image log analysis of in situ stress orientation breakout growth and natural geologic structures to 2 5 km depth in central scandinavian caledonides results from the cosc 1 borehole stress induced borehole deformation analysis in the collisional orogeny in the scandinavian caledonide deep scientific borehole establishes in situ stress orientation in a poorly characterized regi

decadal variability in the kuroshio oyashio extension simulated in an eddy resolving ogcm abstract through analysis of a hindcast integration of an eddy resolving quasi global ocean general circulation model decadal variability in the kuroshio oyashio extension region is investigated with particular emphasis on that of the subarctic oyashio and the kuroshio extension ke fronts the ke front is deep and is accompanied by a sharp sea surface height ssh gradient with modest sea surface temperature sst gradient in contrast the subarctic front is shallow and is recognized as a zone of tight gradient in sst but not ssh as a decadal scale change from a warm period around 1970 to a cool period in the mid 1980s those fronts in the model migrate southward as observed and the associated pronounced cooling is confined mainly to those frontal zones reflecting the distinctive vertical structure of the fronts the mixed layer cooling is the strongest along the subarctic front whereas the subsurface cooling and the associated salinity changes are most pronounced along the ke front concomitan

anatomy of north pacific decadal variability abstract a systematic analysis of north pacific decadal variability in a full physics coupled ocean atmosphere model is executed the model is an updated and improved version of the coupled model studied by latif and barnett evidence is sought for determining the details of the mechanism responsible for the enhanced variance of some variables at 20 30 yr timescales the possible mechanisms include a midlatitude gyre ocean atmosphere feedback loop stochastic forcing remote forcing or sampling error decadal variability in the model is expressed most prominently in anomalies of upper ocean streamfunction sea surface temperature sst and latent surface heat flux in the kuroshio oyashio extension koe region off japan the decadal signal off japan is initiated by changes in strength and position of the aleutian low the atmospheric perturbations excite sst anomalies in the central and eastern north pacific with opposing signs and canonical structure the atmospheric perturbations also change the ekm

the signature of oceanic processes in decadal extratropical sst anomalies the relationship between decadal sst and turbulent heat fluxes is assessed and used to identify where oceanic processes play an important role in extratropical decadal sst variability in observational datasets and coupled climate model simulations from the cmip5 archive positive correlations between upward turbulent heat flux and ssts indicate an active role of oceanic processes over regions in the north atlantic northwest pacific southern pacific and southern atlantic the contrasting nature of oceanic influence on decadal sst anomalies in the northwest pacific and north atlantic is identified over the northwest pacific sst anomalies are consistent with changes in the horizontal wind driven gyre circulation on timescales of between 3 7 years in both the observations and models over the north atlantic sst anomalies are also preceded by atmospheric circulation anomalies though the response is stronger at longer timescales peaking at around 20 years in the observations and at around 10 years in the models

stress measurements and tectonic implications for fennoscandia abstract the main results from the fennoscandian rock stress data base frsdb are presented rock stress data from sweden are now being selected to enter the data base of the world stress map project of the international lithosphere programme it is suggested that ridge push from the mid atlantic ridge is the major stress generating mechanism the scatter in stress magnitude and direction for fennoscandia is due to the change in the stress field near faults this is illustrated by means of simple 2 dimensional distinct element analyses of blocky rock masses subjected to a homogeneous far field stress regime earthquakes are assumed to appear at fault intersections where stresses are concentrated

tectonic significance of present day stress relief phenomena in formerly glaciated regions abstract investigations were conducted in several regions of norway with the purpose of detecting and measuring stress relief features and to derive from them valuable information on the shallow crustal stress state stress relief features are induced by blasting and sudden rock unloading in road construction and quarrying operations and are common in norway and probably in other regions of fennoscandia as they are in ne america stress relief at the earth9s surface is diagnostic of anomalously high stress levels at shallow depths in the crust and characterizes the formerly glaciated baltic and canadian precambrian shields the mean orientation of the maximum horizontal compressive stress axis as deduced from the orientation of stress relief features was found to be nw se consistent with north atlantic ridge push forces we show that our determined stress orientations are in excellent agreement with other kinds of stress data as a final step we estimate ridge push force magnitudes from gravity data in the north atlantic region our computations suggest that strong ridge push forces characterize the baltic and canadian shields we conclude from this quantitative analysis and our fieldwork results that present day stress relief in fennoscandia and ne america is mostly triggered by plate scale ridge push forces and not by residual glacial loading stresses

decadal response of the kuroshio extension jet to rossby waves observation and thin jet theory abstractthis study examines interannual to decadal variability of the kuroshio extension ke jet using satellite altimeter observations from 1993 to 2010 the leading empirical orthogonal function eof mode of sea level variability in the ke region represents the meridional shift of the ke jet followed by its strength changes with a few month lag this shift of the ke jet lags atmospheric fluctuations over the eastern north pacific by about three years broad sea level anomalies slas emerge in the eastern north pacific 3 4 years before the upstream ke jet shift and propagate westward along the ke jet axis in the course of the propagation the meridional scale of the slas gradually narrows and their amplitude increases this westward propagation of slas with a speed of about 5 cm s 1 is attributed to the westward propagation of the meridional shift of the jet consistent with the thin jet theory whose importance has been suggested by previous numerical studies in addition the westward propagatin

shifting surface currents in the northern north atlantic ocean 1 analysis of surface drifter tracks in the north atlantic ocean from the time period 1990 to 2007 provides evidence that warm subtropical waters have recently increased their penetration toward the nordic seas prior to 2000 the warm water branches of the north atlantic current fed by the gulf stream turned southeastward in the eastern north atlantic since 2001 these paths have shifted toward the rockall trough through which the most saline north atlantic waters pass to the nordic seas these surface drifters are able to overcome the ekman drift which would force them southward under the westerly winds dominating the subpolar atlantic yet the changes in path cannot be accounted for by changes in ekman drift eddy kinetic energy from satellite altimetry shows increased energy along the shifted drifter pathways across the mid atlantic ridge since 2001 these near surface changes have occurred during continual weakening of the north atlantic subpolar gyre as seen by altimetry they are also consistent with the observed increase in temperature and salinity of the waters flowing northward into the nordic seas these findings suggest the changes in the vertical structure of the northern north atlantic ocean its dynamics and exchanges with the higher latitudes wind stress and its curl changes are discussed as a possible forcing of the changes in the pathways of the subtropical waters

in situ monitoring and 3d geomechanical numerical modelling to evaluate seismic and aseismic rock deformation in response to deep mining abstract in this work we investigated seismic and aseismic rock mass behaviors in response to deep underground mining for this purpose an area under production of the metal mine of garpenberg sweden was instrumented with a geophysical and geotechnical monitoring network in situ monitoring data were analyzed and interpreted considering mining operations and the local geological setting in addition a 3d elasto plastic numerical model was built to better understand the interactions between quasi static stress changes due to mining and the generation of the induced seismicity results of this multiparameter approach show a complex rock mass response we observed two main types of seismic behaviors one local and temporally short directly induced by production the other long lasting over time and remote from excavations being mainly controlled by geological heterogeneities in addition to seismicity we also observed creep like phenomena induced by mining in turn these time dependent strains appear to be a third mechanism driving seismicity all these findings underline the importance of considering both seismic and aseismic deformations when one wants to characterize the rock mass response to mining this significantly enhances our understanding of the phenomena involved as well as their interactions for an improved hazard assessment in deep mining operations

interdecadal variations of the thermohaline circulation in a coupled ocean atmosphere model abstract a fully coupled ocean atmosphere model is shown to have irregular oscillations of the thermohaline circulation in the north atlantic ocean with a time scale of approximately 50 years the irregular oscillation appears to be driven by density anomalies in the sinking region of the thermohaline circulation approximately 52 n to 72 n combined with much smaller density anomalies of opposite sign in the broad rising region the spatial pattern of see surface temperature anomalies associated with this irregular oscillation bears an encouraging resemblance to a pattern of observed interdecadal variability in the north atlantic the anomalies of sea surface temperature induce model surface air temperature anomalies over the northern north atlantic arctic and northwestern europe

in situ stress from breakouts in the danish sector of the north sea abstract borehole breakouts from 26 wells situated in the danish central graben and one well situated in the northwestern section of the ringkobing fyn high have been studied the data provide information on the orientation of the contemporary principal horizontal stresses down to depths of 4 7 km statistics were used to obtain a mean azimuth of breakouts for each well and each individual breakout was weighted by its length data quality of breakouts is assigned according to the world stress map quality ranking scheme the breakout data reveal that s h orientations in the danish central graben are extremely scattered no regional trend in mean s h orientation can be identified as a result of the large standard deviation 77 similar scatterings of s h orientations have been reported from adjacent regions of the north sea the results indicate that the state of stress in the sedimentary cover of the danish central graben is influenced by a local stress generating mechanism rather than platewide stress transmissions mechanisms three units with different states of stress have been identified and found to correspond somewhat with the lithostratigraphic divisions of the post chalk group chalk group and pre chalk group

in situ stress determination from breakouts in the tornquist fan denmark the tornquist fan a fan shaped region in denmark and western baltic is situated in the transition zone between the western and northern european stress provinces breakout data from 20 wells 0 3 3 6 km were analysed the fan can be divided into three stress provinces i the area south of the romo fracture zone is part of the western european stress province and has nnw sse orientation of the maximum horizontal stress ii the sediment cover in the nonvegian danish basin is dominated by ene wsw orientated maximum horizontal stress iii the maximum horizontal stress is sub parallel to the strike of the sorgenfrei tornquist zone deviations from the regional stress field were observed in wells close to faults and salt diapirs in wells south of the sorgenfrei tornquist zone breakout occurrence decreases with increasing age of the stratigraphic units the downhole breakout distribution seems to correlate with lithology and thickness of the sediment layer

the influence of the interdecadal pacific oscillation on temperature and precipitation over the globe the interdecadal pacific oscillation ipo is a 40 60 year quasi oscillation seen mostly in the pacific basin but its impacts on surface temperature t and precipitation p have been found over australia the southwest u s and other regions here a global analysis of ipo s impacts on t and p and its modulation of enso s influence on t and p over the globe is performed using observational and reanalysis data and model simulations since 1920 there are two warm 1924 1944 and 1977 1998 and two cold 1945 1976 and 1999 present ipo phases whose change is associated with abrupt shifts in north pacific sea level pressure slp and contrasting anomaly patterns in t and p and atmospheric circulation over the eastern and western pacific the ipo explains more than half of the interdecadal variations in t and p over many regions such as northeastern australia western canada and northern india significant correlations between the ipo and local p are observed over eastern australia southern africa and the southwest u s the ipo also modulates enso s influence on local t and p over most of these regions t over northern india is positively correlated with nino3 4 enso index during cold ipo phases but the correlation turns negative or insignificant during ipo warm phases over northeastern australia the t versus enso and p versus enso correlations are stronger during the ipo cold phases than during the warm phases the p versus enso correlation over southern africa tends to be negative during ipo warm phases but becomes weaker or insignificant during ipo cold phases the ipo induced p anomalies can be explained by the associated anomaly circulation which is characterized by a high slp center and anti cyclonic flows over the north pacific and negative slp anomalies and increased wind convergence over the indonesia and western pacific region during ipo cold phases these observed influences of the ipo on regional t and p are generally reproduced by an atmospheric model forced by observed sea surface temperatures

recent horizontal stress directions in basement rocks of southern sweden deduced from open microcracks abstract the strike direction of open intragranular microcracks in quartz and feldspar host grains was determined using optical transmission and reflection microscopy on eight oriented samples taken in two study areas in precambrian basement rocks of southern and south central sweden for an area of about 160 km 2 sw of vastervik and two sample locations w of uppsala the vast majority of open microcracks displays a strong preferred nw se strike direction according to the common assumptions that natural cracks in crystalline rocks are predominantly extensional mode i and that open cracks belong to the latest microcrack generation these strike directions should reflect the sub recent main horizontal stress direction h of the recent tectonic stress field this conclusion is supported by corresponding directions known from in situ stress measurements and focal plane solutions in the vicinity of the study areas it is remarkable that even in samples taken close i e a few hundred metres to recently active large scale faults the orientation of microcracks does not deviate from this common direction this may point to slip on already softened faults very local stress reorientations e g m scale or that local stress relief was accomplished by other processes at micro scale e g mechanical twinning in favourably oriented feldspar crystals or slip on grain boundaries

variability of the kuroshio extension jet recirculation gyre and mesoscale eddies on decadal time scales abstract twelve years of sea surface height ssh data from multiple satellite altimeters are used to investigate the low frequency changes and the interconnections of the kuroshio extension ke jet its southern recirculation gyre and their mesoscale eddy field the dominant signal is characterized by the steady weakening of the ke jet recirculation gyre from 1993 to 1996 followed by a gradual strengthening after 1997 during the weakening period of 1993 96 the ke path migrated southward in general and this path migration reversed in direction during the strengthening period of the ke jet and recirculation gyre after 1997 by hindcasting the ssh signals using linear vorticity dynamics it was found that weakening strengthening in the ke jet and recirculation gyre is consistent with westward propagation of negative positive ssh anomalies generating in the eastern north pacific and strengthening during their westward propagation when the ke jet and recirculation gyre were in a weak mode during 19

ongoing tectonic reactivation of the outer carpathians and its impact on the foreland results of borehole breakout measurements in poland abstract the direction of present day maximum horizontal compression shmax tectonic stress was interpreted for 62 wells in poland using the method of borehole breakout analysis of 4 arm and 6 arm dipmeter logs the study area covers complex tectonic junction of the carpathian orogen and its foreland which comprises the east european craton eec divided by the teisseyre tornquist zone ttz from the palaeozoic platform of western poland for this area frequent deviation of the shmax direction from nw se characteristic for the atlantic ridge push has been interpreted in terms of the alcapa tectonic push in the upper silesian segment of the polish outer carpathians poc nne ssw oriented shmax in the accretionary wedge differs significantly from nnw sse shmax in the autochthonous basement the above discrepancy points to uncoupled type of the suture in this segment of the poc in this scenario the alcapa push involves the nappes and is compensated in the top of the basement which is expressed by systematic shmax rotations in the accretionary wedge of the eastern malopolska segment shmax follows the trend perpendicular to the strike of nappes it is in general agreement with nne ssw oriented shmax in the autochthonous basement that also parallels the alcapa push direction similarity in stress orientation between these structural levels implies coupled suture zone in this segment of the poc further to the north alcapa push is transmitted into the foreland plate where it causes n s orientation of shmax as determined for sedimentary cover of the eec within the baltic portion of the eec further shmax rotation towards the intermediate nnw sse position suggests balance between the alcapa push and the ridge push components within the ttz common shmax rotations from n s to nw se indicate structurally controlled accommodation of the alcapa push in the palaeozoic platform of western poland mesozoic complex of the fore sudetic monocline reveals nne ssw directed shmax that differs from nw se oriented shmax in the variscan accretionary wedge here mechanical decoupling along zechstein evaporates is likely presented set of breakout data from poland shows that recent compressive reactivation of the carpathians exerts strong impact on the stress field of the foreland plate at a distance of 700 km from the suture due to this effect the fore carpathian stress domain within the north european stress province can be discriminated

dependence of stress state on the histories of burial erosion mechanical properties pore pressure and faulting abstract most onshore basins have experienced one or more phases of burial and erosion the geomechanical evolution of simplified and idealised fault bounded mudrock basins on crystalline basement subject to burial and erosion cycles is examined numerically the changes in strains and stress state and the displacements including bedding slip which occur with changes of the overlying load are tracked changes of mechanical properties to represent diagenesis are included development of the widely reported high horizontal normal stresses results from the changes of vertical load and does not rely directly on applied horizontal tectonic shortening strains lateral gradients of normal stress associated with faults are described the final basin stress state is related to the magnitudes of the burial and erosion diagenetic or otherwise changes of mechanical properties and pore pressure changes during burial and at depth the magnitudes of the horizontal stress developed for the 1 km and 2 km burial and erosion cycles tested here exceed the magnitude of the vertical stress for a range of depths extending downwards from the surface unless the horizontal stress is reduced at shallow depths by failure during erosion bedding shear instability during erosion around faults and otherwise may influence the response to engineering disturbance

sulphuric and nitric acid concentrations and spikes along a 200 m deep ice core at d 57 terre adelie antarctica

redistribution of recent collision push and ridge push in central europe insights from fem modelling summary 2 d elastic finite element models of the recent stress field of central europe are built to evaluate the loads exerted on the continental boundary and the magnitude of tectonic stresses within the continental part of the plate the models comprise 24 tectonic blocks their stiffness is either constant throughout the model or varies from block to block 16 fault zones and 12 geologically significant boundary segments we have obtained a relatively unique balance of external tectonic forces by 1 careful adjustment of calculated stress directions and regimes to complex pattern of stress from data and 2 by calibration with gravitational potential energy a high level of compression ca 9 10 12 nm 1 exerted to the short ionian side of the adriatic indenter is crucial for the stress field pattern in central europe the adria microplate rotates due to eccentricity between the africa push from the south and the alpine buttress to the north a free boundary of the apennines does not contribute significantly to this motion kinematics of this indenter is controlled by friction on the dinaric suture which in turn is decisive for strain energy distribution between the alpine and the pannonian domains the predicted pronounced extension in the greece aegean segment 2 5 10 12 nm 1 implies active pull transferred from the hellenic subduction zone this extension releases stress in the balkan pannonian region and enables the eastward escape of tectonic blocks in front of advancing adria significant changes of tectonic push trends are found along the black sea caucasus boundary segment and at the european passive margin from the north sea to the arctic ocean differential stresses in central europe are estimated in the range of 10 60 mpa when averaged over the 30 80 km thick mechanically heterogeneous lithosphere the maximum stiffness contrast across the model is predicted to be of one order of magnitude apparent friction coefficients of fault zones differ between the north european part of the plate 0 4 0 7 the pannonian region 0 15 0 25 and the dinaric suture 0 55

the response of the pacific storm track and atmospheric circulation to kuroshio extension variability an index of the kuroshio extension front strength is produced using a maximum covariance analysis between sea surface temperature sst and sea surface height ssh gradient observations and composites of the atmospheric state are presented during its positive and negative phases using reanalysis data 1992 2011 it is found that when the kuroshio extension is less more meandering with a stronger weaker sst front the atmospheric heat transport by transient eddies is increased in the western eastern pacific region consistent with an increase decrease in low level baroclinicity analysis of the eddy mean flow interaction shows that this zonal shift in heat transport forces anomalous barotropic flow in the eastern pacific where blocking frequency is strongly influenced the above relationships cannot be reconciled with the known response of the north pacific storm track to remote forcing from the tropical pacific nor can they be explained by the response of the ocean to atmospheric forcing via surface heat fluxes or winds rather the zonal shift in the storm track highlighted here and the associated changes in the large scale circulation are interpreted as a response to the interannual variability of the kuroshio extension front

moredalen a canyon in the fennoscandian shield and its implication on site selection for radioactive waste disposal in south eastern sweden abstract in south eastern sweden there are a number of canyon like valleys formed in precambrian bedrock composed of granites and vulcanites the canyons called kursu or kursu valleys are generally interpreted to be formed by glaciofluvial erosion they are all located above the highest post glacial shoreline an example of such a valley is moredalen this paper discusses a combined geological and geophysical investigation of moredalen with the aim to investigate possible reasons for the formation of such an unusual feature moredalen is a marked approximately 7 km long e w striking valley that cuts through a plateau c 140 m a s l coinciding with a late precambrian peneplain geomorphological features of this kind indicate certain characteristics of the bedrock that need to be considered during safety analysis of repositories for nuclear waste the distinct weakness zones along which the kursu valleys are formed create prominent transport paths for groundwater flows furthermore the zones may be potential hazards from a rock mechanical point of view this is emphasized by palaeozoic to mesozoic differential block faulting on both sides of the moredalen valley and neotectonic movements along the valley

predicting western north pacific ocean climate abstract it is shown that wintertime sea surface temperature anomalies in the confluence region of the kuroshio oyashio currents in the western north pacific can be skillfully predicted at lead times of up to 3 yr the predictions are based on the history of the wind stress over the north pacific and oceanic rossby wave dynamics the predictions may be exploitable in fisheries research and other ecological applications

growth of exfoliation joints and near surface stress orientations inferred from fractographic markings observed in the upper aar valley swiss alps abstract granitic rock mass of the upper aar valley grimsel area switzerland contains distinct generations of exfoliation joints which formed during different stages of the pleistocene subparallel to distinct glacial valley palaeotopography the bulk of exfoliation joints shows prominent common fractographic features 1 radial plumose structures with distinct plume axes 2 arrest marks superimposed by plumose striations and 3 gradually developing en echelon fringe cracks multiple arrest marks reveal that exfoliation joints formed incrementally and together with the absence of hackle fringes suggest stable i e subcritical fracturing conditions smooth transitions from plumose structures on the parent plane to en echelon fringe cracks combined with non systematic stepping senses of fringe cracks suggest local vs temporal stress field variations assuming that plume axes formed parallel to the maximum principal compressive stress 1 enables us to infer near surface palaeostress orientations and compare them with classical borehole based in situ stress data the majority of plume axes suggest 1 persistently subhorizontal to slightly inclined 1 orientations at trough valley slopes and 2 near surface variability of 1 orientations originating from topographic perturbation caused by glacial valley erosion superimposed on the regional stress field our investigations of fracture surface morphologies yield unique insights into exfoliation fracture formation such as directional trends of fracture propagation and associated palaeostress orientations within alpine valley slopes

north pacific decadal variability in the community climate system model version 2 abstract north pacific decadal oceanic and atmospheric variability is examined from a 650 yr control integration of the community climate system model version 2 the dominant pattern of winter sea surface temperature sst variability is similar to the observed pacific decadal oscillation with maximum amplitude along the kuroshio extension sst anomalies in this region exhibit significant spectral peaks at approximately 16 and 40 yr lateral geostrophic heat flux divergence caused by a meridional shift of the kuroshio extension forced by basin scale wind stress curl anomalies 3 5 yr earlier is responsible for the decadal sst variability local surface heat flux and ekman heat flux divergence act as a damping and positive feedback respectively a simple linear rossby wave model is invoked to explicitly demonstrate the link between the wind stress curl forcing and decadal variability in the kuroshio extension the rossby wave model not only successfully reproduces the two decadal spectral peaks but a

stress inversion and basement cover stress transmission across weak layers in the paris basin france we investigate the source of non purely gravitational horizontal stresses in the paris basin a nowadays tectonically quiet intracratonic basin in its eastern border of which outstandingly dense stress measurements are available based on a synthesis of published data the stress state in the basin is first shown to be very close to the one that may be extrapolated for the underlying basement in terms of principal stress orientations and horizontal to vertical stress ratios this is in favour of a mechanical coupling between the basement and its sedimentary cover which may seem contradictory to the presence of several weak rock layers in the basin fill e g an argillite layer that was shown to bear low deviatoric stresses and salt layers that are implicated in a major decollement elsewhere to unravel this apparent contradiction a 3d numerical modelling is performed following a rigorous inverse problem approach to determine the long term elastic properties of both the basement and the basin rocks the objective is to find the set of elastic constants that provides the best fit between the calculated stress state in the basin and the in situ data by assuming that the stress state in the basement is known this methodology provides a realistic set of mechanical parameters in agreement with previous studies which leads to the conclusion that the horizontal stresses in the basin constitute its mechanical response to the stresses that developed in the underlying basement during and since the last tectonic event alpine phase the fact that horizontal stresses could be transmitted across the weak horizons contrary to what may be expected at first glance is explained both by the geometry of the basin and the fact that over the long term the stiffnesses of the various sedimentary rocks are only slightly different from each other

a tripole index for the interdecadal pacific oscillation a new index is developed for the interdecadal pacific oscillation termed the ipo tripole index tpi the ipo is associated with a distinct tripole pattern of sea surface temperature anomalies ssta with three large centres of action and variations on decadal timescales evident in the second principal component pc of low pass filtered global sst the new index is based on the difference between the ssta averaged over the central equatorial pacific and the average of the ssta in the northwest and southwest pacific the tpi is an easily calculated non pc based index for tracking decadal sst variability associated with the ipo the tpi time series bears a close resemblance to previously published pc based indices and has the advantages of being simpler to compute and more consistent with indices used to track the el nino southern oscillation enso such as nino 3 4 the tpi also provides a simple metric in physical units of c for evaluating decadal and interdecadal variability of sst fields in a straightforward manner and can be used to evaluate the skill of dynamical decadal prediction systems composites of sst and mean sea level pressure anomalies reveal that the ipo has maintained a broadly stable structure across the seven most recent positive and negative epochs that occurred during 1870 2013 the tpi is shown to be a robust and stable representation of the ipo phenomenon in instrumental records with relatively more variance in decadal than shorter timescales compared to nino 3 4 due to the explicit inclusion of off equatorial sst variability associated with the ipo