estimation of seismic hazard parameters for the himalayas and its vicinity from complete data files the maximum likelihood estimation of earthquake hazard parameters has been made in the himalayas and its surrounding areas on the basis of a procedure which utilizes data containing complete files of the most recent earthquakes the entire earthquake catalogue used covers the period from 1900 1990 the maximum regional magnitude m max the activity rate of the seismic event the mean return period r of earthquakes with a certain lower magnitude m max m along with their probability of occurrence as well as the parameter b of of gutenberg richter magnitude frequency relationship have been determined for six different seismic zones of the himalayas and its vicinity it is shown that in general the hazard is higher in the zone nei and ban than the other four zones the high difference of the b parameter and the hazard level from zone to zone reflect the high seismotectonic complexity and crustal heterogeneity

the viscosity of fine grained sediments a comparison of low to medium activity and high activity clays abstract viscosity is generally recognized as an indicator of landslide mobilization viscous behavior at relatively low high shear rates is an important predictor of the motion of slow fast moving landslides the viscosity in a modified bingham model at low and high shear rates was examined the viscous characteristics are primarily dependent on the physico chemical properties of the materials in question e g grain size mineralogy salinity in this context the viscous characteristics of low to medium activity and high activity clays bentonite with different salinities were compared empirical relationships exist between the liquidity index and the plastic viscosity regardless of the mineralogical composition this study also demonstrated a positive relationship between the liquidity index and the viscosity in a modified bingham model with n 1 the results showed that low to medium activity and high activity clays fall into a similar range for fine grained sediments mixed with salt water 30 g l however an effect of salinity was evident when using high activity clays mixed with fresh water modified bingham model is a useful and powerful tool for describing pre and post yield viscosity in engineering practice by correlating the geotechnical and rheological properties of fine grained sediments index properties can help to estimate the appropriate values for the rheological parameters of these soils

flow behaviour and runout modelling of a complex debris flow in a clay shale basin identification of debris flow hazard areas necessitates the knowledge of the flow thickness and the runout distance both have been investigated using a numerical runout model on the faucon stream south french alps representative of clay shale basins results of various rheological tests and numerical experiments are presented and discussed the calibration of the model was undertaken using the results of both geomorphological surveys and sedimentological analyses rheological tests using either a parallel plate rheometer a coaxial rheometer slump tests and an inclined plane were carried out on several samples results have shown that the flow behaviour could be described by an herschel bulkley constitutive equation the rheological responses of several natural suspensions collected from surficial deposits sandstones moraines weathered black marls were also investigated in order to model the runout of the flow the model bing was used the model describes well the influence of each type of sediment on the behaviour runout distance deposit thickness of the flow although the velocities were significantly overestimated different risk scenarios are tested and discussed copyright 2005 john wiley sons ltd

kinematics of active deformation in the sulaiman lobe and range pakistan the western margin of the indian plate is highly oblique to the direction of convergence between india and asia and represents an excellent example of large scale oblique continent continent collision determining the strain field in western pakistan and how it relates to the plate motion and plate margin geometry affords an exceptional opportunity for understanding oblique margin processes in general through the inversion of regional and teleseismic body waves we have determined the source parameters of 10 moderate sized earthquakes that occurred between 1964 and 1985 in and around the sulaiman range pakistan the earthquakes are dominantly thrust events with slip vectors that are approximately perpendicular to the lobate sulaiman mountain front slip vector orientations rotate 60 70 from a n s to a wnw ese direction of compression consistent with the geometries of the complex festoon shaped mountain belts of this margin we have estimated the spatial variation of the horizontal strain rate and velocity fields within sulaiman using vertically averaged models that accommodate plate motion constraints within a deforming layer the most important factors determining the style of strain rotation in the sulaiman lobe and range are the presence of pure strike slip motion along the chaman fault and the relatively rigid and undeformed katawaz basin that is therefore allowed to translate obliquely relative to india this same conclusion is obtained using either a three dimensional frictional analogue model with significant basal tractions or a thin sheet viscous numerical model without basal tractions thrusting in a predominantly nw se direction in the sulaiman range accommodates 5 14 mm yr of n s motion between india eurasia and 3 6 mm yr of e w shortening seismic moment release this century within the india eurasia plate boundary zone west of the western himalayan syntaxis constitutes roughly 40 of the expected total seismic moment release for this time period particularly significant moment rate deficits exist within the sulaiman range and along the chaman fault

numerical analysis of the mobility of the palos verdes debris avalanche california and its implication for the generation of tsunamis abstract analysis of morphology failure and post failure stages of the palos verdes debris avalanche reveals that it may have triggered a significant tsunami wave our analysis of the failure itself indicates that the slope is stable under aseismic conditions but that a major earthquake with a magnitude around 7 could have triggered the slide a post failure analysis considering the debris avalanche as a bi linear flow shows that peak velocities of up to 45 m s could have been reached and that the initial movement involved a mass of rock less than 10 km wide 1 km long and about 50 80 m thick initial wave height estimates vary from 10 to 50 m tsunami waves propagating to the local shoreline would be significantly smaller such a range demonstrates our lack of proper knowledge of the transition from failure to post failure behavior related to mass movements further investigations and analyses of terrestrial and submarine evidence are required for a proper hazard assessment related to tsunami generation in the los angeles area

significance of coarse clasts in viscous debris flows abstract debris flows are flowing mixture of water and sediments from clay to boulder sized particles the sediments control both occurrence and characteristics of debris flows however the relevant literature has concentrated mainly on fine debris considering their large fractions in debris flows the significance of coarse clasts 0 005 mm is investigated by comparing the crude debris cd the fractions of aggregation of data collected in 39 tested debris water mixtures leads us to conclude that the coarse clasts can greatly affect the slurrying susceptibility of debris masses and bulk behavior of slurries the debris flow indices id from the cd to rd slurries with maximum grain sizes of 10 and 5 mm decrease by 29 and 17 respectively the cd slurries possess higher yield strength and viscosity than their rd counterparts with the same solid volumetric concentrations cvs the areas inundated by 10 cd slurries with maximum grain sizes of 10 and 5 mm are approximately 17 39 of those of their rd counterparts the excess pore pressures in the rd slurries dissipate more quickly than those in the cd slurries the shape and surface texture of coarse clasts regulate slurrying of debris masses as well as influence their liquefaction potential which in turn has an impact on the mobility and persistence of subsequent slurries the platy flaky debris producing mountain catchments generally experience lower magnitude higher frequency lower cv debris flows of relatively less destructive power and the debris flows dominated by equidimensional clasts are often more powerful and hazardous despite their potentially lower frequency

shear resistance of remoulded soils by viscometric and fall cone methods a comparison for the canadian sensitive marine clays the coaxial viscometer can be used to extend the measurement of the shear resistance of a soil below the range of applicability of the fall cone and other standard geotechnical methods the factors affecting the relationship between yield stress determined by the viscometer and remoulded shear strength determined by the fall cone are such that the correlation must be separately determined for each soil material approaches to determining this correlation for quick clays and other soils are proposed key words sensitive clays yield stress shear strength rheology

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

1d numerical model of muddy subaqueous and subaerial debris flows a 1d numerical model of the downslope flow and deposition of muddy subaerial and subaqueous debris flows is presented the model incorporates the herschel bulkley and bilinear rheologies of viscoplastic fluid the more familiar bingham model is integrated into the herschel bulkley rheological model the conservation equations of mass and momentum of single phase laminar debris flow are layer integrated using the slender flow approximation they are then expressed in a lagrangian framework and solved numerically using an explicit finite difference scheme starting from a given initial shape a debris flow is allowed to collapse and propagate over a specified topography comparison between the model predictions and laboratory experiments shows reasonable agreement the model is used to study the effect of the ambient fluid density initial shape of the failed mass and rheological model on the simulated propagation of the front and runout characteristics of muddy debris flows it is found that initial failure shape influences the front velocity but has little bearing on the final deposit shape in the bingham model the excess of shear stress above the yield strength is proportional to the strain rate to the first power this exponent is free to vary in the herschel bulkley model when it is set at a value lower than unity the resulting final deposits are thicker and shorter than in the case of the bingham rheology the final deposit resulting from the bilinear model is longer and thinner than that from the bingham model due to the fact that the debris flow is allowed to act as a newtonian fluid at low shear rate in the bilinear model

flocculation and sedimentation on the po river delta with the goal of improving understanding of the effect of flocculation on the formation of fine grained deposits on continental shelves hydrographic profiling in situ imaging of suspended matter and collection of surficial sediment samples were conducted at the po river delta in june 2001 these data show that during medium flow conditions 1920 m3 s sedimentation occurs rapidly immediately offshore of the main distributary po della pila rapid sedimentation is promoted by large rapidly sinking flocs forming in the river well upstream of the mouth the delivery of fine sediment to the seabed at the mouth of the po is sufficient to overwhelm the erosive effects of waves and currents leading to accumulation of mud in water depths as shallow as 4 m on cross shelf transects 2 km north and south of the mouth however suspended sediment supply from the river is reduced to the point that mud accumulates only seaward of the 8 m isobath along the central transect suspended sediment concentration decreases rapidly seaward of the 6 m isobath where the emergence of a more organic rich population of flocs along a mid water density interface is suggested energetic activity along the 15 m isobath likely promotes resuspension with the potential for removal of material from the delta further investigation of floc properties namely the relationship of floc size to settling velocity is necessary to establish the degree to which the suspension is flocculated during transport and deposition

a seismic hazard map of india and adjacent areas abstract we have produced a probabilistic seismic hazard map showing peak ground accelerations in rock for india and neighboring areas having a 10 probability of being exceeded in 50 years seismogenic zones were identified on the basis of historical seismicity seismotectonics and geology of the region procedures for reducing the incompleteness of earthquake catalogs were followed before estimating recurrence parameters an eastern united states acceleration attenuation relationship was employed after it was found that intensity attenuation for the indian region and the eastern united states was similar the largest probabilistic accelerations are obtained in the seismotectonic belts of kirthar hindukush himalaya arakan yoma and the shillong massif where values of over 70 g have been calculated

characterization and rheology of krishna godavari basin sediments abstract the krishna godavari offshore basin to the east of india is a proven reserve rich in natural gas hydrate the impact of sediment characteristics on the hydrate formation has already been well established in open literature in the present study we have attempted to investigate the mineralogy of sediments collected from kg basin by elemental analysis energy dispersive spectroscopy and x ray diffraction various physicochemical characteristics of the clayey sediments such as tds salinity ph conductivity and resistivity were analysed at various concentrations and compared together also this paper highlights the rheological behavior of the sediment samples with concentrations of 20 35 and 50 wt at different experimental temperatures 278 15 k 283 15 k and 288 15 k viscosity measurements were performed for a wide range of shear rates for all concentrations and comparative studies have been conducted on their exhibited behavior the viscosity of sediment sample were found to be varying from 76 3 to 0 003 pa s depending on the sediment concentration temperature and shear rate in addition viscoelastic measurements were carried out at various angular frequencies for all the sediment samples the work aims to characterise the sediments of kg basin and analyse the rheological behavior of sediment solution which has not yet been reported in open literature this will provide vital information for possible methane recovery from kg basin hydrate reservoir by manipulating the host sediment behavior

probabilistic appraisal of earthquake hazard parameters deduced from a bayesian approach in the northwest frontier of the himalayas a straightforward bayesian statistic is applied in five broad seismogenic source zones of the northwest frontier of the himalayas to estimate the earthquake hazard parameters maximum regional magnitude mmax value of g r relationship and seismic activity rate or intensity for this purpose a reliable earthquake catalogue which is homogeneous for mw 5 0 and complete during the period 1900 to 2010 is compiled the hindukush pamir himalaya zone has been further divided into two seismic zones of shallow h 70 km and intermediate depth h 70 km according to the variation of seismicity with depth in the subduction zone the estimated earthquake hazard parameters by bayesian approach are more stable and reliable with low standard deviations than other approaches but the technique is more time consuming in this study quantiles of functions of distributions of true and apparent magnitudes for future time intervals of 5 10 20 50 and 100 years are calculated with confidence limits for probability levels of 50 70 and 90 in all seismogenic source zones the zones of estimated mmax greater than 8 0 are related to the sulaiman kirthar ranges hindukush pamir himalaya and himalayan frontal thrusts belt suggesting more seismically hazardous regions in the examined area the lowest value of mmax 6 44 has been calculated in northern pakistan and hazara syntaxis zone which have estimated lowest activity rate 0 0023 events day as compared to other zones the himalayan frontal thrusts belt exhibits higher earthquake magnitude 8 01 in next 100 years with 90 probability level as compared to other zones which reveals that this zone is more vulnerable to occurrence of a great earthquake the obtained results in this study are directly useful for the probabilistic seismic hazard assessment in the examined region of himalaya

rheological properties of fine grained sediment the roles of texture and mineralogy rheological properties of fine grained sediments depending on index properties and salinity were examined to characterize flow behaviors as a function of soil type groups were made for convenienc

evaluation of the viscosity of tropical soils for debris flow analysis a new approach to analyse the debris flow type of landslides it is necessary to know the viscosity of the fast moving soil mass such rheological parameters are important in the evaluation of characteristics of propagation of the movement downhill this paper presents a proposal for the assessment of soil viscosity based on a modified set up of the well known concrete slump test through the definition of shearing rates in the slump tests soil viscosity was determined on a plate plate rheometer four natural soils from rio de janeiro brazil with differing grain size distribution and plasticity were used in the investigation the results obtained are compared with experimental data from the literature and show that care must be taken in defining viscosities based only on data related to grain size correlations between soil moisture and shearing rates defined in the modified slump tests and viscosity defined in the rheometer tests were obtained as a result a fairly good relationship between shearing rate and v

thixotropic behavior during shear of a fine grained mud from eastern canada the quantitative determination of the hysteresis loop area developed during viscometer tests on shear rate shear stress reverse paths has been used to describe the thixotropic behavior of a clayey mud under flow conditions tests were conducted for liquidity indexes between 1 8 and 4 0 and for six pore water salinities ranging from 0 1 to 30 g l admitting that a low hysteresis loop area denotes a well developed thixotropic behavior for a given liquidity index the thixotropy of the slurry is likely to be more strongly marked for salinities greater than the flocculation threshold at a constant salinity the results also indicate the existence of a simple linear relationship between the hysteresis loop area and the yield stress and the viscosity of the slurry the restrictions of this approach and the possible implications of a strengthening softening process on mudflow kinematics are also discussed

probabilistic assessment of earthquake hazard in israel abstract the earthquake hazard in israel is assessed on the basis of the cornell mcguire probabilistic approach using the available set of instrumental and historical regional earthquake data a horizontal peak ground acceleration probability map is presented based on a proposed seismicity model earthquake source zonation and the application of the joyner boore attenuation relationship the present results differ from those previously obtained owing to the technique used the incorporation of a greater amount of instrumental data and the use of a more appropriate attenuation relationship for the first time regional earthquake hazard analysis incorporates the active carmel and farah faults this alters the risk estimate and is important considering their proximity to densely populated and industrialized areas an approximate sensitivity analysis is carried out for main model input parameters with inherent uncertainties

an integrated procedure to evaluate rheological parameters to model debris flows abstract in the present paper the problem of modeling the propagation of debris flow using suitable rheological parameters is considered a new procedure is proposed based on field observations laboratory investigations and numerical analysis the back analysis of a debris flow event that occurred in the campania region southern italy was used to investigate the reliability of the assumed rheological parameters the well known bingham constitutive equation was chosen to model the behavior of the equivalent flow mixture numerical analysis was conducted using dan w a code based on a single phase depth averaged continuum mechanics approach the results show that extrapolating model parameters only from laboratory experiments may lead to inaccurate predictions instead when the rheological parameters are assumed according to stress field observations and experimental data the model satisfactorily replicates the case studies such conclusion suggests that the calibration of model parameters using an integrated approach may be applicable for field scale debris flow simulations and can yield useful information about the dynamics of flows to be investigated the accuracy of this approach was demonstrated by the numerical prediction of other fifty events that occurred in the same area

rheology of concentrated granular suspensions and possible implications for debris flow modeling 1 granular suspensions are of major relevance for many geophysical flows we investigated the rheological behavior of three samples taken from a debris flow deposit at varying solid concentration from 38 0 to 54 2 by volume and grain size distribution experiments were performed first on the fraction finer than 0 075 mm and then on suspensions with fine sand up to 0 425 mm in size and percentages varying from 10 to 50 a vane apparatus connected to a rotational rheometer was used and experiments showed a reproducibility within 12 results were processed by the tikhonov regularization method in order to convert the shear stress versus rotation velocity curves to shear stress versus shear rate flow curves at shear rates lower than 3 5 s 1 shear stress is rate independent at higher shear rates the shear stress increases depending on the maximum grain particles included within the suspension we used the herschel bulkley and bingham models to describe the monotonous increase of the flow curves varying the grain size distribution of the samples the power and consistency indexes range within 0 75 1 35 and 0 44 40 8 pa s n where n is the exponent of the viscosity coefficient varies from 1 0 to 47 2 pa s and the shear stress varies from 28 to 1959 pa for materials mainly composed of silt and clay with a variable sand content 1 an increase in the particle size changes the rheological behavior from shear thinning to shear thickening and 2 the percentage of sand affects both the frictional character of the flow and the magnitude of the rheological parameters

shear wave velocity drop prior to clayey mass movement in laboratory flume experiments abstract clay slopes are susceptible to suddenly liquefy into rapidly accelerating landslides thereby threatening people and facilities in mountainous areas because the shear wave velocity v s characterizes the medium stiffness this parameter can potentially be used to investigate the rheological behavior of clay materials before and during the solid to fluid transition associated to such landslide failures previous rheometrical studies performed on clay samples coming from trieves landslides french alps have established that this material behaves as a yield stress fluid with a marked viscosity bifurcation when the applied stress reaches a critical level the viscosity decreases abruptly along with v s which tends to zero in the fully fluidized material here we monitor the rayleigh wave velocity v r variations in a saturated clay layer placed in a flume and progressively brought to failure by tilting the device experiments performed on clay samples with different water contents show a significant relative drop in v r values and hence in v s before the onset of the mass movement additional rheometrical analyses point out that this precursory drop in v s is presumably due to a complex transient rheological response of the clay these new results confirm that v s variations constitute a good indicator for monitoring clay slope stability

applicability of power law for describing the rheology of soils of different origins and characteristics the rate dependent rheological behaviour of soils of different origins and characteristics was studied and the applicability of the power law model was examined the studied soils were divided into

subseafloor stratigraphic profiling and soil classification from piezocone tests a case study in the gulf of lion nw mediterranean sea we show the results provided by piezocone tests in determining the stratigraphic profile and the soil classification of two drilling sites in the outer shelf and the upper slope of the gulf of lion prgl2 and prgl1 respectively correlations with grain size data indicate that sleeve friction can be used for profiling fine grained sediments site prgl1 whereas cone tip resistance is the most adequate for sequences made of alternations of coarse and fine grained intervals site prgl2 normalized cone resistance and friction ratio proved to be also appropriate for soil stratigraphy as it depicts trends in the coarse fraction of the tested soil silts and clays present in similar proportions at site prgl1 responded to piezocone testing as pure clays usually do consequently classical soil classification methods resulted in erroneous interpretation of these sediments as clays whereas classification of the heterogeneous deposits at prgl2 was consistent with the grain size when tied to a high resolution seismic reflection profile the stratigraphy interpreted from the piezocone profile matches with the main seismic sequences and discontinuities defined from seismic stratigraphy analysis graded bedding also matches with cone tip resistance and sleeve friction data