nonlinear soil site effects in probabilistic seismic hazard analysis this study presents effective probabilistic procedures for evaluating ground motion hazard at the free field surface of a nonlinear soil deposit located at a specific site ground motion at the surface or at any depth of interest within the soil formation e g at the structure foundation level is defined here in terms either of a suite of oscillator frequency dependent hazard curves for spectral acceleration or of one or more spectral acceleration uniform hazard spectra each associated s s f a with a given mean return period it is presumed that similar information is available for the rock outcrop input the effects of uncertainty in soil properties are directly included this methodology incorporates the amplification of the local soil deposit into the framework of probabilistic seismic hazard analysis psha the soil amplification is characterized by a frequency dependent amplification function af f where f is a generic oscillator frequency af f is defined as the ratio of to the spectral s s f a acceleration at the bedrock level the estimates of the statistics of the ampli s s f a fication function are obtained by a limited number of nonlinear dynamic analyses of the soil column with uncertain properties as discussed in a companion article in this issue bazzurro and cornell 2004 the hazard at the soil surface or at any desired depth is computed by convolving the site specific hazard curve at the bedrock level with the probability distribution of the amplification function the approach presented here provides more precise surface ground motion hazard estimates than those found by means of standard attenuation laws for generic soil conditions the use of generic ground motion predictive equations may in fact lead to inaccurate results especially for soft clay soil sites where considerable amplifi cation is expected at long periods and for saturated sandy sites where high intensity ground shaking may cause loss of shear strength owing to liquefaction or to cyclic mobility both such cases are considered in this article in addition to the proposed procedure two alternative easier to implement but approximate techniques for obtaining hazard estimates at the soil surface are also briefly discussed one is based on running a conventional psha with a rock attenuation relationship modified to include the soil response whereas the other consists of using a simple analytical closed form solution that appropriately mod ifies the hazard results at the rock level

why is the bay of bengal less productive during summer monsoon compared to the arabian sea 1 the bay of bengal is traditionally considered to be a less productive basin compared to the arabian sea we explore the reasons for this in the central bay during summer copious rainfall and river water freshen the upper layers of the bay by 3 7 psu during summer and sst was warmer by 1 5 2 c than in the central arabian sea this leads to a strongly stratified surface layer the weaker winds over the bay are unable to erode the strongly stratified surface layer thereby restricting the turbulent wind driven vertical mixing to a shallow depth of 20 m this inhibits introduction of nutrients from below situated close to the mixed layer bottom into the upper layers while advection of nutrients rich water into the euphotic zone makes the arabian sea highly productive this process is unlikely in the bay of bengal

incorporating results from seismic microzonation into probabilistic seismic hazard analysis an example in western liguria italy abstract this study presents a first attempt to couple two of the most important components of seismic risk mitigation strategies probabilistic seismic hazard analysis psha and seismic microzonation we show an application in the westernmost sector of the liguria region in northwestern italy an area where strong earthquakes up to about magnitude 6 5 occurred in the past producing hundreds of casualties the final goal is to produce probabilistic seismic hazard maps for peak ground acceleration and spectral acceleration that incorporate site amplification by amending existing ground motion attenuation models for rock conditions with an additional amplification term provided by microzonation studies on a municipal scale to this end a partially non ergodic approach is applied according to modern practice compared to conventional ergodic hazard assessments for rock conditions and flat topography such maps provide at a glance a finer picture of the actual hazard of the area under study highlighting those sites where the ground motion hazard is dominated by local amplification effects at these sites the expected ground motions are up to twice the values resulting from the traditional ergodic psha on rock besides hazard maps results are also presented in terms of uniform hazard spectra for a number of target sites comparison with the isoseismal maps of past earthquakes have revealed a good agreement between the spatial distribution of the assessed hazard and that of felt intensities with greater damage observed in areas presenting significant amplification effects and consequently a higher seismic hazard

weekly observations on dispersal and sink pathways of the terrigenous flux of the ganga brahmaputra in the bay of bengal during ne monsoon the analyses of 64 sequential satellite images october 1999 march 2001 of indian remote sensing satellite irs p4 ocean color monitor ocm bands around 490 555 and 670 nm for total suspended matter tsm synchronous sea truth data acquisition and salinity variations have been used to construct dispersal pathways of the surficial fluvial flux into the northern bay of bengal during the ne monsoon from the spatial extent of the plumes of tsm 160 120 km during october of 1999 and2000 off the mouth of the himalayan rivers the ganga andthe brahmaputra g b it is deduced that fluvial flux does not diminish concurrently with the termination of the southwest sw monsoon as suggestedby time series trap experiments in the northern bay during the ne monsoon the g b plumes move north to south initially off the mouth and thereafter advects sw alongshore in the form of coastal sediment plumes reducing the salinity of the coastal waters along the entire northern bay during october december we have observed a strong relation between enhanced episodic discharges of the ganga brahmaputra g b and augmented coastal turbidity during weekly events it is also observed that even during such short weekly events of very high pulse of tsm discharge by the g b system the fluvial fluxes do not advect offshore into the deeper regions of the northcentral bay but are transportedalongshore andd istributedalong the shelf our results therefore suggest that the reduced recovery of the fluxes in the sediments traps subsequent to the sw monsoon are not linearly related to the magnitude of fluvial flux of the g b but stems from the prevalent dispersal patterns r 2005 elsevier ltd all rights reserved

influences of tropical monsoon climatology on the delivery and dispersal of organic carbon over the upper gulf of thailand abstract organic carbon cycling in se asia is data sparse and poorly studied although high sediment yield and organic carbon intensity occur in the tropical region in the present study we evaluated the role of tropical monsoon pertaining to fluvial discharge sediment load coastal current and water stratification on seasonal organic carbon dynamics during four sampling campaigns in the upper gulf of thailand ugot this study demonstrates that particulate organic carbon poc is closely correlated with the river influx of suspended sediment which is generally regulated by the local rainfall higher poc is found near the large estuarine section chao phraya river chao during southwest monsoon period and the small estuarine section mae klong river mk during november 2013 when tropical cyclones impacted poc in the estuarine sections is more significantly influenced by the seasonal shift compared with the coastal sections land derived organic matter prevails in the small estuarine and coastal sections while marine derived organic matter dominates in the estuarine sections impacted by chao and mk anthropogenic inputs and dam regulation also influences the river export of organic matter during the high precipitation periods total organic carbon toc however displays less significant seasonal monsoon variations than poc further toc tends to accumulate in the sub silt fraction of sediments which mainly occurs in the small estuarine and eastern coastal sections and is more obviously influenced by marine derived factors toc in sediment of the chao and mk influenced sections however displays more seasonal variations with prevailing river input evidenced by coarser sediment and higher c n ratios moreover the almost year round water stratification across the region acts as the barrier in retaining organic carbon in the estuaries and their vicinities from dispersal into the lower portion of gulf of thailand high sedimentation rate 1 1 cm yr 1 further facilitates the organic carbon burial in the study area the delivery dispersal and burial of organic carbon are closely associated with the climate controlled precipitation and thus the tropical monsoon climatology under the global warming in particular is an important factor influencing the organic carbon in the ugot

probabilistic liquefaction induced lateral spread hazard mapping and its application to utah county utah abstract earthquake induced liquefaction may result in the lateral spread displacement of soil down gently sloping ground or towards a free face causing severe and costly damage to various facilities bridges buildings and other critical infrastructure despite the availability of analytical methods most engineers currently use empirical or semi empirical regression models to estimate liquefaction induced lateral spread displacements at specific sites however the application of these regression models for regional mapping over a large geographic areas can be difficult because of challenges associated with the adequate characterization of subsurface soil and groundwater conditions geotechnical properties regional topography and uncertainties associated with the causative seismic loading to address these challenges this paper presents a new and fully probabilistic procedure for regional hazard mapping of liquefaction induced lateral spread displacement the mapping process is demonstrated through an implementation in utah county utah to demonstrate the type of lateral spread displacement hazard maps possible maps corresponding to return periods of 1033 and 2475 years are developed for utah county utah the proposed procedure incorporates topographical data from airborne lidar surveys and geotechnical and geological data from available maps and subsurface explorations it accounts for uncertainties in the soil properties seismic loading and the empirical models for predicting lateral spread displacement using monte carlo simulations

the supply and accumulation of silica in the marine environment rivers and submarine hydrothermal emanations supply 6 1 1014g sio2 yr to the marine environment approximately two thirds of the silica supplied to the marine environment can be accounted for in continental margin and deep sea deposits siliceous deep sea sediments located beneath the antarctic polar front convergence account for over a fourth 1 6 1014g sio2 yr of the silica supplied to the oceans deep sea sediment accumulation rates beneath the polar front are highest in the south atlantic with values as large as 53cm kyr during the last 18 000 yr siliceous sediments in the bering sea sea of okhotsk and subarctic north pacific accumulate 0 6 1014g sio2 yr or 10 of the dissolved silica input to the oceans the accumulation of biogenic silica in estuarine deposits removes a maximum of 0 8 1014g sio2 yr although estuarine silica versus salinity plots indicate extensive removal of riverine silica from surface waters the removal rates must be considered as maximum values because of dissolution of siliceous material in estuarine sediments and bottom waters siliceous sediments from continental margin upwelling areas e g gulf of california walvis bay or peru chile coast have the highest biogenic silica accumulation rates in the marine environment 69 g sio2 cm2 kyr despite the rapid accumulation of biogenic silica upwelling areas account for less than 5 of the silica supplied to the marine environment because they are confined laterally to such small areas

impact of indus river discharge on productivity and preservation of organic carbon in the arabian sea over the twentieth century marine high productivity zones along the continents are of great economic importance and they account for most organic carbon burial the carbon cycle in many coastal zones is influenced by the sediments and dissolved nutrients introduced by rivers however there is little direct evidence for a regional marine response to changes in river dynamics here we present a suite of high resolution records of organic and inorganic paleoceanographic proxies which together demonstrate that past changes in indus river discharge have strongly affected productivity patterns in the coastal northeastern arabian sea anthropogenic activity including the building of dams and irrigation facilities during the past century has drastically decreased the discharge rate of the indus river between a d 1890 and 1998 the period over which this reduction occurred primary productivity off the pakistan coast seems to have decreased by more than one third over the same period the regional oxygen minimum zone weakened increasing the supply of oxygen to the sediments leaving the expected imprint on a suite of redox sensitive elements and reducing the preservation of organic matter

clay mineral accumulation rates in the arabian sea during the late quaternary abstract the regional variations in clay mineral concentrations in 39 turbidite free and undisturbed deep sea sediment cores from the arabian sea are compared with distribution patterns of clay mineral accumulation rates during the holocene and the last glaciation dust plumes from the red sea area arabia mesopotamia iran and pakistan can be traced by accumulation rates of mineral specific dust loads during the late quaternary the major proportions of aeolo marine sediments in the western arabian sea were derived from arabia during the summer season the clay mineral assemblage in these dust plumes consists of illite smectite kaolinite chlorite and palygorskite in decreasing order of abundance the distribution pattern of palygorskite in particular reveals that dust transport from southern arabia occurs mainly with northwesterly to westerly winds in the mid troposphere dust plumes from iran and pakistan which are characterized by high chlorite content are dispersed by northwesterly winds over the northwestern arabian sea dust contributions from the red sea area which are rich in smectite and characterized by the occurrence of amphiboles are transported to the gulf of aden the amount of dust related to northeast monsoon winds during the winter season appears to be negligible when compared to the proportions borne on other dust bearing winds in addition to aeolian contributions we distinguish two fluvial contributions a chlorite illite kaolinite and quartz rich assemblage from oman and pakistan into the gulf of oman and a smectite rich assemblage which is dominant off southern india originating from rivers that drain the indian subcontinent the significant difference between the holocene and glacial accumulation rates of wind transported clay minerals consist in the higher abundance of quartz illite and chlorite in the northwestern arabian sea during the last glaciation this pattern indicates intensified dust contributions by northwesterly winds from the persian gulf area which was dry during glacial times

lead concentrations in the northeast pacific evidence for global anthropogenic perturbations lead concentrations were determined by isotope dilution mass spectrometry in 34 surface and deep water samples collected in the northeast pacific between hawaii and california and off the california coast using a deep water sampler protected against fouling by contamination from the ship and hydrowire measured concentrations lie more than one order of magnitude below previously published open ocean values and they show that in most cases 90 or more of the total lead is in a dissolved form lead concentrations are about 10 fold higher in surface and thermocline waters than in deep waters values drop as low as 1 ng kg 5 pmol kg below 3500 m depth lead profiles thus appear different compared to those of most trace metals which show enrichment in deep waters compared to surface concentrations lead concentrations in surface waters increase from 5 to 15 ng kg 25 to 75 pmol kg along a transect starting from a location 200 km off the california coast and continuing towards the center of the north pacific gyre this increase is congruent with that observed for 210 pb concentrations in the same waters sampled at the same time lead is supplied to the open north pacific largely from the atmosphere at a rate of about 60 ng cm 2 yr which exceeds the prehistoric oceanic output flux of authigenic lead recorded in pelagic sediments about tenfold this excess originates from emissions from smelters and combustion of leaded gasoline overwhelming natural lead inputs that entered the ocean during prehistoric time probably largely through rivers vertical lead concentration profiles below the surface mixed layer are probably not in steady state there concentrations must be increasing in response to the increase of anthropogenic inputs because the estimated lead residence times are more than 20 years in the thermocline and about 80 years in deep waters based on an estimated 10 fold input and concentration increase since the mid eighteenth century in the surface mixed layer in the central northeast pacific it is calculated that the 10 ng kg average concentration between 100 and 900 m is 2 to 5 times larger and the 1 8 ng kg average concentration between 900 and 5000 m depth is about 2 times larger than it was in the mid eighteenth century profiles of lead concentrations in the north atlantic are expected to be shifted generally to larger values by a factor of 2 to 3 compared to those in the north pacific because of the effects of greater industrial lead contamination while lead concentration profiles in the south pacific are expected to be shifted generally to lower values compared to the north pacific by about this same factor because of the effects of lesser industrial lead contamination

influence of orographically enhanced sw monsoon flux on coastal processes along the se arabian sea 1 the arabian sea has an excess evaporation over precipitation regime the southeast arabian sea is however anomalous because it has 2800 4800 mm rainfall during the southwest monsoon swm despite a high rainfall the fluvial influence on supply of total suspended matter tsm and marine productivity is deemed insignificant and remains unevaluated we evaluated the poorly resolved influence of fluvial influx on shelf processes we documented low salinity stratification high productivity and turbidity over the entire inner shelf chlorophyll a 2 4 mg m 3 po4 3 2 5 m no3 6 8 2 1 m tsm 88 182 mg l 1 salinity near shore region 26 offshore region 33 8 34 6 p s u the deeper regions 40 m however had greatly reduced tsm and nutrient levels no3 po4 3 1 0 m tsm 24 mg l 1 and patches of high chlorophyll a upon cessation of the swm nutrient levels and tsm reduced considerable we identify two processes that contribute to the marine productivity and turbidity during the swm over the deeper regions there is a poor influence of fluvial supply and upwelling regulates productivity over the shallow inner shelf the sequestering of fluvial influx due to the prevalence of strong winds upwelling and equatorward flow is dominant the later processes induced high marine productivity and eutrophication in the near shore region and may have implications for siltation of channels reduced turbidity nutrient and chlorophyll a levels and higher salinity of the coastal waters during rest of the year imply a substantial role of fluvial fluxes on coastal processes

investigation of the ground motion variability associated with site response for sites with vs30 over 500 m s abstract understanding and reducing uncertainties in ground motion prediction are high priorities for seismic hazard analysis this article examines the variability in synthetic ground motions at rock sites caused by the variability in randomly generated velocity profiles of the geological column from 5 km depth to the surface only sites with v s 30 of 500 m s or higher are considered and linearity is assumed these synthetic estimates of the mean value of are a complicated but understandable function of magnitude period and v s 30 the distribution of modeled residual response spectral amplitudes at several oscillator periods is not lognormal but the deviations are in the central part of the distribution in which the effect on probabilistic seismic hazard analysis may not be very large adding another constraint to the velocity profile namely that the shear wave velocity of the uppermost layer should be at least 70 of v s 30 greatly reduces the uncertainty at high frequencies we tentatively identify sites with this property as nonresonant rock because it excludes sites with a strong resonance in a thin shallow layer the reduction in uncertainty that this allows might reduce or eliminate the contradiction between the u s national seismic hazard map and precarious rocks in southern california furthermore for nonresonant rock sites the residual impact of the ergodic assumption might be reduced to more tolerable levels online material tables of variability values

evaluation of probabilistic site specific seismic hazard methods and associated uncertainties with applications in the po plain northern italy site specific ground motion hazard as assessed by a probabilistic seismic hazard analysis one step approach that handles a single site sigma and its uncertainties and uses a simple logic tree is compared with a two step approach that includes bedrock motion evaluation and wave propagation through a local soil profile with consideration of the main epistemic uncertainties the one step analysis relies on accelerometer data from the po plain a sedimentary basin in northern italy where an earthquake sequence with two m w 6 0 events was extensively recorded in 2012 uniform hazard spectra uhs on soil and exposed bedrock are evaluated at three deep soil accelerometer sites mrn nvl and t0821 using residual measures available from other studies by which uncertainties in site terms s 2 s and single site sigma ss s are estimated despite similarity in geologic conditions at least one out of three sites in the one step analysis displays substantial differences in mean level t0821 or in the 84 16 percentile spread nvl depending on differences in site terms and single site sigma possibly caused by source to site propagation effects the two step approach was applied to the remaining site mrn using carefully selected and broadband matched acceleration signals and linear equivalent linear and nonlinear approaches as excitation in propagation analyses we found that assumptions on soil degradation curves dominate the variability of results the linear approach provided the best results based on 1 the similarity of the one step nonergodic uhs with the two step result based on the linear approach 2 the comparison with observed records at mrn during the 2012 sequence mainshocks showing peak ground acceleration and short period spectral levels well beyond those predicted by different nonlinear assumptions and 3 similar evidence from a set of 21 stations at deep soil sites of the japanese kik net

long period amplification in deep alluvial basins and consequences for site specific probabilistic seismic hazard analysis an example from the po plain northern italy this study deals with the impact of deep soil discontinuities on ground motion amplification in the po alluvial basin northern italy and consequently on long period probabilistic seismic hazard analysis estimates the focus is on castelleone where a seismic station of the italian national seismic network has been deployed since 2009 to define a detailed shear wave velocity v s profile extensive active and passive geophysical surveys were carried out the active measurements included seismic profiles examined through standard refraction techniques and multichannel analysis of surface waves the passive methods included ambient vibration measurements in both single and array configurations in particular three microtremor arrays with increasing apertures were performed to capture the experimental dispersion curve down to 0 2 hz the horizontal to vertical spectral ratio hvsr showed two main peaks at 0 17 and 0 70 hz a joint inversion of the experimental phase velocity dispersion and hvsr curves was performed to obtain the v s profile the data show two main discontinuities at 160 and 1350 m in depth according to the italian and european seismic codes the shallow v s discontinuity can be ascribed to the seismic bedrock i e v s 800 m s whereas the deeper one is observed at the transition between pliocene quaternary deposits and miocene marls preliminary site specific seismic hazard analysis in terms of displacement response spectra for periods up to 10 s shows that neglecting the effects of the deeper discontinuity implies underestimation in hazard estimates of up to about 49 for mean return period mrp of 475 years and about 57 for mrp of 2475 years with possible consequences regarding the design of very tall buildings and large bridges

geochemical cycles of elements and human perturbation abstract the pollution inputs of various elements are omnipresent in aerosols snows rivers and the ocean of the northern hemisphere the mid ocean ridges are not important sinks or sources for most of the elements the settling of fecal pellets is the predominant transport mechanism of most elements except mn co and ni from the surface to deep oceans dissolved mn co and ni are directly incorporated into pelagic clays at the sediment water interface

atmospheric summer circulation and coastal upwelling in the arabian sea during the holocene and the last glaciation accumulation rates of biogenic and lithogenic components were studied in 39 turbidite free well dated sediment cores from the northern indian ocean to define the proportions of fluvial and eolian input and to reconstruct quaternary patterns of coastal upwelling the majority of dust deposited in the western arabian sea during the holocene about 100 106 t yr 1 is advected from arabia by northwesterly winds which overlie the low level southwest monsoon the glacial increase in dust flux to 160 106 t yr 1 culminated in the northern arabian sea most probably due to i entrainment of dust rich in chlorite dolomite and lithogenic carbonate in the then dry persian gulf and ii a southward shift of the mean position of the southwest monsoon during glacial summer this shift is recorded in reduced accumulation rates of biogenic opal and increased rates of marine carbonate off somalia and oman both the terrigenous and biogenic sediment records show that the northwesterly winds and the southwest monsoon persisted over the last 27 000 yr as well as the asian continental summer heat low however the glacial seasonal time span of the southwest monsoon season was much reduced most likely because of a delay in the seasonal onset of the southwest monsoon

probabilistic seismic hazard analysis considering nonlinear site effect a modified method is proposed for the probabilistic seismic hazard analysis considering nonlinear site effect a case study is presented to show the hazard curves that consider the nonlinearity of the soil layers at gilroy 2 source parameters and an earthquake occurrence model are assigned to the caleveras fault which is assumed the dominant seismic source to the site a relationship between ground surface and bedrock accelerations at the site is established by recordings from three earthquake events using the program nonli3 which calculates the nonlinear responses of the soil layers to strong motions various values of standard errors of the estimated surface pga given the bedrock motions are assumed to perform a sensitivity analysis an alternative nonlinear relation is included in the case study in addition to the nonlinear models a linear response model is also performed using the same soil profile at gilroy 2 the results demonstrate that the hazard curves are sensitive to the standard error of the estimated surface pga values at the site the hazard curve may be severely distorted if the soil condition of a nonlinear site is treated inadequately the alternative nonlinear model obtained empirically from regression analysis and the linear response model are both unsuitable for the hazard assessment considering nonlinear site effect

intrusion of the bay of bengal water into the arabian sea during winter monsoon and associated chemical and biological response this work was supported by the department of ocean development under the program marine research living resources mr lr jayu narvekar acknowledges the financial support from csir

a 5000 yr record of climate change in varved sediments from the oxygen minimum zone off pakistan northeastern arabian sea the upper holocene marine section from a kasten core taken from the oxygen minimum zone off karachi pakistan at water depth 700 m contains continuously laminated sediments with a sedimentation rate of 1 2 mm yr and a unique record of monsoonal climatic variability covering the past 5000 years our chronostratigraphy is based on varve counts verified by conventional and ams 14 c dating individual hemipelagic varve couplets are about 0 8 1 5 mm thick with light colored terrigenous laminae a deposited mainly during the winter monsoon alternating with dark colored laminae b rich in marine organic matter coccoliths and fish debris that reflect deposition during the high productivity season of the late summer monsoon august october precipitation and river runoff appear to control varve thickness and turbidite frequency we infer that precipitation decreased in the river watershed indicated by thinning varves after 3500 4000 yr b p this is about the time of increasing aridification in the near east and middle east as documented by decreasing nile river runoff data and lake level lowstands between turkey and northwestern india this precipitation pattern continued until today with precipitation minima about 2200 1900 yr b p 1000 yr b p and in the late middle ages 700 400 yr b p and precipitation maxima in the intervening periods as documented by spectral analysis the thickness of varve couplets responds to the average length of a 250 yr cycle a 125 yr cycle the gleissberg cycle of solar activity 95 yr and a 56 yr cycle of unknown origin higher frequency cycles are also present at 45 39 29 31 and 14 yr the sedimentary gray value also shows strong variability in the 55 yr band plus a 31 yr cycle because high frequency cyclicity in the enso band ca 3 5 and 5 yr is only weakly expressed our data do not support a straightforward interaction of the pacific enso with the monsoon driven climate system of the arabian sea

a brief discussion on the mean oceanic residence time of elements abstract the mean oceanic residence times of elements obtained from deposition rates in deep sea sediments are more representative than those obtained from river input rates the average concentration data of dissolved s au ag se as hg sb zn sn cu and pb in rivers contain large pollution and or contamination components

on the role of stiff soil deposits on seismic ground shaking in western liguria italy evidences from past earthquakes and site response abstract in this work we analyze the macroseismic fields of the main historical earthquakes occurred in western liguria northwestern italy in order to identify possible relations between the isoseismal patterns and the local geological setting anomalies in the spatial distribution of macroseismic intensities are often attributed to site effects we observed that in the region of study such anomalies are mainly located in areas characterized by outcropping pliocene soil deposits mainly made up of stiff silty and marly clays to investigate the influence of such deposits on ground response both horizontal to vertical spectral ratio measurements and numerical site response analyses were carried out for all sites analyzed the spectral ratio curves show marked amplification peaks between 2 and 5 hz following such empirical evidence equivalent linear ground response analyses were performed in order to examine the relation between the measured resonance frequencies and the response of a set of soil columns presenting pliocene marly clayey deposits at their top to this end a database of geotechnical and geophysical properties including 50 reference soil profiles was compiled this database was used to define alternative numerical models considering three different ranges of thickness of the pliocene marly clayey deposits between 5 and 35 m 30 and 65 m 60 and 105 m results show marked amplification effects in the ranges 1 3 hz 2 5 hz and 3 10 hz depending on the thickness of the investigated soil deposits these frequency ranges are in agreement with those observed from the experimental measurements which are therefore proved adequately representative of the resonance frequencies of the pliocene marly clayey deposits therefore based on our findings such deposits can be considered an essential factor in producing the anomalies observed in the isoseismal patterns of the macroseismic fields of the historical earthquakes occurred in western liguria

evaluation of the influence of monsoon climatology on dispersal and sequestration of continental flux over the southeastern arabian sea abstract associated with the coupled land ocean heating cooling seasonal reversal of monsoon winds regulates hydrography precipitation upwelling fluvial influx and a host of biogeochemical processes we evaluate the role of the monsoon winds fluvial discharge and currents on continental flux dynamics from advection magnitude of clays over an anomalous high precipitation regime of the southeastern arabian sea coupled with the intense rains and a high fluvial discharge we archived an elevated content of detrital clays 41 mg l 1 during the southwest monsoon over the 40 m however had much reduced detrital clays

anomalous inland influx of the river indus gulf of kachchh india the gulf of kachchh is a funnel shaped macrotidal water body located in the arid region of northwestern india with 50 cm annual rainfall and insignificant fluvial input the gulf waters however have high suspended matter time series measurements of total suspended matter tsm and synchronous validated hydrodynamic modeling have been used to decipher the dispersal pathways and the sources of the high turbidity contrary to the prevalent offshore reducing trend for most of the indian coast the gulf is anomalous for having an enhanced turbidity at the mouth with lower concentrations in the inland areas the hydrography of the gulf is dominated by strong alongshore currents at the mouth which move in out during flood ebb and undergo cyclic dynamic changes with tidal phases the flood tidal currents amplify inland with propagating tides pulling in the offshore waters and acting as a feeder of high saline turbid offshore waters into the gulf most of which are trapped inland due to time lag of ebb and flood between the outer and the inner gulf based upon the distribution maps of tsm and clays in the water column it is deduced that a large segment of the gulf is nourished by contributions from the indus river

ocean currents and sea surface heights estimated across the west florida shelf abstract the across shelf structures of the ocean circulation and the associated sea surface height ssh variability are examined on the west florida shelf wfs for the 3 yr interval from september 1998 to december 2001 five sets of characteristic circulation patterns are extracted from 2 day low pass filtered data using the self organizing map extreme upwelling and downwelling structures with strong currents asymmetric upwelling and downwelling structures with moderate currents and a set of transitional structures with weak currents the temporal variations of these structures are coherent with the local winds on synoptic weather time scales on seasonal time scales they are related to both the local winds and the water density variations the circulation is predominantly upwelling during autumn to spring months october april and downwelling during summer months june september coastal sea level fluctuations are related to both the dynamical responses of the inner shelf circulation to meteorol

seismic reliability of axially loaded vertical piles the reliability of single vertical pile foundations subjected to seismic loads is assessed and compared with the minimum acceptable reliability level for static load conditions mandated by the cana

indian summer monsoon and winter hydrographic variations over past millennia resolved by clay sedimentation 1 reconstruction of century scale indian monsoon and winter hydrography is made from an ams dated core located in the unique region of the southeast arabian sea which lies in the pathways of the low salinity bay of bengal waters advecting during winter northeast monsoon nem based upon clay mineral analyses in seawaters we identify chlorite and kaolinite as specific clays supplied by the bay of bengal waters and local fluvial flux by the southwest monsoon swm precipitation from the peninsular india respectively along the southwest continental margin of india an evaluation of clay flux and 18o in g ruber portrays century scale weaker swm precipitation events during 450 650 yr 1000 yr and 1800 2200 cal yr bp kaolinite wt and flux were found to be low during all these events though chlorite had a persistent or enhanced flux from the enhanced flux of chlorite and reduced kaolinite chlorite ratio during weaker phases of swm we deduce a stronger nem winter hydrography implying an inverse coupling between the summer and the winter monsoon

the impact of the spatial uniform distribution of seismicity on probabilistic seismic hazard estimation the first step in the estimation of probabilistic seismic hazard in a region commonly consists of the definition and characterization of the relevant seismic sources because in low seismicity regions seismicity is often rather diffuse and faults are difficult to identify large areal source zones are mostly used the corresponding hypothesis is that seismicity is uniformly distributed inside each areal seismic source zone in this study the impact of this hypothesis on the probabilistic hazard estimation is quantified through the generation of synthetic spatial seismicity distributions fractal seismicity distributions are generated inside a given source zone and probabilistic hazard is computed for a set of sites located inside this zone in our study the impact of the spatial seismicity distribution is defined as the deviation from the hazard value obtained for a spatially uniform seismicity distribution from the generation of a large number of synthetic distributions the correlation between the fractal dimension d and the impact is derived the results show that the assumption of spatially uniform seismicity tends to bias the hazard to higher values the correlation can be used to determine the systematic biases and uncertainties for hazard estimations in real cases where the fractal dimension has been determined we apply the technique in germany cologne area and in france alps