigh waves

centroid moment tensor solutions for january march 1997 abstract centroid moment tensor solutions are presented for 162 earthquakes that occurred during the first quarter of 1997 the solutions are obtained using corrections for aspherical earth structure represented by a whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward dziewonski a m woodward j h 1992 acoustic imaging at the planetary scale in h emert h p harjes eds acoustical imaging plenum new york 19 785 797 a new model of anelastic attenuation of durek and ekstrom durek j j ekstrom g 1996 a radial model of anelasticity consistent with long period surface wave attenuation bull seismol soc am 86 144 158 is used to predict the decay of the waveforms

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

on elevated fluoride and boron concentrations in groundwaters associated with the lake saint martin impact structure manitoba abstract hydrogeological investigations conducted by the geological survey of canada in the lake saint martin region of manitoba have confirmed earlier reports of naturally elevated f and b concentrations in local groundwaters fluoride and b concentrations are highly correlated r 2 0 905 and reach 15 1 mg l and 8 5 mg l respectively virtually all groundwaters with f concentrations greater than the drinking water limit of 1 5 mg l are from wells within the lake saint martin impact structure a 208 ma complex crater 23 km in diameter underlying a large part of the study area the high f groundwaters can be classified into two groups according to their anionic and isotopic compositions group i samples consist of na mixed anion groundwaters with cl greater than 100 mg l and highly depleted 18 o compositions indicative of recharge under much cooler climatic conditions than at present samples belonging to this group exhibit a striking relationship to crater morphology and are found in an arcuate belt within the southern rim of the impact structure group ii high f samples consist of na hco 3 so 4 groundwaters with little cl and less depleted 18 o compositions samples belonging to this group are associated with groundwaters recharged locally on a low ridge within the impact structure this paper traces the probable source of high f groundwaters to phosphatic pellets in shales of the winnipeg formation a regional basal clastic unit which sub crops at shallow depth beneath the crater rim as a result of more than 200 m of structural uplift associated with the impact event this extensive aquifer is known elsewhere in southern manitoba for its naturally softened groundwaters and locally elevated f concentrations group i groundwaters are interpreted as discharge from the winnipeg formation where it abuts against crater fill deposits group ii high f groundwaters are interpreted as modern recharge from within the impact structure displacing group i groundwaters thus elevated f and b concentrations observed in groundwaters of the lake saint martin area represent the geochemical signature of upwelling from a deep regional aquifer the previously unsuspected discharge zone occurs within an isolated sub crop of the aquifer formed as a result of structural uplift caused by the impact event

the levels of fluorine in the sediments of the aquifer and their significance for fluorosis in coastal region of laizhou bay china the levels of fluorine in sediment cores obtained from changyi county pz core and laizhou county ts core are used to discuss the fluorine sources in groundwater and its enrichment dynamics the sediments in the aquifer are mainly constituted of granite gravels the levels of fluorine in the pz and ts cores range from 130 to 468 mg kg 139 528 mg kg with average values of 324 348 mg kg respectively which show relatively lower levels than the national average of fluorine in the soil or sediment thus the fluorosis in this area should not be attributed to the levels of fluorine in sediments the average fluorine concentrations in the aquifer from top to bottom are 154 139 200 222 mg kg for the ts core and 154 130 266 272 mg kg for the pz core respectively which are the lowest of the cores and extremely lower levels than the fresh granites such a fact indicates that a vast amount of fluorine has been leached into the groundwater moreover the fluorine leachability is estimated to be approximately 70 although the previous documents showed fluorine contents of the granite surrounding laizhou bay were almost equal to or even lower than the average levels of fluorine in fresh granites meanwhile a simulation experiment also reveals that fluorine release from rocks increases with the addition of seawater and brine water therefore the seawater intrusion may potentially enhance the fluorine leachability and should be an important dynamic of fluorine enrichment

convective rain cells radar derived spatiotemporal characteristics and synoptic patterns over the eastern mediterranean 1 this paper examines the spatiotemporal characteristics of convective rain cells over the eastern mediterranean northern israel and their relationship to synoptic patterns information on rain cell features was extracted from high resolution weather radar data the radar gauge adjustment validation cell segmentation and tracking techniques are discussed at length at the beginning of the paper convective rain cells were clustered into three synoptic types two winter lows deep cyprus lows and shallow lows and one tropical intrusion active red sea trough using several ncep ncar parameters and empirical distributions were computed for their spatial and temporal features in the study region it was found that the active red sea trough rain cells are larger live for less time and possess lower rain intensities than the rain cells generated by the winter lows the cyprus low rain cells were found to be less intense and slightly larger on average than the shallow low rain cells it was further discovered that the preferential orientation of the rain cells is associated with the direction and velocity of the wind the effect of distance from the coastline was also examined an increase in the number and area of the rain cells near the coastline was observed presumably due to the sea breeze convection the mean rainfall intensity was found to peak near the shore and decrease with distance inland this information is of great importance for understanding rain patterns and can be further applied in exploring the hydrological responses of the basins in this region

fluoride hydrogeochemistry in alluvial aquifer an implication to chemical weathering and ion exchange phenomena fluoride f concentration in some parts of the quaternary alluvial aquifer of birbhum district west bengal india varies from 0 31 to 13 61 mg l with an average of 3 13 mg l high f groundwater mostly belongs to na hco3 type isotopic signature suggests that most of the groundwater having fast recharge component either from flowing canals or rainfall contains relatively less f 2 mg l and relatively depleted 18o content 18o 5 to 4 on the other hand some of the groundwaters having relatively depleted 18o 4 to 3 do exhibit f in the range of 4 13 mg l average ratio of na na k 0 69 and cl cl hco3 0 25 with average tds 267 5 mg l represents that the weathering of aquifer sediments or sediment water interaction primarily controls the major ion chemistry particularly f concentration of groundwater in this region this idea is further strengthened by the relationship between na k and total cations tz and na cl molar ratio moreover groundwater is under saturated with respect to amorphous silica average sisio2 a 0 64 while all water samples are either saturated or super saturated with respect to quartz average siquartz 0 66 mineral stability diagrams for the nao h2o al2o3 sio2 and k2o h2o al2o3 sio2 systems suggest that most stable silicate mineral phase in the aquifers is kaolinite suggesting that semi arid nature of the study area and intermediated flow condition may give rise to kaolinite sample falling in kaolinite stability field indicates that the hydrolysis of some alumino silicate minerals such as albite and biotite is responsible for the formation of hco3 na and k which are dominant in the groundwaters this ultimately leads to higher rate of ion exchange of f from biotite and muscovite rich aquifer matrix to groundwater of the study area

hydrochemical characteristics of groundwater and surface water for domestic and irrigation purposes in vea catchment northern ghana the vea catchment mainly underlain by crystalline basement rocks is located in northern ghana hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes influencing water quality and suitability of surface and groundwater for agricultural and domestic uses sixty one groundwater and four surface water samples were collected from boreholes dams and rivers and analysed for ca2 mg2 na k hco3 cl and so4 2 fetot po4 3 mntot nh4 no3 no2 in addition ph total dissolved solids electrical conductivity total hardness turbidity colour salinity and dissolved oxygen were analysed chloro alkaline indices 1 and 2 and characterization of weathering processes suggest that the chemistry of groundwater is dominated by the interaction between water and rocks cation exchange and silicate weathering are the dominant processes controlling the chemical composition of the groundwater in the area studied mineral saturation indices indicate the presence of at least three groups of groundwater in the vea catchment with respect to residence time the meteoric genesis index suggests that 86 of the water samples belong to the shallow meteoric water percolation type the findings further suggest that the groundwater and surface water in the basin studied are mainly ca mg hco3 water type regardless of the geology compared to the water quality guidelines of who the study results on sodium absorption ratio sodium percentage magnesium hazard permeability index and residual sodium carbonate indicate that groundwater and surface water in the vea catchment are generally suitable for drinking and irrigation purposes

motion of the philippine sea plate consistent with the nuvel 1a model summary we determine euler vectors for 12 plates including the philippine sea plate ph relative to the fixed pacific plate pa by inverting the earthquake slip vectors along the boundaries of the philippine sea plate gps observed velocities and 1122 data from the nuvel 1 and the nuvel 1a global plate motion model respectively this analysis thus also yields euler vectors for the philippine sea plate relative to adjacent plates our results are consistent with observed data and can satisfy the geological and geophysical constraints along the caroline cr ph and pa cr boundaries the results also give insight into internal deformation of the philippine sea plate the area enclosed by the ryukyu trench nankai trough izu bonin trench and gps stations s102 s063 and okino torishima moves uniformly as a rigid plate but the areas near the philippine trench mariana trough and yap palau trench have obvious deformation

hydrochemical borehole logs characterizing fluoride contamination in a crystalline aquifer maheshwaram india summary hydrochemical borehole loggings with a submersible idronaut ocean seven 302 multiparameter probe equipped of f and no 3 ion selective electrodes in combination with ec ph and dissolved oxygen were applied for characterizing fluoride f contamination in a crystalline hard rock aquifer of a small indian agricultural watershed where groundwater is intensively abstracted for rice irrigation a high accuracy of f concentrations determined in situ shown by comparing with laboratory analyses was obtained through using conductivity logs for ionic strength consideration large variations in chemical composition and particularly of f concentration were observed inside boreholes though restricted to the weathered fractured layer down to 30 35 m depth this conforms to the hydrogeological model of a crystalline aquifer where most groundwater flow occurs in the shallow part of the fractured zone the general trend of increasing f content with depth results from f accumulation through water rock interaction but the shape of the f profile depends on the connectivity of the fracture network close to the borehole the concentrations seen within the water table fluctuation zone locally suggest f input from fertilizers in groundwater in addition to the earlier demonstrated role of evaporation from irrigation return flow it is also likely that locally the deepening of boreholes has contributed to increasing the population s vulnerability by tapping f enriched groundwater at depth

reappraisal of the arabia india somalia triple junction kinematics abstract we propose alternative kinematics for the arabia india somalia triple junction based on a re interpretation of seismological and magnetic data the new triple junction of the ridge ridge ridge type is located at the bend of the sheba ridge in the eastern gulf of aden at 14 5 n and 56 4 e the owen fracture zone arabia india boundary is connected to the sheba ridge by an ultra slow divergent boundary trending n80 e 10 marked by diffuse seismicity the location of the arabia india rotation pole is constrained at 14 1 n and 71 2 e by fitting the active part of the owen fracture zone with a small circle the finite kinematics of the triple junction is inferred from the present day kinematics since the inception of the accretion 15 18 ma ago the sheba ridge has probably receded 300 km at the expense of the carlsberg ridge which propagated northwestward in the gulf of aden while an ultra slow divergent plate boundary developed between the arabian and indian plates the overall geometry of the new triple junction is very similar to that of the azores triple junction

assessing the impact of natural and anthropogenic activities on groundwater quality in coastal alluvial aquifers of the lower liaohe river plain ne china abstract the lower liaohe river plain lrp is an economically and ecologically important area situated on an alluvial plain where anthropogenic activities are very intensive field investigations were conducted in the lrp and 15 water quality parameters surveyed at 216 wells during september and october of 2009 and 2010 these showed significant variation in the hydrochemistry of groundwater throughout the plain a piper plot was used to identify the major geochemical processes occurring in the entire plain principal components analysis pca was used to identify various underlying natural and anthropogenic processes that created these distinct water types the stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the liaohe river delta five principal components pcs were extracted in terms of pca which can be invoked to explain 82 of the total variance in water quality parameters the pca results can be categorized by five major factors 1 holocene transgression and mixing 2 surface water infiltration 3 multi factor processes 4 rainfall and agricultural fertilizer contamination and 5 geogenic f enrichment this study demonstrates that the great variation of groundwater hydrochemistry in the lrp should be attributed to both natural and anthropogenic processes

the groundwater recharge regime of some slightly metamorphosed neoproterozoic sedimentary rocks an application of natural environmental tracers isotope data of precipitation and groundwater in parts of the voltaian basin in northern ghana were used to explain the groundwater recharge regime in the area groundwater recharge is an important parameter in the development of a decision support system for the management and efficient utilization of groundwater resources in the area it is therefore important to establish the processes and sources of groundwater recharge 18o and 2h data for local precipitation suggest enrichment relative to the global meteoric water line gmwl and indicate that precipitation takes place at a relative humidity less than 100 the groundwater data plot on an evaporation line with a slope of 5 suggesting a high degree of evaporative enrichment of the precipitation in the process of vertical infiltration and percolation through the unsaturated zone into the saturated zone this finding is consistent with the observation of high evapotranspiration rates in the area and ties in with the fact that significant clay fraction in the unsaturated zone limits vertical percolation and thus exposes the percolating rainwater to the effects of high temperatures and low humidities resulting in high evapotranspiration rates groundwater recharge estimates from the chloride mass balance cmb method suggest recharge in the range of 1 8 32 of the annual average precipitation in the form of rainfall the highest rates are associated with areas where open wells encourage significant amount of groundwater recharge from precipitation in the area in the northern parts of the study area groundwater recharge is lower than 12 the recharge so computed through the application of the cmb methodology takes on a spatial distribution akin to the converse of the spatial pattern of both 18o and 2h in the area as such the locations of the highest recharge are associated with the most depleted values of the two isotopes this observation is consistent with the assertion that low vertical hydraulic conductivities slow down vertical percolation of precipitation down to the groundwater water the percolating precipitation water thus gets enriched in the heavier isotopes through high evapotranspiration rates at the same time the amount of water that finally reaches the water table is considerably reduced copyright 2013 john wiley sons ltd

the source of fluoride toxicity in muteh area isfahan iran endemic dental fluorosis has been observed in most inhabitants of three villages of muteh area located in northwest of isfahan province with mottled enamel related to high levels of fluoride in drinking water 1 8 2 2 ppm forty seven groundwater samples from six villages were collected and fluoride concentrations along with physico chemical parameters were analyzed fluoride concentration in this area varies from 0 2 to 9 2 mg l with highest fluoride level at muteh gold mine chahkhatun mine fluoride concentration positively correlates with ph and hco3 indicating that alkaline ph provides a suitable condition for leaching of fluoride from surrounding rocks the district is mainly covered by three lithological units namely metamorphic and granite rocks alluvial sediments and carbonate rocks factor analysis shows that parameters can be classified into four components electrical conductivity ec total dissolved solids tds cl na and k ph and f so4 2 and mg2 hco3 and ca2 the groundwaters from the three geological units were compared using mann whitney u test the order of median fluoride concentration is metamorphic and granite rocks alluvial sediments carbonate rocks hence the fluoride content is most probably related to fluoride bearing minerals such as amphibole and mica group minerals in metamorphic and granitic rocks the concentration of fluoride in drinking water wells located near the metamorphic complex in muteh area is above 2 ppm

factors controlling fluoride contents of groundwater in north central and northwestern sri lanka chemical characterization has been made of groundwater bodies at 294 locations in four village districts in north central and northwestern sri lanka with special focus on fluorine contamination high fluoride contents in groundwater are becoming a major problem in the dry zone of sri lanka and dental fluorosis and renal failures are widespread field measurements of temperature ph and electrical conductivity were made during sampling chemical analyses of the water samples were later made using atomic absorption spectroscopy spectrophotometry and titration fluoride concentrations in the study area vary from 0 01 to 4 34 mg l and depend on ph and the concentrations of na ca and hco3 basement rocks including hornblende biotite gneiss biotite gneiss and granitic gneiss seem to have contributed to the anomalous concentrations of fluoride in the groundwater longer residence time in aquifers within fractured crystalline bedrocks may enhance fluoride levels in the groundwater in these areas in addition elevated fluoride concentrations in shallow groundwater in intensive agricultural areas appear to be related to the leaching of fluoride from soils due to successive irrigation

worldwide doublets of large shallow earthquakes abstract we investigated all the pairs of mw 7 5 shallow earthquakes in the harvard catalog that occurred at a centroid distance of less than 100 km we showed that most of these pairs have similar focal mechanisms because these earthquakes generally should have focal regions in excess of 100 km diameter their rupture zones apparently intersect for all these pairs the time interval is significantly less than the time span needed for plate motion to accumulate the strain released by the first event these observations conflict strongly with quasi periodic recurrence models on which the seismic gap hypothesis is based power law recurrence fits these earthquake ob servations much better introduction many models used to forecast long term seismic hazard are based on the quasi periodic or seismic cycle hypothesis of large earthquake occurrence this hypothesis assumes that the probability of a large earthquake is low after signifi cant release of seismic energy and that danger increases only when tectonic plate motion accumulates strain sufficient for a new strong event several models have been formulated to apply this idea to long term earthquake prediction mccann

micro tsunami from a local interplate earthquake detected by cabled offshore tsunami observation in northeastern japan a micro tsunami from an interplate earthquake mw 6 1 was observed in 1998 on ocean bottom tsunami meters obtms deployed east off the northeastern japan the offshore tsunami data without complex distortions due to the coastal topography enable us to estimate reliable tsunami source parameters the observed amplitude was about 1 5 cm at epicentral distance less than 100 km we numerically computed the tsunami waveform by solving the linear boussinesq equations the observed tsunami waveforms are well explained by synthetic waveforms assuming the fault width of 10 15 km the depth of the fault is estimated as 5 10 km below the seafloor which is in good agreement with the location of the plate boundary defined by previous seismic studies

fluoride concentrations in a crystalline bedrock aquifer marathon county wisconsin water samples from 2 789 private water supply wells in marathon county wisconsin reveal that fluoride concentrations in the crystalline bedrock range from 0 01 to 7 60 mg l with 0 6 of the values exceeding the environmental protection agency s epa s maximum contaminant level of 4 mg l and 8 6 exceeding the epa s secondary maximum contaminant level of 2 0 mg l roughly a quarter of the wells contain dissolve fluoride within the range considered optimal for human health between 0 5 and 1 5 mg l whereas 63 3 fall below 0 5 mg l consistent with studies conducted in other regions felsic rocks have significantly higher fluoride concentrations than mafic and metasedimentary rocks syenites yield the most fluoriferous groundwaters but the highest median concentration occurs in a sodium plagioclase granite a relationship between plagioclase composition and fluoride concentrations suggests that dissolved fluoride levels are controlled by fluorite solubility and that higher fluoride concentrations are found in soft sodium rich groundwater

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

fluoride dynamics in the granitic aquifer of the wailapally watershed nalgonda district india high concentrations of fluoride up to 7 6 mg l are a recognized feature of the wailapally granitic aquifer of nalgonda district andhra pradesh india the basement rocks provide abundant sources of f in the form of amphibole biotite fluorite and apatite the whole rock concentrations of f in the aquifer are in the range 240 990 mg kg calcretes from the shallow weathered horizons also contain comparably high concentrations of f 635 950 mg kg the concentrations of water soluble f in the granitic rocks and the calcretes are usually low 1 of the total or less but broadly correlate with the concentrations observed in groundwaters in the local vicinity the water soluble fraction of fluoride is relatively high in weathered calcretes compared to fresh calcretes groundwater major ion composition shows a well defined trend with flow downgradient in the wailapally aquifer from na ca hco3 dominated waters in the recharge area at the upper part of the catchment through to na mg hco3 and ultimately to na hco3 and na hco3 cl types in the discharge area in the lowest part the evolution occurs over a reach spanning some 17 km groundwater chemistry evolves by silicate weathering reactions although groundwaters rapidly reach equilibrium with carbonate minerals favouring precipitation of calcite and ultimately dolomite in the lower parts of the watershed this precipitation is also aided by evapotranspiration decreasing ca activity downgradient leads to a dominance of fluorite undersaturated conditions and consequently to mobilisation of f despite the clear downgradient evolution of major ion chemistry concentrations of f remain relatively uniform in the fluorite undersaturated groundwaters most being in the range 3 0 7 6 mg l the rather narrow range is attributed to a mechanism of co precipitation with and or adsorption to calcrete in the lower sections of the aquifer the model may find application in other high f groundwaters from granitic aquifers of semi arid regions

centroid moment tensor solutions for april june 1998 abstract centroid moment tensor solutions are presented for 219 earthquakes that occurred during the second quarter of 1998 the solutions are obtained using corrections for aspherical earth structure represented by a whole mantle shear velocity model sh8 u4l8 of dziewonski and woodward dziewonski a m woodward r l 1992 acoustic imaging at the planetary scale in emert h harjes h p eds acoustical imaging plenum vol 19 pp 785 797 a new model of anelastic attenuation of durek and ekstrom durek j j ekstrom g 1996 a radial model of anelasticity consistent with long period surface wave attenuation bull seismol soc am 86 144 158 is used to predict the decay of the waveforms

sources distributions of fluoride in waters and its influencing factors from an endemic fluorosis region in central guizhou china the use of high fluoride content coal caused the severe coal burning endemic fluorosis in zhijin county guizhou province china the long term mine exploitation in this region is as an important source of acid mine drainage amd and leads to the release of potential fluoride f into the surrounding waters aiming to investigate the source hydrogeochemical characteristics and influencing factors of fluoride in waters of this area a hydrogeological and geochemical research has been conducted in this study samples of various types of waters were collected and analyzed for major cations major anions and tfe al selected coal and gangue samples were analyzed for fluoride contents the f concentration in amd or amd affected waters ranged from 0 27 to 4 94 mg l and f was mainly enriched in na so4 and mg so4 waters but a relatively low f concentration was found in the ca so4 water the f concentration in the ca hco3 water without being affected by amd ranged from 0 01 to 0 20 mg l the elevated f contents were found in the amd which is mainly influenced by the local coal mining activities and it is resulted from the dissolution of fluoride bearing minerals in coal bearing clastic rocks as well as the low ph values high al and fe concentrations high total dissolved solids and high al f ratio of the amd in addition the dissolution precipitation of carbonate rocks and special hydrogeological conditions determined the f concentration in surface water meanwhile the climate is also an influencing factor that cannot be ignored to affect the f concentrations of surface water and groundwater