stratigraphy structure absolute age and paleontology of the upper pleistocene deposits at sankaty head nantucket island massachusetts the sankaty head cliff of nantucket island massachusetts exposes drift of at least two glaciations and interglacial marine deposits radiocarbon amino acid racemization and uranium thorium analyses were used to determine the absolute ages of the beds the results indicate that 1 the sankaty sand correlates with oxygen isotope stage 5 sangamonian 2 the underlying drift is older than stage 5 illinoian or older and 3 the overlying drift is wisconsinan in age ostracodes and molluscs within the sankaty sand indicate that the marine climate during deposition of the lower part was somewhat warmer than the present climate off sankaty head and that the marine climate during the deposition of the upper part was as cold as or somewhat colder than the present climate the paleoenvironmental data support a stage 5 sangamonian age for the marine deposits

history of stage 5 sea level in bermuda review with new evidence of a brief rise to present sea level during substage 5a abstract oxygen isotope substage 5e is represented by the devonshire formation in bermuda the occurrence of these coastal marine deposits to about 5 m indicates pleistocene sea level data in bermuda do not need tectonic corrections a few published u series coral dates suggest that a conglomerate spencer s point formation may have formed during substage 5c geologic mapping however indicates that the eolianite beneath the conglomerate is pre rather than post devonshire formation in age as was previously thought and the aminostratigraphy of marine sheels also confirms the correlation of the spencer s point and devonshire formations substages 5c and 5a are represented by the southampton formation large eolianites comprise the bulk of this formation they are onlapped by a few small younger marine 1 m and eolian deposits aminostratigraphy confirms that these late southampton age deposits are significantly younger than the devonshire formation and u series dates indicate a substage 5a age the setting of some of these deposits along a protected shoreline precludes discounting their position as anomalous due to large storms this evidence that sea level in bermuda was at about present datum late in substage 5a agrees with interpretations of neotyrrhenian deposits of mediterranean shorelines but not with inferences from the deep sea oxygen isotope record or with data from uplifted coral reefs

the mid cretaceous earth paleogeography ocean circulation and temperature atmospheric circulation a reconstruction of the global paleogeography of the mid cretaceous 100 m y ago including adjustment of continental outlines to account for microplate movements cmstal shortening and accretion in mid cretaceous and later orogenic regions is described and a map presented on the modified continents coastlines and significant mountain ranges are added this paleogeography is used as a framework for a reconstruction of ocean surface circulation and temperature distribution then the main features of the atmospheric circulation are deduced using the paleogeography and ocean temperatures as boundary conditions relative to the present these features are a much weaker westerly wind belt and greater seasonality of wind patterns leading to more extreme surface climates over the continents slightly equatorward positions of the subtropical anticyclones and monsoonal regimes over the continental margins bordering tethys and the central atlantic a comparison of the results with climatic evidence from t

empirical ground motion prediction equations for northwestern turkey using the aftershocks of the 1999 kocaeli earthquake 1 we present ground motion models for northwestern turkey using the aftershocks of the mw 7 4 1999 kocaeli earthquake we consider 4047 velocity and acceleration records for each component of motion from 528 earthquakes recorded by stations belonging to regional networks the ground motion models obtained provide peak ground velocity peak ground acceleration and spectral accelerations for 8 different frequencies between 1 and 10 hz the analysis of the error distribution shows that the record to record component of variance is the largest contribution to the standard deviation of the calibrated ground motion models furthermore a clear dependence of inter event error on stress drop is observed the empirical ground motion prediction equations derived for both the larger horizontal and vertical components are valid in the local magnitude range from 0 5 to 5 9 and for hypocentral distances up to 190 km

empirical ground motion attenuation relations for the eastern alps in the magnitude range 2 5 6 3 in this paper we use a large data set of seismometric and accelerometric recordings 3168 vertical and 1402 for each of the horizontal components collected by various networks in the eastern alps to estimate empirical ground motion attenuation relations valid in the magnitude range 2 5 6 3 for distances of up to 130 km relations are developed for horizontal and vertical peak ground acceleration and velocity arias intensity response spectral acceleration and fourier amplitude for 46 periods between 0 1 and 2 sec we adopt a simple magnitude dependent attenuation model predicting closer attenuation curves and decreasing distance attenuation for increasing magnitude we use truncated regression analysis to deal with the problem of non triggering stations with respect to other approaches our solution does not require any discarding of data or the knowledge of which stations did not trigger our relations agree with others suitable for the study region for magnitudes greater than 5 8 while they have a faster attenuation for lower magnitudes in an attempt to reduce the standard deviation we have introduced soil classification into the relation as well as a characterization of sites by means of h v ratios these ratios were estimated either by earthquakes receiver function or by the background seismic noise nakamura s ratios similar to findings in other studies the improvement obtained with soil classification is negligible while h v ratios reduce the standard deviation by up to 22 finally we have investigated the implications of these new relations for seismic hazard assessment considering two sites of interest located in northeastern italy udine and gemona in both cases the difference in the hazard estimates for return periods shorter than 100 years is notable with respect to all other available relations

coexisting goethite and gibbsite from a high paleolatitude 55 n late paleocene laterite concentration and 13c 12c ratios of occluded co2 and associated organic matter abstract a late paleocene 60 ma bp lateritic soil from northern ireland the antrim paleosol herein referred to as nire contains coexisting goethite gibbsite phyllosilicate and hematite the fe iii oxides exhibit pisolitic and liesegang type morphologies that are mutually exclusive in hand specimens x ray diffraction xrd measurements of al substituted for fe in goethite indicate two populations 1 low al liesegang type goethites 0 mol al and 2 high al pisolitic goethites 9 to 24 mol al selective dissolution and incremental vacuum dehydration decarbonation were used to determine the concentration and 13c values of co2 occluded in the respective structures of the goethites and gibbsites in this complex mixture of nire lateritic minerals the fe co3 oh component in the high al goethites appears to retain a proxy carbon isotopic record of vadose zone co2 in the ancient soil the 13c values of co2 occluded in coexisting goethites and gibbsites indicate that these minerals did not form in equilibrium with the same environmental co2 the measured mole fractions x of fe co3 oh in the high al goethites range from 0 0059 0 0005 to 0 0077 0 0006 and correspond to soil co2 concentrations of 28 000 to 37 000 ppmv the average values of x and 13c for the four high al goethites are 0 0067 0 0007 and 20 1 0 5 respectively the 13c value of the organic matter undergoing oxidation in this midlatitude 55 n late paleocene soil appears to have been 28 2 taken together these data indicate an atmospheric co2 concentration of 2400 ppmv 1200 ppmv at 60 ma bp the inferred high concentration of atmospheric co2 would have been coincident with the warm global climate of the late paleocene and is consistent with the idea that co2 plays an important role in climate variation

the utica shale and gas play in southern quebec geological and hydrogeological syntheses and methodological approaches to groundwater risk evaluation abstract the risk of groundwater contamination from shale gas exploration and development is a major societal concern especially in populated areas where groundwater is an essential source of drinking water and for agricultural or industrial use since groundwater decontamination is difficult or nearly impossible it is essential to evaluate exploration and production conditions that would prevent or at least minimize risks of groundwater contamination the current consensus in recent literature is that these risks are primarily related to engineering issues including casing integrity and surface activities such as truck traffic equipment and fluid haulage waste management mainly drill cuttings and water storage and treatment when hydraulic fracturing is utilized concerns have also been raised with respect to groundwater contamination that could result from potential fracture or fault interconnections between the shale unit and surficial aquifers which would allow fracturing fluids and methane to reach the surface away from the wellbore despite the fact that groundwater resources are relatively well characterized in some regions there is currently no recognized method to evaluate the vulnerability or risks to aquifers resulting from hydrocarbon industry operations carried out at great depths this paper focuses on the utica shale of the st lawrence platform quebec where an environmental study aiming to evaluate potential risks for aquifers related to shale gas development has been initiated to provide the context of these research efforts this paper describes the regional tectono stratigraphic evolution and current stress regime of the cambrian ordovician st lawrence platform as well as the utica shale internal stratigraphy mineralogy and thermal maturation then the hydrogeological context of the st lawrence platform is discussed finally the methodology for this environmental study based on geological geophysical geomechanical hydrogeological and geochemical data is presented

the influence of magnitude range on empirical ground motion prediction a key issue in the assessment of seismic hazard in regions of low to moderate seismicity is the extent to which accelerograms obtained from small magnitude earthquakes can be used as the basis for predicting ground motions due to the larger magnitude events considered in seismic hazard analysis in essence the question is whether empirical ground motion prediction equations can be applied outside their strict range of applicability as defined by the magnitude and distance ranges covered by the datasets from which they are derived this question is explored by deriving new spectral prediction equations using an extended strong motion da taset from europe and the middle east covering the magnitude range mw 3 0 7 6 and comparing the predictions with previous equations derived using data from only mw 5 0 and above events the comparisons show that despite their complex func tional form including quadratic magnitude dependence and magnitude dependent attenuation the equations derived from larger magnitude events should not be extra polated to predict ground motions from earthquakes of small magnitude moreover the results suggest not only that ground motion prediction equations cannot be used outside the ranges of their underlying datasets but also that their applicability at the limits of these ranges may be questionable although only tested for smaller magni tudes the results could be interpreted to suggest that predictive equations also cannot be reliably extrapolated to higher magnitudes than those represented in the dataset from which they are derived a finding that has important implications for seismic hazard analysis the conclusion of the study is that empirical derivation of ground motion pre diction equations should be based on datasets extending at least one unit below the lower limit of magnitude considered in seismic hazard calculations the inclusion of small magnitude recordings results in a significant increase in the aleatory varia bility of the equations although it is yet to be established whether this is due to greater uncertainty in the associated metadata or whether ground motion variability is gen uinely dependent on earthquake magnitude

a model for vertical to horizontal response spectral ratios for europe and the middle east in the framework of probabilistic seismic hazard analysis the preferred approach for obtaining the response spectrum of the vertical component of motion is to scale the horizontal spectrum by vertical to horizontal v h spectral ratios in order to apply these ratios to scenario or conditional mean spectra the v h ratios need to be defined as a function of variables such as magnitude distance and site classification a new model for the prediction of v h ratios for peak ground acceleration and spectral accelerations from 0 02 to 3 0 s is developed from the database of strong motion accelerograms from europe and the middle east a simple functional form expres sing the v h ratios as a function of magnitude style of faulting distance and site class is found to be appropriate and the associated aleatory variability is found to be at least as low as that obtained in other studies using more complex models the predicted ratios from the new european model are found to be in broad agreement with recent models derived from predominantly western north america data

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

empirical prediction equations for peak ground velocity derived from strong motion records from europe and the middle east peak ground velocity pgv has many applications in earthquake engineering but there are relatively few prediction equations for this parameter in comparison with the large numbers of equations for estimating peak ground accel eration and response spectral ordinates this lack of empirical equations for pgv has led to widespread use of the practice of scaling peak velocity from the 5 damped response spectral ordinate at 1 sec which is a poor substitute for direct prediction of the parameter responding to the need to provide equations for the prediction of pgv this article derives new equations using the strong motion database for the seismically active areas of europe and the middle east following a new processing of all of the records a total of 532 strong motion accelerograms recorded at distances of up to 100 km from 131 earthquakes with moment magnitudes ranging from m 5 to 7 6 are used to derive equations for both the larger and the geometric mean of the horizontal components the predictions are found to be broadly consistent with those from previous european equations and also with preliminary results from the next generation of attenuation nga project suggesting that systematic differences in ground motions from active crustal regions if any are sufficiently small not to prevent the combined use of strong motion data from southern europe western north america and other tectonically active areas of shallow crustal seismicity

paleoenvironmental implications of concentration and 13c 12c ratios of fe co3 oh in goethite from a mid latitude cenomanian laterite in southwestern minnesota abstract a mid cretaceous 95 ma laterite in southwestern minnesota contains pisolites that consist primarily of gibbsite quartz and kaolinite with smaller amounts of goethite feooh and hematite the presence of minor berthierine an fe ii sheet silicate suggests that this cenomanian laterite experienced some degree of low temperature reductive diagenesis during its burial history the prospects for extracting useful paleoenvironmental information from the pisolitic goethite were explored by studying measured mole fraction x m and 13 c m values of the fe co 3 oh component in solid solution in the goethite using the method of incremental vacuum dehydration decarbonation data arrays that occupy distinctly different domains in plots of 13 c m vs 1 x m suggest the existence of two generations of goethite in the pisolites the apparently younger generation of goethite generation 2 evolves co 2 at 170 c while the older generation generation 1 evolves co 2 at 220 c the distribution of the data suggests that generation 2 goethite is a proxy for mixing of co 2 from three distinct co 2 sources in an oxidative environment which post dated the reductive diagenesis the small amount of generation 1 goethite seems to have persisted through the reductive diagenesis and nine of the generation 1 goethite data appear to define a proxy two endmember soil co 2 mixing line such two component mixing is consistent with expectations for a highly evolved carbonate free laterite i e the pre diagenetic cenomanian weathering system the 13 c m values of these nine data points range from 23 1 to 13 7 whereas x m values range from 0 0007 to 0 0222 linear regression of these nine data yields a slope of 0 0064 which corresponds to an ancient tropospheric co 2 concentration of about 1900 ppmv isotopic data from pisolitic kaolinite indicate a paleotemperature of about 24 c at a paleolatitude of 40 n this is substantially warmer than modern continental temperatures at such latitudes and is consistent with published indications of a generally warmer mid cretaceous climate moreover the correspondence of a warmer mid cretaceous climate with the inferred relatively high concentration of cenomanian tropospheric co 2 1900 ppmv is consistent with the idea that variations of atmospheric co 2 have a relation to climate change the results of this study emphasize the importance of careful evaluation of incremental dehydration decarbonation data from natural goethites to assess the possibility that more than one generation of goethite is present in a sample however the results also indicate that the carbon isotope information recorded in admixed goethite generations may be sorted out and used in paleoenvironmental interpretations

palynologie et paleoenvironnements des episodes du sable de lotbiniere et des varves de deschaillons pleistocene superieur de la vallee du saint laurent lotbiniere sand and deschaillons varves are indicators of the drainage pattern of the st lawrence watershed which presumably occurred during the late sangamonian 5c and 5c 5b transition the pollen content of the lotbiniere sand suggests there was a picea mariana betula pinus boreal forest in the valley in the lowermost zone of the deschaillons varves the pollen is very abundant the boreal forest was progressively flooded by lake deschaillons above this zone the vegetation seems to evolve toward a picea and betula open forest the pollen of the upper contorted varves was presumably reworked from older material or transported from remote sources the following paleoenvironmental sequence is reconstructed in the st lawrence valley i lowering of the relative drainage level as indicated by the erosional disconformity in lower rythmites this phase of unknown duration is ascribed to an eustatic lowering related to a global climatic cooling ii an aggradation phase as indicated by the lo

partially nonergodic empirical ground motion models for predicting horizontal and vertical pgv pga and 5 damped linear acceleration response spectra using data from the iranian plateau we present new ground motion prediction equations gmpes to estimate horizontal and vertical strong ground motion intensity measures gmims generated by shallow active crustal earthquakes occurring within the iranian plateau to this end a dataset containing 688 records from 152 earthquakes with moment magnitudes ranging from 4 7 to 7 4 and joyner boore distances up to 250 km has been used the effects of the local site condition are taken into account using the time averaged shear wave velocities in the upper 30 m v s 30 we decided not to include the style of faulting term in the final functional form because the total standard deviation is reduced 10 by removing this term from the functional form we used a nonlinear mixed effects regression to determine the coefficients of the functional form and to separate out the between event and between station standard deviations from the total standard deviation significant standard deviation of site to site variability demonstrates that the ergodic assumption is not able to account for the spatial variability of ground motions we introduced random effects coefficients to capture regional variations between different tectonic regions of the iranian plateau such as alborz and zagros in the regression analysis to investigate the effects of regionalization on gmpes the results showed that although the effects of regional variations for considered regions are negligible at close distances they are significant at longer distances the complexity and performance of the final functional form is justified by comparing akaike and bayesian information criteria values over many trial functional forms moreover the distribution of between event site to site and event station corrected residuals demonstrates that no trends are evident implying satisfactory performance of the proposed gmpes therefore the derived gmpes can be employed to predict gmims and to do seismic hazard assessments within the iranian plateau electronic supplement 1 lists of the events and stations considered in the final dataset and derived coefficients of the functional form 1 http www bssaonline org lookup suppl doi 10 1785 0120160205 dc1

late stage 5 glacio isostatic sea in the st lawrence valley canada and united states abstract although post glacial marine sediments of late wisconsinan and early holocene age are common in eastern canada and the northeastern united states remnants of older pleistocene marine sediments are scarce a fossiliferous marine clay that predates the classical wisconsinan was recently discovered in the st lawrence valley a dominantly estuarine environment is inferred from the geochemistry of the shells 18 o 7 1 and from benthic foraminifer and ostracode assemblages the clay indicates a marine invasion cartier sea shallower and probably shorter than that during the upper late wisconsinan champlain sea episode 12 000 9 500 yr b p the pollen content shows that regional vegetation during the marine episode began as open tundra then became a betula and alnus crispa forest reached a climatic optimum with quercus corylus and abies and concluded as a pinus picea boreal forest a corrected infrared stimulated luminescence age of 98 000 9000 yr is compatible with the epimerization ratio of shells the cartier sea resulted from a post glacial glacio isostatic marine invasion in the st lawrence lowlands it probably occurred during late stage 5 and is tentatively assigned to the transition of oxygen isotope substages 5b 5a this marine episode dates to stage 5 of the preceding continental glacier which extended to middle latitudes in ne america

multiple deglaciations of the hudson bay lowlands canada since deposition of the missinaibi last integlacial formation abstract the stratigraphic record in the james and hudson bay lowlands indicates that the sequence of glacial events at the geographical center of the 12 6 10 6 km 2 laurentide ice sheet may have been more complex than hitherto imagined isoleucine epimerization ratios of in situ and transported shells recovered from till and associated marine and fluvial sediments cluster into at least 4 discrete groups two alternative explanations of the data are offered of which we strongly favor the first hypothesis 1 setting the age of the last interglacial marine incursion the bell sea at 130 000 yr b p results in a long term average diagenetic temperature for the lowlands of 0 6 c using this temperature enables us to predict the age of shells intermediate in age between the last interglaciation and the incursion of the tyrrell sea 8000 yr ago between these two interglacial marine inundations hudson bay is predicted to have been free of ice along its southern shore about 35 000 75 000 and 105 000 yr ago based on amino acid ratios from shells occurring as erratics in several superimposed tills and fluvial sediments these results suggest 1 that traditional concepts of ice sheet build up and decay must be reexamined 2 that high sea levels may have occurred during the wisconsin glaciation and 3 that a critical reappraisal is required of the open ocean 18 o record as a simple indicator of global ice volume an alternative hypothesis 2 is also examined it is based on the assumption that the 35 000 yr old deposits calculated on the basis of hypothesis 1 date from the last interglaciation this in effect indicates that the missinaibi formation commonly accepted as sediments of the last interglaciation are about 500 000 yr old and that the effective diagenetic temperature in the lowlands during approximately the last 130 000 yr has been close to 6 c we argue for rejection of this alternative hypothesis

a predictive equation for vertical to horizontal response spectral ratios in northern iran abstract the importance of the vertical component of ground motion in damage infliction on a variety of structural systems has been shown in recent years however the available models for ground motion prediction equations gmpes for this component of earthquakes are limited and most of the existing gmpes have been specifically developed for the horizontal component of ground motion alternatively in some cases it is proposed to scale the horizontal spectrum of the earthquake to the vertical one using vertical to horizontal response spectral ratios vhsrs in this work the applicability of some global and regional vhsr models for northern iran are evaluated using several existing statistical approaches the results of these evaluations show inadequate correlation between these models and the observed vhsrs in this region consequently a new vhsr model has been proposed to convert the horizontal earthquake spectrum to the vertical one in the studied region in order to determine the regression coefficients for the proposed vhsr model some 712 three component records with distances less than 300 km from the source from 79 earthquakes with the magnitude ranging from m w 4 1 to 7 3 were used regression coefficients for peak ground acceleration and pseudospectral acceleration for 5 damped systems are determined using a random effect approach a series of comparative studies on the proposed model with respect to the existing vhsrs was performed using the median residuals for the spectral periods in the 0 1 3 s range the results of such investigation show significant reduction of the variability for the proposed model at least 50 compared with the other vhsrs online material database of strong motion records

a petrological and geochemical study of the calcareous sandstone of west african marine pleistocene cap des biches senegal abstract in senegal the marine pleistocene is represented by several outcrops of calcareous sandstone slabs which underly the recent sandy shoreline south of dakar these outcrops show dissolution and recrystallization phenomena increasingly evident as one moves south they disappear at toubab dialao i e approximately 40 km from dakar the outcrop at cap des biches has been studied mainly because of the exceptional preservation of some ostrea calcitic tests which allowed isotopic u th measurements this outcrop of metric thickness was subjected to petrographic and mineralogical examination and to several geochemical analyses trace elements stable isotopes amino acids which lead to the conclusion that the base of the deposit has been preserved two u th apparent ages obtained 178 ka and 240 ka are older than the only age of the isotopic stage 5c obtained in the area a post depositional mobility of u cannot be rejected and ages may not be reliable however a minimal age considerably older than finite 14c ages previously published may be proposed eemian interglacial i e isotopic stage 5 in these environments geochemical analyses show high pleistocene sea levels of either warmer and or more diluted waters than the present levels i e a probable northern extension of guinean waters

luminescence dating of interglacial coastal depositional systems recent developments and future avenues of research abstract luminescence dating offers new opportunities to explore the evolution of quaternary marine coastal facies and landforms this review highlights the main advances in luminescence geochronology of interglacial coastal sediments through the analysis of 547 luminescence ages most of which were published during the last decade the majority of these reported luminescence investigations have been carried out along passive margin coasts since the turn of the century the discovery of a normalization procedure known as single aliquot regeneration sar has drastically reduced data scatter and improved precision with the consequence that quartz sar optically stimulated luminescence osl has become the dating protocol of choice for the last interglacial lig period a more complex technique known as thermally transferred osl tt osl is presumably proposed for dating older interglacials of the mid pleistocene and beyond feldspar luminescence is increasingly being applied to dating pleistocene sea level high stands due to a much higher dose saturation level than quartz osl the use of feldspar irsl infrared stimulated luminescence is limited by the occurrence of variable but ubiquitous anomalous fading af following the advent of af correction methods several middle pleistocene sites have been amenable to dating albeit with significant related uncertainties recently new protocols involving the measurement of post ir irsl at elevated temperatures have yielded relatively coherent ages for interglacial sediments up to ca 300 ka quartz osl tt osl af corrected irsl and post ir irsl ages are generally correlated with periods of sea level high stands a few ages are reported from the early and middle part of the middle pleistocene as mis11 9 and more commonly mis7 high stands are documented in strongly uplifting active margin coasts however by far the most obvious age peak corresponds to the end of the lig the mis5e shoreline is probably the most studied and luminescence dated coastal feature of all as the chronology of the sea level markers is crucial to assess global eustatic sea level variations through the course of the last interglacial nevertheless the observed abundance of young 100 120 ka luminescence ages for presumed mis5e sediments may underline methodological issues and or reflect the higher preservation potential of late regressive sequences on the other hand the occurrence of geographically distant reports of mis5a high stand might reflect a true eustatic origin for this event age analysis supports the impression of general reliability of luminescence for the timing of former sea level high stands there is a clear need to address issues in dose rate variability in the phenomenology of fading in feldspar and in the behaviour of luminescence growth with dose both in laboratory and natural conditions these could be addressed and properly evaluated by dating different minerals as multiple or single grains with consequent variable internal dose rates more robust practices in the application of luminescence dating techniques could eventually constrain the age uncertainties to no better than 2 3 therefore the strength of luminescence as a dating tool is more in terms of its extended age range and the ubiquity of datable material

initiation of the last glaciation in northern europe abstract the bio and chronostratigraphy of the eemian interglacial marine isotope substage 5e and an early weichselian glaciation 5d a established from representative and detailed sequences can be correlated with the deep sea oxygen isotope stratigraphy ice core data sea level fluctuations and coupled ice sheet climate models biostratigraphic sequences from fennoscandian key sections are correlated with reference sequences from estonia and from sections located near or beyond the margins of the last glaciation organic sediments previously attributed to early and middle weichselian interstadial periods in finland are argued to be redeposited and mixed older last interglacial material pollen and diatom spectra of the undisturbed materials suggest that the eemian climatic optimum was followed by a continuously cooling climate and a regressive marine level if only undisturbed sequences are considered the major climatic fluctuations of the early weichselian apparent in central and western europe are not apparent in the sequences from the central part of the glaciated terrain instead some sequences are truncated by sediments indicating approaching ice sheets soon after the interglacial this may imply that the ice sheet grew over finland during the first early weichselian stadial the preservation of the interglacial beds and the lack of younger non glacial sediments support the interpretation that the area remained ice covered until the final deglaciation during the early weichselian the norwegian coast was probably occasionally ice free similar to the coastal zone of greenland today the authors interpretation of the fennoscandian organic deposits of the last glaciation may also explain similar observations from the central parts of the laurentide ice sheet

comparison of tl and irsl age estimates of feldspar coarse grains from waterlain sediments abstract the infrared stimulated luminescence irsl and thermoluminescence tl dating methods are applied to alkali feldspar coarse grains from shallow marine estuarine shallow lacustrine and sublittoral sediments in the range 10 200 ka no significant difference was observed between the equivalent doses obtained using irsl and tl most luminescence dates are consistent with the expected geological age estimates obtained from radiocarbon amino acid and esr dates this study provides evidence of the reliability of irsl age estimates on alkali feldspars from well bleached waterlain sediments older than 100 ka provided that a correction for long term thermal stability is applied in each case

estimation of response spectra and simulation of nonstationary earthquake ground motions abstract italian strong motion data were used to study the attenuation of response spectra and to simulate artificial accelerograms as a function of magnitude distance and site geology the database has already been utilized for the study of the atten uation of peak ground acceleration pga and velocity and consists of 95 accelero grams from 17 earthquakes of magnitudes ranging from 4 6 to 6 8 using multiple regressions we developed empirical predictive equations for the vertical and hori zontal components of response spectra corresponding to 14 frequencies ranging from 0 25 to 25 hz predictive equations aimed at the ground motion simulation were also estimated for time dependent frequency parameters strong ground motion du ration and arias intensity the shape of the predicted spectra is strongly dependent on magnitude and nearly independent of distance alluvium sites show an amplification effect with respect to stiff sites in different frequency ranges according to the thickness of the soil deposit the vertical horizontal spectral ratio in far field varies with magnitude and frequency from 0 35 to 0 85 the resulting response spectra are compared with the predictions of some recent attenuation relationships and with those proposed by the eurocode ec8 the simulation of nonstationary strong ground motions is achieved through an empirical method where time and frequency features of the motion are represented through the physical spectrum extending the spectral moments theory to the nonsta tionary case the simulated time histories fit the recorded accelerograms in terms of several ground motion amplitude measures such as peak acceleration peak velocity fourier spectra and response spectra the principal advantage of the proposed method consists in correlating the simulation parameters with earthquake magnitude source distance and soil conditions introduction in the field of seismic risk assessment the prediction of shaking intensity in future earthquakes plays a key role re liable estimates of the ground motions that structures must be designed to withstand are obtained mainly through em pirical predictive relationships developed after statistical analysis of data recorded during strong earthquakes many predictive equations are by now available in dif ferent regions of the world campbell 1985 1993 for the prediction of peak ground acceleration pga many fewer are the relationships developed for the prediction of response spectral values idriss 1991 boore

aminostratigraphy of european marine interglacial deposits molluscan fossils collected from shallow water marine sediment across nw europe and nearby arctic regions have been analysed for the extent of isoleucine epimerization dl ratio in indigenous protein residues the dl ratios confirm that essentially all classical eemian sites from nw europe are of the same age and are correlative with the type locality near amersfoort in the netherlands shells from interglacial marine sediment beneath the type weichselian till in poland also correlate with the type eemian site dl ratios in holsteinian marine shells 0 29 are substantially higher than in their eemian counterparts 0 17 late cromerian shells yield even higher ratios 0 46 dl ratios in late glacial shells 0 06 and middle weichselian shells 0 09 permit differentiation from modern 0 01 and last interglacial material based on the position of the matuyama brunhes boundary and the differences in dl ratios the eemian must correlate with isotope substage 5e whereas the holsteinian is most likely substage 7c possibly stage 9 but certainly younger than stage 11 intra saalian warm periods may be terrestrial equivalents of the younger substages of stage 7 extensive pre eemian marine sediments along the sw coast of denmark previously correlated with the holsteinian are shown to be of late cromerian age the underlying till there is the first widespread evidence of a pre elsterian till in nw europe dl ratios in molluscs from last interglacial sites along the arctic coast of the ussr the arctic islands and eastern greenland are substantially lower than in their european counterparts due to their low thermal histories the combined mid and high latitude data are used to develop a predictive model for the expected dl ratio in any of several moderate epimerization rate taxa for last interglacial sites with mean temperatures between 20 and 15 c not all sites could be unambiguously assigned to an established interglacial the fjosanger norway and margareteberg sweden sites previously thought to be eemian yield dl ratios higher than in secure nearby eemian material it is yet unresolved whether these are aberrant sites or if they predate the last interglacial in situ shoreline deposits encountered in borings in sw belgium and in exposures on the belgium coastal plain contain molluscs that yield dl ratios intermediate between secure eemian and late weichselian ratios raising the possibility that a late stage 5 high sea level event attained near modern levels in the southern north sea basin resolution of these uncertainties is the focus of future work

sequence de la transition illinoien sangamonien forage iac 91 de l ile aux coudres estuaire moyen du saint laurent quebec a series of pleistocene deposits extending over 155 m below sea level was drilled at aux coudres island in the middle st lawrence estuary quebec the series which basis is unknown is divided into two sedimentary units the lower baie saint paul glacial complex facies 155 to 125 m which is correlated with the illinoian isotopic stage 6 and a stratified sequence referred to as the ile aux coudres formation the latter is subdivided into four zones a very compact lower clay 125 to 102 m rhythmites with paleozoic schist debris 102 to 71 m and prodeltaic silts and deltaic sandy silts with brackish water benthic foraminifera 71 to 2 m the spore and pollen content indicates a schrub tundra followed by an afforestation sequence of a boreal forest that changes to an abies forest and then to an interglacial mixed forest with betula jugions carpinus or ostrya carya and at the top betula tsuga quercus and ulmus the accumulation of the sediments of the ile aux coudres formation required approximately 3500 years beginning with a deep marine environment about 300 m followed by shallowing waters during the subsequent glacioisostatic rebound phase of the regression the sedimentation is assigned to a main postglacial marine invasion referred to as the guettard sea which occurred prior to two regional glacial episodes and was partly contemporaneous with bell sea invasion in the hudson bay lowlands a major postglacial sedimentary influx in the atlantic ocean during the illinoian sangamonian transition and at the beginning of the sangamonian transition 6 5 and early substage 5e is inferred from this marine event

possible atmospheric co2 extremes of the middle cretaceous late albian turonian 1 atmospheric carbon dioxide co2 estimates for the middle cretaceous mk have a range of 4000 ppm which presents considerable uncertainty in understanding the possible causes of warmth for this interval this paper examines the problem of mk greenhouse forcing from an inverse perspective we estimate upper ocean water temperatures from oxygen isotope measurements of well preserved late albian turonian planktonic foraminifera and compare these against temperatures predicted by general circulation model gcm experiments with co2 concentrations of 500 7500 ppm at least 4500 ppm co2 is required to match maximum temperatures inferred from well preserved planktonic foraminifera approximately 900 ppm co2 produces a good match between the model and the minimum temperature estimates for the mk an ocean model forced by these two extremes in surface conditions brackets nearly all available bottom water temperature estimates for this interval the climate model results support nearly the entire range of mk co2 estimates from proxy data the ocean model suggests possible mk oceanographic changes from deep water formation in the high latitude region of one hemisphere to the other hemisphere in response to changes in atmospheric temperatures and hydrologic cycle strength we suggest that rather than contradicting one another the various proxy co2 techniques especially those with high temporal resolution may capture true variability in co2 concentrations and that mk co2 could have varied by several thousand ppm through this interval

smooth spectra of horizontal and vertical ground motions an improved method of constructing a smooth response spectrum from peak values of ground acceleration velocity and displacement pga pgv and pgd is presented improved dynamic amplification factors are presented for applying damping adjustments to the spectral accelerations or to backcalculate pga pgv and pgd from spectral accelerations horizontal to vertical spectral ratios are analyzed for rock and soil sites to allow the construction of a vertical design spectrum from a given horizontal design spectrum

postglacial palaeophytogeography of the eastern st lawrence river watershed and the climatic signal of the pollen record abstract pollen analytical studies of the sediments of over 150 lakes and bogs in southern quebec have led to the indentification of a limited number of sequential types or temporal suites of the various pollen assemblages within each of three main stages of the postglacial development of vegetation the non arboreal stage the afforestation stage and the forest stage these sequential types within any of the three stages show distinct geographical and chronological distributions in southern quebec during the last 12 000 yr when compared in a broader geographic context they demonstrate a strong differentiation of the pollen record within and around the great lakes st lawrence river watershed during the last 15 000 yr b p amongst the most striking gradients identified stand the late glacial perichamplainian gradients ca 11 500 10 000 yr b p and the early holocene gradients the former involve seaward and northeastward clines from closed coniferous forests to tundras and the latter northeastward changes in the nature and duration of the afforestation stage the modern pattern of even the broader vegetational gradients in southern quebec was not attained before 3000 yr b p palynological reconstruction of the various regional paleoclimates highlights the interaction of local regional and global climatic forcings through time mesoscale climate modelling and palaeoclimatology should find boundary conditions in those regional reconstructions

a predictive equation for the vertical to horizontal ratio of ground motion at rock sites based on shear wave velocity profiles from japan and switzerland abstract ratios of vertical to horizontal v h ground motion are important for the computation of scenario compatible vertical design spectra they are therefore a crucial aspect of seismic hazard analysis we characterize the v h ratio at rock sites in terms of the recording site s average quarter wavelength velocity a predictive equation is presented which can be used for reconstructing the expected v h ratio of the 5 damped response and fourier spectra for rock sites given a known shear wave velocity profile the equation is based on the regression analysis of two datasets one from switzerland and one from japan the two datasets allow us to analyze well characterized hard rock sites in switzerland using small earthquakes m w 2 while the magnitude range is increased up to events of m w 7 3 using strong motion recordings from japan s kik net seismic network it is shown that a correlation exists between the quarter wavelength velocity at a given frequency and the v h ground motion ratio small differences possibly due to velocity measurement bias or topographical and basin effects existed when analyzing the individual regional datasets apart from near source distances r v h no clear magnitude or distance dependence of the v h ratios is present in either of the datasets of earthquake recordings we show that the same correlation exists for response spectra and fourier spectra of recorded ground motion a similar correlation was derived for ambient vibrations recorded at swiss station sites resulting in larger values of v h at a given frequency and thereby indicating that v h is sensitive to the composition of the wave field finally uncertainties in the v h models are presented we separate the sources of uncertainty into source and site specific components and present the single site sigma uncertainty measure for site specific hazard analyses

ground motion characterization for vertical ground motions in turkey part 1 v h ratio ground motion models two approaches are used to develop the vertical design spectra in probabilistic seismic hazard assessment psha i performing psha for the vertical component using vertical ground motion models gmms and ii utilizing the v h ratio gmms to scale the horizontal spectrum during or after the hazard calculations for the horizontal component this study intends to develop a new framework for building a vertical ground motion logic tree that combines both vertical and v h ratio gmms in the psha analysis for this purpose the turkish strong motion database tsmd akkar et al in journal of seismology 14 3 457 479 2010 is updated with recordings from earthquakes that occurred between 2008 and 2015 including the mw 6 1 elazig and mw 7 2 van earthquakes the updated tsmd contains 2698 recordings with the earthquake metadata source to site distance metrics for the recordings measured shear wave velocity profiles for the recording stations and spectral accelerations for horizontal and vertical components four candidate v h ratio gmms proposed by gulerce and abrahamson in earthquake spectra 27 4 1023 1047 2011 gulerce and akyuz in seismological research letters 84 4 678 687 2013 akkar et al in bulletin of earthquake engineering 12 1 517 547 2014a bozorgnia and campbell in earthquake spectra 32 2 951 978 2016 are selected and the model predictions are compared with the actual data in the updated tsmd using the analysis of the residuals and data driven techniques analysis results showed that the median predictions of the v h ratio gmms proposed by gulerce and akyuz 2013 akkar et al 2014a and bozorgnia and campbell 2016 are compatible with the v h ratios in the turkish strong motion dataset the findings of this study and the compatibility analysis of the vertical gmms with the updated tsmd are combined in the accompanying manuscript gulerce et al in pure and applied geopyhsics 2019 submitted to provide the complete framework of ground motion characterization for vertical ground motion component

pleistocene palynostratigraphy in the st lawrence valley and middle estuary the litho biostratigraphic framework of the upper middle and upper quaternary units of the st lawrence basin results from the interplay of ice advance retreat isostatic depression rebound fluvial processes and climatic changes each main climatic cycle is characterized by a sedimentary sequence representative of the associated changing depositional environments the climatic significance of the units is assessed with reference to the pollen content and the evolving trend of the inferred vegetation five assemblages are defined 1 the mixed woods assemblage related to temperate deciduous forests 2 the boreal forest subdivided into a balsam fir a balsamea dominated assemblage a pine p banksiana or p divaricata dominated assemblage and a spruce dominated assemblage picea mariana 3 the forest tundra subarctic zone 4 the shrub tundra with subarctic plants and 5 the herb tundra arctic zone three marine invasions older than late wisconsinan record a progressive vegetal recolonization a pre illinoian marine episode the post illinoian marine invasion of guettard sea 6 5 transition and the cartier sea invasion substage 5b three types of lake inundated the lowlands 1 lake systems associated with interstadial or interglacial fluvial drainage 2 deglacial lakes with a gradual vegetal recolonization 3 pre glacial lakes whose pollen indicates boreal forest replacement by forest tundra and herb tundra

quaternary basin analysis using infrared stimulated luminescence on borehole cores and cuttings abstract numerous boreholes have been drilled in the st lawrence lowland for the purposes of detecting the presence of natural gas and to set up the regional quaternary stratigraphy since the recovery of most of the samples is composed of cuttings the lithological and sedimentological features are not preserved and cannot be used as stratigraphic indicators a new stratigraphic correlation tool based on the relative depositional age is proposed using irsl this study shows that a luminescence parameter r defined as the ratio of increase of luminescence upon added dose can discriminate sediments of different age and be used as a correlation tool in sedimentary basin analysis this approach has been tested on sediments collected along river sections continuous drill cores and cuttings

glacially influenced late pleistocene stratigraphy of a passive margin new jersey s record of the north american ice sheet abstract glacial isostasy and the sediment supply changes associated with the waxing and waning of ice sheets have dramatic effects on the stratigraphy of adjacent continental shelves in ancient stratigraphic records the glacial influences on such deposits could be difficult to recognize because of the removal of coeval terrestrial glacial deposits by erosion this study illustrates the effects of the laurentide ice sheet on a basin near its maximum limit the new jersey continental shelf analysis of 1600 km of geopulse uniboom minisparker and airgun profiles reveals four depositional sequences that have a maximum thickness of 75 m near the shelf edge sequences i and iv correspond to the major glacial interglacial sea level changes at marine isotope chron mic 6 5e and 2 1 whereas sequences ii and iii reflect smaller scale sea level fluctuations during chrons 4 3c and 3b 3a respectively sequences i and iv are characterized by relatively thick low stand to early transgressive deposits near the shelf edge formed during times of increased sediment supply but are thin and discontinuous across much of the shelf reflection horizons in these units deepen northward in the northern half of the study area due to collapse of a peripheral bulge that formed at the margin of the laurentide ice sheet the hudson river moved from a more southerly drainage pattern to the modern hudson shelf valley position possibly under the influence of the advancing peripheral bulge sequences ii and iii are largely preserved within a broad mid shelf swale likely created by the migration of an ancestral hudson river and their thickness implies much higher sedimentation rates during chrons 4 and 3 than seen today if the terrestrial glacial record was eroded the increased rates of sedimentation during the pleistocene dominance of sediments derived from northern new england and northward tilting of strata could be interpreted as a result of uplift of a northern source area the unusually high frequency of the relative sea level oscillations 20 kyr the concentration of sediment supply during low stands and early transgressions and the correspondence of sea level change with climatic change could be used to infer their relationship to a nearby ice sheet geologists studying deposits formed during times of widespread continental glaciation should consider possible glacial influences on the stratigraphy of mid latitude deposits even in the absence of sediments directly deposited by ice

contribution palynostratigraphique dinokystes pollen et spores a la connaissance de la mer de champlain coupe de saint cesaire quebec high resolution continental pollen and spores and marine dinoflagellate cysts microfloral records were obtained from a section consisting of about 0 5 m of glaciolacustrine and 2 5 m of champlain sea deposits at the saint cesaire site the pollen and spore assemblages indicate the existence of a regional open vegetation of shrub tundra to forest tundra fluctuations in the percentages of picea and shrub and herb taxa are related to regional afforestation and paleogeographical evolution of the basin the champlain sea sediments contain an abundant dinocyst flora dominated by operculodinium centrocarpum brigantedinium spp and algidasphaeridium minutum which indicate cold arctic conditions in surface waters fluctuations in concentration 102 104 cm 3 and relative abundance of dinocyst species are attributed to changes in dinoflagellate productivity and paleoceanographic conditions notably paleosalinity morphological variations of operculodinium centrocarpum and algidasphaeridium minutum led to

topography effect at the critical sv wave incidence possible explanation of damage pattern by the whittier narrows california earthquake of 1 october 1987 abstract buildings damaged by the whittier narrows california earthquake of 1 october 1987 were concentrated in several areas most of which were located 8 to 10 km from the epicenter corresponding to the critical incidence for sv waves and were near topographic irregularities such as the northern part of whittier just south of puente hills the purpose of this study is to show the possibility that this anomalous damage pattern is due to the amplification by the topographic irregularity when sv waves are near critical incidence first we examined the accelerograms obtained at the usgs station 7215 bright ave nearest to downtown whittier and conclude that the dominantly eastwest motion observed at the station is due to the influence of the building in which accelerograms were recorded we next demonstrate that strong ground motions recorded by 12 stations in the epicentral area show a polarization direction pattern that is primarily sv type which is consistent with a simple thrust fault located at the hypocenter then we calculated the response of a two dimensional hill with the height 0 3 km and the width 2 4 km to 1 a plane sv wave with a nearly critical angle of incidence 2 a horizontal line force 3 a haskell type 2d dislocation source and 4 a bouchon type 2d multiple crack source the results show that the amplification due to the hill relative to the flat surface is more than 1 5 for all the source models since this amplification is nearly independent of the source type and spectrum we conclude that the combined effect of the topographic irregularity and critically incident sv waves might be responsible for the concentration of damage observed during the whittier narrows earthquake

ground motion prediction model for vertical response spectra from mexican interplate earthquakes abstract we present ground motion prediction equations gmpes for vertical response spectra from mexican interplate earthquakes at rock sites national earthquake hazards reduction program b class two options to obtain the vertical response spectrum are presented 1 directly from the vertical attenuation model and 2 by multiplying the horizontal spectral ordinates by the vertical to horizontal ratios the equations were built as functions of magnitude and distance to the fault surface of the earthquake using 40 interplate earthquakes we compared our results with previous attenuation models for inslab and interplate earthquakes in mexico and other vertical attenuation models in the world the predicted intensities from the model were found to be in broad agreement with models derived with other models worldwide not many vertical and or vertical to horizontal attenuation models were found in the literature although the vertical response of structures is used in practice and included in design codes nevertheless it seems to be a trend to pay more attention to this model there was also found to be a lack of gmpes for vertical response spectra applicable to subduction interplate earthquakes for a large range of distances and the region under study therefore an attenuation model for interplate earthquakes was developed for distances up to around 400 km and m w from 5 to 8 the model could be useful for probabilistic seismic hazard assessment and as an aid for code writers

characterizing the vertical to horizontal ratio of ground motion at soft sediment sites a predictive equation to obtain the vertical to horizontal ratio v h of ground motion for rock sites has been established in a previous article the method was based on the comparison between v h of fourier and response spectra of earthquakes with the quarter wavelength average velocity at discrete frequencies we extend this approach to account for resonance phenomena at soft sediment sites in order to do so a new parameter is defined and included in the comparison with the v h spectra the new parameter is directly derived from the quarter wavelength velocity and represents the frequency dependent seismic impedance contrast at the site we show that extending the correlation in this three dimensional space is beneficial to reconstruct v h of the 5 damped response spectra at soft sediment sites v s 30 800 m s for which a shear wave velocity profile is available in this study we analyze 220 sites of the japanese kik net strong motion network these sites were selected from the entire network through comparison of the fundamental frequencies estimated from the recordings and by indirect modeling methods from the analysis two types of predictive equations are then established the first based on frequency dependent and the second on frequency independent correlations these can subsequently be used to reconstruct the v h spectrum at any site with a known shear wave velocity profile for both equations uncertainties of the v h models are provided and a sensitivity study to magnitude distance dependence is presented finally we show an example of the application of the model at four selected soft sediment sites of the swiss seismic network

a stochastic ground motion model for switzerland abstract we present a stochastic ground motion model for switzerland a model for the far field fourier amplitude spectra of earthquakes is first proposed constrained by ground motions observed from small local and regional earthquakes in addition to macroseismic intensities observed from large damaging events in switzerland we then use this model in a stochastic simulation technique to generate predictions of peak ground acceleration and velocity and 5 damped response pseudo spectral acceleration we facilitate the prediction of ground motions from finite fault sources through the use of the r eff distance metric and show that magnitude and distance scaling behavior of events up to m w 7 5 is broadly consistent with next generation attenuation and japanese models ground motion prediction uncertainty is described in terms of between and within event uncertainties through residual analysis of response spectra finally single station sigma is derived accounting for the prediction uncertainty at a given site without the ergodic assumption consistency of the model is emphasized through its compatibility with other seismic hazard products the model is referenced to a generic rock profile that was developed by utilizing velocity profiles of the sites of seismic stations and is calibrated at higher magnitudes to the swiss regional macroseismic intensity prediction model furthermore the model is based on moment magnitudes from the recently developed earthquake catalogue of switzerland 2009 ecos09 the well defined reference for the model means that it can easily be adapted for a site specific application for instance through the use of proxies such as quarter wavelength velocity and travel time average shear wave velocity in the upper 30 m v s 30

properties of vertical ground motions a typical engineering approach to developing site specific design vertical ground motions starts with rock outcrop horizontal motions converts them into the vertical component using an empirical vertical to horizontal v h ratio for response spectra and propagates the resulting motion through the soil column as a vertically incident p wave in the absence of data on strain dependent soil properties in compressional deformation strain compatible shear wave properties from the horizontal component analyses are utilized this approach makes two assumptions 1 that the vertical motions are primarily composed of compressional waves and 2 that strain dependent material properties in shear deformation can be extrapolated to compressional deformation our study deals with the empirical validation of both assumptions first we investigated the ratio of sv to p wave spectra of the vertical component of ground motions from significant recent events in california to find which wave type predominantly contributed to vertical motions in the frequency range of 0 5 25 hz the results indicate that shear waves dominate the vertical motions at frequencies up to approximately 10 hz above which the contribution of compressional deformation is about as strong or greater this result holds for both soil and rock sites second using the data from the kik net borehole arrays in japan we estimated the nonlinearity in compressional deformation by studying p wave amplification at variable amplitude levels frequency shifts and in some instances reduced amplification compatible with the hysteretic softening type of nonlinearity known for shear waves is found as the amplitude of compressional strain increases a tentative curve of constrained modulus reduction is also similar to the existing shear modulus reduction curves the results of this study suggest that for most practical applications vertical motions can be modeled as nonvertically propagating sv waves this could be implemented through conventional one dimensional horizontal component modeling using shake and the application of empirical depth dependent v h correction factors to account for the inclined propagation path at high frequencies vertical motions may have to be modeled as near vertically propagating p waves with strain dependent properties specifically developed for compressional deformation however these frequencies may be of lesser importance for design applications manuscript received 11 january 2002