climatic fluctuations reflected in the evolution of fluvial systems of central eastern europe 60 8 ka cal bp abstract in general the evolution of fluvial systems in central eastern europe reflects the main phases of climatic changes during the period of 60 8 ka cal bp registered in greenland ice cores and their isotopic 18 o curves the greenland isotope curve shows many more wiggles and stages than the fluvial record of the same time especially during the interpleniglacial phase in central eastern europe we observe several deviations from those climatic trends connected with different factors among which are the long distance of the region from the atlantic ocean and an increase in continentality at times this region was occupied by permafrost although the coexisting warm summers during a part of the studied period enabled the presence of a forest cover these factors together controlled the specific features of the fluvial regime and sediment load reflected in alternating trends to erosion or aggradation and from meandering to braiding the permafrost influenced snowmelt floods and tendency to braiding the dense vegetation with trees reduced the supply of sediments and stabilized the meandering channels very distinct changes occurred in the river valleys that drain the mountains where ceaseless fluctuations of vegetation vertical zones were present especially during the unstable interpleniglacial when the supply of load from the higher vegetation zones was increased this system controlled by the climate and plant vegetation was modified by other factors including tectonics wind activity during dry periods blocking of valleys by ice sheets meltwater supply and sea level fluctuations of two reservoirs

some effects of weathering on joints in granitic rocks abstract standard engineering weathering classifications most of which are based on weathered granite typically describe the appearance and condition of the weathered material e g whether or not it is friable the condition of individual minerals e g degree of pitting and micro cracking and changes in mineral composition and the degree of staining on joint surfaces or the distance that staining extends into rock from the joints these classifications do not address changes in frequency length and appearance of joints in the rock mass as weathering progresses this account of work on vertical or steeply dipping joints in granitic rocks shows that not only are there statistically significant differences in mean joint spacings and mean trace lengths with increased weathering but that the physical appearances of joints also changes as weathering progresses mean joint spacing is wide in fresh rock becomes closer in moderately weathered rock and then becomes progressively wider from moderately weathered rock through highly and completely weathered rock mean joint lengths follow a similar but inverse pattern mean trace lengths become shorter from fresh to slightly weathered rock lengthen in moderately weathered rock then progressively become shorter from moderately weathered rock through highly and completely weathered rock furthermore joint appearance changes with increased weathering joints in fresh rock are sharp edged and typically straight the edges begin to round in moderately weathered rock and in highly weathered rock joint traces become sinuous and discontinuous around mineral grains in completely weathered rock the only visible joints are filled with minerals or marked with iron staining it is proposed that this evolution in joint pattern and appearance results from increased cracking along grain boundaries and thermal expansion of individual mineral grains and within grain micro cracking as weathering proceeds these factors allow individual mineral grains to move into the spaces between joint surfaces thus obscuring individual joints and making them appear shorter these apparent changes in joint properties could lead to incorrect rock mass classification and thus to inappropriate engineering design and costly errors during construction

computation of wind wave spectra in coastal waters with swan on unstructured grids abstract an unstructured grid procedure for swan is presented it is a vertex based fully implicit finite difference method which can accommodate unstructured meshes with a high variability in geographic resolution suitable for representing complicated bottom topography in shallow areas and irregular shoreline the numerical solution is found by means of a point to point multi directional gauss seidel iteration method requiring a number of sweeps through the grid the approach is stable for any time step while permitting local mesh refinements in areas of interest a number of applications are shown to verify the correctness and numerical accuracy of the unstructured version of swan

size and spatial distributions of fault populations empirically synthesized evolution laws for the fractal geometries 1 we performed fractal analysis for 10 fault populations that are developed in continuous outcrops of neogene sedimentary rocks a transect line was set with reference to the principal stress axes and the position and displacement of all faults that intersect the transect line were measured precisely we found that both the fractal dimension of the size net slip frequency and that of the spatial distribution of fault displacements are determined by only two parameters an input energy density and a dissipative energy density these two kinds of fractal dimension evolve decrease as the ratio of the input energy to the dissipative energy increases and are tied by a universal equation

a high resolution coupled riverine flow tide wind wind wave and storm surge model for southern louisiana and mississippi part ii synoptic description and analysis of hurricanes katrina and rita abstract hurricanes katrina and rita were powerful storms that impacted southern louisiana and mississippi during the 2005 hurricane season in part i the authors describe and validate a high resolution coupled riverine flow tide wind wave and storm surge model for this region herein the model is used to examine the evolution of these hurricanes in more detail synoptic histories show how storm tracks winds and waves interacted with the topography the protruding mississippi river delta east west shorelines manmade structures and low lying marshes to develop and propagate storm surge perturbations of the model in which the waves are not included show the proportional importance of the wave radiation stress gradient induced setup

integration of ice core marine and terrestrial records intimate refining the record of the last glacial interglacial transition integration of ice core marine and terrestrial records intimate is a core project of the inqua palaeoclimate commission the primary goal of which is to synchronise records of the last glacial interglacial transition lgit through a series of international workshops intimate has encouraged direct collaboration between scientists with interests and expertise in a wide range of palaeoenvironmental approaches the workshops have focused on the dissemination of good practice in the dating correlation and synthesis of diverse palaeoenvironmental records that span the lgit this special issue of quaternary science reviews presents some of the outcomes of the 8th intimate international workshop held in iceland in september 2005 and focuses on four themes considered vital to intimate s long term strategy 1 an event stratigraphy approach which uses the greenland oxygen isotope record as a stratotype sequence lies at the core of intimate s operations a revised event stratigraphy scheme for application to north atlantic lgit records is presented which is based on the new gicc05 greenland ice core chronology 2 new tree ring data from switzerland and the application of bayesian based procedures in the analysis of comprehensive radiocarbon data sets provide much potential for reducing the uncertainties in radiocarbon based age models 3 three of the contributions present new evidence that helps to refine the tephrostratigraphy of the lgit in the ne atlantic and new zealand regions 4 establishing the precise order and synchroneity of events during the lgit is vital to understand the causes and effects of abrupt climate change data are presented from the baltic region and alaska which vary in degree of compatibility with north atlantic records two final papers consider the roles of dansgaard oeschger events on thermokarst during the middle weichselian and of solar activity variations during the mid holocene both illustrate how the intimate event stratigraphy approach can apply to the study of other time intervals

shear localization in transformation induced faulting first order similarities to brittle shear failure abstract transformation induced faulting a leading candidate for the mechanism of deep focus earthquakes leads to catastrophic shear failure in laboratory specimens by the growth and coalescence of microscopic mode i anticracks or packets of denser microcrystalline transformed material we have studied this phenomenon in mg 2 geo 4 olivine undergoing a polymorphic phase transformation to its denser spinel phase at 2 7 gpa and 1200 k under applied stress in order to better understand the details of anticrack growth and coalescence which leads to localized shear zones and macroscopic failure here we report observations that address the early stages of shear localization preserved in one experiment of this series are microstructures typical of anticrack nucleation and growth as well as those involved in the self organization of these features during the shear localization process we have analyzed sem and optical images of individual anticrack reaction interfaces and coalesced structures from this experiment and another experiment conducted under similar conditions but with a different strain history we have isolated the reaction boundaries in these images and have performed fractal analysis of these boundary lines we find that the fractal dimension of isolated uncoalesced anticrack structures is consistently higher than that of structures formed from coalescence and coarsening of fine grained reaction products this result is consistent with the varying effects of stress and thermal feedback at these interfaces and also represents an interesting parallel with the fractal nature of brittle cracks and fault surfaces we also measured the length of the long axis of uncoalesced anticrack structures found in the experiment arrested at failure and find a roughly log normal distribution of sizes very similar to the distribution of microcrack lengths reported in experiments involving brittle shear failure microcracks and microanticracks both also commonly nucleate on grain boundaries intracrystalline flaws and phase boundaries shear zones faults formed by either of these mechanisms also regularly form at 30 to maximum compression from this set of observations we conclude that the general phenomenon of shear failure creates similar features in both systems perhaps in any system which generates a shear instability despite the major differences in the detailed microphysics because of the detailed and unambiguous measurements that are possible with images of transformation induced faulting experiments further studies of this faulting mechanism may provide new insights into brittle failure and shear localization processes

fractal analysis of fracture patterns using the standard box counting technique valid and invalid methodologies abstract on the basis of results of simple box counting analysis it has been suggested in several recent publications that natural fracture patterns are fractal fractal patterns are characterized by self similarity of structure on a range of scales and provide straight line distributions on box counting plots new analysis of a fracture pattern that provided the most convincing straight line box counting curve previously published shows that the curve is non linear and therefore that the fracture pattern is not fractal non linear box counting curves are also characteristic of other natural fracture patterns analysed but spurious linear curves can be obtained if the area analysed extends beyond the mapped area

numerical study of critical behaviour of deformation and permeability of fractured rock masses abstract the connectivity of fractures in rock masses is determined using a numerical simulation method there is a continuous fracture cluster throughout a fractured rock mass if fracture density d is at or above a threshold fracture density d c fractal dimension d f is used to describe the connectivity and compactness of the largest fracture clusters d f increases with increasing fracture density percolation theory is used to determine the universal law d f a f d d c f which describes the critical behaviour of connectivity of fractures in rock masses the results from numerical modeling show that the deformability of fractured rock masses increases greatly with increasing fracture density i e fractal dimension and the critical behaviour of deformability can be described by b s a d d f s also the overall permeability of a fractured rock mass occurs at or above a critical fracture density d c and increases with increasing fracture density the critical behaviour of permeability can be described by q a p d d c p the critical behaviour of connectivity and permeability of naturally fractured rock masses is examined using the universal forms

fluvial history of the sub carpathian basins poland during the last cold stage 60 8 cal ka bp abstract the fluvial landforms of the last cold stage are represented in the sub carpathian basins by a system of 2 3 terraces which grade into alluvial fans of a height of 15 20 8 12 and 6 8 m above the present riverbeds in the mountain foreland in the vistula river valley the 15 20 m high terrace covered with loess extends along the western margin of the sandomierz basin and northern margin of the carpathians away from the mountain margin it passes into the sandy terrace plain with dunes it is formed of at least two interpleniglacial alluvial fills the older one dated at 48 36 ka bp over 50 40 6 ka cal bp and the younger one dated 30 25 ka bp 34 1 29 0 ka cal bp thus pertaining to the upper pleniglacial this latter forms a terrace 15 m high in general accumulation of fluvial sediments interrupted with erosion phases dominated in the mountain foreland during the period 60 25 ka bp over 60 29 ka cal bp the most significant erosion phase took place before the maximum extension of the vistulian weichselian wisconsinian ice sheet i e before 25 20 ka bp 29 24 ka cal bp and was connected with a change from an oceanic to a more continental climate the next alluvial fill of terrace 8 12 m high with remnants of braided river channels was formed at the end of the upper plenivistulian the incision of the river channels below the present channel level was followed by aggradation in the late vistulian 15 13 ka bp 18 2 15 6 ka cal bp accompanied by a change in river channel system from braided to meandering in the wisloka and san river valleys alluvial plains extending by lateral erosion of large meanders were abandoned by rivers mainly in the younger dryas and the preboreal the late vistulian large palaeomeanders are missing along lower sola and lower dunajec these rivers fed from higher mountains had still tendency to braiding the climate cooling of the younger dryas brought an increase in the delivery of bedload to the river channels and a tendency to braiding in vistula valley drwinka depression the expansion of forest in the early holocene reduced the water discharge and the size of meanders as a result their width fallen by 3 5 times alluvial data showed also a distinct humid climatic phase ca 9 5 8 5 ka cal bp

the generation of internal waves on the continental shelf by hurricane andrew observed currents temperature and salinity from moored instruments on the louisiana continental slope and shelf reveal multiple baroclinic oscillations during hurricane andrew in august 1992 these measurements are supplemented by numerical models in order to identify possible internal wave generation mechanisms the princeton ocean model is run with realistic topography stratification and wind forcing to extend the observations to mississippi canyon and other areas on the shelf a two layer isopycnal model is used with idealized topography and spatially uniform winds to isolate internal waves generated in and around the canyon the combination of the observations and the results from the numerical models indicates several possible mechanisms for generating long internal waves 1 near inertial internal waves were generated across the slope and shelf by dislocation of the thermocline by the wind stress 2 interaction of inertial flow with topography generated internal waves along the shelf break which bifurcated into landward and seaward propagating phases 3 downwelling along the coast depressed the thermocline after downwelling relaxes an internal wave front propagates as a kelvin wave and 4 poincare waves generated within mississippi canyon propagate seaward while being advected westward over the continental slope these processes interact to produce a three dimensional internal wave field which was only partly captured by the observations

fault spacing in the el teniente mine central chile evidence for nonfractal fault geometry we utilize the excellent rock exposure provided by the network of mining tunnels in el teniente mine central chile to test the applicability of fractal fault spacing laws to a 2 km 3 km 1 3 km body of crystalline rock in an andean shear zone fractal spacing laws can be particularly useful because they allow prediction of fault spacing at unsampled scales because of the restrictions of tunnel geometry in the mine we use only scanline one dimensional analyses the large number of parallel tunnels allows us to assess the consistency of one dimensional scanline samples over a two dimensional area we use two methods 1 an interval counting technique and 2 standard cumulative statistics to test the hypothesis of fractal fault geometry in the shear zone the interval counting method produces deceptively good fits to a fractal distribution in fact by analyzing the residuals and differential slopes of interval counting and cumulative statistical plots and by comparison with synthetic fractal negative exponential and log normal distribution data we conclude that a negative exponential distribution best describes fault spatial distribution at the mine we present three possible explanations for the negative exponential spacing distribution 1 the rock body is at the earliest stage in a deformational path that will produce varying spacing distributions as deformation proceeds 2 the spacing distribution is inherited through joint reactivation and 3 the present spacing distribution is the result of a superposition of two spacing distributions each of which is not necessarily negative exponential additionally we attempt to use the deviation of mean spacings in parallel scanlines after wu and pollard 1995 to further classify deformational maturity we show that this method cannot be used to compare population development in faults which follow a negative exponential spacing distribution because of the negative exponential s equivalence of mean and standard deviation instead we use a relative measure of parallel scanline deviation to compare regions the distinctly smaller standard deviation of mean spacings in one region the t3 isla region may be a signature of increased local finite strain accumulation

an integrated forecast system over the mediterranean basin extreme surge prediction in the northern adriatic sea abstract a previsional system for the forecast of the state of the mediterranean sea and of surges in the northern adriatic sea has been designed and tested the system consists of a limited area model the bologna limited area model bolam which computes high resolution pressure and surface wind fields to serve as the input of a wave model wam and of a shallow water model two dimensional princeton ocean model pom 2d results of two case studies are presented chosen to test the ability of the system to predict extreme surge events originating from cyclonic circulation over the mediterranean basin the two case studies cover the periods 4 9 october 1998 and 11 22 november 1996 comparison with observed buoy data shows that the results of the wam simulations forced by the wind fields obtained from the high resolution bolam model are significantly better than those obtained using a lower resolution forcing from the ecmwf analyses two domains corresponding to the entire mediterranean basin and to th

ducted coastal ridging over s e australia the intense and rapidly established coastal ridging which is a regular occurrence over south eastern australia during the warm seasons is investigated using a detailed case study and mesoscale numerical model simulations we suggest that the ridge is initiated by a forced kelvin type edge wave which forms on the south western edge of the great dividing range and is ducted in an anticlockwise sense around the coast the ridge is then stabilized by inertial modification and decays over a synoptic time scale of a few days our results apply to similar phenomena in other parts of the world notably southern africa and south america

the connectivity of two dimensional networks of spatially correlated fractures 1 continuum percolation thresholds for fracture systems are based on models with random fracture locations resulting in uniformly clustered systems in which all connections are fracture intersections fractures in natural systems can be either clustered or anticlustered and a significant portion of the connectivity is achieved through fracture abutments or splays analytical and numerical methods are combined to define critical properties of isotropic networks of constant length lines as a function of fracture clustering and of the ratio of abutments to intersections a second suite of numerical results indicates that the influence of these parameters varies as a function of the fracture length distribution a preliminary predictor of critical density of anisotropic nonrandom systems with lognormal length distributions is derived and applied to a suite of natural fracture systems predicted connectivities are closer to the observed connectivities when the predictor is used than when connectivity is estimated from the random threshold

a basin to channel scale unstructured grid hurricane storm surge model applied to southern louisiana abstract southern louisiana is characterized by low lying topography and an extensive network of sounds bays marshes lakes rivers and inlets that permit widespread inundation during hurricanes a basin to channel scale implementation of the advanced circulation adcirc unstructured grid hydrodynamic model has been developed that accurately simulates hurricane storm surge tides and river flow in this complex region this is accomplished by defining a domain and computational resolution appropriate for the relevant processes specifying realistic boundary conditions and implementing accurate robust and highly parallel unstructured grid numerical algorithms the model domain incorporates the western north atlantic the gulf of mexico and the caribbean sea so that interactions between basins and the shelf are explicitly modeled and the boundary condition specification of tidal and hurricane processes can be readily defined at the deep water open boundary the unstructured grid enables highly refi

fractured but not fractal fragmentation of the gulf of suez basement recent geophysical studies revealed that the palaeozoic basement of the gulf of suez consists of an enormous number of fault blocks whose network qualitatively resembles the contractioncrack polygons which can be found in nature in a wide variety of materials and on all scales mud cracks hardening concrete age cracking in paintings etc the fault network of the gulf of suez basement forms a rather uniformly spaced polygonal pattern most of the blocks are four sided the lengths of block sides parallel with the gulf of suez axis are exponentially distributed the power law size distribution associated with the fractal scale free fragmentation can be possibly ruled out

poleward propagating subinertial alongshore surface currents off the u s west coast 1 the network comprising 61 high frequency radar systems along the u s west coast uswc provides a unique high resolution and broad scale view of ocean surface circulation subinertial alongshore surface currents show poleward propagating signals with phase speeds of o 10 and o 100 300 km d 1 that are consistent with historical in situ observations off the uswc and that can be possibly interpreted as coastally trapped waves ctws the propagating signals in the slow mode are partly observed in southern california which may result from scattering and reflection of higher mode ctws due to curvature of shoreline and bathymetry near point conception california on the other hand considering the order of the phase speed in the slow mode the poleward propagating signals may be attributed to alongshore advection or pressure driven flows a statistical regression of coastal winds at national data buoy center buoys on the observed surface currents partitions locally and remotely wind forced components isolates footprints of the equatorward propagating storm events in winter off the uswc and shows the poleward propagating signals year round

fractal dimension of fault systems in japan fractal structure in rock fracture geometry at various scales based on fault maps whether or not the fracture geometry of rocks is self similar was examined by using a box counting algorithm the statistical self similarity fractal structure of the fault fracture systems holds well at the scale of about 2 to 20 km the fractal dimension in japan varied from 1 05 to 1 60 the fractal dimension is about 1 5 1 6 at the central part of the japan arc and decreases with distance from the center at a smaller scale the fractal structure also holds well in the rock fracture geometry the fractal dimension of the north izu peninsula fault system branching faults is 1 49 at the scale of 0 625 to 10 km the fractal dimension of rock fracture geometry at the scale order of 10 1 to 10 2 meters is about 1 49 1 61 the upper limit of the fractal dimension of rock fracture geometry is about 1 6 judging from the estimation of fractal dimension on actual fracture geometry of rocks this value may impose a restraint on modeling of faulting and the fracture process of rocks

structural and statistical characterization of joints and multi scale faults in an alternating sandstone and shale turbidite sequence at the santa susana field laboratory implications for their effects on groundwater flow and contaminant transport abstract this paper describes the properties of faults and fractures in the upper cretaceous chatsworth formation exposed at santa susana field laboratory and its surroundings simi hills california where groundwater flow and contamination have been studied for over three decades the complex depositional architecture of this turbidite consisting of alternating sandstones and shales interacting with formative stress conditions are responsible for multi scale fault hierarchies and permeable fractures in which nearly all groundwater flow occurs intensity and distribution of background fractures and their relation to bedding thickness are established for sandstones the dominant lithology the architecture of faults with increasing displacement is described and relationships among fault dimensional parameters captured data from 400 boreholes and piezometers reveal the effect of faults and fractures on groundwater flow large hydraulic head differences observed across fault zones with shale rich cores indicate these structures as cross flow barriers moreover hydraulic head profiles under ambient conditions and pumping tests suggest strong hydraulic connectivity in all directions to depth of hundreds of meters this outcrop based structural characterization relates the horizontal hydraulic conductivity to the observed well connected fracture network and explains the strong vertical connectivity across low hydraulic conductivity shales as faults and sheared fractures provide flow pathways

geometrical and fractal analysis of a three dimensional hydrothermal vein network in a fractured granite abstract a three dimensional study of a fracture network has been performed on a 0 66 m 3 block of fine grained granite from la peyratte deux sevres france the block was sawn in nine parallel plates the fractures associated with altered haloes were mapped for each plate using a photographic method the nine fracture sets were subjected to an analysis of the percolated network based on a measurement of the width of altered haloes developed around fractures hydrothermal alteration is created by circulation of a certain amount of fluid flow in the rock we assume that the alteration zone width is proportional to fluid mass flow the width of alteration zones will give a good idea of the path preferentially followed by fluids the relation between fracture length and width of the alteration zone shows that the total fracture network consists in fact of two sorts the largest fractures surface 0 1 m 2 create a loose and poorly interconnected pattern in the block however they have developed wide alteration zones 3 mm and have then had a great role in fluid conduction they represent only 10 of the fractures but are responsible for 47 of alteration in volume approximately 80 of these fractures with wide alteration zones are oriented in the same direction this main network is linked to a more dense highly interconnected system made of shorter fractures with narrower altered zones fractal analysis has also been performed on pictures of the fracture patterns using the linear cantor s dust method fractal dimension values d indicate an anisotropy of fracture distribution on each plane moreover when the planes are compared to one another in succession variations of d values can be noticed indicating an inhomogeneity in the third dimension the study of such a three dimensional fracture set shows that fluids follow preferential paths within a fracture network and helps the understanding of fracture distribution

measurement and characterisation of spatial distributions of fractures abstract a variety of line sample 1 d and map 2 d datasets of faults and joints has been used to investigate the spatial distributions of fractures and to test techniques of fractal analysis the natural fracture datasets have been supplemented by synthetic datasets with known characteristics the fault datasets investigated range in scale from regional to outcrop and the joint datasets are derived from outcrop 1 d datasets were analysed by the spacing population interval counting and fracture number interval counting techniques 2 d datasets were analysed by box counting and fracture number box counting techniques results indicate that fracture spacing can be characterised in line samples using either the 1 d interval counting technique or more simply by measuring the spacing population as the cumulative frequency distribution of spaces between adjacent fractures tectonic faults frequently show a power law spacing population indicating fractal dimensions of between 0 4 and 1 0 but except for outcrop data truncation effects degrade the analysis unrefined joint datasets commonly show negative exponential or lognormal spacing cumulative frequency distributions however single orientation joint sets are characterised by a regular spacing and are therefore non fractal for both fault and joint map data box counting techniques do not yield the power law relationship between box size and the number of boxes that is expected of fractal geometries it is concluded that 2 d box counting techniques are too insensitive to characterise the many different parameters of a fracture array the fracture density technique appears not to discriminate between very different fracture patterns and therefore does not provide useful results a fracture pattern incorporates several attributes e g size distribution orientation linkage density roughness each of which may scale independently and each of which may be fractal with its own fractal dimension full characterisation of fracture patterns will therefore require independent analysis of each of these attributes

deglaciation constraints in the parâng mountains southern romania using surface exposure dating cosmogenic nuclide surface exposure ages have been widely used to constrain glacial chronologies in the european regions this paper brings new evidence that the romanian carpathians sheltered mountain glaciers in their upper valleys and cirques until the end of the last glaciation twenty four 10be surface exposure ages were obtained from boulders on moraine crests in the central area of the par ng mountains southern carpathians exposure ages were used to constrain the timing of the deglaciation events during the late glacial the lowest boulders yielded an age of 13 0 1 1 1766 m and final deglaciation occurred at 10 2 0 9 ka 2055 m timing of the late glacial events and complete deglaciation reported in this study are consistent with and confirm previously reported ages of deglaciation within the carpathian and surrounding european region

hurricane gustav 2008 waves and storm surge hindcast synoptic analysis and validation in southern louisiana abstracthurricane gustav 2008 made landfall in southern louisiana on 1 september 2008 with its eye never closer than 75 km to new orleans but its waves and storm surge threatened to flood the city easterly tropical storm strength winds impacted the region east of the mississippi river for 12 15 h allowing for early surge to develop up to 3 5 m there and enter the river and the city s navigation canals during landfall winds shifted from easterly to southerly resulting in late surge development and propagation over more than 70 km of marshes on the river s west bank over more than 40 km of caernarvon marsh on the east bank and into lake pontchartrain to the north wind waves with estimated significant heights of 15 m developed in the deep gulf of mexico but were reduced in size once they reached the continental shelf the barrier islands further dissipated the waves and locally generated seas existed behind these effective breaking zones the hardening and innovative deployment of gauges since hur

implications from the comparisons between two and three dimensional model simulations of the hurricane ike storm surge 1 we apply the finite volume coastal ocean model to simulate the hurricane ike storm surge using two dimensional 2 d and three dimensional 3 d formulations the high resolution unstructured grid extends over the gulf of mexico with open boundaries in the straits of florida and the yucatan channel with the same wind and pressure forcing the bottom drag coefficients for the baseline 2 d and 3 d simulations are determined by spatially varying manning coefficients and constant bottom roughness respectively the baseline 2 d model simulates both the forerunner and the surge whereas the baseline 3 d model simulates the surge but underestimates the forerunner increasing the minimum manning coefficient reduces the 2 d forerunner and the surge manning coefficient and bottom roughness parameterizations produce different bottom drag coefficients using the same bottom drag coefficient the 2 d simulation yields a smaller surge than in three dimensions this is investigated for scenarios of either constant or variable bottom roughness where the bottom roughness is determined through manning coefficient transformation these sensitivity studies indicate that storm surges simulated either in two dimensions or three dimensions depend critically upon the parameterizations and the parameter values used for specifying bottom stress and similar may be said of surface stress given suitable calibration 2 d and 3 d models may adequately simulate storm surge however it is unclear that a calibration for a given storm and location may apply generally hence additional experimental guidance is required on the parameterizations and the parameter values used for both the surface and bottom stresses under severe wind conditions

resonance of long waves generated by storms obliquely crossing shelf topography in a rotating ocean the oceanic forced wave beneath a moving atmospheric disturbance is amplified by proudman resonance when modified by the earth s rotation this classical resonance only occurs if the disturbance time scale is smaller than the inertial period with or without coriolis effects free transients generated by storm forced waves obliquely crossing step changes in water depth at particular angles are shown to resonate by exciting a range of barotropic free waves rotationally influenced slow atmospherically forced waves crossing a vertical coast at a critical angle lead to a form of sub critical resonance which occurs only when the component of the disturbances phase velocities along the coast matches that of a free kelvin wave kw in a rotating ocean transients generated by disturbances crossing a step at a particular angle are shown to excite a free double kelvin wave dkw this new type of resonance only occurs for sufficiently large steps and disturbances with time scale greater than the inertial period a storm crossing a step shelf can result in the excitation of an infinite set of edge waves a single kw a unique dkw and a first mode continental shelf wave depending on the topography and the disturbance time scale translation speed and incident angle the study of resonances and wave mode excitations generated by storms crossing a coast or a continental shelf may contribute to understanding how a particular combination of the storm characteristics can result in destructive coastal events with time scales encompassing the typical meteotsunami period band tens of minutes and storm surges with periods of several hours or days

fault growth in brittle ductile experiments and the mechanics of continental collisions using laboratory models of continental collisions we study the mechanisms responsible for large scale deformation and the nature of the penetrative deformation localized or homogeneous and its characteristic scales and structure in order to focus the study one of the most spectacular cases of continental collisions namely the india asia collision is considered different models with varying rheologies are analyzed which attempt to respect the brittle ductile stratification corresponding to the crust and mantle structure in the earth each experiment is quantified by studying the strain field and the fault pattern as a function of the position p of the indenter within the system the strain field is characterized by 1 the second invariant of the two dimensional strain tensor and its variation with position for a fixed p the evolution of its average as a function of p 2 the evolution with p of the participation ratio s2 which quantifies the fraction of the system surface area which participates in the deformation 3 the evolution of the escape ratio calculated as the surface increase gained by the system during its eastward lateral escape divided by the surface covered by the indenter penetration qualitatively we find that the deformation first spreads out but later on undergoes localization once the fault pattern is mature the cumulative fault length does not increase anymore we observe that the strain field is essentially controlled by the kinematics of the larger faults each fault pattern is quantified by studying 1 the histograms of fault orientations 2 the capacity and barycenter fractal dimensions 3 the multifractal generalized dimensions and 4 the distribution of fault lengths the fractal dimension d is found to almost constant within experimental uncertainty d 1 7 0 1 and thus appears rather insensitive to the particular chosen rheology we find a correlation between the generalized multifractal dimensions and two exponents the barycenter fractal dimension b and the exponent a of the fault length distribution this shows that the scaling properties of fault patterns can be characterized by the knowledge of only two exponents b and a of the spatial and length distributions of faults our main results are 1 observation of the growth of self similar fault patterns 2 complete characterization of the fault patterns with two scaling exponents a and b 3 wide distribution of undeteriorated domains and large heterogeneity of the deformation field 4 maturation of the fault structure corresponding to a localization of the deformation on a few large faults in the late stage of the deformation

fracture spacing and orientation distributions for two dimensional data sets a new automated method is developed for the measurement and display of fracture spacing and orientation from two dimensional 2 d fracture maps separate histograms of fracture spacing are calculated at different orientations through the 2 d data set the histograms for all orientations are plotted together reducing the biasing effects associated with one dimensional 1 d sampling of a fracture population quantitative measurements of fracture strike anisotropy and fracture density are incorporated in the plot no prior measurements are needed of parameters such as fracture spacing orientation or width the data do not have to be preprocessed into a numerical vector format saving time and reducing user bias the method retains the relative frequency of different ranges of fracture spacings which are lost in other fracture frequency measures such as fracture intensity density thus the presence of any dominant rather than average fracture spacing and fracture clustering is highlighted the method provides a quantitative statistically unbiased representation of fracture orientation and spacing and is illustrated on synthetic and real fracture data sets at a range of scales from meters to tens of kilometers its application to a seismic energy scattering problem is also discussed

remote forcing contribution to storm induced sea level rise during hurricane dennis 1 numerical model experiments are conducted to address the previously unexplained anomalously high storm surge along the florida coast of apalachee bay during hurricane dennis 2005 the 2 3 m surge observed during this storm cannot be obviously explained by the relatively weak local winds over this bay 275 km east of the storm center realistic and idealized numerical experiments demonstrate that the along shore winds to the east of the storm center built a high sea level anomaly along the coast which traveled northward to apalachee bay as a topographic rossby wave the wave was amplified as the storm moved nearly parallel to the shelf and at comparable speed to the wave phase speed these results suggest that enlarging the domain of the storm surge forecasting models can improve the surge forecast for a storm moving along a similar track and have now been applied to operational use

regional and local changes inferred from lacustrine organic matter deposited between the late glacial and mid holocene in the skaliska basin north eastern poland abstract the article presents the results of a combination of isotopic 15 n and 13 c geochemical toc tn c n and palaeobotanical investigations they were carried out on organic matter om that had been deposited from the younger dryas to the subboreal chronozone in palaolake sediments north eastern poland om from the late younger dryas consists only a small amount of toc and tn which together with the lack of aquatic macrophyte macrofossils confirm low primary production in the then reservoir the higher values of c n ratio 18 27 and 13 c ca 26 suggest that om was mainly terrestrial in origin during the preboreal chronozone 11 450 10 150 cal bp there was a probable deepening of the reservoir through the melting of dead ice this might have been intensified by an increase in precipitation and a fall in evapotranspiration during the preboreal oscillation from the early preboreal chronozone ca 11 345 cal bp a mixed source of om is indicated by c n ratio from 8 to 13 at the same time significant increase in toc and tn probably registered a rise in primary production in the palaeolake from the older part of the boreal chronozone ca 9865 cal bp algae productivity increased the c n ratio dropped to ca 8 and was then constant at the beginning of the atlantic chronozone ca 8650 cal bp a probable increase in the water level caused the partial relocation of om from the reed swamp belt and or the adjacent alder carr into deeper sections of the palaeolake an increase in toc and tn in the late atlantic chronozone ca 6965 6650 cal bp toc and tn decreased while 13 c had high values which probably reflected a more distinct stratification of the water column with anoxic bottom waters next in the late atlantic and early subboreal chronozone ca 6650 5205 cal bp the amount of om in palaeolake sediments was still rising the 13 c values dropped suggesting an intensification of processes of water mixing these processes were simultaneous with the constant shallowing of the palaeolake and the disappearance of habitats suitable for submerged macrophytes the topmost part of the profile is characteristic of a strong decomposition of peat causing a release of carbon dioxide and therefore the depletion of the carbon pool in the peat a drop in the c n ratio the concurrent upward trend of the 15 n curve is probably the effect of a greater anthropogenic impact on the palaeolake mire and its catchment and or more recent human interference in the topmost peat layers

shallow water currents during hurricane andrew oceanographic measurements are used in combination with a numerical model to examine the influence of stratification on shallow water currents during the directly forced stage of a tropical cyclone hurricane andrew on the continental shelf the following stratification dependent coastal processes are examined 1 turbulent mixing 2 coastally trapped waves 3 near inertial oscillations and 4 upwelling and downwelling turbulent mixing was strong within 1 rw radius of maximum winds of the storm track and stratification was nearly destroyed turbulent mixing was weak at distances greater than 2 rw the dominant coastal wave was a barotropic kelvin wave generated as the storm surge relaxed after landfall baroclinic near inertial oscillations were dominant at the shelf break and occurred along with a barotropic response on the middle shelf downwelling favorable flow developed east of the track prior to the storm peak and upwelling favorable flow evolved west of the track as the eye crossed the shelf the idealized storm flow was modified by local barotropic and baroclinic pressure gradients on the shelf ocean circulation during hurricane andrew was hindcast using both stratified and unstratified three dimensional numerical models for areas within 1 rw of the storm track the unstratified model matched the observed currents better than the stratified model partly because of errors in the initial stratification at distances greater than 2 rw the influence of stratification increases and the unstratified model does not reproduce the observed upwelling favorable flow

late glacial and early holocene lake level fluctuations in ne poland tracked by macro fossil pollen and diatom records abstract late glacial and early holocene vegetation history and lake level fluctuations in ne poland were described based on high resolution plant macrofossils analyses and records of pollen diatoms and radiocarbon dates the development of lake kojle perty began in the allerod gi 1c cooling during the younger dryas gs 1 led to the development of communities of heliophyte herbaceous plants palaeobotanical and lithostratigraphical records demonstrate that abrupt climate changes at approximately 11 600 and 9450 cal bp resulted in distinct changes in the vegetation and water level of lake kojle perty climate warming in the younger dryas holocene transition 11 600 cal bp caused the development of the terrestrial vegetation dominated by cold deciduous forest betula and appearance of thermophylious aquatic plants typha latifolia najas marina and ceratophyllum demersum a gradual decrease in the lake level since 11 200 cal bp is evident from the appearance of plants from shallow lake environments potamogeton natans and hippuris vulgaris the low water levels since 10 700 cal bp resulting from increased temperature and evaporation caused the development of peat on limnic sediments the dry and warm climatic phase with lowest lake level in the lakes of ne poland were coeval with the expansion of temperate deciduous forests corylus and ulmus that commenced at approximately 10 500 cal bp a distinctive increase in lake levels at approximately 9450 cal bp is suggested by the development of rush plants such as cladium mariscus and aquatic plants such as najas marina chara sp and nuphar lutea in the shallow parts of lake kojle perty the increased lake levels correspond with the expansion of alnus glutinosa in north east ne poland our reconstructions of the vegetation development and lake level changes align with results from other studies in the region

extending the area of investigation of fine versus coarse quartz optical ages from the lower danube to the carpathian basin despite the general satisfactory performance of quartz in the single aliquot regeneration protocol sar previous optically stimulated luminescence osl dating studies of key loess sections in romania lower danube region revealed a disturbing disagreement among the ages obtained on fine 4 11 m grains and coarse 63 90 m grains respectively the current study aims at expanding these investigations both by extending the area of study from the lower danube basin to the carpathian basin and by applying time resolved optically stimulated luminescence tr osl on quartz in order to gain further insights into the above mentioned behaviour the samples from the orlovat loess paleosol section vojvodina serbia showed a similar behaviour to that previously reported on romanian loess a marked difference between the dose saturation characteristics of fine and coarse quartz osl signals is observed for both continuous wave cw osl and pulsed osl posl where the dose response up to 1000 gy is well described by a sum of two saturating exponential functions tr osl measurements show one single characteristic quartz lifetime for both natural as well as regenerative signals in the entire dose range investigated a general disagreement between the ages obtained on the two grain sizes for samples with equivalent doses higher than about 100 gy is reported as in the case of romanian loess inferring that the age discrepancy between the two grain sizes might be more widespread than previously thought

critical stress localization of flow associated with deformation of well fractured rock masses with implications for mineral deposits fluid flow and deformation of fractured rock masses is investigated using numerical models based on distinct element methods udec which couple mechanical and hydraulic behaviour a series of numerical experiments is presented in which diffuse flow through fracture networks changes to highly localized flow at a critical stress state slip on parts of the fracture network causes the opening up of some fractures often at fracture intersections thus a change in the stress state results in a sudden localization of deformation and fluid flow a series of plots of hydraulic conductivity v differential stress are presented for some natural fracture networks to demonstrate the influence of fracture network geometry and in situ stress on the critical phase boundary between diffuse and localized flow the onset of localized deformation and fluid flow is a critical point phenomenon resulting in fractal properties fractal and multifractal techniques are used to characterize heterogeneity of the flow in order to generalize the results of the modelling of discrete systems to a continuum based description of the flow the significance of the models and their implications for crustal behaviour are discussed in relation to hydrothermal mineralization and natural vein systems

kelvin type coastal surges generated by tropical cyclones abstract measurements of sea level along the coat of western australia during the period 1969 to 1982 when 12 southward moving tropical cyclones occurred showed distinct peaks with amplitudes of about 1 to 2 m propagating southwards with speeds ranging between 400 600 km day 1 similar observations of sea level along the east coast of australia during the period 1971 to 1980 of 7 southward moving tropical cyclones showed no such peaks these data suggest that the large peaks occurring on the west coast are a result of a resonance phenomenon when the southward component of the cyclone speed is close to that of southward propagating shallow water kelvin waves 11 is shown that the coastal response to moving atmospheric forcing fields may be described by a kelvin type disturbance which at any instant is confined to a localized coastal region dependent on the kelvin wave speed and the longshore speed of the tropical cyclone this region expands in the longshore direction at a rate equal to the difference

quantitative summer and winter temperature reconstructions from pollen and chironomid data between 15 and 8 ka bp in the baltic belarus area abstract new pollen based reconstructions of summer may to august and winter december to february temperatures between 15 and 8 ka bp along a s n transect in the baltic belarus bb area display trends in temporal and spatial changes in climate variability these results are completed by two chironomid based july mean temperature reconstructions the magnitude of change compared with modern temperatures was more prominent in the northern part of bb area the 4 c winter and 2 c summer warming at the start of gi 1 was delayed in the bb area and lateglacial maximum temperatures were reached at ca 13 6 ka bp being 4 c colder than the modern mean the younger dryas cooling in the area was 5 c colder than present as inferred by all proxies in addition our analyses show an early holocene divergence in winter temperature trends with modern values reaching 1 ka earlier 10 ka bp in southern bb compared to the northern part of the region 9 ka bp

origin of the hurricane ike forerunner surge 1 a large unpredicted water level increase appeared along a substantial section of the western louisiana and northern texas latex coasts 12 24 hrs in advance of the landfall of hurricane ike 2008 with water levels in some areas reaching 3 m above mean sea level during this time the cyclonic wind field was largely shore parallel throughout the region a similar early water level rise was reported for both the 1900 and the 1915 galveston hurricanes the ike forerunner anomaly occurred over a much larger area and prior to the primary coastal surge which was driven by onshore directed winds to the right of the storm track we diagnose the forerunner surge as being generated by ekman setup on the wide and shallow latex shelf the longer forerunner time scale additionally served to increase water levels significantly in narrow entranced coastal bays the forerunner surge generated a freely propagating continental shelf wave with greater than 1 4 m peak elevation that travelled coherently along the coast to southern texas and was 300 km in advance of the storm track at the time of landfall this was at some locations the largest water level increase seen throughout the storm and appears to be the largest freely propagating shelf wave ever reported ekman setup driven forerunners will be most significant on wide shallow shelves subject to large wind fields and need to be considered for planning and forecasting in these cases

fractal and multifractal measures of natural and synthetic fracture networks we have analyzed the fractal and multifractal nature of a series of 17 natural fracture trace maps representing a wide variety of scales geological settings and lithologies as well as a number of typical synthetic fracture networks in which fracture locations orientations and lengths are drawn from various probability distribution functions recent studies have shown that multifractal methods can be used to investigate fracture networks at greater depth since the fractal dimension represents only part of the scaling spectrum characterizing each network we find that the real and synthetic fracture maps display fractal and multifractal properties moreover the properties of the synthetic networks are very similar to those of the real networks with nontrivial fractal dimensions and multifractal spectra we suggest that different fracturing mechanisms can lead to two or more distinct subranges over which a fractal dimension can be defined while the heterogeneity of the rock and the nature of the fracturing mechanisms lead to multifractal properties we also find that the fractal dimension of a synthetic fracture network is relatively insensitive to parameters such as fracture length and orientation but can be controlled by appropriate choice of the relative fracture density

quantitative characterization of fracture structure in coal based on image processing and multifractal theory abstract the characterization of fracture structures is key for evaluating the permeability of coalbed methane cbm reservoirs and an interconnected fracture network is essential for the production of cbm taking the upper permian coal in the eastern yunnan and western guizhou region as an example we systemically studied the characteristics of coal deformation and fracture development through direct observation of coal faces and hand specimens an image processing technique was used to obtain high resolution fracture images with an actual resolution of approximately 2 m followed by the statistics of the porosity parameters such as micro fracture density intersection point density and plane areal porosity the multifractal theory was applied to study the micro fracture structures of the coal and a practical algorithm and corresponding technical procedure was proposed to characterize the multifractal characteristics of coal fractures the quantitative characterization of the heterogeneity of the whole and partial fracture structure was then performed and the indicating significance of the generalized dimension spectrum the singularity spectrum and the calculated characteristic parameters was described our results suggest that the micro fracture structures of coal are multifractal which can be measured by combining image processing and multifractal methods the fracture development and the distribution heterogeneity in the target coal seams show significant differences both vertically and laterally coal seam groups with well developed fracture systems and high connectivity were identified by combining macro and micro scale fracture observations and multifractal characterization including the 8 12 coal seam group in the tucheng mining area the 3 7 group of the yueliangtian mine in the pan guan mining area the 8 12 group in the pan guan mining area the 13 18 group in the enhong mining area and the 3 7 group in the laochang mining area

the evolution of the great hungarian plain fluvial system fluvial processes in a subsiding area from the beginning of the weichselian abstract in the great hungarian plain ghp one of the most complex fluvial systems of europe developed through tectonic and climatic factors and vegetation change the aim of the present study is to summarise these controlling factors and to describe the evolution of the ghp special attention is paid to the latest results on late weichselian and holocene development in the tisza river and their effects on the river s largest tributary the maros river several tectonically active subsiding basins existing in the ghp have determined the direction of river courses and erosional accumulational fluvial processes as a result of uneven subsidence the river s flow routes have shifted frequently for example the danube and the tisza shifted 80 100 km abandoning their alluvial fans where extensive aeolian processes started upstream from the subsiding areas incision propagated headward which resulted in the development of floodplain levels and terraces though climate and vegetation changes also simultaneously influenced the rivers hydro morphology channel pattern changes were found just along the margin of the plain and only meandering paleo channels remained in the center of the ghp during dry and cold periods braided patterns appeared in the alluvial fans most likely the result of abundant sediment supply and due to the inability of sparse riparian vegetation to stabilise the banks effectively based on paleo discharge calculations by the end of the pleistocene the rivers of the ghp produced three to eight times more discharge than they do currently and discharge levels continuously decreased during the holocene however due to the long length of the rivers there is a considerable time lag between the response rates of the different river sections which makes creating paleo hydrological reconstructions even more difficult

fractal analysis of fracturing in two african regions from satellite imagery to ground scale abstract in two test areas of africa the fractal character of fracture fields was analyzed at very different scales on fracture maps from satellite images and from interpretation of drainage networks on topographical maps aerial photographs and ground photographs three different methods were used and the results criticized it was generally found that the area studied in western africa displays more fractal features than the area examined in central africa this might be related to the number and mechanism of fracturing phases in each region

a high resolution coupled riverine flow tide wind wind wave and storm surge model for southern louisiana and mississippi part i model development and validation abstract a coupled system of wind wind wave and coastal circulation models has been implemented for southern louisiana and mississippi to simulate riverine flows tides wind waves and hurricane storm surge in the region the system combines the noaa hurricane research division wind analysis system h wind and the interactive objective kinematic analysis ioka kinematic wind analyses the wave model wam offshore and steady state irregular wave stwave nearshore wind wave models and the advanced circulation adcirc basin to channel scale unstructured grid circulation model the system emphasizes a high resolution down to 50 m representation of the geometry bathymetry and topography nonlinear coupling of all processes including wind wave radiation stress induced set up and objective specification of frictional parameters based on land cover databases and commonly used parameters riverine flows and tides are validated for no storm conditions while winds wind waves hydrographs and high wa

u s ioos coastal and ocean modeling testbed evaluation of tide wave and hurricane surge response sensitivities to mesh resolution and friction in the gulf of mexico 1 this paper investigates model response sensitivities to mesh resolution topographical details bottom friction formulations the interaction of wind waves and circulation and nonlinear advection on tidal and hurricane surge and wave processes at the basin shelf wetland and coastal channel scales within the gulf of mexico tides in the gulf of mexico are modestly energetic processes whereas hurricane surge and waves are highly energetic the unstructured mesh coupled wind wave and circulation modeling system swan adcirc is implemented to generate modeled tidal harmonic constituents and hurricane waves and surge for a hurricane ike 2008 hindcast in the open ocean mesh resolution requirements are less stringent in achieving accurate tidal signals or matching hurricane surge and wave responses however coarser resolution or the absence of intertidal zones decreases accuracy along protected nearshore and inland coastal areas due to improper conveyance and or lateral attenuation bottom friction formulations are shown to have little impact on tidal signal accuracy but hurricane surge is much more sensitive especially in shelf waters where development of a strong shore parallel current is essential to the development of ike s geostrophic setup the spatial and temporal contributions of wave radiation stress gradients and nonlinear advection were charted for ike nonlinear advection improves model performance by capturing an additional 10 20 cm of geostrophic setup and increasing resonant cross shelf waves by 30 40 cm wave radiation stress gradients improve performance at coastal stations by adding an extra 20 40 cm to water levels

a compilation of western european terrestrial records 60 8 ka bp towards an understanding of latitudinal climatic gradients terrestrial records of past climatic conditions such as lake sediments and speleothems provide data of great importance for understanding environmental changes however unlike marine and ice core records terrestrial palaeodata are often not available in databases or in a format that is easily accessible to the non specialist as a consequence many excellent terrestrial records are unknown to the broader palaeoclimate community and are not included in compilations comparisons or modelling exercises here we present a compilation of western european terrestrial palaeo records covering entirely or partially the 60 8 ka intimate time period the compilation contains 56 natural archives including lake records speleothems ice cores and terrestrial proxies in marine records the compilation is limited to include records of high temporal resolution and or records that provide climate proxies or quantitative reconstructions of environmental parameters such as temperature or precipitation and that are of relevance and interest to a broader community we briefly review the different types of terrestrial archives their respective proxies their interpretation and their application for palaeoclimatic reconstructions we also discuss the importance of independent chronologies and the issue of record synchronization the aim of this exercise is to provide the wider palaeo community with a consistent compilation of high quality terrestrial records to facilitate model data comparisons and to identify key areas of interest for future investigations we use the compilation to investigate western european latitudinal climate gradients during the deglacial period and despite of poorly constrained chronologies for the older records we summarize the main results obtained from nw and sw european terrestrial records before the lgm

observation of a fast continental shelf wave generated by a storm impacting newfoundland using wavelet and cross wavelet analyses abstract wavelet and cross wavelet power spectra of sea level records from tide gauges along the atlantic coast of canada showed a low frequency barotropic response after hurricane florence crossed the newfoundland shelf in september 2006 in comparison with two other storms the results showed that florence was the only one that excited a propagating sea level disturbance with a period range similar to the passage time of the storm over the shelf 26 30 h and phase shifts consistent with a barotropic continental shelf wave csw the high amplitude of the oscillations generated by florence along the shore diminished from approximately 45 to 12 cm as the csw propagated from the south coast of newfoundland to the southern nova scotia seaboard this paper presents the first direct measurement of a remarkably high alongshore group speed 11 4 5 9 m s 1 in the manner of free barotropic csw by examination of sea level wavelet power spectra at different locations furthermore using cross wavelet analysis

a fractal constitutive model for unsaturated flow in fractured hard rocks abstract a physical conceptual model for water retention in self similar fractured hard rocks is presented the geometric pattern of the fracture network is described using a classical fractal object known as the sierpinski carpet assuming this type of geometry a relatively simple closed form expression for the water content is obtained all model parameters can be calculated from the density of the main fractures the maximum and minimum values of the fracture aperture and the residual water content the resulting water content expression is then used to estimate the unsaturated hydraulic conductivity of the fractured medium based upon the well known model of burdine it is found that for large enough ranges of fracture apertures the new constitutive model converges to the empirical brooks corey model

a late glacial paleolake record from an up dammed river valley in northern transylvania romania lake sediments from the magherus valley in the lowlands of northern transylvania provide new evidence of paleoenvironmental development in romania during the late glacial the studied sediments were deposited as a result of the damming of a small river valley following a series of mass wasting events that occurred during the deglaciation period a continuous sedimentary sequence belonging to the former lake is preserved in the banks of the stream and contains evidence of paleoenvironmental changes associated with the late glacial interstadial bolling allerod or greenland interstadial 1 gi 1 and the late glacial stadial younger dryas or greenland stadial 1 gs 1 implying that the hallmark climatic episodes of northwestern europe are also expressed in eastern europe we employ a multiproxy approach based on the analysis of sediment composition and texture mineral magnetism organic macrofossils and radiocarbon dating the reconstructed paleoenvironmental evolution at the site captures the warm and humid conditions associated with gi 1 as well as the subsequent cooling concomitant with the onset of gs 1 these climatic events are paralleled by vegetation shifts in the region as deduced from comparisons with pollen sequences from magherus and neighboring locations in transylvania and the carpathians the late glacial interstadial was warmer and wetter as evidenced by increased organic matter content in the lake decreased erosion in the catchment development of palustrine plant communities in the proximity of the lake and expansion of spruce during the allerod gi 1c a the late glacial stadial was colder and dryer as indicated by low sedimentary organic matter content an increase in erosion markers and the decline of spruce and its replacement by birch the landscape was more open as herbs and grasses also expanded during this time these fluctuations imply that late glacial climatic events are well expressed not only in upland areas of romania but also in lowland regions such as the transylvanian basin where climatic effects are expected to be more muted c 2014 elsevier ltd and inqua all rights reserved

the role of melting dead ice on landscape transformation in the early holocene in tuchola pinewoods north poland abstract on the basis of macrofossil and pollen analyses ams 14 c dating and geomorphological investigations we reconstructed the development of hydrological changes during the lateglacial to early holocene transition in tuchola pinewoods bory tucholskie in northern poland in this region the wda river flows in polygenetic valleys typical for the young glacial landscape of the northern central european lowlands the middle section of this river provides a suitable setting to demonstrate the environmental and hydrological changes in the late glacial and early holocene because 1 it is a small and well defined area and 2 the existence of a morphologically preserved river valley from late glacial period in this study we focused on a short terrestrial sediment core 48 cm that represents four phases of landscape evolution during the early holocene telmatic lacustrine lacustrine fluvial and alluvial abrupt changes in lithology and sediment structures exhibit rapid changes and threshold processes in environmental conditions the ams 14 c dating of terrestrial plant remains revealed an age for the basal sediments of 11 223 23 cal bp and thus falls within the preboreal biozone plant macrofossil indicators provide evidence of water level and edaphic changes in the basin the results of our study demonstrate a strong influence of melting buried ice blocks on the geomorphological development hydrological changes in the catchment and the biotic environment in the early holocene

coastal trapping and funneling effects on storm surges in the meghna estuary in relation to cyclones hitting noakhali cox s bazar coast of bangladesh abstract studies are described that use a fine resolution numerical model and incorporate the islands and detailed bottom topography of the meghna estuary they show that depending on the characteristics of the atmospheric cyclone and the astronomical tide storm surges can be coastal trapped in the meghna estuary and propagate like edge waves along the coastline causing widespread devastation and enormous loss of life and property the funneling effect of the narrowing estuary acts strongly on the pressure response and predominantly in the region north of sandwip island the combination of coastal trapping and the funneling effect results in the widespread nature of the surges in the meghna estuary the widespread nature of the surges is directly proportional to the wind inflow angle and to the radius of maximum cyclonic wind but inversely proportional to the angle of crossing of the cyclone as made with the coastline the cyclone striking the noakhali chittagong coast produces more widespread surges th

a numerical study of the storm surge generated by tropical cyclone jane abstract in 1983 tropical cyclone jane crossed the north west coast of australia generating a storm surge currents associated with this storm surge were recorded at two offshore moorings south of the cyclone track the data from these moorings are suggestive of the propagation of a continental shelf wave between the two stations this hypothesis is tested by carrying out a numerical simulation of this storm surge based on the depth integrated shallow water equations with wind wave enhanced bottom friction analysis of the numerical results shows that the storm surge can be interpreted as due to continental shelf waves

fractal analysis of fractures applied to soultz sous forets hot dry rock geothermal program abstract a fractal analysis has been performed on a fracture set observed on granite cores in order to determine preferential paths for fluids injected during hot dry rock hdr geothermic experiments this analysis was based on the sorting of fractures on criteria such as their direction according to the present stress field their dip their hydrothermal filling thickness vein width which is linked to the intensity of alteration and thus to the physico chemical properties of the surrounding rock the results show a global increase of the fractal dimension d with depth which may be related to the lithostatic pressure gradient analysis of the total fracture set has showed zones in which fractures are clustered low d values while others are characterized by regularly spaced fractures higher d values fractures parallel to the maximum horizontal stress narrow veins and fractures with a dip greater than 40 represent 35 to 79 of the total fracture set their fractal dimensions are similar to those of the total fracture set large veins linked with high porosity zones show a cluster pattern all along the drilling in the context of hdr geothermics one should seek highly fractured zones especially if the fractures they contain are clustered and if they have developed wide alteration zones linked to a high porosity these conditions may optimize the hdr heat exchanger possibilities

fractal analysis of fractures in rocks the cantor s dust method abstract the cantor s dust method of fractal analysis has been used to describe the regularity of fracture patterns in geological materials seen on a two dimensional surface this linear method of analysis is well adapted to a determination of two dimensional phenomena the determination of the fractal dimension d indicates that it varies regularly as a function of the orientation of the analysis direction this is taken to indicate that there is a relation unexplained as yet between the regularity of the fracture pattern and the forces which produced it the use of the cantor s dust method on naturally fractured materials ranging in dimension from 3 mm to 45 m in maximum dimension indicates the fractal nature of the fractures found in natural materials the analysis method can also be used to identify local variations in the stress field which caused failure such as the fractures in a feldspar compared to those in the host granite etc the method appears to be a sensitive descriptive measure of the failure patterns in rocks

data and numerical analysis of astronomic tides wind waves and hurricane storm surge along the northern gulf of mexico the northern gulf of mexico ngom is a unique geophysical setting for complex tropical storm induced hydrodynamic processes that occur across a variety of spatial and temporal scales each hurricane includes its own distinctive characteristics and can cause unique and devastating storm surge when it strikes within the intricate geometric setting of the ngom while a number of studies have explored hurricane storm surge in the ngom few have attempted to describe storm surge and coastal inundation using observed data in conjunction with a single large domain high resolution numerical model to better understand the oceanic and nearshore response to these tropical cyclones we provide a detailed assessment based on field measurements and numerical simulation of the evolution of wind waves water levels and currents for hurricanes ivan 2004 dennis 2005 katrina 2005 and isaac 2012 with focus on mississippi alabama and the florida panhandle coasts the developed ngom3 computational model describes the hydraulic connectivity among the various inlet and bay systems gulf intracoastal waterway coastal rivers and adjacent marsh and built infrastructure along the coastal floodplain the outcome is a better understanding of the storm surge generating mechanisms and interactions among hurricane characteristics and the ngom s geophysical configuration the numerical analysis and observed data explain the 2 m s hurricane induced geostrophic currents across the continental shelf a 6 m s outflow current during ivan the hurricane induced coastal kelvin wave along the shelf and for the first time a wealth of measured data and a detailed numerical simulation was performed and was presented for isaac

the fractal nature of structural controls on ore formation the case of the iron oxide copper gold deposits in the carajas mineral province brazilian amazon the formation of ore minerals in hydrothermal deposits is the result of a complex interplay between physical and chemical processes that are conditioned by the geologic environment in which they occur in the last decades research has increasingly indicated that many of these processes display different forms of scale invariance i e they show fractal geometry this suggests that behind the apparent disorder and irregularity of the geometry of mineral deposits at different scales an underlying regular pattern is present if properly understood this regular geometrical pattern could be useful in a variety of theoretical and applied fields a great portion of this scale invariance is given by the structural framework during mineralization because structures are a dominant factor controlling fluid flow here we assess the geometry of iron oxide copper gold iocg mineralization in the world renowned carajas mineral province focusing on one of the largest and most economically important orebodies the sossego deposit the geometry of mineralization is evaluated at the microscale ore minerals in thin sections local scale orebodies in mine maps and regional scale deposit distribution on regional maps we show that the spatial distribution and shape of ore minerals at the microscale is largely nonrandom presents fractal geometry and displays defined trends in spatial distribution and anisotropy additionally the geometric trends observed at the microscale mimic those of the local scale geometry of orebodies as well as the regional scale distribution of mineralization the main property controlling the observed scale invariance is permeability which is intrinsically associated with structures at multiple scales these results contribute to further understanding the fractal nature of processes controlling mineral deposit formation and revealing new multiscale approaches to investigate structural controls on ore deposition

fractal clustering of metamorphic veins metamorphic veins record the fracture controlled flow of fluids throughout the oceanic and continental crust i show that the spatial distributions of veins from three diverse metamorphic settings are fractal and self similar vein densities were measured by counting the number of macroscopic veins intersected along linear transects the localities included wol lastonite quartz veins in marbles for which the fractal dimension d is 0 46 actinolite chlorite veins in hydrothermally altered oceanic diabases d 0 81 and epidote quartz veins in contact metamorphosed basalts d 0 25 0 63 the fractal clustering of veins provides a geometric framework for understanding spatial and temporal patterns of fluid flow and mineral reaction during metamorphism