late eocene granites in the central sakhalin island russian far east and its implication for evolution of the sakhalin hokkaido orogenic belt abstract the sakhalin hokkaido orogenic belt along the western margin of the okhotsk sea is an important early cenozoic accretionary orogen related to subduction of the paleo pacific oceanic plate in order to study the eocene evolution of this accretionary orogen and related magmatism we carried out zircon u pb dating whole rock elemental and sr nd isotopic analyses on the langeri and val za granitic plutons that intruded the east sakhalin accretionary complex in the central sakhalin island zircon u pb dating results revealed that the langeri and val za plutons were emplaced in the late eocene at 38 36 ma whole rock elemental data indicate that granitoids are mainly peraluminous s type with subordinate i type granites and all granitic samples show arc like geochemical affinity whole rock sr nd isotopic results show consistent low initial 87sr 86sr ratios 0 7042 to 0 7049 positive end t values 1 7 to 3 1 and young nd two stage model ages 611 to 717 ma elemental and isotopic data reveal that granitic rocks of the langeri and val za plutons were generated from remelting of metasediments and amphibolites in the accretionary complex from comprehensive analyses of regional tectonics we concluded that the late eocene granitic rocks were generated in a syn collisional tectonic setting marking the timing for formation of the sakhalin hokkaido orogenic belt the middle late eocene welding of the okhotsk sea plate and the eurasia plate is the most plausible mechanism that caused crustal thickening beneath the sakhalin island and anatexis of metasediments and oceanic crustal materials in the lower crust might be responsible for the formation of late eocene granitic rocks considering the eocene tectonic events in ne asia late paleocene to early eocene subduction of the kula pacific ridge beneath the hokkaido island and eocene initial rift of pull apart basins along strike slip fault system in the hokkaido and sakhalin islands may also contribute to the emplacement of eocene magmatism in the sakhalin hokkaido orogenic belt

upper cretaceous paleomagnetic data from shikotan island kuril arc implications for plate kinematics abstract maastrichtian tuffaceous sandstones and siltstones were sampled from four sites in the northern part of shikotan island in the lesser kuril islands a characteristic component chrm isolated from most samples passes the reversal and fold tests and is most probably a primary remanence the chrm mean direction d 334 i 56 k 36 95 3 2 is 14 3 5 steeper than the pacific reference direction and 13 4 more gentle than the eurasian reference direction we assume that the lesser kuril islands together with their southwestern extension into the nemuro peninsula hokkaido were originally an island arc situated at about 36 n in the central west pacific soon afterwards probably by the end of the late cretaceous the nemuro shikotan island arc became inactive and started moving with the pacific plate in the miocene about 15 m y ago the nemuro shikotan island arc collided with the eurasian plate overrode the subduction zone and occupied its present day position on the pacific side of the kuril island arc although this scenario fits the available paleomagnetic data and kinematics of the pacific plate itself it disagrees somewhat with the kinematic models for the north pacific as a whole in particular by the end of the late cretaceous the northern margin of the pacific plate together with the extinct nemuro shikotan island arc should have been in an area close to the transform or ridge type kula pacific boundary the available paleomagnetic data from northeast asia however indicate that active islands arcs existed in mid northern latitudes of the modern pacific ocean in the cretaceous

the hidaka shear zone hokkaido japan genesis during a right lateral strike slip movement the mesozoic structure of hokkaido which is characterized by a wide spread ophiolite sequence unconformably overlain by a cretaceous flysch sequence is cut by a north south trending metamorphic belt the hidaka belt this contribution aims to demonstrate that the hidaka belt is a wide right lateral strike slip shear zone the movement is contemporaneous with the metamorphism and the magmatism of oligo miocene time

mode of mixture of oceanic fragments and terrigenous trench fill in an accretionary complex example from southern sakhalin abstract four modes of mixture of oceanic materials such as cherts limestones and basalts and terrigenous trench fill sediments are recognized in the cretaceous accretionary complexes in southern sakhalin far eastern pacific margin of the u s s r the first mode is a thin skinned stacking of pelagic bedded cherts with black shale due to duplex formation in association with shallow underplating or off scraping the second mode is a mixture of the uppermost part of the oceanic crust with terrigenous trench fill sediments due to olistostrome formation reconstruction of the original sequence in ascending order suggests that the basement is pillow basalt with overlying pelagic sediments of chert and limestone olistostrome caused by collapse of oceanic crust due to its bending before encountering a trench and finally trenchfill sediments of turbidite this sequence is imbricated by thrusting which appears to have occurred at the time of underplating the third mode is a tectonic mixing of oceanic fragments and terrigenous sediments due to shear which is related to underthrusting of the oceanic plate a reduction in the supply of trench fill sediments causes copious accretion of the upper part of oceanic crust the fourth mode is in situ basalt volcanism at the trench where thick baked margins of terrigenous shale are formed around the injected basalts this mode appears to represent a ridge trench encounter these four different modes of mixing seem to be usual in ancient accretionary complexes in orogenic belts

zonal jet structure and the leading mode of variability an observational analysis of the northern hemisphere circulation during winter reveals that the leading mode of variability depends on longitude in particular the first eof of the zonal mean circulation differs over the atlantic and pacific sectors these results provide motivation for a series of model runs where a simple gcm is used to investigate the effects of the zonal jet structure on the leading mode of variability in the northern hemisphere model results indicate that the leading mode of variability depends on the distance between the eddy driven and subtropical jets when the jets are well separated the leading mode of variability describes latitudinal shifting of the eddy driven jet however when the two jets are nearly collocated pulsing of the combined jet dominates the variability this change coincides with a weakening of the positive feedback between the eddies and zonal flow anomalies these results provide a possible explanation for the reduced amplitude of the northern annular mode in the pacific sector relative to that in the atlantic sector during northern hemisphere winter

on the zonal structure of the north atlantic oscillation and annular modes abstract the zonal structure and dynamics of the dipolar patterns of intraseasonal variability in the extratropical atmosphere namely the north atlantic oscillation nao and the so called annular modes of variability are investigated in an idealized general circulation model particular attention is focused on the relationships linking the zonal structure of the stationary waves synoptic variability i e the storm tracks and the zonal structure of the patterns of intraseasonal variability large scale topography and diabatic anomalies are introduced to modify and concentrate the synoptic variability establishing a recipe for a localized storm track comparison of the large scale forcing synoptic variability and patterns of intraseasonal variability suggests a nonlinear relationship between the large scale forcing and the variability it is found that localized nao like patterns arise from the confluence of topographic and diabatic forcing and that the patterns are more localized than one would e

plate motions in the north pacific the 43 ma nonevent the hawaiian emperor seamount chain in the north pacific ocean is commonly considered to have been produced by motion of the pacific plate over a hotspot if the hotspot is assumed to have remained fixed in a mantle frame of reference the 60 change in trend between the hawaiian and emperor portions of the chain results from a change in motion direction of the pacific plate relative to the mantle at 43 ma during middle eocene time such a large and abrupt direction change should result in significant plate reorganizations and tectonic events in the pacific and surrounding plates but no evidence for these events can be found in addition in this paper it is shown that there were no changes in relative plate motions between pacific area plates that can be associated with the hawaiian emperor bend this is done by calculating motion of the pacific farallon and kula plates relative to asia and north america using the plate circuit farallon pacific antarctica africa north america asia with no major regional tectonic event at the time of the bend it is suggested that there was no plate reorganization at 43 ma and that the emperor portion of the seamount chain was formed by a nonstationary hotspot

integrated multi temporal analysis of the displacement behaviour and morphology of a deep seated compound landslide cerentino switzerland abstract deep seated gravitational slope deformations dsgsds are complex slope instabilities commonly involving long term evolution with significant spatial and temporal variations in slope kinematics the cerentino compound landslide in southern switzerland exemplifies the long term evolution of dsgsds as well as short term movements causing substantial damage to infrastructure using an integrated analysis of surface geomorphology displacement monitoring data borehole core and cosmogenic nuclide dating we discuss the preconditioning and driving factors kinematic behaviour and long term evolution of the instability we demonstrate that foliation orientation and lithological boundaries together with slope geometry and alpine faults likely played significant roles in preconditioning the slope for failure based on morphology mapping and hierarchical clustering analysis of 2007 2018 detrended surface displacement data we show that the landslide is separated into up to eight compartments at surface revealing differences in kinematic behaviour from very active at the toe to insignificant movements in the upper region of the landslide above the village of cerentino these surficial compartments likely correspond to secondary sliding zones within the landslide mass the analysis of data from inclinometer and fibre optic strain sensors installed in a new deep borehole 230 m provided insight into movement within the landslide mass results show vertical heterogeneity in total displacement which appears to be controlled by an active discrete shear zone located at 107 m by shallower secondary sliding surfaces and by distributed movement particularly in the upper 20 m of the instability extrapolation of cosmogenic nuclide dating results from five samples taken on the exposed upper sliding scar reveals a possible age of failure initiation of 5 6 ka with long term decelerating movement trends these generally slow averaged movements show multi annual responses to long term changes in precipitation and locally rapid responses to strong recharge events the rare combination of dating and detailed analysis of displacement allows us to demonstrate the behaviour of dsgsds at long and short timescales with implications for hazard assessment and mitigation of these complex failures

asymmetry in the response of central eurasian winter temperature to amo the asymmetry in the teleconnection of the central eurasian winter surface air temperature sat with the atlantic multidecadal oscillation amo is discussed using observations and model simulations observations indicate that the winter sat over central eurasia 30 70 e 30 50 n shows significant positive anomalies during the warm amo period but weak and insignificant anomalies in the cold amo period in general the warm winters in central eurasia are associated with large scale negative sea level pressure anomalies in europe anomalous southwesterly winds at 850 hpa over europe the geopotential height anomalies at 500 hpa in the south of greenland northern europe western asia and the slant north south pattern jet stream anomalies at 200 hpa in the north and south of the caspian sea reverse patterns occur during cold winters these statistically significant features are observed in the warm phase of amo reversed circulation anomalies are observed during the cold phase of amo however these anomalies are weak and not statistically significant furthermore the asymmetry in the atmospheric response to amo is well supported by simulations with a suite of gfdl atmospheric model idealized experiments and four cmip5 models historical experiments both observations and simulations indicate that rossby waves propagating from the north atlantic eastward to eurasia emerge in the warm amo and disappear in the cold amo thus the different propagations of rossby waves induced by the different surface thermal conditions of the warm and cold amo are the potential connection between the north atlantic ocean and central eurasian climate and may explain the asymmetry

a stochastic model for the spatial structure of annular patterns of variability and the north atlantic oscillation abstract meridional dipoles of zonal wind and geopotential height are found extensively in empirical orthogonal function eof analysis and single point correlation maps of observations and models notable examples are the north atlantic oscillation and the so called annular modes or the arctic oscillation minimal stochastic models are developed to explain the origin of such structure in particular highly idealized analytic purely stochastic models of the barotropic zonally averaged zonal wind and of the zonally averaged surface pressure are constructed and it is found that the meridional dipole pattern is a natural consequence of the conservation of zonal momentum and mass by fluid motions extension of the one dimensional zonal wind model to two dimensional flow illustrates the manner in which a local meridional dipole structure may become zonally elongated in eof analysis producing a zonally uniform eof even when the dynamics is not particularly zonally coherent on hemispheric length scales

dynamics of synoptic eddy and low frequency flow interaction part i a linear closure abstract the interaction between synoptic eddy and low frequency flow self has been recognized for decades to play an important role in the dynamics of the low frequency variability of the atmospheric circulation in this three part study a linear framework with a stochastic basic flow capturing both the climatological mean flow and climatological measures of the synoptic eddy flow is proposed based on this linear framework a set of linear dynamic equations is derived for the ensemble mean eddy forcing that is generated by anomalous time mean flows by assuming that such dynamically determined eddy forcing anomalies approximately represent the time mean anomalies of the synoptic eddy forcing and by using a quasi equilibrium approximation an analytical nonlocal dynamical closure is obtained for the two way self feedback this linear closure directly relating time mean anomalies of the synoptic eddy forcing to the anomalous time mean flow becomes an internal part of a new linear dynamic system for an

evolution of the sakhalin fold system abstract the island of sakhalin is subdivided into two late cretaceous isopic zones the miogeosynclinal western zone and the eugeosynclinal eastern zone the boundary between these zones is marked by a band of greenschists and blueschists melange and olistostrome a thick triassic lower cretaceous formation composed of siliceous volcanogenic deposits with lenses of limestones and interlayers of tuff aleurolites clay shales and siliceous argillaceous shales occurs at the base of a miogeosynclinal upper cretaceous section the upper cretaceous deposits of this zone have a cyclic structure and are represented by terrigenous marine near shore and continental formations the paleogene neogene deposits occur on the upper cretaceous ones with a sharp erosion a lithological complex composing the eastern sakhalin eugeosynclinal zone is represented by alternations of deep water sandy aleurolite clay shale formations including olistostromal horizons with siliceous volcanogenic formations the eugeosynclinal regime remained the same up to the late cretaceous the paleogene neogene deposits occur on the cretaceous ones with a sharp structural unconformity the ophiolite blueschist belt of central sakhalin is compared with the kamuikotan belt in hokkaido the belts of granitoid magmatism and calc alkaline volcanism are nearly parallel to the cretaceous and senonian early paleogene ophiolite blueschist belts of sakhalin an eastward migration of these belts to the pacific is observed the formation stage of the mezosoic deep thrusts effecting distribution of the ophiolitic belts has been changed by the formation stage of the cenozoic wrench fault zones

intraseasonal modulation of the north pacific storm track by tropical convection in boreal winter abstract the modulation of the north pacific storm track by tropical convection on intraseasonal time scales 30 90 days in boreal winter december march is investigated using the ncep ncar reanalysis and noaa satellite outgoing longwave radiation olr data multivariate empirical orthogonal function meof analysis and case compositing based upon the principal components pcs of the eofs reveal substantial changes in the structure and intensity of the pacific storm track quantified by vertically 925 200 mb averaged synoptic eddy kinetic energy seke during the course of a typical madden julian oscillation mjo event the storm track response is characterized by an amplitude varying dipole propagating northeastward as the center of the anomalous tropical convection moves eastward across the eastern indian ocean and the western central pacific a diagnosis of the seke budget indicates that the storm track anomaly is induced primarily by changes in the convergence of energy flux baroclinic conversi

determination of residual strength parameters of jointed rock masses using the gsi system abstract the geological strength index gsi system proposed in 1995 is now widely used for the estimation of the rock mass strength and the rock mass deformation parameters the gsi system concentrates on the description of two factors rock structure and block surface conditions the guidelines given by the gsi system are for the estimation of the peak strength parameters of jointed rock masses there are no guidelines given by the gsi or by any other system for the estimation of the rock mass residual strength that yield consistent results in this paper a method is proposed to extend the gsi system for the estimation of a rock mass s residual strength it is proposed to adjust the peak gsi to the residual gsir value based on the two major controlling factors in the gsi system the residual block volume v b r and the residual joint condition factor j c r methods to estimate the residual block volume and joint condition factor are presented the proposed method for the estimation of rock mass s residual strength is validated using in situ block shear test data from three large scale cavern construction sites and data from a back analysis of rock slopes the estimated residual strengths calculated using the reduced residual gsir value are found to be in good agreement with field test or back analyzed data

error analysis for the determination of tectonic rotation from paleomagnetic data appendix b is available with entire article on microfiche order from american geophysical union 2000 florida avenue n w washington d c 20009 document b83 001 2 50 payment must accompany order recent determinations of tectonic rotation and flattening from paleomagnetic data have exaggerated the size of the confidence limits or error bars by about 25 this has been caused by the misuse of conventional error propagation formulas to derive one degree of freedom error bars from a two dimensional cone of confidence 95 an analytical calculation which is valid when error bars are small shows that the correct error bars are 75 to 80 of the values derived in previous studies i have used numerical integration to check on the applicability of the analytical solution and to calculate error bars when the analytical approximation cannot be used the analytical approximation may be used whenever 95 is less than 10 and the mean inclination is not too close to vertical confidence limits given for tectonic rotation and flattening in recent literature are too large and should be reduced by 20 25 narrowing the error bars in this way permits a more accurate interpretation of paleomagnetic data

climatology of anticyclonic and cyclonic rossby wave breaking on the dynamical tropopause in the southern hemisphere abstract the characteristics of the climatological distribution of the anticyclonic lc1 and cyclonic lc2 rossby wave breaking rwb in the southern hemisphere sh are investigated by calculating the occurrence frequency of the lc1 and lc2 like stratospheric potential vorticity pv streamers in the sh during the austral summer december february djf and wintertime june august jja on several isentropic surfaces by using the 40 yr european centre for medium range weather forecasts ecmwf re analysis era 40 daily dataset the results show that 1 on the equatorward flank of the climatological midlatitude jet mlj the lc1 like pv streamers are frequently found over the central oceanic regions whereas the lc2 like pv streamers are almost absent on the poleward flank of the climatological mlj both types of pv streamers are frequently observed and the lc2 like pv streamers predominate 2 the regions where the occurrences of the pv streamers are frequent overlap the weak zonal wind regions

are the pacific and indo atlantic hotspots fixed testing the plate circuit through antarctica it is often assumed that hotspots are fixed relative to one another and thus constitute a global reference frame for measuring absolute plate motions and true polar wander but it has long been known that the best documented hotspot track the hawaiian emperor chain is inconsistent with the internally coherent tracks left by the indo atlantic hotspots this inconsistency is due either to unquantified motions within the plate circuit linking the pacific with other plates for example between east and west antarctica or relative motion between the hawaiian emperor and indo atlantic hotspots analysis of recent paleomagnetic results from marie byrd land in west antarctica confirms that there has been post 100 ma motion between west antarctica marie byrd land and east antarctica however incorporation of this motion into the plate circuit does not account for the cenozoic hotspot discrepancy comparison of an updated inventory of pacific and non pacific paleomagnetic data does not show a significant systematic discrepancy which along with other observations indicates that missing plate boundaries and other errors in the plate circuit play a relatively small role in the hotspot inconsistency we conclude that most of the apparent motion between the hawaiian emperor and indo atlantic hotspots is real the best estimate average drift rate between these sets of hotspots is approximately 25 mm yr since 65 ma ignoring errors in the plate circuit and a small contribution from cenozoic motions between east and west antarctica 1999 elsevier science b v all rights reserved

the basic ingredients of the north atlantic storm track part ii sea surface temperatures abstractthe impact of north atlantic sst patterns on the storm track is investigated using a hierarchy of gcm simulations using idealized aquaplanet and semirealistic boundary conditions in the atmospheric component hadam3 of the third climate configuration of the met office unified model hadcm3 this framework enables the mechanisms determining the tropospheric response to north atlantic sst patterns to be examined both in isolation and in combination with continental scale landmasses and orography in isolation a gulf stream sst pattern acts to strengthen the downstream storm track while a north atlantic drift sst pattern weakens it these changes are consistent with changes in the extratropical sst gradient and near surface baroclinicity and each storm track response is associated with a consistent change in the tropospheric jet structure locally enhanced near surface horizontal wind convergence is found over the warm side of strengthened sst gradients associated with ascending air and i

using magnetic anisotropy to correct for paleomagnetic inclination shallowing in some magnetite bearing deep sea turbidites and limestones abstract in sediments remanence inclination i may be shallower than the inclination ih of the earth s field in which they were deposited use of magnetic anisotropy to correct for this paleomagnetic inclination shallowing is tested for quaternary turbidite muds from the scotian rise and for cretaceous pelagic limestones from the pacific plate both are dominated by pseudo single domain magnetite carrying a stable remanence whose inclination i determined by stepwise alternating field demagnetization is shallower than ih by an average of 12 for the turbidites and 17 for the limestones anhysteretic remanence arm applied identically to various axes is weakest armmin perpendicular to bedding and strongest armmax parallel to bedding with little anisotropy in the bedding plane and arm min arm max averaging 0 84 for the turbidites and 0 87 for the limestones magnetite also dominates susceptibility with minimum kmin and maximum kmax susceptibility axes perpendicular and parallel to bedding respectively and with k min k max averaging 0 91 for the turbidites and 0 95 for the limestones in theory we expect to find a correlation between tan i and arm min arm max for a suite of specimens with the correlation line s prediction of tan i when arm min arm max 1 yielding an ih estimate corrected for inclination shallowing this correction method is also expected to succeed if arm min arm max is replaced by k min k max provided susceptibility is dominated by multidomain or pseudo single domain magnetite in practice both anisotropies do succeed in correcting for inclination shallowing in three of the four turbidite cores both anisotropies would also likely succeed for the limestones if there were enough samples at any one site since correlating tan i tan i h in place of tan i for the five sites combined predicts tan i tan i h 1 when arm min arm max 1 or k min k max 1 hence we recommend routinely measuring anisotropy in paleomagnetic studies of magnetite bearing sediments and looking for a correlation between tan i and arm min arm max or k min k max remanence anisotropy is more laborious to measure but provides the more reliable estimate of inclination shallowing in cases where no significant correlation is found remanence anisotropy of the magnetite particles in the sediment may also have to be measured to correct for inclination shallowing

geodynamic implications of paleomagnetic data from tertiary sediments in sakhalin russia nw pacific 1 n s trending right lateral strike slip faults which were active in the tertiary transect sakhalin russia while mesozoic forearc and accretionary rocks testify to an earlier period of subduction several kinematic models have been proposed for the region but the details required to constrain these models such as the timing of the transition from subduction to strike slip tectonics in sakhalin are still unknown even first order tectonic features such as the boundaries of the plates with which sakhalin evolved during the tertiary are poorly known paleomagnetic results from around sakhalin were obtained to constrain the geodynamic evolution of the region comparison of paleomagnetic inclination data with the apparent polar wander paths for the eurasian pacific and north american plates suggests that sakhalin probably evolved with the north american plate although a history including the eurasian plate cannot be ruled out paleomagnetic declination data suggest that significant clockwise vertical axis rotation has occurred in sakhalin since the mid paleocene it is likely that this rotational deformation was accommodated by tertiary activity on right lateral strike slip faults which may be associated with the opening of the japan sea tatar strait and kuril basin these data contradict a published kinematic model for eastern sakhalin where counterclockwise vertical axis rotations were predicted for neogene basins in the east sakhalin mountains agreement is better however with published paleomagnetic data from southern sakhalin where clockwise vertical axis rotations were documented

igneous petrogenesis of the yakuno ophiolite japan in the context of the diversity of ophiolites an ophiolite complex includes three major members basaltic volcanics mafic ultramafic cumulates and residual peridotite from the aspect of igneous petrology three distinct types are recognized among the associations of the three members liguria type alkalic basalt plagioclase type cumulates and lherzolite yakuno type high alumina tholeiite clinopyroxene type cumulates and clinopyroxene bearing harzburgite papua type low alumina tholeiite orthopyroxene type cumulates and clinopyroxene free harzburgite in the light of recent experimental studies the three types represent cogenetic complementary products of low 30 degrees of partial melting in the lherzolitic source mantle respectively the cumulates of the yakuno ophiolite show structural and chemical continuity to the underlying residual peridotite and were recrystallized at high pressures 5 10 kb they originated in a deep soft floored magma chamber directly overlying the partially melted residual harzburgite from which the magma was extracted the three members of the yakuno ophiolite were cogenetically formed through a magmatic event induced by a moderate degree of partial melting in the mantle

simultaneous atlantic pacific blocking and the northern annular mode a synoptic situation termed high latitude blocking hlb is shown to occur frequently in both the atlantic and pacific sectors and to result in flow anomalies very similar to those associated with the negative phase of the northern annular mode nam in the respective sector there is a weak but significant link between the occurrence of hlb in the two sectors with atlantic hlb tending to lead pacific hlb by 1 3 days this link arises from rare events in which both sectors are almost simultaneously affected by a large scale wave breaking event which distorts the polar trough over northern canada in several cases the tropospheric wave breaking occurs in tandem with a large scale disturbance of the stratospheric polar vortex there is therefore a physical link between the atlantic and pacific sectors but analysis suggests that this does not contribute to determining the pattern of the nam as conventionally defined from monthly mean data however an alternative version of the nam derived directly from daily data does appear to reflect this physical link these conflicting results highlight the sensitivity of the nam to the period over which data are averaged copyright c 2008 royal meteorological society

paleomagnetism of mid cretaceous red beds in west central kyushu island southwest japan paleoposition of cretaceous sedimentary basins along the eastern margin of asia abstract a paleomagnetic study was carried out on the mid cretaceous sedimentary strata in west central kyushu island southwest japan to elucidate the origin of sedimentary basins along the asian continental margin in the cretaceous we collected paleomagnetic samples from a total of 34 sites of the mid cretaceous goshonoura group shallow marine clastic deposits in west central kyushu and characteristic remanent magnetizations were recognized from 18 horizons of red beds thermal demagnetization has revealed that the red beds contain three magnetization components with low

late cretaceous paleomagnetic data from the median range of kamchatka russia tectonic implications abstract a late cretaceous island arc complex was sampled for paleomagnetic study in the northern part of the median range of kamchatka in most samples thermal demagnetization in 12 18 steps revealed either a reversed characteristic remanent magnetization chrm or a remagnetization circle combining these yielded a positive fold test k s k g 5 8 and we interpreted the chrm to be primary the tilt corrected overall mean direction of dec 105 5 inc 67 0 95 4 1 for these rocks corresponds to a paleolatitude of 49 7 5 6 n this value is 20 to 22 lower than the late cretaceous north american reference values and northward transport of the subject tectonostratigraphic terrane and island arc to which it had originally belonged is strongly indicated the observed paleolatitudes are approximately similar for all late cretaceous island arc complexes in kamchatka and the southern part of the koryak highlands we conclude that these complexes were originally part of the same island arc which originated 20 to 25 south of the continental margin in the campanian and then was transported northward until its emplacement in the paleocene northward drift of the island arc coincided with its activity and the related subduction zone also had to drift with a rapidly moving oceanic plate most probably the kula plate this relationship implies that the subduction zone dipped southward and was consuming oceanic lithosphere presumably the oceanic periphery of the north american plate

underplated units in an accretionary complex melange of the shimanto belt of eastern shikoku southwest japan imbricated thrust stacks composed of melange and oceanic slabs occur in the shimanto belt eastern shikoku sw japan the melanges are divided into two types melange i consists of lenticular sandstone blocks surrounded by scaly shale matrix and melange ii is composed of blocks of oceanic material such as basalts cherts and red shale in a scaly matrix of shale melange ii is observed only near the boundaries between melange i and oceanic slabs the fabric of melange i indicates progressive deformation during underthrusting of originally coherent trench fill turbidites layer parallel extension characterizes early deformation and is divided into two stages an early stage formed during normal faulting and a subseguent stage formed perpendicular to the early extension the early extension is interpreted in terms of riedel shear associated with layer parallel shearing and tectonically induced loading normal to the layering the second extension is due to sticking thrust movement late deformation of melange i is represented by folding in association with layer parallel shearing this appears to be related to compression just before or during underplating of melange i beneath the accretionary prism layer parallel shear extends downward due to strain hardening of sheared sediments and then reaches to the base of the sediments subsequently the shear zone penetrates pelagic sediments and finally oceanic basement at this time melange ii is formed by the shearing an imbricated stack of melanges i ii and oceanic slabs forms duplexes during the underplating process the weak metamorphism of the melange complex in the study area suggests that underplating occurs at shallow depths where trench fill is thin

neogene strike slip faulting in sakhalin and the japan sea opening we describe structural data from a 2000 km n s dextral strike slip zone extending from northern sakhalin to the southeast corner of the japan sea satellite images field data and focal mechanisms of earthquakes in sakhalin are included in the interpretation since miocene time the deformation in sakhalin has been taken up by n s dextral strike slip faults with a reverse component and associated en echelon folds narrow en echelon neogene basins were formed along strike sup faults and were later folded in a second stage of deformation we propose a model of basin formation along extension al faults delimitating dominos between two major strike slip faults and subsequent counterclockwise rotation of the dominos in a dextral transpressional regime basins becoming progressively oblique to the direction of maximum horizontal compression and undergoing shortening the association of both dextral and compressional focal mechanisms of earthquakes indicates that the same transpressional regime still prevails today in sakhalin we present fault set measurements undertaken in noto peninsula and yatsuo basin at the southern end of the sakhalin east japan sea strike slip zone early and middle miocene formations recorded the same transtensional regime as observed along the west coast of ne honshu during the early and middle miocene the strike slip regime was transpressional to the north in sakhalin and hokkaido and transtensional to the south along the west coast of ne honshu as far as noto peninsula and yatsuo basin dextral motion accommodated the opening of the japan sea as a pull apart basin with the tsushima fault to the west the opening of the japan sea ceased at the end of the middle miocene when transtension started to change to e w compression in the japan arc subduction of the japan sea lithosphere under the japan arc started 1 8 ma ago the evolution of the stress regime from transtensional to compressional in the southern part of the strike slip zone is related to the inception of the subduction of the young philippine sea plate lithosphere under the japan arc during the late miocene subduction related extension is a necessary condition for the opening of the japan sea two possible mechanisms can account for dextral shear in this area 1 counterclockwise rotation of crustal blocks due to the collision of india with asia 2 extrusion of the okhotsk sea block squeezed between the north america and eurasia plates

synoptic view of the north atlantic oscillation abstract this article investigates the synoptic characteristics of individual north atlantic oscillation nao events by examining the daily evolution of the potential temperature field on the nominal tropopause the 2 pvu surface this quantity is obtained from the national centers for environmental prediction national center for atmospheric research ncep ncar reanalysis dataset for the winter season for both phases the nao is found to originate from synoptic scale waves as these waves evolve into the low frequency nao pattern they break anticyclonically for the positive phase and cyclonically for the negative phase the results of this analysis suggest that it is the remnants of these breaking waves that form the physical entity of the nao throughout the nao events for both phases the nao is maintained by the successive breaking of upstream synoptic scale waves when synoptic scale disturbances are no longer present mixing processes play an important role in the nao decay as in other recent

structural analysis of turtle mountain alberta using digital elevation model toward a progressive failure abstract in 1903 the eastern slope of turtle mountain alberta was affected by a 30 m m 3 rockslide named frank slide that resulted in more than 70 casualties assuming that the main discontinuity sets including bedding control part of the slope morphology the structural features of turtle mountain were investigated using a digital elevation model dem using new landscape analysis techniques we have identified three main joint and fault sets these results are in agreement with those sets identified through field observations landscape analysis techniques using a dem confirm and refine the most recent geology model of the frank slide the rockslide was initiated along bedding and a fault at the base of the slope and propagated up slope by a regressive process following a surface composed of pre existing discontinuities the dem analysis also permits the identification of important geological structures along the 1903 slide scar based on the so called sloping local base level slbl an estimation was made of the present unstable volumes in the main scar delimited by the cracks and around the south area of the scar south peak the slbl is a method permitting a geometric interpretation of the failure surface based on a dem finally we propose a failure mechanism permitting the progressive failure of the rock mass that considers gentle dipping wedges 30 the prisms or wedges defined by two discontinuity sets permit the creation of a failure surface by progressive failure such structures are more commonly observed in recent rockslides this method is efficient and is recommended as a preliminary analysis prior to field investigation

dynamics of the enso teleconnection and nao variability in the north atlantic european late winter abstractthe winter extratropical teleconnection of el nino southern oscillation enso in the north atlantic european nae sector remains controversial concerning both the amplitude of its impact

zonal asymmetries teleconnections and annular patterns in a gcm the influence of zonally asymmetric boundary conditions on the leading modes of variability in a suite of atmospheric general circulation models is investigated the set of experiments consists of nine model configurations with varying degrees and types of zonal asymmetry in their boundary conditions the structure of the leading eof varies with the zonal asymmetry of the base state for each model configuration in particular a close relationship is found between the structure of the eof and the model storm tracks an approximately linear relationship is found to hold between the magnitude of the zonal asymmetry of the leading eof and of the storm tracks in the models it is shown that this linear relationship extends to the observations one point correlation maps centered on the regions where the eofs reach their maximum amplitude show similar structures for all configurations these structures consist of a north south dipole resembling the observed structure of the north atlantic oscillation nao they are significantly more zonally localized than the leading eof but do resemble one point correlation maps and sector eofs calculated for a simulation with zonally symmetric boundary conditions thus the leading eof for each simulation appears to represent the longitudinal distribution of zonally localized nao like patterns this longitudinal distribution appears to be tied to the distribution of high frequency eddies as represented by the storm tracks a detailed momentum budget for each case confirms that high frequency eddies play a crucial role in producing the nao like patterns other dynamical processes also play an important role but vary with the details of the simulation

the frank slide a reexamination of the failure mechanism the frank slide involving an estimated 30 million m3 of rock occurred in 1903 on the east face of turtle mountain southwestern alberta canada it resulted in the loss of approximately 70 lives

tertiary geodynamics of sakhalin nw pacific from anisotropy of magnetic susceptibility fabrics and paleomagnetic data abstract sakhalin has been affected by several phases of cretaceous and tertiary deformation due to the complex interaction of plates in the northwest pacific region a detailed understanding of the strain is important because it will provide constraints on plate scale processes that control the formation and deformation of marginal sedimentary basins anisotropy of magnetic susceptibility ams data were obtained from fine grained mudstones and siltstones from 22 localities in sakhalin in order to provide information concerning tectonic strain ams data reliably record ancient strain tensor orientations before significant deformation of the sediments occurred paleomagnetically determined vertical axis rotations of crustal rocks allow rotation of the fabrics back to their original orientation results from southwest sakhalin indicate a n035 e directed net tectonic transport from the mid paleocene to the early miocene which is consistent with the present day relative motion between the okhotsk sea and eurasian plates reconstruction of early late miocene ams fabrics in east sakhalin indicates a tectonic transport direction of n040 e in west sakhalin the transport direction appears to have remained relatively consistent from the oligocene to the late miocene but it has a different attitude of n080 e this suggests local deflection of the stress and strain fields which was probably associated with opening of the northern tatar strait a northward directed tectonic transport is observed in miocene sediments in southeast sakhalin mid eocene sediments in east sakhalin and in late cretaceous rocks of west and northern sakhalin which may be associated with northwestward motion and subduction of the pacific plate in the tertiary period the boundaries of the separate regions defined by the ams data are consistent with present day plate models and therefore provide meaningful constraints on the tectonic evolution of sakhalin

comments on the growth of accretionary wedges uplift within accretionary foreland wedges has been explained by the development of duplexes which provides a mechanism for underplating in submarine accretionary wedges with little deformation in the upper part of the wedge we interpret duplex development beneath the costa rica forearc a zone widely considered to be a prime example of nonaccretion because of the apparent absence of an imbricate fan of thrusts at the toe of the wedge large scale structural geometry of accretionary wedges is compatible with low angle trenchward dipping backstops in centrist to reverse angle backstops used commonly in models of return flow within wedges which have been invoked to explain the presence of high p t metamorphic rocks we suggest that emplacement of high p t metamorphic rocks are better explained in a collisional setting where known uplift rates are high than by flow within noncollisional accretionary wedges

paleomagnetic data from alaska reliability interpretation and terrane trajectories virtually the entire body of paleomagnetic data collected from southern alaska depicts a clear decrease in paleolatitude with increasing age strongly suggesting that southern alaska represents a displaced terrane in this paper paleomagnetic studies from southern alaska have been classified with respect to a quality index that is based on four criteria these criteria are the presence of both polarities of magnetic remanence stepwise thermal or alternating field demagnetization of specimens principal component analysis of demagnetization data and a successful fold test of the 51 studies compiled only four from southern alaska and one from western canada are demonstrated to satisfy all criteria and fall therefore in the category of group 3 highly reliable two studies from southern alaska satisfy three of the four criteria lacking both polarities of characteristic remanence and are judged to be of group 2 reliable two of these paleomagnetic studies constrain the accretion time of the southern alaska terrane to the relatively stationary region of central alaska north of the denali fault four paleomagnetic studies from the southern alaska terrane show a distinct paleolatitude anomaly when compared with their expected paleolatitudes from the north american apparent polar wander path using the model of engebretson et al 1984 a series of models are presented to best fit these highly reliable and reliable paleomagnetic studies the model preferred in this article assumes an accretion time with north america of 50 ma and documents pre 50 ma displacement of the southern alaska terrane on the kula plate if the ghost rocks paleomagnetic magnetizations plumley et al 1983 are assumed to be of earliest tertiary age this model fits all of the low paleolatitudes observed in southern alaska models incorporating coastwise translation of the southern alaska terrane along the western boundary of the north america plate and a 50 ma suturing age of this terrane to north america do not satisfy the paleomagnetic constraints four of the reliable studies can be modeled assuming strike slip motion of the southern alaska terrane along the western boundary of the north america plate if a 40 ma suturing age is assumed in this model however the paleomagnetic data must be presumed to represent the highest permissible paleolatitude and the ghost rocks formation paleolatitudes are problematically lower than is possible to model with coastwise translation

reconstruction of subduction and back arc spreading in the nw pacific and aleutian basin clues to causes of cretaceous and eocene plate reorganizations the eocene 50 45 ma major absolute plate motion change of the pacific plate forming the hawaii emperor bend is thought to result from inception of pacific plate subduction along one of its modern western trenches subduction is suggested to have started either spontaneously or result from subduction of the izanagi pacific mid ocean ridge or from subduction polarity reversal after collision of the olyutorsky arc that was built on the pacific plate with ne asia here we provide a detailed plate kinematic reconstruction of back arc basins and accreted terranes in the northwest pacific region from japan to the bering sea since the late cretaceous we present a new tectonic reconstruction of the intraoceanic olyutorsky and kronotsky arcs which formed above two adjacent oppositely dipping subduction zones at 85 ma within the north pacific region during another pacific wide plate reorganization we use our reconstruction to explain the formation of the submarine shirshov and bowers ridges and show that if marine magnetic anomalies reported from the aleutian basin represent magnetic polarity reversals its crust most likely formed in an 85 to 60 ma back arc basin behind the olyutorsky arc the olyutorsky arc was then separated from the pacific plate by a spreading ridge so that the 55 to 50 ma subduction polarity reversal that followed upon olyutorsky ne asia collision initiated subduction of a plate that was not the pacific hence this polarity reversal may not be a straightforward driver of the eocene pacific plate motion change whose causes remain enigmatic

zonal eddy dynamics of the north atlantic oscillation abstract this research is an attempt to understand the dynamical mechanisms that drive the wintertime north atlantic oscillation nao on monthly and longer timescales in an earlier work by deweaver and nigam the authors showed that momentum fluxes from stationary waves play a large role in maintaining the zonal mean zonal wind u perturbations associated with the nao in this paper a linear stationary wave model is used to show that zonal mean flow anomalies in turn play a large role in maintaining the nao stationary waves a strong two way coupling thus exists between u and the stationary waves in which each is both a source of and a response to the other when forced by zonal eddy coupling terms terms that represent the interaction between nao covariant zonal mean zonal wind anomalies and the climatological eddy flow together with heating and transient fluxes the model produces a realistic simulation of the observed stationary wave pattern zonal eddy coupling terms make the largest contribution

interannual variability in north atlantic weather data analysis and a quasigeostrophic model abstractthis paper addresses the effect of interannual variability in jet stream orientation on weather systems over the north atlantic basin nab the observational analysis relies on 65 yr of ncep ncar reanalysis 1948 2012 the total daily kinetic energy of the geostrophic wind gtke is taken as a measure of storm activity over the north atlantic the nab is partitioned into four rectangular regions and the winter average of gtke is calculated for each quadrant the spatial gtke average over all four quadrants shows striking year to year variability and is strongly correlated with the north atlantic oscillation nao the gtke strength in the northeast quadrant is closely related to the diffluence angle of the jet stream in the northwest quadrant to gain insight into the relationship between the diffluence angle and its downstream impact a quasigeostrophic baroclinic model is used the results show that an initially zonal jet persists at its initial latitude over 30 days or longer while a tilted

extrusion tectonics of the okhotsk plate northeast asia based on focal mechanism geologic and lineament data faulting in the chersky range northeast asia changes from right lateral transpression between north america and eurasia to left lateral strike slip between north america and the okhotsk plate the location of the okhotsk eurasia boundary is poorly constrained available data suggest this boundary is right lateral the okhotsk plate is being compressed and extruded from between north america and eurasia resulting in high levels of microseismic activity along the southern flanks of the chersky range

structural evolution of the shimanto belt accretionary complex in the area of the gokase river kyushu sw japan the shimanto belt of sw japan is an accretionary complex which developed between late cretaceous and late miocene the deeper levels of this complex are exposed along the gokase river of eastern kyushu deformation in this region took place as a result of southeasterly directed accretionary thrusting resulting in the development of folds fabrics and melanges all these structures may be attributed to progressive top to the se shearing and the melanges show many similarities to other rock types in fault or shear zones it is also possible to apply shear zone models to explain extensional structures developed perpendicular to thrust transport direction it is suggested that deformation took place during underplating beneath the developing prism

storm track dynamics this paper reviews the current state of observational theoretical and modeling knowledge of the midlatitude storm tracks of the northern hemisphere cool season observed storm track structures and variations form the first part of the review the climatological storm track structure is described and the seasonal interannual and interdecadal storm track variations are discussed in particular the observation that the pacific storm track exhibits a marked minimum during midwinter when the background baroclinicity is strongest and a new finding that storm tracks exhibit notable variations in their intensity on decadal timescales are highlighted as challenges that any comprehensive storm track theory or model has to be able to address physical processes important to storm track dynamics make up the second part of the review the roles played by baroclinic processes linear instability downstream development barotropic modulation and diabatic heating are discussed understanding of these processes forms the core of our current theoretical knowledge of storm track dynamics and provides a context within which both observational and modeling results can be interpreted the eddy energy budget is presented to show that all of these processes are important in the maintenance of the storm tracks the final part of the review deals with the ability to model storm tracks the success as well as remaining problems in idealized storm track modeling which is based on a linearized dynamical system are discussed perhaps on a more pragmatic side it is pointed out that while the current generation of atmospheric general circulation models faithfully reproduce the climatological storm track structure and to a certain extent the seasonal and enso related interannual variations of storm tracks in depth comparisons between observed and modeled storm track variations are still lacking

combining digital elevation model analysis and run out modeling to characterize hazard posed by a potentially unstable rock slope at turtle mountain alberta canada abstract turtle mountain in alberta canada has become an important field laboratory for testing different techniques related to the characterization and monitoring of large slope mass movements as the stability of large portions of the eastern face of the mountain is still questionable in order to better quantify the volumes potentially unstable and the most probable failure mechanisms and potential consequences structural analysis and runout modeling were preformed the structural features of the eastern face were investigated using a high resolution digital elevation model hrdem according to displacement datasets and structural observations potential failure mechanisms affecting different portions of the mountain have been assessed the volumes of the different potentially unstable blocks have been calculated using the sloping local base level slbl method based on the volume estimation two and three dimensional dynamic runout analyses have been performed calibration of this analysis is based on the experience from the adjacent frank slide and other similar rock avalanches the results will be used to improve the contingency plans within the hazard area

mesozoic paleomagnetism of the taigonos peninsula the sea of okhotsk implications to kinematics of continental and oceanic plates abstract mesozoic island arc and oceanic volcanic sedimentary complexes were sampled at eight localities at the taigonos peninsula on the northern coast of the sea of okhotsk out of more than 250 samples most proved to be completely remagnetized at the final stage of deformation by the end of early cretaceous this pervasive remagnetization is probably related to onset of volcanic activity in the okhotsk chukotka belt geological data and overall agreement of these remagnetization directions with the eurasian and north american reference values imply that the taigonos peninsula did not move with respect to the continental margin since the early cretaceous a pre remagnetization remanence was isolated only from middle upper jurassic cherts where mean direction of a prefolding component d 296 i 54 a95 4 5 after tilt correction was determined by combining four component directions and 20 remagnetization circles these results imply the original position of the cherts at about 35 n and their later northward transport over more than 3000 km geological data indicate docking of the studied chert units during the second half of the early cretaceous kinematic analysis shows that the only permissible scenario includes chert accumulation and subsequent motion on the izanagi plate and docking to the continental margin at about 115 ma it means that this plate was being subducted under the active margin of siberia during the early cretaceous and thus the convergent boundary of the izanagi and farallon plates in the central north pacific was located much to the east from its earlier proposed position

paleomagnetism of a late cretaceous island arc complex from south sakhalin east asia convergent boundaries far away from the asian continental margin the hokkaido sakhalin fold system stretches for 1500 km along the eastern coast of asia and consists of several n s trending tectonic belts studies in south sakhalin show that the northern part of the tonino aniva peninsula ozersk unit is a counterpart of the tokoro belt on hokkaido japan in the eastern part of the ozersk unit 195 hand samples were sampled at 20 sites from campanian maastrichtian tuffaceous siltstones and sandstones of the chayka formation of island arc affinity stepwise thermal demagnetization isolates a postfolding low to intermediate temperature component b of normal polarity a high temperature component a is isolated from about half the samples because of strong overlap of unblocking temperature spectra of these two components in other samples direct observations and remagnetization circles were combined for calculation of site mean directions component a is mostly of reversed polarity a few samples of normal polarity are found at three sites the presence of two polarities with approximately antipodal directions and the positive fold test imply a prefolding and most probably primary origin of component a a formation mean inclination of 45 0 6 4 calculated with the aid of inclination only statistics corresponds to a latitude of 26 6 5 2 n a similar inclination is derived from a late cretaceous island arc complex from the tokoro belt on hokkaido since both mean inclinations are 30 lower than the coeval eurasian reference value a large scale northward transport of the entire tokoro island arc is inferred we exclude the possibility of displacement with the kula plate and coast parallel transport instead intra oceanic motion with the pacific plate and docking at the eurasian margin at circa 30 ma are inferred combined paleomagnetic data from the tokoro belt the nemuro belt and kamchatka region imply that a system of intra oceanic island arcs existed in the northwest pacific in late cretaceous time

structural constraints on deep seated slope deformation kinematics abstract a significant sackung type deep seated slope gravitational deformation dsgsd was recognised for the first time by the authors in the middle part of valfurva east of bormio rhaetian alps italy the reconstruction of its kinematics age and state of activity is presented through a detailed description of its morphological geomechanical and structural features an integrated multi disciplinary approach was performed to achieve a clear comprehension of the phenomenon field surveys and aero photo interpretation were carried out in order to clarify the structural geological and geomorphological setting in which the dsgsd developed a kinematic conceptual model of the slope deformation was developed through the analysis of morpho structures of their significance and relationships with lithological markers and quaternary deposits after a geomechanical characterisation of the rock mass involved in the slope deformation numerical modelling was performed to verify the hypotheses made on kinematics and driving factors of the phenomenon the sackung affects pre permian metapelites metabasites and marbles belonging to the upper austroalpine basement of the campo nappe as well as late pleistocene and holocene glacial and rock glacier deposits the deformation started after the late wurmian age 15 000 11 000 years b p and continued until few centuries ago not excluding a present day low rate activity deformation consists in a large oblique sagging along a deep confined sliding surface associated with gravitational reactivation of pre existing late alpine and recent tectonic brittle structures leading to the formation of n s and wnw ese trending gravitational morpho structures the evolution of the wnw ese trending system resulting in asymmetric trenches led to progressive failure of the lower part of the slope during the last 10 000 years as testified by large paleo landslide accumulations and it is still in progress numerical modelling indicates post glacial unloading as the main triggering factor of the slope deformation the importance of this deep seated slope deformation is enhanced by the occurrence of the 30 mm 3 active ruinon landslide in the lower part of the slope such landslide is subjected to rapid evolution and threatens the valley floor establishing an important risk factor connected to human lives and socio economic activities

non annular hemispheric signature of the winter north atlantic oscillation sensitivity experiments with an atmospheric general circulation model agcm without a proper stratosphere are performed to locally force a north atlantic oscillation nao like response in order to analyse the tropospheric dynamics involved in its hemispheric extent results show that the circulation anomalies are not confined to the north atlantic basin not even within the first 10 days of integration where the atmospheric response propagates downstream into the westerly jets at this linear stage transient eddy activity dominates the emerging regional nao like pattern while zonal eddy coupling may add on top of the wave energy propagation later at the quasi equilibrium nonlinear stage the atmospheric response emphasizes a wavenumber 5 structure embedded in the westerly jets associated with transient eddy feedback upon the atlantic and pacific storm tracks this agcm waveguided structure rightly projects on the observational nao related circumglobal pattern providing evidence of its non annular character in the troposphere these findings support the view on the importance of the circumglobal waveguide pattern on the development of nao related anomalies at hemispheric level it could help to settle a consensus view of the arctic oscillation which has been elusive so far

statistical significance of the fold test in palaeomagnetism summary the significance of the change in direction dispersion on applying the fold test in palaeomagnetism is used as the criterion for deciding whether or not the fold test has statistical significance a set of tables is compiled which can be used for quick application of the test

on the reduced north atlantic storminess during the last glacial period the role of topography in shaping synoptic eddies the north atlantic storminess of last glacial maximum lgm fully coupled climate simulations is generally less intense than that of their pre industrial pi counterparts despite having stronger baroclinicity an explanation for this counterintuitive result is presented by comparing two simulations of the ipsl full climate model forced by pmip3 paleoclimate modelling intercomparison project phase 3 lgm and pi conditions two additional numerical experiments using a simplified dry general circulation model forced by idealized topography and a relaxation in temperature provide guidance for the dynamical interpretation the forced experiment with idealized rockies and idealized laurentide ice sheet has a less intense north atlantic storm track activity than the forced experiment with idealized rockies only despite similar baroclinicity both the climate and idealized runs satisfy or support the following statements the reduced storm track intensity can be explained by a reduced baroclinic conversion which itself comes from a loss in eddy efficiency to tap the available potential energy as shown by energetic budgets the eddy heat fluxes are northeastward oriented in the western atlantic in lgm and are less well aligned with the mean temperature gradient than in pi the southern slope of the laurentide ice sheet topography forces the eddy geopotential isolines to be zonally oriented at low levels in its proximity this distorts the tubes of constant eddy geopotential in such a way that they tilt northwestward with height during baroclinic growth in lgm while they are more optimally westward tilted in pi

cenozoic intracontinental dextral motion in the okhotsk japan sea region a right lateral shear zone trending northerly along more than 2000 km is recognized from central japan to northern sakhalin it was active mainly during the neogene and has accommodated several hundreds of kilometers of displacement the whole structure of sakhalin is built on this shear zone en echelon sigmoidal folds and thrusts en echelon narrow miocene basins and a major discontinuity which is observed along more than 600 km the tym poronaisk fault characterize the deformation there in hokkaido en echelon folds and thrusts and a ductile shear zone with high temperature metamorphism constitute the southern extension of this transpressional shear zone it continues to the south as a zone of transtensional deformation along the eastern margin of japan sea as en echelon basins and dextral transfer faults observed as far south as noto peninsula and yatsuo basin the style of the shear zone thus evolves from transpressional in the north far from the subduction zone to transtensional in the south in the back arc region strike slip motion along this shear zone was primarily responsible for the dextral pull apart opening of japan sea during the early and middle miocene dextral motion is still active in the north along the tym poronaisk fault in sakhalin as well as on the continental margin of japan sea korea and asia mainland active e w compression replaced the dextral motion along the eastern margin of japan sea in late miocene time and incipient subduction began in the early quaternary

rotational atmospheric circulation during north atlantic european winter the influence of enso the dominant variability modes of the north atlantic european rotational flow are examined by applying a principal component analysis pca eof to the 200 hpa streamfunction mid winter anomalies jan feb monthly means the results reveal that when this norm is used the leading mode eof1 does not correspond to the traditional north atlantic oscillation nao which appears in our analysis as the second leading mode eof2 but is the local manifestation of the leading hemispheric streamfunction eof the regression of this regional mode onto the global sst field exhibits a clear el nino signature with no signal over the atlantic while the associated upper height anomalies resemble the tropical northern hemisphere tnh pattern east of north america this tnh like wavetrain produces a meridional dipole like pattern at lower levels although in some ways this pattern resembles the nao eof2 the dynamics of these two modes are very different in that only eof2 is associated with a latitudinal shift of the north atlantic stormtrack thus the choice of the streamfunction norm in the eof analysis allows the separation of two different phenomena that can produce similar dipolar surface pressure anomalies over the north atlantic but that have different impact on european climate these two modes also differ on their contribution to variability at lower levels while nao eof2 is mostly confined to the north atlantic tnh eof1 has a more annular global character at upper levels nao eof2 also produces a global pattern but with no annular structure reminiscent of the circumglobal teleconnection

anatomy of synoptic eddy nao interaction through eddy structure decomposition abstracta method of eddy structure decomposition is proposed to detect how low frequency flow associated with the north atlantic oscillation nao organizes systematically synoptic eddy se activity to generate in phase and upstream feedbacks in this method a statistical eddy streamfunction ses field defined by the three point covariance of synoptic scale streamfunction is introduced to characterize spatiotemporal se flow structures the ses field is decomposed into basic and anomalous parts to represent the climatological se flow structure and its departure these two parts are used to calculate the basic and anomalous eddy velocity eddy vorticity and thus eddy vorticity flux fields in order to elucidate those two se feedbacks onto the nao this method is validated by the fact that the observed anomalous eddy vorticity flux field can be reproduced well by two linear terms the basic eddy velocity field multiplied by anomalous eddy vorticity field and the anomalous eddy velocity field multiplied

lateral spreading processes in mountain ranges insights from an analogue modelling experiment abstract the results of a study on gravitational induced lateral spreading phenomena are here reported the lateral spreading processes are widely represented in the italian apennines due to the widespread overlapping of stiff rock masses on more ductile ones the stress strain evolution of these processes was investigated by combining an analogical and a numerical modelling approach the analogue modelling reproduced the evolution of a carbonate ridge thrust over a clayey flysch with reference to the case study of mt roccatagliata mt sant angelo ridge the rock mass juxtaposition was reproduced in a laboratory experiment by overlapping a brittle concrete on a viscous ductile material these materials were selected with rheological properties physically scaled with respect to the natural rock mass prototypes the spreading phenomenon was modelled by opening horizontal panels in sequential stages and monitoring the resulting stresses within the ductile material during the experiment a stress strain modelling was also performed by an fdm numerical solution this modelling replied the laboratory experiment by testing the use of different rheological constitutive laws the resulting stresses and morphological evolutions are comparable with the analogical laboratory experiment only if a time dependent rheological behaviour is assumed for the ductile material the results show that lateral spreading processes can be properly investigated by combining analogue and numerical modelling techniques which take into account the viscous plastic behaviour of the used materials

involvement of old crustal materials during formation of the sakhalin island russian far east and its paleogeographic implication constraints from detrital zircon ages of modern river sand and miocene sandstone abstract in order to decipher crustal nature of the sakhalin island in russian far east we carried out detrital zircon u pb age analyses on miocene sandstone and river sand from the longest river poronay river of the sakhalin island the detrital zircon data from two river sand samples display similar age distribution patterns with a dominant mesozoic age group subordinate age peaks at 1 8 ga and 2 5 ga and a few paleozoic and neoproterozoic grains the miocene sandstone shows age peaks at 22 84 260 and 497 ma respectively and a few paleo proterozoic grains these age groups indicate that abundant old crustal materials have been involved in the crustal formation of the sakhalin island detrital zircon result reveals two episodes of post accretion magmatism from the sakhalin island in ages of 37 ma and 22 21 ma they can be correlated with coeval post accretion magmatic events in the hokkaido island supporting the geological correlation between the sakhalin island and the hokkaido island comparison of detrital zircon dating result from the sakhalin island with those from surrounding blocks and cratons in eastern asia allows us to propose two possible sources in eastern asia the bureya jiamusi khanka block with the sikhote alin orogenic belt to its west and the south china craton the detrital zircon result indicates that the formation of the sakhalin island should be close to the east asia continent rather than as an independent intro oceanic island arc within the pacific ocean similar to formation of the japanese islands the south china craton may have played an important role during formation of the sakhalin island

continental margin tectonics submarine accretionary prisms submarine accretionary prisms are sites of incipient mountain building where sediments and rocks of the deep ocean are uplifted deformed and ultimately transformed to continental crust accretionary prisms develop at sites of lithospheric convergence that is subduction zones commonly accretionary prisms form along continental margins although accretionary prisms may also occur adjacent to island arcs which are ultimately coalesced into continental landmasses here we review the studies of submarine accretionary prisms during the past four years with primary focus on the contributions of geoscientists from the united states

large sackung along major tectonic features in the central italian alps deep seated gravitational slope deformation sackung is common in alpine mountain belts it is controlled by lithological geomorphological and structural features we describe and discuss five examples of dsgsd along the insubric line periadriatic fault in the central italian alps the five examples are different in morphology size state of activity and distribution and are located along both primary and secondary valleys we demonstrate relations between structural and gravitational features and discuss the possibility that structural has both passive and active roles in sackung development analysis of ps sar data shows that the studied examples are not active today numerical modelling demonstrates the importance of lithological and structural constraints postglacial debuttressing groundwater fluctuations and weathering on sackung triggering and development

structural characterization of turtle mountain anticline alberta canada and impact on rock slope failure abstract this paper proposes a structural investigation of the turtle mountain anticline alberta canada to better understand the role of the different tectonic features on the development of both local and large scale rock slope instabilities occurring in turtle mountain the study area is investigated by combining remote methods with detailed field surveys in particular the benefit of terrestrial laser scanning for ductile and brittle tectonic structure interpretations is illustrated the proposed tectonic interpretation allows the characterization of the fracturing pattern the fold geometry and the role of these tectonic features in rock slope instability development ten discontinuity sets are identified in the study area their local variations permitting the differentiation of the study zone into 20 homogenous structural domains the anticline is described as an eastern verging fold that displays considerable geometry differences along its axis and developed by both flexural slip and tangential longitudinal strain folding mechanisms moreover the origins of the discontinuity sets are determined according to the tectonic phases affecting the region pre folding folding post folding the localization and interpretation of kinematics of the different instabilities revealed the importance of considering the discrete brittle planes of weakness which largely control the kinematic release of the local instabilities and also the rock mass damage induced by large tectonic structures fold hinge thrust

zonal asymmetry of the annular mode and its downstream subtropical jet an idealized model study abstractthis study investigates linkages between the zonal asymmetry of the annular mode am zonal pattern and the subtropical jet stj over its downstream regions of the storm track by using an idealized model observational analyses show that the am zonal patterns are more zonally asymmetric during days when the stj downstream of the storm track is unusually strong and vice versa in the idealized model the stj downstream of the storm track is varied by introducing an additional zonally localized tropical heating the model s am variability exhibits a nearly zonally uniform structure when there is no or only weak tropical heating however the signatures of the am are locally strengthened in the heating sector thus the am zonal pattern is zonally asymmetric when the tropical heating is large enough to create a strong stj the model results also show that the percentage of the variance explained by the am the persistence of the am index and the intensity of eddy feedback are also increased when t

estimation of rock mass deformation modulus and strength of jointed hard rock masses using the gsi system abstract rock mass characterization is required for many applications in rock engineering practice including excavation design support design stope design amongst others for these purposes it is necessary to obtain design input parameters such as deformation moduli and strength parameters for numerical modeling although such parameters can ultimately be determined from in situ tests at the preliminary design stage where access to underground is limited the practical way to obtain these parameters is to apply a rock mass classification system to characterize the rock mass and estimate the rock mass properties over the years many classification systems such as rqd rock mass rating q and geological strength index gsi systems have been developed amongst them the q system is widely used for rock support system design and the gsi system is used for estimating design parameters the gsi system is the only rock mass classification system that is directly linked to engineering parameters such as mohr coulomb hoek brown strength parameters or rock mass modulus however the application of the existing gsi system is hindered by the facts that the use of the system is to some extent subjective and requires long term experience in the present study a quantitative approach to assist in the use of the gsi system is presented it employs the block volume and a joint condition factor as quantitative characterization factors the approach is built on the linkage between descriptive geological terms and measurable field parameters such as joint spacing and joint roughness the newly developed approach adds quantitative means to facilitate use of the system especially by inexperienced engineers the gsi system is applied to characterize the jointed rock masses at two underground powerhouse cavern sites in japan gsi values are obtained from block volume and joint condition factor which in turn are determined from site construction documents and field mapping data based on gsi values and intact rock strength properties equivalent mohr coulomb strength parameters and elastic modulus of the jointed rock mass are calculated and compared to in situ test results the point estimate method is implemented to approximate the mean and variance of the mechanical properties of the jointed rock masses it is seen that both the means and variances of strength and deformation parameters predicted from the gsi system are in good agreement with field test data

frost weathering and rockwall erosion in the southeastern swiss alps long term 1994 2006 observations abstract rates and processes of frost weathering in the alps were investigated by visual observations of intensively shattered rocks continuous monitoring of frost wedging and rock temperatures in bedrock and measurements of rockfall activity rapid frost weathering of hard intact rocks occurs along lakes and streams where seasonal freezing promotes ice segregation in the rock otherwise rocks require pre existing weakness or a long exposure period for intensively shattered automated monitoring shows that crack opening occurs at three scales including small opening accompanying short term frost cycles slightly larger movements during seasonal freezing and occasional large opening originating from refreezing of snow melt water during seasonal thawing the opening events require at least partial water saturation in the crack the repetition of crack opening frost wedging results in permanent opening and finally debris dislocation debris collections below fractured rockwalls show that pebble falls occur at an average rate of about 0 1 mm a 1 with significant spatial and inter annual variations occasional large boulder falls significantly raise the rockwall erosion rates controlled by such factors as the joint distribution in the bedrock repetition of annual freeze thaw cycles and extraordinary summer thaw

kinematic model for the opening of the sea of japan and the bending of the japanese islands we have analyzed paleomagnetic data from japan reported over the past 25 years in combination with marine geophysical and on land geologic data to reconstruct the opening of the sea of japan and the bending of honshu from these data we propose that the sea of japan opened by a two stage back arc spreading event 1 in the early to middle tertiary japan began to rift off the asian coast as a single rigid block rotated clockwise approximately 25 and formed the japan basin 2 in the miocene the yamato and tsushima basins opened and shortly thereafter 19 ma the japan arc collided with another island arc in central hokkaido at this stage honshu began to behave as two rigid blocks southwest honshu and northeast honshu southwest honshu continued to rotate clockwise approximately 45 as the yamato and tsushima basins continued to open northeastern honshu rotated counterclockwise approximately 40 as hokkaido was held fixed by the arc collision while the yamato basin continued to open these two events the opening of the tsushima and yamato basins and the arc collision in hokkaido resulted in the early to middle miocene bending of the japan arc observed in the paleomagnetic data after 12 ma back arc spreading ceased

paleomagnetism and geochronology of the late cretaceous paleogene island arc complex of the kronotsky peninsula kamchatka russia kinematic implications the remnants of ancient island arcs are exposed in the achayvayam valagina and east peninsulas tectonic zones of the olutor kamchatka region northeast russia geochemically late cretaceous to paleogene island arc complexes of the east peninsulas zone are similar to intraoceanic island arcs and the east peninsulas zone is regarded as the extinct kronotsky island arc paleomagnetic and biostratigraphic studies of late cretaceous and paleogene island arc rocks were carried out at 21 sites in the eastern part of the kronotsky peninsula which belongs to the east peninsulas zone characteristic remanent magnetizations of both polarities isolated from most sites pass reversal and fold tests the cretaceous result is also supported by a positive conglomerate test on lava boulders from an intraformational conglomerate mean inclinations of late cretaceous ypresian and bartonian rocks correspond to paleolatitudes of 44 8 8 0 n 38 6 3 5 n and 45 1 7 0 n respectively these values are 20 lower than the corresponding reference values for the north american plate for the cretaceous and ypresian and 14 lower for the bartonian therefore northward transport of the kronotsky island arc is indicated kinematic evolution of the kronotsky island arc in the late cretaceous paleogene was reconstructed using published kinematic parameters in addition we incorporated into analysis the geological and published paleomagnetic data for the late cretaceous and tertiary island arc complexes of the cape kamchatka peninsula from the east peninsulas zone and the late cretaceous island arc complexes of the achayvayam valagina zone as a result two alternative scenarios of kinematic evolution for the kronotsky island arc are proposed according to both of them the kronotsky island arc was moving with the continental plate in late cretaceous time and with the pacific plate from the beginning of the paleocene until docking with the eurasian margin in miocene pliocene time

paleomagnetic evidence for block rotations in central hokkaido south sakhalin northeast asia abstract the eocene to lower miocene strata in the bykov region of south sakhalin island far east russia show a mean paleomagnetic direction of dec 28 7 inc 55 7 95 6 7 and n 22 and a paleomagnetic pole at 66 3 n 245 7 e and a95 8 8 which shows that south sakhalin rotated 25 15 clockwise with respect to northeast asia since the early miocene this pole agrees with that of the eocene to middle miocene sedimentary rocks in central hokkaido japan it suggests that both south sakhalin and central hokkaido have rotated clockwise with respect to northeast asia since the early miocene these clockwise rotations can be interpreted as a vertical axis rotation of the blocks distributed in the north south direction more than 1000 km along the dextral hokkaido sakhalin shear zone considering the development of an en echelon structure of the basins in the shear zone we recognized five blocks each of which had rotated since the early miocene we conclude that this dextral shear is responsible not only for these block rotations but also for the opening of the kuril basin and the japan sea and that the shear motion was caused by oblique convergence between the eurasian and the okhotsk plates since the early miocene

initiation of subduction zones along transform and accreting plate boundaries triple junction evolution and forearc spreading centres implications for ophiolitic geology and obduction

before the frank slide the frank slide occurred on the east limb of the turtle mountain anticline which was thrust up along the folded and splayed turtle mountain fault easterly dipping paleozoic limestones and dolomi

geometric test for late cretaceous paleogene intracontinental transform faulting in the canadian cordillera the tintina trench northern rocky mountain trench tt nrmt fault zone and the fraser river straight creek fr sc fault zone are separate en echelon concentric small circle fault segments of a composite intracontinental transform fault zone more than 2500 km long that cuts diagonally across the canadian cordillera from the outboard part of a tectonic collage of accreted foreign terranes in the south into the north american preaccretionary continental margin in the north most of the 450 km of right hand slip on the tt nrmt fault zone was transformed southward during the late cretaceous and paleocene into oblique convergence in the southern canadian rockies the remainder probably comprising less than 100 km was transformed southwestward during early and middle eocene time via a zone of distributed shear and east west crustal stretching into right hand slip on the en echelon fr sc fault zone these interpretations based on regional systematic mapping of geologic structures are in conflict with interpretations of paleomagnetic measurements that call for more than 1000 km of post mid cretaceous right hand displacement along the general locus of the tt nrmt fault zone involving foreign terranes and the parts of north america to which they had been accreted this paradox must be resolved

the shapes of cold high mountains in sedimentary rocks abstract terzaghi geotechnique 12 1962 251 and young young a 1972 slopes oliver and boyd edinburgh 288 pp described the stable forms of slopes in sedimentary rock masses assuming penetrative discontinuities which are parallel to bedding and joints which are perpendicular to bedding the only movements considered were slides along bedding experience in the canadian rockies indicates that the cohesionless rock masses that exist at or above tree line may also move by toppling buckling and sliding along joints these processes also act to limit the inclinations of stable slopes rock strength is a factor in the critical height of a slope that buckles the processes can be represented as fields on a process diagram a plot of slope inclination against bedding dip using the basic friction angles of the rocks present the process diagram also separates five common mountain peak shapes which form on homoclinal sequences of beds castellate and matterhorn mountains occur in sub horizontal beds cuestas develop in gently to moderately dipping beds hogbacks formed in moderately to steeply dipping beds have similar slope angles on both cataclinal and anaclinal slopes dogtooth mountains occur in steeply dipping sub vertical beds

on the dynamics of a storm track abstract an idealized primitive equation model is used to determine the factors controlling the dynamics and maintenance of eddy activity in a storm track the results show that localized regions of enhanced baroclinicity do not necessarily lead to localization of eddy activity by studying the energetics of the storm track it is shown that while baroclinic conversion does indeed correlate with the region of maximum baroclinicity it is the downstream radiation of energy through the ageostrophic geopotential fluxes which acts as a trigger for the development and maintenance of eddy activity over less baroclinic regions extending the region of eddy activity much further downstream from the region of high baroclinicity examples of eddy life cycles are given that show that convergence and divergence of ageostrophic fluxes can dominate baroclinic and barotropic conversion especially in regions with weak baroclinicity factors that may limit the zonal extent of a storm track are discussed evidence of down

eddy zonal flow interactions and the persistence of the zonal index abstract an idealized atmospheric general circulation model is used to investigate the factors controlling the time scale of intraseasonal 10 100 day variability of the extratropical atmosphere persistence on these time scales is found in patterns of variability that characterize meridional vacillations of the extratropical jet depending on the degree of asymmetry in the model forcing patterns take on similar properties to the zonal index annular modes and north atlantic oscillation it is found that the time scale of jet meandering is distinct from the obvious internal model time scales suggesting that interaction between synoptic eddies and the large scale flow establish a separate intraseasonal time scale a mechanism is presented by which eddy heat and momentum transport couple to retard motion of the jet slowing its meridional variation and thereby extending the persistence of zonal index and annular mode anomalies the feedback is strong and quite sensitive to model parameters when the mod

from deep seated slope deformation to rock avalanche destabilization and transportation models of the sierre landslide switzerland abstract sackung is a widespread post glacial morphological feature affecting alpine mountains and creating characteristic geomorphological expression that can be detected from topography over long time evolution internal deformation can lead to the formation of rapidly moving phenomena such as a rock slide or rock avalanche in this study a detailed description of the sierre rock avalanche sw switzerland is presented this convex shaped postglacial instability is one of the larger rock avalanche in the alps involving more than 1 5 billion m3 with a run out distance of about 14 km and extremely low fahrboschung angle this study presents comprehensive analyses of the structural and geological characteristics leading to the development of the sierre rock avalanche in particular by combining field observations digital elevation model analyses and numerical modelling the strong influence of both ductile and brittle tectonic structures on the failure mechanism and on the failure surface geometry is highlighted the detection of pre failure deformation indicates that the development of the rock avalanche corresponds to the last evolutionary stage of a pre existing deep seated gravitational slope instability these analyses accompanied by the dating and the characterization of rock avalanche deposits allow the proposal of a destabilization model that clarifies the different phases leading to the development of the sierre rock avalanche

the tectonics of the okhotsk sea abstract the northern and central parts of the okhotsk sea form an epimesozoic platform the hetero aged acoustic basement is represented by deformed geosynclinal rocks from cretaceous to precambrian in age the slightly deformed sedimentary cover levelled the uneven surface of the acoustic basement and this upper paleogene neogene cover filled up the system of the structural basins the general nw se and w e extensions of the taphrogenic horsts and grabens of the acoustic basement were formed due to extension and subsidence of the earth s crust during the late paleogene neogene

wave maintained annular modes of climate variability abstract the leading modes of month to month variability in the northern and southern hemispheres are examined by comparing a 100 yr run of the geophysical fluid dynamics laboratory gcm with the ncep ncar reanalyses of observations the model simulation is a control experiment in which the ssts are fixed to the climatological annual cycle without any interannual variability the leading modes contain a strong zonally symmetric or annular component that describes an expansion and contraction of the polar vortex as the midlatitude jet shifts equatorward and poleward this fluctuation is strongest during the winter months the structure and amplitude of the simulated modes are very similar to those derived from observations indicating that these modes arise from the internal dynamics of the atmosphere dynamical diagnosis of both observations and model simulation indicates that variations in the zonally symmetric flow associated with the annular modes are forced by eddy fluxes in the free troposphere while

arctic oscillation or north atlantic oscillation abstract the definition and interpretation of the arctic oscillation ao are examined and compared with those of the north atlantic oscillation nao it is shown that the nao reflects the correlations between the surface pressure variability at its centers of action whereas this is not the case for the ao the nao pattern can be identified in a physically consistent way in principal component analysis applied to various fields in the euro atlantic region a similar identification is found in the pacific region for the pacific north american pna pattern but no such identification is found here for the ao the ao does reflect the tendency for the zonal winds at 35 and 55 n to anticorrelate in both the atlantic and pacific regions associated with the nao and pna because climatological features in the two ocean basins are at different latitudes the zonally symmetric nature of the ao does not mean that it represents a simple modulation of the circumpolar flow an increase in the ao or nao implies stro

multidecadal and interannual changes of stationary rossby waves changes in stationary rossby waves srw are connected to regional climate change and the propagation of these waves has a large influence on the evolution and development of the general circulation since the late 1970s and early 1980s many studies have noted a major shift in the structure of large scale circulation occurring in both hemispheres this paper explores the changes in the srw pattern and their propagation associated with these climate shifts first multidecadal changes in srw activity are examined using ncep ncar reanalysis data for two periods 1948 1978 and 1979 2000 for comparison of these two periods the zonal wind srw kinetic energy pattern along the waveguide and stationary wavenumber ks are analysed the results showed that in the northern hemisphere nh the srw propagation is favoured in the asian jet stream ajs waveguide ks 7 in the period 1979 2000 mainly in the east asia region there are indications that this could be associated with the pacific decadal oscillation warm phase a favoured srw propagation also occurs in the north atlantic subtropical jet nasj waveguide ks 5 region in the latter period and could be linked with positive north atlantic oscillation in the southern hemisphere sh a favoured srw propagation in the polar jet waveguide ks 4 region is observed in the latter period and this could be associated indirectly with tropical sea surface temperature fluctuations the interannual changes in the srw propagation during stronger el nino and la nina events which occurred from 1948 to 2000 are then examined the results showed that during stronger el nino events in nh the srw propagation in the ajs mainly in the east asia region and in the nasj waveguides ks 7 5 respectively is reduced on the other hand in sh the srw propagation in australian and polar waveguides ks 7 4 respectively is favoured copyright 2011 royal meteorological society

an introductory review on gravitational deformation induced structures fabrics and modeling abstract recent studies have pointed out a similarity between tectonics and slope tectonic induced structures numerous studies have demonstrated that structures and fabrics previously interpreted as of purely geodynamical origin are instead the result of large slope deformation and this led in the past to erroneous interpretations nevertheless their limit seems not clearly defined but it is somehow transitional some studies point out continuity between failures developing at surface with upper crust movements in this contribution the main studies which examine the link between rock structures and slope movements are reviewed the aspects regarding model and scale of observation are discussed together with the role of pre existing weaknesses in the rock mass as slope failures can develop through progressive failure structures and their changes in time and space can be recognized furthermore recognition of the origin of these structures can help in avoiding misinterpretations of regional geology this also suggests the importance of integrating different slope movement classifications based on distribution and pattern of deformation and the application of structural geology techniques a structural geology approach in the landslide community is a tool that can greatly support the hazard quantification and related risks because most of the physical parameters which are used for landslide modeling are derived from geotechnical tests or the emerging geophysical approaches

on the existence of storm tracks abstract given that middle latitude weather systems transport heat in a manner such as to weaken the baroclinicity that is thought to be crucial to their growth it is perhaps surprising that concentrated regions of such eddy activity i e storm tracks are found in the northern hemisphere winter the existence and possible self maintenance of storm tracks is investigated using a linear stationary wave model with storm track region forcings taken from data averaged over a number of winters it is found that the direct thermal effect of the eddies does indeed act against the existence of the storm track their vorticity fluxes lead to some reduction of this effect it is argued that the mean diabatic heating in the storm track region is an indirect eddy effect this heating is found to maintain the mean maximum in baroclinicity in the region further the mean low level flow induced by the eddy effects is such as to enhance the warm western oceanic boundary currents that are crucial to the existence of t

how multiple foliations may control large gravitational phenomena a case study from the cismon valley eastern alps italy abstract the right slope of the high cismon valley trento province italy carved into the poly deformed phyllites of the south alpine basement shows evidence of differential quaternary slope evolution which highly depends on how the slope intersects the inherited structures in the study area the regional schistosity outlines a kilometer scale nnw sse trending fold with close flanks and an axial plane dipping to the ne the structure obliquely intersects the nne ssw trending slope so that the northern part of the slope follows the upper limb of the fold and the southern sector coincides with the lower limb and the hinge the secondary axial plane foliation is typically incipient at the fold flanks and much more pervasive and fan shaped near the hinge zone this foliation as well as the asymmetric polyharmonic secondary folds has significant consequences on rock mass mechanical properties and on mechanisms and timing of the gravitational phenomena developed along the slope in particular the joint compressive strength jcs and the geological strength index gsi obtained on stable outcrops outside the deforming area display a decrease from north to south this points to a progressive deterioration of the rock mass strength which directly reflects the influence of the pre existing fabric the results obtained by the analysis of lidar derived digital elevation model show evidence of two different gravitational movements located in the northern and southern sectors of the slope respectively the northern side is characterized by an ongoing deep seated gravitational slope deformation dsgsd likely triggered by post glacial unloading derived from the retreat of the ice tongue that filled the cismon valley during the last glacial maximum lgm conversely the southern part of the slope is the expression of a fully evolved pre lgm gravitational collapse this heterogeneous behavior of the slope is most likely controlled by the secondary foliation and asymmetric polyharmonic folds the former being of paramount importance for the release of the mobilized mass at the crown area and the latter easing or impeding the downslope movement although it is widely accepted that the regional foliation is the dominant controlling factor of dsgsds on poly deformed and highly foliated metamorphic basement our work suggests that the secondary foliation as well as parasitic folds may also have remarkable effects on slope evolution if favorably oriented and sufficiently pervasive

a mechanism and simple dynamical model of the north atlantic oscillation and annular modes a simple dynamical model is presented for the basic spatial and temporal structure of the large scale modes of intraseasonal variability and associated variations in the zonal index such variability in the extratropical atmosphere is known to be represented by fairly well defined patterns and among the most prominent are the north atlantic oscillation nao and a more zonally symmetric pattern known as an annular mode which is most pronounced in the southern hemisphere these patterns may be produced by the momentum fluxes associated with large scale midlatitude stirring such as that provided by baroclinic eddies it is shown how such stirring as represented by a simple stochastic forcing in a barotropic model leads to a variability in the zonal flow via a variability in the eddy momentum flux convergence and to patterns similar to those observed typically the leading modes of variability may be characterized as a mixture of wobbles in the zonal jet position and pulses in the zonal jet strength if the stochastic forcing is statistically zonally uniform then the resulting patterns of variability as represented by empirical orthogonal functions are almost zonally uniform and the pressure pattern is dipolar in the meridional direction resembling an annular mode if the forcing is enhanced in a zonally localized region thus mimicking the effects of a storm track over the ocean then the resulting variability pattern is zonally localized resembling the north atlantic oscillation this suggests that the north atlantic oscillation and annular modes are produced by the same mechanism and are manifestations of the same phenomenon the time scale of variability of the patterns is longer than the decorrelation time scale of the stochastic forcing because of the temporal integration of the forcing by the equations of motion limited by the effects of nonlinear dynamics and friction for reasonable parameters these produce a decorrelation time of the order of 5 10 days the model also produces some long term 100 days or longer variability without imposing such variability via the external parameters except insofar as it is contained in the nearly white stochastic forcing

organization of storm tracks in zonally varying flows abstract a simple two layer quasigeostrophic model is employed to investigate the sensitivity of storm tracks to changes in an externally imposed zonally varying large scale flow zonally asymmetric temperature and horizontal deformation fields are varied systematically in order to compare the effects of baroclinicity and horizontal deformation on storm track dynamics the sensitivity of the storm tracks to uniform barotropic zonal flows is also examined the results show two competing processes for storm track organization one associated with a local maximum in baroclinicity and the other with a local minimum in horizontal deformation when the equilibrium state consists of a zonally symmetric temperature field and a barotropic stationary wave the maximum in synoptic scale transient eddy energy storm track is located in the entrance region of the upper jet just downstream of the point of minimum horizontal deformation as zonal variations in baroclinicity become large keeping the upper layer horizo