sea salt aerosol groundwater salinization in the litorale romano natural reserve rome central italy a yearly survey in a piezometric network was realized in the litorale romano natural reserve rome central italy collecting water table and chemo physical data monthly chemo physical surveys highlighted a groundwater salinization variability in a coastal unconfined aquifer the aquifer is mostly composed by aeolian sands of a still preserved dune ridge environment on which a pine forest develops the groundwater salinity variability resulted is connected to the wind pattern and rainfalls in fact wind speed higher than 4 m s is responsible for generating sea salt aerosols ssa from sea surface a statistical analysis was performed for wind with a speed higher than 4 m s to detect wind orientation the dry deposition of ssa on the tree foliage appeared correlated to the westerly winds blowing in the springtime when the rainy season occurs the ssa is washed out from the trees and it is directed to groundwater where an enhancement of the electrical conductivity ec values is noticed whenever rain events occur and winds are not westerly a dilution of groundwater salinity takes place and consequently a reduction of ec chemical analyzes were realized as well they confirmed that groundwater of piezometers located close to the coast line is enriched of ssa elements

the influence of river discharge on tidal damping in alluvial estuaries abstract the tidal range the difference between high water level and low water level along an alluvial estuary can be described by savenije s analytical equation journal of hydrology 243 2001 205 215 analytical equation this equation was derived from the complete st venant equations in a lagrangian reference frame in the derivation of that equation the effect of river discharge was disregarded measurements in the schelde estuary show that this assumption is only valid in the lower part of the estuary but that in the upper part the river discharge has an influence on tidal damping in the downstream part of the estuary where the cross sectional area is large compared to the cross sectional area of the river it is correct to disregard the river discharge however in the upstream part of the estuary where the cross sectional area approaches that of the river the fresh water discharge gains importance over the tidal flow and affects the tidal range in this paper the derivation of the analytical equation is expanded to include the effect of the river discharge it is demonstrated that the river discharge can have a considerable influence on tidal damping in the upper reach of the estuary the river discharge affects tidal damping primarily through friction a critical point along the estuary is the point where there is a single slack upstream of which the fresh water velocity is larger than the tidal velocity the location of this point varies with the river discharge from that point onwards the effect of river discharge on damping is dominant it is the point where the estuary becomes primarily of riverine character

inversion styles in the songliao basin northeast china and estimation of the degree of inversion abstract two inversion patterns fault reactivated and cover folded inversions are recognized in the songliao basin of northeastern china mild inversion with a reactivated fault showing normal separation in all synrift beds moderate partial inversion and total inversion are the common styles of fault reactivated inversion the magnitude of extension by rifting as well as orientation of the synrift faults in relation to the compressional direction during inversion significantly controlled the inversion structures the same amount of shortening may produce a moderate inversion style where the normal slip during the rifting was large but a total inversion in which the initial normal slip was small the cover folded inversions in the songliao basin have either no normal faults or have one or more normal faults that occurred prior to inversion and remained dormant during the inversion the geometry of cover folded inversion may be controlled by deep faults in the basement a graben like basement fault assemblage can result in an antiformal geometry while a horst like basement fault assemblage may control a synformal cover folded inversion an inversion with antiformal geometry of the sedimentary sequences is the major style in the songliao basin a new method of estimating the degree of fault inversion is discussed the degree of fault inversion is the ratio between reverse slip during inversion and normal slip during extension both measured along the fault it can be estimated in most fault reactivated inversions where the top of the basement or the floor of the synrift deposits does not fold during the inversion the horizontal inversion ratio represents the relative amount of shortening and extension of a structure or basin it can be used to analyse the degree of inversion of complex structures or basins however both fault inversion and horizontal inversion ratios are primarily influenced by the amount of extension if undergoing same amount of shortening a structure with a small amount of extension may have a much greater inversion ratio than one with a large amount of extension

detailed log stratigraphic study of the lower cretaceous in the danish central trough north sea abstract a detailed log stratigraphic study was conducted on the lower cretaceous cromer knoll group in the sten 1 i 1 nora 1 elin 1 bo 1 and adda 1 wells in the danish central trough six major 24 intermediate and a number of minor log units were identified and correlated between the wells the log units are defined by consistent log trends and are separated by distinct shifts in log readings the log units are isochronous within the resolution of the biostratigraphy and are calibrated to the standard chronostratigraphic scale a good correlation between the log units and published seismic stratigraphy was established in the homogeneous lower cretaceous clay marl and chalk deposits the log stratigraphic method used is seen to be an important correlation tool supplementing the biostratigraphy and seismic stratigraphy a detailed log stratigraphic subdivision of the lower cretaceous has been established depositional hiatuses were found and subsidence and uplift patterns of different subbasins are described the overall successive changes in the lithological character of the major log units coincide with the long term fluctuations of the haq et al eustatic sea level curve

relay ramp forms and normal fault linkages canyonlands national park utah fieldwork within a series of mesoscale grabens in southeast utah has revealed a particularly well exposed system of interlinked extensional faults a series of down faulted grabens are developed within a 460 m thick brittle layer of upper paleozoic sandstone and shale which overlies a ductile layer with a high gypsum content all the major grabens consist of two or more overlapping elements which are composed of fault segments these segments may be hard linked fault surfaces are joined or soft linked fault surfaces are isolated but linked by ductile strain of the rock volume between them in map view relay structures are defined as zones connecting the footwalls and hanging walls of overlapping fault segments representing soft linkage of fault segments in the canyonlands grabens the transfer of displacement between soft linked fault segments is characterized by well de fined dipping relay ramps commonly rotated and extended to accommodate the ductile strain between the overlapping fault segments relay ramps develop as ephemeral structures eventually becoming breached by hard linkage of the fault segments breakdown of ramps by breaching is part of the process of fault growth by segment linkage within the canyonlands graben system four orders of segmentation are present this may be a consequence of different scales of mechanical heterogeneity but evidence from the canyonlands grabens and elsewhere points to a fundamental process of discontinuous fault growth by segment linkage

normal fault growth and fault related folding in a salt influenced rift basin south viking graben offshore norway abstract three dimensional seismic data were analysed to reconstruct the structural and stratigraphical development of a salt influenced rift basin and thus gain an understanding of the relationships between normal fault growth salt tectonics and the evolution of syn rift depocentres the sleipner basin south viking graben northern north sea is ca 30 km long by 8 km wide and is bound to the east by a major extensional fault zone sleipner fault zone two types of fault related fold are identified within the basin 1 a fault parallel monocline interpreted as an extensional forced fold which formed through the upward propagation of the sleipner fault zone through ductile evaporites of the zechstein supergroup and 2 three fault perpendicular salt cored anticlines that compartmentalise the basin into four sub basins and are related to displacement gradients along strike of the sleipner fault zone detailed seismic stratigraphic analysis of pre and syn rift stratal units reveals a complex interplay between fault growth and salt movement which strongly controlled the evolution of syn rift depocentres during the early syn rift a series of depocentres separated along strike by the fault perpendicular folds were offset into the axis of the basin ca 3 4 5 km to the west of the sleipner fault zone by the fault propagation fold later in the rift event the influence of the fault perpendicular folds depleted resulting in a larger interconnected depocentre that shifted into the immediate hangingwall of the fault as the surface of the fault propagation fold was breached the results of this study have implications for normal fault growth and sedimentary depocentre development in salt influenced rift basins and contribute to the general understanding of the controls on salt migration

high frequency turbulence and suspended sediment concentration measurements in the garonne river tidal bore the study details new sediment concentration measurements associated with some turbulence characterisation conducted at high frequency in the undular tidal bore of the garonne river france acoustic doppler velocimetry was used and the suspended sediment concentration was deduced from the acoustic backscatter intensity the field data set demonstrated some unique flow features of the tidal bore including some large and rapid turbulent velocity fluctuations during and after the bore passage some unusually high suspended sediment concentration was observed about 100 s after the tidal bore front lasting for more than 10 min it is thought that the tidal bore passage scoured the bed and convected upwards the bed material reaching the free surface after the bore passage behind the tidal bore the net sediment flux magnitude was 30 times larger than the ebb tide net flux and directed upstream a striking feature of the data set was the intense mixing and suspended sediment motion during the tidal bore and following flood tide this feature has been rarely documented

selective reverse reactivation of normal faults and deformation around reverse reactivated faults in the mesozoic of the somerset coast abstract normal faults exposed in the triassic jurassic limestones and shales of the somerset coast were formed during the mesozoic development of the bristol channel basin reverse reactivation of some of these normal faults occurred during late cretaceous to early tertiary north south contraction the contraction is also evident from thrusts and conjugate strike slip faults preferential reactivation of the normal faults is attributed to 1 decreased fault plane friction 2 domino block rotation 3 displacement magnitude and 4 fault connectivity the geometries of overlapping and underlapping zones in reactivated fault zones are dependent on the existing structural geometry two distinctive styles of displacement accommodation occur between reverse reactivated normal faults 1 formation of a network of strike slip faults conjugate about nne ssw and 2 oblique steeply dipping reverse faults interaction between strike slip and an existing fault is dependent on whether the normal fault was reactivated the range of structures related to the north south contraction has been incorporated into a single deformation model controlled by the northwards movement of the hanging wall of the quantock s head fault pure dip slip movement occurred in the centre of its curved fault trace with a sinistral component at the western tip and a dextral component of displacement and strike slip block rotations occurred at the eastern tip shortening of these blocks was achieved through development of a strike slip fault network and nw striking thrusts in an underlap zone loading of the footwall by the hanging wall block modified the local stress system to allow formation of oblique steeply dipping reverse faults

exploring the use of alternative groundwater models to understand the hydrogeological flow processes in an alluvial context tiber river rome italy the first step of the application of a groundwater model to a specific site is the identification of the conceptual model in this paper a methodology to compare different conceptual models is proposed such a method consists in the parallel run of simple groundwater models based on different conceptual models and in the evaluation of each model fitting the case study proposed to illustrate this approach belongs to the alluvial series of the tiber river rome italy

lateral variability of subtidal flow at the mid reaches of a macrotidal estuary transverse variations of tidal and subtidal flow were investigated in a macrotidal and convergent estuary this was accomplished by combining data analysis of current velocities and water density with numerical modeling at the mid reaches of the gironde estuary france nonlinear mechanisms responsible for overtide generation and hence subtidal flows were found to vary across the estuary and from neap to spring tides subtidal flows were driven by a combination of internal asymmetry tidal advective accelerations nonlinear effects of water level variations quadratic friction and river discharge the quarter diurnal overtide band d4 in the flow was generated by internal asymmetry and tidal advective accelerations during neap tide the ratio of quarter diurnal to squared semidiurnal bands d4 d22 was largest 0 3 in sections of the channel showing subtidal outflow river discharge increased from neap to spring tides causing a subsequent increase of seaward subtidal currents during spring tide d4 was generated by tidal advective accelerations and quadratic friction combined with river discharge rather than by internal asymmetry the sixth diurnal overtide d6 in the flow was comparable to d4 for both neap and spring tides largest d6 d23 ratios were found in the shallowest cross channel locations during both neap and spring tides

late cretaceous and cenozoic intra plate compressional deformations in the alpine foreland a geodynamic model abstract the mesozoic grabens and wrench induced troughs of western and central europe developed in response to triassic early cretaceous intra plate tensional stresses which affected the arctic north atlantic and the tethys borderlands during the rifting phase preceding the opening of the respective oceans this resulted in the fragmentation of the continental crust of the alpine foreland during the late cretaceous and tertiary alpine orogeny collision related compressive stresses exerted on the foreland induced the reactivation of these fracture systems causing the inversion of mesozoic grabens and the uplifting of major basement blocks at distances up to 1300 km to the north of the present alpine deformation front the structural style of these inverted basins and basement uplifts is indicative of compressional and transpressional deformations the total amount of crustal shortening associated with these deformations is unlikely to exceed a few tens of kilometres these displacements require a coupling between the foreland and the orogen at the alpine a subduction zones and within the foreland a decoupling at intra crustal levels between the crust and mantle and or at deeper lithospheric levels the example of the alpine foreland indicates that compressive stresses inducing major deformations can be transmitted from a collisional plate boundary through continental lithosphere over distances of up to 1300 km circumstantial evidence suggests that collision related compressive stresses not large enough to give rise to significant deformations can be transmitted through continental lithosphere over even greater distances

structural style and early stage growth of inversion structures 3d seismic insights from the egersund basin offshore norway abstract high quality three dimensional 3d seismic reflection and borehole data from the egersund basin offshore norway are used to characterise the structural style and determine the timing of growth of inversion related anticlines adjacent to a segmented normal fault system two thick skinned normal faults which offset permian clastics and evaporites delineate the north eastern margin of the basin these faults strike nnw sse have up to 1900 m of displacement and are separated by an ese dipping c 10 km wide relay ramp both of these faults display exclusively normal separation at all structural levels and tip out upwards into the upper part of the lower cretaceous succession at relatively shallow structural levels in the hangingwalls of these faults a series of open low amplitude fault parallel anticlines are developed these anticlines which are asymmetric and verge towards the footwalls of the adjacent faults are interpreted to have formed in response to mild inversion of the egersund basin the amplitude of and apparent shortening associated with the anticlines vary along strike and these variations mimic the along strike variations in throw observed on the adjacent fault segments we suggest that this relationship can be explained by along strike changes in the propensity of the normal faults to reactivate during shortening wider damage zones and lower angles of internal friction coupled with higher pore fluids pressures at the fault centre mean that reactivation is easier at this location than at the fault tips or in the undeformed country rock seismic stratigraphic analysis of growth strata indicate that the folds initiated in the latest turonian to earliest coniacian c 88 6 ma and santonian c 82 6 ma the control on this c 6 myr diachroneity in the initiation of fold growth is not clear but it may be related to strain partitioning during the early stages of shortening anticline growth ceased in the maastrichtian and the inversion event is therefore interpreted to have lasted at least c 20 myr this study indicates that 3d seismic reflection data is a key tool to investigate the role that normal fault segmentation can play in controlling the structural style and timing of inversion in sedimentary basins furthermore our results highlight the impact that this structural style variability may have on the development of structural and stratigraphic hydrocarbon traps in weakly inverted rifts

a new analytical framework for assessing the effect of sea level rise and dredging on tidal damping in estuaries this paper explores different analytical solutions of the tidal hydraulic equations in convergent estuaries linear and quasi nonlinear models are compared for given geometry friction and tidal amplitude at the seaward boundary proposing a common theoretical framework and showing that the main difference between the examined models lies in the treatment of the friction term a general solution procedure is proposed for the set of governing analytical equations expressed in dimensionless form and a new analytical expression for the tidal damping is derived as a weighted average of two solutions characterized by the usual linearized formulation and the quasi nonlinear lagrangean treatment of the friction term the different analytical solutions are tested against fully nonlinear numerical results for a wide range of parameters and compared with observations in the scheldt estuary overall the new method compares best with the numerical solution and field data the new accurate relationship for the tidal damping is then exploited for a classification of estuaries based on the distance of the tidally averaged depth from the ideal depth relative to vanishing amplification and the critical depth condition for maximum amplification finally the new model is used to investigate the effect of depth variations on the tidal dynamics in 23 real estuaries highlighting the usefulness of the analytical method to assess the influence of human interventions e g by dredging and global sea level rise on the estuarine environment

facies associations detrital clay grain coats and mineralogical characterization of the gironde estuary tidal bars a modern analogue for deeply buried estuarine sandstone reservoirs abstract estuarine tidal bar sandstones are complex reservoir geobodies commonly exploited by the oil and gas industry in order to better predict the reservoir potential of these geobodies this study provides a modern day reservoir analogue describing tidal bars in the inner and outer gironde estuary from the microscopic to the macroscopic scale the originality of this work lies in the multi scale study of modern estuarine tidal bars based on numerous piston cores extracted in a high energy environment this work demonstrates that these tidal bars are composite sedimentary bodies made up of individual reservoir sand units separated by thick muddy layers their vertical facies associations and internal architectures are controlled by local hydrodynamic variations and seasonal river influxes detrital clay grain coats are notably characterized using a portable and handheld mineral spectrometer from the base to the top of the tidal bars x ray diffraction and electron microscopes reveal that these coats are mainly composed of di octahedral smectite illite chlorite and kaolinite associated with other components such as diatoms or pyrite the best reservoir geobodies are those with the minimum clay permeability barriers at the macro and mesoscale an optimum coated grain content and clay fraction volume is also needed for generating authigenic clay coatings and inhibiting quartz overgrowth these conditions are met within the tidal sand bars of the outer estuary funnel that are expected to be the best reservoir geobodies in deeply buried sandstones

influence of a transverse basement fault on along strike variations in the geometry of an inverted normal fault case study of the mosha fault central alborz range iran abstract inverted normal faults show variations in structural geometry from footwall shortcut thrusts to hanging wall break back thrusts in the present study we evaluated along strike variations in the geometry of the mosha fault central alborz range iran detailed structural mapping within the taleqan mountains revealed that the mosha fault in the eastern part of the study area is associated with a large basement cored hanging wall anticline thrust over tertiary rocks that occur as a syncline or cut by footwall shortcut thrusts in the western part of the study area however the hanging wall consists of break back thrust sheets of paleozoic mesozoic rocks these thrust sheets occur as a duplex system and have allochthonous masses gravitationally emplaced in the foothills of the taleqan mountains curved fold axial traces and scattered intrusive bodies are observed in the valian valley area where the mosha fault is displaced across a transverse basement fault this basement fault controlled along strike variations in the geometry of the mosha fault during its evolution from a basin bounding fault to an inverted normal fault inversion of the fault in the eastern part of the study area where the fault is relatively steep involved basement rocks in the western part of the study area where the fault is relatively shallowly dipping deformation in the hanging wall is accommodated by thin skinned break back thrust sheets

static and dynamic characterization of alluvial deposits in the tiber river valley new data for assessing potential ground motion in the city of rome 1 the paper presents the results of a case study conducted on the holocene alluvial deposits of the tiber river valley in the city of rome the main test site selected for the study valco s paolo is located about 2 km south of rome s historical centre the alluvial deposits were dynamically characterized in a comprehensive way via site investigations and geotechnical laboratory tests normalized shear modulus decay and damping curves g g0 and d d0 vs were obtained for the dominantly fine grained levels the curves demonstrate that these levels have a more marked shear stiffness decay if compared with the underlying pliocene bedrock decay curves from laboratory tests for the tiber alluvia correlated well with the trend of the function proposed by hardin and drnevich making it possible to derive their specific interpolation function coefficients use was made of the extrapolation of the findings from the valco s paolo test site to a large part of rome s historical centre by means of two other test sites supported by an engineering geology model of the complex spatial distribution of the tiber alluvia the experimental valco s paolo vs profile was extrapolated to the other test sites on the basis of a stratigraphic criterion the analysis of seismic noise measurements obtained for the three test sites validated the engineering geology based extrapolation and showed that the main rigidity contrast occurs inside the alluvial body at the contact with the underlying basal gravel level g and not between the alluvia and the plio pleistocene bedrock composed of highly consistent clay marne vaticane the 1d modeling of local seismic response to the maximum expected earthquakes in the city of rome confirms that the deposits have one principal mode of vibration at about 1 hz however the simulation also evidenced that the silty clay deposits level c making up the most part of the tiber alluvial body play a key role in characterizing the soil column deformation profile since it can be affected by non linear effects induced by the maximum expected earthquake when some stratigraphic conditions are satisfied

surface electrical resistivity tomography and hydrogeological characterization to constrain groundwater flow modeling in an agricultural field site near ferrara italy a portion of an unconfined alluvial aquifer located in the padana plain italy was characterized following an integrated hydro geophysical approach initially an electrical resistivity tomography ert survey was employed to localize the boundaries of a modest paleo channel body and to design the installation of a groundwater monitoring network multilevel slug tests were performed to estimate the aquifer s saturated hydraulic conductivities determined permeability values together with electrical resistivity data were correlated the correlation resulted in a site specific bi logarithmic linear relationship based on this relationship punctually determined hydraulic conductivities were spatially extended over the studied flow domain finally continuously measured piezometric heads were used to calibrate a 3d flow model sensitivity analysis was performed to confirm the reliability of the reconstructed permeability field as well as to assess the minimum number of direct measurements needed to safely characterize the selected aquifer portion the integration of the ert survey results with the classical hydrogeological tests can be conveniently applied to constrain the permeability field during flow model calibration although the applicability of the determined relationship is site specific the followed procedure is useful especially when there is a need to optimize the available resources and in case of small scale pilot studies

modelling hydrostratigraphy and groundwater flow of a fractured and karst aquifer in a mediterranean basin salento peninsula southeastern italy the control exerted by the hydrostratigraphic structure on aquifer recharge groundwater flow and discharge along the coastal areas of a mediterranean basin salento peninsula about 5 000 km2 wide southern italy is assessed through the development and application of a groundwater flow model based on the reconstruction of the hydrostratigraphic architecture at the regional scale the hydrostratigraphic model obtained by processing surface and subsurface data is applied to map the top of the main aquifer which is hosted in the deep hydrostratigraphic unit corresponding to cretaceous and oligocene limestones with complex geometrical relationships with the sea it is also used to estimate the aquifer recharge which occurs by percolation through overlying younger sediments with low permeability these data are completed with information about the soil use to estimate water abstraction for irrigation and with literature data to estimate the water abstraction for drinking and industrial purposes the above sketched conceptual model is the basis for a finite difference groundwater 2d pseudo stationary flow model which assumes the following fundamental approximations the fractured and karst limestone hydrostratigraphic unit can be approximated at the model scale as a continuous medium for which the discrete darcy s law is valid the transition zone between salt and fresh water is so small with respect to the grid spacing that the ghyben herzberg s approximation for a sharp interface can be applied along the coastline different boundary conditions are assigned if the top of the limestone hydrostratigraphic unit lies either above the sea level the aquifer has a free surface and fresh water is drained or below the sea level the aquifer is under pressure and the contact with sea occurs off shore the groundwater flow model correctly predicts the areas where the aquifer is fully saturated with salt water

cohesive strengthening of fault zones during the interseismic period an experimental study 1 there is widespread evidence indicating that faults regain a portion of their strength during the interseismic period here we present experiments designed to understand and quantify the interseismic cohesive strengthening resulting from fluid rock reactions in fault zones the triaxial experiments consisted of fracturing cores of fontainebleau sandstone under dry conditions forming a localized shear failure zone stage 1 the specimens were then reacted hydrothermally under isostatic conditions allowing the fault damage zone to compact consolidate and strengthen stage 2 following reaction the specimens were then reloaded to failure under nominally dry conditions so that the increase in cohesive strength of the fault could be measured stage 3 experiments show that cohesion increase is positively correlated to temperature and pore pressure during reaction after 6 hours of reaction at the highest temperatures 927 c and pore pressures 200 mpa cohesion increases by as much as 35 mpa microstructural examination of the specimens showed that the gouge particles within the fault compacted and cemented together exhibiting textures typical of pressure solution and that fractures in the surrounding damage zone had healed a theoretical treatment of the data was conducted using these experiments in combination with results on time dependent changes in fault cohesion presented by tenthorey et al 2003 we find that the rate controlling process in our experiments has an activation energy q of approximately 70 kj mol 1 we use this information to develop a model for time dependent cohesive strengthening in fault zones within the continental seismogenic regime we conclude that significant cohesive strengthening of fault zones can occur during the interseismic period of medium to large earthquakes given the presence of reactive pore fluids

simulation of groundwater dynamic response to hydrological factors in karst aquifer system abstract a similar physical simulation experiment is a kind of generalization and reduction of real objects by similarity principle which achieves the simulation of the actual situation in order to reveal the influencing factors and mechanisms of the groundwater flow process in the karst aquifer system in this paper the hydrological cycle process of the karst aquifer system is comprehensively considered and a conceptual model is established including hydrological factors such as rainfall recharge epikarst zone doline fissure conduit and spring also a three dimensional physical model of karst fissure conduit for experiments is designed and fabricated from the similarity with the groundwater channel structure based on the hydrological conceptual model moreover karst aquifer under different rainfall conditions and aquifer structures is designed to simulate the process of seepage and recession the experiments were divided into 24 groups three times for each group the experiment results show that 1 the rainfall intensity has a significant impact on the maximum peak flow confluence time and flow duration of the spring flow process 2 the epikarst zone has a vital influence on the confluence time flow duration and curve shape of the spring flow process and has little effect on the peak flow and 3 the aquifer structure is the main factor affecting the initial flow the slope of the recession curve and the recession coefficient of the spring recession process finally this study indicates that the concept model is reasonable the physical model for simulating the hydrological process can be applied to a wide range in karst aquifers taking into account more geological factors

wind induced salt wedge intrusion in the tiber river mouth rome central italy the wind effect on river water quality was illustrated by means of thermohaline measurements carried out in the tiber river in may 2012 the survey was carried out using a boat in stations located in the two tiber branches fiumara grande and traiano canal thermohaline variables salinity and temperature were used to describe the water type patterns and to define the salt wedge position although the river flow rate was rather high saltwater intrusion happened wind data suggested that the more probable cause of salt wedge intrusion was the wind action especially wind speeds higher than 4 m s are able to dominate the sea current at surface layers determining an increase in the sea level therefore westerly winds determined a seawater inflow in the river mouths

sandbox experiments on basin inversion testing the influence of basin orientation and basin fill analogue modelling experiments using brittle materials are performed to study the inversion of extensional structures asymmetric grabens of two different orientations are first created during a phase of extension and progressively filled they are subsequently shortened in the same direction the aim of our experiments is to determine factors affecting the style of deformation during inversion we specifically investigate variations in thickness and distribution of strong and weak layers constituting the graben fill and in initial basin orientation the main advantage of our experimental set up is that we have a complete control on graben location width infill and orientation before inversion the experiments show that shortening results only in limited reactivation of pre existing normal faults in general forward thrusts and backthrusts cut across normal faults into the footwall of the graben the forward thrusts either propagate parallel to the enveloping surface of faulted blocks or they cut across basin limiting normal faults at various angles the graben fill is mechanically extruded by displacement along forward thrusts that accommodate most of the shortening both pre existing faults and weak graben fill act as zones of weakness during inversion and determine the orientation and location of both backthrusts and forward thrusts the results of our experiments conform well to natural examples of inverted graben structures

human induced seismicity and large scale hydrocarbon production in the usa and canada we compare current and historic seismicity rates in six states in the usa and three provinces in canada to past and present hydrocarbon production all states provinces are major hydrocarbon producers our analyses span three to five decades depending on data availability total hydrocarbon production has significantly increased in the past few years in these regions increased production in most areas is due to large scale hydraulic fracturing and thus underground fluid injection furthermore increased hydrocarbon production generally leads to increased water production which must be treated recycled or disposed of underground increased fluid injection enhances the likelihood of fault reactivation which may affect current seismicity rates we find that increased seismicity in oklahoma likely due to salt water disposal has an 85 correlation with oil production yet the other areas do not display state province wide correlations between increased seismicity and production despite 8 16 fold increases in production in some states however in various cases seismicity has locally increased multiple factors play an important role in determining the likelihood of anthropogenic activities influencing earthquake rates including i the near surface tectonic background rate ii the existence of critically stressed and favorably oriented faults which must be hydraulically connected to injection wells iii the orientation and magnitudes of the in situ stress field combined with iv the injection volumes and implemented depletion strategies a comparison with the seismic hazard maps for the usa and canada shows that induced seismicity is less likely in areas with a lower hazard the opposite however is not necessarily true

dynamic triggering of microseismicity in a mine setting summary seismicity is correlated in space and time with mining activities we initially expected blasting operations to trigger events however no seismicity is detected during the two to three hours after each blast one possibility is that seismicity is triggered due to subsidence assuming a compacting earth surprisingly the seismicity occurs during certain times during the day therefore it is likely that the seismic activity has been triggered by the transportation of the debris along the shaft and main tunnels this analysis can enhance our understanding of activation processes and factors that can severely impact the safety and productivity of the mine

successive impact of tidal bores on sedimentary processes arcins channel garonne river a tidal bore is a hydrodynamic shock propagating upstream as the tidal flow turns to rising with macro tidal conditions in a funnel shaped system with shallow waters the tidal bore of the garonne river was extensively investigated in the arcins channel between 2010 and 2013 typically over one to two days in 2015 new field measurements were repeated systematically at the same site on 29 august 1 september 2015 and on 27 october 2015 the nature of the observations was comprehensive encompassing hydrodynamics and turbulence as well as sediment properties and transport the tidal bore occurrence had a marked effect on the velocity and suspended sediment field including a rapid flow deceleration and flow reversal during the bore passage with very large suspended sediment concentrations sscs during the passage of the tidal bore front and early flood tide as well as very large suspended sediment flux during the very early flood tide the suspended sediment concentration ssc data indicated a gradual increase in initial mean ssc estimate prior to the bore from 29 august to 1 september 2015 a comparison between suspended sediment flux data showed very significant suspended sediment flux on the first day of tidal bore occurrence with a decreasing magnitude over the next three days the data suggested a two stage bed scour process at each tidal bore event surface erosion occurred initially in the form of stripping the first stage was followed by delayed mass erosion occurring about 5 15 min after the tidal bore

sedimentary basin inversion and intra plate shortening abstract sedimentary basin inversion the shortening of formerly extensional basins is accommodated mainly by compressional reactivation of extant faults and fractures across a wide range of scales as such inversion is a large scale manifestation of byerlee friction the dynamic criterion for fault reactivation governing the effective shear strength of the shallow crust basin inversion generates distinctive deformational architecture and it is implicated strongly in sedimentary basin exhumation as a principal source of horizontal stress inversion drives significant sedimentary porosity reduction and resultant fluid flow upper crustal deformation is critically dependent on fluid overpressure i e pore fluid pressures greater than would be calculated from a hydrostatic gradient and perhaps more than in any other tectonic setting overpressures are potentially large during sedimentary basin inversion this review therefore includes discussion of the role of fluid overpressure in inversion and the evidence for it collectively inversion has profound implications good and bad for the prospectivity of many petroliferous sedimentary basins thus recognizing the evidence for basin inversion quantifying its magnitude and understanding the mechanisms that accommodate inversion and other phenomena affected by it have become essential components of the basin analyst s remit

meteotsunami marrobbio of 25 26 june 2014 on the southwestern coast of sicily italy a major tsunami like event locally known as marrobbio impacted the southwestern coast of sicily on 25 26 june 2014 the event was part of a chain of hazardous episodes in the mediterranean and black seas during the last week of june 2014 resulting from an anomalous atmospheric system tumultuous atmosphere propagating eastward over the region the synoptic patterns and vertical structure of the atmosphere over sicily at the time of the event indicate that atmospheric wave ducting was responsible for the generation of tsunamigenic air pressure disturbances that produced especially high sea level responses meteotsunamis at certain sites along the sicilian coast the strongest sea level oscillations were observed at mazara del vallo where a 1 m meteotsunami bore propagating upstream in the mazaro river was generated the combined effects of external resonance proudman resonance on the western sicilian shelf and internal resonant conditions bathymetric and topographic characteristics of specific sites were found to be the key factors that caused the meteotsunami marrobbio phenomenon on the coast of sicily and the meteobore at mazara del vallo

tidal bore dynamics in funnel shaped estuaries the formation and dynamics of tidal bores in funnel shaped estuaries is investigated from both a global tidal wave scaling analysis and new quantitative field observations we show that tidal bore occurrence in convergent estuaries can be estimated from a dimensionless scaling parameter characterizing the relative intensity of nonlinear friction versus local inertia in the momentum equation a detailed analysis of tidal bore formation and secondary wave structure is presented from a unique long term database observations of more than 200 tides acquired during four campaigns in the two main french tidal bore estuaries the seine and gironde garonne estuaries we describe the effect of freshwater discharge on the global tidal wave transformation at the estuarine scale and on local tidal bore occurrence in the upper estuary our field data suggest that the tidal bore intensity is mainly governed by the dimensionless tidal range which characterizes the local tidal wave nonlinearity we also show that the secondary wavefield associated with tidal bore propagating in natural estuaries differs significantly from those associated to undular bores in rectangular channels in particular we observe an abrupt decrease of the whelp steepness when the froude number goes below 1 1 this secondary field transition can explain why tidal bore occurrence in worldwide estuaries is certainly underestimated

geotechnical studies for foundation settlement in holocenic alluvial deposits in the city of rome italy abstract this study identifies units characterized by specific geomechanical behaviours within some holocene alluvial deposits in the city of rome in particular the highly compressible units which may be responsible for subsidence and settlement phenomena below urban structures have been identified investigations carried out during this study have interpreted nearly 800 stratigraphic sections and physical mechanical features of the alluvial deposits of the tiber and those of its right and left bank tributaries the analysis allowed to define for each investigated deposit a representative series subdivided into lithotechnical units when comparing the stratigraphic and geologic features among the series a remarkable difference in geomechanical behaviour in the deposits from the tiber s left and right bank tributaries and within the river s deposits themselves could be recognized a yield hazard zoning for urban structures related to recent alluvial deposits has also been defined

analytical description of tidal dynamics in convergent estuaries analytical solutions of the one dimensional hydrodynamic equations for tidal wave propagation are now available and in this paper presented in explicit equations for given topography friction and tidal amplitude at the downstream boundary the velocity amplitude the wave celerity the tidal damping and the phase lag can be computed the solution is based on the full nonlinearized st venant equations applied to an exponentially converging channel which may have a bottom slope two families of solutions exist the first family consists of mixed tidal waves which have a phase lag between zero and 2 which occur in alluvial coastal plain estuaries with almost no bottom slope the second family consists of apparent standing waves which develop in short estuaries with a steep topography asymptotic solutions are presented for progressive waves frictionless waves waves in channels with constant cross section and waves in ideal estuaries where there is no damping or amplification the analytical method is accurate in the downstream marine part of estuaries and particularly useful in combination with ecological or salt intrusion models the solutions are compared with observations in the schelde elbe and mekong estuaries

chalk fields along the lindesnes ridge eldfisk abstract eldfisk field lies on the lindesnes ridge northwest of the valhall and hod fields and to the southeast of edda in block 2 7 of the norwegian north sea the field has a complex geological history and reservoir geometry seismic reflection data is strongly gas affected and degraded over the majority of the field the geological model of the field was based exclusively on well data and the model was inadequate to explain some of the production characteristics or to identify additional prospective well locations in 1982 a programme of vertical seismic profiling vsp was started in the northern part of the field the seismic data provided by vsp have improved and confirmed the geological model provided some explanations for production variances and identified further areas of interest

undular tidal bore dynamics in the daly estuary northern australia measurements in the macro tidal daly estuary show that the presence of an undular tidal bore contributed negligibly to the dissipation of tidal energy no recirculation bubble was observed between a trough and the following wave crest in the lee waves following the undular bore this differs to stationary undular bores in laboratory experiments at larger froude numbers where a recirculation bubble exists secondary motions and the turbulence generated by the undular bore had no measurable influence on the sediment transport this situation contrasts with the intense sediment resuspension observed in breaking tidal bores the tidally averaged sediment budget in the daly estuary was controlled by the asymmetry of tidal currents the undular bore may widen the river by breaking along the banks that it undercuts leading to bank slippage a patch of river wide macro turbulence of 3 min duration occurred about 20 min after the passage of the bore during accelerating tidal currents

conditions for tidal bore formation in convergent alluvial estuaries abstract over the last decade there has been an increasing interest in tidal bore dynamics however most studies have been focused on small scale bore processes the present paper describes the first quantitative study at the estuary scale of the conditions for tidal bore formation in convergent alluvial estuaries when freshwater discharge and large scale spatial variations of the estuary water depth can be neglected tide propagation in such estuaries is controlled by three main dimensionless parameters the nonlinearity parameter e 0 the convergence ratio 0 and the friction parameter 0 in this paper we explore this dimensionless parameter space in terms of tidal bore occurrence from a database of 21 estuaries 8 tidal bore estuaries and 13 non tidal bore estuaries the field data point out that tidal bores occur for convergence ratios close to the critical convergence c a new proposed definition of the friction parameter highlights a clear separation on the parameter plane 0 e 0 between tidal bore estuaries and non tidal bore estuaries more specifically we have established that tidal bores occur in convergent estuaries when the nonlinearity parameter is greater than a critical value e c which is an increasing function of the friction parameter 0 this result has been confirmed by numerical simulations of the two dimensional saint venant equations the real estuary observations and the numerical simulations also show that contrary to what is generally assumed tide amplification is not a necessary condition for tidal bore formation the effect of freshwater discharge on tidal bore occurrence has been analyzed from the database acquired during three long term campaigns carried out on the gironde garonne estuary we have shown that in the upper estuary the tidal bore intensity is mainly governed by the local dimensionless tide amplitude e the bore intensity is an increasing function of e and this relationship does not depend on freshwater discharge however freshwater discharge damps the tidal wave during its propagation and thus reduces e and consequently limits the tidal bore development in the estuary to take into account this process in the tidal bore scaling analysis it is necessary to introduce a fourth external parameter the dimensionless river discharge q 0

basin inversion and fault reactivation in laboratory experiments abstract a series of analogue models have been performed to get insights into the relationships between the reactivation of pre existing normal faults and the orientation of a successive compressive stress field the models were deformed in two phases 1 a first extension phase h 3 generating a graben and 2 a successive compressive phase with the orientation of the shortening direction h 1 trending between 0 and 90 obliquity angle to the faults bounding the graben the deepening of this graben was accompanied by syn tectonic sedimentation that included a basal ductile layer simulating salt in nature overlain by a brittle sand pack the experimental results suggest that the development of compressive structures is strongly controlled by the pre existing normal faults and by the obliquity angle the experiments have invariably shown that the extensional faults were reactivated during shortening whatever the value of the angle whereas strike slip reactivation of major normal faults is favoured by low obliquity angles mostly dip slip reactivation of pre existing structures is instead promoted for high obliquity angles the analysis of model results highlights the important role played by a ductile layer at the base of the basin fill and the obliquity angle in controlling both strain partitioning and brittle ductile decoupling

recovering water wave elevation from pressure measurements the reconstruction of water wave elevation from bottom pressure measurements is an important issue for coastal applications but corresponds to a difficult mathematical problem in this paper we present the derivation of a method which allows the elevation reconstruction of water waves in intermediate and shallow waters from comparisons with numerical euler solutions and wave tank experiments we show that our nonlinear method provides much better results for the surface elevation reconstruction compared to the linear transfer function approach commonly used in coastal applications more specifically our method accurately reproduces the peaked and skewed shape of nonlinear wave fields therefore it is particularly relevant for applications on extreme waves and wave induced sediment transport

application of geometric models to inverted listric fault systems in sandbox experiments paper 1 2d hanging wall deformation and section restoration abstract fault geometry is a primary control on hanging wall deformation in order to examine their geometrical relationships a positive inversion analogue experiment was conducted using a rigid fault surface of listric geometry the hanging wall deformation observed on a representative vertical section was examined with conventional 2d geometric models and was restored to its pre inversion phase with two techniques these results suggest that the deformation can be best approximated by inclined simple shearing iss the iss model can determine the inclination of the apparent shear plane and the amount of apparent horizontal shortening which is equivalent to that calculated with the conventional depth to detachment method this estimated apparent shortening was generally smaller than the actual amount of the experiments probably due to tectonic compaction

influence of preexisting fault fabric on inversion related deformation a case study of the inverted fundy rift basin southeastern canada 1 preexisting zones of weakness significantly influenced the structural development of the fundy basin during rifting and subsequent basin inversion the preexisting fabric consisting of ne striking faults with gentle dips and east striking faults with steeply dipping upper segments and gently dipping lower segments formed during paleozoic and older orogenic activity during mesozoic rifting the preexisting fabric was reactivated creating a border fault system composed of linked ne and east striking extensional fault zones with anomalous dips gentle and steep compared to those of newly formed normal faults during inversion the preexisting fabric was again reactivated as the hanging wall of the composite border fault system moved nne relative to the footwall inversion was highly oblique on the ne striking fault zones producing gentle fault parallel buttress folds and fault perpendicular detachment folds above the low angle fault zones inversion was moderately oblique on the east striking fault zone producing relatively tight fault parallel buttress and detachment folds above the gently dipping lower fault segments and reactivating the steeply dipping upper fault segments as left lateral strike slip faults thus inversion related deformation on the east striking fault zone was partitioned at shallow levels i e partitioned updip our work shows that the geometry of preexisting extensional faults and their obliquity relative to the shortening direction profoundly affect deformation style during basin inversion namely the type of inversion related faults the type and shape of inversion related folds and the distribution of deformation e g updip partitioning depend in part on the geometry of the preexisting extensional faults and the variations in these geometries with depth and along strike