a new automatic subsurface gas monitoring system for seismogeochemical studies installed in haruno borehole shizuoka prefecture central japan the results of subsurface gas monitoring by application of gas chromatography gc to the gas composition of bubbles associated with groundwater for seismogeochemical studies are reported an automated gas monitoring system was used to determine gas compositions in a 500 m borehole at the haruno crustal movement observation site hos central japan during period 1 from december 1999 to december 2000 the average two standard deviation 2sd compositions of gases in this period were he 82 29 ppmv h2 170 62 ppmv ar 0 05 0 07 n2 50 8 and ch4 45 6 a new automated gas monitoring system equipped with a micro gc was installed in the borehole at the hos and gas bubbles from the borehole were monitored during period 2 from december 2006 to march 2007 the average two standard deviation 2sd compositions of gases in this period were he 8 7 ppmv h2 13 15 ppmv ar 0 6 0 3 n2 66 7 and ch4 14 14 the gas concentration ratios he ar h2 ar n2 ar and ch4 ar fluctuated significantly over time and repeatedly showed abrupt spike like increases during period 2 the gas compositions obtained in period 1 and 2 were markedly different over the period from 2006 to 2007 the gas bubbles were depleted in he h2 and ch4 of deep origin but enriched in ar and n2 of atmospheric origin this difference can be interpreted as being due to an irreversible change of the aquifer gas system the present deep component in the hos gas is estimated to have composition he 63 ppmv h2 37 ppmv ar 0 17 n2 63 and ch4 37 the new monitoring system is able to analyze the gas composition using a smaller volume of sample gas and with greater precision than the previous system during the 3 month monitoring period 2 the separation capacity of the capillary column of the micro gc was sufficiently maintained to determine gas chromatographic peak areas for the five gaseous species examined this study confirms that the new monitoring system with micro gc is promising for continuous subsurface gas monitoring for earthquake prediction studies

preseismic hydrogen gas anomalies caused by stress corrosion process preceding earthquakes simultaneous monitoring of he h2 ar n2 ch4 and rn in gas bubbles of groundwater from the 1 500 m deep nagashima well in the active yoro fault zone central japan reveals that three microearthquakes with m 1 6 2 6 in the fault zone are accompanied and preceded by increases of h2 as is a moderately large event with m 5 4 in the same fault zone all the focal distances of the earthquakes are within 25 km no comparable anomalies were seen in the gas species other than h2 we suggest that the selective and preseimic increases of h2 in groundwater gas bubbles are geochemical signals of the earthquake nucleation process of stress corrosion mechanism aseismic slips preceding earthquakes in the active fault zone are likely to have enhanced h2 production by mechanochemical reaction of fractured rock surface with water in pre existing fault planes as groundwater conduits

extensional tectonics of northwestern macedonia greece since the late miocene tectonic field studies in the florina ptolemais basin northwestern greece were carried out in an attempt to define the regional stress tensors in selected areas affected by neogene and quaternary faulting using recently proposed quantitative methods the analysis allows us to distinguish two extensional phases in the area a late miocene pliocene one with a ne sw average direction of extension and a pleistocene recent one with a nw se direction of extension we conclude that the principal stress axes 2 and 3 were interchanged in passing from one phase to the other these results are reasonably consistent with results of studies carried out in other parts of the aegean area especially the south aegean back arc domain

coseismic changes of subsurface gas compositions disclosed by an improved seismo geochemical system an automatic system for seismo geochemical observation has been improved to monitor small changes in subsurface gas composition this system is computer based and consists of an on site monitoring unit for gas analyses and a telemetry unit for transmitting the observation data to our laboratory the analytical data with this system showed three coseismic anomalies in spring gas compositions at a monitoring station for these 11 months these anomalies were associated with a far and large earthquake or two small and near ones respectively the gas anomaly as a spike like signal appears only for a short period and can be detected on the basis of temporally dense data provided by the new system the result shows that the behavior of subsurface gases is sensitive to crustal movements

origin and coseismic behavior of mineral spring gas at byakko japan studied by automated gas chromatographic analyses abstract the origin and coseismic behavior of mineral spring gas were examined on the basis of continual monitoring data for several gas species the automatic monitoring system used in this study consists of two gas chromatographs and a personal computer several gas species can simultaneously be analyzed with these analyzers the system was so stable and sensitive that minute coseismic anomalies in these species could be detected a positive correlation between n 2 ar and ch 4 ar implies that the mineral spring gas is a mixture of atmospheric air and lithospheric gas the lithospheric gas is mainly composed of n 2 and ch 4 and also contains trace amounts of he it is inferred from isotopic data that lithospheric n 2 and ch 4 are thermogenic and he is mostly radiogenic in contrast o 2 and h 2 in trace amounts show large diurnal fluctuations suggesting that these species should be mostly biogenic ten earthquakes felt around the station occurred during the monitoring period and four of them coincided with coseismic anomalies in the he ar ratio the anomalies may be interpreted as follows by the ground motion at these felt quakes he accumulated in the ground was additionally released into the spring water the continual monitoring of these gas species enables us to discuss in detail the origin and behavior of the spring gas and to evaluate background noise of the data

lacustrine sediments document millennial scale climate variability in northern greece prior to the onset of the northern hemisphere glaciation abstract we investigated two lignite quarries in northern greece for orbital and suborbital climate variability sections lava and vegora are located at the southern and northern boundaries of the ptolemais basin a northwest southeast elongated intramontane basin that contains upper miocene to lower pliocene lacustrine sediments sediments show cyclic alterations of marl rich light and coal rich or clay rich dark strata on a decimeter to meter scale first we established low resolution ground truth stratigraphy based on paleomagnetics and biostratigraphy accordingly the lower 67 m and 65 m that were investigated in both sections vegora and lava respectively belong to the upper miocene and cover a time period of 6 85 to 6 57 and 6 46 to 5 98 ma at sedimentation rates of roughly 14 and 22 cm ka in order to obtain a robust and high resolution chronology we then tuned carbonate minima low l values high magnetic susceptibility values to insolation minima besides the known dominance of orbital precession and eccentricity we detected a robust hemi precessional cycle in most parameters most likely indicative for monsoonal influence on climate moreover the insolation forced time series indicate a number of millennial scale frequencies that are statistically significant with dominant periods of 1 5 8 kyr evolutionary spectral analysis indicates that millennial scale climate variability documented for the ptolemais basin resembles the one that is preserved in ice core records of greenland most cycles show durations of several tens of thousands of years before they diminish or cease this is surprising because the generally argued cause for late quaternary millennial scale variability is associated with the presence of large ice sheets which cannot be the case for the upper miocene possible explanations maybe a direct response to solar forcing an influence on the formation of north atlantic deep water through the outflow of high salinity water or an atmospheric link to the north atlantic oscillation

millennial scale climatic cycles in the early pliocene pollen record of ptolemais northern greece early pliocene lacustrine sediments from the ptolemais basin northern greece exhibit a climatically induced cyclicity which can be correlated with the orbital cycle of precession superimposed on precession controlled cycles palynological time series data reveal a higher order climatic cyclicity with periodicities of 10 2 5 and 1 5 ka these millennial scale vegetation changes are likely to reflect changes of the soil moisture gradient on mountain slopes caused by fluctuations in orographic winter precipitation such fluctuations corroborate the concept of a nao like north atlantic climatic teleconnection during early pliocene times the periodicities are similar to those of climate oscillations inferred from quaternary records the occurrence of millennial scale cyclicity in a time interval when the northern hemisphere was essentially ice free implies an ultimate forcing mechanism that operated independently of changes in the thermohaline circulation in the atlantic ocean the cycles are likely to be related to long period variations in solar activity

biological response to milankovitch forcing during the late albian kirchrode i borehole northwestern germany abstract we studied the biological response to orbital forcing in marine upper albian sediments recovered from the 245 m long kirchrode i borehole in the lower saxony basin in northwestern germany results from quantitative analysis of planktonic and benthic foraminifera of calcareous nannofossils and radiolaria were used for this study spectral analysis in the depth domain indicates for the high sedimentation rate part of the upper albian dominant periods with wavelengths of 10 13 m 5 6 m and 2 3 m which we interpret to represent the biological response to orbital forcing in the milankovitch frequency bands eccentricity obliquity and precession respectively in addition a low amplitude 40 50 m cycle was found which would represent the long term eccentricity variation of roughly 400 ka microfossil cyclicity does not change significantly within the whole core indicating sedimentation rates of 11 12 cm ka on an average with variations between 3 5 and 13 ka microfossils show greater variability in their abundance changes than the physical and chemical parameters and also greater power in the higher frequency bands obliquity and precession while most of the planktonic foraminifer species studied are dominated by variations in the obliquity most benthic foraminifer species show an additional strong influence of precession these differences in the cyclicity of the abundance changes are interpreted as reflecting a stronger influence of low latitude water in the deep waters of the late albian lower saxony basin than in the shallow waters this basin was part of a wide boreal epicontinental sea which was connected to the tethys to the south via the polish strait and via the paris basin and which was connected with the north atlantic and arctic to the north in analogy to results from analysis of data from the late neogene strong effects of precession interpreted as being more characteristic for changes influences triggered in the low latitudes and those of obliquity to be more characteristic for influences from the high latitudes the presence of a relatively strong eccentricity cycle not only in the compound parameters but also in the abundance changes of single species during the late albian means that there must have been a non linear response to orbital forcing and internal feedbacks

final closure of panama and the onset of northern hemisphere glaciation abstract the greenland ice sheet is accepted as a key factor controlling the quaternary glacial scenario however the origin and mechanisms of major arctic glaciation starting at 3 15 ma and culminating at 2 74 ma are still controversial for this phase of intense cooling ravelo et al 1 a c ravelo d h andreasen m lyle a o lyle m w wara regional climate shifts caused by gradual global cooling in the pliocene epoch nature 429 2004 263 267 proposed a complex gradual forcing mechanism in contrast our new submillennial scale paleoceanographic records from the pliocene north atlantic suggest a far more precise timing and forcing for the initiation of northern hemisphere glaciation nhg since it was linked to a 2 3 c surface water warming during warm stages from 2 95 to 2 82 ma these records support previous models g h haug r tiedemann effect of the formation of the isthmus of panama on atlantic ocean thermohaline circulation nature 393 1998 673 676 2 claiming that the final closure of the panama isthmus 3 0 2 5 ma j groeneveld s steph r tiedemann d nurnberg d garbe schonberg the final closure of the central american seaway geology in prep 3 induced an increased poleward salt and heat transport associated strengthening of north atlantic thermohaline circulation and in turn an intensified moisture supply to northern high latitudes resulted in the build up of nhg finally culminating in the great irreversible climate crash at marine isotope stage g6 2 74 ma in summary there was a two step threshold mechanism that marked the onset of nhg with glacial to interglacial cycles quasi persistent until today

leaky slope waves and sea level unusual consequences of the beta effect along western boundaries with bottom topography and dissipation abstractcoastal trapped waves ctws carry the ocean s response to changes in forcing along boundaries and are important mechanisms in the context of coastal sea level and the meridional overturnin

possible solar origin of the 1 470 year glacial climate cycle demonstrated in a coupled model dansgaard oeschger events are rapid climate fluctuations that occurred during and at the end of the last ice age with remarkable regularity there were 23 such events between 110 000 and 23 000 years bp with a periodicity of 1 470 years identify the source of this cycle and it should be possible to say what triggered these events the sun had been excluded as a possible cause because of the lack of a 1 470 year spectral contribution in records of solar variability despite this braun et al present a new hypothesis that convincingly explains the 1 470 year period as the net result of two well known solar cycles the devries and gleissberg cycles with periods of 210 years and 87 years many palaeoclimate records from the north atlantic region show a pattern of rapid climate oscillations the so called dansgaard oeschger events with a quasi periodicity of 1 470 years for the late glacial period1 2 3 4 5 6 various hypotheses have been suggested to explain these rapid temperature shifts including internal oscillations in the climate system and external forcing possibly from the sun7 but whereas pronounced solar cycles of 87 and 210 years are well known8 9 10 11 12 a 1 470 year solar cycle has not been detected8 here we show that an intermediate complexity climate model with glacial climate conditions simulates rapid climate shifts similar to the dansgaard oeschger events with a spacing of 1 470 years when forced by periodic freshwater input into the north atlantic ocean in cycles of 87 and 210 years we attribute the robust 1 470 year response time to the superposition of the two shorter cycles together with strongly nonlinear dynamics and the long characteristic timescale of the thermohaline circulation for holocene conditions similar events do not occur we conclude that the glacial 1 470 year climate cycles could have been triggered by solar forcing despite the absence of a 1 470 year solar cycle

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

gas geochemistry and seismotectonics a review abstract publications on soil and spring gases have been examined regarding their relationships with both tectonic and seismic activities the main sources behaviours and uses of species detected in soils and springs are displayed and their mode of sampling and analysing briefly described the main patterns of degassing in soils are described and we outline the wide range of geochemical signatures as the result of both permeability and mineralogical contrasts because thermomineral waters have been in contact with great volumes of crustal rocks at various depths spring gases might be more representative of the local environment than soil gases moreover gas signature comparisons show that spring gases are much more enriched with deep gases and slightly contaminated by atmospheric gases therefore they can be considered as better samples for identifying precursors of earthquakes environmental perturbations are examined and it is shown from divergent cases that pressure temperature soil moisture or earth tides may generate very high perturbations of the degassing process such effects demonstrate that no systematic correction law can be proposed and that removing external contributions from gas concentrations must be performed case by case this demonstrates therefore the need for the simultaneous measurement of external parameters during gas monitoring a qualitative examination of about 150 claimed precursors proposed in the literature has been reviewed as noted by previous authors anomalies appear at distances sometimes much greater than typical source dimensions and occur in the field of strain higher than 10 9 most of them being in the field of strain higher than 10 8 taking into account the very high heterogeneity of such a set of data we can suggest that amplitudes of gas anomalies are independent of both magnitudes and epicentral distances of related earthquakes suggesting local conditions to control amplitudes on the contrary precursory time and duration of anomalies seem to increase both with magnitudes and epicentral distances abundant evidence demonstrates the major role of crustal fluids in the earthquake cycle many works have outlined the fact that crustal instabilities can appear as the result of low stress strain perturbations during loading it has been suggested that motion of fluids may occur at various scales from microcrack fluid transfer up to changes of hydraulic levels of water tables the study of subsequent anomalies is expected to supply a tool for earthquake prediction following previous authors we outline the need for further methodological improvements including the setting up of multiparameter station networks and the simultaneous recording of the main external parameters atmospheric pressure water and air temperature soil moisture for signal processing

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

the role of low temperature organic matter diagenesis in carbonate precipitation within a marine deposit abstract carbonate minerals in veins can record paleo hydrogeological information that enables the reconstruction of groundwater history this paper investigates the cause of differences in the occurrence of carbonate veins in the koetoi and wakkanai formations both neogene mudstone units in northwestern hokkaido from the perspective of controls on co2 supply from the alteration of organic matter carbonate veins are rare in the koetoi formation but are widespread in the wakkanai formation this area is a region of oil and gas accumulation where deep groundwater is saturated mainly with ch4 and co2 the results show high 13c values in co existing ch4 32 6 and co2 31 0 gases an investigation of 13c d systematics among these gases indicates that isotopic fractionation was caused by microbial co2 reduction although total organic carbon content in the koetoi formation decreases with increasing depth total organic content in the wakkanai formation remains roughly constant with depth furthermore although 13c values also show depth dependence values from the wakkanai formation are higher than those from the koetoi formation this 13c enrichment could be explained by rayleigh fractionation in a closed system based on these results the processes behind the formation of the carbonate veins can be summarized as follows carbon dioxide behavior is thought to play an important role with respect to carbonate formation because co2 abundance is closely linked to ph and pressure in shallow sedimentary rocks such as the koetoi formation that have started to experience diagenetic alteration of organic matter co2 in groundwater is supplied by microbial decomposition of organic matter and is reduced to ch4 by methanogens in deep sedimentary rocks such as the wakkanai formation that have undergone diagenesis but have only experienced moderate temperatures so that thermal decomposition of organic matter has not yet begun microbial degradation of organic matter has proceeded too far for any more co2 to be produced thus carbonate precipitation is initiated when ph rises due to microbial co2 reduction the contrast between the occurrence of carbonate veins in the koetoi and wakkanai formations can be explained by our results which can also be applied to general carbonate behavior in marine sedimentary rocks

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

gas geochemistry applied to earthquake prediction an overview terrestrial gases in groundwater and soil air have been extensively studied in recent years in seismically active areas especially in ussr china japan and united states in search of premonitory changes that might be useful for earthquake prediction concentrations of radon helium hydrogen mercury carbon dioxide and several other volatiles have been found generally to be anomalously high along active faults suggesting that the faults may be paths of least resistance for the terrestrial gases generated or stored in the earth to escape to the atmosphere temporal gas concentration changes with durations of a few hours to many months have been observed before many large earthquakes at a relatively small number of favorably situated stations at epicentral distances of up to several hundreds of kilometers these sensitive stations are generally located along active faults especially at intersections or bends of faults or some other structurally weak zones possibly because of tectonic strain concentration at such places however gas concentrations especially those measured at or near the ground surface may also be significantly affected by meteorological hydrological and other nontectonic changes in the environment the nontectonically induced variations must be carefully eliminated or recognized in the search of true earthquake related anomalies

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

hydrological response to earthquakes in the haibara well central japan i groundwater level changes revealed using state space decomposition of atmospheric pressure rainfall and tidal responses summary for the groundwater level observed at the haibara well shizuoka prefecture central japan time series analysis using state space modelling is applied to extract hydrological anomalies related to earthquakes this method can decompose observed groundwater level time series into five components atmospheric pressure tidal and precipitation responses observation noise and residual water level the decomposed responses to atmospheric pressure and precipitation are independently determined and are consistent with the expected response to surface loading in the groundwater level at the haibara well 28 coseismic changes can be discerned during the period from 1981 april to 1997 december there is a threshold in the relationship between earthquake magnitude and the well hypocentre distance above which earthquakes cause coseismic changes in the residual water level all of the coseismic water level changes at the haibara well are decreases although 33 per cent of the estimated coseismic volumetric strain steps are contraction which would be expected to cause water level increases the coseismic changes in groundwater level are more closely proportional to the estimated ground motion than to coseismic volumetric strain steps suggesting that ground motion due to earthquakes is the major cause of the coseismic water level drops and that the contribution from static strain is rather small possible pre or inter earthquake water level changes have occurred at the haibara well and may have been caused by local aseismic crustal deformation

gas geochemical changes at mineral springs associated with the 1995 southern hyogo earthquake m 7 2 japan abstract gas concentrations monitored at a mineral spring in central japan over the past 15 years showed similar changes before and after two large earthquakes september 1984 m 6 9 50 km distant and january 1995 m 7 2 220 km distant namely a concurrent and abrupt drop in all three gas ratios he ar n 2 ar and ch 4 ar several months before the events improved measurements of gas compositions since 1991 and the addition of gas discharge rate monitoring since 1993 disclosed the following features for anomalies in response to small earthquakes as well as the large 1995 event 1 the gas ratios increased for both large and small earthquakes but they did not return to the preseismic values for the large event as they did within a few hours for the small events 2 at the 1995 event the gas discharge rate decreased remarkably 3 h before the event and then increased to higher than preseismic level for several months in contrast coseismic rates at small events generally increased for less than 15 min 3 during a seismically quiet period from january 1993 to december 1994 the variation in the he ar ratio was well correlated with that of gas discharge rate such correlation disappeared in august and september 1994 when the three gas ratios dropped before the large event 4 gas compositions at an auxiliary monitoring site revealed a coseismic change similar to that described above for the 1995 event these lines of evidence show that subsurface fluids may habitually respond to changes in physical conditions relating to earthquake occurrences and thus suggest the usefulness of monitoring subsurface fluids for earthquake prediction