equivalent point source modeling of moderate to large magnitude earthquakes and associated ground motion saturation effects we modeled the source and attenuation attributes of well recorded m6 earthquakes based on the equivalent point source approach with the goal of determin ing how to treat ground motion saturation effects within this context we consider ground motions as originating from an equivalent point source and mimic finite fault effects by treating the motion as emanating from a virtual point not a real point on the fault rupture such that ground motions are correctly predicted at close distances this is achieved by using an effective distance metric r d 2 h 2 0 5 in which drup is the closest distance to the rupture and h is a pseudodepth term that accounts for sat uration effects we found that the distance saturation effect is magnitude dependent extending to further distances with increasing magnitude for earthquakes of m 6 we model the saturation term as logh 1 72 0 43 m with a standard deviation of 0 19 in log10 units based on the values obtained from the study earthquakes the apparent source spectra of most m6 earthquakes can be modeled using a simple brune point source model for a few of the m6 earthquakes notably those in california we observed a spectral sag at intermediate frequencies for such earth quakes a two corner point source model provides a better match than the brune model we conclude that an equivalent point source model based on the effective distance concept can successfully predict the average ground motions from m6 earthquakes over a wide distance range including close distances 20 km

the ultimate undrained resistance of partially embedded pipelines on bottom pipelines for transporting oil and gas in deep water undergo significant changes in temperature and pressure during operating cycles which cause a tendency for lateral buckling prediction and control of this phenomenon are required for the safe design and operation of these pipelines however the soil response under combined vertical and lateral loading is a significant area of uncertainty and current practice relies on empirical expressions for the estimation of lateral pipe soil resistance this paper reports the results of finite element fe analyses of shallowly embedded pipelines under vertical and horizontal load these analyses have been compared with collapse loads calculated using the upper bound theorem of plasticity and are used to construct yield envelopes defining the limiting combinations of vertical and horizontal load the fe limiting loads were found to compare well with upper bound plasticity solutions and the internal soil displacements calculated in the fe analyses mat

surface materials on unusual planetary object chiron abstract we present the first jhk near infrared colorimetry giving some indication of the surface materials on the peculiar object 2060 chiron the colors appear to exclude relatively clean bright ice surfaces such as those of europa ganymede rhea dione and theoretically studied micronscale clean ice particles the colors are consistent with those of numerous outer solar system asteroids which in all measured cases have albedos of only a few percent c rd or dm type spectra and no known h 2 o ice absorption features the colors are also consistent with theoretical colors for certain size distributions of dirty ice grains these and additional vjhk colorimetric data suggest that the spectrally dominant surface is c type material probably dark carbonaceous like silicate dust with a possible admixture of ice grains on a microscale if chiron has the low albedo common to such material on known interplanetary bodies its diameter would be about 310 to 400 km placing chiron among the eight largest asteroids relationships to comet observations are discussed

settlements of shallow foundations on sand a method to evaluate settlements and rotations of rigid shallow foundations on sand under the combined action of inclined and eccentric loads is presented experimental results obtained on a model strip foundation are shown first next a mathematical model is formulated which is based on the hypotheses that a the foundation and the soil can be considered as a macro element for which the loadings act as generalized stress variables while the displacements and rotation of the foundation are the corresponding generalized strain variables and b the constitutive law of the macro element that is the relationship between generalized stress and strain rates is rigid plastic strain hardening with a non associated flow rule constitutive functions and parameters are determined by means of simple calibration tests predictions of the theory are then compared with experimental results in tests where loadings vary in a complex way up to foundation failure it is shown that experimental evidence is well matched

effects of bond crushing on the settlements of shallow foundations on soft rocks the paper presents a model capable of describing the behaviour of shallow foundations on soft rocks when subjected to eccentric loading the model is based on the concept of a macroelement according to this concept the foundation and the subsoil can be seen as a unique volume element a mathematical relationship is established that links the force and moment acting on the foundation and the corresponding displacement and rotation as if they were generalised stresses and strains respectively this relationship is based on the theory of hardening plasticity with two hardening variables both functions of the permanent generalised strains it is assumed that the second of such variables connected to the action of intergranular bonds monotonically decreases as strains progress and bonds crush it is shown that the model can reproduce quite well the observed displacement and rotation of a model circular foundation on a layer of calcarenite a parametric study also highlights that the model can in prin

cemented sands under static loading cemented sands are found in many areas of the world one of their distinguishing characteristics is their ability to stand in steep natural slopes large deposits are located along the california coast and in a number of areas intense urban development has occurred near the crest of high steep slopes because of the hazards posed by slope failures in the cemented sands a test program was undertaken to define the nature of the cementation and its effect on behavior of the soils a total of 137 laboratory compression and tension load tests were performed on undisturbed samples of naturally cemented sands and artificially prepared cemented sands the materials exhibited friction angles similar to uncemented sands but had a cementation strength intercept and a tensile strength the primary cementing agents of the sands tested were silicates and iron oxides the strength of the cemented sands were found to be a function of density amount of cementing agent grain shape and grain arrangement

combined loading of spudcan foundations on clay laboratory tests recent research has shown that work hardening plasticity theory provides a suitable framework for interpreting and predicting the load displacement behaviour of rigid shallow foundations under combined vertical moment and horizontal loading most previous work has however been restricted to footings on granular soils this paper describes a series of laboratory tests conducted at unit gravity using a small circular footing and specimens of reconstituted kaolin the results indicate that work hardening plasticity concepts can also be applied to the modelling of shallow foundation behaviour on undrained clay the footing shape chosen for the experiments is representative of the spudcan foundations which support the legs of jack up drilling platforms a novel testing apparatus allows independent control of the vertical rotational and horizontal footing displacements within a single vertical plane tests conducted at constant vertical penetration are used to investigate the shape and size of the combine

inverse analysis based interpretation of sand behavior from triaxial compression tests subjected to full end restraint current laboratory testing often imposes or assumes uniform stress and strain distribution in a specimen for convenient data reduction to interpret soil behavior this paper presents an inverse analysis framework self learning simulations selfsim to interpret the drained behavior of sand from triaxial compression tests with fully frictional loading platens the frictional platens result in significant bulging of and nonuniform stresses and strains within sand specimens selfsim treats the specimen as a boundary value problem bvp and extracts these nonuniform stresses and strains from within each specimen using external load and displacement measurements the extracted behavior shows significant principal stress rotation variation of intermediate principal stress and nonuniform volume change throughout the specimen mobilized friction angles are interpreted on the two dimensional slip surface associated with the mohr coulomb failure criterion on the octahedral plane associated with the drucker pra

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

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

test of goodness of the nga ground motion equations to predict the strong motions of the 2012 ahar varzaghan dual earthquakes in northwestern iran in the first part of this study a set of 87 ground motion records with closest distance to the rupture plane r rup less than 200 km and averaged shear wave velocity over the top 30 m of the subsurface v s 30 between 175 and 1400 m s recorded during the 2012 ahar varzaghan dual earthquakes m w1 6 4 m w2 6 3 were taken into account to examine the predictive capabilities of the next generation attenuation nga ground motion prediction equations gmpes via a set of comparative analyses and tests the first applied method to assess the performance of the nga gmpes is based on the intraevent residual analysis the primary database i e 87 records was also used to develop an event specific gmpe in the case of the ahar varzaghan dual earthquakes by means of regression analyses the derived event specific gmpe has been compared with the nga gmpes for two different site conditions that is v s 30 375 m s rock site and v s 30 375 m s soil site the residual analysis results indicate that the nga gmpes perform better in predicting data recorded at rock sites compared to soil sites for soil sites and at large periods t 2 0 s the observed spectral accelerations are overpredicted by the nga gmpes furthermore as the second part of this study to select the most adequate gmpes 14 strong motion records from the 1997 ardebil earthquake m w 6 1 were added to the primary database the implementation of the likelihood lh and log likelihood methods as modern lh based ranking assessment techniques as well as the nash sutcliffe index reveal that the nga gmpes show good compatibility at short medium periods t 1 0 s on the basis of the data recorded during the 2012 ahar varzaghan dual and 1997 ardebil earthquakes i e 101 records however in the long period range the dispersion in the data does not allow the authors to draw a comprehensible conclusion

a comparison of nga ground motion prediction equations to italian data abstract ground motion prediction equations gmpes have recently been developed in the next generation attenuation nga project for application to shallow crustal earthquakes in tectonically active regions we investigate the compatibility of those models with respect to magnitude scaling distance scaling and site scaling implied by italian strong motion data this is of interest because 1 the italian data are principally from earthquakes in extensional regions that are poorly represented in the nga dataset and 2 past practice in italy has been to use local gmpes based on limited datasets that cannot resolve many significant source path and site effects we find that the magnitude scaling implied by the italian data is compatible with four nga relations however the italian data attenuate faster than implied by the four ngagmpes at short periods the differences are statistically significant comparison with the fifth one was not possible because it was developed for rock conditions only three regression coefficients are reevaluated for the four ngagmpes to reflect the faster attenuation a constant term a term controlling the slope of distance attenuation and a source fictitious depth term the scaling of ground motion with respect to site shear wave velocity is consistent between the nga models and italian data moreover the data are found to contain a nonlinear site effect that is generally compatible with nga site terms the intraevent scatter of italian data is higher than in the nga models although interevent scatter is comparable to nga recommendations when the faster distance attenuation is considered on the basis of these findings we recommend using the nga relations with the aforementioned minor modifications to evaluate ground motions for seismic hazard analysis in italy

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 complete three dimensional failure envelope for shallow footings on sand this paper considers the possibility of constructing a three dimensional failure envelope for a shallow sand supported footing earlier two dimensional work is outlined and data taken from a number of sources to produce best fit eliptical cross sections equations are then presented for a complete three dimensional failure envelope comprising a system of inclined elipses and intersecting parabolas the equations are normalised and compared with test data it is suggested that the three dimensional surface will provide a simpler method for predicting failure loads and the effect of specific combinations

dem simulations of transverse pipe soil interaction on sand realistic modelling of transverse i e vertical and lateral pipe soil interaction plays an important role in predicting the behaviour of untrenched offshore pipelines that are designed to undergo

assessment of numerical procedures for determining shallow foundation failure envelopes the failure envelope approach is commonly used to assess the capacity of shallow foundations under combined loading but there is limited published work that compares the performance of various num

a new global database of mars impact craters 1 km 1 database creation properties and parameters 1 impact craters have been used as a standard metric for a plethora of planetary applications for many decades including age dating geologic mapping and stratigraphic relationships as tracers for surface processes and as locations for sampling lower crust and upper mantle material utilizing craters for these and other investigations is significantly aided by a uniform catalog of craters across the surface of interest consequently catalogs of craters have been developed for decades for the moon and other planets we present a new global catalog of martian craters statistically complete to diameters d 1 km it contains 384 343 craters and for each crater it lists detailed positional interior morphologic ejecta morphologic and morphometric data and modification state information if it could be determined in this paper we detail how the database was created the different fields assigned and statistical uncertainties and checks in our companion paper robbins and hynek 2012 we discuss the first broad science applications and results of this work

a systematic framework for formulating convex failure envelopes in multiple loading dimensions the failure envelope approach is widely used to assess the ultimate capacity of shallow foundations for combined loading and to develop foundation macro element models failure envelopes are typic

simulation of strong ground motion in northern iran using the specific barrier model summary in this study based upon the calibrated specific barrier model sbm against the latest available strong motion data ground motion prediction equations for soil and rock sites in northern iran are developed the sbm may provide the most complete simple and self consistent description of the faulting process which is applicable in both near fault and far field regions consequently the sbm may provide consistent ground motion simulations over the entire necessary frequency range and for all distances of engineering interests to determine source parameters in this study we used 163 three component records of 32 earthquakes with magnitude ranging from mw 4 9 to 7 4 in northern iran in the database records with hypocentral distances less than 200 km are chosen and only earthquakes whose moment magnitude estimates are available have been used furthermore using the best available information recording sites are classified into two main geologic categories rock and soil because of the lack of site amplification information in the most regions of the world including iran we used the h v ratio method for estimating the site amplification moreover the kappa factor that shows diminishing the high frequency amplitude is determined in this study two data sets are considered for determining the source parameters g and l and the h v ratio and the kappa factor only s wave part of signals is used in each analysis regression analysis is performed using random effects method that considers both interseismic event to event and coseismic within event variabilities to effectively deal with the problem of weighting observations from different earthquakes the residuals are controlled against available northern iranian strong ground motion data to verify that the model predictions are unbiased and that there are no significant residual trends with magnitude and distance at first it is assumed that no sign of self similarity breakdown is observed between the source radius and its seismic moment after controlling the results the modified sbm should be used as some deviations have been observed to verify the robustness of the results the number of observations is changed by removing various randomly selected data sets from the original database which results in unchanged results of the model stochastic simulations are then implemented to predict peak ground motion and response spectra parameters the stochastic sbm predictions are in relatively good agreement with other available attenuation relationships proposed for iran europe and middle east it has been shown that the proposed sbm of this study provides unbiased ground motion estimates over the entire frequency range of most engineering applications it provides a reliable and physically realistic yet computationally efficient way to model strong ground motions

numerical investigation of bearing capacity of spudcan foundations in clay overlying sand under combined loading abstractthe evaluation of the foundation capacity under combined vertical horizontal and moment loading is an essential element of the site specific assessment that ensures mobile jackup rigs are

displacements of footings on sand under eccentric and inclined loads results of an investigation of the response of footings on sand under eccentric and inclined loads are presented apparatus was constructed that could simultaneously apply loads to footings at any eccentricity and inclination without imposing restraints on the footing displacements the experimental results are interpreted compared with published data and a method for predicting vertical and horizontal displacements and rotations of loaded footings on sand developed at low load levels the analysis generates the elastic half space solution which is then augmented to provide the complete nonlinear response of the footing in addition interaction diagrams between the vertical loads horizontal loads and moments that cause failure of the footing are presented key words footing sands eccentric loading inclined loading displacement rotation bearing capacity

testing the global applicability of ground motion prediction equations for active shallow crustal regions abstract large research initiatives such as the global earthquake model gem or the seismic hazard harmonization in europe share projects concentrate a great collaborative effort on defining a global standard for seismic hazard estimations in this context there is an increasing need for identifying ground motion prediction equations gmpes that can be applied at both global and regional scale with increasing amounts of strong motion records that are now available worldwide observational data can provide a valuable resource to tackle this question using the global dataset of allen and wald 2009 we evaluate the ability of 11 gmpes to predict ground motion in different active shallow crustal regions worldwide adopting the approach of scherbaum et al 2009 we rank these gmpes according to their likelihood of having generated the data in particular we estimate how strongly data support or reject the models with respect to the state of noninformativeness defined by a uniform weighting such rankings derived from this particular global dataset enable us to explore the potential of gmpes to predict ground motions in their host region and also in other regions depending on the magnitude and distance considered in the ranking process we particularly focus on the influence of the distribution of the testing dataset compared with the gmpe s native dataset one of the results of this study is that some nonindigenous models present a high degree of consistency with the data from a target region two models in particular demonstrated a strong power of geographically wide applicability in different geographic regions with respect to the testing dataset the models of akkar and bommer 2010 and chiou et al 2010

phoebe voyager 2 observations voyager 2 images of phoebe obtained over a period of 24 hours provide information on the size rotation rate surface markings and photometric properties of this mysterious object phoebe is approximately equidimensional its longest diameter 230 km is only 10 greater than the shortest diameter 210 km a prograde rotation period of 9 4 0 2 hours was determined from both the disk integrated light curve and by tracking individual markings because of the limited resolution of the images 11 pixels across the disk crater counts cannot be made the geometric albedo of phoebe is longitudinally variable from 0 046 to 0 060 clear filter 0 47 m the most prominent surface markings are brighter patches at high northern and southern latitudes that have reflectances as much as 50 greater than the dark bland areas these patches are scattered and do not appear to constitute polar caps the voyager color data agree with earlier ground based spectra that show that phoebe has a flatter spectrum than does the dark side of iapetus this observation is not consistent with simple contamination of iapetus by debris from phoebe

a rheological model for the description of boulder impacts on granular strata this paper considers the mechanics of rock boulders impacting on granular strata the study is aimed at improving the numerical methods devoted both to describing boulder trajectories along slopes and designing preventive structures in mountain regions the problem is analysed by using a simplified approach inspired by the lumped mass method this is based on a the macro element concept b the definition of generalised stresses and displacements and c delayed plasticity theory both vertical and inclined impacts on horizontal strata and vertical impacts on inclined slopes are discussed the numerical results are obtained by using a finite difference numerical discretisation to integrate over time a coupled system of two dimensional differential equations most of the input data requested by the model are basic and geotechnically meaningful and comparison of the numerical results with the experimental data seems to be quite promising

oedometric tests on artificially weathered carbonatic soft rocks carbonatic rocks are subject to progressive degradation of their mechanical characteristics due to weathering this phenomenon may have relevance for engineering since it can induce settlement of foundations progressive failure of slopes or an increase of pressure on tunnel liners to study weathering effects on a laboratory timescale oedometric tests have been conducted on specimens of calcarenite and artificially cemented silica sand weathering was simulated by percolating an acid solution under constant load the recorded progression of deformation over time ends with a horizontal asymptote when only bonds are destroyed cemented sand whereas it results in a steady increase when the grains are also degraded calcarenite to determine the variation in stress state induced by weathering a special oedometer was designed allowing very small lateral deformation of the ring its circumferential stretching was measured with strain gauges and correlated to the lateral pressure exerted by the specimen in all cases considered the horizontal stress increased remarkably during weathering at constant vertical load predictions of a chemoplastic constitutive model are then compared to experimental data and then show good agreement especially for cemented sand

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

pipe soil interaction model incorporating large lateral displacements in calcareous sand the use of the plasticity theory offers an attractive framework to encapsulate the behavior of a pipe and the underlying soil in terminology consistent with pipeline structural analysis models that express the pipe soil behavior purely in terms of the loads on a segment of pipe and the corresponding displacements have been suggested although verification with geotechnical centrifuge experiments has been limited to relatively small lateral displacements i e less than two pipe diameters over larger movements the berms that build up alongside the pipe affect the load displacement behavior with existing strain hardening plasticity models incapable of simulating this transition this technical note provides experimental evidence of pipe soil behavior for lateral displacements for up to five diameters it further presents observations from 20 centrifuge experiments of a prototype 1 m diameter pipe in calcareous sand the results are used to validate the modification of a pipe soil model to include the

the uranian satellites water ice on ariel and umbriel abstract new near infrared reflectance spectra are presented for ariel and umbriel water ice on the surface of ariel and umbriel is verified from spectral signatures in the 2 m region however the weaker bands in umbriel s spectrum indicate that its surface is significantly different from ariel either in degree of contamination with dark material or in microstate umbriel may have a lower albedo than ariel titania and oberon and therefore may have a diameter comparable to that of titania

simulation of ground motion in the zagros region of iran using the specific barrier model and the stochastic method abstract physically based ground motion prediction equations for soil and rock sites in the zagros region have been developed based on the specific barrier model sbm used within the context of the stochastic model instead of direct time domain simulation random vibration theory was used to estimate measures of peak motion in terms of the pseudospectral velocity of anelastic harmonic oscillator with 5 viscous damping to avoid the uncertainties calibration of the source model uses a database of carefully selected strong motion data without ambiguity about the site condition therefore only rock sites are selected for determining source parameters also to avoid any inconsistencies caused by magnitude conversion formulas we restricted the dataset only to events with available moment magnitudes regression analysis is performed using the random effects model that considers both interevent and intraevent variabilities to effectively deal with the problem of an unequal number of records from different earthquakes no sign of self similarity breakdown is observed between the source radius and its seismic moment the local and global stress drops derived for the zagros region 39 and 116 bars respectively are more consistent with the values obtained by other authors for an interplate regime than the values for an intraplate region however from the viewpoint of source heterogeneity as the ratio of the stress drops is an indicator of the complexity of the source and heterogeneity of slip on the fault the zagros events which have a stress drop ratio of about three are more homogeneous than other interplate events stochastic simulations are then implemented to predict peak ground motion and response spectra parameters for rock and soil site conditions online material catalog tables of earthquakes and attenuation tables