fracture and separation histories of stretched belemnites and other rigid brittle inclusions in tectonites abstract apparent extension of a stretched rigid inclusion e r l f l 0 1 where l 0 and l f are original and final lengths respectively is always less than strain reversal extension e f calculated by sequentially closing inter fragment gaps until the inclusion is restored to its original length differences between the two measures are strongly influenced by the number of fractures n and their timing within the total stretch history and weakly influenced by the fracture location several fracture and separation models are established to explore these differences using monte carlo simulations all normalized to e r 0 5 when fragment and gap lengths are random and uncorrelated e f values fall in the range 0 5 e f e f values the expected mean value is still much greater than 0 5 when n is small but approaches e r with increasing n and with decreasing time interval between successive fractures model predictions are compared with stretched belemnites in the external french alps results indicate that belemnite fracturing continued throughout a substantial proportion of total stretch history the proportion varying from locality to locality and correlating strongly with maximum stretch recorded this probably reflects variations in stress and suggests that if constant rheology is assumed stretched belemnites may be used to estimate relative strain rates as well as absolute strains

continuous monitoring of fumarole temperatures at mount etna italy abstract in this paper we present the first data of temperature continuously recorded in two fumarole fields designated vor and hor located in the summit area of mount etna volcano italy the time series embraces two distinct periods 1 october 2007 to november 2009 during which an effusive eruption occurred from may 2008 to july 2009 and 2 november 2011 to june 2012 characterized by the occurrence of strong paroxysms fire fountains and lava flow the analysis of the temperature signal in both the time and frequency domains and its comparison with meteorological observations allowed us to separate the exogenous influences from the effects of variations in the activity state of the volcano the acquired data were weakly affected by seasonal cycles of the air temperature and strongly affected by the rainfall optimization of site conditions i e sensor depth and soil permeability markedly reduced meteorological disturbances the distance from the main degassing and or eruptive fractures was crucial to maximizing the probability of the technical survival of the monitoring apparatus which was seriously affected by the emission of acidic gases tephra fallout and lava flows apart from the exogenous influences the most appreciable variation was observed at vor where a huge increase in fumarole temperature was detected immediately after the onset of the 2008 2009 eruption such an anomalous increase was attributed to the rapid ascent of magma feeding the eruptive fracture another abrupt increase in temperature was recorded at hor in march and april 2012 during this period the frequency of paroxysm occurrence increased markedly and this led us to hypothesize that the thermal anomaly was due to the intrusion of a new batch of magma in the conduits of the southeast crater medium to long term monitoring weeks to months of fumarole temperatures revealed variations that were attributed to pressurization depressurization phases of the shallow volcanic system which varied between the various monitored sectors of the volcano our observations suggest that continuous monitoring of fumarole temperature can give useful information about the activity of mount etna moreover due to the complexity of its shallow plumbing system we conclude that the monitoring systems should be extended to cover the entire fumarole network of the summit area

continuous chemical monitoring of volcanic gas in izu oshima volcano japan abstract a new continuous monitoring system has been developed for the measurement of volcanic gas from the steam well located 3 km north from the summit of izu oshima volcano japan after removing the water vapor using three sequential dehydration methods co 2 and so 2 contents are measured using ir sensors and o 2 and h 2 using a zirconia sensor and a semiconductor sensor respectively this system has been in operation without any significant trouble for 3 years the dehydrated volcanic gas from the well consists of a mixture of co 2 o 2 and n 2 a decreasing trend of the co 2 content was observed from 1995 to 1998 together with a decrease of volcanic activity seasonal changes have also been observed in co 2 and o 2 contents co 2 being higher and o 2 lower in summer which suggests larger contribution of magmatic components in summer while changes in short term variation in co 2 and o 2 are influenced by atmospheric pressure changes the co 2 content correlates inversely with atmospheric pressure unlike o 2 with some hours delay in contrast the h 2 content increased intermittently up to 1200 ppm one to several hours after a sudden drop in the atmospheric pressure and without any apparent correlation with seasonal changes this system allows us to study temporal variation in chemical composition of volcanic gas during quiescent periods of volcanic activity of izu oshima volcano and might help us detect anomalous changes before future eruptive events

how to remove the seasonal atmospheric effect an application on a surface volcanic temperature at nisyros active volcano hellenic volcanic arc abstract surface temperature at a volcanic system is the result of a mixture of two heat sources originating one from above and another from below the ground surface the atmosphere significantly affects the surface s temperature of the volcano and removal of the atmospheric effect is required for meaningful interpretations prior to any characterization of anomalous volcanic activity time series of meteorological data were acquired from the closest weather station to nisyros volcano and surface volcanic temperature from the southern part of nisyros caldera were analyzed time series analysis took place at different time scales through a decomposition method the decomposition of the time series into long seasonal and short term components was performed by the application of the kolmogorov zurbenko kz filter to separate the noise that appears on the obtained data the time series regression tsr model was applied in all time scales the long and the short term components of the surface volcanic temperature show no significant correlation with the atmospheric variables while the seasonal term indicates a very strong association with an r2 equal with 99 after the removal of the atmospheric effect our model indicates that there is a normal activity of the seasonal heat emission in nisyros with no anomalous signals in the temperature residuals during our survey this methodology may facilitate the process of filtering a seasonal atmospheric effect and better comprehend the heat emission of a volcano hydrothermal system from temperature surface readings

convective boundary layer evolution to 4 km asl over high alpine terrain airborne lidar observations in the alps mountain ranges have important influences on the structure and composition of the convective boundary layer cbl and free troposphere ft evolution of the summer cbl measured over the european alps using airborne lidar was clearly observed to attain a near uniform height up to 4 2 km asl by early afternoon a climatology of in situ high alpine aerosol measurements suggests that such substantial growth corresponding to 0 3 of the mid latitude tropopause height often occurs during summer months subsequent nocturnal collapse of the cbl was estimated to result in the venting of 0 8 0 3 so44 gg day 1 into a ft residual layer leeward of the alps

volcanic gas concentration and aquifer permeability estimated from tidal fluctuations in groundwater level case of koshimizu well in izu oshima japan in order to understand the mechanism of material transport induced by seismic and volcanic activities we analyzed chemical changes and permeability variations based on field observations on a recently active volcano izu oshima from march to august 1988 when the volcanic and seismic activities in izu oshima declined following an episode of those activities that ended in late 1987 the concentrations of co2 and h2 of volcanic origin increased 10 30 times above the previous levels in the koshimizu well located 1 km from the coast analysis of tidal frequency groundwater level variations in the well shows changes in tidal response of the groundwater level that are inferred to be associated with changes in shallow formation permeability a simple 1 dimensional diffusion model together with reasonable assumption about the local hydrologic structure suggest that the horizontal permeability in the upper few hundred meters of the island is high of the order of 10 8 m and varied by as much as 20 percent during recorded period we consider that these changes should be the results of vertical development of cracks which was caused by hot water intrusion from magma

continuous gas monitoring at galeras volcano colombia first evidence abstract this paper describes a system of instruments for continuously monitoring fumarolic gases which is installed at galeras volcano colombia several parameters such as the concentration of co2 and rn in the fumarolic emissions as well as the temperature of the gases and their pressure are measured every 6 s we report variations in these parameters which were observed during a short flurry of seismic activity at the volcano at this stage it is uncertain whether the changes in the parameters are directly associated with volcanic processes from the data presented here we can conclude that ambient air can enter the fumarolic vent system in consequence the fumarole may be influenced by the direction and strength of the wind

continuous monitoring of distal gas emanations at vulcano southern italy the increasing activity of vulcano island italy since 1985 led to the initiation of continuous geochemical monitoring of the lateral soil gas emissions on the basis both of their relative geochemical characteristics and of local considerations three gaseous components were selected for monitoring namely co2 he and 222rn monitoring has been performed by means of specific analysers gases extracted from a water well located at the foot of the active cone were selected for monitoring on the basis of their geochemical and isotopic characters that indicate their genetic link with central high temperature fumarolic gases emitted at the crater very strong variations of gas composition can be observed within one day from 1 to about 94 for co2 some variations display a daily character and can be correlated with that of atmospheric pressure the three monitored gases are highly correlated suggesting very high kinetics of gas transfer in the system because of these considerable variations of chemical composition bulk concentrations obviously are not suitable for monitoring at vulcano however the evolution with time of ratios such as 222rn co2 and he co2 the latter being corrected for atmospheric contamination supplies numerical parameters that the expected to characterize the intensity of the degassing process a new input of magmatic gases that would lead to an increase in the 222rn co2 and he co2 ratios should therefore be detected by such a monitoring station

observation of convection initiation processes with a suite of state of the art research instruments during cops iop 8b in the afternoon of 15 july 2007 a thunderstorm was initiated within a line of cumulus clouds which formed parallel to the crest of the black forest mountains during the intensive observation period iop 8b of the convective and orographically induced precipitation study cops this paper extends the analysis of processes that led to convection initiation ci i e the transition from shallow to deep convection on this day with the data from several cops instruments that have not been considered in previous studies in particular the boundary layer structure lids and the water vapour field in the pre convective environment of the event are discussed for this purpose we investigated measurements of water vapour lidars temperature lidars and wind lidars profiles from radiosondes in situ aircraft data and gridded data of weather stations as well as gps integrated water vapour data and satellite imagery thermally driven circulation systems formed over both the black forest and the vosges mountain ranges which resulted in local convergence zones these superimposed with the large scale convergence in the black forest area in the presence of sufficient moisture and updraught clouds formed close to the mountain crests the related latent heat release allowed larger thermals to be produced which may have had a positive feedback on stabilizing these convergence zones as a whole we believe that differences in the moisture field explain why convection remained shallow and sparse over the vosges mountains because these differences were responsible for differences in convective inhibition cin the stationary location of the convergence zone over the southern black forest was probably decisive for ci because it constantly transported sensible and latent heat into the area in which ci took place

boundary layer energy transport and cumulus development over a heated mountain an observational study abstract aircraft and surface measurements of the boundary layer transport of mass and moisture toward an isolated heated mountain are presented the data were collected around the santa catalina mountains in arizona 20 30 km in diameter during the north american monsoon on days with weak winds and cumulus congestus to cumulonimbus development over the mountain flights in the boundary layer around the mountain and surface station data indicate that mountain scale anabatic surface wind generally develops shortly after sunrise peaking at 1 m s 1 in strength close to solar noon there is some evidence for a toroidal heat island circulation with divergence in the upper boundary layer the aircraft data and mainly the diurnal surface temperature and pressure patterns confirm that this circulation is driven by surface heating over the mountain three case studies suggest that growth spurts of orographic cumulus and cumulonimbus are not preceded by enhanced mountain scale mass convergence near the surfac

origin of hydrogen and carbon dioxide in fault gases and its relation to fault activity gases occluded in fracture zones of active faults are characterized by a high concentration of h 2 and or co 2 a predominant gas species h 2 or co 2 is related to the lithofacies which the fault cuts carbon dioxide concentration in sediments fluctuates with temperature this evidence and sigma 13 c of co 2 about 20 suggests that co 2 originates from organic materials carbon dioxide with sigma 13 c of 5 to 17 in brecciated gneiss containing marble may have been produced by interaction between organically derived co 2 and the marble or alternatively may have been magmatically derived hydrogen usually occurs in sheared silicate rocks and its concentration fluctuates a great deal the concentration of h 2 from active faults associated with historical earthquakes usually amounts to as high as several percent in maximum whereas the concentration of h 2 from quaternary faults not associated with historical earthquakes is at most 1

on the boundary layer structure over highly complex terrain key findings from map within map one of the scientific projects was devoted to boundary layers in complex terrain in a number of subprojects boundary layer issues were addressed and detailed high resolution multi sensor observations were combined with simulation by models allowing for adequate parametrization of turbulence processes in this contribution the projects are briefly introduced and an attempt is made to summarize their key findings and to put them into a joint perspective spatial variability is found to be large but strictly related to topography and therefore allowing for possible parametrization traditional boundary layer scaling approaches cannot simply be applied over highly complex topography but some of the map findings suggest the potential for suitable extensions of those scaling relations to cover various cases of complex terrain the mean boundary layer structure and thermally driven flows in narrow valleys are found not to be generally in line with previous results from larger valleys elsewhere furthermore local circulations are reported to contribute considerably to exchange between valley and free troposphere in particular the range of their effects on the lower atmosphere seems to be larger than just turbulent transport within the planetary boundary layer would suggest thus in larger scale numerical models where the topography is not resolved possible sub grid parametrizations for local exchange seem to be in order copyright 2007 royal meteorological society

strain analysis in rocks with pretectonic fabrics abstract a major problem in strain analysis of ellipsoidal fabrics is how to separate the effects of initial preferred orientation of objects from the effects of strain new algebraic methods are presented here which apply to many of the situations previously analysed by graphical and iterative techniques the algebraic solutions are simple and highlight some assumptions implicit in previous methods and the relations between those methods it is shown that many final ellipsoidal fabrics cannot be produced from initial fabrics which were symmetric with respect to bedding and that a three dimensional analysis is preferable to analysis on two dimensional section planes

secular variations in helium isotope ratios in an active volcano eruption and plug hypothesis abstract secular variations in 3 he 4 he and 4 he 20 ne ratios are reported for october 1986 to april 1991 in gas samples from a 90 c steam well located about 3 km north of mt mihara an active volcano in izu oshima island japan the 3 he 4 he and 4 he 20 ne ratios increased anomalously from 4 18 r atm to 4 59 r atm and from 0 93 to 1 08 respectively about 3 months prior to the explosive eruption of the volcano on 4 october 1990 the 3 he 4 he enhancement may be related to the concurrent decrease in height of volcanic smoke at the central cone the gas pressure in the conduit may have significantly increased before the eruption owing to solidified cap lava or ash in the cone which may have strengthened the transfer of magmatic helium from the source to the observation well through fissures or permeable channels in the volcanic edifice

secular variations of carbon and helium isotopes at izu oshima volcano japan abstract secular variations in 13c 12c ratios and chemical compositions of gas samples from october 1986 to july 1992 are reported from a 92 95 c steam well located about 3 km north of mt mihara an active volcano on izu oshima island japan the 13c value steeply increased from 2 97 relative to pdb carbonate in december 1986 to 1 15 in march 1988 and then gradually decreased to 1 75 in july 1992 over the same period the co 2 content changed similarly with time even though the experimental error is relatively large these variations are consistent with helium isotope changes initially rapid and then slow enhancements of 3he 4he ratio 13c value and co 2 content are invoked by violent eruptions of izu oshima volcano from 15 november to 18 december 1986 after the eruptive activity depletion of magmatic gas emission and subsequent mixing with crustal fluids in the hydrothermal system may produce the gradual decreases of 3he 4he ratio 13c value and co 2 content taking into account the rates of these decreases we suggest that helium and carbon isotope ratios will return to the situation of before the magmatic eruption within 15 years

h2 generation by reaction between h2o and crushed rock an experimental study on h2 degassing from the active fault zone granite and quartz were crushed under moist conditions in the temperature range of 25 270 c in order to obtain the information on the mechanism operative for h2 degassing along active faults it was found that the amounts of h2 gas released by crushing granite and quartz increased with temperature up to around 200 c and then decreased suddenly the results indicate that h2 gas is generated by a chemical reaction between water and such radicals as si and si o formed on the fresh surfaces when the si o si bonds are destroyed by crushing and that the existence of a maximum for amount of h2 gas is due to the decrease of the lifetime of si o radical at the temperature higher than about 200 c the results lend credence to the possibility that h2 gas is generated in the temperature range of 25 270 c along the active fault through the reaction between groundwater and the fresh surfaces of underground rocks formed by the fault movements

belemnites strain analysis and regional tectonics a critical appraisal abstract deformed belemnites offer great potential for estimating strain in deformed rocks there are two fundamental approaches 1 fragmentation and 2 reorientation of the belemnite guard the fragmentation approach is based on measurements of the original fragment and final fragment plus intervening gap belemnite lengths three variants exist standard ramsay strain reversal ferguson and modified standard hossain methods of which the second is the most accurate but also the slowest the third method is both simple and relatively accurate strain ellipse estimates are conventionally determined from the best fit envelope to plots of belemnite elongation 1 e against orientation badoux beach method but this demands a large number of belemnites per locality we describe an improved strain ellipse construction which requires only few belemnites the reorientation approach is based on strain induced shape modification of belemnite orientation distributions two variants exist the standard sanderson and modified standard lloyd methods but they are essentially similar we describe an adaption of the lloyd method which involves constructing distribution moment ratio plots contoured in terms of strain ratio and initial standard deviation the relative merits of the two approaches are considered using data from the rivet thrust sheet exposed in the la grave region of the external french alps we find that whereas the fragmentation approach yields relatively simple strain estimates true extensions and a strain ellipse the reorientation approach only provides an estimate of the in plane strain ratio if the exact shape of the belemnite orientation distribution before deformation is known the implications of these results are discussed in terms of local belemnite deformation histories and the evolution of the la grave thrust belt and the alpine orogeny

aqueous sulfur speciation possibly linked to sublimnic volcanic gas water interaction during a quiescent period at yugama crater lake kusatsu shirane volcano central japan after the phreatic eruption in 1982 83 volcanic activities at kusatsu shirane volcano had been decreasing and reached a minimum in 1990 had turned to a temporal rise in activity up to 1994 and then decreased again at least up to 1997 during this low activity period we observed a relatively short 1 y cyclic variation in polythionates ft in the yugama lake water spectral power density analysis of the ft time series by an autoregressive maximum entropy spectral estimation mese method indicates that the major frequency in the ft variations is 1 0 y 1 and the minor is 2 3 y 1 1 0 and 0 3 0 5 y in periodicity respectively annual variations in the lake temperature are ruled out for explaining these periodicities we attribute these cyclic variations to a cyclic magnification reduction in meteoric water injection into a hydrothermal regime where volcanic gases from cooling magma bodies at depth and cooler oxidized groundwater come into contact with each other this interaction may result in a periodical change in the composition and flux of so 2 and h 2 s gases being discharged into the lake and forming ft from a phase deviation 2 3 months in the cycles between the annual precipitation including snowmelt and the ft time series we estimated the maximal depth of a hydrothermal reservoir beneath the lake assuming a vertical hydraulic conductivity 5 10 3 cm s of the volcanic detritus around the summit hydrothermal system chloride in the lake water reached a maximum 1 5 years faster than ft this is most likely due to a gradual elevation of the potentiometric front of a concentrated sublimnic solution in the hydrothermal reservoir variations of dissolved so 2 and h 2 s in the lake water were not consistent with those of the fumarolic gases on the north flank of the volcano this fact together with additional observations strongly suggests that these fumaroles may have the same origin but are chemically modified by a subsurface aquifer the ft monitoring at active crater lakes during a quiescent period can provide insight into the annual expansions and reductions of a volcano hosted hydrothermal reservoir a simple analytical method in the field for the semi quantitative determination of dissolved so 2 and h 2 s in crater lake waters is given in appendix 2

elevated residual layers and their influence on surface boundary layer evolution abstract elevated mixed layers emls are an important factor in the development of springtime thunderstorms over the united states emls can be considered a subset of a larger class called residual layers since the mean state variables are the same at least initially as those of the boundary layers in which emls a formed it is possible however for boundary or residual layers that are not necessarily well mixed to be advected off regions of elevated terrain and overrun boundary layers forming over lower terrain these layers are called elevated residual layers erls erls may form frequently in regions near mountains where terrain gradients exist a simple slab mixed layer model is used to examine how idealized erl potential temperature profiles influence surface boundary layer development in addition several regionally generated erls were observed over phoenix arizona during the southwest area monsoon project these erls appear to have produced a change from moistening to entrainment drying s

analysis of three dimensional strain modified uniform distributions andalusite fabrics from a granite aureole a method of analysing finite strain from an initial random distribution of lines or planes is presented the shape of the strain ellipsoid is mapped to the eigenvalue ratios of an orientation matrix the method is used to interpret the andalusite fabrics from the aureole of the ardara granite county donegal ireland the high flattening strains determined in the aureole are accompanied by oblate strains in the granite margins and support the concept of deformation produced by expansion of the pluton

strain analysis in a cover thrust zone external french alps abstract the la grave thrust zone is situated in the external french alps north of the pelvoux basement massif jurassic cover rocks are deformed and imbricated in a region some 15 km square strains have been measured using the statistical reorientation of belemnites the extension of belemnites and the shapes of pyrite pressure shadows orientation data are treated statistically following sanderson 1977 groups of 100 measurements do not provide very accurate results and generally underestimate the strain when compared with more accurate determinations from extension measurements in addition to providing reliable finite strain markers pyrite pressure shadows allow interpretation of the incremental strain history in the area studied strains accumulated irrotationally in the plane of the bedding the deformed autochthon to the basement massif and the lower thrust sheets were deformed by layer parallel shear and extensional flow which produced ls fabrics with a down dip lineation the higher thrust sheets were deformed by layer parallel shear and compressive flow which produced ls to l fabrics with a strike parallel lineation

precursory changes in fumarolic gas temperature associated with a recent submarine eruption near izu oshima volcano japan significant temperature changes in a steamrich fumarolic gas from a deep hole in the izu oshima volcano japan were observed prior to a series of earthquake swarms and submarine volcanic eruptions which occurred off the eastern coast off the izu peninsula about 40 km ne of the izu oshima volcano in july 1989 we suggest that temperature changes indicate that the izu oshima volcano and the submarine volcanic cone the teishi knoll are linked and that upward movement of teishi magma resulted in a gas pressure decrease of the izu oshima magma this new suggestion of a link between two magma systems over such a large distance may be of great significance for understanding arc volcanism our observation may be of use in the future prediction of volcanic eruptions in the izu area

influence of volcanic eruptions on helium isotope ratios in hydrothermal systems induced by volcanic eruptions temporal variations of 3he4he and 4he20ne ratios occur in high temperature gases from a steam well located about 3 km north of the central cone of mt mihara an active volcano in oshima island japan the 3he4he ratio gradually increased from 1 71ratm 1 71 times the atmospheric ratio of 1 40 10 6 in october 1986 to 5 02 ratm in november 1987 taking into account a similar 4he20ne change the magmatic he component in the steam has increased since the violent eruptions of oshima volcano from november 15 to december 18 1986 this confirms a direct relationship between magmatic activity and elevated 3he4he ratios in groundwater hydrothermal systems based on the distance from the craters to the steam well the time lag between the eruptions and the increase of 3he4he we estimate the magmatic component velocity in the fluid flow the calculated value several tens of m per day is significantly higher than typical groundwater flow in deep sedimentary basins of japan

a study of convection initiation in a mesoscale model using high resolution land surface initial conditions abstract a coupled convection resolving mesoscale atmosphere land surface model lsm is used to investigate land surface planetary boundary layer pbl interactions responsible for the initiation of deep moist convection over the southern great plains of the united states on 19 june 1998 a high resolution land data assimilation system provides initial conditions to the lsm facilitating examination of soil moisture effects on forecasts of deep convection during the late morning and early afternoon the southwestern portion of a simulated southwest northeast sw ne oriented surface water vapor gradient zone evolves into an intense dryline unlike the northeastern portion which remains relatively weak despite these regional differences midafternoon convection initiation occurs within a 100 km wide region of enhanced pbl depth along much of the sw ne extent of the water vapor gradient zone the afternoon pbl depth maximum results from a midmorning to early afternoon surface sensible heat flux maximu

helium isotope variations in turkey relationship to tectonics volcanism and recent seismic activities the distribution of helium isotope ratios in the various tectonic provinces of turkey is examined through a synthesis of previously published data and the results of a recent survey along the north anatolian fault zone nafz following the catastrophic 1999 earthquakes the r ra values where r sample 3he 4he and ra air 3he 4he cover a wide range from 0 05 to 7 87 and the mantle derived helium is clearly identified in most locations the mantle derived component is high 50 of total he in a regions of central and eastern anatolia both of which are associated with historically active volcanoes and b the seismically active west to central segment of nafz while the mantle contribution reaches a maximum at nemrut volcano in eastern anatolia a region of dominantly compressional tectonics and with moderate enthalpy geothermal fields it is relatively low 50 in the western anatolian extensional province even though this region has the highest geothermal potential the average 3he enthalpy ratios estimated for the different provinces suggest lithospheric stretching and rise of the geotherm as the major mechanism of high heat flow yet limited intrusive activity in western anatolia is suggested as the reason for the comparatively low he additions and consequently low 1 7 106 atoms j 3he enthalpy ratios a more extensive magmatic activity appears to be responsible for the greater input of both heat and helium in eastern and central anatolia with intra province 3he enthalpy variations from 3 1 106 atoms j in eastern to 0 25 106 atoms j in central anatolia reflecting the ageing of hydro magmatic systems the relatively high 3he concentrations in low enthalpy waters of northern anatolia 2 8 106 atoms j are particularly significant since there is no evidence of volcanic activity associated with the strike slip motion along the seismically active segment of nafz continuous monitoring of he isotope compositions along nafz should lead to a better understanding of this apparent anomaly as well as the relationship if any between he isotope variations and seismic activities in this region