convectively forced internal gravity waves results from two dimensional numerical experiments two dimensional numerical simulations were performed to investigate the nature of tropospheric internal gravity waves of the type which are observed to occur above active thermal convection over an unstable boundary layer these gravity waves are believed to be excited by a combination of pure thermal forcing and by the boundary layer eddies and cumulus clouds acting as obstacles to the flow in the presence of mean environmental wind shear large amplitude internal gravity waves were obtained in the simulations with amplitudes and horizontal scales similar to the 12 june 1984 aircraft observations over western nebraska this was a day with strong wind shear in the lowest 3 km above the ground and with scattered cumulus clouds topping the boundary layer the simulations show that there is significant difference between the early time solutions as might be predicted by linear theory and late time solutions for the boundary layer eddy structure a layer interaction occurs in which gravity waves of the stable layer are excited by the boundary layer convection there is evidence to suggest that this layer interaction occurs both with and without shear but that it is stronger in the presence of low level shear results indicate that shear or the obstacle effect is a more efficient generator of gravity waves than is the pure thermal forcing the simulations show that the gravity waves initially forced by the boundary layer eddies lead to a feedback mechanism that acts to organize the boundary layer eddies and the cumulus convection the solutions suggest that the character of fair weather convection moist or dry is a non local problem involving at times the full depth of the troposphere the clouds produced in the simulations have very little influence on the wave field or boundary layer eddy structure as they are relatively small cumuli on the other hand the clouds are strongly influenced by the interactions between the wave and eddy fields upshear growth of cumulus clouds similar to that which is frequently observed in nature is reproduced in the simulations the development of feeder feeder is used here in a dynamical sense only clouds on typically the upshear side of the cloud is found to be a result of the interaction between the gravity wave field and the dry and moist convection the relative phase velocity between the gravity waves and the cloud plays a crucial role in determining the character of the cumulus cloud growth in the present simulations these simulations suggest that the dynamics both internal and external to the boundary of a cumulus cloud is a complicated mix between wave dynamics and the usually considered convection dynamics a brief discussion of the implications of the present results to cloud boundary baroclinic instability dynamics is also presented

an analysis of the intraplate earthquake 2016m5 8_gy that occurred in the gyeongsang basin in the se of the korean peninsula based on 3 d modelling of the gravity and magnetic field

dendrochronology and lichenometry colonization growth rates and dating of geomorphological events on the east side of the north patagonian icefield chile this paper highlights the importance for dating accuracy of initial studies of delay before colonization for both trees and lichens and tree age below core height particularly in recently deglaciated terrain where colonization and growth rates may vary widely due to differences in micro environment it demonstrates for the first time how dendrochronology and lichenometry can be used together in an assessment of each other s colonization and growth rates and then cross correlated to provide a supportive dating framework the method described for estimating tree age below core height is also new the results show that on the east side of the north patagonian icefield in the arco and colonia valleys nothofagus age below a core height of 112 cm can vary from 5 to 41 years and delay before colonization may range from a maximum of 22 years near water to a minimum of 93 years on the exposed flanks of the arenales and colonia glaciers tree age plus colonization delay supplied a maximum growth rate of 4 7 mm year for the lichen placopsis perrugosa and lichen colonization is estimated to take from 2 5 to approximately 13 years a minimum lichenometric date of 1883 was estimated for an ice formed trimline at the junction of the arenales and colonia glaciers and a maximum dendrochronological date of 1881 for a water formed trimline in the arco valley tree and lichen ages around the valley suggest that a glacial outburst drained the 1881 high level lake releasing approximately 265 million cubic metres of water repeated flooding with a minimum of 38 high lake levels is suggested by horizontal sediment lines on the arco valley walls and moraine flanks dating confirmed diminishing flood levels with a last minor flood in 1963 the wider significance of the work is that it should produce more accurate dating of recent glacier fluctuations around the north patagonia icefield an area where dated reference surfaces are extremely scarce

regional strike slip in the eastern continental margin of korea and its tectonic implications for the evolution of ulleung basin east sea sea of japan air gun profiles delineate a large scale strike slip fault system along the eastern continental margin of korea this system comprises two right stepping curvilinear master faults hupo and yangsan faults that are closely associated with en echelon nominal faults and reverse faults and folds these structural features indicate two phases of regional deformation in the earlier phase late oligocene to early miocene the margin experienced extensional shear strain with dextral strike slip movements along the hupo and yangsan faults that guided a pull apart opening of the pohangyoungduk basin the later phase deformation late miocene to early pliocene was governed by shortening strain that induced a convergent strike slip reactivation of the hupo fault as well as widespread contractile faulting and folding the regional deformation in the eastern korean continental margin reflects three stages of tectonic evolution of the ulleung basin 1 pull apart opening stage from late oligocene to early miocene 2 rotational opening stage with a differential rotation of the japanese arc in middle miocene and 3 back arc closing stage from the end of middle miocene to present

japan sea a pull apart basin abstract recent field work in the hokkaido central belt and marine geology studies along the eastern margin of japan sea in addition to previously published data lead us to propose a new model of opening of the japan sea the synthesis of both on land and offshore structural data gives new constraints about the structural evolution of the system the rhombohedral shape of the japan basin and the particular tectonic behaviour of the margins on both east and west sides can be explained by an early eo oligocene rifting of a pull apart basin accommodated along two large right lateral shear zones east of korea and west of northeast japan and sakhalin it is followed during upper oligocene lower miocene by the main opening of the japan basin as a mega pull apart then a back arc spreading probably related to the subduction process induced the creation of the yamato and tsushima basins at the end of lower miocene and in middle miocene clockwise rotation of southwest japan larger than 20 or major bending of honshu mainland deduced from paleomagnetic studies is unlikely at this time since 1 or 2 my b p to present compression prevails along the eastern margin of the japan sea the generation of marginal basins as pull apart basins along intracontinental strike slip faults is a mechanism which has been proposed by other authors concerning the south china sea the question then is whether the fragmentation of the asiatic continent is an intracontinental deformation related process as proposed here or a subduction related one

sea level records at 80 ka from tectonically stable platforms florida and bermuda studies from tectonically active coasts on new guinea and barbados have suggested that sea level at 80 ka was significantly lower than present whereas data from the atlantic and pacific coasts of north america indicate an 80 ka sea level close to that of the present we determined ages of corals from a shallow submerged reef off the florida keys and an emergent marine deposit on bermuda both localities are on tectonically stable platforms distant from plate boundaries uranium series ages show that corals at both localities grew during the 80 ka sea level highstand and geologic data show that sea level at that time was no lower than 7 9 m below present florida and may have been 1 2 m above present bermuda the ice volume discrepancy of the 80 ka sea level estimates is greater than the volume of the greenland or west antarctic ice sheets comparison of our ages with high latitude insolation values indicates that the sea level stand near the present at 80 ka could have been orbitally forced

paleomagnetism of tertiary rocks from the oga peninsula and the rotation of northeast japan we have made a paleomagnetic study of tertiary rocks from the oga peninsula northern honshu island volcanic and sedimentary rocks were sampled from 26 sites in the peninsula the ages of the rocks range from 62 ma to the present the results indicate a counterclockwise rotation of northeast japan with respect to eastern asia around a pole at 58 n 149 e between about 22 ma and 15 ma the amount of the rotation is about 20 before the rotation northeast japan was situated along the east coast of the asian continent

lichenometric dating using rhizocarpon subgenus rhizocarpon in the patagonian andes argentina abstract this study represents the first attempt to develop and apply lichenometric dating curves of rhizocarpon subgenus rhizocarpon for dating glacier fluctuations in the patagonian andes six glaciers were studied along the patagonian andes surfaces of known ages historical evidences and tree ring analyses were used as control sites to develop indirect lichenometric dating curves dating curves developed for the studied glaciers show the same general logarithmic form indicating that growth rate of subgenus rhizocarpon decreases over time the strong west east precipitation gradient across the andean cordillera introduces statistically significant differences in the growth curves with faster growth rates in the moist west sites than the drier eastern sites latitudinal difference among the studied glaciers does not appear to be a major factor regulating lichen growth rates therefore we developed two lichenometric curves for dating glacier fluctuations in wetter and drier sites in the patagonian andes during the past 450 yrs application of the developed curves to moraine dating allowed us to complement glacial chronologies previously obtained by tree ring analyses a first chronosequence for moraine formation in the torrecillas glacier 42 s is presented our findings confirm the utility of lichenometry to date deglaciated surfaces in the patagonian andes

stream analysis of small drainage basins in an ancient landform korean peninsula abstract much of the topography of korea is ancient but many quaternary fault outcrops and marine terraces have been observed in the southeastern part of the korean peninsula sufficient evidence of a quaternary fault is lacking in the geological features of the commercially developed jukbyun and uljin areas knickpoints that develop on streams can be formed by tectonic activity such as faulting and folding or can result simply from the differential erosion rates of bedrock in this study we investigated the relationship between stream steepness and faults in the jukbyun area stream profile analyses of the bugu and namdae basins were performed using a digital elevation model to estimate quaternary tectonic movements stream parameters obtained from analysis of the longitudinal stream profiles of the bugu and namdae drainage basins in the northeastern part of the korean peninsula indicated neotectonic movement thirty of the thirty nine knickpoints that developed in the downstream areas of the fluvial channels corresponded to fault zones it is thought that fault activity results in knickpoints in river systems the normalized relative slope k sn value 54 9 of the bs1 stream in the bugu drainage basin was higher than that 28 8 36 3 of the other streams in both basins despite a similar lithology to ns1 and ns2 therefore we concluded that stream steepness might be a result of tectonic forcing rather than a product of rock strength in the study area and that stream parameters could provide indirect evidence of quaternary tectonics in ancient landforms

mechanisms for the mesoscale organization of tropical cloud clusters in gate phase iii part i shallow cloud bands abstract mesoscale cloud clusters are a frequently observed feature of the tropical atmosphere and are primarily responsible for the observed large scale vertical mass flux given that the forcing for such convection comes from widely separated horizontal scales boundary layer motions on the scale of 1 km and weak ascent on a scale of over 1000 km the persistent organization of cloud clusters into the scale 10 50 km presents an important problem in this article part i two and three dimensional numerical simulations of convection under a capping inversion at 2 km are presented to demonstrate that the mechanism responsible for mesoscale organization of clouds requires neither deep convection nor large scale forcing the case study used as a basis for these simulations is one of several instances reported by lemone and meitin of mesoscale cloud bands during gate phase iii these observations are remarkable in that the cloud bands are shallow yet possess a rather large horizontal periodicity in the ra

predicted bounds on peak global mean sea level during marine isotope stages 5a and 5c abstract estimates of marine isotope stage mis 5c and 5a global mean sea level gmsl based on marine terraces and coastal indicators range from 15 37 m and 9 30 m below present respectively tectonic displacement and glacial isostatic adjustment gia complicate efforts to refine this range we revisit this issue using numerical predictions of post glacial sea level change and updated estimates of site specific tectonic signals based upon these predictions laurentide and cordilleran peripheral bulge dynamics and variations in the gravitational effect of these ice masses dominate the gia signal along the east and west coasts of north america published compilations suggest that mis 5 sea level indicators extending from virginia to the caribbean lie on the outer flank of the peripheral bulge while those along a transect from oregon to baja california sit on the inner flank of the bulge our gia modeling reconciles these data by adopting a significantly weaker i e lower viscosity upper mantle in analyzing data on the pacific coast relative to the atlantic an inference supported by seismic tomography we present a sensitivity analysis that compares the observed elevation of globally distributed high stand markers to a suite of gia simulations that vary the earth model and gmsl from the last interglaciation mis 5e 130 115 ka to 70 ka we conclude that gmsl peaked at 8 5 4 6 m 1 during mis 5a and 9 4 5 3 m during mis 5c a more restrictive analysis yields slightly wider bounds corresponding to 10 5 5 5 m and 11 1 6 6 m respectively

bent structural trends of japan flexural slip folding related to the neogene opening of the sea of japan the trend of the pre miocene structures of japan is bent in kyushu and central japan on land geologic features such as the trend of synmetamorphic jurassic lineations neocomian basins and late cretaceous strike slip faults have distorted trends as a result of the miocene opening of the sea of japan accentuation of the bending in central japan could be due to the pliocene quaternary collision of japan with the izu ridge a preopening reconstruction of japan is proposed the bent structural trends of kyushu and central japan along with neogene fault motions are explained by a two dimensional model of broad scale flexural slip folding

the blake geomagnetic polarity episode recorded in chinese loess a geomagnetic anomaly consisting of three clearly defined periods of reverse polarity separated by two short intervals of normal polarity has been documented in a loess section near xining western china on the basis of previous studies of chinese loess stratigraphy we correlate this geomagnetic polarity episode with the blake event while more research is needed to improve our understanding of the exact process of remanence acquisition of loess deposits this study shows that loess may provide records of fast geomagnetic events and lends further support to the global nature of the blake geomagnetic event

horizontal convective rolls determining the environmental conditions supporting their existence and characteristics abstract data from the convection and precipitation electrification cape project as well as results from numerical simulations are used to study horizontal convective rolls the environmental conditions necessary for sustaining rolls and for influencing the aspect ratio ratio of roll wavelength to convective boundary layer cbl depth and orientation are examined observations and numerical model simulations both suggest that a moderate surface sensible heat flux and some vertical wind shear are necessary for roll existence unlike some previous studies however it is shown that rolls occurred within very low cbl shear conditions 2 10 3 s 1 in addition the low level i e 200 m shear seems to be more important than the shear through the depth of the cbl in roll sustenance the aspect ratio is shown to be proportional to the cbl instability measured in terms of the monin obukhov length the roll orientation is similar to the wind direction at 10 m agl the cbl wind direction the inversio

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

mechanism of backarc opening in the japan sea role of asthenospheric injection abstract the process of backarc extension in the japan sea includes two modes of spreading the parallel and rotational or fan shape opening data from paleomagnetism for rocks on the northeast japan arc radiometric age determination for dredged volcanic rocks and heat flow in the basin have suggested that the parallel opening of the japan sea took place earlier than the rotational opening at 21 14 ma the mechanism of opening of the japan sea has been examined based on the secular change in the geometry of the subducted slab and in the volcanic activity on the northeast japan arc mechanisms of backarc rifting including mantle diapirism mantle flow induced by the slab subduction or interaction of the over and the underriding plates cannot reasonably explain the process of opening of the japan sea the most plausible mechanism operating in the spreading process of the japan sea is injection of the asthenosphere into the mantle wedge that forcefully pushed the subducted slab to cause both steepening of the slab and the backarc extension the asthenospheric current towards the northeast japan arc trench system may have been associated with the large scale upwelling of the asthenosphere beneath the northeastern china region that caused intra plate volcanism and produced continental rift systems in the region the present mechanism can also explain the active backarc rifting in the okinawa trough in the western pacific and the taupo depression in north island new zealand

vertical deformation of lacustrine shorelines along breached relay ramps catlow valley fault southeastern oregon usa abstract vertical deformation of pluvial lacustrine shorelines is attributed to slip along the catlow valley fault a segmented basin and range style normal fault in southeastern oregon usa the inner edges of shorelines are mapped along three breached relay ramps along the fault to examine the effect of fault linkage on the distribution of slip shoreline inner edges act as paleohorizontal datums so deviations in elevation from horizontal outside of a 2 m error window are taken to be indications of fault slip the sites chosen represent a spectrum of linkage scenarios in that the throw on the linking fault compared to that on the main fault adjacent to the linking fault varies from site to site results show that the maturity of the linkage between segments i e larger throw on the linking fault with respect to the main fault does not control the spatial distribution of shoreline deformation patterns of shoreline deformation indicate that the outboard linking and or smaller ramp faults have slipped since the shorelines formed observations indicate that displacement has not fully localized on the linking faults following complete linkage between segments

elevations and ages of marine terraces and late quaternary rock uplift in southeastern korea 1 from a detailed gps survey of marine terraces and their former shoreline elevations along the southeastern coast of the korean peninsula we determined the pattern of late quaternary uplift in a part of the far eastern intraplate region of the eurasian plate using a paleosea level of 6 m for the 117 132 ka sea level highstand the average long term uplift rates are 0 3 m ka in the weolsung and 0 2 m ka in the daebo gori regions persistent uplift that generated marine terraces is mostly the result of local major faulting reflecting an ene wnw maximum compression stress the differences in uplift rates suggest a local triangular crustal block undergoing structural movement controlled by subregional tectonic processes notable local major faulting in an intraplate region plays an important role in raising the emergent flight of marine terraces generated by earthquakes

geomorphic disequilibrium in the eastern korean peninsula possible evidence for reactivation of a rift flank margin abstract tectonically inactive since the middle miocene the korean peninsula is generally considered a typical passive continental margin with asymmetric relief with only low levels of seismic activity recent reports of uplift rates as high as 150 350 mm ka 1 from geomorphic markers using numerical dating methods e g radiocarbon optically stimulated luminescence osl and cosmogenic nuclides however cast doubt on the tectonic quiescence of korea thus we evaluate the geomorphic status of eastern korea using denudation rates at geomorphic timescales of 103 106 years which are equivalent to the rates previously reported at local points to infer regional denudation rates we measured catchment wide denudation rates cwdr in 13 watersheds using in situ cosmogenic 10be and 14c analyses of riverine sediment samples in eastern korea these cwdr data suggest that the mean denudation rate during the past 5 14 ka centers around 74 7 25 4 mm ka 1 which is consistent with the long term geologic exhumation rate we derive of 74 10 1 mm ka 1 since the middle miocene however our cwdr data are 2 3 times lower than rates of coastal uplift and river incision of 150 350 mm ka 1 derived from data on marine and fluvial terraces respectively in addition to isotopic analyses we quantified topographic indices such as elevation relief and slope and then compared these indices with cwdrs to examine morphological changes that might be related to tectonic disturbances since the beginning of late pleistocene the relationship between cwdrs and topographic indices indicates that most of the study area rests in a near steady state condition however in contrast to the smooth concave longitudinal profile expected for a steady state landscape topographic analyses reveal the presence of major knickzones confirmed by field reconnaissance these knickzones may have been produced by changes in base level caused by tectonic events lithologic variations or sea level changes our 1 d modeling of knickpoint propagation suggests that tectonic disturbance is the factor most likely to produce knickzones in the study area raising the possibility that erosional signals caused by late pleistocene tectonic disturbance affected channel gradients but that the knickpoints have not yet propagated through the entire catchment area our results suggest that the eastern part of the korean peninsula is approaching but has not completely reached a geomorphic steady state and that transient conditions have been induced by reactivation of the rift flank margin no later than the late pleistocene causing tilting of the central korean peninsula to the west at a rate of 7 0 10 10 m m per year over the past 125 ka

age height and deformation of holocene marine terraces at mahia peninsula hikurangi subduction margin new zealand mahia peninsula is a prominent coastal landmark in eastern north island and is the closest point of land in the north island to the hikurangi trough where the pacific plate plunges beneath the subduction complex at the eastern margin of the australian plate uplifted holocene marine deposits of both estuarine and open beach affinities are found in many parts of the peninsula and provide the basis for holocene tectonic characterization estuarine deposits record the later part of the postglacial transgression that culminated about 6500 years b p in new zealand the deposits have been differentially uplifted since that time at a rate of 2 5 0 3 mm yr in the central north coast area decreasing to 0 7 0 2 mm yr about 6 km to the west the coastal plain is characterised in many places by a stepped sequence of emergent shore platforms overlain by fossiliferous beach deposits extensive radiocarbon dating of samples from beach deposits shows that terraces in widespread parts of the peninsula are of five distinct ages each of the terraces is inferred to have formed in conjunction with a large prehistoric earthquake because of the stepped terrace morphology clustering of ages on each terrace differential uplift of terraces across the peninsula and historic coseismic uplift events in this tectonic setting paleoseismic events of mw 7 5 8 0 are estimated to have occurred approximately 250 1600 1900 3500 and 4500 years b p uplift distribution of the holocene and late pleistocene marine terraces shows that the peninsula lies on the west gentle flank of the active lachlan anticline which is cored by a major west dipping reverse fault the lachlan fault holocene active deformation at mahia peninsula and other coastal areas of eastern north island is a continuation of structures developed in pleistocene time in the landward part of the subduction complex adjacent to the hikurangi subduction zone

counterclockwise rotation of northeast japan paleomagnetic evidence for regional extent and timing of rotation early to late miocene welded tuffs have been sampled from northeast honshu island and the oshima peninsula of hokkaido island japan for paleomagnetic study characteristic directions with a high unblocking temperature component above 560 c are isolated from 24 sites westerly declinations d 1 91 are identified in welded tuffs older than 17 ma from these areas when combined with previous paleomagnetic data from welded tuffs the early miocene paleomagnetic poles derived from northeast honshu island and the oshima peninsula are statistically identical and indicate that northeast honshu island and the oshima peninsula were subjected to counterclockwise rotation as a single tectonic block these results establish that the rotating block of northeast japan extends north to the oshima peninsula to the latitude 43 n the dimension of this rotating block is of the order of 500 km the paleomagnetic data provide a best curve for the rotation process with the counterclockwise rotation reaching a climax at 15 0 ma and a net amount of rotation of 46 4 the 500 km long northeast japan block was rotated counterclockwise through more than 45 and accompanied a clockwise rotation of the 600 km long southwest japan block at about 15 ma

incipient subduction and deduction along the eastern margin of the japan sea the eastern margin of the japan sea has been under convergent tectonics since sometime after the pliocene the suture line is on the ocean continent boundary between the japan yamato basins and the tohoku northeast japan arc incipient subduction and obduction of the oceanic and sub oceanic crust are observed along the suture line with the occurrence of numerous n s trending fault bounded ridges and troughs focal mechanism solutions of several compressional type earthquakes with magnitudes of m 6 9 to 7 7 which have occurred along the zone are consistent with the observation of geological thrust faults the convergent stresses in the japan sea may be due to india eurasia collision and its associated intra plate or inter microplate movements in east asia the eastward movement of the amurian plate causes baikal extension along its western margin and the japan sea convergence along its eastern margin

westward migration of the izu bonin trench northward motion of the philippine sea plate and their relationships to the cenozoic tectonics of japanese island arcs abstract the essential elements in the understanding of the cenozoic island arc tectonics of the japanese islands came from reconstructing the paleo position of the plate boundaries and estimating the change in the philippine sea plate motion by using the 2nd law of the convergence rate of plates it was estimated that the izu bonin trench wandered around 400 km east from its present position during the paleogene and migrated westward thereafter island arc tectonism is related to the convergence rate of plates 1st law of the convergence rate of plates hence the changes in the philippine sea plate motion was examined by compiling paleomagnetic data as a result the main events of the cenozoic tectonics of japan were well explained by the change in the position of the plate boundaries and the change in motion of the philippine sea plate

scale selection in locally forced convective fields and the initiation of deep cumulus abstract deep cumulus dynamics has often been treated as an initial value problem where the long time effect of surface energy fluxes are neglected initiation is often assumed to follow from a strong localized deformation of the flow field which is elsewhere quiescent in nature however the atmosphere is rarely found in an undisturbed condition just prior to the inception of deep growth one likely cause of widespread motions is the natural modal response of the environment to surface energy fluxes which results in a field of disturbances evidence is presented in this paper for the possible existence of a class of solutions when deep convection is allowed to evolve in the context of a thermally forced field of shallow convection this class of solutions is neglected when one visualizes the growth of severe local storms in term of buoyant bubbles in an otherwise tranquil atmosphere considering deep cumulus initiation as a field problem severely limits the concept of an isolated cloud individual clou

differential uplift along the northern margin of the central anatolian plateau inferences from marine terraces abstract emerged marine terraces and paleoshorelines along plate margins are prominent geomorphic markers that can be used to quantify the rates and patterns of crustal deformation the northern margin of the central anatolian plateau has been interpreted as an actively deforming orogenic wedge between the north anatolian fault and the black sea here we use uplifted marine terraces across principal faults on the sinop peninsula at the central northern side of the pontide orogenic wedge to unravel patterns of quaternary faulting and orogenic wedge behavior we leveled the present day elevations of paleoshorelines and dated marine terrace deposits using optically stimulated luminescence osl to determine coastal uplift the elevations of the paleoshorelines vary between 4 0 2 and 67 1 4 m above sea level and osl ages suggest terrace formation episodes during interglacial periods at ca 125 190 400 and 570 ka corresponding to marine isotopic stages mis 5e 7a 11 and 15 mean apparent vertical displacement rates without eustatic correction deduced from these terraces range between 0 02 and 0 18 mm a with intermittent faster rates of up to 0 26 mm a we obtained higher rates at the eastern and southern parts of the peninsula toward the hinterland indicating non uniform uplift across the different morphotectonic segments of the peninsula our data are consistent with active on and offshore faulting across the sinop peninsula when integrated with regional tectonic observations the faulting pattern reflects shortening distributed over a broad region of the northern margin of the central anatolian plateau during the quaternary

japan sea opening history and mechanism a synthesis the respective tectonic effects of back arc spreading and continental collision in asia are considered either as two independent processes or as closely interrelated extrusion tectonics assumes that the opening of the south china sea and the left lateral motion along the red river fault are geometrically linked in a pull apart manner this model is not accepted by several workers because the structural link between the two processes is not clearly demonstrated in the case of the japan sea we can show without ambiguity that back arc opening was controlled by large intracontinental strike slip faults which can be easily understood as effects of the india asia collision far from the indenter the japan sea opened in the early miocene in a broad pull apart zone between two major dextral strike slip shear zones the first one extends from north sakhalin to central japan along 2000 km it has accommodated about 400 km of finite displacement deformation along it varies from dextral transpression in the north to dextral transtension in the south the second is between korea and sw japan and has accommodated a smaller displacement of about 200 km the extensional domain in between lies in the back arc region of japan distributed stretching of the arc crust resulted in the formation of most of the japan sea while localized oceanic spreading at the southern termination of the eastern transpressional shear zone shaped the japan basin the first oceanic crust was formed in a small triangle based on the eastern shear zone and spreading propagated westward inside the pull apart region timing of oceanic crust formation of formation of the dextral shear zones and of block rotation in between as well as the internal structure of the basins and the geometry of deformation along the master shear zones are used to reconstruct the opening history this evolution is discussed by comparison to other manifestations of the arc and back arc activity such as the history of sedimentation and volcanism the paper then suggests that the collision of india can have tectonic consequences as far north as japan and sakhalin and describes the geometrical relation of back arc opening there and diffuse extrusion

estimation of possible maximum earthquake magnitudes of quaternary faults in the southern korean peninsula the korean peninsula is located in the intraplate regime of the eurasian plate and numerous historical and instrumental earthquakes have been recorded among these the largest earthquakes were recorded in and around the gyeongju and ulsan areas in the southeastern part of the korean peninsula we recently reexamined faults in jinhyun and jintee part of the ulsan fault swarm to clarify the average slip rate and the maximum potential magnitude of future earthquakes the jinhyun fault extends to the tabgol fault j t fault and the jintee fault extends to the singye s j fault the faults cut through alluvial fans and are covered by unconsolidated granite washes on tertiary granite all of these faults show reverse sense of motion such that the tertiary granite has been moved upward with a high angle relative to the quaternary sediments most sediment samples from the jinhyun and jintee faults showed quartz osl ages of ca 40 60 ka the calculated vertical slip rate for the jinhyun and jintee faults is in the range of 0 18 0 28 mm y based on maximum earthquake magnitudes calculated from geological survey results as well as historical and instrumental earthquake information the maximum potential magnitudes of future earthquakes in the gyeongju area are estimated to range from 4 6 to 5 6 this suggests that the potential maximum magnitude in the southern korean peninsula is presumably not more than 6

focal mechanisms of recent earthquakes in the southern korean peninsula summary we evaluate the stress field in and around the southern korean peninsula with focal mechanism solutions using the data collected from 71 earthquakes ml 1 9 5 2 between 1999 and 2004 for this the hypocentres were relocated and well constrained fault plane solutions were obtained from the data set of 1270 clear p wave polarities and 46 sh p amplitude ratios the focal mechanism solutions indicate that the prevailing faulting types in south korea are strike slip dominant oblique slip faultings with minor reverse slip component the maximum principal stresses 1 estimated from fault slip inversion analysis of the focal mechanism solutions show a similar orientation with e w trend 269 275 and low angle plunge 10 25 for all tectonic provinces in south korea consistent with the e w trending maximum horizontal stress hmax of the amurian microplate reported from in situ stress measurements and earthquake focal mechanisms the directions of the intermediate 2 and minimum 3 principal stresses of the gyeongsang basin are however about 90 deg off from those of the other tectonic provinces on a common 2 3 plane suggesting a permutation of 2 and 3 our results incorporated with those from the kinematic studies of the quaternary faults imply that nnw to ne striking faults dextral strike slip or oblique slip with a reverse slip component are highly likely to generate earthquakes in south korea

relationship between tectonics volcanism sedimentation and basin development late cenozoic central part of northern honshu japan abstract a pronounced interplay between tectonics volcanism and sedimentation can be established in the volcanic arc region of the central part of northern honshu during the early miocene to quaternary interval four stages are recognized with the type of volcanism and sedimentation varying according to the tectonic stress regime 1 1 rifting stage 22 15 ma ns trending half grabens were formed under an extensional stress regime related to the rifting of the sea of japan basins were rapidly filled by intermediate to felsic volcanic products which are often associated with subaerial fluvial and lacustrine sediments 2 2 back arc basin opening stage 15 13 ma with more advanced stagess of rifting subsidence from crustal stretching resulted in marked marine incursion and an overall transgressive succession developed during this stage the back arc side of northern honshu subsided rapidly to middle bathyal environments at the same time associated with the opening of the sea of japan large volumes of regionally extensive mafic lavas and associated hyaloclastites were erupted within submarine grabens in contrast in the present backbone ranges felsic volcanism occurred within bathyal to shallow marine environments igneous rock types in this stage display a bimodal mafic felsic chemistry 3 3 transitional stage 13 2 4 ma a thermal subsidence substage 13 8 ma an intermediate stress regime developed which included phases of both weak extension and compression consequently grabens along the sea of japan ceased to form later lithospheric cooling eventually led to thermal subsidence of the back arc region and hemipelagic sediments mantled the previously active mafic volcanic apron volcanism at this time was mainly restricted to a narrow zone along the present backbone ranges where felsic to intermediate volcanic products accumulated within shallow marine environments b incipient compressional substage 8 2 4 ma hemipelagic sedimentation continued on the back arc side of northern honshu along the present backbone ranges the intermediate stress regime continued with formation of many large caldera structures associated with subaerial felsic volcanism 4 4 shortening deformation stage 2 4 ma present the change of the absolute direction of motion of the pacific plate at the early to middle pliocene changed the regional stress regime of the volcanic arc from intermediate to compression movement of back arc thrusts along the sea of japan coast began 2 3 ma and led to uplift of the volcanic arc continued compression in the volcanic arc produced narrow uplifted zones with associated basins bounded by reverse faults these basins were filled rapidly by terrestrial sediments containing upward coarsening sequences under this highly compressional tectonic stress regime volcanism became intermediate mafic in composition with large stratovolcanoes becoming prominent

evidence for and implications of a bering plate based on geodetic measurements from the aleutians and western alaska 1 global positioning system gps measurements are used to examine the hypothesis of a clockwise rotating bering plate originally proposed on the basis of seismicity the bering plate encompasses the bering sea western alaska and the aleutian islands gps measurements from the bering plate s interior show south to southwest motions of 3 5 mm a where a is years we construct elastic dislocation models to determine the spatial distribution and intensity of locked patches on the aleutian subduction interface we use these to remove interseismic strain from the gps observation and determine an arc translation velocity for each region of the aleutians revealing south and southwest motions of 4 8 mm a we combine the arc translation rates with measurements from the bering plate s interior sites and estimate the euler pole for the bering plate relative to north america to be located at 42 5 n 121 3 e with an angular speed of 6 0 ma the clockwise rotation of the bering plate may cause left lateral faulting in interior alaska the bering plate s interaction with south central alaska may be responsible for the decreased slip rate on the western denali fault and for contraction across the central alaska range we analyze slip partitioning along the aleutian arc on the basis of both gps measurements and slip azimuths of thrust earthquakes and find a systematic discrepancy between plate convergence direction and slip azimuths we conclude that slip partitioning in the back arc only develops west of amchitka pass whereas slip partitioning in the fore arc is present throughout the arc

a rhizocarpon geographicum growth curve for the cascade range of washington and northern oregon usa lichen thallus measurements from 22 surfaces of known age on mount baker mount hood and mount rainier are used to construct a regional rhizocarpon geographicum growth curve for the cascade range of washington and northern oregon growth rates determined by measuring the largest thallus diameters on the same surfaces at mount rainier in 1976 and 2002 are used for comparison with lichenometric data from mount baker and mount hood similar lichen thallus diameter vs age relationships identified in the data from the three mountains suggest the presence of uniform growth rates over the 400 km range a regional growth curve developed during our study shows three growth phases of successively slower growth a rapid phase from 8 to 20 yr a linear phase from 20 to 145 yr and a slow phase of unknown duration beyond ca 145 yr uncertainty in lichen growth rates beyond 145 yr limits projection of the curve beyond that age however the age range of the constrained growth curve covers an important period of recent climate variability when applied in appropriate settings our growth curve can be used to determine numeric ages to 10 yr for surfaces between 20 and 145 years old in areas where other techniques are not applicable or do not provide unique or well constrained ages

analysis of pinnate joints in the mount desert island granite implications for postintrusion kinematics in the coastal volcanic belt maine the mount desert island granite is cut by fractures displaying one of four types of surface morphology 1 smooth to undulatory 2 stepped in the form of en echelon cracks 3 striated with linear fibers and 4 irregular with cataclastic grains these surfaces belong to joints host fractures with pinnate joints reactivated joints or fractures and deformation bands shear fractures respectively pinnate joints like striations on slickensides are structures indicative of the orientation of a the slip vector and sense of shear on host fractures although fractures in the mount desert island granite cluster into two major sets n20 degree w and n45 degree e host fractures with pinnate joints and shear fractures favor the n45 degree e orientation a kinematic analysis of the pinnate joints indicates a predominantly dextral strike slip sense of movement on northeast trending fractures this result agrees with previous work suggesting that a prominent postintrusion tectonic event in southeast maine consisted of dextral strike slip motion on northeast trending faults

historical seismicity of korea the korean peninsula lies in the eurasian plate neighboring seismically active china and the japanese islands instrumental observation of earthquakes began in korea in 1905 and about one thousand events of mostly small magnitude less than 4 0 have been detected to date in and near the peninsula strain release due to these earthquakes is almost negligible compared to that due to about 2186 historical earthquakes that occurred from 2 to 1904 a d in the peninsula in this study these historical earthquakes are cataloged from korean historical documents and their epicenters and intensities are estimated as best as possible temporal variations of the historical seismicity of korea clearly reveal a very irregular strain release pattern over the nineteen centuries with low to moderate seismicity most of the time except for the unusually high seismicity from the fifteenth to the eighteenth centuries this highly irregular strain release pattern clearly indicates the characteristics of intraplate seismicity of the peninsula epicenters of large earthquakes appear to be well associated with the major faults and the boundaries of major geological units in the peninsula it is to be noted that the major faults associated with large historical earthquakes were created by the mesozoic tectonic activities that severely disrupted crustal layers of the peninsula historical earthquakes occurred all over the peninsula however the northeastern part appears relatively less seismic probably due to the area being less disrupted during the mesozoic the b value in the magnitude frequency relation determined from historical korean earthquakes is 0 71 which is between those of the japanese islands and eastern china and is lower than in many stable intraplate regions online material catalog of historical seismicity of korea 2 1904 a d

unsteady migration of taebaek mountain drainage divide cenozoic extensional basin margin korean peninsula abstract the taebaek mountain range tbr initially formed via extension of a back arc basin in the east sea during the early miocene ca 22 ma and exemplifies a typical escarpment on a passive continental margin the tbr acts as a major watershed and divide across which topography changes from gentle western side slopes to steep eastern slopes compared to the geologic history of the flanking extensional basin which is well known from analysis of its sedimentary fill the post extensional geomorphic history of the escarpment and basin margin has been minimally studied because of a lack of terrestrial archives we determined the rate and cause of divide migration of the tbr using a suite of relatively new geomorphic and geochronologic tools we used geomorphic analyses of relief slope river long profiles swath profiles and parameters to study this transient topography catchment wide denudation rates cwdr using 10be facilitated comparisons of denudation rates of cross divide paired basins denudation rates east of the divide from drainages with steep slopes average nearly two times counterparts with gentle slopes west of the divide gilbert metrics used to assess divide mobility strongly suggest that catchments in the eastern tbr may have captured counterpart catchments in the west both cwdr and gilbert metric results reveal that retreat of the main tbr divide likely accelerated in the late quaternary following tectonic inversion surface uplift and tilting or flexure in the eastern tbr geomorphic disequilibrium across the current divide of the tbr continues until the present

kinematic interpretation of remnant en echelon rift segments of the southwestern japan sea abstract the southwestern japan sea and the margin of southwestern japan feature parallel elongate extensional sub basins and grabens these structures are oblique to the trend of southwestern japan and are interpreted as the remnant of an en echelon array such a right stepping remnant en echelon pattern indicates sinistral rifting of the southwestern japan block from asia the major extensional fault trends are parallel over a distance of 600 km infinitesimal kinematic relations show that it is unlikely that these faults initiated in response to rotation about the nearby pole determined from paleomagnetic studies rather an earlier stage of rifting about a distant pole is indicated the rotational pole of this early rifting was probably located at least 6000 km away from the rift and the pole of rotation was offset from the rift trend by a similar distance rifting about this distant rotational pole loosened the southwestern japan continental block from the asian mainland making it susceptible to a large rotation about a nearby pole

u th dating of marine isotope stage 7 in bahamas slope sediments in order to understand the driving forces for pleistocene climate change more fully we need to compare the timing of climate events with their possible forcing in contrast to the last interglacial marine isotope stage mis 5 the timing of the penultimate interglacial mis 7 is poorly constrained this study constrains its timing and structure by precise u th dating of high resolution n 18 o records from aragonite rich bahamian slope sediments of odp leg 166 sites 1008 and 1009 the major glacial interglacial cycles in n 18 o are distinct within these cores and some mis 7 substages can be identified these sediments are well suited for u th dating because they have uranium concentrations of up to 12 ppm and very low initial 230 th contributions with most samples showing 230 th 232 th activity ratio of s 75 u and th concentrations and isotope ratios were measured by thermal ionisation mass spectrometry and multiple collector inductively coupled plasma mass spectrometry with the latter providing dramatically better precision twenty nine of the 41 samples measured have a n 234 u value close to modern seawater suggesting that they have experienced little diagenesis ages from 27 of the 41 samples were deemed reliable on the basis of both their u and their th isotope ratios ages generally increase with depth although we see a repeated section of stratigraphy in one core extrapolation of constant sedimentation rate through each substage suggests that the peak of mis 7e lasted from v237 to 228 ka and that 7c began at 215 ka this timing is consistent with existing low precision radiometric dates from speleothem deposits the beginning of both these substages appears to be slightly later than in orbitally tuned timescales the end of mis 7 is complex but also appears to be somewhat later than is suggested by orbitally tuned timescales although this event is not particularly well defined in these cores fl 2002 elsevier science b v all rights reserved

the mendocino triple junction active faults episodic coastal emergence and rapid uplift a complex zone of rapid holocene surface uplift and deformation occurs at the mendocino triple junction the juncture of three plate bounding faults the cascadia subduction zone san andreas fault and mendocino fault within this mountainous structural knot up to 1 4 m of coastal emergence occurred during the 1992 cape mendocino m s 7 1 earthquake surveying and radiometric dating of ancient marine strandlines 7 5 along the cascadia subduction zone megathrust however another plausible interpretation of the data is that multiple earthquakes resulting in smaller amounts of net surface uplift per event similar to the 1992 earthquake occurred closely spaced in time giving the appearance in the geologic record of less frequent and larger events regardless of the number and timing of paleoearthquakes the number of platforms is a minimum of the number of events that resulted in sudden rapid uplift because platform preservation is also a function of rising holocene sea level at present rates and patterns of net surface uplift are better constrained than the timing and magnitude of paleoearthquakes periods of rapid holocene emergence also are identified as far south of the area of 1992 uplift and the mendocino fault as 30 km along the unlocated san andreas fault these also might be associated with coseismic uplift based on new mapping of active faults in the region it is proposed here that this uplift is the result of multiple discontinuous thrust and strike slip fault segments which distribute plate boundary deformation along a restraining bend at the termination of the san andreas fault this interpretation is consistent with the fact that a single prominent strike slip fault has not been identified in the mendocino triple junction region while several small reverse faults crossing holocene deposits and geomorphic surfaces have been mapped and dated

neogene stress field in sw japan and mechanism of deformation during the sea of japan opening we present new structural data from sw japan and discuss the mechanism of deformation during the opening of the sea of japan we studied the miocene basins at the southern margin of the sea of japan northern coast of sw japan and of the median tectonic line mtl by means of fault slip analysis to determine stress field directions during the opening of the sea of japan in early and middle miocene time on the southern margin the stress field was extensional or transtensional with a nw se trending extension direction the mtl was a normal fault in shikoku during early middle miocene and probably a normal fault with a left lateral component in central japan before having been strained by the collisions of the tanzawa and izu blocks with central japan we combine our results with published data for the sea of japan area and show that early and middle miocene stress field directions are remarkably consistent on the eastern southern and western margins of the sea of japan with hmax trending ne sw and hmin trending nw se the stress regime is transpressional or transtensional on the eastern and western margin and almost purely extensional on the southern margin this stress field distribution is in agreement with the model of the opening of the sea of japan in an extensional transfer zone between two n s right lateral strike slip zones proposed by jolivet et al 1991 analogue modelings and kinematic reconstructions showed that this model accounts for 20 to 30 of clockwise rotation in sw japan while paleomagnetic rotations reached 40 to 50 during the opening we present structural data showing that sw japan was strained during the rotation and did not behave as a rigid block our observations suggest that rotations of small blocks may have occurred we propose that sw japan has been sheared between the right lateral strike slip zones which bound the sea of japan and that the missing 10 to 30 of rotation are to be found in its internal deformation in our model the mtl is a normal fault with a strike slip component rotating in a right lateral shear zone

retrodeformation analysis of the quaternary fault in the southeastern korean peninsula abstract the suryum fault f1 with subsidiary branches f2 3 varies in strike from n40 e to n14 e and in dip from

on the possibility of a widespread remagnetization of pre oligocene rocks from northeast japan and the miocene rotational opening of the japan sea abstract we present new paleomagnetic results from the well dated miyako cretaceous sediments 100 110 ma from northeast japan these results combined with those of tosha 1 yield an in situ characteristic directiond 321 i 54 5 95 4 5 n 14 sites reduced to a reference point at 40 n 142 e this direction is found to coincide with that of most older plutonic and sedimentary rocks of devonian to lower cretaceous age it is also identical with the westerly pre folding direction which is preserved in many oligocene 20 40 ma formations from northeast japan 1 2 in contrast all recent formations 0 17 ma have been magnetized in the direction of the present axial dipole field only the oligocene and miocene results appear to be primary or at least pre folding the miyako sulfide bearing sediments and lower cretaceous 110 125 ma magnetite bearing granites could either still bear a primary magnetization or be completely remagnetized by a low temperature chemical event evidence for such events is now found in many places and as close as south korea available data constrain the oligo miocene history of northeast japan and indicate at least20 30 counterclockwise rotation with respect to mainland asia during the opening of the sea of japan on the other hand the pre 40 ma history of northeast japan is not well constrained and three models are proposed which are compatible with various interpretations of the data none of them can presently document pro oligocene motion of northeast japan with respect to asia the most economical model implies widespread remagnetization we conclude that because of the scarcity of well tested primary magnetization directions the classical bending of the japanese islands rests on weaker grounds than generally realized and that no pre 40 ma apparent polar wander path of the japanese islands can safely be proposed

buried marine cut terraces and submerged marine built terraces the carchuna calahonda coastal area southeast iberian peninsula abstract the carchuna calahonda coastal area is located between the onshore betic cordillera and the alboran sea its onshore sector is formed by detrital sediments that cover a metamorphic basement mostly composed of marbles contiguous to an offshore shelf setting new onshore gravity data allow us to characterize the location of flat marine cut terraces carved into the metamorphic bedrock which are covered by detrital sediments in addition multibeam bathymetry data 3 5 khz and sparker reflection seismic profiles reveal offshore flat features linked to marine terraces that are related with the onshore buried marine cut terraces gravity data are newly used to detect marine cut terraces covered by sediments enhancing the integration of onshore and offshore data the marine terraces are distinguished based on the relative sea level trend regressive versus transgressive and on the dominant sedimentary regime erosional versus depositional these data help constrain the ages of the marine terraces younger than 150 ka using available late quaternary sea level curves although previous geodetic research suggests a rapid sinking of the carchuna calahonda coast the heights of the marine cut terraces and depositional terraces are mainly driven by sea level changes not tectonics

use of a new 10be and 26al inventory method to date marine terraces santa cruz california usa marine terraces along active continental margins reflect the interplay between sea level oscillations and rock uplift well dated marine terraces record the timing of sea level highstands and delimit both uplift and geomorphic rates cosmogenic radionuclides provide a new tool for dating previously undatable terraces because the five marine terraces north of santa cruz california are capped by well developed soils formed in regressive marine sands both predepositional cosmogenic radionuclide inheritance and bioturbation of the profile must be accounted for we present a new cosmogenic radionuclide inventory method that uses the depth integrated cosmogenic radionuclide concentration to determine the terrace age this method yields terrace ages that correlate well with sea level highstands of marine oxygen isotope stages 3 5a 5c 5e and 7 the implied uplift rate is steady at 1 1 mm yr and is two to three times higher than rates suggested by earlier studies

miocene paleomagnetic results from southeastern korea paleomagnetic samples were collected from 25 sites of late oligocene to middle miocene age from southeastern south korea the mean direction obtained is d 39 4 i 46 2 with 95 9 5 which is statistically distinguishable from the present axial geocentric dipole field direction when combined with the previous reported results of eight sites from this region we get a mean direction d 40 1 i 47 4 95 7 9 for 33 sites of late oligocene to middle miocene age this direction yields an early neogene virtual geomagnetic pole of 56 5 n 215 2 e with an 95 of 7 9 discordant from the cretaceous reference pole for korea the paleomagnetic data suggest that portions of southeastern korea underwent a large clockwise rotation of about 40 during the neogene two large ne trending right lateral faults the yangsan fault and the dongnae fault fig 1 cut the study areas both these faults show evidence for recent activity in addition minor faults with similar trends to these major faults occur the observed deflections in paleomagnetic declinations were probably caused by rigid block rotations of crustal blocks in a right lateral shear system during the neogene the paleomagnetic directions for miocene aged rocks from southeastern korea and southwestern japan are similar in direction and magnitude this suggests that the cause of the rotations in both areas may be related to a similar tectonic event in this area during the neogene

luminescence dating of well sorted marine terrace sediments on the southeastern coast of korea abstract along the southeastern coastline of the korean peninsula well developed marine terraces are found at various elevations the ages of these terraces and the time of deposition of the terrace sediments are important to our understanding of the geological history of this area during the quaternary period and represent a unique record of the regional tectonic activity previous efforts to establish a chronology using optically stimulated luminescence osl methods have produced controversial results particularly because of stratigraphic inconsistency and poor reproducibility in this paper the application of osl dating based on the single aliquot regenerative dose sar protocol for quartz is investigated the dependence of equivalent dose on the preheat and cut heat temperatures thermal treatment of the regeneration and test doses respectively are examined linearly modulated luminescence signals from chemically cleaned quartz samples are used to identify the presence of a thermally unstable component with a large optical cross section component a which in part affects the ability to correct for sensitivity changes during measurements and thus the reliability of the equivalent dose estimates in some samples a higher heat treatment after the test dose is shown to improve our ability to measure a dose given in the laboratory before any heat treatment dose recovery test this higher temperature treatment effectively removes component a and hence improves sensitivity correction furthermore the samples were broadly divided into poorly sorted and well sorted based on field evidence the poorly sorted samples contain friable weathered gravel clasts which is a likely post depositional source of quartz grains in general these grains will not have been zeroed prior to deposition and so the poorly sorted samples are rejected from further age studies results obtained from the well sorted samples are reproducible at each sampling location and give ages grouping broadly into 50 70 and 110 120 ka but laterally discontinuous on a scale of tens of km our osl results for the younger group are supported by radiocarbon ages from overlying terrestrial deposits it is concluded that these results point to considerable tectonic activity in the southeast of korea during the late pleistocene

alternate senses of displacement along the tsushima fault system during the neogene based on fracture analyses near the western margin of the japan sea abstract the western margin of the japan sea is characterized by the existence of a n20 e trending transcurrent fault system in the korea strait between korea and kyushu this fault system called here the tsushima fault system played a major role during the opening of the japan sea during the tertiary in order to understand its displacement history we analysed the deformation recorded by neogene rocks exposed on the korea strait islands tsushima goto and hirado islands a synthesis of published stratigraphical and structural data together with our field observations reveals that two tectonic events occurred in succession in the study area an early miocene nw se oriented extension event i and a middle miocene nw se oriented shortening event ii two distinct families of fractures with contrasted stratigraphic occurrences have been recognized in the neogene rocks exposed on the korea strait islands and allow us to define and date the stress fields characterizing each tectonic event stress field i is of intermediate type the vertical axis is either 1 or 2 with a n45 e hmax and n135 e hmin and was active between 22 and 16 ma stress field ii is compressional the vertical axis is 3 with a n135 e hmax and a n45 e hmin and was active between 15 and 10 ma the trends of stress field i principal axes imply that the displacement along the tsushima fault system was dextral during the early miocene conversely the trends of stress field ii principal axes imply that the displacement along the same fault system was sinistral during the second half of the middle miocene the inferred displacement history agrees with 1 a pull apart model for the opening of the japan sea during the early miocene and 2 transition from tensional to compressional stress fields in the japanese arc and back arc region at the end of the middle miocene

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

a record of the blake event during the last interglacial paleosol in the western loess plateau of china abstract a high resolution record of the blake event has been obtained from a 40 m well dug in a loess section at jiuzhoutai in the city of lanzhou in the western loess plateau of china the paleomagnetic signal is principally carried by magnetite both in loess and paleosols the blake event is located at the boundary between paleosol s1 c of the last interglacial equivalent to mis 5e in deep sea records and loess l2 2 mis 5d and is characterized by a triple feature consisting of two short reversed intervals separated by a short normal interval the directional changes are abrupt as previously revealed in other records and suggest geocentric dipole field behavior before after and during the event but not necessarily during n r or r n transitions the age and duration of the event are estimated as between 119 97 and 114 47 kyr bp and 5 5 kyr respectively from thermoluminescence dating and astronomically tuned climate stratigraphy based on high resolution magnetic susceptibility

interpreting quaternary uplift rates at the mendocino triple junction northern california from uplifted marine terraces analysis of the altitudinal spacing of 14 flights of marine terraces indicates a spatial pattern of varying uplift rates that agrees with that determined from previously dated terraces for the past 3 81 ka and temporal changes in uplift rates from 1 m ka to 3 5 m ka that may reflect response to changes in tectonic regime during passage of the mendocino triple junction mtj a possible mechanism for regional uplift is growth of a slab window south of the mtj the region of most rapid uplift is 25 43 km south of the mtj immediately south of the northern boundary of the slab window the coastline is tilted upward to the south in the region directly above the southern edge of the subducted gorda plate at point delgada 55 km south of the present mtj where the northern edge of the slab window passes approximately 300 ka uplift rates have been 1 2 m ka for at least 330 ka more than 1 4 m y after passage of the southern edge of the subducted slab at the mendocino coast uplift rates have been less than 0 4 m ka for at least 330 ka

tectonic history of ulleung basin margin east sea sea of japan a geologic history analysis of an exploratory well drilled on the southern margin of the ulleung back arc basin east sea western part of the sea of japan reveals that tectonic force and sedimentary loading played a major role in the subsidence of the paleo ulleung basin where a thick clastic sequence was deposited during the neogene initial subsidence was most likely caused by a tectonic force related to the back arc rifting and spreading associated with convergent processes the southern margin underwent regional deformation uplift faulting and folding toward the late miocene this event was probably due to back arc deformation caused by changes both in plate motions and in subduction mode at the convergent zones

opening mode of the japan sea inferred from the palaeomagnetism of the japan arc the western edge of the pacific plate is marked by a chain of back arc basins stretching from the aleutians through japan and the philippines to new zealand most of the basins lie behind volcanic island arcs far from continents and are the result of extension of the oceanic lithosphere1 but the japan sea is bounded on one side by continental crust the sikhote alin and korean peninsula of the asian continent and on the other by an active arc with continental fragments it can thus be said to be associated more with continental rifting1 4 than with oceanic processes we report here palaeomagnetic data from the japan arc which indicate that since the early miocene north east japan has rotated counter clockwise through 47 around a vertical axis while south west japan has rotated clockwise through 56 refs 5 8 we attribute this differential rotation which took place concurrently between 21 and 11 myr ago to the back arc opening of the japan sea8 with a double door mode that is there are two fan shaped spreading basins facing each other such a fan shaped opening is probably peculiar to the geological phenomenon of rifting of a continental fragment from thick continental lithosphere

investigation of short period gravity waves with the lindenberg 482 mhz tropospheric wind profiler during four consecutive days in may 2001 convectively forced short period 6 45 min gravity waves were observed with a 482 mhz wind profiler which is continuously operated by the deutscher wetterdienst german weather service at the lindenberg observatory 60 km south east of berlin the objective of this campaign was to investigate onset and development of convectively forced gravity waves in the lower and middle troposphere the wave character could be unambiguously identified by simultaneous vertical wind and temperature measurements and their respective phase shift of 2 in accordance with previous findings convection waves were found to be generated at the top of the convective boundary layer they propagate predominantly horizontally with a slow but clearly recognizable vertical increase of wave activity the layer with significant wave activity reached the upper detection range at 7 0 km within a couple of hours on each of the observational days gravity wave activity started to decay after 16 utc with a slower rate than the simultaneously decaying forcing convection some wave activity remained during the night but at low amplitude levels the vertical wind energy component of the free atmosphere was found to be about 30 of the corresponding convective boundary layer cbl energy which is much more than previously reported values from numerical simulations the wavelet analysis of highly resolved wind profiler vertical velocity data t 16 s z 250 m in the boundary layer and free troposphere gives new insights into the temporal and vertical development of very short period convection waves through the troposphere at the cbl top a broad spectrum of wave scales with intrinsic periods between 6 and 45 min is generated with increasing height shorter scales t 13 min disappear and only longer ones remain wave trapping which is confirmed by vertically orientated phase lines is an important mechanism here copyright 2004 royal meteorological society

constraining the transgression history in the bohai coast china since the middle pleistocene by luminescence dating abstract three phases of transgression have been identified in the middle to late pleistocene sedimentary succession in the bohai sea northern china which is considered to be key information for understanding environmental evolution and marine terrestrial interaction in the east asia however the timing of these transgressions still remains controversial in this study luminescence dating was performed on a core drilled in the north bohai coast to establish a reliable chronological framework of the transgression regression cycles after validating the applicability of luminescence dating for the bohai sediments quartz optically stimulated luminescence osl and k feldspar post infrared ir irsl pirir signals with elevated temperatures at 150 225 and 290 c were employed for dating the sediment core the quartz osl signal used for the upper 25 m of the sediment core was well bleached yielding finite ages within ca 50 ka whilst the k feldspar pirir225 signal was also well bleached for the pleistocene samples with an extended dating limit to ca 300 ka the luminescence ages of ca 200 ka and ca 7 0 0 2 ka indicated that the lowermost and uppermost of three transgression units likely represent sea level highstand during marine isotope stages mis 7 and 1 respectively which were also evidenced by the consistency between the reconstructed palaeo topography elevation and the contemporaneous global mean sea level our luminescence ages of the second transgressive unit suggest it has a mis 3 origin being consistent with previous studies but this appears to be unlikely as the level of the unit is significantly above the interstadial sea level in the mis 3 further high resolution luminescence dating of the second transgression is thus required

fault slip analysis of quaternary faults in southeastern korea abstract the quaternary stress field has been reconstructed for southeast korea using sets of fault data the subhorizontal direction of the maximum principal stress 1 trended ene and the direction of the minimum principal stress 3 was nearly vertical the stress ratio 2 3 1 3 value was 0 65 two possible interpretations for the stress field can be made in the framework of eastern asian tectonics 1 the hmax trajectory for southeast korea fits well with the fan shaped radial pattern of maximum principal stress induced by the india eurasia collision thus we suggest that the main source for this recent stress field in southeast korea is related to the remote india eurasia continental collision 2 the stress field in korea shows a pattern similar to that in southwestern japan the origin for the e w trending hmax in japan is known to be related to the mantle upwelling in the east china sea thus it is possible that quaternary stress field in korea has evolved synchronously with that in japan we suggest further studies gps and in situ stress measurement to test these hypotheses

the quaternary marine terraces of santa cruz california evidence for coseismic uplift on two faults the coast parallel elevation pattern of marine terraces along 50 km of coast centered about santa cruz california provides an opportunity to assess the relative roles of candidate uplift mechanisms we assemble 130 existing latitude longitude elevation inner edge locations from three of these marine terraces to constrain elastic dislocation models of coseismic uplift uplift resulting from repeated oblique slip seismic events similar to the loma prieta earthquake m s 6 9 of october 17 1989 appears to explain well the portion of the terrace uplift pattern south of santa cruz depending on whether the lowest terrace is assumed to correspond to isotope stage 5c or 5e the calculated mean repeat time for loma prieta events is either 490 or 820 yr corresponding to either 4 1 or 2 4mm yr slip rates on the loma prieta fault residual uplift not explained by such events increases monotonically to the north toward ano nuevo where the san gregorio fault zone intersects the coastline we assess whether this residual uplift may result from repeated events on the san gregorio fault given only the strike of the san gregorio fault we use an extensive parameter search to determine the geometry of and the style of motion on the implied rupture plane that best explains this residual uplift the fault parameters that minimize the misfit between data and model imply activity of a moderately steep 70 north east dipping san gregorio fault that ruptures in oblique thrust slip from 15 km to the surface the thrust slip component dominates the uplift pattern resulting in uplift of the coastline from santa cruz northward these parameters match available geological geodetic and seismic data on the dip and sense of motion on strictures within the san gregorio fault zone the san gregorio fault has therefore been an active late pleistocene participant in north american pacific plate boundary motion we conclude that the complex pattern of uplift along this 50 km reach of coastline can be explained by coseismic mechanisms tied to san andmas bend related fault structures onshore and to the san gregorio fault zone offshore as both of these mechanisms result locally in considerable shore normal uplift gradients caution is warranted in applying common correlation techniques based solely on uplift rates in the assignment of terrace ages in this and other such settings in addition while it is tempting to use terrace culmination offsets as a means of estimating san andreas fault dextral slip rates we provide a formalism to determine under what conditions such calculations are meaningful we conclude that the terrace offsets along the santa cruz coastline result not from dextral slip on the san andreas but from differential indentation of the loma prieta uplift pattern by the various sea level highstand coastlines

lichenometric dating and the nature of the excavation of the huashan grottoes east china the present study aims to identify the timing of the huashan grottoes excavations using the lichenometric dating method a total of 96 maximum inscribed circle diameters of rhizocarpon geographicum growing on the ancient architectures and the walls of entrances are measured in the huashan grottoes area of southern anhui east china the results show that the period of the grottoes excavation is estimated to be 450 335 yr bp or the middle and late ming dynasty 1552 1667 ad the lichenometric dating results are also validated by a lithologic comparison of the grottoes and the surrounding ancient architectures as well as by the studies on the historical documents and the fragments of ancient porcelain in the grottoes furthermore we infer that the excavation of the inner grottoes might have lasted till the qing dynasty 1636 1912 ad because the lichens chosen for dating are mainly at the grottoes entrances the wider significance of this work is that it demonstrates for the first time lichenometric dating can be applied in the historical studies on the ancient architectures in east china with a relatively warm and humid climate

tectonic analysis of fault slip data sets using data that include the direction and the sense of motion on individual fault surfaces determined by slickenside lineations it is possible to reconstruct reduced stress tensors that correspond to the orientation of stress axes and to the ratio 2 3 1 3 between principal stress values 1 2 3 compression being positive no assumption is made concerning the orientation of fault planes relative to stress axes so that reactived faults are taken into account as well as newly created ones qualitative and quantitative methods for analysis of fault slip data were developed during the last 10 years the practical limitation of the methods and the necessity for critical field observations are emphasized these methods can be applied to focal mechanisms of earthquakes a more complex analysis of heterogeneous data sets involving an iterative separation of different stress systems is also discussed this analysis enables one to distinguish successive faulting events careful qualitative study in the field is in all cases essential

the analysis of last interglacial mis 5e relative sea level indicators reconstructing sea level in a warmer world the last interglacial mis 5e 128 116 ka is among the most studied past periods in earth s history the climate at that time was warmer than today primarily due to different orbital conditions with smaller ice sheets and higher sea level field evidence for mis 5e sea level was reported from thousands of sites but often paleo shorelines were measured with low accuracy techniques and in some cases there are contrasting interpretations about paleo sea level reconstructions for this reason large uncertainties still surround both the maximum sea level attained as well as the pattern of sea level change throughout mis 5e such uncertainties are exacerbated by the lack of a uniform approach to measuring and interpreting the geological evidence of paleo sea levels in this review we discuss the characteristics of mis 5e field observations and we set the basis for a standardized approach to mis 5e paleo sea level reconstructions that is already successfully applied in holocene sea level research application of the standard definitions and methodologies described in this paper will enhance our ability to compare data from different research groups and different areas in order to gain deeper insights into mis 5e sea level changes improving estimates of last interglacial sea level is in turn a key to understanding the behavior of ice sheets in a warmer world

recalibration of the yellow rhizocarpon growth curve in the cordillera blanca peru and implications for lia chronology abstract a new lichen dating method and new moraine observations enabled us to improve the chronology of glacier advances in the cordillera blanca peru during the little ice age lia our results reveal that an early lia glacial advance occurred around ad 1330 29 however a second major glacial advance at the beginning of the 17th century overlapped the earlier stage for most glaciers hence this second glacial stage dated from ad 1630 27 is considered as the lia maximum glacial advance in the cordillera blanca during the 17th 18th centuries at least three glacial advances were recorded synchronously for the different glaciers ad 1670 24 1730 21 and 1760 19 the moraines corresponding to the two first stages are close to the one in 1630 suggesting a slow recession of about 18 in the total length of the glacier from the lia maximum extent to the beginning of the 20th century the 24 glaciers have retreated a distance of about 1000 m corresponding to a reduction of 30 in their length this rate is comparable to that observed during the 20th century estimates of palaeo equilibrium line altitudes show an increase in altitude of about 100 m from the lia maximum glacial extension at the beginning of the 17th century to the beginning of the 20th century because long time series are not available for precipitation and temperature this glacial retreat is difficult to explain by past climate changes however there is a fair correspondence between changes in glacier length and the 18 o recorded in the quelccaya ice core at a century timescale our current knowledge of tropical glaciers and isotope variations leads us to suggest that this common tropical signal reflects a change from a wet lia to the drier conditions of today finally a remarkable synchronicity is observed with glacial variations in bolivia suggesting a common regional climatic pattern during the lia

contrasting styles and rates of tectonic uplift of coral reef terraces in the ryukyu and daito islands southwestern japan abstract coral reef terraces on kikai hateruma and yonaguni in the ryukyu islands on the eurasian lithospheric plate and those of kita daito and minami daito islands on the philippine sea plate indicate three distinct patterns of coral reef terrace formation and preservation primarily reflecting different uplift rates the kikai type which includes many terraces from oxygen isotope stages 5e to 1 is a result of high uplift rate of ca 1 8 m kyr on the fore arc rise of a chilean type subduction zone arcward westward tilting and faulting are also characteristic of the kikai type the hateruma type is characterized by two coral reef terraces younger than the stage 5e terrace and they are arranged in a concentric annular pattern slow uplift rate of ca 0 3 m kyr adjacent to a mariana type subduction margin is typical of the hateruma type the emergence of kikai and hateruma islands is recent younger than isotope stage 5e and 7 respectively reflecting the active deformations of the leading edge at the overriding eurasian plate in the daito type atolls surrounded by fringing reefs have been uplifted very slowly less than 0 05 m kyr but over a time period of at least several million years slow uplift and long history of daito type islands is the result of up bulging of the philippine sea plate as it migrates toward the ryukyu trench

coastal uplift in continental collision plate boundaries data from the last interglacial marine terraces of the gibraltar strait area south spain abstract the spatial height analyses of deposits belonging to isotopic substages 5e and 5c indicate the occurrence of differential uplift in the gibraltar strait area maximum mean uplift rates do not reach values of 0 2 mm year displaying a gentle deceleration from 0 15 to 0 10 mm year for the last 128 ka maximum estimated rates are recorded in the central sector of the gibraltar strait the combined analysis of the accumulated vertical movements before and after iss 5c indicates that differential uplift is accommodated along ne sw sinistral and nw se dextral mostly inherited strike slip fault systems separating coastal segments of contrasting uplifting subsiding behaviour the occurrence of inversions in the relative vertical offsets along some of these faults arises when this combined analysis is performed a model of asymmetric pure shear defined by these two fault systems generated in response to the roughly n s convergence between the african and eurasian plates can explain the recorded uplift patterns in this transpressive setting generated by the africa eurasia continental collision the recent convergence 4 mm year is mostly released by shear processes and subsidiary e w horizontal extension whilst the recorded coastal uplift only represents a low percentage of the recent convergence rates

possibility of the late holocene uplift in the southeastern coast of yeongil bay korean peninsula evidence from an exposed sea cave abstract marine terraces have developed intermittently along the southeastern shore of yeongil bay on the korean peninsula these terraces have been classified into four levels 4 5 14 15 25 27 and 35 m above sea level three sea caves formed in the cliffs of the 26 m marine terrace on the headland one of these caves is filled with sediments 3 4 m thick consisting of well sorted beach pebbles and sand or disorganized ignimbrite breccia the uppermost sediments dating to 1680 1820 at ca 4 m above the present sea level may indicate a former shoreline according to the historical earthquake catalog of the korean peninsula the three largest earthquakes mw 6 2 were recorded in 1643 and 1681 the catalog suggests that two earthquakes in 1643 were felt in the southern area of the korean peninsula in locations such as hapcheon daegu andong kimhae and ulsan the 1681 yangyang earthquake caused shaking over the entire korean peninsula and is thought to have been korea s largest historical earthquake we concluded that 4 m uplifting of the sea cave beach sediments could be explained by the highest seismicity and the three largest historical earthquakes in the 1600s it is believed that the 1681 ce main earthquake including its foreshocks and aftershocks resulted in reactivation of the ocheon fault which may be the main cause of sea cave uplifting on the masan ri coast

tectonic setting of western pacific marginal basins abstract global kinematics as well as magnetic anomalies of marginal basins with continental geology and paleomagnetic data as additional constraints are used to present a set of reconstructions of the western pacific marginal basins between 56 ma and the present at key periods 56 43 32 20 12 and 3 ma our model accounts for the rapid motion of exotic terranes along the whole of the western pacific convergent zone marginal basins appear to open in a great variety of tectonic settings the two extreme examples being the mariana trough where trench suction may be the predominant driving force and the south china sea where intracontinental deformation appears to be the major mechanism the study of marginal basins is a 3 d problem which must take into account the whole tectonic context subduction related tectonics in cross section and upper plate deformation in map view and not only a 2 d problem the classical trench arc back arc problem

crustal scale strike slip deformation in hokkaido northern japan abstract field surveys in hokkaido reveal that the entire tectonic belt in northern japan was a right lateral shear zone from eocene to middle miocene time this zone of deformation can be followed northwards in sakhalin for more than 2000 km and formed at the same time as the opening of the japan sea a thrusting component during the strike slip deformation and later deformation stages led to the uplift of the deep parts of the shear zone exposing a complete section through the upper crust the stress field inferred from the analysis of fault sets is consistent with the non coaxial deformation observed in the deeper ductile parts of the shear zone there is a transition from west to east across the width of the belt 100 km from en echelon folds thrusts and nappes at upper structural levels through the brittle ductile transition with an incipient vertical schistosity into ductile deformation with a vertical foliation and metamorphic recrystallization in the amphibolite facies deep parts of the crust granulites were uplifted and retrogressed during the strike slip movement fault set analysis together with data concerning the direction and sense of nappe emplacement imply that thrusting west of the ductile deformation zone occurred during the strike slip deformation minor flat lying structures coexist with vertical pure strike slip structures this study and previous ones reveal a crustal scale half flower structure with superficial thrusting associated with a deep narrow ductile zone with a high gradient of deformation and temperature

coastal neotectonics in southern central andes uplift and deformation of marine terraces in northern chile 27 s abstract neotectonic observations allow a new interpretation of the recent tectonic behaviour of the outer fore arc in the caldera area northern chile 27 s two periods of deformation are distinguished based on large scale neogene to quaternary features of the westernmost part of the coastal cordillera late miocene to early pliocene deformations characterized by a weak ne sw to e w extension is followed by uppermost pliocene nw se to e w compression the middle pleistocene to recent time is characterized by vertical uplift and nw se extension these deformations provide clear indications of the occurrence of moderate to large earthquakes microseismic observations however indicate a lack of shallow crustal seismicity in coastal zone we propose that both long term brittle deformation and uplift are linked to the subduction seismic cycle

amount of clockwise rotation of southwest japan fan shape opening of the southwestern part of the japan sea abstract paleomagnetic measurements have been carried out on welded tuffs ranging in age between 58 ma and 112 ma from yamaguchi and go river areas in the central part of southwest japan the new data together with those of younger igneous rocks published previously define the change of paleomagnetic field direction during the late mesozoic cenozoic period for southwest japan the paleomagnetic direction from this area has pointed 56 3 clockwise from the expected field direction estimated from apwp apparent polar wandering path of the whole of eurasia during the period between 100 and 20 ma in comparison with the expected one from the eastern margin of eurasia korea china siberia the cretaceous field direction of southwest japan shows the clockwise deflection by 44 49 these results establish that while the eastern margin of eurasia including southwest japan was rotated more or less with respect to the main part of eurasia during last 100 ma southwest japan was rotated clockwise through more than 40 with respect to the eastern margin of eurasia since 20 ma the large amount of rotation for southwest japan implies that it is rotated by an opening of the southwestern part of the japan sea which widens northeastward fan shape opening the tectonic feature of southwest japan and the japan sea is analogous to that of corso sardinia and the ligurian sea in the mediterranean indicating that the fan shape opening is a specific feature of the rifting of the continental sliver at the continental rim

gravity waves above a convective boundary layer a comparison between wind profiler observations and numerical simulations wind profiler observations and three dimensional numerical modelling are used to investigate gravity waves generated over convectively active boundary layers on 12 and 13 may 2001 at lindenberg germany the results illustrate the importance of changes in the background wind and stability profile in influencing the vertical propagation of the gravity waves the resultant changes in vertical propagation cause the dominance of relatively long wavelength long period waves at high levels and the dominance of relatively short wavelength short period waves near the top of the convective boundary layer there are important differences between the two days in the wave propagation characteristics due to subtle changes in the background flow conditions copyright 2007 royal meteorological society

convection waves observations of gravity wave systems over convectively active boundary layers widespread gravity wave systems have been found to exist over convectively active boundary layers cbls in the presence of vertical wind shear in contrast to mountain waves these convection waves occur over flat terrain and are ubiquitous over fields of shallow fair weather cumuli or clear air thermals they extend vertically to at least 9km a m s l probably to the tropopause first discovered by glider pilots as thermal waves they have now been systematically investigated by research aircraft during the ncar convection wave project which also incorporates an effort in numerical simulation the flight results are reported in this paper while the numerical simulations are described in a companion paper typical wavelengths of convection waves were found to range from 5 to 15 km average 9 km and typical vertical motion amplitudes from 1 to 3 m s 1 in all cases vertical wind shear exceeded 3 10 3s 1 under these conditions cloud tops were measured to move with relative velocities of 8 to 10 m s 1 against their environment hence they present an obstacle to the surrounding airflow the analogy to mountainous obstacles launching gravity waves into the atmosphere is suggestive and borne out by the aforementioned numerical simulations which describe this process step by step the interaction between the cbl and the overlying stable layers is studied by spectral and cross spectral analysis of aircraft data including coherence and phase relations between wave motions and cloud population underneath consideration is given to other potential sources of the observed gravity waves at this stage the conclusions of our pilot study may be considered tentative some implications for further research are also discussed

submarine geology and post opening tectonic movements in the southern region of the sea of japan abstract the submarine geologic structure of the southern region of the sea of japan was analyzed on the basis of seismic reflection profile data and bottom samples the seismic reflection patterns depict sedimentary layers with well developed onlap and toplap terminations and truncations by submarine erosion the planes marked by series of onlap toplap and erosional truncations enabled us to define three stratigraphic groups composed of six formations in this region they are the kasumioki group the hamasakaoki group and the tottorioki group in ascending order detailed analysis of the seismic reflection profiles reveals subtle structures of these sedimentary units the oldest kasumioki group is folded and faulted forming submarine ridges the hamasakaoki group mainly occurs in the depressions between these ridges the youngest tottorioki group covers widely both of the older formations with a pronounced marine onlap fossil evidence indicates that the depositional ages of the kasumioki group the hamasakaoki group and the tottorioki group are early miocene to earliest pliocene late early to late pliocene and late pliocene to holocene respectively these observations provide the basis to understand two main structural features in this region 1 e w trending folds and 2 northwestward tilting blocks the former construct a fold zone composed of two to four ranges of anticlines that have steeper southern flanks truncated by reverse faults the latter are shown by slightly inclined floors formed by submarine erosion step like asymmetric basins bounded by ne sw trending reverse faults and onlap toplap sedimentation patterns the lateral change in bed thickness sedimentation patterns and age of submarine sediments indicate that the e w trending folds were formed in the early middle or late miocene to the early pliocene by n s compression whereas the northwestward tilt blocks were formed in the late early to late pliocene by nw se compression the sedimentary records in this region dictate an abrupt change in tectonic setting in the late early pliocene this change is interpreted to show that the sea of japan has been closing since then due to either the reactivation of the amurian plate or the directional change of the philippine sea plate motion

lichenometric dating of landslide episodes in the western part of the polish flysch carpathians abstract landslides are common in the polish part of the flysch carpathians they are controlled mostly by lithology and tectonics of the bedrock and by climate they are a major factor of slope transformation rock cliffs within deep landslides are overgrown with lichen thalli of the rhizocarpon genus so these cliffs may be dated using lichenometry this paper presents the basics of lichenometry as well as its applications in geomorphological research in poland and worldwide also presented are results of lichenometric dating of landslide rockfall walls in the western part of the polish flysch carpathians the study helps to identify landslide episodes from historical times the results obtained indicate that on the slopes studied there coexist several generations of landslide rockfall forms of various age including recent and active ones

late pleistocene and holocene glaciation of the fish lake valley northeastern alaska range alaska we reconstructed a chronology of glaciation spanning from the late pleistocene through the late holocene for fish lake valley in the north eastern alaska range using 10 be surface exposure dating and lichenometry after it attained its maximum late wisconsin extent the fish lake valley glacier began to retreat ca 16 5 ka and then experienced a readvance or standstill at 11 6 0 3 ka evidence of the earliest holocene glacial activity in the valley is a moraine immediately in front of little ice age lia moraines and is dated to 3 3 3 0 ka a subsequent advance culminated at ca ad 610 900 and several lia moraine crests date to ad 1290 1640 1860 and 1910 our results indicate that 10 be dating from high elevation sites can be used to help constrain late holocene glacial histories in alaska even when other dating techniques are unavailable close agreement between 10 be and lichenometric ages reveal that 10 be ages on late holocene moraines may