deep seated gravitational slope deformations related landslides and tectonics abstract deep seated gravitational slope deformations and their relationships with tectonic deformation of rocks is considered to examine the viewpoint of tectonics as a causative factor in slope deformation first a distinction is made between the different types of deep seated gravitational slope deformation then the geomorphological and structural effects of the different macrostructural deformations induced by tectonics on the scale of the whole deforming ridge is briefly discussed finally some case studies that represent either verified or possible cases of gravity deformation in response to tectonic activity are used as illustration

paraglacial rock slope stability glaciation and deglaciation along with their associated climatic and non climatic processes modify slope stresses and influence slope stability paraglacial slope failures are those that are a part of or influenced by the transition from glacial conditions to non glacial conditions gravitational failure of rock slopes is a primary and dominant process of slope evolution in mountainous terrain and is the subject of this paper which 1 reviews the approaches taken for researching paraglacial rock slope failure patterns and processes 2 summarises the spatial and temporal patterns of post glacial failures 3 assesses the factors influencing slope stability during glaciation and deglaciation 4 explores some of the applications of paraglacial research and 5 highlights some of the outstanding issues to be resolved and provides recommendations for terminology relating to paraglacial slope processes

extensive deformations of rock slopes in southern coast mountains southwest british columbia canada extensive deformations of mountain slopes occur in crystalline intrusive rocks in the southern coast mountains of british columbia typical morphological evidence of slope movement includes extensive systems of tension cracks grabens and antislope scarps collectively referred to here as linears these landforms involve displacements along penetrative joints observed in surface exposures kinematic tests on rock structural data indicate that the observed patterns of linears are generally consistent with the feasible gravitational movements along the dominant discontinuities most sites indicate sliding as the most likely initial mode of movement followed by or accompanied by toppling and toppling induced sliding movements and do not support the view that linears are the traces of active faults

on the use of the radon transform to estimate longshore currents from video imagery abstract larnier s almar r cienfuegos r lejay a 2014 on the use of the radon transform to estimate longshore currents from video imagery in green a n and cooper j a g eds proceedings 13th international coastal symposium durban south africa journal of coastal research special issue no 70 pp 023 028 issn 0749 0208 in nearshore applications the estimation of longshore currents is of primary importance since it controls the alongshore sediment transport and coastal evolution direct estimation of longshore currents using in situ instruments is difficult and costly especially under highly energetic wave climates low cost remote sensing systems based on video observations constitute a promising alternative when the drifting sea foam left after the passage of breaking waves is visible in this paper we describe a method based on longshore timestacks that necessitates less data than approaches using the full video frames our approach uses the radon transform applied on the tim

interferometric daylight seismic imaging summary claerbout s daylight imaging concept is generalized to a theory of interferometric seismic imaging ii interferometric seismic imaging is defined to be any algorithm that inverts correlated seismic data for the reflectivity or source distribution as examples we show that ii can image reflectivity distributions by migrating ghost reflections in passive seismic data and generalizes the receiver function imaging method used by seismologists interferometric seismic imaging can also migrate free surface multiples in common depth point cdp data and image source distributions from passive seismic data both synthetic and field data examples are used to illustrate the different possibilities of ii the key advantage of ii is that it can image source locations or reflectivity distributions from passive seismic data where the source position or wavelet is unknown in some cases it can mitigate defocusing errors as a result of statics or an incorrect migration velocity the main drawback with ii is that severe migration artefacts can be created by partial focusing of virtual multiples

video estimation of subaerial beach profiles abstract a technique is presented that allows estimation of the subaerial beach profile using video imagery using either a shadow from a pole or the light from a narrow slit a line can be drawn across the beach at a known origin and angle when viewed from the longshore direction the line will appear as a visible beach profile that can be digitized from the image and the ground coordinates of the profile uniquely determined the theoretical pixel vertical footprint is about one thousandth of the range from the camera or for a typical camera about 10 cm at the 100 m range accuracies can be up to 1 2 pixel or 5 cm at this range a field test using a fire hose as a proxy for the shadow proved the technique with an average accuracy of 68 of the theoretical footprint size being found the success of this technique suggests that profile data may be routinely collected using an automated system without the need for a survey team thus allowing the ready collection of long time series for climatological studies

ocean wave dispersion surface measured with airborne ir imaging system image sequences of the ocean have been collected at long range and low grazing angle with an airborne infrared system the images are geographically registered and 3d frequency wavenumber spectra are calculated and shown to have a strong 2d dispersion surface that is characteristic of wind waves and swell wave directions compare well with in situ measurements and their speeds are consistent with the water depth the authors conclude that temporal sequences of ir images acquired from long distance can provide information for extracting surface wave parameters

longshore surface currents measured by doppler radar and video piv techniques mean longshore surface currents within the surf zone were measured using two remote sensing techniques microwave doppler radar and optical video doppler radar relies on small scale surface roughness that scatters the incident electromagnetic radiation so that velocities are obtained from the doppler shift of the backscattered radiation video relies on texture and contrast of scattered sunlight from the sea surface and velocity estimates are determined using particle imaging velocimetry piv this paper compares video piv and doppler radar surface velocities over a 1 km alongshore by 0 5 km cross shore area in the surf zone of a natural beach the two surface velocity estimates are strongly correlated r2 ges 0 79 over much of the surf zone estimates differ at the outer edge of the surf where strong breaking is prevalent with radar estimated velocities as much as 50 below the video estimates the radar and piv velocities at particular locations in the surf zone track each other well over a 6 h period showing strong modulations in the mean alongshore flow occurring on 10 20 min time intervals in one case both systems observe a strong eddy like mean flow pattern over a 200 m section of coastline with the mean alongshore current changing direction at about the mid surf zone the good spatial and temporal agreement between the two remote measurement techniques which rely on very different mechanisms suggests that both are reasonably approximating the true mean longshore surface velocity

advances in swash zone research small scale hydrodynamic and sediment transport processes abstract extensive research efforts in the last decade have improved knowledge of swash zone processes this paper reviews and synthesizes from 2004 onward the research advances of small scale hydrodynamics and sediment transport processes considering field laboratory and numerical modeling efforts swash zone hydrodynamics are examined by means of shoreline motions fluid velocities pressure gradients flow structure bed shear stress friction coefficients and turbulence subsequently advances related to sediment transport mechanisms and morphological changes are described detailed descriptions of measuring techniques novel findings and the strengths and weaknesses of the different approaches are discussed the review also acknowledges the major advances in the development of instrumentation to collect highly resolved flow and sediment concentration measurements in direct proximity of the bed and the experimental framework for analyzing local dynamics on a wave by wave time scale e g dam break

nearshore bar crest location quantified from time averaged x band radar images abstract the remote sensing of the sea surface is commonly regarded as a logistically simple and cost effective way of obtaining long term years time series of nearshore sandbar location in this paper we demonstrate that similar to video imagery time exposure x band 3 cm wave length radar images contain alongshore breaking related high intensity bands that can be used to compute the location of the underlying sandbar crests analysis of time exposure x band images and bathymetric surveys collected at egmond aan zee netherlands shows that the radar based bar crest location defined as the cross shore location of maximum radar intensity differs from the in situ surveyed crest location by a distance of o 10 m this difference xradar depends linearly on the offshore water level consistent with model predictions in which the radar intensity is assumed to behave as the energy of the surface roller the model additionally suggests a dependence of xradar on the offshore wave height when the wave field across the bar is non saturated in general such wave conditions did not result in radar images with sufficient contrast to determine the bar crest location and accordingly the wave height dependence was not observed clearly in the field because of the dependence of xradar on the offshore water level time series of radar based bar crest location show artificial variability when the images are collected at different water levels various techniques for correcting this variability are discussed

numerical simulations of glacial valley longitudinal profile evolution glaciers shape alpine landscapes they broaden valley bottoms enhance local valley relief generate multiple steps overdeepen valley floors and cause tributary valleys to hang these distinctive glacial signatures result from 10 4 10 5 yr of erosion during which swings in climate drive advances and retreats of alpine glaciers we use a numerical model of glacial erosion to explore the development of the longitudinal profiles of glaciated valleys the model is driven by the past 400 k y of variable climate because both sliding speed which dictates abrasion rate and water pressure fluctuations which strongly modulate quarrying rate should peak at the equilibrium line altitude ela we expect the locus of most rapid erosion to follow the transient ela simulations of a single glacial valley show rapid flattening of the longitudinal profile inclusion of a tributary glacier creates a step immediately downvalley of the tributary junction that persists over multiple glaciations and commonly leaves the tributary valley hanging steps and overdeepenings result from an increase in ice discharge immediately below the tributary junction which is accommodated primarily by increased ice thickness and hence sliding rate the size of the step increases with the ratio of tributary to trunk ice discharge while the height of a hanging valley reflects the difference in the time integrated ice discharge in tributary and trunk valleys and therefore increases as the discharge ratio decreases

remote sensing of breaking wave phase speeds with application to non linear depth inversions abstract a number of existing models for surface wave phase speeds linear and non linear breaking and non breaking waves are reviewed and tested against phase speed data from a large scale laboratory experiment the results of these tests are utilized in the context of assessing the potential improvement gained by incorporating wave non linearity in phase speed based depth inversions the analysis is focused on the surf zone where depth inversion accuracies are known to degrade significantly the collected data includes very high resolution remote sensing video and surface elevation records from fixed in situ wave gages wave phase speeds are extracted from the remote sensing data using a feature tracking technique and local wave amplitudes are determined from the wave gage records and used for comparisons to non linear phase speed models and for non linear depth inversions a series of five different regular wave conditions with a range of non linearity and dispersion characteristics are analyzed and results show that a composite dispersion relation which includes both non linearity and dispersion effects best matches the observed phase speeds across the domain and hence improves surf zone depth estimation via depth inversions incorporating non linearity into the phase speed model reduces errors to o 10 which is a level previously found for depth inversions with small amplitude waves in intermediate water depths using linear dispersion considering the controlled conditions and extensive ground truth this appears to be a practical limit for phase speed based depth inversions finally a phase speed sensitivity analysis is performed that indicates that typical nearshore sand bars should be resolvable using phase speed depth inversions however increasing wave steepness degrades the sensitivity of this inversion method

energy density directional spectra of a nearshore wave field measured by interferometric synthetic aperture radar the nearshore wave field within monterey bay california is studied using remote sensing imaging by an interferometric synthetic aperture radar insar and simultaneous ground based measurements it is shown that insar imagery of the ocean surface offers some advantages over conventional synthetic aperture radar because of the direct imaging mechanism of insar quantitative information about the complicated wave field can be obtained the insar derived directional energy density spectra and the corresponding ground based spectra compare well

microwave radar cross sections and doppler velocities measured in the surf zone 1 the relationship between microwave imaging radar measurements of fluid velocities in the surf zone and shoaling breaking and broken waves is studied with field observations normalized radar cross section nrcs and doppler velocity are estimated from microwave measurements at near grazing angles and in situ fluid velocities are measured with acoustic doppler velocimeters advs joint histograms of radar cross section and doppler velocity cluster into identifiable distributions the nrcs values from pixels with large nrcs and high doppler velocities 2 m s decrease with decreasing bore height to the shoreline similar to scattering from a cylinder with decreasing radius the doppler velocities associated with these regions in the histograms agree well with theoretical wave phase velocities radar and adv measurements of fluid velocities between bore crests have similarly shaped energy density spectra for frequencies above about 0 1 hz but energy levels from the radar are an order of magnitude higher than those of the adv data instantaneous interbore doppler velocities are correlated with adv measured fluid velocities but are offset by 0 8 m s this offset may be due to bragg wave phase velocities wind drift range and azimuth sidelobes the finite spatial resolution of the radar and differences between mean flows measured at the surface with radar and flows measured below the surface with advs shoaling and breaking waves measured through radar grating lobes significantly affect both the doppler velocities near the edges of the images and the scattering from the rear faces of waves causing large doppler velocities to be observed in these regions

landslides and quaternary climate changes the state of the art abstract climatic factors are considered major causes and triggers of slope instability but the palaeoclimatic implications of landslides have not yet been systematically reviewed as inferred from landslides dated to the late glacial and holocene glacial interglacial transitions are the major intervals of enhanced landsliding but the length of this interval varies between distinct types of landscapes mass movements in non glaciated temperate mountain ranges arid and tropical regions and coastal areas intensified soon after the onset of the holocene alongside the warming and wetting of the climate whereas large rock slides in areas within the limits of pleistocene glaciations mostly show a millennial scale time lag with respect to glacier withdrawal although the incidence of landslides was ubiquitous throughout the holocene the mid to late holocene transition 5 4 ka was especially favourable for the origin of landslides across distinct types of landscapes indicating a strengthened role of mass movements during the culmination phases of interglacial climate optima in addition growing evidence suggests that the enhanced activity of landslides occurred during warmer interstadial conditions which is best demonstrated in the temporal coincidence of arid zone landslides with quaternary pluvials future progress in the understanding of the relationships between landslides and quaternary climate changes should benefit from the i extension of datasets of dated landslides ii geographical expansion of dating studies to regions with a lack of chronologically determined landslides e g tropics iii improvement of landslide dating strategies involving the incorporation of independent palaeoclimatic proxies and iv wider incorporation of numerical modeling within landslide dating studies

combined observations of rock mass movements using satellite sar interferometry differential gps airborne digital photogrammetry and airborne photography interpretation 1 recent global warming through the related retreat of mountain glaciers causes a growing number of different slope instabilities requiring accurate and cost effective monitoring we investigate the potential of combined remote sensing observations from satellite and airborne microwave and optical sensors for an efficient survey of mountainous ground displacements the evolution of a paraglacial deep seated rock mass movement due to glacier retreat in the swiss alps has been observed between 1976 and 2008 with satellite synthetic aperture radar sar interferometry differential gps and airborne digital photogrammetry analysis of differential sar interferograms revealed an acceleration of the landslide from 4 cm yr in the slope parallel direction during the mid 1990s to more than 30 cm yr in the summer of 2008 differential gps surveys performed between the summers of 2007 and 2008 indicate seasonal variations of the landslide activity the photogrammetric analysis revealed no significant movement i e 1 cm yr between 1976 and 1995 and provides an overview of the total displacement between 1995 and 2006 with high spatial resolution in situ and airborne photography interpretation suggests that the landslide was activated at earliest by the end of the last glaciation but without any significant long lasting activity during the holocene and that the exponentially increasing reactivation since the 1990s is the result of ongoing debutressing of the valley flank due to the glacier retreat in combination with strong precipitation and snowmelt events we conclude that the employed remote sensing techniques complement each other well within a landslide hazard assessment procedure

directional ocean wave measurements in a coastal setting using a focused array imaging radar a unique focused array imaging doppler radar was used to measure directional spectra of ocean surface waves in a nearshore experiment performed on the north carolina outer banks radar images of the ocean surface s doppler velocity were used to generate two dimensional spectra of the radial component of the ocean surface velocity field these are compared to simultaneous in situ measurements made by a nearby array of submerged pressure sensors analysis of the resulting two dimensional spectra include comparisons of dominant wave lengths wave directions and wave energy accounting for relative differences in water depth at the measurement locations limited estimates of the two dimensional surface displacement spectrum are derived from the radar data the radar measurements are analagous to those of interferometric synthetic aperture radars insar and the equivalent insar parameters are shown the agreement between the remote and in situ measurements suggests that an imaging doppler radar is effective for these wave measurements at near grazing incidence angles

uphill facing antislope scarps in the coast mountains southwest british columbia uphill facing scarps are examined at affliction creek a glacierized area within the meager creek volcanic complex of southwest british columbia scarps occur directly downslope of tension cracks and are considered to have developed from a combination of 1 antithetic movement between partly toppled slices of rock defined by a master joint set dipping into the slope and 2 erosion of the upslope face of each tension crack leaving the downslope face prominent as an antislope scarp a kinematic test for toppling failure is described glacial erosion and rapid glacial downwasting are probable causes of toppling lichenometric data indicate significant scarp development since affliction glacier attained its maximum neoglacial dimensions about 140 yr ago dilatancy is cited as a possible mechanism for scarp stabilization

shallow water bathymetry derived from an analysis of x band marine radar images of waves image sequences of surface gravity waves are readily produced by standard marine x band radars these image sequences contain a great deal of information regarding wave parameters and their variation over an area by approaching the analysis of such data using image analysis techniques it is possible to map the variations in wave behaviour in a shallow water area wave celerity and direction can be mapped and inversion algorithms based on linear wave theory used to infer the underlying bathymetry knowledge of the period of the waves is necessary for the analysis and this can also be calculated from the radar data although there is some discrepancy between the figures derived from radar data and from an offshore s4dw instrument these discrepancies are investigated and the results presented three days of data from the holderness ii deployment during 1995 have been analysed and estimates of the bathymetry produced the calculated depths show a mean water level comparable to that read off an admiralty chart for the area and a tidal signal is also clearly superimposed on the data giving confidence in the water depths derived using this technique

retrieval of moho reflected shear wave arrivals from ambient seismic noise theoretical studies on ambient seismic noise asn predict that complete green s function between seismic stations can be retrieved from cross correlation however only fundamental mode surface waves emerge in most studies involving real data here we show that moho reflected body wave sms and its multiples can be identified with asn for station pairs near their critical distances in the short period band 1 5 s we also show that an uneven distribution of noise sources such as mining activity and wind topography interaction can cause surface wave precursors which mask weaker body wave phases

residual mechanisms and kinematics of the relict lemeglio coastal landslide liguria northwestern italy abstract the lemeglio landslide is a deep seated coastal landslide of the liguria region northeastern italy involving heterogeneous rock masses formed by miocene turbidide series whose prevalent lithology varies from sandstones to mudrocks it has been recognized since the end of the nineteenth century and characterized by a relict state of activity besides the general state of slope stability given by the current morpho climatic conditions different from those that determined its original paroxysmal evolution a residual slow kinematics of the accumulation zone still exists posing a threat to buildings and infrastructures located across the landslide foot consequently the lemeglio landslide represents a relevant case of study for advancing knowledge on residual kinematics mechanisms and hazard inherited by a relict slope mass movement phenomenon the study is based on results of several drilling campaigns and geotechnical investigations carried out mainly by the regione liguria in the unstable landslide accumulation zone moreover in this area ground deformations were assessed by inclinometer measurements and adinsar data covering two partially overlapping time spans from june 2009 to july 2011 and from january 2004 to june 2014 respectively by these data joined with field geological and geomorphological surveys an integrated and consistent landslide model was reconstructed which was used for limit equilibrium lem and finite elements modelling fem analyses among principal outcomes is the recognition by field observations stratigraphic and inclinometer data as well as slope stability modelling of a basal sheared and softened band made chiefly of remoulded mudrocks which constrains the current landslide failure surface such basal band can be considered an inherited landslide structure formed during the original paroxysmal stage of the lemeglio landslide which controls the current residual kinematics of the landslide deposits throughout the foot depending also on the coastal marine erosion acting along the landslide toe

characteristics of seismic noise fundamental and higher mode energy observed in the northeast of the netherlands we study seismic noise recorded in the northeast of the netherlands by beamforming and by using empirical green s functions obtained by seismic interfero metry from beamforming we found differences in noise directions in different fre quency bands the main source region for primary microseisms 0 05 0 08 hz is in the west northwest direction while the secondary microseisms 0 1 0 14 hz have a west southwest back azimuth furthermore we observed a fast 4 km s arrival corresponding to the rayleigh wave overtone this arrival is also in the secondary microseism band between 0 15 and 0 2 hz but has a west northwest back azimuth both arrivals in the secondary microseism band gain in strength during winter as does the average wave height in the north atlantic we measured phase velocity dispersion curves from both beamforming and noise cross correlations as well as group velocity from the latter these are then jointly inverted for an average 1d s wave model the results show how the combination of different methods leads to a more complete char acterization of the propagation modes and an improved knowledge of the subsurface especially as the group velocity measurements increase the upper frequency limit of analysis providing valuable information of the shallowest subsurface

video derived near bed and sheet flow sediment particle velocities in dam break driven swash abstract this short communication considers a video based approach to quantify near bed and sheet flow swash zone sediment particle velocities over a mobile bed in a laboratory setting and relate the profile shape to sheet thickness and a velocity that can be measured outside the sheet layer by for instance a current meter near bed high speed imagery was recorded during a dam break driven swash event in a flume with optically clear walls repeated swash events for two different median sediment sizes were tested optical current meter ocm analysis was applied to bed parallel image time stacks extracted at elevations from below the at rest bed to within the lower water column ocm results were compared to in situ velocity measurements where possible obtained with an acoustic doppler profiling velocimeter adpv ocm results compared well with adpv measurements for moderate suspended sediment concentrations based on visual observation sediment concentrations were not measured too high of a sediment concentration over saturated the image and did not provide distinct sediment particle trajectories in a consistent direction for ocm analysis this saturation occurred during uprush for both sediment sizes too little of a sediment concentration provided an inadequate number of sediment particle trajectories to track such as during flow reversal for the coarser sediment for coarser sediment backwash velocities were well resolved in ocm analysis with velocities comparing well correlation coefficient 0 8 to adpv estimates the dimensionless backwash sheet flow sediment particle velocity profile normalized by the velocity at the top of the sheet scaled with the dimensionless elevation normalized by the sheet layer thickness to the 0 62 power with 95 confidence intervals for the exponent ranging from 0 47 to 0 76

shallow crustal imaging using distant high magnitude earthquakes global phases viz seismic phases that travel through the earth s core can be used to locally image the crust by means of seismic interferometry this method is known as global phase seismic interferometry glopsi traditionally glopsi retrieves low frequency information up to 1 hz recent studies however suggest that there is high frequency signal present in the coda of strong distant earthquakes this research quantifies the potential of these high frequency signals by analysing recordings of a multitude of high magnitude earthquakes 6 4 mw and their coda on a selection of permanent usarray stations nearly half of the p pkp and pkikp phases are recorded with a signal to noise ratio of at least 5 db at 3 hz to assess the viability of using the high frequency signal the second half of the paper highlights two case studies first a known sedimentary structure is imaged in malargue argentina secondly the method is used to reveal the structure of the midcontinent rift below the spree array in minnesota usa both studies demonstrate that structural information of the shallow crust 5 km below the arrays can be retrieved in particular the interpreted thickness of the sedimentary layer below the malargue array is in agreement with earlier studies in the same area being able to use global phases and direct p phases with large epicentral distances 80 to recover the earth s sedimentary structure suggests that glopsi can be applied in an industrial context

deep seated landslides affecting monoclinal flysch morphostructure evaluation of lidar derived topography of the highest range of the czech carpathians abstract the recent launch of national scale lidar derived topographic data provides an opportunity for re evaluating the geomorphic imprint of landslides in forested mountains a lidar based inventory of deep seated landslides dsls in the highest part of czech outer western carpathians moravskoslezske beskydy mts reveals that nearly 20 of the territory is affected by ancient dsls rather than the topography itself we show that the geological characteristics of flysch rocks control the density scaling relationships and morphometry of dsls they reveal a strong tendency to clustering in areas with favourable structural conditions such as cataclinal slopes of individual monoclinal ridges formed by thick bedded sandstones in comparison with high mountain areas and regions dominated by weaker lithology e g claystone dominated flysch sandstone dominated monoclinal structure of the moravskoslezske beskydy mts features predominantly short travelled dsls that are arrested on slopes and thus reveal a higher slope gradient than non landslide terrain finally we propose a conceptual model for the evolution of dsls on monoclinal flysch morphostructures particularly where coherent sandstone caps overlie weak claystone siltstone dominated flysch in these conditions we distinguish between low and high monoclinal ridges where the former is capped by relatively thin sandstones overlying claystone formations and sandstones predominate in the structure of the latter we show that the density of dsls on the cataclinal dip slopes is similar on both types of monoclinal ridges but that major differences exist in the evolution of anaclinal escarpment slopes here low monoclinal ridges are highly affected by dsls but escarpments of high monoclinal ridges are nearly devoid of any dsls

extent and timing of the last glacial maximum lgm in britain and ireland a review the last glacial maximum lgm of marine isotope stage mis 2 is defined here as the period either of maximum global ice volume or in which major ice sheets reached their maximum extent both definitions lack clarity as there is no reason to suppose that maximum volumes or limits were reached simultaneously at either all ice sheets or around the margins of individual ice sheets here we review the traditional terrestrial limits of the biis british irish ice sheet examine developments in understanding the offshore record and attempt a redefinition of the extent and timing of the mis 2 maximum as a working chronological model the build up of the biis is assigned to after 35 32 ka the maximum to the period 27 21 ka and a more limited readvance after 19 ka as marginal oscillations driven by ice sheet dynamics appear to have characterised much of the advance and especially the retreat of the biis caution should be exercised in assigning climatic significance to the many identified ice limits or still stands while much of the terrestrial limit in britain remains relatively unaltered significant revision is required offshore around britain and ireland to portray an extensive ice advance to the shelf edge and a period when the biis was conjoined with the adjacent fenno scandinavian ice sheet although there appears to be a broad synchrony between the biis and other major ice sheets local controls have produced some variation in the timing of advance to and retreat from maximum limits for particular ice streams or lobes but much of the offshore limit remains very poorly age constrained consequently a key objective in future research should be to improve and refine the chronological control for all portions of the maximum margin of the biis and its subsequent retreat stages copyright 2010 john wiley sons ltd

surface wave array tomography in se tibet from ambient seismic noise and two station analysis i phase velocity maps summary empirical green s functions egfs between pairs of seismographs can be estimated from the time derivative of the long time cross correlation of ambient seismic noise these egfs reveal velocity dispersion at relatively short periods which can be used to resolve structures in the crust and uppermost mantle better than with traditional surface wave tomography we combine rayleigh wave dispersion estimates from egfs and from traditional two station ts analysis into a new approach to surface wave array tomography with data from dense receiver arrays we illustrate the methodology with continuous broad band recordings from a temporary seismographic network on the southeastern part of the tibetan plateau in sichuan and yunnan provinces sw china the egfs are robust under temporal changes in regional seismicity and the use of either ambient noise approximated by records without signal from events with magnitude mb 5 or 4 or surface wave coda produces similar results the egfs do not strongly depend on the presence of large earthquakes but they are not reciprocal for stations aligned in the n s direction this directionality reflects the paucity of seismicity to the north of the array using a far field representation of the surface wave green s function and an image transformation technique we infer from the egfs the rayleigh wave phase velocity dispersion in the period band from 10 30 s a classical ts approach is used to determine rayleigh wave phase velocity dispersion between 20 120 s together they constrain phase velocity variations for t 10 120 s which can be used to study the structure from the crust to the upper mantle beneath se tibet short and intermediate period 10 80 s phase velocities are prominently low suggesting that the crust and upper mantle beneath se tibet is characterized by slow shear wave propagation

application of the linear dispersion relation with respect to depth inversion and remotely sensed imagery remote sensing methods have been developed to estimate bathymetry through the use of a theoretical relationship between wave speed and water depth known as the linear finite depth dispersion equation for surface gravity waves the authors describe a validation effort encompassing several hundred observations of wavenumber magnitude for sea swell frequencies obtained over a wide variety of conditions to investigate possible error sources resulting from the practical application of this relationship these wavenumber estimates were computed from pressure gauge signals using signal processing algorithms that can be equivalently applied to measurements of wave phase as imaged through remote sensors the major goal was to determine the accuracy of the dispersion relation while attempting to minimize errors associated with sensor positioning tidal variations and doppler shifts due to mean currents for water depths outside the surf zone the linear dispersion relation is highly accurate with average depth estimation errors on the order of 3 9 of the observed depth in shallower regions nominally less than 4 m for this field site where wave breaking is evident and nonlinear shoaling effects are more pronounced normalized depth errors of over 50 were commonly observed with most predictions being deeper than observations strong correlation between these bias errors and measured wave heights emphasizes the importance of accounting for wave amplitude in the calculation of shallow water phase speeds for depth estimation a simple depth correction is provided to allow for bathymetry estimation within the surf zone

rip current types circulation and hazard abstract rip currents are narrow and concentrated seaward directed flows that extend from close to the shoreline through the surf zone and varying distances beyond rip currents are ubiquitous on wave exposed coasts each year they cause hundreds of drowning deaths and tens of thousands of rescues on beaches worldwide and are therefore the leading deadly hazard to recreational beach users the broad definition above masks considerable natural variability in terms of rip current occurrence in time and space flow characteristics and behaviour in particular surf zone rip currents have long been perceived as narrow flows extending well beyond the breakers flushing out the surf zone at a high rate exit flow circulation regime while more recent studies have shown that rip flow patterns can consist of quasi steady semi enclosed vortices retaining most of the floating material within the surf zone circulatory flow circulation regime building upon a growing body of rip current literature involving numerical modelling and theory together with emergence of dense lagrangian field measurements we develop a robust rip current type classification that provides a relevant framework to understand the primary morphological and hydrodynamic parameters controlling surf zone rip current occurrence and dynamics three broad categories of rip current types are described based on the dominant controlling forcing mechanism each category is further divided into two types owing to different physical driving mechanisms for a total of six fundamentally different rip current types hydrodynamically controlled 1 shear instability rips and 2 flash rips which are transient in both time and space and occur on alongshore uniform beaches bathymetrically controlled 3 channel rips and 4 focused rips which occur at relatively fixed locations and are driven by hydrodynamic processes forced by natural alongshore variability of the morphology in both the surf zone and inner shelf zone and boundary controlled 5 deflection rips and 6 shadow rips which flow against rigid lateral boundaries such as natural headlands or anthropogenic structures for each rip current type flow response to changes in hydrodynamic and morphologic forcing magnitude is examined in regard to velocity modulation and changes in circulation regime providing key force response relationships of rip currents we also demonstrate that in the real world rip currents form through a mixture of driving mechanisms and the discrete rip types defined in fact form key elements in a wide and complex spectrum of rip currents on natural beaches it is anticipated that this rip current type classification will serve as a resource for coastal scientists and non specialists with an interest in the rip current hazard and as a platform for future rip current studies finally we suggest some important future research directions highlighting the need for coastal and beach safety communities to collaborate in order to improve rip current education and awareness

a combined geomorphological and geophysical approach to characterising relict landslide hazard on the jurassic escarpments of great britain abstract the jurassic escarpment in the north york moors in northern britain has a high density of deep seated relict landslides but their regional hazard is poorly understood due to a lack of detailed case studies investigation of a typical relict landslide at great fryup dale suggests that the crop of the whitby mudstone formation is highly susceptible to landslide hazards the mudstone lithologies along the escarpment form large multiple rotational failures which break down at an accelerated rate during wetter climates and degrade into extensive frontal mudflows geomorphological mapping high resolution lidar imagery boreholes and geophysical ert surveys are deployed in a combined approach to delimit internal architecture of the landslide cross sections developed from these data indicate that the main movement displaced a bedrock volume of c 1 107 m3 with a maximum depth of rupture of c 50 m the mode of failure is strongly controlled by lithology bedding joint pattern and rate of lateral unloading dating of buried peats using the ams method suggests that the 10 m thick frontal mudflow complex was last active in the late holocene after c 2270 30 calendar years bp geomorphic mapping and dating work indicates that the landslide is dormant but slope stability modelling suggests that the slope is less stable than previously assumed implying that this and other similar landslides in britain may become more susceptible to reactivation or extension during future wetter climatic phases this study shows the value of a multi technique approach for landslide hazard assessment and to enhance national landslide inventories

quantification of sand bar morphology a video technique based on wave dissipation a technique is presented to remotely measure the scales and morphology of natural sand bars based on the preferential dissipation of wind waves and swell over the crests of the bar photographic or video images are recorded and statistical uncertainties associated with incident wave height modulations removed by averaging time exposures ground truth testing of the technique was carried out as part of the superduck experiment in october 1986 the time exposures generally provided a good mapping of underlying morphology allowing detection of the bar and determination of cross shore and longshore length scales however during high waves persistent surface foam obscures the relationship of image intensity to local dissipation modeled theoretically by dissipation of a random wave field and an enhancement technique of image differencing must be done to remove the bias errors in the estimate of bar crest distance from the shoreline are generally less than 35 but this value depends on the geometry of the particular bar logistic simplicity and quantitative capabilities make this technique very attractive

deep seated gravitational slope deformations in the highest parts of the czech flysch carpathians evolutionary model based on kinematic analysis electrical imaging and trenching deep seated gravitational slope deformations dsgsds played an important role during the quaternary evolution of mountain ridges formed by anisotropic flysch rocks of the outer western carpathians owc four dsgsd affected ridges in the highest part of the czech sector of the owc have been subjected to multidisciplinary investigation involving mapping structural and kinematic analysis geoelectrical imaging trenching and dating all the studied dsgsds are strongly predisposed by regional structural fabric given by the intersection of bedding planes joint sets and faults performed research suggests high diversity of mechanisms leading to the origin of individual dsgsds the area of a single dsgsd can be affected by various types of movements such as sackung lateral spreading toppling or incipient sliding electrical imaging and trenching revealed that besides these mechanisms anisotropic flysch massifs formed by thick bedded sandstones are strongly exposed to subsurface opening of air filled voids related to widened crevices such a process is driven by deep seated creep and translational sliding of sandstone beds upon plastic claystones whose strength has been reduced to residual values of the angle of internal friction performed radiocarbon and osl dating revealed that some of the studied dsgsds originated in the holocene period particularly in the atlantic and subboreal chronozones

ocean surface features and currents measured with synthetic aperture radar interferometry and hf radar this paper describes the results of the first quantitative comparison between high resolution ocean surface current fields extracted from interferometric synthetic aperture radar insar measurements and those from a high frequency hf ocean surface current radar oscr system data from each of these radar systems along with supporting measurements from shipboard and buoy mounted sensors were collected during the high resolution remote sensing experiment high res on june 20 1993 on the continental shelf off the coast of cape hatteras north carolina both components of the surface current were obtained from the insar system at roughly 10 m resolution from two orthogonal flight legs over the region separated in time by about 30 min the oscr system measured two dimensional surface current vectors at about 1 km resolution over this same region while the usns bartlett was collecting hydrographic samples and near surface current measurements two dimensional wave spectra as well as meteorological and additional current measurements were collected at two buoys within the experimental area we discuss in the paper two techniques for eliminating the effect of surface wave motion on the insar current estimates one method relies on some knowledge of the local wind and wave field and the use of a microwave scattering model the other method makes use of a few in situ current measurements spaced at different range locations across the insar image using either of these techniques we find that the agreement between the insar and oscr current estimates is generally very good furthermore the insar current and magnitude imagery show the presence of undulating surface features where abrupt changes in the current speed and direction occurred the ship surveys indicate that these features were caused by the collision of water masses of different density we show for the first time in this paper a high resolution area extensive vector surface current map derived from the insar of the two dimensional flow in the vicinity of these features our results demonstrate convincingly that high resolution oceanic surface current vectors can be derived from insar current measurements and that these measurements may be very beneficial for detailed studies of the dynamics of small scale surface features in regions of strong current divergences or shears

the landslide response of alpine basins to post little ice age glacial thinning and retreat in southwestern british columbia abstract the role of post little ice age lia neoglacial retreat on landslide activity is investigated in 19 alpine basins along the upper lillooet river valley british columbia we examine how neoglacial scouring and glacial recession have modified hillslope form and slope stability and construct a decision making flowchart to identify landslide hazards associated with glacial retreat this work is based on field mapping gis analysis statistical associations between landslides and terrain attributes and a comparison between neoglaciated and non neoglaciated terrain within each basin the bedrock landslide response to glacial retreat varies appreciably according to lithology and the extent of glacial scour below the lia trimline valleys carved in weak quaternary volcanics show significant erosional oversteepening and contain deep seated slope movement features active rock fall rock slides and rock avalanches near glacial trimlines basins in stronger granitic rock rarely show increased bedrock instability resulting from post lia retreat except for shallow seated rock slides along some trimlines and failures on previously unstable slopes in surficial materials landslides associated with post lia retreat originate in till or colluvium as debris slides or debris avalanches and are concentrated along lateral moraines or glacial trimlines significant spatial association was also observed between recent catastrophic failures gravitational slope deformation and slopes that were oversteepened then debuttressed by glacial erosion eight out of nine catastrophic rock slope failures occurred just above glacial trimlines and all occurred in areas with a previous history of deep seated gravitational slope movement implying that this type of deformation is a precursor to catastrophic detachment

estimates of currents in the nearshore ocean region using interferometric synthetic aperture radar microwave remote sensing of the ocean surface using synthetic aperture radar sar is of great interest due to its high resolution and the potential of nearly instantaneous coverage of large areas the experience accumulated in ocean imaging by sar indicates that there are substantial difficulties in interpretation of the obtained images of ocean wave systems ocean surface currents are almost impossible to obtain from sar imagery the present paper reports on measurements of ocean surface currents based on imaging of the nearshore regions of the monterey bay using an interferometric sar the method is a modification of the conventional sar which employs two spatially separated antennas this modification allows one to construct an interferogram from the two complex images obtained by each antenna which provides direct mapping of the observed surface velocities the present results demonstrate the advantages of this novel technique in studying nearshore ocean surface dynamics in particular spatial distribution of the longshore current velocity is presented

quantifying riverine surface currents from time sequences of thermal infrared imagery 1 river surface currents are quantified from thermal and visible band imagery using two methods one method utilizes time stacks of pixel intensity to estimate the streamwise velocity at multiple locations the other method uses particle image velocimetry to solve for optimal two dimensional pixel displacements between successive frames field validation was carried out on the wolf river a small coastal plain river near landon mississippi united states on 26 27 may 2010 by collecting imagery in association with in situ velocities sampled using electromagnetic current meters deployed 0 1 m below the river surface comparisons are made between mean in situ velocities and image derived velocities from 23 thermal and 6 visible band image sequences 5 min length during daylight and darkness conditions the thermal signal was a small apparent temperature contrast induced by turbulent mixing of a thin layer of cooler water near the river surface with underlying warmer water the visible band signal was foam on the water surface for thermal imagery streamwise velocities derived from the pixel time stack and particle image velocimetry technique were generally highly correlated to mean streamwise current meter velocities during darkness r2 typically greater than 0 9 and early morning daylight r2 typically greater than 0 83 streamwise velocities from the pixel time stack technique had high correlation for visible band imagery during early morning daylight hours with respect to mean current meter velocities r2 0 86 streamwise velocities for the particle image velocimetry technique for visible band imagery had weaker correlations with only three out of six correlations performed having an r2 exceeding 0 6

seismic attenuation from recordings of ambient noise abstractwe applied seismic interferometry to data from an ocean bottom survey offshore norway and found that ambient seismic noise can be used to constrain subsurface attenuation on a reservoir scale by crosscorrelating only a few days of recordings by broadband ocean bottom seismometers we were able to retrieve empirical green s functions associated with surface waves in the frequency range between 0 2 and 0 6 hz and acoustic waves traveling through the sea water between 1 0 and 2 5 hz we discovered that the decay of these surface waves cannot be explained by geometrical spreading alone and required an additional loss of energy with distance we quantified this observed attenuation in the frequency domain using a modified bessel function to describe the cross spectrum in a stationary field we averaged cross spectra of equally spaced station couples and sorted these azimuthally averaged cross spectra with distance we then obtained frequency dependent estimates of attenuation by minimizing the misfit

paraglacial gravitational deformations in the sw alps a review of field investigations 10be cosmogenic dating and physical modelling catastrophic deep seated landslides dsl are generally considered to be the result of large slope deformations also known as deep seated gravitational slope deformation dsgsd this paper aims to build a synthesis of multiple studies made in the tinee valley southern french alps to assess the geometrical kinematical mechanical and chronological relationships between these two gravitational processes at the scale of the valley data issued from geological geomorphological and 10be dating indicate a clear geometrical link between dsgsd and dsl occurring at the base of the slope and suggest that gravitational slope evolution began after the glacial retreat 13 ka bp this is supported by the example of the well documented la clapiere slope a continuous evolution process is characterized geometrically and temporally from geomorphic observations and analogue modelling coupling structural geomorphological physical and chronological studies allowed us to propose a four dimensional 4d deformation model mechanically correlated with progressive failure concept the validity and variability of this reference site are discussed at the valley scale taking isola and le pra slope deformation as examples it allows a rough estimation of the state of slope deformation at the valley scale to be constructed and the slope evolution with time to be considered this 4d model could then be considered as a reference for other deep seated gravitational slope deformations in comparable alpine valleys

retrieving surface waves from ambient seismic noise using seismic interferometry by multidimensional deconvolution retrieving virtual source surface waves from ambient seismic noise by cross correlation assumes among others that the noise field is equipartitioned and the medium is lossless violation of these assumptions reduces the accuracy of the retrieved waves a point spread function computed from the same ambient noise quantifies the associated virtual source s spatial and temporal smearing multidimensional deconvolution mdd of the retrieved surface waves by this function has been shown to improve the virtual source s focusing and the accuracy of the retrieved waves using synthetic data we tested mdd on data recorded during the batholiths experiment a passive deployment of broadband seismic sensors in british columbia canada the array consisted of two approximately linear station lines using 4 months of recordings we retrieved fundamental mode rayleigh waves 0 05 0 27 hz we only used noise time windows dominated by waves that traverse the northern line before reaching the southern 2 5 of all data compared to the conventional cross correlation result based on this subset the mdd waveforms are better localized and have significantly higher signal to noise ratio furthermore mdd corrects the phase and the spatial deconvolution fills in a spectral f k domain gap between the single frequency and double frequency microseism bands frequency whitening of the noise also fills the gap in the cross correlation result but the signal to noise ratio of the mdd result remains higher comparison of the extracted phase velocities shows some differences between the methods also when all data are included in the conventional cross correlation

waves at holderness from x band radar abstract during the holderness experiment of 1994 1995 and 1995 1996 data were collected by a coastal deployment of an x band radar with simultaneous deployments of various moored and bottom mounted wave measurement devices the radar data consist of sequences of images of the sea surface at intervals of 1 5 h over several months three dimensional wave number frequency spectra were derived from the sequences of captured images using an analysis method developed by young et al j geophys res 90 c1 1985 1049 some aspects of this analysis were refined an empirical transfer function was derived relating the radar image spectra to the wave spectra measured by other instruments a new calibration procedure for obtaining wave height from the radar spectra was also derived the radar spectra were compared with directional spectra collected by a bottom mounted interocean s4dw directional wave current meter and with datawell waverider data the capabilities of x band radar in a coastal situation are discussed including the derivation of water depth required to optimise the analysis

wave transformation across the inner surf zone sea and swell wave heights observed on transects crossing the mid and inner surf zone on three beaches a steep concave up beach a gently sloped approximately planar beach and a beach with an approximately flat terrace adjacent to a steep foreshore were depth limited i e approximately independent of the offshore wave height consistent with previous observations the wave evolution is well predicted by a numerical model based on the one dimensional nonlinear shallow water equations with bore dissipation the model is initialized with the time series of sea surface elevation and cross shore current observed at the most offshore sensors located about 50 to 120 m from the mean shoreline in mean water depths 0 80 to 2 10 m the model accurately predicts the cross shore variation of energy at both infragravity nominally 0 004 f 0 05 hz and sea swell here 0 05 f 0 18 hz frequencies in models of surf zone hydrodynamics wave energy dissipation is frequently parameterized in terms of s the ratio of the sea swell significant wave height to the local mean water depth the observed and predicted values of s increase with increasing beach slope and decreasing normalized by a characteristic wavenumber k water depth kh and are well correlated with kh a measure of the fractional change in water depth over a wavelength errors in the predicted individual values of s are typically less than 20 it has been suggested that infragravity motions affect waves in the sea swell band and hence s but this speculation is difficult to test with field observations numerical simulations suggest that for the range of conditions considered here s is insensitive to infragravity energy levels

rock slope deformation at affliction creek southern coast mountains british columbia a 7 year record of rock slope deformation is reported from affliction creek in the southern coast mountains of british columbia an estimated 3 107 m3 of monzonite basement and overlying garibaldi aged volcanic material is involved in a slow gravitational movement ground motion vectors suggest that movement has occurred along a deep seated shear zone and was accompanied by a downslope extension of the moving mass near surface flexural toppling producing antislope scarps has taken place where tension cracks crop out on steep slopes or wherever rock faces with strong planar jointing are glacially undercut structural data indicate the feasibility of both sliding and toppling at this site the stratigraphic evidence indicates that most of the tension cracks grabens and antislope scarps constituting the slope movement complex are less than 4300 years old and that many of these landforms may have developed quite recently as a result of rock slope debuttressing during the retreat of affliction glacier

s band doppler radar measurements of bathymetry wave energy fluxes and dissipation across an offshore bar the use of a shore based microwave doppler radar for the remote sensing of ocean wave propagation over an offshore sand bar was investigated the radar yielded high spatial resolution measurements of several quantities of importance in the study of bar dynamics the spatial variation in wave phase with distance along the radar beam direction was used to calculate bathymetry with sufficient accuracy and resolution to clearly reveal the presence of the bar and the tidal cycle variation of water depth this real time bathymetry enabled the calculation of ocean wave energy fluxes from the radar velocity data these energy fluxes showed good agreement with predictions from a numerical wave propagation model except in regions of significant wave breaking where the discrepancy between measured and modeled fluxes was found to be closely related to the modeled wave dissipation rate

seismic noise correlations to image structural and mechanical changes associated with the mw 7 9 2008 wenchuan earthquake we locate temporal changes of seismic wave speed and scattering properties of the crust associated with the 2008 mw7 9 wenchuan earthquake to that end we analyze ambient seismic noise records from 2007 until the end of 2008 in the 1 3 s period band and in the 12 20 s period band measured in a region that covers the southern two thirds of the fault activated during the earthquake to locate the changes we use a refined imaging procedure based on the sensitivity of scattered waves to weak perturbations this inverse method uses the radiative transfer approximation to describe the intensity of the noise correlation coda our results show that the largest structural changes are observed northeast of the wenchuan epicenter around the fault zone where aftershocks are distributed the spatial and temporal characteristics of the behavior of the crust at depth around the wenchuan earthquake suggest a postseismic and geology dependent signature of the middle crust we also observe a clear seasonal signature within the sichuan basin at depth that we relate to the heavy rainfalls during the monsoon season this seasonality can also be observed at the surface in form of a waveform decoherence our study highlights that seismic velocity changes and waveform decoherence are independent measurements that are sensitive to different parameters and can thus give complementary information in our study we also point out the value of studying the evolution of the changes at different times in the coda

reconstruction of landslide movements using digital elevation model and electrical resistivity tomography analysis in the polish outer carpathians abstract landslides are a major threat to the environment infrastructure and human activities especially in mountainous and hilly areas it is therefore important to accurately identify the mass movements triggering these mechanisms this paper presents the impacts of lithotectonic conditions on the formation of mass movements on the example of the landslide that is located in the northern part of the polish outer carpathians in the area of the research the ratio of the total area of landslides to the surface of the area reaches even 20 the interpretation of a high resolution digital elevation model dem electrical resistivity tomography ert and fieldwork results allowed for the reconstruction of the landslide movements and dividing them into two areas the western one dominated by rotational movement and the eastern one featuring rotational and translational movement it was found that the eastern part is more active now as it probably was also in the past which might have resulted from the lithotectonic conditioned or from the impact of the flowing waters of the dunajec river moreover in the eastern part of the landslides a small sized ridge 55 m 25 m was identified which shows greater stability in comparison with the colluvium that surrounds it in order to explain the lower rate of movement of this landform a morphometric analysis and research using ert were performed the geophysical measurements showed that the ridge comprised rock formations of greater resistivity than its surroundings it is most likely that the only preserved sandstone packet constituting the original secondary escarpment became separated from the bedrock due to rotational movement the presented studies indicate that the landslide was created due to geological and atmospheric conditions a clear revival of landslide movements took place after significant precipitation events that last occurred in the years 2010 and 2015 the bedrock substrate due to its lithology and tectonics facilitates these movements it was found that the landslide studied is a complex entity characteristic of the polish outer carpathians that has undergone multiple stages of development the landslide is active or periodically active and therefore must be excluded from the planned development as well as from other forms of human activity

valley shape influence on deformation mechanisms of rock slopes stress distribution in mountainous areas is influenced by local morphology valley morphology and the relationship between main and tributary valleys strongly depend on geological characteristics and evolution they may control the evolution of slope instabilities especially when interacting with pervasive structural features we performed parametric three dimensional 3d numerical modelling of simplified slope geometries with variable slope angle from 218 to 358 length combining different orientations for different slope sectors and changing attitude of pervasive planes of anisotropy foliation schistosity bedding data used in the 3d models are the initial slope geometry rock mass properties and internal anisotropy we assumed mohr coulomb behaviour with the presence of ubiquitous joints and different piezometric levels the model results show that plastic deformation initiates near the highest ridge just after deglaciation commences a shear zone develops and propagates toward the toe of the slope and its shape is strongly controlled by slope geometry anisotropy and in situ stresses the thickness of the failing mass for model slope reliefs up to 3200 m increases from 50 mto some hundreds of metres during glacier retreat and it depends on geometry of slopes anisotropy and in situ stresses results are compared to examples of deep seated slope deformations from the alps which helps in the interpretation of such phenomena and in the understanding of their influence on valley evolution

quantification of swash flows using video based particle image velocimetry understanding of fluid flows and sediment transport in the foreshore has been severely hampered by the difficulty of obtaining swash flow velocity measurements in this dynamic and extremely shallow region we present a digital imaging method known as particle image velocimetry piv to quantify the horizontal flow structure of swash this technique exploits similar patterns of image intensity in multiple images sampled sequentially to identify spatial offsets corresponding with maximum correlations between image subregions these offsets are used in conjunction with the sampling interval to derive velocity vectors describing the horizontal flow structure pre processing methods to geo rectify oblique imagery to a planar surface and post processing methods of correcting spurious vectors are described the piv method overcomes many of the limitations of in situ sampling of swash flows and is shown consistent with results from a previously tested remote sensing technique for measuring swash edge velocities in general this technique provides a unique capability for spatially extensive and well resolved quantification of swash flows

the spatial and temporal variability of sand bar morphology the spatial and temporal variability of nearshore sand bar morphology is quantified using a unique data set spanning 2 years the data consist of daily time exposure images of incident wave breaking on an open coast sandy beach which may be used to infer bar morphology lippmann and holman 1989 the morphology in each image is classified into an eight state morphologic scheme in which bars are uniquely defined by four independent criteria the most frequently observed morphologies are the longshore periodic rhythmic bars observed in 68 of the data linear bars occur under highest wave conditions h s 1 78 m and are unstable mean residence time 2 days shore attached rhythmic bars are the most stable mean residence time 11 days and generally form 5 16 days following peak wave events non rhythmic three dimensional bars are very transient mean residence time 3 days eighty seven percent of transitions to lower bar types defined in text occurred one state at a time supporting our selection of the ordering of states and suggesting the suitability of a sequential morphology model transitions to higher states occurred under rising wave energy and were evenly spread among the possible higher states with more substantial changes in morphology resulting from larger wave increases this suggests that up state erosional transitions based on offshore bar migration are better described by an equilibrium model where response is better correlated with incident wave energy than with preceding morphological state time exposure images were also digitized to yield quantitative estimates of bar crest location as a function of longshore distance principal component analysis was used to decompose bar position into two dimensional linear and three dimensional longshore variable components cross shore linear bar position ranges 50 m about the 2 year mean 27 m standard deviation and dominates bar variability 74 6 three dimensional bar structure accounts for 14 of the variance 12 m standard deviation changes in incident wave height precede cross shore bar migration by less than 1 day changes in longshore variability are inversely correlated to changing wave conditions with bar morphology becoming linear rapidly during storms on time scales of less than 1 day evolution to significantly three dimensional structure typically occurs over 5 7 days following peak wave events

quantified time scale for glacial valley cross profile evolution in alpine mountains space is used as a proxy for time in determining the role of glaciation in shaping valley cross profiles in the two thumb range southern alps new zealand the range is undergoing rapid tectonic transport and uplift as it is advected toward the alpine fault repeated cycles of glacial erosion during the quaternary have fashioned u shaped valleys in the north of the range close to the main divide while valleys in the less glaciated south of the range have rounded divides and convex fluvial cross profiles tectonic transport and uplift rates coupled with an offshore oxygen isotope 18o record and glacial geological reconstructions allow time constraints to be applied to valley development along the range valley width and depth measurements and power law equations were used to quantify the shape of cross profile transects in 37 valleys valleys evolved into a characteristic u shaped cross profile formed over 400 k y of glacial occupancy this regardless of other models of glacial flattening of valley long profiles suggests that alpine glaciation excavates greater volumes of rock indicating that glaciers are a more effective erosional agent than fluvial activity in alpine mountain belts

cosmogenic 10be dating of a sackung and its faulted rock glaciers in the alps of savoy france sackungs are the largest gravitational deformation observed in mountains they are characterized by the long term slowness of the movements but their mechanism is still not well understood nowadays cosmic ray exposure cre dating methods allow dating the morphologic structures involved in sackung and can contribute at the understanding of their origin in the alps the 5 3 km long arcs sackung initiated during the activity of rock glaciers three samples from these faulted rock glaciers provide their first cre ages and show that at 2000 m elevation these block accumulations moved during the younger dryas and stopped in early holocene six 10be ages of fault scarps show that the arcs sackung lasted only a few thousand years and stopped at about 8462 432 10be yr they also reveal that deformation migrated upslope in agreement with a mechanism of flexural toppling of vertical layers this unique and long gravitational event characterized by migration of the deformation does not support earthquake shaking as triggering mechanism for individual faults it shows that in the upper isere valley slope deformation was delayed of several thousand years after glacial debuttressing and is not anymore active despite its fresh morphology

radar derived interferometric surface currents and their relationship to subsurface current structure radar derived ocean surface currents are analyzed in conjunction with in situ acoustic doppler current profiler adcp measurements the interferometric measurements were collected by an x band imaging doppler radar in a manner analogous to those of along track interferometric synthetic aperture radar ati sar while the advent of ati sar has provided a new potentially powerful technique for current mapping the relationship between surface currents and interferometric velocity measurements is not yet clearly understood this paper presents comparisons between radar derived and in situ current measurements to develop a precise method for estimating the surface current from interferometric measurements the influence of long wave orbital velocities and the influence of bragg resonant waves are studied we find that coupling between the orbital velocity and backscattered power i e the modulation transfer function can bias surface current estimates potentially by up to 20 cm s 1 in an upwind viewing orientation furthermore experimental observations verify a cos 2n 0 2 analytical model for the directional spreading of bragg resonant waves extending our analysis to include subsurface currents case studies are presented under varying environmental conditions for which the vertical current structure changes considerably analysis of radar imagery yields both radial surface currents and vector subsurface current estimates derived from long wave dispersion characteristics combining these with coincident adcp measurements yields a vertical profile of current using these measurement techniques we make several observations within the upper meter of the ocean these profiles reveal the sensitivity of x band interferometric measurements to wind drift and the near surface current structure

green lake landslide and other giant and very large postglacial landslides in fiordland new zealand abstract green lake landslide is an ancient giant rock slide in gneiss and granodiorite located in the deeply glaciated fiordland region of new zealand the landslide covers an area of 45 km 2 and has a volume of about 27 km 3 it is believed to be new zealand s largest landslide and possibly the largest landslide of its type on earth it is one of 39 known very large 10 6 10 7 m 3 and giant 10 8 m 3 postglacial landslides in fiordland discussed in the paper green lake landslide resulted in the collapse of a 9 km segment of the southern hunter mountains slide debris moved up to 2 5 km laterally and 700 m vertically and formed a landslide dam about 800 m high impounding a lake about 11 km long that was eventually infilled with sediments geomorphic evidence supported by radiocarbon dating indicates that green lake landslide probably occurred 12 000 13 000 years ago near the end of the last otira glaciation the landslide is described and its geomorphic significance age failure mechanism cause and relevance in the region are discussed in relation to other large landslides and recent earthquake induced landslides in fiordland the slope failure occurred on a low angle fault zone undercut by glacial erosion and was probably triggered by strong shaking mm ix x associated with a large m 7 5 8 earthquake on the alpine fault c 80 km to the northwest geology was a major factor that controlled the style and size of green lake landslide and in that respect it is significantly different from most other gigantic landslides future large earthquakes on the alpine fault in fiordland are likely to trigger more very large and giant landslides across the region causing ground damage and devastation on a scale that has not occurred during the last 160 years with potentially disastrous effects on towns tourist centres roads and infrastructure the probability of such an event occurring within the next 50 years may be as high as 45

observations of swash zone velocities a note on friction coefficients 1 vertical flow structure and turbulent dissipation in the swash zone are estimated using cross shore fluid velocities observed on a low sloped fine grained sandy beach raubenheimer 2002 with two stacks of three current meters located about 2 5 and 8 cm above the bed the observations are consistent with an approximately logarithmic vertical decay of wave orbital velocities within 5 cm of the bed the associated friction coefficients are similar in both the uprush and downrush as in previous laboratory results turbulent dissipation rates estimated from velocity spectra increase with decreasing water depth from o 400 cm2 s3 in the inner surf zone to o 1000 cm2 s3 in the swash zone friction coefficients in the swash interior estimated with the logarithmic model and independently estimated by assuming that turbulent dissipation is balanced by production from vertical shear of the local mean flow and from wave breaking are between 0 02 and 0 06 these values are similar to the range of friction coefficients 0 02 0 05 recently estimated on impermeable rough nonerodible laboratory beaches and to the range of friction coefficients 0 01 0 03 previously estimated from field observations of the motion of the shoreward edge of the swash run up

anelastic earth structure from the coherency of the ambient seismic field 1 cross correlation of the ambient seismic field is now routinely used to measure seismic wave travel times however relatively little attention has been paid to other information that could be extracted from these signals in this paper we demonstrate the relationship between the spatial coherency of the ambient field and the elastodynamic green s function in both time and frequency domains through measurement of the frequency domain coherency as a function of distance we sequentially recover phase velocities and attenuation coefficients from these measurements we generate 1 d shear wave velocity and attenuation models for southern california the ambient field measurements of attenuation and the exceptional path coverage that results from the many possible interstation measurements allow us to extend q estimates over a range of frequencies that has previously been difficult to analyze using earthquake data measurements from paths that cross major sedimentary basins show both lower wave speeds and lower quality factors than other paths as expected our results indicate that there is a wealth of information available in the spatial coherency of the ambient seismic field

shallow s wave velocity structure from ambient seismic noise at planchon peteroa volcanic complex argentina chileshallow s wave velocity structure from ambient seismic noise at planchon peteroa

reflection images from ambient seismic noise one application of seismic interferometry is to retrieve the impulse response green s function from crosscorrelation of ambient seismic noise various researchers show results for retrieving the surface wave part of the green s function however reflection retrieval has proven more challenging we crosscorrelate ambient seismic noise recorded along eight parallel lines in the sirte basin east of ajdabeya libya to obtain shot gathers that contain reflections we take advantage of geophone groups to suppress part of the undesired surface wave noise and apply frequency wavenumber filtering before crosscorrelation to suppress surface waves further after comparing the retrieved results with data from an active seismic exploration survey along the same lines we use the retrieved reflection data to obtain a migrated reflection image of the subsurface

middle and late pleistocene glacial lakes of lowland britain and the southern north sea basin focusing on lowland britain and the southern north sea basin this article reviews the sedimentary and geomorphic evidence for the main glacial lakes inferred during the middle and late pleistocene and evaluates their impacts on drainage basin development glacial lakes are best known from glaciations during marine isotope stages mis 12 6 and 2 although glacial lakes have also been inferred during mis 10 and 4 some lakes for example bosworth low level humber and the lakes of the eastern fenland margin are reconstructed from unequivocal sedimentary evidence including rhythmites and subaqueous outwash whereas others lakes for example lapworth and fenland are inferred mostly from erosional features and remain to be substantiated the largest known glacial lake developed in the southern north sea basin between an ice sheet to the north and a chalk bedrock ridge in the strait of dover area first during the anglian elsterian glaciation of mis 12 and again during the late wolstonian late saalian drenthe glaciation of mis 6 the palaeohydological impacts of lake drainage are thought to include cutting of the strait of dover as a result of catastrophic drainage from the north sea lake during mis 12 incision of a number of gorges and river valleys in england and diversion or even reversal of major rivers such as the thames and the proto soar avon system recently varve chronologies have been correlated with the greenland ice core record although caution is needed to discriminate between varves and non annual rhythmites future work on pleistocene glacial lakes needs to test chronologies of lake development by luminescence dating of glaciolacustrine sediments deposited in non ice proximal locations 1 fine grained rainout deposits and 2 wave rippled sands deposited in shallow water and to model the impacts of glacial isostasy in order to reconstruct lake extents all of this work should be based on the rigorous application of sedimentology to interpret sedimentary facies and depositional environments

large sackung along major tectonic features in the central italian alps deep seated gravitational slope deformation sackung is common in alpine mountain belts it is controlled by lithological geomorphological and structural features we describe and discuss five examples of dsgsd along the insubric line periadriatic fault in the central italian alps the five examples are different in morphology size state of activity and distribution and are located along both primary and secondary valleys we demonstrate relations between structural and gravitational features and discuss the possibility that structural has both passive and active roles in sackung development analysis of ps sar data shows that the studied examples are not active today numerical modelling demonstrates the importance of lithological and structural constraints postglacial debuttressing groundwater fluctuations and weathering on sackung triggering and development

assessment of the reliability of 2d inversion of apparent resistivity data the reliability of inversion of apparent resistivity pseudosection data to determine accurately the true resistivity distribution over 2d structures has been investigated using a common inversion scheme based on a smoothness constrained non linear least squares optimization for the wenner array this involved calculation of synthetic apparent resistivity pseudosection data which were then inverted and the model estimated from the inversion was compared with the original 2d model the models examined include i horizontal layering ii a vertical fault iii a low resistivity fill within a high resistivity basement and iv an upfaulted basement block beneath a conductive overburden over vertical structures the resistivity models obtained from inversion are usually much sharper than the measured data however the inverted resistivities can be smaller than the lowest or greater than the highest true model resistivity the substantial reduction generally recorded in the data misfit during the least squares inversion of 2d apparent resistivity data is not always accompanied by any noticeable reduction in the model misfit conversely the model misfit may for all practical purposes remain invariant for successive iterations it can also increase with the iteration number especially where the resistivity contrast at the bedrock interface exceeds a factor of about 10 in such instances the optimum model estimated from inversion is attained at a very low iteration number the largest model misfit is encountered in the zone adjacent to a contact where there is a large change in the resistivity contrast it is concluded that smooth inversion can provide only an approximate guide to the true geometry and true formation resistivity

wave runup video motion detection using the radon transform abstract a new method of runup detection from video imagery is introduced and validated at an energetic dissipative beach the instantaneous waterline is detected from uprush and backwash by using the radon transform rt the method is compared to conventional color contrast method from rgb images and lidar measurements in our observations the rt shows better detection skill even for adverse conditions such as those present on flat dissipative swash zones where contrast is reduced because the rt is a proxy of deeper waterline 0 1 m it is less sensitive to lack of contrast due to sand saturation moreover since it is based on motion detection it is less sensitive to changes in lighting conditions overall the rt offers an attractive alternative for long term automated detection of the runup

2d electrical resistivity imaging of some complex landslides in lucanian apennine chain southern italy we use high resolution electrical resistivity imaging to delineate the geometry of complex landslides in the lucanian apennine chain of southern italy to identify the discontinuity between the landslide material and bedrock and to locate possible surfaces of reactivation the lucanian apennine chain is characterized by high hydrogeological hazard and shows a complete panorama of mass movements in this area all typologies of landslides markedly predisposed and tightly controlled by the geostructural characteristics are found rotational and translational slides rototranslational slides earth and mudflows as well as deep seated gravitational slope phenomena with a predominance of rototranslational slides evolving as earthflow slides three test sites characterized by complex geology and a high hydrogeologic hazard are studied the giarrossa and varco izzo earthflow slides are located to the west and east of the town of potenza whereas the latronico slide is located close to the town of latronico

towards monitoring the englacial fracture state using virtual reflector seismology in seismology coda wave interferometry cwi is an effective tool to monitor time lapse changes using later arriving multiply scattered coda waves typically cwi relies on an estimate of the medium s impulse response the latter is retrieved through simple time averaging of receiver receiver cross correlations of the ambient field that is seismic interferometry si in general the coda is induced by heterogeneities in the earth being comparatively homogeneous however ice bodies such as glaciers and ice sheets exhibit little scattering in addition the temporal stability of the time averaged cross correlations suffers from temporal variations in the distribution and amplitude of the passive seismic sources consequently application of cwi to ice bodies is currently limited nevertheless fracturing and changes in the englacial macroscopic water content alter the bulk elastic properties of ice bodies which can be monitored with cryoseismological measurements to overcome the current limited applicability of cwi to ice bodies we therefore introduce virtual reflector seismology vrs vrs relies on a so called multidimensional deconvolution mdd process of the time averaged crosscorrelations the technique results in the retrieval of a medium response that includes virtual reflections from a contour of receivers enclosing the region of interest i e the region to be monitored the virtual reflections can be interpreted as artificial coda replacing the lacking natural scattered coda hence this artificial coda might be exploited for the purpose of cwi from an implementation point of view vrs is similar to si by mdd which as its name suggests also relies on a multidimensional deconvolution process si by mdd however does not generate additional virtual reflections advantageously both techniques mitigate spurious coda changes associated with temporal variations in the distribution and amplitude of the passive seismic sources in this work we apply si by mdd and vrs to synthetic and active seismic surface wave data the active seismic data were acquired on glacier de la plaine morte switzerland we successfully retrieve virtual reflections through the application of vrs to this active seismic data in application to both synthetic and active seismic data we show the potential of vrs to monitor time lapse changes in addition we find that si by mdd allows for a more accurate determination of phase velocity

love and rayleigh phase velocity maps 5 40 s of the western and central usa from usarray data abstract continuous data recorded on more than 1600 usarray seismic stations operating in the western and central us between 2006 and 2012 are used to map phase velocities of love and rayleigh waves at short periods 5 40 s using a noise correlation technique vertical and transverse records for all station pairs separated by less than 600 km are cross correlated in 4 h long segments and the resulting spectra are stacked for the time period of station operation dispersion curves are determined from the locations of zeros in the real component of the correlation spectra using a method based on that of aki 1957 phase velocity maps expanded on a 0 25 by 0 25 pixel grid are estimated by inversion of the phase velocity measurements comparison with predicted phase velocity maps based on the crustal model crust2 0 combined with the mantle model nd08 shows good agreement at the longer periods strong slow anomalies 25 in the short period maps are geographically correlated with basins and regions of thick sedimentary cover the strength of these anomalies is not well predicted by existing crustal velocity models

estimation of wave phase speed and nearshore bathymetry from video imagery a new remote sensing technique based on video image processing has been developed for the estimation of nearshore bathymetry the shoreward propagation of waves is measured using pixel intensity time series collected at a cross shore array of locations using remotely operated video cameras the incident band is identified and the cross spectral matrix is calculated for this band the cross shore component of wavenumber is found as the gradient in phase of the first complex empirical orthogonal function of this matrix water depth is then inferred from linear wave theory s dispersion relationship full bathymetry maps may be measured by collecting data in a large array composed of both cross shore and longshore lines data are collected hourly throughout the day and a stable daily estimate of bathymetry is calculated from the median of the hourly estimates the technique was tested using 30 days of hourly data collected at the sandyduck experiment in duck north carolina in october 1997 errors calculated as the difference between estimated depth and ground truth data show a mean bias of 35 cm rms error 91 cm expressed as a fraction of the true water depth the mean percent error was 13 rms error 34 excluding the region of known wave nonlinearities over the bar crest the accuracy of the technique improved and the mean rms error was 20 cm 75 cm additionally under low amplitude swells wave height h 1 m the performance of the technique across the entire profile improved to 6 29 of the true water depth with a mean rms error of 12 cm 71 cm

large ice contact slope movements glacial buttressing deformation and erosion glaciers and slope movements may act simultaneously to erode and modify glaciated slopes undercutting by glaciers can destabilize slopes but the extent to which slope failure may progress prior to subsequent glacier withdrawal has not hitherto been considered the traditional view has been that the buttressing effect of ice prevents slope movement the problem with this view is that ice is one third the density of rock and flows under low applied stress consequently failed slopes may move into the glacier if they exert a stress in excess of the resistance provided by the glacier slope movement rate depends on ice rheology and other factors influencing driving and resisting stresses simple viscous equations are used to investigate these variables the equations predict that small 108 m3 rockslides to test these estimates field evidence is presented of slope movements in glaciated valleys of new zealand narrowing or squeezing of glaciers adjacent to unstable rock slopes is demonstrated and considered to be the result of slope movement for one site geomorphic mapping and slope movement monitoring data show that movement rates are of similar order of magnitude to those predicted by the viscous equations closer agreement could be achieved with the application of modelling techniques that can more realistically model the complex slope geometries and stability factors encountered or by obtaining additional empirical data to calibrate the models this research implies that while the concept of glacial debuttressing the reduction of slope support from withdrawal of glaciers is valid complete debuttressing is not a prerequisite for the movement of ice contact rock slopes these slope movements may contribute to the erosional processes of glaciers and the evolution of glaciated slopes in a previously unrecognized way copyright 2012 john wiley sons ltd

tectonic vs gravitational morphostructures in the central eastern alps italy constraints on the recent evolution of the mountain range abstract deep seated gravitational slope deformations dsgsds influence landscape development in tectonically active mountain ranges nevertheless the relationships among tectonics dsgsds and topography are poorly known in this paper the distribution of dsgsds and their relationships with tectonic structures and active processes surface processes and topography were investigated at different scales over 100 dsgsds were mapped in a 5000 km2 sector of the central eastern alps between the valtellina engadine and venosta valleys detailed lineament mapping was carried out by photo interpretation in a smaller area about 750 km2 including the upper valtellina and val venosta fault populations were also analysed in the field and their mechanisms unravelled allowing to identify different structural stages the youngest being consistent with the regional pattern of the ongoing crustal deformation finally four dsgsd examples have been investigated in detail by geological and 2d geomechanical modelling dsgsds affect more than 10 of the study area and mainly cluster in areas where anisotropic fractured rock mass and high local relief occur their onset and development is subjected to a strong passive control by mesoscopic and major tectonic features including regional nappe boundaries as well as nw se n s and ne sw trending recent brittle structures the kinematic consistency between these structures and the pattern of seismicity suggests that active tectonics may force dsgsds although field evidence and numerical models indicate slope debuttressing related to deglaciation as a primary triggering mechanism

the seismic noise wavefield is not diffuse passive seismology is burgeoning under the apparent theoretical support of diffuse acoustics however basic physical arguments suggest that this theory may not be applicable to seismic noise a procedure is developed to establish the applicability of the diffuse field paradigm to a wavefield based on testing the latter for azimuthal isotropy and spatial homogeneity this procedure is then applied to the seismic noise recorded at 65 sites covering a wide variety of environmental and subsoil conditions considering the instantaneous oscillation vector measured at single triaxial stations the hypothesis of azimuthal isotropy is rejected in all cases with high confidence which makes the spatial homogeneity test unnecessary and leads directly to conclude that the seismic noise wavefield is not diffuse however such a conclusion has no practical effect on passive imaging which is also possible in non diffuse wavefields

structural monitoring of a highway bridge using passive noise recordings from street traffic structural damage on bridges presents a hazard to public safety and can lead to fatalities this article contributes to the development of an alternative monitoring system for civil structures based on passive measurements of seismic elastic waves cross correlations of traffic noise recorded at geophone receiver pairs were found to be sufficiently stable for comparison and sensitive to velocity changes in the medium as such velocity variations could be caused by damage their detection would be valuable in structural health monitoring systems a method originally introduced for seismological applications and named passive image interferometry was used to quantify small velocity fluctuations in the medium and thereby observe structural changes evaluation of more than 2 months of continuous geophone recordings at a reinforced concrete bridge yielded velocity variations v v in the range of 1 5 to 2 1 the observed fluctuations correlate with associated temperature time series with a striking resem

patterns of movement in reactivated landslides abstract the primary aim of this research was to study the relationship between landslide motion and its causes with reference to large slow moving reactivated translational rock slides surface displacements of the 22 106 m3 utiku landslide in central north island new zealand were measured using continuous gps cgps for three years the nature of the movement of such slides has often been difficult to determine because of poor temporal and spatial monitoring resolutions after removal of tectonic plate motion the temporal pattern of the landslide s surface motion could be understood to arise from irregular episodes of faster up to 21 mm day and slower up to 26 mm yr post failure landslide displacement and seasonal cyclic displacements of about 20 mm yr 10 mm per half year in alternating directions intervals of faster motion gave rise to displacements of between 10 and 120 mm per event faster displacement was associated mostly with basal sliding mechanism 1 involving deformation within a thin clay seam as recorded by borehole inclinometer surveys slower surface displacement involved permanent internal deformation of the larger landslide mass consisting of plastic deformation within the landslide body and or slip along existing internal planes of weakness and slip on the slide base mechanism 2 it accounted for up to 26 mm yr of displacement at a mean angle of about 49 from the horizontal indicating that the slide mass was thinning as it moved down slope seasonal cyclic displacements were synchronous with changes in pore pressure suggesting that it is a shrink swell process mechanism 3 associated with wetting and recharge of groundwater during the wetter winter months leading to a downslope movement and soil shrinkage leading to upslope rebounds during the dryer summer months the brief periods of faster displacement were triggered by seasonal peaks in pore pressure linked to long periods 12 to 20 weeks of increased precipitation and lowered evapotranspiration faster displacement however was not arrested by lowering pore pressure or by any other monitored factor similarly periods of slower displacement did not correlate with pore pressure changes or with any other monitored factor this study has shown that the annual movement pattern of a reactivated landslide is a combination of these processes that generate a complex overall movement record the field measurements showed real variability arising from variations in rainfall and pore pressure which were overprinted with measurement noise that may mask some other processes

water depth and surface current retrievals from airborne optical measurements of surface gravity wave dispersion visible images of nearshore ocean waves obtained from an aircraft have been utilized to estimate the surface currents and water depth below the waves a digital framing camera was mounted in a motion stabilized turret and used to obtain temporal sequences of high quality optical images of shoaling ocean waves data on the position and attitude of the camera turret were used to map the image data to a rectilinear coordinate system at the level of the surface effectively separating the spatial and temporal modulations due to the waves the resulting three dimensional 3 d space time data sets were fourier transformed to obtain frequency wave number spectra of these modulations these spectra contain information on the propagation characteristics of the waves such as their wavelengths and frequencies and their directions and speeds of propagation the water depth and current vector have been estimated by choosing these parameters so that a best fit is obtained between the theoretical dispersion relation for linear gravity waves and these 3 d wave spectra image data sets were acquired during the shoaling waves experiment showex along the quasi linear coastline in the vicinity of the army corps of engineers field research facility frf near duck on the north carolina outer banks summary wave parameters and bathymetry and current retrievals are typically within 10 of contemporaneous in situ measurements though outliers occur

on the relation between seismic interferometry and the simultaneous source method summary in seismic interferometry the response to a virtual source is created from responses to sequential transient or simultaneous noise sources in the simultaneous source method overlapping responses to sources with small time delays are recorded seismic interferometry and the simultaneous source method are related in this paper we make this relation explicit by discussing deblending as a form of seismic interferometry by multidimensional deconvolution

sediment transport partitioning in the swash zone of a large scale laboratory beach abstract swash zone sheet flow and suspended sediment transport rates are estimated on a coarse sand beach constructed in a large scale laboratory wave flume three test cases under monochromatic waves with wave heights of 0 74 m and wave periods of 8 and 12 2 s were analyzed sediment flux in the sheet flow layer exceeds several hundred kg m 2 s 1 during both uprush and backwash suspended sediment flux is large during uprush and can exceed 200 kg m 2 s 1 instantaneous sediment flux magnitudes in the sheet layer are nearly always larger than those for suspended sediment flux however sediment transport rates those integrated over depth indicate that suspended load transport is dominant during uprush for all cases and during the early stages of backwash except in the case for the 12 2 s wave case when the foreshore was steeper results could not be obtained for an entire swash event and were particularly truncated during backwash when water depths fell below the elevation of the lowest current meter

application of seismic interferometry by multidimensional deconvolution to ambient seismic noise recorded in malargue argentina obtaining new seismic responses from existing recordings is generally referred to as seismic interferometry si conventionally the si responses are retrieved by simple crosscorrelation of recordings made by separate receivers one of the receivers acts as a virtual source whose response is retrieved at the other receivers when si is applied to recordings of ambient seismic noise mostly surface waves are retrieved the newly retrieved surface wave responses can be used to extract receiver receiver phase velocities these phase velocities often serve as input parameters for tomographic inverse problems another application of si exploits the tempo ral stability of the multiply scattered arrivals of the newly retrieved surface wave responses temporal variations in the stability and or arrival time of these multiply scattered arrivals can often be linked to temporally varying parameters such as hydrocarbon production and precip itation for all applications however the accuracy of the retrieved responses is paramount correct response retrieval relies on a uniform illumination of the receivers irregularities in the illumination pattern degrade the accuracy of the newly retrieved responses in practice the illumination pattern is often far from uniform in that case simple crosscorrelation of separate receiver recordings only yields an estimate of the actual correct virtual source response re formulating the theory underlying si by crosscorrelation as a multidimensional deconvolution mdd process allows this estimate to be improved si by mdd corrects for the non uniform illumination pattern by means of a so called point spread function psf which captures the irregularities in the illumination pattern deconvolution by this psf removes the imprint of the irregularities on the responses obtained through simple crosscorrelation we apply si by mdd to surface wave data recorded by themalargue seismic array in western argentina the aperture of the array is approximately 60 km and it is located on a plateau just east of the andean mountain range the array has a t shape the receivers along one of the two lines act as virtual sources whose responses are recorded by the receivers along the other perpendicular line we select time windows dominated by surface wave noise travelling in a favourable direction that is traversing the line of virtual sources before arriving at the receivers at which we aim to retrieve the virtual source responses these time windows are selected through a frequency dependent slowness analysis along the two receiver lines from the selected time windows estimates of virtual source responses are retrieved by means of crosscorrelations similarly crosscorrelations between the positions of the virtual sources are computed to build the psf we use the psf to deconvolve the effect of illumination irregularities and the source function from the virtual source responses retrieved by crosscorrelation the combined effect of time window selection and mdd results in more accurate and temporally stable surface wave responses

comparison of optical and radar measurements of surf and swash zone velocity fields 1 surf zone bore celerities and swash zone surface currents were measured on a shallow sloping low energy beach using two remote sensing methods that differ fundamentally in their imaging mechanisms microwave doppler radar measures electromagnetic backscatter from small scale ocean surface roughness while video based particle image velocimetry piv relies on image texture resulting from variations in light reflectivity from the ocean surface imagery from the two methods showed high correlation in which regions of high radar backscatter corresponded to visibly identifiable waves and bores propagating across the surf zone correlation coefficients between radial velocity time series sampled using the two methods at multiple locations across the surf zone were typically greater than 0 5 for frequencies less than a noise cutoff of 0 25 hz similarly spectra were found to be coherent at the 95 level with a nearly zero phase shift between the two signals near the broad spectral peak between 0 02 and 0 25 hz however some significant differences were evident piv was capable of estimating both cross shore and alongshore surface velocities while the use of one microwave doppler radar system restricted surface velocity estimates from that technique to line of sight radial only piv was found to be more capable of estimating swash zone uprush and backwash surface velocities as a smoother water surface in the swash zone adversely affected radar reflectivity in contrast microwave doppler radar was found to be more capable of estimating the surface velocity between bores when insufficient image texture was recorded in the video imagery both techniques were capable of measuring surf zone bore celerities through comparison to a shallow water model and to independent celerity estimates extracted from the slope of individual bore trajectories typical normalized errors were roughly 25 for radar and 15 for piv

three dimensional geophysical anatomy of an active landslide in lias group mudrocks cleveland basin uk a geoelectrical investigation of a slow moving earth slide earth flow in lower jurassic lias group rocks of the cleveland basin uk is described these mudrock slopes are particularly prone to failure and are a major source of lowland landslides in the uk but few attempts have been made to spatially or volumetrically characterise the subsurface form of these slides the primary aim of this study was to consider the efficacy of fully three dimensional geoelectrical imaging for landslide investigation with reference to a geological setting typical of lias group escarpments the approach described here included a reconnaissance survey phase using two dimensional electrical resistivity tomography ert resistivity mapping self potential sp profiling and mapping followed by a detailed investigation of an area of the landslide using three dimensional 3d ert and self potential tomography spt interpretation of the geophysical data sets was supported by surface observations aerial lidar and differential gps geomorphological surveys and intrusive investigations boreholes and auger holes the initial phase of the study revealed the existence of a strong sp signature at the site consistent with a streaming potential source and established the relationships between the main geological units the geomorphologic expression of the landslide and the resistivity of the materials in and around the study area the 3d spt model generated during the second phase of the study indicated drainage patterns across the landslide and preferential flow from the low permeability mud rocks into the underlying more permeable sandstone formation because of favourable resistivity contrasts between the clay rich whitby mudstone formation landslide material and the underlying staithes sandstone formation the volumetric 3d ert image allowed a number of surface and subsurface landslide features to be identified and spatially located these included the lateral extent of slipped material and zones of depletion and accumulation the surface of separation and the thickness of individual earth flow lobes and the dipping in situ geological boundary between the whitby mudstone and staithes sandstone bedrock formations