the propagation of internal solitary waves over variable topography in a horizontally two dimensional framework abstractthis paper presents a horizontally two dimensional theory based on a variable coefficient kadomtsev petviashvili equation which is developed to investigate oceanic internal solitary waves propagating over variable bathymetry for general background density stratification and current shear to illustrate the theory a typical monthly averaged density stratification is used for the propagation of an internal solitary wave over either a submarine canyon or a submarine plateau the evolution is essentially determined by two components nonlinear effects in the main propagation direction and the diffraction modulation effects in the transverse direction when the initial solitary wave is located in a narrow area the consequent spreading effects are dominant resulting in a wave field largely manifested by a significant diminution of the leading waves together with some trailing shelves of the opposite polarity on the other hand if the initial solitary wave is uniform in the transverse direction t

inferences on active faults at the southern alps liguria basin junction from accurate analysis of low energy seismicity abstract seismotectonic studies concern themselves with understanding the distribution of earthquakes in space time size and style therefore the better these parameters are known the most correct the association of any seismic event with the faulting structure that caused it will result the use of accurate location methods is especially required when dealing with very complex areas where several faulting systems or relatively small seismogenic structures exist in fact even though routinely determined epicentres are capable of revealing the rough picture of the seismicity they are not suitable for studies of the fine structure of the causative fault as their location uncertainties are often larger than the source dimension itself in this work the probabilistic approach of the non linear localization has been used to compute precise locations for earthquakes occurred in the last twenty years nearby the saorge taggia line a complex fault system situated in western liguria close to the border between italy and france together with the breil sospel monaco and the peille laghet faults this line is responsible for the seismic activity of the area the seismotectonic study is completed through a local tomographic study and the analysis of the focal mechanisms computed for an enlarged area the results show that the seismicity associated with this fault system is confined within the first 10 km depth many clusters of seismic events are identified along the saorge taggia line the existence of a not previously mapped branch perpendicular to the saorge taggia line is also recognized although its position may suggest it to be the continuation of the breil sospel monaco fault system towards ne our finding would rather suggest no association with the fault the overall results confirm the complexity of the area in particular the hypothesis that the saorge taggia system may represent the eastward limit of a subalpine crustal block comprised within the nice arc the named fault and a thrust front which is supposed to be located 20 km offshore find a confirm in the shallow depth of the seismic events in addition we propose that the western limit of the block located along the nice arc could be instead shifted where the peille laghet fault lays

states of paleostress north and south of the periadriatic fault comparison of the drau range and the friuli southalpine wedge this study focuses on the analysis of structures and kinematics of a n s profile along the axis of maximum shortening of the european eastern alps the area includes the southern austroalpine unit in the north and the southalpine unit which is a part of the adriatic indenter the stratigraphically different units are separated by the periadriatic fault the major strike slip fault within the alps in order to assess the kinematics of these units mainly fault slip data from north and south of the periadriatic fault were analyzed we distinguish a succession of five main kinematic groups in both units 1 n s compression 2 nw se compression 3 ne sw compression 3 changes gradually from subvertical to subhorizontal 4 n s compression and 5 nw se compression our study reveals that the deformation sequence on either sides of the paf is similar the mean orientations of the principal stress axes however show small but consistent differences the subhorizontal axes north of the periadriatic fault plunge northward in the south southward a counterclockwise ccw rotation of the southern part in respect to the north is evident and in line with the well known counterclockwise rotation of the adriatic indenter as well as dextral displacement of the n fanning stress field along the periadriatic fault opposing plunge directions are interpreted as a primary feature of the internal stress field within an orogenic wedge further increased during ongoing compression

simple model for the recirculation velocity of open channel embayments abstracta simple theoretical model is presented in order to predict the recirculation velocity in river embayments also commonly referred to as eddies gyres cavities and dead zones this velocity is important as it sets the fundamental timescale of the motion in these ecologically important regions using only an equilibrium torque balance basic geometrical properties and resistance characteristics the eddy velocity is determined as a percentage of the freestream velocity the model is restricted to the single gyre case placing modest limits on the embayment aspect ratio the result compares favorably with recent experimental computational and field studies of river embayments

intrinsic and scattering seismic wave attenuation in the central apennines italy abstract recently an earthquake sequence formed by a series of subsequences characterized by large earthquakes three events m 6 0 and five events m 5 0 occurred in the central apennines in 6 7 months during 2016 2017 several studies interpreted this cascading type of earthquake occurrence as associated with fluid movements through an interconnected network of cracks around the active faults that triggered the subsequences in different time and location in the present study we aim to verify if the presence of fluids is confirmed by the pattern of seismic wave attenuation to do so we separately estimate the space averaged parameters intrinsic qi 1 and scattering qs 1 proportional to the correspondent attenuation parameters by applying a modified multiple lapse time window analysis mltwa in order to establish reference background values for the study region mltwa measures the decay of s wave energy with distance and lapse time and fit it to the energy transport equation solution for scattering yielding the seismic albedo b0 qs 1 qt 1 and the extinction length le qt 1 parameters as a function of frequency the knowledge of the separated attenuation parameters allows determining which process of seismic energy dissipation dominates in the region in the present study b0 results to be around0 6 at 1 5 hz and decreases with increasing frequency down to 0 2 indicating that the attenuation of the seismic energy carried by s wave is controlled by intrinsic dissipation rather than by scattering moreover the intrinsic attenuation is frequency dependent f 0 9 for the uniform model and f 0 4 for the crust moho model this behavior well matches with the presence of fluids in the faults and fracture zones in the central apennines in agreement with results from other independent studies in the region finally a comparison among the attenuation parameters estimated for this area and those measured in several areas of italy and other parts of the world is presented together with a discussion on the comparison between the present mltwa attenuation estimates and homologous results obtained for the same area with different approaches

the 1998 and 2004 bovec krn slovenia seismic sequences aftershock pattern focal mechanisms and static stress changes summary we investigate the main seismotectonic aspects of the bovec krn sequences northwestern slovenia caused by the 1998 april 12 md 5 6 and the 12 july 2004 md 5 1 earthquakes the seismicity occurred along an extended right lateral strike slip fault zone trending nw se the analysis involves the aftershock pattern the focal mechanism of the largest events and the stress changes induced by the 1998 main shock the study is performed with high quality earthquake locations obtained with tomographic techniques that provided also velocity images of the fault zone related to the mechanical properties of the medium and to the geometry of the fault the tomographic model shows in the fault zone sharp lateral p wave velocity contrasts and marked lateral vp vs variations and images an extended high rigidity body along the fault where the 1998 and 2004 main shocks are located the aftershock activity is intense along highly heterogeneous zones characterized by sharp variation of vp and vp vs values the spatial distribution of the 1998 aftershocks defines sharp vertical planar features consistent with the orientation of the main strike slip fault while the 2004 aftershock pattern is quite diffuse the tomographic images and the spatial distribution of the aftershocks indicate a fault zone characterized by branches the fault plane solutions of the 1998 and 2004 main shocks show evidence of dextral strike slip motion concordant with the kinematics of the bovec krn fault the largest aftershocks of both sequences are characterized by different types of focal mechanisms and variable plane orientation the different focal mechanisms in the fault zone suggest that the mode of fracture of the largest aftershocks can be influenced by the fault strength heterogeneities imaged by the tomographic inversion the coulomb stress changes caused by the 1998 main shock was calculated to explore the stress transfer mechanism and the earthquake interactions a positive correlation of the coulomb stress increase is found with the largest aftershock md 4 6 and with a part of the aftershocks our modelling shows also that the coulomb stress changes caused by the 1998 main shock and its largest aftershock were not sufficient to trigger the 2004 main shock the locations of the 1998 and 2004 sequences correlate well with areas of increased coulomb stress changes when the regional tectonic loading is considered

three dimensional vp vs variations along the loma prieta rupture zone an inversion of s p seismic wave arrival time data primarily from the program for array seismic studies of the continental lithosphere passcal array deployed in the aftershock zone of the 1989 loma prieta california earthquake has yielded a 3 d model for vp vs variations along the loma prieta rupture zone significant effort was devoted to identifying s to p converted waves which were prevalent at a few of the stations used the inversion method uses 3 d ray tracing in an existing laterally heterogeneous p wave velocity model to determine the initial paths for s waves assuming a constant vp vs the model represents spatial variations in vp vs on a 3 d grid with node spacings of 3 to 15 km horizontally and 3 to 5 km vertically the reduction in data variance computed exactly by applying the vp vs perturbations to the s velocity structure exceeds 65 for the single step inversion we interpret the vp vs model in conjunction with other available geological and geophysical information our major findings are 1 high vp vs along the fault zone in the upper crust indicative of upthrust gabbroic rocks 2 predominantly low vp vs in the lower crust indicative of an underlying quartz rich basement and 3 two areas of low vp vs in the near surface associated with known quartz rich rock sequences one a sandstone and the other granite and or granodiorite we also tentatively identify a boundary between areas of low and slightly high vp vs at depth in the immediate vicinity of the loma prieta mainshock hypocenter our results indicate the diagnostic power of a 3 d vp vs model when it is combined with other geological and geophysical information

separation of depth dependent intrinsic and scattering seismic attenuation in the northeastern sector of the italian peninsula summary we investigated the intrinsic dissipation and scattering properties of the lithosphere under the friuli region northeastern italy using two hypotheses i a uniform earth model and ii two reasonable non uniform layered crustal models for case i we measured the coda q and used the multiple lapse time window analysis mltwa technique to obtain separate estimates of intrinsic absorption and scattering attenuation results for the uniform earth model show that the lithosphere in northeastern italy is characterized by a low scattering attenuation small scattering q inverse q 1 and by a relatively high intrinsic attenuation high intrinsic q inverse q 1 a comparison between the investigated region and other areas around the world shows that both q 1 and q 1 for the friuli region are among the lowest values ever measured with the exception of the southern apennines which has the lowest measured q 1 for case ii numerical simulation of the energy envelopes was performed using two layered earth models where the values of the intrinsic and scattering attenuation coefficients are both within reasonable ranges when compared with the geological information the theoretical envelopes calculated for the homogeneous model give a good fit to the synthetic envelopes calculated for the layered models the best fit is obtained for scattering attenuation coefficients of the uniform model always greater than those of the layered model the main result is consequently that scattering q 1 obtained using the mltwa under the assumption of a uniform medium is overestimated on average by a factor 2 finally coda q 1 appears to be closer to the total q 1 than to the intrinsic q 1 a spredicted

earthquake locations and three dimensional crustal structure in the coyote lake area central california previous work on the simultaneous inversion method has been improved and extended to incorporate iterative solution for earthquake locations and laterally heterogeneous structure approximate ray tracing and parameter separation are important elements of the improved method application of the method to p wave arrival time data recorded by stations of the u s geological survey central california network yields a three dimensional model for the velocity structure of the upper crust in an area encompassing the rupture zone of the coyote lake earthquake of august 1979 very strong correlations between the velocity model and the geology and gravity and magnetic anomalies are observed improved estimates of the locations of earthquakes in the study area are also determined the relocation of explosions indicates epicentral accuracies of the order of a kilometer or better based on the revised hypocentral locations it is concluded that the san andreas fault is vertical in this area with no actual offset between the epicenters and the fault trace in contrast the calaveras has two or more active fault surfaces one nearly vertical and another dipping 75 to the northeast

influence of topography on coseismic displacements induced by the friuli 1976 and the irpinia 1980 earthquakes italy analyzed through a two dimensional hybrid model 1 we investigate the perturbations introduced by the local topography on the coseismic displacement components induced by crustal seismic faults the approach proposed by tinti and armigliato 2002 is applicable to homogeneous two dimensional domains with arbitrary topography of the free surface it uses both analytical results valid for homogeneous spaces and half spaces bounded by a flat free surface ffs and a numerical code solving the equations of equilibrium of linear elasticity through a finite element fe scheme a major characteristic of our hybrid method is that it allows for the correct representation of the displacement components in correspondence with the fault which does not need to be explicitly introduced in the fe mesh we show that in the case of homogeneous domains this makes our approach preferable to pure fe schemes our hybrid approach is here applied to two different disastrous events of the recent italian seismic history for which topography is expected to play an important role namely the 6 may 1976 ms 6 5 friuli and the 23 november 1980 ms 6 9 irpinia basilicata earthquakes for each event we selected hypotheses for the parent fault proposed in the literature and compared the coseismic displacements computed through the widely used analytical models dealing with ffs and through our hybrid approach accounting for the effect of realistic topographies the most relevant effects are observed in the case of the irpinia earthquake depending on the profile chosen the computed misfits can be as high as 19 and 13 for the horizontal and vertical displacements respectively with absolute differences up to 9 and 10 cm

nature of flow and turbulence structure around an in stream vertical plate in a shallow channel and the implications for sediment erosion 1 detailed knowledge of the dynamics of large scale turbulence structures is needed to understand the geomorphodynamic processes around in stream obstacles present in rivers detached eddy simulation is used to study the flow past a high aspect ratio rectangular cylinder plate mounted on a flat bed relatively shallow channel at a channel reynolds number of 2 4 105 similar to other flows past surface mounted bluff bodies the large amplification of the turbulence inside the horseshoe vortex system is because the core of the main necklace vortex is subject to large scale bimodal oscillations the presence of a sharp edge at the flanks of the obstruction fixes the position of the flow separation at all depths and induces the formation and shedding of very strong wake rollers over the whole channel depth compared with the case of a circular cylinder where the intensity of the rollers decays significantly in the near bed region because the incoming flow velocity is not sufficient to force the wake to transition from subcritical to supercritical regime in the case of a high aspect ratio rectangular cylinder the passage of the rollers was found to induce high bed shear stresses at large distances 6 8 d behind the obstruction also the nondimensional values of the pressure root mean square fluctuations at the bed were found to be about 1 order of magnitude higher than the ones predicted for circular cylinders overall this shows that the shape of the in stream obstruction can greatly modify the dynamics of the large scale coherent structures the nature of their interactions and ultimately their capability to entrain and transport sediment particles and the speed at which the scour process evolves during its initial stages

an investigation of the flow and scour mechanisms around isolated spur dikes in a shallow open channel 1 conditions corresponding to the initiation of the erosion and deposition process 1 the present study investigates the flow physics and the role played by the main coherent structures in the scouring processes around a vertical spur dike in a straight channel at conditions corresponding to the start flat bed of the scouring process large eddy simulation les is performed at a relatively low channel reynolds number re 18 000 in the range where most flume studies with clear water scour conditions are conducted similar to these studies the incoming flow is fully turbulent and contains realistic turbulence fluctuations visualization experiments are conducted to better understand the nature of the interactions between the dominant coherent structures playing a role in the erosion process it is found that the structure of the horseshoe vortex hv system at the base of the spur dike changes considerably in time and in vertical sections perpendicular to the trajectory defined by the axis of the main necklace vortex however its intensity is the largest at vertical sections situated around the tip of the spur dike it is in this region that the core of the main necklace vortex oscillates aperiodically between two preferred modes in one of them zero flow mode the necklace vortex is closer to the spur dike and more compact and the near bed jet flow beneath it is weak in the other one back flow mode a strong near bed jet flow convects the primary necklace vortex away from the spur dike and its core is more elongated and less compact this explains the large amplification by about 1 order of magnitude compared to the surrounding turbulent flow of the turbulent kinetic energy and pressure fluctuations inside the hv system in the region situated around the tip of the spur dike and the double peak distribution of the turbulent kinetic energy past the spur dike in the legs of the necklace vortex the intensity of the bimodal oscillations decreases such that they are not observed in spanwise sections situated at more than one channel depth behind the spur dike it is found that the legs of the horseshoe vortices can interact at times with the vortex tubes shed in the detached shear layer dsl and with the tip of the spur dike these events typically result in a significant change in the coherence of the hv system the largest bed shear stress values in the mean flow are present in the strong acceleration region near the tip of the spur dike but high bed shear stress values are also observed beneath the upstream part of the dsl the bed shear stress fluctuations around the local mean values can be very high especially in the region situated beneath the upstream part of the dsl at random times some of the vortices shed in the dsl merge or interact with eddies from the recirculation region this leads to an increase in their strength and to a large increase of the bed shear stress along their path

three dimensional numerical model for flow through natural rivers this paper presents a three dimensional numerical model for simulating flow through natural river reaches the model solves the reynolds averaged navier stokes rans equations closed with the standard ik e turbulence model large scale roughness and multiple islands are directly resolved by employing boundary fitted curvilinear coordinates in conjunction with a multiblock approach small scale bed roughness is accounted for using a two point wall functions approach calculations are carried out for flow through a 4 km stretch of the columbia river downstream of the wanapum dam for which detailed field and laboratory measurements were collected for a range of power plant operating conditions measurements at one operating discharge are employed to calibrate the small scale roughness distribution in the numerical model subsequently the calibrated model is validated by comparing the computed results with laboratory and field measurements for other discharge combinations these comparisons demonstrate the ability of the model to capture most experimental trends with remarkable accuracy

the 1995 kobe earthquake seismic image of the source zone and its implications for the rupture nucleation in order to understand what may have triggered the 1995 kobe japan earthquake and how the rupture proceeded after initiation we determined high resolution three dimensional 3 d p and s wave velocity and poisson s ratio structures in the kobe epicentral area and relocated the aftershocks with the obtained 3 d velocity model we used 64 337 p and 49 200 s wave high quality arrival times from 3634 kobe aftershocks and local microearthquakes recorded by both permanent seismic networks and portable stations that were set up following the kobe mainshock significant velocity variations of up to 6 are revealed in the aftershock area we found that areas with high aftershock activity are generally associated with low poisson s ratio which may be the strong and competent parts of the fault zone and were apt to generate aftershocks the kobe mainshock hypocenter is located in a distinctive zone characterized by low p and s wave velocities and a high poisson s ratio this anomaly exists in the depth range of 16 to 21 km and extends 15 to 20 km laterally this anomaly may be due to a fluid filled fractured rock matrix that contributed to the initiation of the kobe earthquake our interpretation has been supported by many pieces of evidence from hydrological geochemical seismological and geophysical investigations conducted at the kobe earthquake region

a review on the driving mechanism of the tyrrhenian apennines system implications for the present seismotectonic setting in the central northern apennines abstract the formation of the tyrrhenian apennines system has been characterized by a complex distribution of major tectonic events such as opening of basins migration and distortion of orogenic belts retreat of trench zones stopping of consuming processes and starting of new subductions the various aspects of each event such as timing location dimension and deformation style impose important constraints on the genetic mechanism in this work we argue that the numerous constraints implied by all events together may be plausibly and coherently explained as effects of the convergence of the confining africa arabia and eurasia plates crucial evidence for discriminating among the various geodynamic hypotheses so far advanced is provided by the structural tectonic information recently provided by crop seismic sections in the study area the proposed evolutionary history is illustrated by several paleogeographic maps which provide a more detailed reconstruction than previous attempts particular attention is paid to describing the tectonic setting developed since the middle pleistocene in the apennines belt and its connection with seismic activity

seismicity seismogenic structures and crustal stress fields in the greater rome area central italy 1 instrumental seismicity of the greater rome area is analyzed using the most recent seismological database the aim of this study is to identify potential seismogenic structures responsible for the moderate seismicity that characterizes this sector where no surface faulting is expected on the basis of the absence of strong local earthquakes as evidenced by the 2000 year long historical record nevertheless in light of the great value and the high vulnerability of the architectural and monumental patrimony of rome even the occurrence of moderate events imposes a careful assessment of the hazard linked to the presence of active faults that are undetectable by means of classic geological field investigation seismic data here analyzed belong to the period 1997 2008 and show local magnitude ml ranging from 1 5 to 4 7 to better constrain the hypocentral depths we computed the vp vs ratio using a modified wadati method and the minimum 1 d velocity model that approximates the seismic structure of the study area moreover we applied a double difference hypocentral determination technique to improve earthquake locations most of the located seismicity appears to be concentrated within seven main clusters spatial distribution of the seismicity allowed us to identify several seismogenic structures corresponding to previously undetected or only supposed active faults the stress tensor obtained by inverting the focal mechanisms computed in this study is in agreement with the ne sw extensional tectonic stress active in the inner chain of the apennines although there is evidence of some local stress field heterogeneities

internal waves in the strait of messina studied by a numerical model and synthetic aperture radar images from the ers 1 2 satellites a new numerical two layer model is presented which describes the generation of internal tidal bores and their disintegration into internal solitary waves in the strait of messina this model is used to explain observations made by the synthetic aperture radar sar from the european remote sensing satellites ers 1 and ers 2 the analysis of available ers 1 2 sar data of the strait of messina and adjacent sea areas show that 1 northward as well as southward propagating internal waves are generated in the strait of messina 2 southward propagating internal waves are observed more frequently than northward propagating internal waves 3 sea surface manifestations of southward as well as northward propagating internal waves are stronger during periods where a strong seasonal thermocline is known to be present 4 southward propagating internal bores are released from the sill between 1 and 5 hours after maximum northward tidal flow and northward propagating internal bores are released between 2 and 6 hours after maximum southward tidal flow and 5 the spatial separation between the first two internal solitary waves of southward propagating wave trains is smaller in the period from july to september than in the period from october to june the numerical two layer model is a composite of two models consisting of 1 a hydrostatic generation model which describes the dynamics of the water masses in the region close to the strait s sill where internal bores are generated and 2 a weakly nonhydrostatic propagation model which describes the dynamics of the water masses outside of the sill region where internal bores may disintegrate into internal solitary waves due to a technique for movable lateral boundaries the generation model is capable of simulating the dynamics of a lower layer that may intersect the bottom topography the proposed generation propagation model depends on one space variable only but it retains several features of a fully three dimensional model by including a realistic channel depth and a realistic channel width it is driven by semidiurnal tidal oscillations of the sea level at the two open boundaries of the model domain numerical simulations elucidate several observed characteristics of the internal wave field in the strait of messina such as north south asymmetry times of release of the internal bores from the strait s sill propagation speeds and spatial separations between the first two solitary waves of internal wave trains

effects of groyne layout on the flow in groyne fields laboratory experiments this research is aimed at finding efficient alternative designs in the physical economical and ecological sense for the standard groynes as they are found in the large rivers of europe in order to test the effects of various groyne shapes on the flow in a groyne field experiments were performed in a physical model of a schematized river reach geometrically scaled 1 40 four different types of schematized groynes were tested all arranged in an array of five identical groyne fields i e standard reference groynes groynes with a head having a gentle slope and extending into the main channel permeable groynes consisting of pile rows and hybrid groynes consisting of a lowered impermeable groyne with a pile row on top flow velocities were measured using particle tracking velocimetry the design of the experiment was such that the cross sectional area blocked by the groyne was the same in all cases depending on the groyne head shape and the extent of submergence variations in the intensity of vortex shedding and recirculation in the groyne field were observed the experimental data are used to understand the physical processes like vortex formation and detachment near the groyne head it is demonstrated that the turbulence properties near and downstream of the groyne can be manipulated by changing the permeability and slope of the groyne head it is also observed that for submerged conditions the flow becomes complex and locally dominated by three dimensional effects which will make it difficult to predict by applying depth average numerical models or by three dimensional models with a coarse resolution in the vertical direction

a nonlinear model of the shoaling and refraction of interfacial solitary waves in the ocean part i development of the model and investigations of the shoaling effect abstract oceanic internal waves are frequently observed to be of large amplitude and to exhibit significant wave front curvature as seen in synthetic aperture radar images the aim of this paper is to present a refraction model in two horizontal dimensions including moderate amplitude effects to model these common properties of internal waves the model incorporates second order nonlinearity and uses a ray method to allow arbitrary refraction for these preliminary investigations with the model a two layer ocean is assumed with an upper layer thickness of 50 m and a density difference across the layers of 0 5 kg m 3 an important aspect affecting the refraction of nonlinear waves is shoaling as the phase speed of a nonlinear wave depends on its amplitude in part i of this paper the development of the model is described and the shoaling phenomenon is investigated in detail the shoaling of interfacial internal solitary waves over both slowly varying and rapidly varying bathymetry is studied a wedg

a mean residence time relationship for lateral cavities in gravel bed rivers and streams incorporating streambed roughness and cavity shape 2 accurate estimates of mass exchange parameters in transient storage zones are needed to better understand and quantify solute transport and dispersion in riverine systems currently the predictive mean residence time relies on an empirical entrainment coefficient with a range in variance due to the absence of hydraulic and geomorphic quantities driving mass exchange two empirically derived relationships are presented for the mean residence time of lateral cavities a prevalent and widely recognized type of transient storage in gravel bed rivers and streams that incorporates hydraulic and geomorphic parameters the relationships are applicable for gravel bed rivers and streams with a range of cavity width to length w l aspect ratios 0 2 0 75 shape and reynolds numbers re ranging from 1 0 10 4 to 1 0 10 7 the relationships equate normalized mean residence time to nondimensional quantities froude number re w l depth ratio ratio of cavity to shear layer depth roughness factor ratio of shear to channel velocity and shape factor representing degree of cavity equidimensionality one relationship excludes bed roughness equation 13 and the other includes bed roughness equation 14 the empirically derived relationships have been verified for conservative tracers r 2 of 0 83 within a range of flow and geometry conditions topics warranting future research are testing the empirical relationship that includes the roughness factor using parameters measured in the vicinity of the cavity to reduce the variance in the correlation and further development of the relationship for nonconservative transport

a numerical investigation of coherent structures and mass exchange processes in channel flow with two lateral submerged groynes 1 large eddy simulation is used to investigate the dynamics of the main coherent structures present in the flow around two vertical submerged groynes situated in a long flatbed open channel the mass exchange processes between the embayment region and the main channel are investigated by studying the ejection of a contaminant introduced instantaneously inside the embayment the instantaneous and mean structure of the horseshoe vortex system forming at the base of the upstream groyne and the bed shear distributions that determine the evolution of the scour in the groyne region are investigated it is found that the amplification of the bed shear stress in the accelerating region around the tip of the upstream groyne is around one order of magnitude larger relative to the mean bed shear stress in the incoming flow analysis of the instantaneous flow fields shows that the eddies that are shed inside the horizontal and vertical detached shear layers play an important role in controlling the mass exchange at the lateral and roof interfaces it is found that most of the pollutant leaves the embayment through the roof and bottom lateral sections the overall mass exchange process is qualitatively different and substantially accelerated compared to the case when the groynes are emerged however it is shown that similar to the emerged case the decay of the mass of contaminant within the embayment cannot be characterized by a unique value of the exchange coefficient used in simple dead zone theory models

the 2002 molise earthquake sequence what can we learn about the tectonics of southern italy abstract on october 31 2002 a m l 5 4 earthquake occurred in southern italy at the margin between the apenninic thrust belt to the west and the adriatic plate to the east in this area neither historical event nor seismogenic fault is reported in the literature in spite of its moderate magnitude the earthquake caused severe damage in cities close to the epicenter and 27 people out of a total of 29 casualties were killed by the collapse of a primary school in s giuliano di puglia by inverting broadband regional waveforms we computed moment tensor solutions for 15 events as small as m l 3 5 m w 3 7 the obtained focal mechanisms show pure strike slip geometry mainly with focal planes oriented to ns sinistral and ew dextral in several solutions focal planes are rotated counterclockwise in particular for later events occurring west of the mainshock from the relocated aftershock distribution we found that the mainshock ruptured along an ew plane and the fault mechanisms of some aftershocks were not consistent with the mainshock fault plane the observed stress field resulting from the stress tensor inversion shows a maximum principal stress axis with an east west trend n83 w whereas the minimum stress direction is almost n s considering both the aftershock distribution and moment tensor solutions it appears that several pre existing faults were activated rather than a single planar fault associated with the mainshock the finite fault analysis shows a very simple slip distribution with a slow rupture velocity of 1 1 km s that could explain the occurrence of a second mainshock about 30 h after finally we attempt to interpret how the molise sequence is related to the normal faulting system to the west along the apennines and the dextral strike slip mattinata fault to the east

a model for the alboran sea internal solitary waves abstract the propagation into the alboran sea of the interface depression generated at the strait of gibraltar by the interaction of the semidiurnal tidal current with the main camarinal sill is studied numerically by using a unidirectional model with two horizontal space dimensions an initial waveform within the strait is determined whose evolution corresponds with the train of internal solitary waves detected in the alboran sea by means of current measurements at different depths as described by kinder the agreement is good for two points located at about 45 km east of the strait the first aligned with the strait axis and the second 20 km to the north moreover the shape and amplitude of this initial condition are in agreement with a typical interface depression generated in the strait by the interaction of the tidal current with the sill a series of numerical experiments with different initial conditions is also performed to study the sensitivity of the model results to changes in the initial i

numerical investigation of flow hydrodynamics in a channel with a series of groynes the flow hydrodynamics in a straight open channel containing a multiple embayment groyne field on one of its sides is investigated numerically using large eddy simulation the vertical groynes are fully emerged the mean flow depth in the groyne region is about half that of the main channel and the length and width of the embayments are much larger than the mean depth in the embayment region the model is validated using mean velocity and turbulent fluctuations data collected at the free surface in a previous experimental study it is found that despite the fact that the flow inside the main recirculation eddy in the embayments can be characterized as being quasi two dimensional the flow inside the mixing layer region between the embayments and the channel is strongly nonuniform over the depth as this region controls the mass exchange processes between the groyne field and the main channel a three dimensional description of the flow in this area is essential the large scale eddies that populate the mixing layer can penetrate the embayment region over lateral distances of the order of the channel depth these eddies advect with them channel fluid inside the embayment eventually the channel fluid is mixed with the embayment fluid by the small scales the other main mixing mechanism is due to the injection of patches of high vorticity mixing layer fluid near the tip of the downstream groyne and their subsequent convection in the form of a wall attached jet like flow into the embayment first parallel to the downstream groyne face and then to the sidewall it is shown that on average most of the fluid leaves the embayment region via the top layer of the embayment channel interface upstream half and enters the embayment region at levels situated around the middepth practically over the whole length of the embayment of the interface surface this explains why the mass exchange coefficients are overestimated when predicted using methods that employ floating particles as a tracer the instantaneous bed shear stress inside the cavity is found to peak close to the downstream groyne face of each embayment and to show a high variability around the mean values due to the interaction of the mixing layer eddies with the tip of the groynes and the formation of the jet like flow parallel to the droyne face

imaging the crustal structure throughout the east anatolian fault zone turkey by local earthquake tomography this paper presents new models of the seismic velocity structure of eastern anatolia turkey we applied a local earthquake tomography method to arrival time data produced by local and regional events in eastern anatolia to understand the three dimensional seismic velocity and vp vs models and their correlation with the geological evolution and tectonic processes in the study area the data are obtained from 78 broadband seismic stations owned by the earthquake department of the disaster and emergency management presidency for the period between 2008 and 2017 seven depth cross sections are taken along various segments of the east anatolian fault zone travel times of 53 099 phase readings 29 122 p phase and 23 977 s phase picks from 4249 high quality earthquake recordings are analysed to develop 3 d vp lithological and vp vs petrological models of the study area the resulting p wave velocities describe intrusive magmatic bodies sediment thickness and the structure of the basin the vp vs structures aid to limit the position of the faults areas of weakness and gas or liquid saturated units with regions of high pore pressure four main seismic crustal layers down to 40 km are determined the upper crust 0 8 km has vp 4 6 km s whereas in the middle crust 9 20 km a vp perturbation between 4 6 and 5 8 km s is observed in the lower crust 20 35 km vp changes from 5 9 to 7 3 km s and in the upper mantle layer below 36 km vp exceeds 7 4 km s in all cases seismic velocities are well resolved in the first 40 km tomograms are compatible with the geological characteristics of the region dominant high p velocity values are observed beneath the collision zone conrad discontinuity is detectable at 20 km depth while moho depth is observed to vary between 30 and 40 km in the study area

source parameters and stress release of seismic sequences occurred in the friuli venezia giulia region northeastern italy and in western slovenia abstract the source parameters of the major events of a swarm and of two seismic sequences occurred in the friuli area northeastern italy and in western slovenia were estimated the claut swarm c96 occurred since the end of january to june 1996 with a md 4 3 major shock and it appears composed of three sub sequences the two sequences are the kobarid sequence k98 started on april 12 1998 with a md 5 6 mainshock and the m te sernio s02 sequence caused by the february 14 2002 earthquake md 4 9 acceleration and velocity data recorded by the local seismic network of the istituto nazionale di oceanografia e di geofisica sperimenale ogs and corrected for attenuation were employed to estimate seismic moments and radiated energies source dimensions were inferred from the computed corner frequencies and the stress release was estimated from the brune stress drop the apparent stress and the rms stress drop on the whole seismic moments range from 1 7 1012 to 1 1 1017 n m and radiated energies are in the range 106 1013 j brune stress drops are scattered and do not show any evidence of a self similarity breakdown for sources down to 130 m radius the radiated seismic energy scales as a function of seismic moment with a slope of the scaling relation that decreases for increasing seismic moments the mechanism of stress release was analyzed by computing the parameter of zuniga zuniga r 1993 frictional overshoot and partial stress drop which one bull seismol soc am 83 939 944 the k98 and s02 sequences are characterized by a wide range of the parameter with stress drop mechanism varying from partial locking to overshoot cases the values of the c96 swarm are more homogeneous and close to the orowan s condition the radiated seismic energy and the ratio of stress drop between mainshock and aftershocks appear different among the analyzed cases we therefore investigated the relationship between the stress parameters of the main shock and the energy radiated by the aftershock sequences for this purpose we also estimated the source parameters of two other sequences occurred in the area with mainshocks of md 4 1 and 5 1 respectively we found a positive correlation between the brune stress drop of the mainshock and the ratio between the radiated energy of the mainshock and the summation of the energies radiated by the aftershocks

local source tomography applications to italian areas we describe three study cases in which we used local earthquake and shot travel time residuals to investigate the upper crustal structure of three regions in italy we inverted for velocity and hypocentral parameters using a damped least squares technique making use of parameter velocity and hypocentre separation the three studied regions are in italy namely a the vulsinian volcanic complex latium where there is an active geothermal field b the irpinia campania lucania region in the southern appennines site of the strongest earthquake in italy for at least 65 years november 1980 ms 6 9 c the friuli region in northeastern italy where another strong earthquake ms 6 5 occurred in 1976 the computed shallow velocity models generally correspond with surface geological structures for the three studied areas the main results are respectively a a low velocity anomaly detected in the centre of the vulsinian volcanic complex at a depth of 5 8 km probably due to anomalous heat flow caused by a partially molten or cooling intrusive body b the identification of a deep 10 km discontinuity in the crust beneath the irpinia fault zone approximately corresponding with the fault extension at depth c the detection of a wedge of high velocity high density material at seismogenic depth 5 10 km beneath the friuli region interpreted as a buried thrust of the metamorphic basement

numerical modeling of the semidiurnal tidal exchange through the strait of gibraltar 1 a three dimensional sigma coordinate free surface model is used to investigate the semidiurnal tidal exchange through the strait of gibraltar the model makes use of a coastal following curvilinear orthogonal grid that includes the gulf of cadiz and the alboran sea with very high resolution in the strait 500 m a lock exchange initial condition is used the western part of the model domain is filled with atlantic water whereas the eastern part is filled with mediterranean water the model is forced at the open boundaries through the specification of the semidiurnal m2 and s2 tidal surface elevation the model is run over a spring neap cycle fortnightly period and the results are compared with available observed data simulated cotidal maps of the m2 and s2 tidal elevation components are in quantitative and qualitative good agreement with observed data as well as with the simulated major and minor axis of tidal ellipse the model reproduces the generation and the subsequent propagation of internal bores both eastward and westward showing that they are always generated during the fortnightly period however the principal aim of this work is to quantify the effects of tidal forcing on mean quantities entrainment and transport of atlantic and mediterranean water along the strait model results reveal that the contribution of the semidiurnal tidal component m2 to the transport is relevant over camarinal sill whereas it is negligible at the eastern end of the strait model results indicate also that the effect of the semidiurnal tide is to increment the mean transport by about 30 both for the inflow and the outflow

modulation of outer bank erosion by slump blocks disentangling the protective and destructive role of failed material on the three dimensional flow structure the three dimensional flow field near the banks of alluvial channels is the primary factor controlling rates of bank erosion although submerged slump blocks and associated large scale bank roughness elements have both previously been proposed to divert flow away from the bank direct observations of the interaction between eroded bank material and the 3 d flow field are lacking here we use observations from multibeam echo sounding terrestrial laser scanning and acoustic doppler current profiling to quantify for the first time the influence of submerged slump blocks on the near bank flow field in contrast to previous research emphasizing their influence on flow diversion away from the bank we show that slump blocks may also deflect flow onto the bank thereby increasing local shear stresses and rates of erosion we use our measurements to propose a conceptual model for how submerged slump blocks interact with the flow field to modulate bank erosion

stress and the direction of slip on fault planes the shear stress direction on a fault plane depends only on four of the six components of the stress tensor assuming only that the slip direction marks the shear stress direction on any fault plane and that stress is homogeneous it is possible to estimate these four stress parameters from populations of fault planes with known slip directions as several workers have observed different formulations of the problem may yield varying best fitting stresses and estimates of uncertainty in the simplest case no assumptions are made regarding the orientations of fault planes relative to the stress tensor thus the technique allows for the possibility that the fault planes may be very weak here we present simple analytical and graphical descriptions of the field of admissible fault geometries relative to any four parameter stress model which can be used to illustrate the significance of various inverse strategies in particular this paper explores the effects of using two alternative measures of misfit between an observed fault datum and stress model 1 the pole rotation the angle between the observed and predicted slip direction on the observed fault plane and 2 the minimum rotation the smallest angle between the observed fault geometry and any fault geometry which is consistent with the model by allowing for variation of the fault plane as well as the slip vector the minimum rotation procedure generally achieves a more stable and presumably realistic estimate of the actual discrepancy between a fault observation and stress model than the pole rotation procedure in a test case using 17 earthquake focal mechanisms from the yuii region of eastern taiwan separate inversions based on the two misfit criteria yield different optimum stress models and uncertainty estimates additional constraints on the stress tensor such as the effect of friction can be superimposed on the ones used here

three dimensional vp and vp vs structure of the upper crust in the erzincan basin eastern turkey 1 using aftershocks of the 13 march 1992 erzincan earthquake ms 6 8 three dimensional vp and vp vs velocity structure of the erzincan basin and its surroundings were modeled by local earthquake tomography travel times of body waves belonging to 1025 selected high quality events recorded by 58 temporary stations were inverted iteratively and simultaneously by using the simul2000 algorithm synthetic and resolution tests were performed to analyze the sensitivity of tomographic results and model parameterization the resulting 3 d vp and vp vs tomographic images show velocity anomalies related to geologic and tectonic structures beneath the erzincan basin while low vp anomalies down to 2 3 km depths are associated to thick neogene sediments deposited in the erzincan basin high vp anomalies indicate bed rocks and intrusive magmatic rocks beneath the mountain ranges vp vs anomalies are an important indicator of local tectonic structures and the physical mechanical and compositional variations in the rocks the low vp vs anomalies 1 7 observed at shallow depths 0 4 km track the main fault systems and thus the weakness zones in the basin the high vp vs anomalies 1 9 located between 4 and 6 km depth in the southeast of the erzincan basin may correspond to fluid saturation high pore pressure and carbonate content in the rock matrix the high vp vs ratios play an important role for increasing seismicity in this area because of the fluid saturation and the high pore pressure finally on the basis of the 3 d tomographic images basement of the erzincan basin deepens down to about 10 km depth and possesses an irregular and asymmetric shape the thick and unconsolidated sedimentary layer increases seismic risk to erzincan and other cities located on the basin as it magnifies ground motion caused by large earthquakes

a statistical analysis of extreme events in current variations due to internal waves from the australian north west shelf measurements of current fluctuations due to internal waves obtained from two fixed point moorings on the australian north west shelf have been analyzed with the aim of calculating the probability of short scale large amplitude internal waves exceeding particular values such waves are generated as a result of breaking or hydrodynamical instability of the semidiurnal internal tide the statistical stationarity of each record has been checked and it is shown that the records can be used for the calculation of the frequency by which currents exceed a particular value for wave heights double amplitudes of less than 60 cm s 1 the theoretical forms for exceedance frequency from the theory of extreme statistics have been checked and it is shown that for one location a power asymptotic provides a slightly better descriptor of the statistics than an exponential asymptotic and for the other location an exponential asymptotic is found to provide the better fit the exceedance frequency for internal waves near the australian north west shelf is found to be less than 1 3 waves per hour the exceedance probability for each location has been calculated using poisson statistics

a 3d vs model of the upper mantle beneath italy insight on the geodynamics of central mediterranean abstract we compute a high resolution vs model of the upper mantle underneath italy by inverting relative residuals of s wave arrivals from teleseisms recorded at the italian broad band national seismic network we also present a model of vp vs perturbations obtained from similarly resolved p and s wave velocity models the joint analyses of vs and vp vs models suggests that compositional variations concur with temperature variations to generate the observed velocity patterns giving deeper insight into the upper mantle structure the investigation of coherent high vs and high vp anomalies permits a comprehensive picture of the main oceanic domains involved in the puzzling subduction system of the central mediterranean slab windows and tears developed in the ionian slab are highlighted by regions of low vp low vs and high vp vs anomalies the adria continental lithosphere is characterized by high vp high vs and low vp vs anomalies that trace the sinking of eclogitized material underneath the apennines and the eastern alps chains the overall tomographic results yield the development of a new conceptual model for the alps and apennines formation in which three basic processes occurred in different time and different locations all around the alpine apennines system continental collision slab break off and delamination of the upper plate lithosphere

a propagation model for the internal solitary waves in the northern south china sea a two dimensional regularized long wave equation model is developed to study the dynamic mechanisms of the propagation and evolution of the internal solitary waves isws in the northern south china sea scs it is shown that the bottom topography would cause the polarity reversal of isws the change of the local wave crestline shape and some diminution in wave amplitude even if the isws are induced at the small sill channel along the luzon strait they could propagate westward with their crestlines covering a large area in the latitudinal direction in the northern scs when there are two trains of isws propagating from the same source site with a time lag but different amplitudes of initial solitons the latter train of isws with a larger amplitude may catch then swallow the former one with a smaller amplitude and the wave amplitude of the merged isw train decreases while the wave number increases when there are two trains of isws propagating from the different source sites at the same time with the same amplitude of initial solitons the crestlines of the two isw trains may meet and a new leading soliton is induced at the connection point once the isw trains collide with the island before the island a weak isw train is reflected behind the island the former crestlines of the isw train are torn by the island into two new trains which may reconnect after passing around the island the propagation direction the wave amplitude and the reconnection point of the new merged isw train behind the island depend on the relative orientation of the original soliton source site to the island

critical stress difference fault orientation and slip direction in anisotropic rocks under non andersonian stress systems abstract the coulomb navier failure criterion is applied to geological faulting in the general three dimensional case of rocks containing arbitrarily oriented strength anisotropies and subject to non andersonian stress systems i e with none of the principal stresses acting in a vertical direction general expressions for the critical stress difference necessary to cause failure as a function of depth are given in terms of material parameters pore fluid pressure orientation of the stress field and orientation of the strength anisotropy the range of angles between a plane of anisotropy and the maximum principal stress direction for which slip occurs along the pre existing anisotropy rather than along a new fault is calculated as a function of depth for different stress regimes when the stress field is non andersonian and or strength anisotropies not containing the intermediate stress direction occur in the rock faulting generally is oblique slip a kinematic classification of faulting is given on the basis of the angle between the strike direction and the slip direction on the fault plane triangular diagrams analogous to those used in petrology are introduced to describe i faulting in isotropic rock subject to arbitrarily oriented stress fields and ii faulting in anisotropic rock when one principal stress direction is vertical the type of faulting as a function of stress field and anisotropy orientation can be read off directly from these diagrams

three dimensional seismo tectonics in the po valley basin northern italy the po valley northern italy is a composite foreland foredeep basin caught in between the southern alps and northern apennine mountain belts by integrating the 3d structural model of the region with the public earthquake dataset the seismo tectonics of the basin is shown at different scales of observation the three dimensional geo volumeis used to reviewthe seismicity around the region and validate the structure earthquake association for such a complex tectonic framework despite the overall uncertainty due to the original data distribution quality as well as the crustal scale model dimension the direct correlation between structures and seismicity a confirms the po valley region as an active tectonic system and b allows the whole structural architecture to be revised by a unique three dimensional perspective and approach this study also indicates that 3d methodology is a powerful tool for better understanding of highly complex seismo tectonic situations at both regional and local scales

the application of computational fluid dynamics to natural river channels eddy resolving versus mean flow approaches in the last decade as computing power has increased there has been an explosion in the use of eddy resolving numerical methods in the engineering earth and environmental sciences for complex geomorphic flows where accurate field investigations are difficult to perform and where experiments may be difficult to scale these numerical approaches are beginning to give key insights into the nature of these flows eddy resolving methods such as large and detached eddy simulation les des may be contrasted with the time averaged three dimensional simulations that only really began to be applied seriously in geomorphology fifteen years ago while the potential of les for geomorphology has been examined previously des is a relatively recent method that deserves further consideration in this paper we explain the method and then utilise examples from meander and confluence flows as well as flow near the bed of a gravel bed river to highlight the improvements to both the representation of the mean flow and to the representation of time varying processes that result from the use of les des some suggestions are provided for the future use of such techniques in geomorphology

internal hydraulics solitons and associated mixing in a stratified sound observations of tidally forced flow in a constricted and sill like region of a highly stratified sound are examined as a problem of two layer hydraulic exchange based on the current and salinity data time and space dependent hydraulic conditions along the sound are discussed it will be shown that the sound is subject to internal hydraulic controls at several locations which account for the generation of strong internal hydraulic bores and drops in the upper layer internal solitary waves with 3 6 rain period were found in the upstream propagating bore using results from different models of the solitary wave based on the korteweg de vfies kdv equation it is shown that the second order nonlinear term must be included in the two layer model results from a first order continuously stratified model solved using the lowest mode eigenfunction gave similar results as the second order two layer model this implies that two layer models may ignore some properties of the real fluid and that internal soiltons are also sensitive to the stratification characteristics of the water column the vertical velocity shear hydraulic characteristics of the flow and the presence of solitary waves were major contributors to vertical mixing in the sound

investigation of two elemental error sources in boat mounted acoustic doppler current profiler measurements by large eddy simulations measurements of water discharge and flow velocities in riverine and tidal environments are commonly made with acoustic doppler current profilers adcps mounted on a moving boat this paper presents results of high resolution large eddy simulations les conducted to investigate two elemental error sources in adcp measurements from a moving boat one of these errors is due to the flow disturbance induced by the boat mounted adcp the other error is due to the lack of flow homogeneity in horizontal layers assumed by the adcp algorithm to compute orthogonal velocities from the measured radial velocities along the acoustic beams the first error is investigated by comparing les results for an undisturbed flow field with les results for a flow field disturbed by a boat mounted adcp the second error is investigated by comparing the velocities beneath the adcp simulated by les with virtual adcp velocities which are obtained by applying the adcp algorithm to les velocities data mined along the path of the acoustic beams of the virtual profiler the distribution of the reynolds stresses beneath the adcp estimated with the adcp algorithm from the virtual adcp velocity data are also compared with those obtained from the les solutions for both the undisturbed and adcp disturbed flows results show that the boat significantly disturbs the flow field and that the disturbed flow field is qualitatively different from the flow fields observed around an isolated adcp no boat

stress and strain tensors based on focal mechanisms in the seismotectonic framework of the friuli venezia giulia region northeastern italy the principal axes of stress and strain are inferred for the seismotectonic zones of the friuli venezia giulia region which forms the eastern part of the european southern alps this region corresponds to a polyphase deformational belt formed during the meso and neoalpine compressions from the eocene to plio quaternary several distinct seismotectonic zones are recognized by comparing seismological and tectonic characteristics inference of the stress and strain tensors is based on 243 fault plane solutions corresponding to earthquakes occurring between 1984 and 2001 magnitude range 2 1 5 6 the analysis reveals two main regional stress patterns a strike slip regime active in the eastern and northwestern parts of the area under study and dominant thrusting processes in the central and western zones the orientation of the maximum principal stress varies from north northwest south southeast to north northeast south southwest the stress magnitude ratio of the calculated stress tensors varies from 0 4 to 0 7 the orientation of the maximum shortening axis is generally north northwest south southeast changing to north northeast south southwest in the southeastern part of the region for most seismotectonic domains the inferred strain pattern is quite concordant with the surface tectonics the orientations of the principal axes of stress and strain are in most cases similar the complex regional tectonic structure consisting of two indented tectonic wedges appears to control the patterns of horizontal stress and strain

impact of current wave interaction on storm surge simulation a case study for hurricane bob 1 hurricane bob moved up the u s east coast and crossed over southern new england and the gulf of maine with peak marine winds up to 54 m s 100 mph on 19 20 august 1991 causing significant damage along the coast and shelf a 3 d fully wave current coupled finite volume community ocean model system was developed and applied to simulate and examine the coastal ocean responses to hurricane bob results from process study oriented experiments showed that the impact of wave current interaction on surge elevation varied in space and time more significant over the shelf than inside the inner bays while sea level change along the coast was mainly driven by the water flux controlled by barotropic dynamics and the vertically integrated highest water transports were essentially the same for cases with and without water stratification the hurricane induced wave current interaction could generate strong vertical current shear in the stratified areas leading to a strong offshore transport near the bottom and vertical turbulent mixing over the continental shelf stratification could also result in a significant difference of water currents around islands where the water is not vertically well mixed

tectonic geomorphology of the triglav lakes valley easternmost southern alps nw slovenia abstract we present a study on the impact of litho structural setting and neotectonic activity on meso and macro scale relief production in alpine areas the topography of the high alpine triglav lakes valley nw slovenia was studied by means of detailed mapping and stratigraphic study of the valley the triglav lakes valley is characterised by a generally asymmetric transverse e w profile a very steep eastern slope a relatively flat valley and a relatively gentle western slope on the transverse profile the valley floor is essentially flat gently dipping towards the east in the longitudinal cross section however the valley floor is marked by sharply defined fault blocks extending in a w e to nw se direction additionally the highest block elevations 2100 m is in the northern part of the valley the lowest elevations 1600 m in the southern part of the valley our research shows that the triglav lakes valley directly represents the topographic expression of paleogene neogene thrusting and faulting having recorded the following geomorphologic evolutionary stages 1 an oligocene to early miocene w vergent thrusting phase with steep w facing slopes of the eastern part of the valley directly representing the thrusting front and 2 a neogene to present strike slip faulting in nne ssw direction with two bifurcating right lateral strike slip systems we show that the triglav lakes valley almost perfectly mimics the wedge shaped damage zone located between these faults

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

average strain rate in the italian crust inferred from a permanent gps network ii strain rate versus seismicity and structural geology summary high quality weekly solutions for the coordinates of 45 permanent gps stations spanning 1 6 years and covering the alpine mediterranean area are used to estimate a horizontal velocity field aligned with the itrf2000 velocity datum after subtracting model velocities for the eurasian plate we show that the residual velocity field north of the apennines in the adriatic dinaric region describes a nne trending tectonic flow with a negative velocity gradient from 6 mm yr 1 ne of the apennines to virtually zero ne of the dinarids in the calabria region we observe a divergent pattern with nnw orientation which turns to west as one moves north towards tuscany very small residual velocities are observed for stations in the sardinia corsica block spain southern france and north of the alps this regional pattern of velocities defines areas of intraplate strain on the basis of good station coverage and of a strain rate value above a threshold we define five provinces calabria central apennines both in the extensional regime and north adriatic eastern alps and south adriatic under compression we show that the orientations of the principal strain rate axes agree with the stress pattern that is inferred from local seismicity a comparison of the geodetically determined strain rate with the strain rate associated with the seismic moment of earthquakes in the past 30 yr shows that each province may differ considerably from the others in the amount of seismic moment that is accommodated by surface strain for example the umbria seismic sequence of 1997 seems to have released a seismic moment that was not exceptionally large but concentrated over a short time interval so that the equivalent coseismic strain rate was larger than the value observed geodetically on average depending on the assumptions on the seismogenic volume and time span 70 100 per cent of the surface strain seems to be accommodated by the release of seismic moment in the upper italian crust

seismic properties of highly strained marbles from the splugenpass central alps abstract seismic reflection profiling across the central alps nfp20 shows strong reflectors some of which correspond to a mesozoic marble zone which underlies the contact between the tambo and suretta nappes by means of experimental velocity measurements at confining pressures up to 300 mpa on rock samples collected in the marble zone we determined the seismic properties of these marbles and calculated their reflection coefficients in order better to constrain the seismic interpretation the main findings are as follows 1 a marbles exhibit v p anisotropy up to 9 with orthorhombic or transverse isotropic tetragonal symmetry due to the crystallographic preferred orientation of calcite 2 b compressional waves shear waves and shear wave splitting are very sensitive to the type of fabric presence or absence of an r axes concentration 3 c interfaces between marbles and amphibolites or orthogneisses could be good reflectors in normal incidence reflection

post messinian drainage changes triggered by tectonic and climatic events eastern southern alps italy abstract the messinian quaternary history of tectonic and climatic control on sedimentation in the eastern southern alps northern italy was reconstructed using an integrated petrographic and sedimentological analysis of five sedimentary successions these units mainly consist of fluvial conglomerates of the tagliamento sequence deposited within the eastern southern alps since the upper miocene messinian salinity crisis at that time the closure of marine gateways between the atlantic ocean and the mediterranean sea caused a drop in sea level causing exchanged fluvial erosion and widening of the alpine catchments sediment composition in the upper miocene to lower pliocene units shows an abrupt change in the source areas from sediments characterized by carbonate rock fragments to detritus rich in low grade metamorphic grains in spite of tectonic activity within the eastern southern alps no major modifications in sediment supply took place during the pliocene early pleistocene time span in the middle pleistocene the first major expansion of the alpine glaciers triggered a change in drainage patterns and a marked increase in erosion rates predominantly climatic control on sedimentation in the tagliamento basin and the erosion of the carnic alps produced sediments rich in quartz siltstone and metamorphic rock fragments deposited in the upper pleistocene unit and in modern river sediments

an improved method for determining the regional stress tensor using earthquake focal mechanism data application to the san fernando earthquake sequence the orientations of fault planes and slip directions indicated by a population of earthquake focal mechanisms can be used to determine best fit regional principal stress directions and r 2 1 3 1 a measure of relative stress magnitudes under the assumption of uniform stress in the source region this analysis allows for the possibility that failure occurs on preexisting zones of weakness of any orientation in the inversion we perform a grid search of stress models to find the one which requires the smallest total rotation of all the fault planes that is needed to match the observed and predicted slip directions the method allows for errors in orientations of both the fault planes and slip directions we have an objective means for identifying the more likely of the two possible fault planes from each focal mechanism relative to a given stress model thus we do not face the problem of ambiguity of nodal planes which plagues other analyses of this kind by using a grid search of stress models rather than a linearization scheme we are able to perform a realistic error analysis and thus establish confidence limits for the preferred regional stresses the method can be used to investigate possible stress inhomogeneities during earthquake sequences by analyzing subsets of the data population the technique has been applied to 76 events from the san fernando earthquake sequence for which we have found best fit stresses plunge and azimuth 1 7 187 2 27 281 3 62 84 and r 0 65 the average misfit between this stress model and all the data is about 8 and all but eight of the aftershocks have misfits of less than 20 these values are considerably less than the uncertainty of the focal mechanism determinations therefore significant stress inhomogeneities are not required by the data our analysis does not support the suggestion of a change in stresses during the aftershock sequence as proposed by others on the basis of an apparent change in focal mechanisms

recent seismicity and crustal stress field in the lucanian apennines and surrounding areas southern italy seismotectonic implications abstract we analyzed the instrumental seismicity of southern italy in the area including the lucanian apennines and bradano foredeep making use of the most recent seismological data base available so far p and s wave arrival times recorded by the italian national seismic network rsnc operated by the istituto nazionale di geofisica e vulcanologia ingv were re picked along with those of the saptex temporary array deployed in the region in the period 2001 2004 for some events located in the upper val d agri we also used data from the eni agip oil company seismic network we examined the seismicity occurred during the period between 2001 and 2006 considering 514 events with magnitudes m 2 0 we computed the v p v s ratio obtaining a value of 1 83 and we carried out an analysis for the one dimensional 1d velocity model that approximates the seismic structure of the study area earthquakes were relocated and for well recorded events we also computed 108 fault plane solutions finally using 58 solutions the most constrained we computed regional stress field in the study area earthquake distribution shows three main seismic regions the westernmost lucanian apennines characterized by high background seismicity mostly with shallow hypocenters the easternmost below the bradano foredeep and the murge with deeper and more scattered seismicity and finally the more isolated and sparse seismicity localized in the sila range and in the offshore area along the northeastern calabrian coast focal mechanisms computed in this work are in large part normal and strike slip solutions and their tensional axes t axes have a generalized ne sw orientation the denser station coverage allowed us to improve hypocenters determination compared to those obtained by using only rsnc data for a better characterization of the crustal and subcrustal seismicity in the study area

coherent structures in the flow field around a circular cylinder with scour hole large eddy simulation les and laboratory flume visualizations were used to investigate coherent structures present in the flow field around a circular cylinder located in a scour hole the bathymetry corresponds to equilibrium scour conditions and is fixed in les the flow parameters in the simulation correspond to the experimental conditions in which the approach flow is fully turbulent detailed consideration is given to the interaction of the horseshoe vortex hv system within the scour hole with the detached shear layers formed from the cylinder and the near bed turbulence it is found that the overall structure of the hv system varies considerably in space and time though a large relatively stable primary necklace vortex is present at practically all times inside the scour hole the simulation captures the presence of bimodal chaotic oscillations inside the hv system as well as the sharp increase in the resolved turbulent kinetic energy levels and pressure fluctuations reported in prior experimental investigations high levels of the mean bed shear stress are observed beneath the primary necklace vortex especially over the region where the bimodal oscillations are strong as well as beneath the small junction vortex at the base of the cylinder it is also found that the detachment and advection of patches of vorticity from the downstream part of the legs of the necklace vortices can induce large instantaneous bed shear stress values when the critical bed shear stress value for sediment entrainment on a flat surface is adjusted for bed slope effects the les simulation correctly predicts that the distribution of the mean bed shear stress is consistent with equilibrium scour conditions

three dimensional velocity structure in northern california coast ranges from inversion of local earthquake arrival times abstract the three dimensional p wave velocity structure in the upper crust in the northern california coast ranges from santa rosa to ukiah is obtained by simultaneous inversion of local earthquake and refraction travel time data for velocity and hypocentral parameters in this region where there are lateral heterogeneities the three dimensional inversion provides important results not found in two dimensional refraction studies the medium is parameterized with velocities at the intersections gridpoints of a nonuniform three dimensional grid travel times are calculated with approximate ray tracing along arcuate paths which are reasonable for lateral distances less than 45 km inversions with 5 to 10 and 2 to 3 km gridspacing achieved 80 per cent decreases in data variance the inversion with 2 to 3 km gridspacing reduced the rms residual level to approximately the level of timing error anomalously low velocities to at least 6 km depth are found along the maacama and healdsburg rodgers creek hrc fault zones the low velocity region is widest at the en echelon junction of the maacama and hrc fault zones low velocities are associated with the clear lake basin where there is a thick sequence of volcanics interbedded with sedimentary deposits there is a high velocity body located southeast of the geysers between the maacama and collayomi fault zones which may be associated with igneous intrusives or high grade metamorphism related to an underlying inferred partial melt body modeled in previous teleseismic travel time studies there is some indication in the vapor dominated geothermal reservoir of lower velocities relative to surrounding water saturated rock as has been shown in some laboratory experiments hypocenter locations obtained in the inversion show little variation from hypocenters obtained through inversion for one dimensional velocity model and station corrections for the inversion with 2 to 3 km gridspacing however some groups of events become more tightly clustered

neo alpine structural evolution and present day tectonic activity of the eastern southern alps the case of the ravne fault nw slovenia abstract the ravne fault is an actively propagating nw se trending dextral strike slip fault in the julian alps of nw slovenia which has been responsible for two moderate sized earthquakes in the last decade strike slip displacements on moderate steep fault planes are responsible for the recent seismic activity that is confined to shallow crustal levels the fault is growing by interaction of individual right stepping fault segments and breaching of local transtensional step over zones the fault geometry is controlled by the original geometry of the nw se trending thrust zone modified by successive faulting within the fault zone in the modern n directed maximum horizontal stress regime the segmented fault is lengthening by active growth at the fault s nw end the spatial distribution of earthquake clusters shows that activity on strike slip segments and thrust faults is contemporaneous detailed analysis of the spatial pattern of earthquake events and surface fault geometries suggests that for earthquakes of similar magnitudes and similar fault kinematics the deciding factor for whether an earthquake rupture will breach a step over zone is the relationship between the lengths of individual neighbouring fault segments and fault separation distances in the step over zones the ravne fault represents an example of a tectonic structure that lies in an area subjected to multiple tectonic events under different regional stress conditions at epicentral depths the fault system is accommodating recent strain along newly formed fault planes whereas in upper parts of the crust the activity is distributed over a wider deformation zone that includes reactivated brittle thrust faults

quantifying early miocene in sequence and out of sequence thrusting at the alpine carpathian junction a detailed reconstruction of late oligocene and early miocene thrusting at the leading edge of the east alpine fold thrust belt is achieved from well data seismic and interpretative cross sections data are used for constraining the paleogeographic positions of the alpine thrusts quantifying in sequence out of sequence thrust distances assessing the timing of thrust propagation from structurally higher units into more external ones and estimating thrust velocities results are depicted in five palinspastic maps for time slices between 26 ma and 16 ma the termination of foreland propagating thrusting at the alpine front is apparently controlled by the subcrop topography of the european basement which includes a major recess in the east leading to a diachronic along strike termination of foreland propagating thrusting with younger thrust ages and higher in sequence thrust distances in the east early locking of foreland propagating thrusting in the west causes prominent out of sequence thrusts which add to the in sequence thrust distances there continuing consecutive detachment of foreland units in the east occurs at rather fast propagation velocities with time intervals between foreland thrust propagations ranging between 0 1 and 0 7 ma the resulting increase of in sequence thrust distances from west to east is balanced by out of sequence thrusts in the west the total amount of late oligocene to early miocene thrusting is quantified with a minimum of 51 km average thrust velocities range between 4 6 and 5 2 mm yr this rate refers to the movement of the basal thrust at the leading edge of the fold thrust belt which occurs contemporaneous with the eastward lateral extrusion of the eastern alps in the hinterland

flow field complexity and design estimation of pier scour depth sixty years since laursen and toch abstractthis paper written to celebrate the 60th anniversary of the journal of hydraulic engineering presents a structured contemporary approach to scour depth estimation that matches design met

high frequency attenuation of shear waves in the southeastern alps and northern dinarides summary we investigated the high frequency attenuation of s waves in the southeastern alps and northern external dinarides using waveforms from 331 earthquakes 3 0 mw 6 5 the spectral decay parameter k was computed using 1345 three component high quality records collected by the italian strong motion network ran and by the short period seismometric network of northeastern italy nei in the period 1976 2007 weak motion data from 11 stations of the nei network and strong motion data collected by five accelerometers of the ran were analysed the k parameter was estimated in the 0 250 km distance range in a frequency band extending from the corner frequency of the event up to 25 or 45 hz using the amplitudeaccelerationfourierspectraofs waves theobservedrecord to recordvariabilityof k was modelled by applying a generalized inversion procedure using both parametric and nonparametric approaches our results evidence that k is independent on earthquake size while it shows both site and distance dependence stations of the nei network present the same increase of k with epicentral distance re and show values of the zero distance k parameter k0 s between 0 017 and 0 053 s for the whole region the k increase with distance can be describedthroughalinearmodelwithslopedk dre 1 4 0 1 10 4 skm 1 assumingan average s wave velocity 3 34 km s 1 between 5 and 15 km depth we estimate an average frequency independent quality factor qi 2140 for the corresponding crustal layer the non parametric approach evidences a weak positive concavity of the curve that describes the k increase withre at about 90 km distance this result can be approximated through a piecewise linear function with slopes of 1 0 10 4 and 1 7 10 4 sk m 1 in accordance with a three layers model where moving from the intermediate to the bottom layer both qi and decrease two regional dependences were found data from earthquakes located westward to the nei network evidence weaker attenuation properties probably because of s wave reflections from different parts of the moho discontinuity under the eastern po plain at about 25 30 km depth while earthquakes located eastward in western slovenia where the moho deepens up to 45 50 km evidence a higher attenuation moreover the k estimates obtained with data from earthquakes located in the area of the 1998 mw 5 7 and 2004 mw 5 2 kobarid events are 0 017 s higher than the values predicted for the whole region probably because of the high level of fracturing that characterizes fault zones the comparison between measured and theoretical values of k computed at a few stations with available s wave velocity profiles reveals that the major contribution to the total k0 s is due to the sedimentary column from surface to 800 m depth the hard rock section contribution is limited to 0 005 s in accordance with a maximum contribution of 0 010 s predicted by the non parametric inversion

study of the generation and propagation of internal waves in the strait of gibraltar using a numerical model and synthetic aperture radar images of the european ers 1 satellite a weakly nonhydrostatic two layer numerical model based on the boussinesq equations is presented which is capable of describing among others the generation and propagation of nonlinear weakly dispersive internal waves in the strait of gibraltar the model depends on one space coordinate only but it retains several features of a fully three dimensional model by including a realistic bottom profile a variable channel width and a trapezoidal channel cross section the nonlinear primitive boussinesq equations include horizontal diffusion bottom friction and friction between the two water layers the model is driven by a height difference of the mean interface depth between the atlantic and the mediterranean boundaries and by semidiurnal tidal oscillations of the barotropic transport the model presented in this paper describes 1 the mean and tidal flow in the strait of gibraltar 2 the variation of the depth of the interface during a tidal cycle 3 the generation of strong depressions of the interface at the western sides of the spartel sill and the camarinal sill 4 the generation of strong eastward propagating internal bores and 5 their disintegration into trains of internal solitary waves the surface convergence patterns associated with depressions of the interface at the camarinal sill internal bores and internal solitary waves are calculated and compared with roughness patterns visible on synthetic aperture radar sar images of the first european remote sensing satellite ers 1 in total 155 ers 1 sar scenes from 94 satellite overflights over the strait of gibraltar which were acquired in the period from january 1992 to march 1995 have been analyzed it is shown that the proposed model is capable of explaining the observed temporal and spatial evolution of surface roughness patterns associated with eastward propagating internal waves inside the strait of gibraltar as well as the observed east west asymmetry of the internal wave field

a natural and controlled source seismic profile through the eastern alps transalp abstract the combined passive and active seismic transalp experiment produced an unprecedented high resolution crustal image of the eastern alps between munich and venice the european and adriatic mohos em and am respectively are clearly imaged with different seismic techniques near vertical incidence reflections and receiver functions rfs the european moho dips gently southward from 35 km beneath the northern foreland to a maximum depth of 55 km beneath the central part of the eastern alps whereas the adriatic moho is imaged primarily by receiver functions at a relatively constant depth of about 40 km in both data sets we have also detected first order alpine shear zones such as the helvetic detachment inntal fault and sub tauern ramp in the north apart from the valsugana thrust receiver functions in the southern part of the eastern alps have also observed a north dipping interface which may penetrate the entire adriatic crust adriatic crust interface aci deep crustal seismicity may be related to the aci we interpret the aci as the currently active retroshear zone in the doubly vergent alpine collisional belt

topographic effect on oblique internal wave wave interactions based on a variable coefficient kadomtsev petviashvili kp equation the topographic effect on the wave interactions between two oblique internal solitary waves is investigated in the absence of rotation and background shear the model set up featuring idealised shoaling topography and continuous stratification is motivated by the large expanse of continental shelf in the south china sea when the bottom is flat the evolution of an initial wave consisting of two branches of internal solitary waves can be categorised into six patterns depending on the respective amplitudes and the oblique angles measured counterclockwise from the transverse axis using theoretical multi soliton solutions of the constant coefficient kp equation we select three observed patterns and examine each of them in detail both analytically and numerically the effect of shoaling topography leads to a complicated structure of the leading waves and the emergence of two types of trailing wave trains further the case when the along crest width is short compared with the transverse domain of interest is examined and it is found that although the topographic effect can still modulate the wave field the spreading effect in the transverse direction is dominant

local earthquake tomography with the inclusion of full topography and its application to kīlauea volcano hawai i abstract we develop a new three dimensional local earthquake tomography algorithm with the inclusion of full topography letft we present both synthetic and real data tests based on the p and s wave arrival time data for k lauea volcano in hawai i a total of 33 768 events with 515 711 p picks and 272 217 s picks recorded by 35 stations at the hawaiian volcano observatory are used in these tests the comparison between the new and traditional methods based on the synthetic test shows that our new algorithm significantly improves the accuracy of the velocity model especially at shallow depths in the real data application the p and s wave velocity models of k lauea show several intriguing features we observe discontinuous high vp 7 0 km s and vs 3 9 km s zones at 5 14 km depth below k lauea caldera its east rift zone erz and the southwest rift zone which may represent consolidated intrusive gabbro ultramafic cumulates at k lauea caldera vp and vs decrease from 3 9 km s and 2 6 km s from the surface to 3 7 km s and 2 3 km s at 2 km depth we resolve a high vp zone 7 0 km s at 5 14 km depth and high vs zone 3 9 km s at 5 11 km depth this high vp and vs zone extends to the north of the erz at 5 10 km depth and to the upper erz at 8 12 km depth in the hilina fault system there is a high vp layer 7 0 km s at 4 6 km depth and a low vp body of 5 7 km s at 6 11 km depth the high vp layer could be associated with the intrusive ultramafic gabbro sills the velocity contrast on the north and south sides of the koa e fault system indicates that the intrusive activities mainly occur to the north of the fault our new letft method performs well in both the synthetic and real data tests and we expect that it will reveal more robust velocity structures in areas with larger topographic variations

3d flow and sediment dynamics in a laboratory channel bend with and without stream barbs abstracta series of laboratory flume experiments were performed to study the effect of stream barbs on flow field dynamics and sediment erosion in a 135 mobile bed channel bend stream barbs also known as spur dikes or submerged groynes are low profile linear rock features that redirect high velocity flow away from the outer bank of channel bends unlike emergent groynes the submerged nature of these structures creates a unique combination of horizontal shear plunging type flow and vertical shear at the groyne tip spatially dense high frequency velocity data were collected and analyzed to describe the pattern and magnitude of three dimensional 3d velocity throughout the bend and in the vicinity of the stream barbs this paper demonstrates that the outer bank region particularly between barbs may still be at risk of erosion or even increased erosion greater than the same case without barbs if stream barbs generate excessive secondary velocities because of their size and layout that are op

neogene quaternary tectonic stratigraphy of the eastern southern alps ne italy abstract in order to reconstruct the neogene quaternary tectonic stratigraphy of the eastern southern alps the late tortonian lower pleistocene foredeep clastic sequences cropping out in the veneto and friuli piedmont areas have been extensively investigated focusing on the contractional features observed in the frequent conglomerate layers pitted pebbles the eastern southern alps is the result of a typical polyphase tectonic activity initiated in late oligocene characterised by the occurrence of several non coaxial stress regimes based on careful analyses of the pebbles surfaces shape and orientation of the indented features and following a systematic and statistical approach the mean orientation of the maximum compressive stress axis 1 has been obtained for more than 30 sites of measurements along the ca 120 km long investigated piedmont area the affected lithostratigraphic units and the orientation pre versus post tilting of the stereonets density peaks make it possible to recognize four distinct deformational events and characterize them in terms of mean 1 direction and timing late tortonian 1 313 00 late messinian early pliocene 338 04 late pliocene 314 03 and early middle pleistocene 160 03 the tectonic stratigraphy of the eastern southern alps during the last ca 10 ma shows the occurrence of several variations of the stress field characterized by a repeated oscillation of the 1 axis between an nnw sse and nw se directions twist tectonics taking also into account literature data about older deformational events chattian burdigalian and serravallian tortonian we analyse the neogene quaternary tectonic evolution in the frame of the central mediterranean realm and compare it with the convergence direction between the adria africa and europe lithospheric plates we show that compressional directions within the eastern southern alps are basically governed by the remote plate convergence though since late messinian the approaching northern apennines started to play a crucial role within the investigated area alternating short lived phases 1 2 ma of coupling and decoupling along the basal detachment of the apennines accretionary wedge probably caused temporary perturbations of the local stress field and complex accommodation structures in this region of ongoing crustal collision

seismic properties of the upper crust in the central friuli area northeastern italy based on petrophysical data abstract the compressional and shear wave velocities have been measured at room temperature and pressure up to 450 mpa on 5 sedimentary rock samples representative of the most common lithologies of the upper crust in the central friuli area northeastern italy at 400 mpa confining pressure the triassic dolomitic rock shows the highest velocities vp 7 km s vs 3 6 km s the jurassic and triassic limestones samples intermediate velocities vp 6 3 s vs 3 5 km s and the cenozoic and paleozoic sandstones the lowest velocities vp 6 15 km s vs 3 35 km s the paleozoic sandstone sample is characterized by the strongest anisotropy 10 and significant birefringence 0 2 km s is found only on the cenozoic sandstone sample we elaborated the synthetic profiles of seismic velocities density elastic parameters and reflection coefficient related to 4 one dimensional geological models extended up to 22 km depth the synthetic profiles evidence high rheological contrasts between triassic dolomitic rocks and the soft sandstones and the jurassic limestones the vp profiles obtained from laboratory measurements match very well the in situ vp profile measured by sonic log for the limestones and dolomitic rocks supporting our one dimensional modelling of the calcareous carbonatic stratigraphic series the vp and vs values of the synthetic profiles are compared with the corresponding ones obtained from the 3 d tomographic inversion of local earthquakes the laboratory vp are generally higher than the tomographic ones with major discrepancies for the dolomitic lithology the comparison with the depth location of seismicity reveals that the seismic energy is mainly released in correspondence of high contrast rheological boundaries

present state of tectonic stress of the friuli area eastern southern alps stress orientations are determined for the friuli area from focal mechanisms using the inversion technique of gephart and forsyth 1984 the data consist of 244 fault plane solutions selected for the period 1988 1995 where the data coverage was poor this period was extended to 1978 1996 local magnitude ranges from 2 0 to 4 3 and the depths extend from 4 to 16 km the friuli area is subdivided into five seismotectonic zones on the basis of tectonic characteristics seismic activity and focal mechanisms and for each zone a stress tensor is determined the results show that the active tectonic stress in the friuli area is heterogeneous and conditioned by the complex structural pattern which is characterized by two indented tectonic wedges the western and central parts of the area are mainly affected by a compressional state of stress while in the eastern part a strike slip state of stress prevails the orientation of the principal stresses varies from the western to the eastern part of the area and differences are also noticeable with depth in the central part of the friuli area the maximum compressional stress is n s trending at shallow depths 10 km changing to nw se at deeper levels the maximum compressional stress is nw se oriented in the western part while in the eastern part it is n s oriented

normal faults and thrusts reactivated by deep fluids the 6 april 2009 mw 6 3 l aquila earthquake central italy 1 on 6 april 2009 a mw 6 3 earthquake occurred in the central apennines italy damaging the city of l aquila and the surrounding country we relocate the october 2008 to 6 april 2009 foreshocks and about 2000 aftershocks occurred between 6 and 30 april 2009 by applying a double difference technique and determine the stress field from focal mechanisms the events concentrate in the upper 15 km of the crust three main nw se to nnw sse striking 30 45 and 80 90 dipping faults were activated during the seismic sequence among these a normal fault and a thrust were reactivated with dip slip movements in response to ne sw extension the structural maturity of the seismogenic fault system is lower than that displayed by other systems in southern apennines because of the lower strain rate of the central sector of the chain with respect to the southern one vp vs increases progressively from october 2008 to the 6 april 2009 main shock occurrence along a nw se strike because of an increment in pore fluid pressure along the fault planes pore pressure diffusion controls the space time evolution of aftershocks a hydraulic diffusivity of 80 m2 s 1 and a seismogenic permeability of about 10 12 m2 suggest the involvement of gas rich co2 fluids within a highly fractured medium suprahydrostatic high fluid pressure about 200 mpa at 10 km of depth within overpressurized traps bounded by preexisting structural and or lithological discontinuities at the lower upper crust boundary are required to activate the april 2009 sequence traps are the storage zone of co2 rich fluids uprising from the underlying about 20 km deep metasomatized mantle wedge these traps easily occur in extensional regimes like in the axial sector of apennines but are difficult to form in strike slip regimes where subvertical faults may cross the entire crust in the apennines fluids may activate faults responsible for earthquakes up to mw 5 6 deep fluids more than tectonic stress may control the seismotectogenesis of accretionary wedges

full moment tensor retrieval for two earthquake swarms at the alps dinarides junction summary we present the results of the analysis for the seismic source tensor of all events with m d 3 0 belonging to the moggio udinese swarm 1988 february eight events analysed and of the three events of the swarm that occurred between 1993 july 22 and 26 in the tricesimo area the latter sequence is particularly relevant for the assessment of seismic risk of friuli northeast italy since it is close to the densely populated area of udine we use a waveform inversion algorithm which allows us to retrieve the moment tensor rate functions mtrfs that can be factored into a moment tensor and a source time function stf from the orientation of the p axis and of the nodal planes we can hypothesize that the moggio udinese swarm p axis orientated globally between southeast northwest and east west reflects the influence of both the southeastern alpine and external dinaric stress field while in the tricesimo swarm in which the p axis orientations varies between southeast northwest and north south the southeastern alpine stress field seems to act on faults oriented southeast northwest belonging to the external dinaric system

coherent structure dynamics in turbulent flows past in stream structures some insights gained via numerical simulation large scale coherent vortical structures in natural streams and rivers dominate flow and transport processes and impact the stability of stream banks the diversity and abundance of organisms and the quality of running waters in aquatic ecosystems thus understanding and being able to model the dynamics of energetic coherent structures in such flows at ecologically relevant scales are crucial prerequisites for developing a science based ecosystem restoration framework we review recent progress toward the development of coherent structure resolving csr computational fluid dynamics techniques based on hybrid urans les modeling strategies for simulating turbulent flows in open channels with hydraulic structures csr simulations of the turbulent horseshoe vortex thsv past bed mounted piers explained the physical mechanism leading to the experimentally documented bimodal velocity fluctuations of the vortex and underscored the importance of the reynolds number as a key parameter governing the thsv dynamics simulations of high reynolds number flows past surface piercing groynelike structures in open channels revealed the complexity of the recirculating region at the upstream face of the groyne underscored the interaction of the flow in this region with the energetic shear layer shed from the point of separation at the upstream side wall and demonstrated the importance of flow depth in the vorticity dynamics of such flows the paper also identifies areas for future work and modeling challenges that need to be addressed for the computational tools to be able to accurately predict flow and transport processes in real life aquatic environments

heat production and thermal conductivity of rocks from the pikwitonei sachigo continental cross section central manitoba implications for the thermal structure of archean crust the pikwitonei and sachigo subprovinces of central manitoba provide a cross sectional view of the superior province crust in cross section the upper to mid level crust is composed of synformal greenstone belts surrounded by tonalitic gneisses both of which are intruded by granitoid plutons this crustal structure persists downward into the granulite facies where keels of the greenstone belts can be found to constrain thermal models of the crust we measured heat production and thermal conductivity in 60 rocks from this terrain using standard gamma ray spectrometry and divided bar techniques large vertical and lateral heterogeneities in heat production in the upper crust are evident heat production is high in granites and metasedimentary rocks intermediate in tonalite gneisses and low in the portions of greenstone belts dominated by mafic meta igneous rocks in the deeper granulite facies rocks heat production decreases by a factor of two in the tonalitic gneisses and remains low in the high grad

simulations of internal solitary wave interactions with mesoscale eddies in the northeastern south china sea abstractwith the combined analysis of synthetic aperture radar image and satellite altimeter data collected in the northeastern south china sea scs this study found one type of distorted phenomenon of internal solitary wave isw with the long front caused by the oceanic mesoscale eddy motivated by these satellite observations the authors carried out numerical experiments using the fully nonhydrostatic and nonlinear mitgcm to investigate the perturbation of isws by an isolated cyclonic or anticyclonic eddy the results show that the isw front is distorted by these oceanic eddies due to the retardation and acceleration effects at their two sides the isw energy along the front is focused onto scattered from the wave fragment where a concave convex pattern is formed and the previously accumulated energy in the focusing region is gradually released after the isw propagates away from the eddies the isw amplitude is modulated greatly by the eddies due to the energy redistribution along the front se

parameterization of mean residence times in idealized rectangular dead zones representative of natural streams abstractthree dimensional reynolds averaged navier stokes modeling validated against experimental data is used to parameterize the flow features and time scales in idealized rectangular cavities for a wide range of width to length ratios 0 4 w l 1 1 and reynolds number based on the depth 5 000 rd 20 300 representative of isolated dead zones in small natural streams the flow features for this parameter range are similar to open cavity flows and consist of a mixing layer spanning the entire length of the dead zone together with a single main recirculation region the langmuir time scale ratio of dead zone volume to discharge based on the assumption of a well mixed dead zone is found to be a function of the mean rotation time scale inverse of average rotation rate within the dead zone the momentum thickness of the upstream boundary layer and the dead zone width the entrainment coefficient used to relate the exchange velocity to the average free stream velocity is shown to be directly related

3d velocity structure around the source area of the 1999 chi chi taiwan earthquake before and after the mainshock 3d v p and v p v s models for the source area before and after the chi chi earthquake are derived from a tomographic inversion of seismic travel time data from the taiwan central weather bureau seismic network cwbsn resulting 3d velocity models reveal a strong lateral variation in the crust particularly at a depth range of 5 to 25 km along the trend of the dipping chelungpu thrust in general low v p and high v p v s anomalies are found in and around the source volume of the chi chi earthquake a volume centered around the entire 100 km 40 km chelungpu rupture surface we pay special attention to the crustal properties and their changes due to the chi chi event and the association of the crustal anomalies with seismicity combining the results with those of other geological and geophysical surveys the crustal anomalies are interpreted as images of a highly fractured and fluid filled chi chi source region fluid overpressure is known to reduce the strength of the fault zone and in this case may have initiated the nucleation of the chi chi earthquake the v p models obtained before and after the chi chi event show some interesting heterogeneities regions of low v p anomaly appear to have further expanded with the occurrence of the chi chi earthquake the v p v s model shows high anomalies near the source rupture especially near where the rupture is believed to have nucleated after the chi chi event the v p v s model shows a substantial change that may reflect an outward shift of the fluid filled fractured source region this shift is shown by a general expansion in v p v s anomalies to a broader region e g where two intensive aftershock clusters occurred and a significant v p v s reduction to more normal values near the chelungpu rupture we attribute these changes in v p and v p v s anomalies as well as the expansion and shift of the anomalous regions to be a response to the localized stress change caused by the slip of the chi chi rupture the location of the seismic events is correlated with that of the crustal v p and v p v s anomalies large events appear to occur in the transition zones of both v p and v p v s anomalies this finding may be of use in the identification of weakened crustal regions in a seismic zone thus suggesting where impending large earthquakes are likely to occur all input data and initial and final models of this article are given as electronic files in the cd attached to the end of this issue

transport of suspended sediments under the influence of bank macro roughness river restoration works often include measures to promote morphological diversity and enhance habitat suitability one of these measures is the creation of macro roughness elements such as lateral cavities and embayments in the banks of channelized rivers however in flows that are heavily charged with fine sediments in suspension such as glacier fed streams and very low gradient reaches of large catchment rivers these lateral cavities may trap these sediments consequently the morphological changes may be affected and the functionality of the restoration interventions may be compromised herein we analyse the influence of these macro roughness elements on the transport of fine sediments in the main channel laboratory tests with uniform flow charged with sediments in a channel with banks equipped with large scale rectangular roughness elements were carried out the laboratory experiments covered a wide range of rectangular cavity geometrical configurations and shallowness ratios the influence of key parameters such as flow shallowness geometric ratios of the cavities and initial sediment concentration was tested surface particle image velocimetry sediment samples and temporal turbidity records were collected during the experiments the amount of sediments captured by the cavities the temporal evolution of the concentration of sediments in suspension and the flow hydrodynamics are cross analysed and discussed it is shown that the trapping efficiency of the macro roughness elements is a clear function of the channel geometry and the shallowness of the flow

three dimensional vp and vp vs models of the upper crust in the friuli area northeastern italy summary 3 d images of p velocity and p t os velocity ratio have been produced for the upper crust of the friuli area northeastern italy using local earthquake tomography the data consist of 2565 p and 930 s arrival times of high quality the best fitting v p and v p v s 1 d models were computed before the 3 d inversion v p was measured on two rock samples representative of the investigated upper layers of the friuli crust the tomographic v p model was used for modelling the gravity anomalies by converting the velocity values into densities along three vertical cross sections the computed gravity anomalies were optimized with respect to the observed gravity anomalies the crust investigated is characterized by sharp lateral and deep v p and v p v s anomalies that are associated with the complex geological structure high v p v s values are associated with highly fractured zones related to the main faulting pattern the relocated seismicity is generally associated with sharp variations in the v p v s anomalies the v p images show a high velocity body below 6 km depth in the central part of the friuli area marked also by strong v p v s heterogeneities and this is interpreted as a tectonic wedge comparison with the distribution of earthquakes supports the hypothesis that the tectonic wedge controls most of the seismicity and can be considered to be the main seismogenic zone in the friuli area

seismotectonic study of the friuli italy area based on tomographic inversion and geophysical data abstract the upper crustal structure of the friuli area involved in the seismic sequence which started on may 6 1976 main shock m l 6 4 is investigated together with the distribution of seismicity in order to define the main seismotectonic features three dimensional p velocity modelling is obtained by tomographic techniques using local earthquakes recorded by the seismic network of the osservatorio geofisico sperimentale lateral velocity variations and velocity inversions are related to structural heterogeneities the shortened and thrusted sedimentary cover is detached from the basement the 3 d velocity structure shows a southward verging thrusted wedge basement below 5 km depth analysis of the distribution of earthquakes together with three dimensional velocity modelling shows that active faulting is represented by north dipping thrusts uplifting the basement wedge this high velocity block forms the main seismogenic zone

modeling surface gps velocities in the southern and eastern alps by finite dislocations at crustal depths abstract the indentation of the adria plate into the southern and eastern alps is an ongoing collisional process accompanied by seismicity surface and rock uplift and lateral escape we present a 3d quantitative description of the process by combining gps and structural data with an elastic dislocation model horizontal velocities of 70 austrian and italian permanent gps stations in the eastern and southern alps serve as boundary condition on the free surface of an elastic half space containing six rectangular faults each with a uniform slip rate the geometry of the rectangular faults and the slip rate vector are constrained by least squares taking into account the structural setting of the area and the geographic distribution of the velocity data we find that the surface velocities of the order of some mm yr require reverse north side of the tauern window transpressional giudicarie north alpine wrench corridor pustertal dinarides and normal brenner fault slips ranging from 10 to 30 mm yr at crustal depths the regional stress pattern computed from fault plane solutions agrees with the principal directions of our rectangular fault planes the model although constrained by horizontal velocities only predicts a pattern of vertical motion which qualitatively agrees with known phenomena such as the surface uplift in the tauern window area of the order of up to few mm yr if the heat on the shearing fault planes is removed mostly by upwards diffusion the absence of large heat anomalies on the earth s surface suggests for nominal geotherms shear stresses and concentration of subcrustal radiogenic elements that the time of initiation of the slip dates to pliocene hence more recent than late oligocene miocene time of collision of the adria indenter