the present day formation of apatite in mexican continental margin sediments abstract results of pore water and sediment analyses from the western mexican continental margin strongly suggest the present day formation of apatite the interstitial water phosphate and fluoride profiles indicate chemical removal at a depth which corresponds to a large maximum in the phosphorus content of the sediments apatite is identified within this maximum via x ray diffraction but is elsewhere undetectable in the core radioisotopic thorium uranium and radium data support the conclusion that this deposit is modern the present day depositional environment is consistent with those reported by other workers for phosphorite formation with the exception that pore water magnesium is not depleted below its seawater value

weathering and morphogenesis in a mediterranean climate calabria italy abstract deeply weathered plutonic rocks occur widely in the sila massif calabria southern italy three representative weathering profiles developed on the hilltops indicate that sand represents more than 50 by weight throughout most of the weathering profile and silt and clay size fractions are also well represented filling the interstices among corestones both sand and finer fractions of grus and soil horizons are thought to be derived from a combination of granular disintegration and chemical decomposition developed on relatively flat terrains of the sila massif these slopes are now experiencing transport limited morphodynamics under a montane modified mediterranean climate the depth of the weathered layers that have suffered little erosional truncation typically exceed 15 m and may reach 50 60 m or more major isolated or grouped exfoliation boulders are the most common minor landform feature developed on the sila massif granite boulders have developed as a result of spheroidal weathering and by removal of the sandy textured granite the schmidt hammer sh test on boulders and corestones suggests three distinctive degree of weathering from moderately to completely weathered rock and that biotite content is the major controlling factor of the granite mechanical behaviour understanding of the dynamics of this weathering system is crucial to the interpretation of the complex suite of variables that control landscape evolution of granitoid terrains

microbial processes in the negev phosphorites southern israel microscopic and sem observations indicate that cyanobacterial activity was important during the formation of the campanian negev phosphorites one aspect of such activity is the development of phosphorites through the binding of phosphate particles these sediments often demonstrate a conspicuous smooth cryptalgal lamination the algal binder was fossilized as intertwined phosphatic sheaths that coat and seal off the phosphate grains different types of sheaths representing the remnants of an algal community were found thick apatite overgrowth commonly deforms the microbial fossils converting them into barely recognizable forms fabrication of phosphate particles is another aspect of the microbial activity phosphate algal coated grains are a common constituent of the negev phosphorites the algal coating consists of stacked phosphatic tubes and colonies of coccoid unicells with an apatite infilling fragmented phosphatic sheath bundles form another type of phosphate particle produced by algae obliteration of algal structures is common resulting in undifferentiated groundmasses of cryptocrystalline apatite the extremely close connection between microbial structures and phosphatization processes suggests cyanobacterial participation in phosphorus enrichment

far field simulation of tsunami propagation in the pacific ocean impact on the marquesas islands french polynesia the islands in the marquesas archipelago are most exposed to far field tsunamis in french polynesia four recent earthquakes located at the pacific rim kurile 1994 chile 1995 mexico 1995 and peru 1996 earthquakes generated trans pacific tsunamis and caused contrasting inundations in several inhabited marquesian bays the aim of this study is to better understand the amplification phenomena observed in the marquesas islands and to improve the risk assessment we present here numerical simulations of these four tsunamis by means of a finite difference model solving the equations of tsunami propagation at different scales the water heights computed in the bays are in excellent agreement with the available observations and thus validate our numerical method these numerical results allow us to determine 1 which propagation azimuths are dangerous for the whole marquesas archipelago and 2 the behavior of each studied bay amplitude frequency in response to tsunami waves we observe that the seismogenic subduction zone along south america is likely to define one of the most dangerous tsunami generation areas for the marquesas archipelago owing to the source geometries and to the trapping of the tsunami energy by bathymetric features in the southern pacific ocean fracture zones seamount chains

weibull vs lognormal distributions for fluvial gravels abstract krumbein and tisdel 1940 suggested that the particle size distribution of a weathered source rock tends to follow the rosin distribution whereas with distance downstream fluvially transported sediment tends to follow the lognormal distribution this issue can be illuminated somewhat by recognizing that the rosin distribution is the same as the well studied weibull distribution however it can be difficult to distinguish the lognormal rosin weibull and even gamma distributions in particle size distribution curves brennan and durrett 1987 suggest that differences in splitting rates can give rise to the lognormal vs weibull distributions but the geological implications of these concepts and the integration of the effects of sorting by fluvial transport remain to be addressed

accumulation and biological mixing of peru margin sediments abstract rates of sediment accumulation and biological particle mixing in eight cores from the peru shelf have been estimated by application of uranium series disequilibrium techniques and radiocarbon dating activities of 210pb 226ra 234th and 238u have been determined in closely spaced intervals in each sediment core biological particle mixing coefficients were determined via a two box advection diffusion steady state mixing model based on the distribution profiles of excess 210pb and in some cases excess 234th activities the sedimentation rates estimated were in the order of a few millimeters yr except for cores enriched in phosphatic components which displayed rates a few orders of magnitude slower bioturbation was significant in most cores studied with the exception of one core collected from within the middle of the oxygen minimum zone estimated biological mixing coefficients were in the order of 100 101 cm2 yr 1 for the surface mixed layer and 10 1 100 cm2 yr 1 for the layer below sediment slumping appears to have affected the 210pb distribution of two or three of our cores

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

offshore peruvian phosphorite a reappraisal of its age and genesis abstract phosphatic crusts and nodules recovered from the continental margin off peru did not precipitate authigenically from anoxic pore water but were formed in post palaeogene times by phosphatisation of quartzitic and feldspathic carbonate bearing sediments the late quaternary uranium series and amino acid dates obtained for these phosphatic rocks are probably the result of secondary enrichment of organic matter and uranium and probably do not represent the times of phosphate mineralisation

the effects of source rocks and chemical weathering on the petrogenesis of siliciclastic sand from the neto river calabria italy implications for provenance studies plutonic and gneissic rocks of the sila massif in the uppermost portion of the neto drainage basin calabria southern italy weather and erode under a humid mediterranean climate during the development of weathering profiles a combination of chemical weathering and granular disintegration processes occurred chemical weathering involves a loss of both plagioclase mainly during grus generation and k feldspar mainly during soil formation this loss is attributed to transformation of plagioclase to clay minerals and to leaching and dissolution of k feldspar sand composition is quartzofeldspathic and nearly homogeneous along the main channel of the neto river even where the river cuts across a blanket of sedimentary cover thus fluvial transport does not alter sand composition within the neto drainage basin petrographic indices are effective in 1 discriminating between contributions from similar granite and gneiss source rocks qm f 2 relating the provenance of plutoniclastic and gneissiclastic sand found in the headwaters to grus horizons qm f q rg and 3 distinguishing between upstream first cycle and downstream multicycle sand q rg this last distinction is further emphasized by considering both aphanitic and phaneritic varieties of rock fragments rgrmrs diagram chemical weathering is the main sand producer within the regolithic environment in northern calabria in addition rapid erosion resulting from steep slopes removes weathered products and rapid and short transport leads to minimal sediment maturation in general the f q index is climate and relief dependent thus it should be used in conjunction with palaeoclimatic and palaeophysiographic evidence for provenance interpretations of ancient quartzofeldspathic sandstones

new tsunami forecast tools for the french polynesia tsunami warning system part ii numerical modelling and tsunami height estimation tsunami warning is classically based on two fundamental tools the first one concerns the source parameters estimations and the second one is the tsunami amplitude forecast we presented in the first companion paper how the seismic source parameters are evaluated and this second article describes the operational aspect and accuracy of the estimation of tsunami height using tsunami numerical modelling on a dedicated supercomputer 2 5 t flops the french polynesian tsunami warning centre developed two new tsunami forecast tools for a tsunami warning context based on our tsunami propagation numerical model named taitoko the first tool named merit that is very rapid provides a preliminary forecast distribution of the tsunami amplitude for 30 sites located in french polynesia in less than 5 min in this case the coastal tsunami height distribution is calculated from the numerical simulation of the tsunami amplitude in deep ocean using an empirical transfer function inspired by the green law this method which does not take into account resonance effects of bays and harbour is suitable for rapid and first estimation of the tsunami danger the second method named coaster which uses 21 nested grids of increasing resolutions gives more information about the coastal tsunami effects about the flow velocities the arrival time of the maximal amplitude and the maximal run up height for five representative sites in 45 min the historical tsunamis recorded over the last 22 years in french polynesia have been simulated with these new tools to evaluate the accuracy of these methods the results of the 23 historical tsunami simulations have been compared to the tide gauge records of three sites in french polynesia the results which are quite encouraging shows standard errors of generally less than a 2 factor the maximal standard error is 0 38 m for the tahauku bay of hiva oa marquesas islands

the 2010 and 2011 tsunamis in french polynesia operational aspects and field surveys we present a detailed timeline of the warning procedures as they unfolded at the laboratoire de geophysique in papeete tahiti during the nights of 26 27 february 2010 maule chile tsunami and 10 11 march 2011 tohoku tsunami in particular we discuss how the flow of information available to the warning center including seismic evaluations obtained both locally and from other warning centers as well as maregraph and dart buoy data built up and eventually led to red alerts which the local authorities used in both cases to impose an evacuation of low lying areas on 68 islands while the alerts were successful in polynesia a difficulty arose in 2011 when the alert had to be reinstated immediately as the all clear was being declared since the maximum amplitude was carried by the fourth wave packet we also present a complete dataset of 119 values of run up and inundation surveyed in the aftermath of the two tsunamis principally in the marquesas islands where their effects were maximal and on tahiti and moorea for the 2011 event the highest run up 4 45 m was observed in 2011 in the bay of taipivai on nuku hiva where seven houses were flooded we find no clear correlation between run up values at the same locations in 2010 and 2011 suggesting that local responses are controlled by details specific to each tsunami in 2010 in the village of puamau on hiva oa marquesas a delayed harbor response probably due to resonance of the bay upon arrival of short period components dispersed outside the shallow water approximation flung a launch onto a wharf 7 h after the first arrivals and 2 5 h after issuance of the all clear

quantifying particle aggregation in sediments sediments often occur as non normal size distributions composed of discrete partially aggregated particle populations these populations reflect provenance dispersal pathways and their depositional environments recent experimental laboratory studies describing mud flocculation in turbulent marine systems prompted this investigation of the potential of aggregates to record size sensitive transport dynamics in a terrestrial fluvial system here sediment size distributions in their natural condition of particle aggregate mixtures are analysed by parametric statistics a practical and freely available decompositional approach is outlined and field tested which allows sediment to be viewed in both its conventional particulate form and as its naturally occurring mixture of transport stable aggregates and elementary particles from a sequence of upward fining slack water couplets in the flinders ranges south australia it is demonstrated that the characteristics provenance and depositional history of fine grained sediments consisting of particle aggregate mixtures can best be understood fully by quantifying aggregation

influence of mixtures of grain size populations on the parametric and modal characteristics of coastal sands herault mediterranean sea france abstract grain size distributions in lower beach and nearshore sands of a segment of the coast of the golfe du lion france were analyzed by a parametric method and by modal analysis the results have been considered both in a spatial framework delineating geographically distinct sedimentary compartments and cells and in a morphodynamic framework separating the dynamic components of the shoreline berm collision zone inner bar outer bar lower shoreface modal statistics indicate that a mixture of three dominant components end members contributes to the grain size distribution gsd of the sediments fine sand sedimentary type i modal value 0 195 mm i 0 35 medium and coarse sand st ii modal value 0 680 mm i 0 8 and very coarse sand and gravel st iii i modal value 2 3 mm i 1 5 quasi log normal one component gsds form a minority group and mixtures produce various apparently unimodal sands and bimodal sediments a large variation of grain size indices results from mixing a simulation of mixing of log normal populations close to the end members shows the great sensitivity of parameters sorting skewness and kurtosis to small changes in the compositional formula of the mixture the procedure followed supplies a good preliminary tool enabling rapid identification and localization of the main sand sources on a regional scale these components derive from potential sources available in the region well known from previous studies st i originates from the river rhone and provides the textural base for most of the sediments st ii and iii form a local component originating either from fluvial input aude orb and herault rivers or from the nearshore reworking of ancient quaternary sediments and late holocene beachrocks each st takes on local aspects in relation to the morphological environment but the regional scale of the study was too large to precisely reflect the local morphodynamic regime a significant change in the st i sorting of bar sands is however observed probably due to the net offshore migration reported for the bar system

reconstructing a sediment pulse modeling the effect of placer mining on fraser river canada gold mining along 525 km of the fraser river between 1858 and 1909 added an estimated 1 1 108 t of tailings half gravel and the rest finer to the river s natural sediment load we simulate the response using a 1 d multigrain size morphodynamic model since premining conditions are unknown and modern data are insufficient for tuning the process representation we devised a novel modeling strategy which may be useful in other data poor applications we start the model from a smoothed version of the modern longitudinal profile with bed grain size distributions optimized to match alternative assumptions about natural sediment supply and compare runs that include mining with control runs that can be used to quantify the effects of deficiencies in process representation and initialization simulations with an appropriate choice of natural supply rate closely match the best available test data which consist of a detailed 1952 1999 gravel budget for the distal part of the model domain the simulations suggest that the main response to mining was rapid bed fining which allowed a major increase in bed load transport rate with only slight 0 1 m mean aggradation within the mining region and most of the excess sediment exported well beyond the mountain front within the mining period or soon afterward we compare this pattern of response by a large powerful river with previous case studies of river adjustment to sediment supply change

phosphorites hardgrounds and syndepositional solution subsidence a palaeoenvironmental model from the miocene of the maltese islands abstract two major phosphorite conglomerate horizons occur throughout the central mediterranean maltese islands within the lower middle miocene globigerina limestone formation the lower conglomerate lies directly upon a hardground and both conglomerates include lithoclasts of hardground material variation in clast size and bed thickness indicates a source area to the west and north of the present day islands of malta and gozo particularly thick phosphorite conglomerates occur in solution subsidence structures in western gozo being developed as a result of synsedimentary seafloor collapse these structures indicate that phosphorite clasts were deposited during several discrete pulses of turbulence punctuated by periods of non depositional hardground formation or normal marine pelagic sedimentation geochemical analysis of the contained phosphorite clasts within the conglomerates shows that p 2 o 5 generally is concentrated around the outer margins of the pebbles and contributes up to 17 by weight of some samples some 654 580 m 3 and 837 870 m 3 of phosphorite bearing strata are contained within the xlendi and qawra subsidence structures respectively the maltese islands represent part of a miocene carbonate shelf whose margin lay nearby to the west and which was subject to periodic erosion by strong currents transporting phosphorite pebbles eastwards to their present sites these currents further contributed phosphorus to semi autochthonous phosphorite developments located within the present maltese area the maltese phosphorites are related to other phosphorite areas in sicily a major province of miocene phosphogenesis is proposed to account for these occurrences it extends along the western margins of the malta ragusa rise

teleseismic estimates of radiated seismic energy the e m 0 discriminant for tsunami earthquakes we adapt the formalism of boatwright and choy for the computation of radiated seismic energy from broadband records at teleseismic distances to the real time situation when neither the depth nor the focal geometry of the source is known accurately the analysis of a large data set of more than 500 records from 52 large recent earthquakes shows that this procedure yields values of the estimated energy ee in good agreement with values computed from available source parameters for example as published by the national earthquake information center neic the average logarithmic residual being only 0 26 units we analyze the energy to moment ratio by defining log10 ee m0 for regular earthquakes this parameter agrees well with values expected from theoretical models and from the worldwide neic catalogue there is a one to one correspondence between values of that are deficient by one full unit or more and the so called tsunami earthquakes previously identified in the literature as having exceedingly slow sources and believed due to the presence of sedimentary structures in the fault zone our formalism can be applied to single station measurements and its coupling to automated real time measurements of the seismic moment using the mantle magnitude mm should significantly improve real time tsunami warning

downstream variation in bed sediment size along the east carpathian rivers evidence of the role of sediment sources taking as an example six main rivers that drain the western flank of the eastern carpathians a conceptual model has been developed according to which fluvial bed sediment bimodality can be explained by the overlapping of two grain size distribution curves of different origins thus for carpathian tributaries of the siret coarse gravel joins an unimodal distribution presenting a right skewness with enhanced downstream fining the source of the coarse material distributions is autohtonous by abrasion and hydraulic sorting mechanisms a second distribution with a sandy mode is in general skewed to the left the source of the second distribution is allohtonous the quantity of sand that reaches the river bed through the erosion of the hillslope basin terrains the intersection of the two distributions occurs in the area of the 0 5 8 mm fractions where in fact the right skewness for gravel and left skewness for sand histogram tails meet this also explains the lack of particles in the 0 5 8 mm interval for rivers where fine sediment sources are low the 0 5 8 mm fractions have a higher proportion than the fractions under 1 mm for the siret river itself bed sediment bimodality is greatly enhanced due to the fact that the second mode is more than 25 of the full sample as opposed to its tributaries the source of the first mode of gravel is allohtonous to the siret river generated by the massive input of coarse sediment through the carpathian tributaries while the second mode of the sands is local in this case we can also observe that the two distributions of particles of different origins overlap in the 0 5 8 mm fraction domain creating the illusion of particle lack in the fluvial bed sediments copyright 2007 john wiley sons ltd

palaeoecology and evolution of marine hard substrate communities abstract marine organisms have occupied hard substrates since the archaean shells rocks wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space hard substrate communities are formed by organisms with a variety of strategies for adhering to and or excavating the substrates they inhabit while mobile grazers organically attached and even soft bodied organisms may leave evidence of their former presence in ancient hard substrate communities a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils furthermore encrusters and borers are preserved in situ retaining their spatial relationships to one another and to the substrate spatial competition ecological succession oriented growth and differential utilisation of exposed vs hidden substrate surfaces can all be observed or inferred hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years here we review the research on modern and ancient hard substrate communities and point to some changes that have affected them over geological time scales such changes include a general increase in bioerosion of hard substrates particularly carbonate surfaces through the phanerozoic this is at least in part analogous to the infaunalisation trends seen in soft substrate communities encrusting forms show an increase in skeletalisation from the palaeozoic into the mesozoic and cenozoic which may be a response to increasing levels of predation hard substrate communities considering borers and encrusters together show a rough increase in tiering through the phanerozoic which again parallels trends seen in soft substrate communities this extensive review of the literature on living and fossil hard substrate organisms shows that many opportunities remain for large scale studies of trends through time at the community and clade levels palaeontologists will especially benefit by closer integration of their work with that of neontologists particularly in aspects of ecology such as larval recruitment competition and succession

jointed source rock and fluvial gravels controlled by rosin s law a grain size study in calabria south italy the primary distributions of the untransported source rocks are unimodally distributed and very positively skewed the average sand fraction is only 4 only 6 of the distributions are lognormal 94 follow the rosin distribution which is typical for products of technical breakage and milling processes twelve of the 19 river mounth sediments are bimodally distributed with a primary mode in the gravel range a marked valley in the 2 mm range and a secondary mode in the sand range the seven rivers with unimodal sediments also have their modes in the gravel range both unimodal bimodal sediments consist of on the average 74 boulder and gravel 25 sand and 1 silt and clay surprisingly 77 of the gravel modes of the river sediments also follow the rosin distribution only the sand fractions of both the unimodal and bimodal sediments are lognormally distributed the rosin distribution of the calabrian river gravel is interpreted as a source specific primary feature the lognormality of the sand mode in contrast as a transport specific secondary feature since the jointed and weathered source rocks contain only 4 sand they cannot be the only source of the 25 sand in the river sediments the sand must also come from other sources such as soil building and transport wear modified journal abstract

ultra fine structures and genesis of the campanian negev high grade phosphorites southern israel ultra fine structures of the negev high grade phosphorites provide valuable clues to unravelling the genesis of these rocks the question of their differential areal distribution and the biosedimentary mechanisms involved in their considerable enrichment peculiar to these phosphorites is an intergranular phosphate matrix for the most part constituted by a variety of phosphatic microbial tubules displaying a range of spatial micro organizations the phosphate particles fixed by this filamentous meshwork also consists of internally organized and non organized packed microbial remains of different types analogies between the fabrics of the matrix and the corpuscles lead to conception of a two stage depositional scheme for these phosphorites based on rhythmical repetition of two sedimentary mini events in a slightly oscillating very shallow marine system 1 a low energy event of microbial colonization of the mishash bottoms followed by early phosphatization of the organic structures mainly in marginal situations and 2 a higher energy event which broke up the phosphatic mats into debris redepositing them as clastic layers in nearby basinward sites while becoming bound by a new meshwork of filamentous microphytes the differential phosphatization of the intergranular microbial binder again occurring mostly in marginal localities produced highly enriched phosphorites minor truncations and redepositions leading to amalgamation of the successive layers account for the massive fabric now displayed by most of these rocks examining the structural and textural features the validity of the sedimentary mechanisms of recent phosphorite formation for the campanian negev rocks is discussed

new tsunami forecast tools for the french polynesia tsunami warning system this paper presents the tsunami warning tools which are used for the estimation of the seismic source parameters these tools are grouped under a method called preliminary determination of focal mechanism 2 pdfm2 that has been developed at the french polynesia warning center in the framework of the seiscomp3 system as a plug in concept the first tool determines the seismic moment and the focal geometry strike dip and slip and the second tool identifies the tsunami earthquakes earthquakes that cause much bigger tsunamis than their magnitude would imply in a tsunami warning operation initial assessment of the tsunami potential is based on location and magnitude the usual quick magnitude methods which use p waves work fine for smaller earthquakes for major earthquakes these methods drastically underestimate the magnitude and its tsunami potential because the radiated energy shifts to the longer period waves since french polynesia is located far away from the subduction zones of the pacific rim the tsunami threat is not imminent and this luxury of time allows to use the long period surface wave data to determine the true size of a major earthquake the source inversion method presented in this paper uses a combination of surface waves amplitude spectra and p wave first motions the advantage of using long period surface data is that there is a much more accurate determination of earthquake size and the advantage of using p wave first motion is to have a better constrain of the focal geometry than using the surface waves alone the pdfm2 method routinely gives stable results at t 0 45 minutes with t 0 being the origin time of an earthquake our results are then compared to the global centroid moment tensor catalog for validating both the seismic moment and the source geometry the second tool discussed in this paper is the slowness parameter theta and is the energy to moment ratio it has been used to identify tsunami earthquakes which are characterized by having unusual slow rupture velocity and release seismic energy that has been shifted to longer periods and therefore have low theta values the slow rupture velocity would indicate weaker material and bigger uplift and thus bigger tsunami potential the use of the slowness parameter theta is an efficient tool for monitoring the near real time identification of tsunami earthquakes

patterns of grain size distribution in some point bars of the usri river india abstract the patterns of grain size distribution of point bar sediments on the usri river india were compared to log normal log hyperbolic and log skew laplace distribution models sediment samples were collected from a specific size of bedform ranging in foreset thickness from 23 to 40 cm from the source to the mouth of the river over a distance of about 90 km the hydrodynamic parameters of the river were also measured at four point bars the results indicate that a the log normal distribution is the best fitted distribution model among the three distribution models b after a certain distance of transport the log normal distribution becomes log hyperbolic and c though there is a tendency for grain size to decrease downstream within each point bar together with improvement of sorting this pattern is not consistent along the entire course of the usri river from one equivalent bar position to the next or from the source to its mouth

rapid forecast of tsunami wave heights from a database of pre computed simulations and application during the 2011 tohoku tsunami in french polynesia 1 we present a method for the rapid estimation of tsunami wave heights either in the deep pacific basin or at specific shore locations it uses a database of 260 pre computed scenarios of generic sources distributed along the pacific trenches and can provide an estimate of wave heights within minutes of the location of the earthquake and the estimation of its moment the method is tested against a set of dart data and of 51 maregraph records in tahiti and the marquesas islands it was used in real time to successfully predict tsunami amplitudes in polynesia during the 2011 tohoku alert

w phase source inversion for moderate to large earthquakes 1990 2010 rapid characterization of the earthquake source and of its effects is a growing field of interest until recently it still took several hours to determine the first order attributes of a great earthquake e g m w 7 5 even in a well instrumented region the main limiting factors were data saturation the interference of different phases and the time duration and spatial extent of the source rupture to accelerate centroid moment tensor cmt determinations we have developed a source inversion algorithm based on modelling of the w phase a very long period phase 100 1000 s arriving at the same time as the p wave the purpose of this work is to finely tune and validate the algorithm for large to moderate sized earthquakes using three components of w phase ground motion at teleseismic distances to that end the point source parameters of all m w 6 5 earthquakes that occurred between 1990 and 2010 815 events are determined using federation of digital seismograph networks global seismographic network broad band stations and sts1 global virtual networks of the incorporated research institutions for seismology data management center for each event a preliminary magnitude obtained from w phase amplitudes is used to estimate the initial moment rate function half duration and to define the corner frequencies of the passband filter that will be applied to the waveforms starting from these initial parameters the seismic moment tensor is calculated using a preliminary location as a first approximation of the centroid a full cmt inversion is then conducted for centroid timing and location determination comparisons with harvard and global cmt solutions highlight the robustness of w phase cmt solutions at teleseismic distances the differences in m w rarely exceed 0 2 and the source mechanisms are very similar to one another difficulties arise when a target earthquake is shortly e g within 10 hr preceded by another large earthquake which disturbs the waveforms of the target event to deal with such difficult situations we remove the perturbation caused by earlier disturbing events by subtracting the corresponding synthetics from the data the cmt parameters for the disturbed event can then be retrieved using the residual seismograms we also explore the feasibility of obtaining source parameters of smaller earthquakes in the range 6 0 mw 6 5 results suggest that the w phase inversion can be implemented reliably for the majority of earthquakes of mw 6 or larger

muddled or mixed inferring palaeoclimate from size distributions of deep sea clastics abstract one of the outstanding problems of palaeoclimate reconstruction from physico chemical properties of terrigenous deep sea sediments stems from the fact that most basin fills are mixtures of sediment populations derived from different sources and transported to the site of deposition by different mechanisms conventional approaches to palaeoclimate reconstruction from deep sea sediments do not distinguish between provenance and dispersal related variations and therefore often fail to recognise the true significance of variations in sediment properties we formulate a set of requirements that each proposed palaeo environmental indicator should fulfil and focus on the intrinsic coupling between grain size and chemical composition a critical review of past achievements in grain size analysis serves to introduce a conceptual model of spatio temporal grain size variation based on dynamic populations each dynamic population results from a characteristic combination of production and transport mechanisms that corresponds to a distinct subpopulation in the data analysed the mathematical statistical representation of the conceptual model can be obtained by means of the end member modelling algorithm emma applications of the model to several ocean basins are discussed as well as methods to examine the validity of grain size based palaeoclimate reconstructions palaeoclimate reconstructions of a high and low latitude basin illustrate the common degree of complexity of deep sea grain size records

modeling of the february 1996 peruvian tsunami the february 1996 peruvian earthquake generated a larger tsunami than expected from its surface magnitude this discrepancy as well as the long rupture duration indicate that this event is a tsunami earthquake the associated tsunami was strong locally with runup heights of 1 to 5 meters along a coastline of 400 km it is shown that this tsunami can be modeled for a seismic moment of 2 1020 nm using a rigidity of 2 1010 n m the tsunami propagation is modeled solving long wave equations by a finite difference method the maximum run up heights in the region of chimbote can be simulated using a grid increment of 10 meters the propagation of this small tsunami across the pacific ocean is modeled taking into account frequency dispersion the only notable amplification occurred in the marquesas islands where wave heights of 2 meters were observed and are simulated

time and space distribution of coseismic slip of the 2011 tohoku earthquake as inferred from tsunami waveform data a multiple time window inversion of 53 high sampling tsunami waveforms on ocean bottom pressure global positioning system coastal wave and tide gauges shows a temporal and spatial slip distribution during the 2011 tohoku earthquake the fault rupture started near the hypocenter and propagated into both deep and shallow parts of the plate interface a very large slip approximately 25 m in the deep part off miyagi at a location similar to the previous 869 jogan earthquake model was responsible for the initial rise of tsunami waveforms and the recorded tsunami inundation in the sendai and ishinomaki plains a huge slip up to 69 m occurred in the shallow part near the trench axis 3 min after the rupture initiation this delayed shallow rupture extended for 400 km with more than a 10 m slip at a location similar to the 1896 sanriku tsunami earthquake and was responsible for the peak amplitudes of the tsunami waveforms and the maximum tsunami heights measured on the northern sanriku coast 100 km north of the largest slip the average slip on the entire fault was 9 5 m and the total seismic moment was 4 2 1022 n m m w 9 0 the large horizontal displacement of seafloor slope was responsible for 20 40 of tsunami amplitudes the 2011 deep slip alone could reproduce the distribution of the 869 tsunami deposits indicating that the 869 jogan earthquake source could be similar to the 2011 earthquake at least in the deep plate interface the large tsunami at the fukushima nuclear power station is due to either the combination of a deep and shallow slip or a triggering of a shallow slip by a deep slip which was not accounted for in the previous tsunami hazard assessments online material table of estimated slip for all subfaults at 0 5 min invervals

origin of basaltic soils at gusev crater mars by aeolian modification of impact generated sediment 1 textural properties of soils including grain size sorting modality skewness shape quantified as sphericity and qualified as form roundness and grain size distribution have been measured and calculated from microscopic imager mi high resolution images from the mars exploration rover mer spirit in gusev crater soil targets were classified by grain size into five groups fine to medium sand dark soil medium sand to very fine pebble bed form armor and very fine to medium pebble lithic fragments a bimodal mixed soil and an excavated soil trench the abundance of submature very poorly sorted bimodal mixed soils indicates incomplete sorting by soil type probability distributions of excavated subsurface soil match crushed sediment analogs indicating impact comminution while all other soils show no direct evidence of an impact origin if soils were produced primarily by impacts then the evidence from probability distributions angular shapes and agglutinates have been reworked by postimpact surface activity soils in gusev crater are continuously modified reworked and sandblasted textures of surface sediments are disconnected from subsurface textures and only reflect modern surficial aeolian processes models to reconstruct physical and chemical soil formation properties should not assume a static three dimensional structure a three step model initiated by the formation of basaltic crust and its alteration followed by bolide impact and finally modification by aeolian reworking is envisioned for the formation of soils such a scenario accounts for the potential that surface sediments may be compositionally and texturally distinct from the subsurface

lithological controls on hillslope sediment supply insights from landslide activity and grain size distributions the volumes rates and grain size distributions of sediment supplied from hillslopes represent the initial input of sediment delivered from upland areas and propagated through sediment routing systems moreover hillslope sediment supply has a significant impact on landscape response time to tectonic and climatic perturbations however there are very few detailed field studies characterising hillslope sediment supply as a function of lithology and delivery process here we present new empirical data from tectonically active areas in southern italy that quantifies how lithology and rock strength control the landslide fluxes and grain size distributions supplied from hillslopes landslides are the major source of hillslope sediment supply in this area and our inventory of 2800 landslides reveals that landslide sediment flux is dominated by small shallow landslides we find that lithology and rock strength modulate the abundance of steep slopes and landslides and the distribution of landslide sizes outcrop scale rock strength also controls the grain sizes supplied by bedrock weathering and influences the degree of coarsening of landslide supply with respect to weathering supply finally we show that hillslope sediment supply largely determines the grain sizes of fluvial export from catchments and that catchments with greater long term landslide rates deliver coarser material therefore our results demonstrate a dual control of lithology on hillslope sediment supply by modulating both the sediment fluxes from landslides and the grain sizes supplied by hillslopes to the fluvial system

fluvial conglomerates in continental red beds of the buntsandstein lower triassic in the eifel f r g and their palaeoenvironmental palaeogeographical and palaeotectonic significance abstract fluvial conglomerates occur in a variety of facies within the continental red bed sequence of the buntsandstein lower triassic in the eifel at the western margin of the mid european triassic basin the alluvial rudites are classified into channel floor lag channel bar channel top lag crevasse splay and floodplain lag conglomerates the conglomerates were predominantly deposited in scott type and in subordinate amounts also in donjek type and south sasketchewan type braided rivers the vertical distribution of clast size and frequency within the megacycles reflects the palaeotectonic sequence of uplift events in the source area resulting in supply of large amounts of coarse detritus which cause recurrences in fluvial style gradually upwards diminishing size and abundance of gravel indicate continuous lowering of source area relief during weakening endogenic activity or even tectonic quiescence after final peneplanation the palaeoenvironmental interpretation of the individual members and the palaeotectonic analysis of the conglomerate successions are combined with a reconstruction of the depositional history of the eifel buntsandstein which comprises an evolution of fluvial deposition the terminal stage of the palaeoenvironmental evolution is highlighted by a climax of regional diversification of conglomerate sedimentary milieu the horizontal distribution of clast size and abundance delineates the palaeogeographical evolution of the elongated eifel basin giving evidence of a progressive sidewards extension of the depositional area with time lateral supply from parts of the western margin and mixing of proximally derived coarse clasts with distantly delivered fine detritus result in highly inhomogeneous gravel distributions within the sedimentary region often not being characterized by gradually decreasing size and abundance of gravel in downstream direction the stepwise southwestwards shift of the marginal centre of supply of coarse gravel with time during the course of the lateral extension of the basin results in ascension of the fluvial conglomerate wedges into successively younger formations comprising consecutively middle buntsandstein upper buntsandstein lower muschelkalk middle muschelkalk and finally middle keuper the extraformational conglomerates mainly delineate the palaeogeographical framework whereas the intraclastic rudites primarily give evidence of processes operating within the depositional area reflecting erosion and reworking of overbank sequences with floodplain fines palaeosols and aeolian dune sands during lateral channel shift the brockelbank intraformational carbonate breccias to conglomerates originating from reworking of calcrete palaeosols are a peculiar facies element with particularly high palaeoenvironmental significance they document the frequency spatial extension and temporal persistence of pedogenesis within the alluvial plain the size of the extraformational clasts gives evidence of the range of current velocities during aggradation of the channels the distribution of conglomerate type and clast characteristics within cyclothems indicates the presence of stage fluctuations and variations in discharge in parts of the sequence the preservation of complete cyclothems or the multistoreying of channel bar conglomerates reflects the differential importance of the two main mechanisms controlling accumulation of sediments in the alluvial plain primary depositional restriction to suppression of formation and secondary erosional removal to destruction of finer grained channel sediments floodplain deposits and aeolian dune sands or palaeosols condensation of a series of depositional events within monotonous stacked conglomerate sequences obliterates the full range of sedimentary processes and mimics periods of long term stability of conglomerate formation waning flow mud drapes are particularly significant instruments to split up the individual genetical units of formation of fluvial conglomerates often comprising discrete flood phases separated by stage fluctuations of different magnitude the homogeneous or microcyclic composition of the coarse member reflects uniphase or multiphase aggradation of watercourses with gradually declining or abruptly waning individual flood periods the fluvial rudites thus are of high significance in the reconstruction of the depositional milieu in the eifel buntsandstein and provide a key to detailed interpretation of palaeoenvironmental processes palaeogeographical constellations and palaeotectonic events which could not have been identified to such an extent in exclusively sandy sequences