shear fracture patterns and connectivity at geometric complexities along strike slip faults shear fracture patterns and connectivity at geometric complexities such as echelon fault steps and fault bends along strike slip faults are investigated by simulating shear fracture propagation paths using a displacement discontinuity boundary element method together with a maximum distortional strain energy density criterion it is shown that shear fracture patterns and connectivity depend on the specific geometric configurations the applied stress orientations and the coefficient of friction for a given initial configuration of the major faults the subsequent patterns of the associated shear fractures and their linkage can be predicted if the remote state of stress and the coefficient of friction are known the analyses of fault geometries commonly encountered in nature have important implications for evaluating the effect of faults on fluid flow and earthquake hazards associated with the geometric complexities along strike slip faults in the upper crust

geostrophic circulation or shallow marine turbidity currents the dilemma of paleoflow patterns in storm influenced prograding shoreline systems abstract in ancient storm influenced prograding shoreline sequences sole marks mainly tool marks from hummocky crossstratified storm deposits are commonly oriented normal to paleoshoreline and the trend of paleobathymetric contours in the basin asymmetrical tool marks typically indicate flows directed offshore several workers have attributed their formation to storm generated shallow marine turbidity currents this interpretation conflicts with observations from modern shelves where storm driven circulation generally is geostrophically balanced and time averaged bottom currents approximately parallel bathymetric contours and the local shoreline the resolution of these apparently conflicting observations may lie in the realization that tool marks and many other small paleoflow indicators form almost instantly as the result of instantaneous flow conditions very near the bed beneath storm generated flows in the shallow ocean instantaneous and time averaged characteristics of the bottom boundary layer generally exhibit little similarity storm generated tool marks are formed by the movement of large tools within the thin less than 1 m inner boundary layer resulting from the superimposition of waves and currents the orientation of the peak instantaneous shear stress moving large tools under such combined flows mainly reflects wave orbital motions which typically are normal to shore the magnitude of stress is great y increased in the offshore direction and decreased in the onshore direction by superimposition of a steady current with an offshore component of flow but the direction of stress is only slightly affected in ancient storm influenced sequences therefore shore normal tool marks generally were not formed by turbidity currents rather their orientation is best attributed to shoaling waves approaching the coast at a very high angle asymmetrical tool marks are directed offshore due to enhanced shear stress on the offshore stroke of waves superimposed on a geostrophic current with an offshore flow component tool marks do not reflect the time averaged bottom flow direction in fact they provide almost no information concerning steady bottom currents in contrast high angle cross beds formed in coarser sediment by the migration of dunes and sandwaves although relatively rare in offshore storm deposits generally reveal approximately shore parallel flows in ancient systems cross beds closely reflect the time averaged flow direction in the outer boundary layer of a geostrophic current for three reasons 1 the net transport direction for sand moving as bed load beneath a combined flow lies between the directions of peak instantaneous shear stress and time averaged shear stress 2 large ripples disrupt the thin inner boundary layer and 3 long time intervals relative to wave induced velocity oscillations are required to form large ripples

the mathematics of early diagenesis from worms to waves the changes that sediments undergo after deposition are collectively known as diagenesis diagenesis is not widely recognized as a source for mathematical ideas however the myriad processes responsible for these changes lead to a wide variety of mathematical models in fact most of the classical models and methods of applied mathematics emerge naturally from quantification of diagenesis for example small scale sediment mixing by bottom dwelling animals can be described by the diffusion equation the dissolution of biogenic opal in sediments leads to sets of coupled nonlinear ordinary differential equations and modeling organisms that eat at depth in the sediment and defecate at the surface suggests the one dimensional wave equation while the effect of waves on pore waters is governed by the two or three dimensional wave equation diagenetic modeling however is not restricted to classical methods diagenetic problems of concern to modern mathematics exist in abundance these include free boundary problems that predict the depth of biological mixing or the penetration of o2 into sediments algebraic differential equations that result from the fast reversible reactions that regulate ph in pore waters inverse calculations of input functions histories and the determination of the optimum choice in a hierarchy of possible diagenetic models this review highlights and explores these topics with the hope of encouraging further modeling and analysis of diagenetic phenomena

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

swaley cross stratification in medium to coarse sandstone produced by oscillatory and combined flows examples from the proterozoic kansapathar formation chhattisgarh basin m p india abstract the proterozoic kansapathar formation is the topmost unit of the siliciclastic chandarpur group of rocks which records a fluvial to marine transition and comprises a fining upwards transgressive succession overlain by a coarsening upwards prograding succession the kansapathar formation around panduka m p is composed of medium to coarse grained well sorted quartzarenite and is replete with swaley cross strata scs trough cross strata and other structures of intermediate morphology in laterally continuous exposures scs are more common in the northeastern part of the study area whereas trough cross strata are more dominant in the southwestern part we have recognised the scs on the basis of the stratal geometry originally described by leckie and walker 1982 scs occur as nested sets of elliptical swales which are commonly symmetrically filled the trough cross strata are variable in scales and dominantly sw directed the major axes of swales show a strong nnw sse preferred orientation orthogonal to the orientation of trough cross strata and at a low angle to the shoreline orientation determined from the megaripple orientation in the immediately underlying unit scs described herein in contrast to many examples reported from elsewhere formed in medium to coarse sand and the maximum inclinations of their lower bounding surfaces and of the infilling laminae are greater than those of fine grained hummocky cross strata hcs and scs this is explicable since medium to coarse grained sediments did not experience significant suspension transport and thus the development of low angle lamination was suppressed the symmetrically filled swales do not show any evidence of lateral migration and might have been formed by bidirectional oscillatory flow the trough cross strata could have been formed by translatory current dominated combined flow the spectrum of structures may owe their origin to symmetrical oscillatory flow transforming into asymmetric flow during onshore propagation of waves this is expected to be common in shoreface environment the spatial variation in relative frequency of occurrence of various types of cross strata is also consistent with the palaeogeographic reconstruction of the study area the trough cross strata seem to be more common towards the constantly shifting sands of nearshore thus the relative frequency of trough cross strata and scs has been used as a clue to determine relative proximity to shoreline

vertical distribution of feeding and particle selective transport of 137cs in lake sediments by lumbriculid oligochaetes lumbriculid oligochaetes are an important member of the conveyor belt deposit feeding species responsible for advective reworking of profundal sediments in the great lakes these threadlike worms ingest sediments over a range of depths 0 5 cm and deposit gut contents at the sediment surface this action results in a depth dependent particle advection rate which can be related to the distribution of their feeding in this study two replicate microcosms of rectangular cross section 3 5 cm containing evenly spaced 1 cm thin layers 0 5 mm of sediment labeled with gamma emitting 137cs were inoculated with the lumbriculid stylodrilus heringianus at a density of 7 9 104 m 2 10 c the subsequent amount of tracer lost from each layer as well as the downward movement of the layers were determined by peiodically scanning the length of the cells with a well collimated gamma detector system during the course of the 600 hour experiment 137cs activities decreased only in layers between 0 and 6 cm depth these decreases were accompanied by the appearance of a new layer at the sediment surface between 80 and 90 of the activity lost from the underlying layers appeared in the emergent surface peak thus indicating that subsurface defecation was minor aspect of conveyor belt transport decreases in 137cs activity within layers were consistent with first order kinetics with a maximum loss rate of about 0 08 hour 1 the vertical distribution of the rate constant was very nearly gaussian with the maximum at 3 3 cm and a spread sd of 1 4 cm the rate of layer burial decreased monotonically but nonlinearly with sediment depth from an extrapolated surface value of about 1 8 10 2 mm h 1 a model based on conservation of mass was developed which relates the tracer feeding distribution to the velocity distribution assuming that the distribution of mass removed through feeding was proportional to the amount of tracer removed the model takes rigorous account of depth dependent porosity and provides an excellent description of the velocity distributions if the transfer of 137cs is taken to be 1 67 times the mass transfer rate this factor termed the feeding selectivity factor is attributed to the selection of fine particles by worms and is important in models describing trace and contaminant diagenesis in sediments reworked by conveyor belt species

the use of distinct disciplines to investigate past earthquakes abstract the investigation of past earthquakes can be approached in many different ways with a large variety of methods and techniques this is mainly due to the complexity of this natural phenomenon in both its genetic aspects and consequential ones in the present note we briefly analyse the peculiarities of instrumental seismology historical seismology archaeoseismology and earthquake geology but especially we emphasise the major differences among these four distinct approaches in order to better define and clearly separate these disciplines in terms of appropriate tools to be applied and possible outcomes to be expected an alternative point of view is proposed based on the source of information and not on a chronological distribution as commonly accepted in the literature although multidisciplinarity is a common approach for investigating past earthquakes each one of the discussed disciplines has its own peculiarities advantages and limitations and researchers should be aware of this

a palaeoseismological and geoarchaeological investigation of the eliki fault gulf of corinth greece abstract palaeoseismological and morphotectonic analyses enable us to define a 400 m wide actively deformed zone associated with the active eliki normal fault central greece bounded on the south by a second order fault and on the north by a composite and prominent fault scarp this scarp is further analysed by trenching based on colluvium stratigraphy displacement of distinct horizons and deposition of sedimentary layers three faulting events have been identified along four fault strands affecting unconsolidated sediments in the trench the two younger events with throws of 0 93 and 1 37 m respectively the third event with a throw of 0 44 m and the penultimate 373 bc event suggest a variable seismic history the entire alluvial plain of the kerynitis and vouraikos rivers which cross the eliki fault has subsided at a rate of 1 4 mm year resulting in the burial of the late hellenistic roman occupation horizons under 3 m of fluvial and colluvial sediments in places extension in the broader area is accommodated by the seismically active eliki and egion faults structural and palaeoseismological analysis of those two faults indicates that they accommodate 1 5 mm year or about 10 of the geodetically estimated extension of up to 13 mm year

marine and nonmarine deposition in a long term low accommodation setting an example from the middle pleistocene qm2 unit eastern central italy abstract facies anatomy and large scale stratigraphic organization of mid pleistocene strata qm2 unit exposed near the town of ortona eastern central italy have been defined through an integrated outcrop and subsurface dataset and record sedimentation within a long term low accommodation setting the studied interval can be subdivided into nine facies associations reflecting a range of continental marginal marine nearshore and innermost shelf environments and contains a well preserved record of high frequency relative sea level changes in the form of a stack of three unconformity bounded sequences each of the three sequences designated qm23 qm22 and qm21 from oldest to youngest consists of a specific subset of the nine identified facies associations as a function of preserved depositional systems and systems tracts typically the following architectural elements occur in ascending stratigraphic order i a basal unconformity molded by fluvial incision and subaerial exposure during sea level fall and shoreface erosion during subsequent rise ii a maximum regressive surface which is coincident with the sequence boundary iii a transgressive systems tract including braided river conglomerates and floodplain fines within the confines of an incised valley palustrine carbonates and back barrier lagoon mudstones and a deepening and fining upward shoreface to offshore transition facies succession bounded at the base by a wave ravinement surface iv a sharp regressive surface of marine erosion produced by shoreface incision during relative sea level fall and v a prograding downstepping and offlapping sharp based lithofacies assemblage of either beach conglomerates or sandstones ascribed to the falling stage systems tract overlain by a rooted paleosol marking subaerial exposure sequences were deposited on the uplifting palaeo adriatic shelf in response to repeated high frequency and high amplitude eustatic changes in sea level that would promote the creation of accommodation space by subtracting space to deposition the contemporaneous regional uplift of the basin margin may be accounted for the shingled downstepping configuration of individual sequences to form a falling stage sequence set of a larger composite sequence in dip view the erosional contact at the base of the qm2 falling stage sequence set is a composite regressive surface resulting from the downdip convergence and amalgamation of multiple erosional surfaces produced by the progressive basinward translation of successive sequences results from this study have direct implications for the oil and gas field development and exploration when making predictions of reservoir and seal geometries within shallow marine marginal marine and nonmarine sediments emplaced in similar long term limited accommodation settings

plutonium and210pb distributions in northeast atlantic sediments subsurface anomalies caused by non local mixing abstract the depth distributions of 210 pb and 239 240 pu measured in a suite of box cores collected from water depths of 4000 5000 m in the northeast atlantic ocean exhibit pronounced subsurface maxima caused by sediment reworking by benthic infauna small scale spatial heterogeneity in bioturbation rates is indicated by large differences in tracer profiles from duplicate cores separated only by a few centimeters 210 pb and 239 240 pu activity distributions from each subcore exhibit a high degree of correlation and most tracer profiles exhibit one or more subsurface maxima one dimensional biodiffusion analogue models do not adequately simulate the principal features of this data set however an inverse conveyer belt mixing model which simulates subsurface egestion or a functionally equivalent process of surficial material which is enriched both in organic debris and radioactive tracers can reproduce the subsurface tracer maxima single event and continuous subsurface egestion models have been formulated and solved for different feeding rates and background biodiffusive fields the single event model provides a better fit to the data and in particular ensures the observed high degree of correlation between the 210 pb and 239 240 pu activity profiles regardless of the different tracer input functions the most likely candidate responsible for subsurface tracer egestion is a large infaunal worm of the phylum sipunculida which dominates the biomass below a depth of 3 cm

luminescence dating of quaternary sediments recent advances duller geoffrey 2004 luminescence dating of quaternary sediments recent advances journal of quaternary science 19 2 pp 183 192 rae2008

dating san andreas fault earthquakes with lichenometry regionalrockfalleventsinthesierranevadaofcaliforniaare caused by distant earthquakes on the northern and southern san andreasfaultaswellasbylocalearthquakes lichenometricdating of synchronous pulses of rockfalls that are presumed to be caused by five historical earthquakes suggests an accuracy of 2 2 3 5 yr 95 confidence level for dating young events comparison of lichenometric ages for prehistorical rockfalls with precise radiocarbon ages of surface rupture times at the pallett creek and wrightwood paleoseismology sites indicates that earthquakes on the southern san andreas fault caused rockfalls 200 to 400 km to the north a major rockfall event at about a d 1690 supports the fumal et al 1993 model for a san andreas fault earthquake that was not detected at pallett creek the a d 1690 event in the chronology indicates that the earthquake recurrence interval was shorter and that the degree of clustering of times of earthquakes was less on the mojave segment of the san andreas fault than previously thought

mixing sedimentation rates and age dating for sediment cores abstract analytic solutions to the advection diffusion equation useful as a guide for the interpretation of mixing sedimentation rate and age dating effects in sediment cores have been derived various simplified mixing models appropriate to 14 c and 210 pb measurements have been considered the emphasis has been on a discussion of the various interrelations and dependencies among the mixing coefficient sedimentation rate and radioactive decay constant parameters in determining the 14 c and 210 pb concentrations as a function of depth porosity variations within the sediment column are also considered and the transformed advection diffusion equation including porosity effects is derived

exploratory flow duct experiments on combined flow bed configurations and some implications for interpreting storm event stratification abstract experiments were conducted to define equilibrium combined flow bed configurations developed under a wide range of oscillatory uo and unidirectional uu velocity components with a constant oscillation period of 8 5 sec and median grain size of 0 09 mm in the range of flows studied uo 0 0 80 m sec uu 0 0 25 m sec the bed phases are no movement small 2d ripples small 3d ripples large 3d ripples and plane bed small 2d ripples are stable at low uo and uu by increasing either velocity component the plan view bed configuration becomes progressively less regular as small 3d ripples develop small 3d ripples are stable at low to moderate uo and a wide r nge of uu under purely oscillatory flow as uo increases beyond about 0 40 m sec large scale hummocky bed forms become stable when a unidirectional component is applied these bed forms quickly develop a downstream asymmetry and generally move in the direction of uu the dip angles of the lee flanks increase with increasing uu although they remain less than the angle of repose at high oscillatory velocities uo 0 70 0 80 m sec plane bed is the stable bed phase when uu 0 05 m sec much hummocky cross stratification shows a preferred dip direction of the coset laminae our experiments support the idea that such cross stratification is produced by combined flow the large 3d ripples produced at high oscillatory velocities and small to moderate unidirectional velocities would presumably generate what might be called anisotropic hummocky cross stratification if we had been able to aggrade the bed during the runs this would be the case even in dominantly oscillatory flow the experiments show that even a weak unidirectional current of several centimeters per second superimposed upon a strong oscillatory flow results in bed forms that move predominantly in a single direction and that leave sets of laminae that dip predominantly in that direction in runs at large uo the purely oscillatory large scale bed forms were quickly planed off as uu was increased from zero but a series of almost stationary gentle undulations on the bed surface persisted for indefinitely long times where the original topographic highs were situated even at the highest unidirectional flow investigated 0 25 m sec this suggests a possible origin for the gentle undulation observed in cretaceous parallel laminated shallow marine sandstones described by arnott 1987 1988 with spacings up to a few meters and heights not much more than a centimeter

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

archeological and pedological evidence for large prehistoric earthquakes in the new madrid seismic zone central united states prehistoric liquefaction features have been identified by careful observation of their structural and stratigraphic relations to native american occupation horizons and their subtle soil characteristics the ages of these liquefaction features have been estimated from radiocarbon dating of wood associated with the features and native american artifacts found within bounding occupation horizons at three sites near blytheville arkansas in the central part of the new madrid seismic zone one sand blow crater formed between a d 800 and 1400 two sand blow deposits formed between a d 800 and 1670 and three possibly four sand dikes formed since 4035 b c where not found in association with native american occupation horizons and artifacts prehistoric liquefaction features can be difficult to distinguish from features that formed during the great new madrid earthquakes of a d 1811 and 1812 this raises the possibility that prehistoric liquefaction features may have been misinterpreted during previous studies in the area nevertheless a paleoearthquake chronology is beginning to emerge for the new madrid seismic zone our findings are consistent with paleoseismological studies in the northern part of the seismic zone and suggest a recurrence interval of hundreds of years for earthquakes large enough to induce liquefaction in this region m 6 4 by mapping the age distribution of liquefaction features a more accurate assessment of the long term earthquake potential of the region will be possible

extracting the benthic mixing impulse response function a constrained deconvolution technique abstract benthic mixing or bioturbation acts as a low pass filter on stratigraphic signals altering both the apparent rates and amplitudes of recorded events the mixing process is represented as a time invariant convolution and uses an impulse response function irf parameterized in terms of mixed layer thickness and mixing intensity diffusion coefficient such parameterization facilitates construction of the inverse deconvolution model which is used to examine the effects of incorrect irf characterization on deconvolution results results show that mixing intensity is as important a parameter as mixed layer thickness when unmixing a stratigraphic signal stable oxygen isotope records from two different species of planktonic foraminifers with changing relative abundances in the same core will show apparent offsets in the timing of events due to mixing the offset can be used with the appropriate unmixing equation to constrain mixed layer thickness and mixing intensity based on analysis of actual isotope signals the assumption is that any offsets in the records of the two species are totally a product of the mixing process the technique was applied to a high resolution glacial interglacial record termination ii from an equatorial pacific piston core multiple lateral subsamples were stacked to increase signal to noise ratio a multidimensional nonlinear optimization routine simplex was used to minimize an error function related to stratigraphic offsets between the two species a solution to this problem yielded a mixed layer 5 cm thick and a mixing intensity of 7 cm2 ka 1 this mixed layer thickness is at the low end of estimates based on 14c profiles in box cores from the same geographic area the mixing operator is probably conservative and does not take into account that sedimentation rates were higher during the last glacial period than during the holocene this may explain the inability of the algorithm to completely remove the stratigraphic offset between the two isotope records the unmixed record using the parameters 5 cm and 7 cm2 ka 1 shows a deglaciation overshoot which is distinctly smaller than the meltwater spike proposed earlier i e less than 0 1 versus a range of 0 3 1

a model for particle selective transport of tracers in sediments with conveyor belt deposit feeders conveyor belt deposit feeding organisms prevalent in both marine and freshwater systems have a profound effect on sediment properties and transport processes these organisms ingest sediments over a range of depths while depositing gut contents from tails protruding above the sediment surface this action results in particle selective transfer of buried materials to the sediment surface and imposes an accelerated rate of sediment and pore water burial within the feeding zone most previous efforts to combine sediment diagenesis with the effects of biogenic reworking characterize mixing as exclusively diffusive and ignore such major advective effects here a model is developed based on fundamental diagenetic equations for transport and reaction for the distribution of tracers in accumulating sediments subject to compaction and diffusive as well as advective redistribution by benthic organisms conveyor belt cb feeding is characterized as a first order process with a depth dependent rate constant which is either localized gaussian or distributed integrated gaussian biogenic diffusivity of bulk sediments is allowed these alternative depth dependences as well the model assumes simple linear adsorption of the tracer between solid and solution phases and uses a time dependent flux at x 0 which is a combination of that originating externally and the depth integrated contributions from feeding particle selectivity is introduced by applying mass conservation separately to transport of the tracer and bulk sediments properties of the model are illustrated for tracers in nondispersive systems strongly bound to sediment solids cb recycling gives rise to transient reflections on passage of a tracer pulse through the zone of bioturbation reflections readily disappear in the presence of various integrative processes the system time resolution is defined in terms of the downward propagation of dual tracer pulses and shown to be systematically degraded by intensified feeding and selective transport a simple expression is developed for estimating the magnitude of particle selective changes in steady state surface concentrations in terms of the particle selectivity factor and the efficiency of sediment reworking unrecognized particle selectivity can lead to false inferences about changes in the rate of delivery of tracers to sediments selective cb recycling can cause a tracer such as 210pb to be retained largely within the bioturbation zone so that relatively little activity reaches the region of sediment useful for geochronological interpretation increased selectivity accentuates the sensitivity of the profile to details of the reworking process the model applied to previous studies of cb deposit feeders in tracer labeled freshwater microcosms shows the need to include particle diffusion as well as advection in the treatment of cb transport

internal architecture of mixed tide and storm influenced deposits an example from the alcântara formation northern brazil abstract the uppermost portion of the itapecuru group is exposed in the eastern margin of the sao luis basin northern brazil where it consists of two units the alcantara formation cenomanian and the cujupe formation late cretaceous early tertiary rossetti d f truckenbrodt w 1997 revisao estratigrdfica para os depositos do albiano terciario inferior na bacia de sao luis ma norte do brasil bol mus paraense emilio goeldi ser cienc terra in press the alc ntara formation which contains the large scale structures discussed in this paper consists of deposits attributed to mid to upper shoreface foreshore tidal channel and lagoon washover environments attributed to a regressive barred shoreline several types of large scale cross bedding i e simple foreset compound mixed undulatory and intricately bounded were recognized in the shoreface facies association these structures are interpreted to record the interaction of storm and tidal processes the storm influence is suggested by a combination of factors mostly including a the genetic association with other storm generated sedimentary structures i e swaley cross stratification and undulating parallel lamination with internal truncations b the deposition on prominent surfaces formed by storm erosion which are defined by large scale either symmetrical or asymmetrical scours arranged in a regular repeating pattern c the sedimentary features formed under combined unidirectional and oscillatory flow processes e g compound mixed bedding with superimposed either swaley cross sets or complexly truncating cross sets with highly undulating boundaries large scale undulatory and intricately bounded cross beddings and d the lateral change in structural styles within short distances which records frequent modification from asymmetrical to symmetrical nearly symmetrical bedform profiles more likely to occur under storm generated combined flows the tidal signature is locally recognized by regularly spaced thick thin sandstone bundles defined by reactivation surfaces and or mud drapes which are attributed to tidal ebb flood cycles the analysis of paleocurrent distribution suggests that vigorous southwestward oriented storm flows interacted with local tidal currents on the shoreface to promote the landward transport of significant volumes of sand which resulted in the large scale cross stratification described in this paper in addition a secondary southeastward directed oblique to shore parallel combined flow would have periodically interacted with the main flow the origin of this oblique to shore parallel flow is attributed to either the refraction of the main storm waves as they approached the paleocoastline or the interference of a separate storm episode which competed with the major landward moving one this complex storm flow pattern can be related to past penecontemporaneous seismic activity i e tsunamis as suggested by the paleogeography of the study area during the cenomanian combined with the structural history of the sao luis basin and the sedimentary features recognized in the alcantara formation

sedimentology faunal content and pollen record of middle pleistocene palustrine and lagoonal sediments from the peri adriatic basin abruzzi eastern central italy abstract a 25 m thick outcrop section exposed at torre mucchia on the sea cliff north of ortona eastern central italy comprises a rare middle pleistocene succession of shallow water and paralic sediments along the western adriatic sea an integrated study of the section including facies and microfacies analyses and characterization of paleobiological associations mollusks fishes ostracods foraminifers and pollen enable a detailed reconstruction of the paleoenvironmental and paleoclimatic conditions during deposition the shallow water deposits include a transgressive deepening and fining upward shoreface to offshore transition facies succession overlain by a regressive shoreface foreshore sandstone body with an erosive base and a rooted and pedogenically altered horizon at the top that imply deposition during sea level fall this forced regressive unit is overlain by paralic strata forming a transgressive succession comprising palustrine carbonates and back barrier lagoonal mudstones the palustrine carbonates exhibit some of the typical features encountered in palustrine limestones deposited within seasonal freshwater wetlands marl prairies following the sea level rising trend the freshwater marshes were abruptly replaced by a barrier lagoon system that allowed deposition of the overlying mud rich unit within these deposits the faunal assemblages are consistent with a low energy brackish environment characterized by a relatively high degree of confinement the pollen record documents the development of open forest vegetation dominated by pinus and accompanied by a number of mesophilous and thermophilous tree taxa whose composition supports a tentative correlation with marine oxygen isotope stage 17 the new pollen record from torre mucchia improves our understanding of the vegetation development in the italian peninsula during the middle pleistocene and sheds new light on the role played by the most marked glacial periods in determining the history of tree taxa

storm and tide dominated shorelines in cretaceous moosebar lower gates interval outcrop equivalents of deep basin gas trap in western canada the moosebar and gates formations crop out in the deformed foothills belt south of fort st john british columbia they permit examination of the depositional environments of sandstones and conglomerates that are gas bearing in the equivalent wilrich falher interval of the deep basin of alberta and british columbia the moosebar gates interval consists of several upward coarsening and marine to nonmarine sequences moosebar bioturbated shales pass upward into turbidites and offshore storm deposits flow directions indicate a north dipping paleoslope a second coarsening upward sequence at the top of the moosebar and base of the gates terminates in a lenticular fluvial conglomerate up to 30 m thick which is overlain by coals carbonaceous mudstones and sandstones above the carbonaceous zone a major lateral facies change is observed fluvial conglomerates in the south grade into beach conglomerates northward the upper part of the beach conglomerate consists of exposed three dimensional storm berms at least 500 m long up to 1 5 m high with wavelengths of 12 to 24 m the berms trend east west seaward of the conglomerate beach are herringbone cross bedded tidal sandstones with a marine trace fauna graded sharp based conglomerates also are present probably washed out to sea by storms farther north at the same stratigraphic level is a series of partly overlapping conglomerate bars up to 5 m thick and 40 to 50 m across the tops of these bars are covered with storm formed symmetric conglomeratic dunes details of the orientation and geometry of these conglomerate bodies along with their internal structure and pebble fabrics suggest that four major environments fluvial beach offshore conglomerate bars and offshore graded storm conglomerates should be identifiable and predictable in the subsurface

poseidon s horses plate tectonics and earthquake storms in the late bronze age aegean and eastern mediterranean abstract in light of the accumulated evidence now published the oft denigrated suggestion that major earthquakes took place in the aegean and eastern mediterranean areas during the late 13th and early 12th centuries bc must be reconsidered a new study of earthquakes occurring in the aegean and eastern mediterranean region during the 20th century utilizing data recorded since the invention of seismic tracking devices shows that this area is criss crossed with major fault lines and that numerous temblors of magnitude 6 5 enough to destroy modern buildings let alone those of antiquity occur frequently it can be demonstrated that such major earthquakes often occur in groups known as sequences or storms in which one large quake is followed days months or even years later by others elsewhere on the now weakened fault line when a map of the areas in the aegean and eastern mediterranean region affected i e shaken by 20th centuryad earthquakes of magnitude 6 5 and greater and with an intensity of vii or greater is overlaid on robert drews map of sites destroyed in these same regions during the so called catastrophe near the end of the late bronze age it is readily apparent that virtually all of these lba sites lie within the affected high shaking areas while the evidence is not conclusive based on these new data we would suggest that an earthquake storm may have occurred in the late bronze age aegean and eastern mediterranean during the years 1225 1175bc this storm may have interacted with the other forces at work in these areas c 1200bc and merits consideration by archaeologists and prehistorians

the resolution of stratigraphic inconsistency in the luminescence ages of marine terrace sediments from korea several sets of marine terraces are exposed along the southeastern coast of the korean peninsula the formation ages of these terraces have attracted considerable attention because they provide essential information on local crustal stability over the last few years considerable effort has been put into the determination of these ages using optically stimulated luminescence osl dating of the marine sediments from which the terraces were built for several sites the results of dose recovery tests and other osl characteristics including the dependence of equivalent dose on heat treatment prior to stimulation have been described in detail elsewhere quat sci rev 22 2003 407 however it has been found that the samples from one site exhibit various undesirable osl characteristics which result in stratigraphically inconsistent osl ages in this paper we investigate these characteristics and use luminescence component separation to resolve this inconsistency the resolved osl ages obtained as such are then used for the discussion on the local crustal stability of the southeastern coast of korea during the late pleistocene

earthquakes and archaeology abstract this article examines the use of archaeological evidence for the assessment of historical earthquakes in the eastern mediterranean region and middle east long before the advent of modern seismology we ask the questions when and where have large earthquakes happened in the past how can this evidence contribute to our scientific understanding of earthquake activity is it possible on literary and archaeological grounds to distinguish between earthquake damage and damage from other causes it is found that archaeological evidence for an earthquake is not always clear or unambiguous and that there is a need for collaboration between archaeologists historians geologists engineering seismologists and workers in other disciplines to evaluate the traces of earthquakes in excavations both for understanding their effects at the site and for the information they can provide about the nature of the earthquake implicated

a model for 137cs and other tracers in lake sediments considering particle size and the inverse solution abstract a numerical model for the time dependent behavior of particle associated tracers in sediments has been developed the model is based on the advection diffusion equation for a tracer and includes a sediment density that increases with depth as a modified power function and a diffusion coefficient that follows a half gaussian function versus depth with maximal diffusivity at the sediment water interface the solution procedure is based on finite elements or finite differences the density function is developed from soil mechanics concepts and includes mixing effects through a young s modulus that is increased in the top layer according to a half gaussian function the new density function provides a better fit to 15 out of 17 sediment cores from lake michigan than a frequently used exponential expression the tracer model provides an excellent fit for the 137cs distributions in all of the 17 lake michigan cores that were investigated our fit to the 137cs profile of a southern lake michigan core that has been examined by others is significantly better than previous fits particularly near the top of the core from two different forms of the governing equation for a tracer and the resultant fits to experimental data it appears that 137cs is associated with colloidal and 210pb with settling particles a previously developed time domain method to extract the historical input record of a tracer from its sedimentary profile influenced by mixing has been further improved by including m depth and n time intervals where m n and by fitting the influx to a polynomial the improved method is demonstrated for the cd input to a northern lake michigan core nlm84b although the time resolution obtained 5 yr is better than the previous resolution 15 yr it is clear that the method needs to undergo further development in order to decrease the error of the reconstructed influx and particularly to avoid negative fluxes

is there evidence for geostrophic currents preserved in the sedimentary record of inner to middle shelf deposits abstract unidirectional oscillatory and combined flow paleocurrent data from many ancient wave dominated coastlines indicate that sediment transport was directed offshore at angles of 70 to 90 from the inferred local paleoshoreline solemarks and parting lineations from turbidite like storm beds and solemarks from hummocky beds indicate that flows transporting sediment offshore were orthogonal to the local shoreline the shore normal orientations of solemarks parting lineation and asymmetric ripples on hummocky cross stratification and their orthogonal relationship with respect to wave ripple crest orientation indicate that the dominant direction of wave approach at the sediment water interface was also orthogonal to the shoreline the formation of hummocky cross stratification by an al ng shore flow component superimposed on oscillatory wave motion is not supported by paleocurrent data rather much of the evidence from the ancient record suggests that hummocky cross stratification forms under high energy oscillatory flow with a weak shore normal combined flow component the orientation of wave ripple crests from the lower shoreface to offshore transitional zone of wave dominated coasts can be used to approximate the local paleoshoreline trend the paleocurrent data from the ancient examples suggest a strong predominance of offshore directed sediment transport as opposed to the nearly shore parallel orientation of currents observed in modern geostrophic flows

slip rates on the helike fault gulf of corinth greece new evidence from geoarchaeology palaeoseismological and archaeological analysis of a trench enabled us to estimate the holocene slip rates on the east helike fault flanking the south western gulf of corinth we recognized two major fault strands within the trench the north fault controls a succession of three colluvial wedges and the deposition of a 2 7 m thick sedimentary sequence the south fault controls the deposition of a 2 9 m thick brownishred colluvium based on colluvial stratigraphy radiocarbon dating of the sediments suggests that the slip rate was c 0 3 mm yr 1 from 10 250 to c 1400 bp when it increased dramatically to c 2 0 mm yr 1 after a strong earthquake event near 1400 bp the faster slip rate evidently increased the sedimentation rate

determination of mixing parameters from tracer distributions in deep sea sediment cores abstract computer optimization and approximate analytical procedures are developed for the determination of the depth of bioturbation mixing d and the mixing coefficient d for instantaneous tracer inputs the methods have been applied to observations of microtektites volcanic ash and pumice in sixteen deep sea sediment cores the values for d are well determined generally with confidence intervals of a few centimeters or less and with an average value of d 11 cm for the sixteen cores the values for d are determined to first figure accuracy at best with values of around 10 cm 2 ka 1 or greater

late holocene evolution of the east eliki fault gulf of corinth central greece abstract trench stratigraphy and morphotectonic analysis was used to examine the recent evolution of the helike eliki plain and eliki fault the entire alluvial plain of the kerynites and vouraikos rivers which cross the eliki fault has subsided at rate of 1 4 mm yr resulting in the burial of the late hellenistic roman occupation horizons under 3 m of fluvial and colluvial sediments along the eastern segment of the eliki fault five trenches have been excavated and their 5000 yr old fluvial and colluvial deposits have been studied in association with the fault strand imprinted on them the kerynites river crosses at high angle the eliki fault and appears to be sensitive in tectonic movements related with the eliki fault sedimentation in the alluvial plain and the fluvial geomorphology of the kerynites river is important for understanding the fault evolution and the burial of the ancient 4th century bc helike city the kerynites river course highlights breaching deformation is the more likely to connect east and west eliki fault segments and that postseismic deformation is a significant mechanism for stress accommodation for part of the west end of the gulf of corinth

quaternary evolution of the corinth rift and its implications for the late cenozoic evolution of the aegean summary we present geological and morphological observations at different scales to constrain rates of faulting and the distribution of deformation in the seismically active aegean region we focus first on the 130 km long corinth rift an asymmetric graben where a flight of terraces of marine origin are uplifted we show that the edges of the terraces lie in the footwall of the normal fault bounding the corinth rift and correspond to sea level highstands of laic pleistocene age using a detailed analysis of aerial and spot imagery supported by field observations we have mapped 10 terrace platforms and strandlines ranging in elevation from 10 to 400 m over distances of 2 to 20 km from the fault the elevation of the terraces inner edges was estimated at 172 sites with an error of 5m this data set contains a precise description of the uplift and flexure of 10 different palaeohorizontal lines with respect to the present sea level to date the deformation we correlate the corinth terraces with late pleistocene oxygen isotope stages of high sea level stands and with global sea level fluctuations using a thick elastic plate model consistent with our current understanding of the earthquake cycle and a boundary element technique we reproduce the geometry of the shorelines to constrain both mechanical parameters and the slip on the fault we show that the seismogenic layer behaves over the long term as if its elastic modulus were reduced by a factor of about 1000 all the terraces are fitted for fault slip increasing in proportion to terrace age and the component of regional uplift is found to be less than 0 3 mm yr 1 the best fits give a slip rate of 11 3 mm yr 1 on the main rift bounding fault over the last 350 kyr other geological and morphologic information allows us to estimate the total age of the main fault 1 ma and to examine the mechanical evolution of the corinth rift the minimum observed sediment thickness in the gulf places an extreme check on the results of the modelling and a lower bound on slip rate of 6 7 mm yr 1 40 per cent less than estimated with modelling even this slip rate is nearly 10 times higher than for comparable features in most of the aegean and elsewhere in the world at a larger scale the spacing and asymmetry of the rift systems in the aegean suggest strain localization in the upper mantle with slow extension starting 15 myr ago or earlier the more recent 1 myr rapid phase of rifting in corinth partly reactivated this earlier phase of extension the younger faulting in corinth appears to result from its present location in the inhomogeneous stress field process zone of the south westward propagating tip of the southern branch of the north anatolian fault we extend these relations to propose a mechanical model for the late cenozoic evolution of the aegean as the arabia europe collision progressed in eastern turkey it caused anatolia to move to the west and the north anatolian fault to propagate into the aegean where the early slow extension started to be modified about 5 ma ago the process of propagation dramatically increased the activity of some but not all of the earlier rifts the model we present is compatible with tectonic observations as well as with the seismicity the palaeomagnetic rotations and the displacement field now observed with gps and slr

lichen dating of earthquake generated regional rockfall events southern alps new zealand synchronous regional rockfall events triggered by large earthquakes in the southern alps of new zealand were used to evaluate and improve the lichenometry method for surface exposure dating digital calipers were used to measure the maximum diameter of the largest lichen on many rockfall blocks using a fixed area largest lichen fall sampling strategy regional significance of fall peaks can be tested by confirming the occurrence of a coeval peak at multiple sites and by showing an increase in peak size toward the earthquake epicenter significance of fall peaks at a local site can be described in terms of peak size relative to a uniform density of fall sizes measurements of 34 000 fall sizes on fully exposed rockfall blocks and outcrop joint faces at 90 sites allow precise dating of geomorphic events of the past 300 to 500 yr uncertainties at the 95 confidence interval can be reduced to a level better than 10 yr for ages within the calibrated time range represented by the lichen growth equation recognition of prehistorical regional rockfall events in 1833 1836 and 1840 demonstrates the excellent resolution of this dating method precise dates result from exceptionally low measurement errors of lichen sizes relative to their growth rate tightly clustered fall sizes for earthquake induced rockfall events and substrate exposure times for calibration sites that are known to the year or day fall peaks for synchronous rockfall events are the same for 20 sites with diverse climate altitude and substrate lithology a regionally consistent lichen growth rate allows use of a single growth rate equation for most species of rhizocarpon subgenus rhizocarpon on the south island of new zealand a nonlinear growth equation suggests that the first colonization on average occurs in the 5th yr after formation of new rock surfaces 0 5 m 2 unit areas and is followed by rapid exponentially declining growth for about 20 yr greatgrowth phase that is largely completed by the 24th yr then linear growth persists at about 15 mm per century uniform growth phase

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

interpretation procedures for the determination of sediment parameters from time dependent flux inputs abstract a formulation for the effects of a time dependent input flux to a sedimentation system consisting of a diffusive layer underlain by a non diffusive medium has been developed the intent is to provide interpretation procedures for the determination of sedimentation rate diffusion coefficient and mixed layer thickness from observed tracer concentrations they have been applied for illustrative purposes to published137cs and239 240pu measurements

grain fabric in hummocky cross stratified storm beds genetic implications abstract a detailed analysis of grain fabric in samples from hummocky cross stratified hcs storm beds suggests that these shallow marine sandstones were deposited from waning combined oscillatory unidirectional flows particle a axis orientations in the deposits in plan view parallel to visible lamination vary widely but have a mean orientation approximately normal to unidirectional paleoflow indicators sole marks and subparallel to regional shoreline this alignment of a axes is attributed to deposition under combined flows with a multidirectional oscillatory component produced by wind induced surface gravity waves with a modal crest orientation approximately parallel to the shoreline imbrication of particles varies in both the horizontally laminated and hcs intervals of the hcs stor beds due to waxing and waning of boundary shear stress caused by the oscillatory component of the flow in the basal horizontally laminated interval of an hcs storm bed grain imbrication angles vary about a mean of approximately 13 from the horizontal dipping into the paleoflow inferred from sole marks this preferred imbrication direction is attributed to boundary shear stress influenced by the unidirectional component of the combined flow however quasi cyclic variation in imbrication angle over a broad range and periodic reversal of imbrication direction suggest that the oscillatory component was also significant during deposition of the horizontally laminated interval in hcs intervals imbrication angles vary about a mean that is parallel to visible laminae suggesting th t oscillatory flow had become predominant the sequence of structures and changing patterns of fabric through these hcs storm beds is consistent with deposition under waning combined flows erosional scour forming the sharp base and unidirectional sole marks occurred in response to combined flows with an effective unidirectional component the unidirectional component continued to influence the direction of boundary shear stress during deposition of the horizontally laminated sands but waned and became negligible relative to a strong oscillatory component during formation of hcs

modeling radiotracers in sediments comparison with observations in lakes huron and michigan a comprehensive model for the activity of radionuclides in sediments is presented the model is based on the advection diffusion equations for sediment solids and a radioactive tracer mixing caused by deposit feeders is taken into account by a half gaussian hg integrated gaussian ig or exponential ex diffusion coefficient with a maximum value d0 at the sediment water interface and an effective mixing depth m where m hg zm ig or a ex compaction is described by an exponential bulk sediment density the differential equations are solved by finite differences in particular the crank nicolson method for the time dependent case cs 137 estimation of the mixing parameters d0 and m is carried out efficiently by minimizing chi square for measured and calculated steady state pb 210 activities the derived mixing depths of zm 4 6 0 1 cm station 14 and a 0 8 0 1 cm station 18 for the cores from lake huron are in good agreement with the organism distributions the corresponding d0 values are 12 2 and 1 5 0 5 cm2 yr respectively where the latter number is lower than a previous lower limit estimate 3 3 cm2 yr based on 1974 data these diffusion coefficients are in excellent agreement with those inferred from the densities of pontoporeia and tubificid oligochaetes 9 3 and 1 6 cm2 yr respectively compared with southern lake michigan there appears to be less sediment focusing in northern lake michigan where the ratios of measured to atmospheric cs 137 inventories have an average value of 0 89 and range from 0 32 to 1 41 for six cores from the deep basin when these ratios are used to correct the pb 210 fluxes we obtain an atmospheric pb 210 flux of 0 99 0 06 dpm cm2 yr because of its more realistic activity profiles we consider the present model to be generally better than previous models

archaeoseismological studies on historical heritage sites in the gyeongju area se korea abstract recently a fallen buddha statue of the late 8th century was discovered in mt nam gyeongju se korea the gyeongju area is located in intersection of two major young structural features in korea the yangsan and ulsan faults according to historical records such as the ancient texts of samguksagi chaljubongi and mukseojipyeon the studied area was significantly affected by several large earthquakes of mm intensity vii and estimated magnitude up to m l 6 7 such as the destructive events occurred in 768 ad 779 ad and 1036 ad especially the last two earthquakes are historically well documented as triggering severe damages in other historical buildings hwangryongsa pagoda and bulguksa temple around the area this paper examines the potential connection between the fallen buddha statue and any of the large historical earthquakes documented in the area restoration study of the original position of the fallen buddha statue based on fracture analysis indicates that the fallen buddha statue rotated 20 clockwise and slid a few meters from its original position during a large rockfall event preliminary osl dating was carried out from weathered soil below a large granite block adjacent to the fallen statue the age of 0 76 0 12 ka indicates a bracketed time period between the years 1130 and 1370 ad for the statue fall however no earthquake is reported for this time period in the area although the available data does not exactly indicate any specific earthquake based on the historic records artistic styles differential weathering of the statue osl dating and nearby historically documented archaeoseismic damage the 1036 ad earthquake m l 6 4 is proposed as the more likely event responsible for the studied damage furthermore other earthquake damage to historic heritage sites was also reported in historical records around the study area therefore a future seismic hazard study should be carried out to preserve the important national heritage sites in this area the combination of paleoseismological and archaeoseismological studies is essential to estimate potential earthquake hazard in this area

modeling reactive transport in sediments subject to bioturbation and compaction current bioturbation models are marked by confusion in their treatment of porosity different equations appear to be needed for different biodiffusion mechanisms i e interphase mixing where biological activity causes bulk mixing of sediment affecting both tracer and porosity profiles versus intraphase mixing where the solid components are intermixed but the porosity is left unchanged another issue is whether the model depends upon the particle type with which tracers are associated e g 137 cs on small clay particles versus 210 pb on larger grains this uncertainty has lead to conflicting conservation equations for radiotracers and in particular to the question whether the porosity should be placed inside or outside of the differential term that governs the biodiffusive flux we have reexamined this situation in the context of multiphase multicomponent continuum theory most importantly we prove that under the assumption of steady state porosity there exists only one correct form of the steady state conservation equation for a radiotracer regardless of biodiffusion mechanism and particle type i e

ripple cross stratification in swaley cross stratified sandstones of the chungo member mount yamnuska alberta swaley cross stratified sandstones are exposed in the late cretaceous chungo member of the wapiabi formation at mount yamnuska alberta at this site many of the individual flaggy weathering thin beds of sandstones that make up the swaley cross stratified structure are internally ripple cross stratified the association of swaley and ripple cross stratification has not previously been described and is interpreted to indicate compound cross stratification generated under combined flow condi tions furthermore this association brings into question the possible genetic relationship between swaley cross stratification and hummocky cross stratification a sedimentary structure generated under purely oscillatory conditions

archaeoseismic record at the ancient roman city of baelo claudia cadiz south spain this study represents the first paleoseismic approach in spain in which archaeological remains are considered the ancient roman city of baelo claudia 1st 4th centuries ad located at the axial zone of the gibraltar strait cadiz south spain contains abundant disrupted architectural relics and ground collapses i e landsliding liquefacion probably related to historic earthquake damage of intensity ix x msk the archaeological stratigraphy of the city evidence two major episodes of abrupt city destruction bracketed in ad 40 60 and ad 350 395 separated by an intervening horizon of demolition for city rebuilding otherwise characteristic for many earthquake damaged archaeological sites in the mediterranean the second episode led the eventual city abandonment and it is evidenced by good examples of column collapse distortion failure and breakdown of house and city walls and pavement warping and disruptions documented during different archaeological excavations which can be catalogued as secondary coseismic effects main damaged relicts observable today are the set of pop up like arrays and warping developed in the ancient roman pavement their analysis indicate an anomalous westwards ground displacement oblique to the main gentle southward slope of the topography as also evidence failures collapses and breakdown of walls and columns suggesting that stress acted in a broad sw ne wsw ene orientation consistent whit the expectable motion along the largest ne sw strike slip faults of the zone which in turn can be catalogued as seismic sources of moderate events ca 5 mb major disruptions and city abandonment were hesitantly related to relatively far strong earthquakes occurred during the late 4th century ad in the mediterranean or western coast of iberia by menanteau et al menanteau l vanney j r zazo c 1983 belo ii belo et son environment detroit de gibraltar etude physique d un site antique pub casa de velazquez serie archeologie 4 ed broccard paris however this study indicates that the occurrence of close moderate earthquakes jointly with the unstable character of the ground at the zone site effect is a more reliable hypothesis to explain the observed deformations

faulting and effects of earthquakes on minoan archaeological sites in crete greece abstract examination of damages affecting the buildings of the archaeological sites of phaistos and agia triada southern crete suggests that these minoan settlements were probably destroyed by two major seismic events characterized by mks intensities of ix x and occurred at the end of the protopalatial 1700 bc and the neopalatial 1450 bc periods geological and morphological studies carried out in the neighbouring areas show the occurrence of e w trending quaternary normal fault segments spili and agia galini faults that control the present topography and morphology and exhibit steep young scarps mostly holocene in age these fault segments are related to a nw se extension direction which is consistent with that indicated by the available focal mechanisms of the earthquakes occurring in this area in the last 50 years combining structural and seismic data we can infer that the spili and agia galini fault segments could represent good candidates to be considered active faults generating large earthquakes m 6 5 that were responsible for the damages of phaistos and agia triada this hypothesis suggests that the minoan palatial centres were destroyed by several large earthquakes related to ruptures along distinct fault segments rather than by a single catastrophic event that caused the abrupt destruction of the minoan civilisation in the eastern mediterranean

atmospheric fluxes of lead zinc and cadmium from frequency domain deconvolution of sedimentary records a frequency domain deconvolution method to extract past input fluxes of particle associated pollutants from their sedimentary records is developed the method is based on the assumption of a mixing layer below which no further mixing takes place from the latter historical layer a filtered time record is obtained also from known steady state sedimentation parameters a response to a unit impulse input is calculated by forward finite difference programs the unknown input flux is then generated by taking fourier transforms of the two time series forming the ratio of the transforms and applying the inverse frequency transform the method has been tested for internal consistency and applied to pb zn and cd in several sediment cores from lake michigan the results are consistent with those obtained previously with a time domain method however at the present stage of development the time resolution in the frequency method 1 year is considerably better than in a general time domain method 15 years the effects of deconvolution are to sharpen peaks to generate peaks where none were present in the unprocessed record and to shift the onset time of pollution towards more recent times in most cases there is a remarkable agreement between reconstructed input records and alternative source functions for example maxima around 1969 for pb and cd in deconvolved input records are confirmed by the atmospheric loading data for the great lakes region pb and u s consumption figures cd

recognition of earthquake related damage in archaeological sites examples from the dead sea fault zone abstract archaeological structures that exhibit seismogenic damage expand our knowledge of temporal and spatial distribution of earthquakes afford independent examination of historical accounts provide information on local earthquake intensities and enable the delineation of macroseismic zones they also illustrate what might happen in future earthquakes in order to recover this information we should be able to distinguish earthquake damage from anthropogenic damage and from other natural processes of wear and tear the present paper reviews several types of damage that can be attributed with high certainty to earthquakes and discusses associated caveats in the rare cases where faults intersect with archaeological sites offset structures enable precise determination of sense and size of slip and constrain its time among the characteristic off fault damage types i consider horizontal shifting of large building blocks downward sliding of one or several blocks from masonry arches collapse of heavy stably built walls chipping of corners of building blocks and aligned falling of walls and columns other damage features are less conclusive and require additional evidence e g fractures that cut across several structures leaning walls and columns warps and bulges in walls circumstantial evidence for catastrophic earthquake related destruction includes contemporaneous damage in many sites in the same area absence of weapons or other anthropogenic damage stratigraphic data on collapse of walls and ceilings onto floors and other living horizons and burial of valuable artifacts as well as associated geological palaeoseismic phenomena such as liquefaction land and rock slides and fault ruptures additional support may be found in reliable historical accounts special care must be taken in order to avoid circular reasoning by maintaining the independence of data acquisition methods

eolian aqueous interactions in the development of a proterozoic sand sheet shikaoda formation hosangabad india abstract a 40 m thick eolian sand sheet deposit characterizes the upper part of the proterozoic shikaoda formation near hosangabad it sharply overlies shoreface deposits and comprises wind ripple strata 50 adhesion strata 17 and subaqueous strata 33 each stratification type defines stratal packages tens of centimeters thick and few meters wide that are superposed upon one another in a nearly random fashion the eolian facies is inferred to have been deposited in a low gradient sandy supratidal setting the subaqueous deposits of the sand sheet also reflect a tide affected westward opening coastal setting with an approximately north south shoreline abundance of aqueous and adhesion strata coupled with the absence of granule rich coarse grained layers corrugated erosion surfaces and evaporites are the typical features of the shikaoda eolian sand sheet these features indicate that in spite of abundant sand supply from the coastal sources and a net aggradational setting repeated flooding and high surface moisture were the principal factors that inhibited dune building processes and favored the growth of a flat bedded eolian sand sheet in the shikaoda sandstone numerous subhorizontal nearly flat bounding surfaces split the sand sheet succession into tabular sediment bodies 50 100 cm thick each of the bounding surfaces can be traced for a few tens of meters and can be correlated to an event of aqueous flooding vertical stacking of tabular sandstone bodies implies that long term sediment aggradation rate in the low lying supratidal region kept pace with that of basin subsidence the sedimentological features of the shikaoda sand sheet facies when compared with known modern and ancient sand sheet deposits suggest that the shikaoda sand sheet developed independent of an erg in a comparatively wet climatic setting the sub humid coastal eolian sedimentary system of padre island texas is probably the closest modern analogue of the shikaoda sand sheet facies

nonlinear parameter estimation for sediment cores abstract nonlinear parameter estimation techniques are applied to three distinctly different sediment cores for which concentrations of tracers with steady and time dependent flux inputs are available the mathematical model employed consists of a diffusive upper layer of finite depth underlain by a semi infinite nondiffusive medium confidence regions and intervals are reported for sedimentation rate diffusion coefficient and mixed layer depth based on ordinary least squares criteria for each tracer conflicting estimates are resolved using a weighted least squares procedure which combines observations of the individual tracers and exploits their strengths and weaknesses

geometry and kinematics of active faults and their seismotectonic significance in the western corinth patras rift greece abstract the western part of the corinth patras rift is formed in an area which is being uplifted rifted domains have subsided relative to the adjacent areas in nw peloponnesus and sterea hellas but subsidence rates rarely exceed uplift rates extension is mainly accomplished by wnw trending active faults with lengths up to 25 km most of these faults show an along strike segmentation and often terminate against transfer faults displacement analysis along 170 mesoscopic faults and 36 mappable faults has been carried out to assess slip rates and to estimate the magnitudes and recurrence time intervals of earthquakes occurring along them earthquake magnitude ranges between 5 and 6 7 only eight faults appear to be capable of producing earthquake magnitudes larger than 6 recurrence times of these large earthquakes vary between 80 and 1690 years upper crustal deformation in the western corinth graben can be described by six large asymmetric grabens which are inferred to bottom out to a n dipping curved ramp the asymmetric shape of most wnw trending rifts in the hellenic peninsula including the corinth patras rift promotes the simple shear model of extension against the pure shear model in the upper crustal layer

interpretation of the rupture history of a low slip rate active fault by analysis of progressive displacement accumulation an example from the quaternary eupcheon fault se korea abstract the eupcheon fault one of more than 20 identified quaternary faults recently reported in the area around the yangsan and ulsan faults se korean peninsula was discovered during the construction of a primary school in an area close to a nuclear power plant we analysed a trench excavated across the eupcheon fault with the aim of understanding its movement history and kinematics the eupcheon fault is a reverse fault strike dip n20 e 40 se that records 6 7 m of displacement 3 4 m vertical separation the fault consists of a series of branch faults associated fault related folds and rotated pebbles a previous study reported that the fault originally recorded normal slip but was reactivated during the quaternary as a reverse fault we identified four or five quaternary faulting events upon the fault based on an interpretation of the trench logs including an analysis of colluvial wedges and measurements of displacement distance d x relationships along the fault we used a quantitative analysis of d x relationships commonly used for consolidated sedimentary rocks to interpret the deformation history of the fault from this we estimated the amount of slip in the range of 0 7 1 8 m for each of the five identified faulting events and the earthquake magnitude in the range of m w 5 4 7 4 we propose two ideal d x profiles for syndepositional and post depositional faulting and a tectonic evolution model for the area around this fault this approach may be applicable to analyses of earthquake hazards and studies of fault evolution elsewhere

a model for radionuclides in sediments influenced by mixing and compaction a model for the activity of radionuclides in sediments has been set up based on the one dimensional advection diffusion equation the model considers sedimentation mixing and compaction observed distributions of deposit feeding organisms and the nature of physical disturbances indicate that a gaussian diffusion coefficient may be appropriate two layer models with constant and gaussian mixing respectively in the upper layer are compared with measured pb 210 profiles for two cores from green bay lake michigan and it is found that the maximal diffusion coefficient d0 in the gaussian model is considerably greater than the constant d value e g d0 4 versus d 0 2 cm2 year if compaction effects are neglected the solution for the gaussian model is based on an approximate power series method compaction can be taken into account by using an exponential sedimentation rate or bulk sediment density by comparing with measured data for a lake ontario core it is seen that compaction alone can give an appreciable flattening of the activity curves near the top layers

evidence for 830 years of seismic quiescence from palaeoseismology archaeoseismology and historical seismicity along the dead sea fault in syria an edited version of this paper was published in earth and planetary science letters by elsevier science elsevier science retains the copyright to this paper copyright 2003 see also http dx doi org 10 1016 s0012 821x 03 00144 4 http atlas geo cornell edu deadsea publications meghraoui2003 epsl htm

optical dating of sediments a new method for dating sediments is proposed which determines the time since the sediment was last exposed to sunlight an argon ion laser is used to excite electrons from thermally stable light sensitive traps and the subsequent luminescence used as a measure of the past radiation dose two sample sequences spanning the periods 0 700 kyr and 0 6 kyr show steadily increasing luminescence with age an age of 62 8 kyr is obtained for a silt radiocarbon dated at 58 8 0 3 kyr problems were found with two much younger samples