modelling shoreface profile evolution current knowledge of hydro sediment and morpho dynamics in the shoreface environment is insufficient to undertake shoreface profile evolution modelling on the basis of first physical principles we propose a simple panel type model to map observed behaviour the internal dynamics are determined by slope dependent wave induced cross shoreface transports while the external driving factors are lateral sediment supply and sea level rise this model concept is tested with reasonable success against the observed behaviour of the central holland coast considering two hindcast periods one covering the evolution over the last century the other the subboreal subatlantic evolution a limitation of this model is that the cross shoreface dynamics are solely steered by the variations of shoaling short waves since a variety of other wave and current dynamics may be expected to be present in the coastal boundary layer it may well be that the effects of the mechanisms and conditions which are not represented are hidden in the coefficients of the sediment transport formula this limits the accuracy of the coefficients as used and our findings should be considered as an order of magnitude estimate only indeed behaviour oriented modelling implies that generalization of results to arbitrary situations and conditions is not straightforward yet we expect that some of the conclusions are more generally applicable this concerns the substantiation of the assumption that the upper shoreface responds on a much smaller time scale than the lower shoreface and the idea that the shoreface profile is not always and everywhere in equilibrium with its forcing a worthwhile observation from the holland coast application is that the bottom slope effect on the transport is only important at geological time scales the profile evolution at the engineering time scales say 10 to 100 years is effectively quasi static in that there is no feedback between the long term averaged transport and the state of the profile this implies that at these smaller scales the profile changes can be predicted on the basis of a static sediment balance this does not mean that the gravitational downslope transport is unimportant as a physical phenomenon in coastal profile evolution it is only unimportant if a highly aggregated model like this is applied at relatively short time scales

applicability of insar to tropical volcanoes insights from central america measuring volcano deformation is key to understanding the behaviour of erupting vol canoes and detecting those in periods of unrest satellite techniques provide the opportunity to do so on a global scale but with some notable exceptions the deformation of volcanoes in the tropics has been understudied relative to those at higher latitudes largely due to technical difficulties in applying interferometric synthetic aperture radar insar we perform a systematic survey of the central american volcanic arc to investigate the appli cability of interferometric synthetic aperture radar insar to volcanoes in the tropics volcano characteristics that may prevent insar measurement include 1 dense vegetation cover 2 per sistent activity and 3 steep slopes measurements of deformation are further inhibited by atmos pheric artefacts associated with 4 large changes in topographical relief we present a systematic method for distinguishing between water vapour artefacts and true deformation our data show a linear relationship c 2 cm km between the magnitudes of water vapour artefacts and volcano edifice height for high relief volcanoes e g fuego guatemala 3763 m a s l above sea level errors are of the order of 4 5 cm across the volcano s edifice but are less than 2 cm for lower relief e g masaya nicaragua 635 m a s l examples such as arenal atitlan and fuego illustrate that satellite acquisition strategies incorporating ascending and descending tracks are particularly important for studying steep sided volcanoes poor coherence is primarily associated with temporal decorrelation which is typically more rapid in southern central america where evergreen broadleaf vegetation dominates land use classification is a better predictorof decorrelation rate thanvegetationindex comparisonof coher ence for different radar wavelengths match expectations high resolution x band radar is best suited to local studies where high resolution digital elevation models dems exist while l bandwavelengths are necessary for regional surveys however this is the first time that relation ships between phase coherence and time perpendicular baseline radar wavelength and land use have been quantified on the scale of a whole volcanic arc

near real time radar interferometry of the mw 7 1 hector mine earthquake the hector mine earthquake mw 7 1 16 oc tober 1999 ruptured 45 km of previously mapped and un mapped faults in the mojave desert the ers 2 satellite imagedthemojavedeserton15septemberandagain on20 october just 4 days after the earthquake using a newly developed ground station we acquired both passes and were able to form an interferogram within 20 hours of the second overflight estimates of slip along the main rupture are 1 2 meters greater than slip derived from geological mapping the gradient of the interferometric phase reveals an inter esting pattern of triggered slip on adjacent faults as well as a 30 mm deep sink hole along interstate 40

formation of coastline features by large scale instabilities induced by high angle waves along shore sediment transport that is driven by waves is generally assumed to smooth a coastline this assumption is valid for small angles between the wave crest lines and the shore as has been demonstrated in shoreline models but when the angle between the waves and the shoreline is sufficiently large small perturbations to a straight shoreline will grow here we use a numerical model to investigate the implications of this instability mechanism for large scale morphology over long timescales our simulations show growth of coastline perturbations that interact with each other to produce large scale features that resemble various kinds of natural landforms including the capes and cuspate forelands observed along the carolina coast of southeastern north america wind and wave data from this area support our hypothesis that such an instability mechanism could be responsible for the formation of shoreline features at spatial scales up to hundreds of kilometres and temporal scales up to millennia

crustal deformation associated with an m8 1 earthquake in the solomon islands detected by alos palsar abstract on april 1 2007 utc a large mw 8 1 interplate earthquake struck the solomon islands subduction zone where complicated tectonics result from the subduction of four plates extensive ground movements and a large tsunami occurred in the epicentral area causing severe damage over a wide area using alos palsar data and the dinsar technique we detected crustal deformation exceeding 2 m in islands close to the epicenter a slip distribution of the inferred seismic fault was estimated using geodetic information derived from dinsar processing and field investigations the result indicates large slip areas around the hypocenter and the centroid it is possible that the largest slip area is related to subduction of the plate boundary between the woodlark and australian plates a small slip area between those large slip areas may indicate weak coupling due to thermal activity related to volcanic activity on simbo island the 2007 earthquake struck an area where large earthquake has not occurred since 1970 most of this seismic gap was filled by the 2007 events however a small seismic gap still remains in the southeastern region of the 2007 earthquake

the influence of tides wind and waves on the redistribution of nourished sediment at terschelling the netherlands abstract a calibrated morphodynamic model of the barrier island of terschelling the netherlands grunnet n m walstra d j r ruessink b g 2004 process based modelling of a shoreface nourishment coastal eng 51 7 581 607 comprising the island and its two adjacent tidal inlet systems is applied to identify the relative contribution of tides wind and waves to the cross shore and alongshore redistribution of a 2 mm3 nourishment supplied to the nearshore zone along the island several model simulations with varying combinations of horizontal and vertical tide wind and wave forcing were designed to investigate the effect of each individual forcing on a large spatio temporal scale order of kilometres and months respectively as expected stirring and transport by waves and wave induced currents are predicted to be by far the dominant contributor to the net sediment transport along the coast of terschelling because of the strong obliquity of the winds and the relatively small tidal currents in front of the island 0 5 m s alongshore wind driven currents increase sediment transport rates and horizontal tides virtually have no net transport capacity this motivated a local model of the study area along the closed coast of terschelling not including tidal inlets and further simplifying tidal boundary definitions by omitting the horizontal tides morphodynamic simulations of the local model show virtually identical results as the larger model predictions the reduction in complexity in setting up a local model instead of a regional model coupled with the corresponding significant reduction in computational time points to an increasing applicability of complex process based models

decorrelation in interferometric radar echoes a radar interferometric technique for topographic mapping of surfaces implemented utilizing a single synthetic aperture radar sar system in a nearly repeating orbit is discussed the authors characterize the various sources contributing to the echo correlation statistics and isolate the term which most closely describes surficial change they then examine the application of this approach to topographic mapping of vegetated surfaces which may be expected to possess varying backscatter over time it is found that there is decorrelation increasing with time but that digital terrain model generation remains feasible the authors present such a map of a forested area in oregon which also includes some nearly unvegetated lava flows such a technique could provide a global digital terrain map

nourishing the shoreface observations and hindcasting of the egmond case the netherlands abstract although beach nourishment policy in the netherlands is generally successful in maintaining the 1990 shoreline the efficiency of nourishments at several locations along the north sea coast is unacceptably low these locations are identified as erosion hotspots egmond aan zee is such a hotspot the bathymetric longshore irregularities make this coastal stretch highly susceptible to rip currents and horizontal circulations which transport large volumes of nourished sand to the sea in 1999 an alternative nourishment design was implemented this consisted of a shoreface nourishment at the outer bar at 7 5 m depth combined with a nourishment of the beach behind it high resolution bathymetric surveys carried out with the wesp revealed that the shoreface nourishment resulted in a significant shoreward migration of the outer bar during 1999 2001 after 2 years the system started to return to its natural dynamic equilibrium and lost the positive influence of the shoreface nourishment area shoreward movement of bars and increase of bar height which forms the first defense line of the mainland against the sea and positive contribution to the sand budget which increased as a result of the nourishment after 3 years may 1999 to april 2002 the sediment volume still had an increase of 477 500 m3 45 of the applied sand relative to may 1999 the shoreface nourishment area did not have a direct effect on the beach the shoreface nourishment area probably will have to be maintained to retain the sediment on the beach in the long run in egmond the shoreface nourishment started to disappear before the sediment could reach the beach the time scale of sediment feed to the beach zone probably is of the order of 5 10 years the shoreface nourishment seems to function as a reef creating a lee side effect that influences both cross shore and longshore sediment transport resulting in two main hypotheses firstly the longshore effect in which large waves break at the shoreface nourishment cause a calmer wave climate shoreward of the shoreface nourishment area and a reduction of the longshore current the shoreface nourishment partially blocks the wave driven longshore current secondly the cross shore effect in which shoaling waves generate onshore transport these hypotheses are supported by generated model results with both a process based profile model unibest tc and a process based coastal area model delft3d mor the unibest tc model was able to predict the detachment of the outer bar from the shoreface nourishment and to some extent the shoreward bar movements in the lee of the shoreface nourishment area the model found an increase in sediment confirming the shielding effect of the shoreface nourishment area the delft3d model found as a result of the shoreface nourishment area a decrease of the flow velocity and the wave height just shoreward of the shoreface nourishment area the model was able to predict the similar trend in sedimentation erosion pattern although the intensities were smaller in the lee of the shoreface nourishment area a clear sedimentation was found erosion was found south and seaward of the shoreface nourishment area the modeled profiles did not follow the measured profile changes the separation of the shoreface nourishment from the outer bar and the shoreward migration of the bars could not be accurately modeled because the cross shore transport caused by wave asymmetry is not taken into account in the standard version of delft3d these results were in line with the expectations

surface deformation and coherence measurements of kilauea volcano hawaii from sir c radar interferometry the shuttle imaging radar c x synthetic aperture radar sir c x sar radar on board the space shuttle endeavor imaged kilauea volcano hawaii in april and october 1994 for the purpose of measuring active surface deformation by the methods of repeat pass differential radar interferometry observations at 24 cm l band and 5 6 cm c band wavelengths were reduced to interferograms showing apparent surface deformation over the 6 month interval and over a succession of 1 day intervals in october a statistically significant local phase signature in the 6 month interferogram is coincident with the pu u o o lava vent interpreted as deformation the signal implies centimeter scale deflation in an area several kilometers wide surrounding the vent peak deflation is roughly 14 cm if the deformation is purely vertical centered southward of the pu u o o caldera delays in the radar signal phase induced by atmospheric refractivity anomalies introduce spurious apparent deformation signatures at the level of 12 cm peak to peak in the radar line of sight direction though the phase observations are suggestive of the wide area deformation measured by global positioning system gps methods the atmospheric effects are large enough to limit the interpretation of the result it is difficult to characterize centimeter scale deformations spatially distributed over tens of kilometers using differential interferometry without supporting simultaneous spatially distributed measurements of refractivity along the radar line of sight studies of the interferometric correlation of images acquired at different times show that l band is far superior to c band in the vegetated areas even when the observations are separated by only 1 day these results imply longer wavelength instruments are more appropriate for studying surfaces by repeat pass observations

the morphodynamic modelling of tidal sand waves on the shoreface an artificial sand wave on the dutch shoreface of the north sea has been studied in conditions with relatively strong tidal currents in the range of 0 5 to 1 m s and sediments in the medium sand size range of 0 2 to 0 5 mm the sand wave is perpendicular to the tidal current and has a maximum height and length of the order of 5 m and 1 km respectively the sand wave is dynamically active and shows migration rates of the order of a few metres per year a numerical morphodynamic model delft3d model has been used to simulate the morphological behaviour of the sand wave in the north sea this model approach is based on the numerical solution of the three dimensional shallow water equations in combination with a surface wave propagation model wind waves and the advection diffusion equation for the sediment particles with online bed updating after each time step the model results show that the sand wave grows in the case of dominant bed load transport weak tidal currents relatively coarse sediment small roughness height low waves and that the sand wave decays in the case of dominant suspended transport strong currents relatively fine sediment large roughness height storm waves

satellite radar interferometry for monitoring ice sheet motion application to an antarctic ice stream satellite radar interferometry sri provides a sensitive means of monitoring the flow velocities and grounding line positions of ice streams which are indicators of response of the ice sheets to climatic change or internal instability the detection limit is about 1 5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction the grounding line detected by tidal motions where the ice goes afloat can be mapped at a resolution of 0 5 kilometer the sri velocities and grounding line of the rutford ice stream antarctica agree fairly well with earlier ground based data the combined use of sri and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior

satellite radar interferometric map of the coseismic deformation field of the m 6 1 eureka valley california earthquake of may 17 1993 interferometric combination of pairs of synthetic aperture radar sar images acquired by the ers 1 satellite before and after the eureka valley california earthquake of may 17 1993 maps the coseismic deformation field the fringes corresponding to contours of equal change in satellite to ground distance can be enhanced by forming the sum of two of such interferograms with altitudes of ambiguity roughly equal in magnitude but opposite in sign the resulting composite interferogram reveals some 10 cm of change in range indicating a coseismic deepening of the eureka valley graben after unwrapping filtering and decimation the range changes are used to estimate the centroid and focal mechanism these estimates indicate normal faulting on a rupture patch compatible with the distribution of aftershocks and mapped quaternary faults the change in elevation produced by this earthquake resembles the current topography scaled by a factor of 20 000

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

the influence of shelf indenting canyons and infralittoral prograding wedges on coastal morphology the carchuna system in southern spain abstract submarine canyons and progradational sedimentary bodies are common features of continental margins worldwide few studies have analyzed the relationship between the coastal morphology and the morphology and sedimentary characteristics of the adjacent shelf in wave dominated coasts or the potential role played by shelf indenting canyons as inducers of sediment deposition in shallow waters this work presents a study that correlates the coastal morphology with the characteristics of the adjacent offshore shallow shelf in an area with a complex inner bathymetry the carchuna system spain the study area is characterized by large scale non rhythmic cuspate features in the coastline whereas the inner bathymetry exhibits a shallow water infralittoral prograding wedge ipw and a shelf indenting canyon that has tributaries located a short distance from the coastline using detailed bathymetric measurements observational data and wave propagation modeling the influence of the different bathymetric elements was quantified and a mechanism proposed for the generation of the carchuna ipw the wave propagation results show that the canyon is the main source of the alongshore modulation of nearshore waves and that it plays a major role in the generation of the large scale cuspate features in the shoreline additionally these results suggest that the long term coastal erosion associated with extreme storms yielded sufficient sediment which when subsequently transported eastward the dominant littoral drift direction formed the ipw once formed the ipw modified the wave propagation patterns and contributed to the development and reinforcement of the shoreline features

from river to shelf anatomy of a high frequency depositional sequence the late pleistocene to holocene tiber depositional sequence the late pleistocene holocene tiber delta succession represents the most recent and one of the best preserved high frequency low rank depositional sequences developed along the latium continental margin of the italian peninsula several previous studies have established a robust data set from which it has been possible to describe the stratigraphic architecture of the entire tiber depositional sequence from the landward to seaward sectors and over a distance of 60 km the tiber depositional sequence shows many characteristics found in other late pleistocene to holocene deltaic and coastal successions of the mediterranean area the stratigraphic architecture of the tiber depositional sequence is controlled mainly by glacioeustasy although factors such as tectonic uplift volcanism and subsidence exert an influence at a local scale the resulting depositional model allowed discussion of some important points such as 1 the genesis of the tiber mixed bedrock alluvial valley extending from the coastal plain to the innermost portion of the shelf recording i multiple episodes of incision during relative sea level fall and ii a downstream increase of depth and width of the valley during the base level fall and the subsequent base level rise 2 the different physical expression of the tiber depositional sequence boundary from landward to seaward and its diachronous and composite character 3 the maximum depth reached by the tiber early lowstand delta at the end of the sea level fall is estimated at ca 90 m below the present sea level and not at 120 m as suggested by previous works 4 the backward position of the tiber late lowstand delta relative to the deposit of early lowstand 5 the change of the channel pattern and of the stacking pattern of fluvial deposits within the lowstand systems tract transgressive systems tract and highstand systems tract all of these features indicate that the late pleistocene holocene tiber delta succession even if deposited in a short period of time from a geological point of view represents the result of the close interaction among many autogenic and allogenic factors however global eustatic variations and sediment supply under the control of climatic changes can be considered the main factors responsible for the stratigraphic architecture of this sedimentary succession which has been heavily modified by human activity only in the last 3000 years

rapid deformation of the south flank of kilauea volcano hawaii the south flank of kilauea volcano has experienced two large magnitude m 7 2 and m 6 1 earthquakes in the past two decades global positioning system measurements conducted between 1990 and 1993 reveal seaward displacements of kilauea9s central south flank at rates of up to about 10 centimeters per year in contrast the northern side of the volcano and the distal ends of the south flank did not displace significantly the observations can be explained by slip on a low angle fault beneath the south flank combined with dilation deep within kilauea9s rift system both at rates of at least 15 centimeters per year

processes controlling the development of a river mouth spit abstract spits are among the most dynamic features in the coastal zones their stability is very often the result of a fragile equilibrium between the availability of sediments and the forcing hydrodynamics due to the complex interactions between the processes shaping such geomorphologic features the investigation is difficult and requires separate analysis for each of the processes a typical example of a spit is sahalin which emerged one century ago at the mouth of the danube delta s southernmost distributary and has continuously evolved through elongation and lateral migration in order to investigate and quantify separately each of the main processes shaping a spit we divide our research in two stages first wave induced sediment transports were simulated and analyzed using a complex processes based on a numerical model for an idealised spit this schematized spit was based on the shape of a number of spits secondly the findings were used in a similar approach for a real case the sahalin spit results show convergence of the wave fields towards the spit and large transport rates for the dominant wave directions the sediment budget derived from the predicted transport and the historical maps of the spit show that the evolution of the spit is the result of a continuous interaction between along and cross shore sediment transport furthermore a good match was obtained between the volumes of sediment supplied to the spit system and those feeding the expansion of the spit the final output is a conceptual model that includes four stages submarine accumulation emerging evolution and merging with the mainland of the spit based on the findings from the present study as well as on the findings of previous authors although the model was constructed to explain the evolution of sahalin spit it is suggested that it can be applied more generally for spits formed in wave dominated deltas in a microtidal environment and with a wave climate dominated by one direction

phase gradient approach to stacking interferograms the phase gradient approach is used to construct averages and differences of interferograms without phase unwrapping our objectives for change detection are to increase fringe clarity and decrease errors due to tropospheric and ionospheric delay by averaging many interferograms the standard approach requires phase unwrapping scaling the phase according to the ratio of the perpendicular baseline and finally forming the average or difference however unique phase unwrapping is usually not possible since the phase gradient due to topography is proportional to the perpendicular baseline phase unwrapping is unnecessary prior to averaging or differencing phase unwrapping may be needed to interpret the results but it is delayed until all of the largest topographic signals are removed we demonstrate the method by averaging and differencing six interferograms having a suite of perpendicular baselines ranging from 18 to 406 m cross spectral analysis of the difference between two tandem interferograms provides estimates of spatial resolution which are used to design prestack filters a wide range of perpendicular baselines provides the best topographic recovery in terms of accuracy and coverage outside of mountainous areas the topography has a relative accuracy of better than 2 m residual interferograms single interferogram minus stack have tilts across the unwrapped phase that are typically 50 mm in both range and azimuth reflecting both orbit error and atmospheric delay smaller scale waves with amplitudes of 15 mm are interpreted as atmospheric lee waves a few global positioning system gps control points within a frame could increase the precision to 20 mm for a single interferogram further improvements may be achieved by stacking residual interferograms

holocene evolution of the danube delta an integral reconstruction and a revised chronology abstract the danube delta is one of the few large deltas in the world the evolution of which has involved numerous and varied episodes within a complex framework of interactivity between river sediment supply allochthonous sediments supplied by longshore currents marine dispersing forces vertical movements neotectonics sediment compaction and sea level the resulting complex morphology comprises diversified landscapes varying from labyrinthic net of channels and lakes fluvial delta to massive tracts of monotonous reed marshes large lagoons divided by barriers or beach ridge plains accommodating large transgressive dunefields maritime delta whilst previous studies have focused on various sectors of the danube delta the current paper proposes for the first time an integral reconstruction of delta evolution based on existing and new sedimentological and morphological analyses and absolute ages ams 14 c and osl enabling a comprehensive synthesis in terms of both evolutionary phases and growth patterns a chronological framework was established for all the deltaic lobes and beach ridge plains highlighting the relationship between formation timespan growth rates and the resultant morphology this work unveils the early stage of delta formation including the reconstruction of delta front advancement into danube bay old danube lobe prior to 7 5 5 5 ka and initial spit barrier development 6 7 6 5 5 8 ka inception of the bayhead delta started 1000 yr before the relative stabilization of sea level and of the initial spit formation the original fluvial delta plain topography is now buried at a depth of 4 6 m depth below the present topography representing the current stage of fluvial aggradation as a result of subsidence and sea level rise regarding the maritime delta six large open coast lobes developed in the last six millennia of which four were formed by the sf gheorghe branch attesting the long uninterrupted activity of this branch whereas the other two were created respectively by the sulina and the chilia branches the evolution of each lobe is derived from successive chronological shoreline positions and discussed in relation with changes in danube discharge special attention has been paid to their growth stages and progradation rates for the southern delta we bring in new arguments for an active southern distributary the dunav derived from the sf gheorghe branch that formed successive open coast lobes between 2 6 and 1 3 ka additionally we discuss the effects of modern anthropogenically driven fluvial sediment reduction on the morphology and morphodynamics of the active lobes of the danube

two new conceptual models for the formation and degradation of baymouth spits by longshore drift and fluvial discharge iguape se brazil this study describes the formation of two successive baymouth spits systems on the southeastern brazilian coast and the degradation of the first system the study area includes the jureia beach spit the deflected ribeira de iguape river mouth the central iguape sandy headland the icapara inlet of the mar pequeno lagoon and the northern end of the comprida island barrier spit the wave and river flow patterns were combined with the coastline evolution and the alongshore migration rates deduced from satellite images initially both spits showed convergent alongshore migration rates equal to or less than 83 m y however the extreme river flow due to high rainfall during a very strong el nino event in 1983 eroded the inland side of the jureia beach spit which finally retreated due to wave erosion in 1989 a sand bank emerged in the river mouth which attached to the central headland forming a recurved northeastward spit in 1994 the high fluvial discharge associated with another very strong el nino event caused the landward migration of the new spit and emersion of a second sand bank this second sand bank merged with the jureia beach spit in 1997 at an alongshore migration rate of 1 795 6 m y wave erosion of the central headland continued and the attached spit disappeared in 2000 in 2009 the headland erosion merged the river mouth and the icapara inlet which resulted in flanking baymouth spits in a configuration that remains today therefore two models for the formation of baymouth spits have been documented for wave dominated microtidal coasts in humid tropical regions with intense fluvial discharge the convergent longshore migration of the spits is controlled by both the bidirectional longshore drift and the fluvial discharge the latter eroding the fronting spit supplying sediments and acting as a hydraulic blockage for longshore drift

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

integrated satellite interferometry tropospheric noise gps estimates and implications for interferometric synthetic aperture radar products interferometric synthetic aperture radar insar like other astronomic and space geodetic techniques is limited by the spatially and temporally variable delay of electromagnetic waves propagating through the neutral atmosphere statistical analysis of these variations from a wide variety of instruments reveals a power law dependence on frequency that is characteristic of elementary kolmogorov turbulence a statistical model for a major component of the delay fluctuations the wet component has previously been developed by treuhaft and lanyi 1987 for very long baseline interferometry a continuous global positioning system gps network is now in place in southern california that allows estimation of along with geodetic parameters the total delay due to the atmosphere above each site on a subhourly basis these measurements are shown to conform to the treuhaft and lanyi tl statistical model both temporally and spatially the tl statistical model is applied to the problem of insar and used to produce the covariance between two points separated in time and or space the error due to the atmospheric variations for sar products such as topography and surface deformation is calculated via propagation of errors there are two methods commonly cited to reduce the effect of atmospheric distortion in products from sar interferometry stacking and calibration stacking involves averaging independent interferograms to reduce the noise calibration involves removing part or all of the delay using data from an independent source such as total zenith delay estimates from continuous gps networks despite the relatively poor spatial density of surface measurements calibration can be used to reduce noise if the measurements are sufficiently accurate reduction in tropospheric noise increases with increasing number of measurement points and increasing accuracy up to a maximum of n where n is the number of points stacking and calibration are shown to be complementary and can be used simultaneously to reduce the noise to below that achievable by either method alone

young danube delta documents stable black sea level since the middle holocene morphodynamic paleogeographic and archaeological implications new radiocarbon and optical dates show that the holocene danube delta started to build out of a black sea embayment 5200 yr ago delta lobe development phases differ by as much as 5 k y from previously proposed ages the new chronology allows for a better understanding of the danube delta paleogeography includ ing the demise of istria the main ancient greek roman city in the region prior reconstructions of sea level in the black sea inferred fluctuations to 15 m in range however stratigraphy of beach ridg es in the delta shows that the relative black sea level for the past 5 k y was stable in the danube delta region within 2 m and 1 5 of the current level hydroisostatic effects related to a proposed catastrophic reconnection of the black sea to the world ocean in the early holocene may have been responsible for the sea level reaching the highstand earlier than estimated by models the new sea level data suggest that submergence at several ancient settle ments around the black sea may be better explained by local fac tors such as subsidence rather than by basin wide sea level fluctuations

sediment budget of the rhone delta shoreface since the middle of the 19th century this study analyses long term 1841 1872 1895 1974 changes in the grand rhone prodeltaic lobe to 1 quantify the accumulation 2 determine the evolution of relict prodeltaic lobes and 3 establish long term relationships between river sediment discharge the shoreface and the continental shelf our results show a reduction of the sedimentation of the prodeltaic lobe at the main river mouth since 150 yr by a factor of 3 7 12 63 to 3 41 10 6 m 3 yr 1 at the minor mouth of the river erosion dominates and speeds up during the same period 0 53 to 1 34 10 6 m 3 yr 1 these changes are found to directly result from the river sediment input decrease related to the natural decreasing of the frequency of major floods end of the little ice age the reforestation in the catchment area the dam construction and the dredging activities since the 1950s our results indicate that while there is large sediment accumulation in the area around a growing prodeltaic lobe there is also a reduced contribution of the river sediments to the non adjacent beaches of the mouth following a shift in the river channel and mouth the relict prodeltaic lobes petit rhone st ferreol bras de fer and pegoulier are reworked by waves and their sediments contribute partially to the growth of the spits espiguette beauduc and gracieuse this suggests that there is a time shift between the input of river sediment to the sea and the build up of a beach the chronic erosion of the coastline is likely to continue in the future since 1 a river shift is not possible because the river channels are controlled by dykes and human intervention 2 the decrease of river sediment input and 3 the relict prodeltaic lobes constitute sedimentary reservoirs that are gradually being used up 2006 published by elsevier b v

analysis of active lava flows on kilauea volcano hawaii using sir c radar correlation measurements precise eruption rates of active pahoehoe lava flows on kilauea volcano hawaii have been determined using spaceborne radar data acquired by the space shuttle imaging radar c sir c a coastal site downslope from the pu9u o9o vent was imaged once per day on each of the four days of october 7 10 1994 day to day decorrelation due to resurfacing was determined by interferometric combination of the data at 15 m resolution over a wide area on successive days new lava resurfaced 335700 m 2 368775 m 2 and 356625 m 2 assuming an average pahoehoe flow thickness of 50 cm a mean effusion rate for this period is approximately 2 m 3 s the radar observations show persistent surface activity at each site rather than downslope migration of coherent lava flows

hardgrounds reworked concretion levels and condensed horizons in the jurassic of western india their significance for basin analysis jurassic sediments in the shallow pericratonic basins of kachchh and rajasthan western india exhibit numerous signs of reduced sedimentation omission erosion and in situ reworking in combination with synsedimentary cementation hardgrounds developed on carbonate shoals in the bathonian of rajasthan whilst reworked concretion levels are characteristic of offshore siliciclastic sediments of the callovian of kachchh a prominent marker horizon the oxfordian dhosa oolite member occurs throughout much of the kachchh sub basin and is a highly condensed unit characterized by hardgrounds intraformational cobbles reworked concretions stromatolitic iron crusts iron oncoids and shell lags hardgrounds reworked concretion levels and condensation horizons are interpreted as the preserved relicts of transgressive pulses such pulses were possibly controlled by eustatic rise of sea level of at least equal importance however was a tectonic control which is demonstrated by the presence of small neptunian dykes boulder beds derived from small submarine cliffs and rapid lateral facies and thickness changes in the dhosa oolite member these indications of extensional tectonics are thought to be connected to rifting and initial sea floor spreading between africa and india

post wildfire surface deformation near batagay eastern siberia detected by l band and c band insar thawing of ice rich permafrost and subsequent ground subsidence can form characteristic landforms and the resulting topography they create are collectively called thermokarst the impact of wild

danube river sediment input and its interaction with the north western black sea abstract the influence of the river danube is determinant to the sedimentation of the north western and western black sea area after 1970 following the building of the iron gates dam the danube river sediment discharge diminished to 30 40 of its previous value after a 12 000 year evolution marked by active progradation the danube delta has become mainly inactive over the last few decades partly due to interventions of man made origin the deficit of sediment influx has led to the intense erosional processes of the deltaic littoral on the black sea north western shelf two main areas with contrasting sedimentary processes have been identified the internal danube sediment fed shelf and the external sediment starved shelf the modern highstand sedimentary history of the north western black sea deep area is marked by the cessation of the danube deep sea fan active development the main depositional units within the north western black sea are described

modelling the morphology of sandy spits abstract the shape dimensions and growth rate of an accumulating sandy spit is investigated by a theoretical and experimental study the idealised case of a spit growing without change of form under a constant wave forcing is considered the longshore wave driven sediment transport is taken to be dominant in the formation of the spit the shape of the spit is first described by an analytical one line model for the coastline development and by a simple littoral drift model the analytical model is valid for a spit with so large dimensions that quasi uniform conditions can be applied it is found that with this assumption the dimensions of the spit cannot be determined the width and shape of a finite spit is therefore determined from simulations with an area model for the wave driven current and sediment transport along the spit in this case the curvature effects from the spit on the longshore sediment transport inertia of the longshore current wave focussing are includes several solutions for a uniformly growing spit may exist and it is assumed that the fastest growing spit is the one to emerge the simulations indicate the width of the spit to be proportional to the width of the surf zone in experiments conducted in a wave tank an accumulating spit was formed at the down drift end of a uniform stretch of coast exposed to waves approaching at an angle the spit approached equilibrium dimensions when a constant wave climate was applied the radius of curvature of the spit varied according to the height of the incoming waves

seasonal scale nearshore morphological evolution field observations and numerical modeling abstract a coupled waves currents bathymetric evolution model delft 3d is compared with field measurements to test hypotheses regarding the processes responsible for alongshore varying nearshore morphological changes at seasonal time scales a 2001 field experiment along the beaches adjacent to grays harbor washington usa captured the transition between the high energy erosive conditions of winter and the low energy beach building conditions typical of summer the experiment documented shoreline progradation on the order of 10 20 m and on average approximately 70 m of onshore sandbar migration during a four month period significant alongshore variability was observed in the morphological response of the sandbar over a 4 km reach of coast with sandbar movement ranging from 20 m of offshore migration to over 175 m of onshore bar migration the largest seasonal scale onshore migration event observed in a natural setting both observations and model results suggest that in the case investigated here alongshore variations in initial bathymetry are primarily responsible for the observed alongshore variable morphological changes alongshore varying incident hydrodynamic forcing occasionally significant in this region due to a tidal inlet and associated ebb tidal delta was relatively minor during the study period and appears to play an insignificant role in the observed alongshore variability in sandbar behavior at kilometer scale the role of fully three dimensional cell circulation patterns in explaining the observed morphological variability also appears to be minor at least in the case investigated here

a long term decadal scale evolution model for microtidal barrier systems abstract a model is presented to simulate the long term decadal evolution of microtidal spit barrier systems the model has been derived from the analysis of coastal processes taking place along the trabucador la banya complex in the ebro delta spanish mediterranean coast it is composed of two submodels to simulate the evolution of the seaside and bayside barrier shorelines the outer coast submodel is of the one line type but formulated in curvilinear coordinates to reproduce the evolution of strongly curved coasts which is a common configuration for spits the model makes use of a long term parameterization of the longshore sediment transport rate which is formulated in terms of a morphological wave and a local transport constant the inner coast submodel is based on a morphological equilibrium approach it considers the overwash transport to be the dominant driving term contributing to the sediment budget of the inner coast it makes use of the concept of critical barrier width to estimate the conditions under which overwash is able to contribute to bayside shoreline accretion the model has been verified calibrated for the trabucador la banya system and it has been used to simulate its evolution under different climatic scenarios

barrier formation on an actively prograding delta system the red river delta vietnam abstract an extensive barrier spit system 20 to 30 km long developed on the delta front platform of the ba lat delta within a relatively short period 10 20 years however it was not evident whether the formation was related to river floods typhoons or calm weather conditions or to cross shore or alongshore sediment transport mechanisms therefore a process based numerical model that simulates sediment transport and morphologic changes by waves tides wind and river flow is used to analyze the processes that govern this barrier formation the mechanism that initiates the barrier formation is concluded to be onshore transport by wave asymmetry of sediment previously transported seaward in the buoyant river plume the main mechanism that counteracts the barrier formation is probably destruction of the barrier by river flow during the subsequent transformation from a subaqueous barrier into a sub aerial barrier spit system overwashes and alongshore sediment transport become increasingly important this spit system therefore appears to be dominated by alongshore processes even though its initial formation is more strongly regulated by cross shore processes the importance of cross shore processes results in a minor contribution of typhoons to the initial formation of these barriers typhoons are not very important to destruction of barriers as well because wave energy is gradually dissipated over the gentle offshore profile which in turn results from river plume sedimentation

accuracy of topographic maps derived from ers 1 interferometric radar an interferometric radar technique for topographic mapping of surfaces promises a high resolution approach to the generation of digital elevation models the authors present analyses of data collected by the synthetic aperture radar instrument on board the ers 1 satellite on successive orbits use of a single satellite in a nearly repeating orbit is attractive for reducing cost and spaceborne hardware complexity also it permits inference of changes in the surface from the correlation properties of the radar echoes the data have been reduced to correlation maps and digital elevation models the correlation maps show that temporal correlation decreases significantly with time but not necessarily at a constant well defined rate likely depending on environmental factors when correlation among passes remains high however it is possible to form digital elevation models analyses of noise expected in ers 1 interferometric data collected over alaska and the southwestern united states indicate that maps with relative errors less than 5 m rms are possible in some regions however orbit uncertainties imply that tie points are required in order to reduce absolute height errors to a similar magnitude the authors find that about 6 tie points per 40 spl times 40 km scene with 5 m rms or better height accuracy are needed to keep systematic map height errors below 5 m rms the performance of the ers 1 radar system for topographic applications though useful for a variety of regional and local discipline studies may be improved with respect to temporal decorrelation errors and absolute height acuity by modifying the orbit repeat period and incorporating precise orbit determination techniques the resulting implementation will meet many but not all objectives of a global mapping mission

atmospheric limitations to repeat track radar interferometry in its recent radar imaging mission the shuttle imaging radar satellite sir c devoted three days to repeat track interferometry we have analyzed the data from a test site in the mojave desert of california although good topography 10 m on 21 m postings was obtained most of the error was caused by turbulent water vapor in the lower atmosphere spatial structure of 6 km and all smaller sizes was observed the rms one way time delay was found to be 0 24 cm essentially identical results were obtained at two wavelengths 24 and 5 7 cm

the lowest place on earth is subsiding an insar interferometric synthetic aperture radar perspective since the early 1990s sinkholes and wide shallow subsidence features wssfs have become major problems along the dead sea shores in israel and jordan sinkholes are readily observed in the field but their locations and timing are unpredictable wssfs are often difficult to observe in the field however once identified they delineate zones of instability and increasing hazard in this study we identify characterize and measure rates of subsidence along the dead sea shores by the interferometric synthetic aperture radar insar technique we analyze 16 sar scenes acquired during the years 1992 to 1999 by the european remote sensing ers 1 and ers 2 satellites the interferograms span periods of between 2 and 71 months wssfs are observed in the lisan peninsula and along the dead sea shores in a variety of appearances including circular and elongate coastal depressions a few hundred meters to a few kilometers in length depressions in ancient alluvial fans and depressions along salt diapir margins phase differences measured in our interferograms correspond to subsidence rates generally in the range of 0 20 mm yr within the studied period with exceptional high rates that exceed 60 mm yr in two specific regions during the study period the level of the dead sea and of the associated ground water has dropped by 6 m this water level drop within an aquifer overlying fine grained marly layers would be expected to have caused aquifer system consolidation resulting in gradual subsidence comparison of our insar observations with calculations of the expected consolidation shows that in areas where marl layers are known to compose part of the upper 30 m of the profile estimated consolidation settlements are of the order of the measured subsidence our observations also show that in certain locations subsidence appears to be structurally controlled by faults seaward landslides and salt domes gradual subsidence is unlikely to be directly related to the sinkholes excluding the use of the wssfs features as predictable precursors to sinkhole formation

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

a numerical shoreline model for shorelines with large curvature abstract this paper presents a new numerical model for shoreline change which can be used to model the evolution of shorelines with large curvature the model is based on a one line formulation in terms of coordinates which follow the shape of the shoreline instead of the more common approach where the two orthogonal horizontal directions are used the volume error in the sediment continuity equation which is thereby introduced is removed through an iterative procedure the model treats the shoreline changes by computing the sediment transport in a 2d coastal area model and then integrating the sediment transport field across the coastal profile to obtain the longshore sediment transport variation along the shoreline the model is used to compute the evolution of a shoreline with a 90 change in shoreline orientation due to this drastic change in orientation a migrating shoreline spit develops in the model the dimensions of the spits evolving in the model compare favorably to previous model results and to field observation of the skaw spit in the north of denmark

surface displacement of the 17 may 1993 eureka valley california earthquake observed by sar interferometry satellite synthetic aperture radar sar interferometry shows that the magnitude 6 1 eureka valley earthquake of 17 may 1993 produced an elongated subsidence basin oriented north northwest parallel to the trend defined by the aftershock distribution whereas the source mechanism of the earthquake implies a north northeast striking normal fault the 3 millimeter accuracy of the radar observed displacement map over short spatial scales allowed identification of the main surface rupture associated with the event these observations suggest that the rupture began at depth and propagated diagonally upward and southward on a west dipping north northeast fault plane reactivating the largest escarpment in the saline range

on the derivation of coseismic displacement fields using differential radar interferometry the landers earthquake we present a map of the coseismic displacement field resulting from the landers california june 28 1992 earthquake derived using data acquired from an orbiting high resolution radar system we achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques data from the ers 1 synthetic aperture radar instrument acquired in april july and august 1992 are used to generate a high resolution wide area map of the displacements the data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30 m resolution element in a 113 km by 90 km image our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing comparison of these data with global positioning system and electronic distance measurement survey data yield a correlation of 0 96 thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format the technique we use is 1 more automatic 2 more precise and 3 better validated than previous similar applications of differential radar interferometry since we require only remotely sensed satellite data with no additional requirements for ancillary information the technique is well suited for global seismic monitoring and analysis

complex crustal deformation of the 2016 kaikoura new zealand earthquake revealed by alos 2complex crustal deformation of the 2016 kaikoura new zealand earthquake revealed by alos 2

mechanics of river mouth bar formation implications for the morphodynamics of delta distributary networks 1 in this paper we use observational data and numerical modeling to present a new explanation for the formation of river dominated delta networks observational data from deltas throughout the world show that distributary channel widths depths and lengths decrease nonlinearly with successive bifurcations trends in width and depth are an outcome of hydraulic geometry scaling the trend in channel length is a consequence of delta growth analyses of serial maps show that the positions of bifurcations are the fossilized locations of river mouth bars also called middle ground and distributary mouth bar in front of old delta channel mouths therefore the trend in channel length can be explained through the mechanics of river mouth bar formation and evolution we use delft3d a coupled hydrodynamic and morphodynamic model to simulate the process of river mouth bar formation within an expanding turbulent jet in front of distributary channel mouths our results describe in detail the formation and evolution of a river mouth bar system and demonstrate that the distance to the river mouth bar is proportional to jet momentum flux and inversely proportional to grain size therefore channel length decreases down delta because with each successive bifurcation the jet momentum flux decreases these results can be used to predict the future evolution of river dominated deltas and can be used to aid in hydrocarbon exploration of these depositional environments

wave climate coastal sediment budget and shoreline changes for the danube delta abstract since its formation approximately 12 000 years ago the coastal zone of the danube delta experienced alternating periods of accretion and erosion related to the natural process of lobe abandonment caused by river avulsion over the last 150 years the effects of human interventions modified these natural trends regulation of the danube river e g the iron gates barrages facilitating navigation and controlling river discharge construction and extension of the sulina entrance jetties and dredging of the sulina mouth bar for navigational purposes are examples of human interventions that influenced and still influence the actual state of the danube delta coastal zone most importantly these interventions diminished the quantity of sediments reaching the coast and consequently led to a severe retreat of the shoreline especially in the sulina sf gheorghe coastal sector to investigate and quantify the recent sediment budget and associated shoreline changes along the danube delta coastal zone we constructed a hindcast of the wave climate the alongshore transport capacity and the resulting sediment budget using a numerical coastline model on a local scale it was found that overwash plays an important role i e the observed evolution of sahalin spit island shows a cross shore landward migration that is much larger than could be explained by the calculated alongshore sediment transport gradients on a delta scale however the resulting alongshore sediment transport gradients and associated sediment budgets comply very well with the observations confirming the dominant role of wave induced alongshore transport and giving confidence in our predictions regarding the shoreline position for the next 25 and 50 years the results of this study indicate the potential for broader applicability of the model to other deltas especially those in wave dominated settings

estimating lava volume by precision combination of multiple baseline spaceborne and airborne interferometric synthetic aperture radar the 1997 eruption of okmok volcano alaska interferometric synthetic aperture radar insar techniques are used to calculate the volume of extrusion at okmok volcano alaska by constructing precise digital elevation models dems that represent volcano topography before and after the 1997 eruption the posteruption dem is generated using airborne topographic synthetic aperture radar topsar data where a three dimensional affine transformation is used to account for the misalignments between different dem patches the preeruption dem is produced using repeat pass european remote sensing satellite data multiple interferograms are combined to reduce errors due to atmospheric variations and deformation rates are estimated independently and removed from the interferograms used for dem generation the extrusive flow volume associated with the 1997 eruption of okmok volcano is 0 154 spl plusmn 0 025 km sup 3 the thickest portion is approximately 50 m although field measurements of the flow margin s height do not exceed 20 m the in situ measurements at lava edges are not representative of the total thickness and precise dem data are absolutely essential to calculate eruption volume based on lava thickness estimations this study is an example that demonstrates how insar will play a significant role in studying volcanoes in remote areas

the evolution of an asymmetric deltaic lobe sf gheorghe danube in association with cyclic development of the river mouth bar long term pattern and present adaptations to human induced sediment depletion abstract the asymmetric sf gheorghe lobe is the only active lobe in the danube delta associated with a river mouth bar and related barrier islands and spits that has continuously displayed cyclic development during the last 1500 years during the early cycles the sf gheorghe distributary experienced a significant increase in sediment load by an order of magnitude as a result of the successive avulsions occurred 1 5 1 2 ka which redistributed more water and sediment captured from the neighboring branches of impu ita southern distributary of the sulina arm and dunav morphological and sedimentological analyses together with a newly obtained chronology throw light on the multiple ridgeset 10 structure of sf gheorghe lobe each of them excepting the first one following a common evolutionary pattern reflected by the cyclic succession of the recurring stages i subaqueous mouth bar building ii barrier island emergence and iii transformation into a barrier spit with several secondary spits the spits become encased into the muddy deltaic plain as narrow sandy ridges building out on the downdrift side of the lobe as a barrier marsh plain whereas the updrift side constantly accreted fed by longshore currents forming a classic beach ridge plain the size of each ridgeset increased exponentially with every new cycle due to the constant lengthening of the coastline as the downdrift side of the lobe advanced seaward through a series of progressively larger similar quadrilaterals yielding a corresponding geometric progression of the delta front size even though each newly formed ridgeset cycle had a longer lifespan the latest cycles lasting 4 5 times longer than the first ones 200 440 years versus 50 80 years the evolutionary model remained unchanged as long as the balance between wave and river borne sediments defined by the sedimentary index si remained constantly low si 0 1 whereas the mean advance rates of the river mouth remained constant at c 10 m year abrupt changes occurred within the last cycle since the beginning of the 20th century as a consequence of human induced depletion of sediment supplied by the danube flow and is mainly expressed by the complete cessation of the updrift coastal progradation and the prevalence of erosion in front of the river mouth these changes which engendered a threefold increase of the si 0 37 at present are reflected by the recent 1930s present river mouth dynamics characterized by cessation of its long term seaward expansion in favor of downdrift migration this is indicative of the transition of the sf gheorghe mouth from an asymmetric to a deflected wave influenced delta morphology whose current developments mark a significant change in the multicentennial cyclic evolutionary pattern the asymmetric to deflected transition reflects the net increase in the influence of wave driven sediment circulation on river mouth morphology corresponding to a critical si threshold of ca 0 2 0 2 asymmetric 0 2 deflected

domains of spit evolution in the goro area po delta italy goro lagoon was formed during the 19th century in the southern part of the po delta its origin is related to the growth of a spit system which progressively occluded the southernmost interdistributary bay from the sea the development of the spits is due to the morphological prominence of the po delta which causes a divergent littoral drift enhanced by wave refraction over the delta front during the last century the spit was abandoned destroyed and re constructed several times because of the development of newer spits seawards using historical maps and aerial photographs three different periods are recognised featuring distinctive spit growth styles parallel fan shaped and branched the different domains of spit evolution are related to several factors mainly to the mutual influence of sediment discharge sand mining along the po river wave action over the delta front human induced subsidence and direct human interventions along the spits and for flood control

seismic stratigraphic analysis of the middle jurassic krossfjord and fensfjord formations troll oil and gas field northern north sea abstract the syn rift middle jurassic krossfjord and fensfjord formations troll field northern north sea contain a complex distribution of wave and tide dominated deltaic shoreline and shelf depositional environments of varying reservoir potential uncertainty exists in depositional models used to explain the spatial and temporal distribution of these depositional environments and the absence of coeval coastal plain deposits to date the proposed influence of growing rift related structures on stratigraphic architectures and sedimentation patterns in the units has been poorly defined in this study 3d seismic data are integrated with core biostratigraphic and wireline log data to produce a consistent geological interpretation for the formations seismic analysis has identified nine parasequences containing nne ssw striking delta scale clinoforms that prograded westwards over much of the field quantitative analysis highlights an increase in height and dip of clinoforms from proximal to distal locations coincident with an increase in grain size clinoform geometry is sigmoidal with well developed topsets that based on core data lack subaerial deposits these geometrical and sedimentological characteristics suggest that a subaqueous delta depositional system deposited the krossfjord and fensfjord formations in the troll field in the northeast of the field clinoforms exhibit highly variable strike and oblique cross sectional geometries which suggest that sediment was supplied from here and then redistributed through southward directed wave and longshore current activity rift related faulting is recognised to have occurred in the western part of the troll field only during deposition of the youngest fensfjord formation parasequence thus challenging the notion that these units are syn rift seismically imaged clinoforms in the under explored area south of the troll field prograded southward and are interpreted to represent coeval formation of a southward prograding spit that developed landward of the subaqueous delta platform present in the troll field the interpreted long lived subaqueous delta in the troll field constitutes a novel type of shallow marine reservoir

the transition from wave dominated estuary to wave dominated delta the late quaternary stratigraphic architecture of tiber river deltaic succession italy abstract this paper presents a detailed description of the stratigraphic architecture of the late pleistocene holocene tiber delta succession in order to document the passage from wave dominated estuary to wave dominated delta in the broader context of late quaternary sea level fluctuations this succession constitutes a sequence stratigraphic unit known as tiber depositional sequence tds which was deposited during the last glacial interglacial cycle last 120 ka our study is based on the examination of an enormous amount of data derived from the stratigraphy of about 300 wells petrographical and paleontological data foraminifera ostracoda pollen and plant macrofossils 14 c dating and from the integration of geomorphological and geoarcheological data recently a 100 m deep core pesce luna well was studied through a multidisciplinary approach and a detailed description of sedimentary facies foraminifer and ostracod assemblages pollen and 14 c dating is presented in this paper the new data allowed to produce three new correlation panels and to describe in more detail with respect to previous interpretations the stratigraphic depositional architecture of the tds which internally shows the preservation of sediment deposited during the early and late lowstand the transgressive and the highstand systems tracts alluvial and coastal depositional systems characterize the early lowstand phase of the tds which developed during the eustatic sea level fall between about 120 and 30 26 yr bp during the late lowstand phase which is characterized by stillstand and slow eustatic sea level rise a prograding delta and an aggrading incised valley fluvial fill developed the tiber incised valley was transformed into a wave dominated estuary during the transgressive phase tst whereas a coastal shelf sedimentation took place during the subsequent highstand phase hst this study confirms the lithofacies distribution resulting from transgression and infilling of the wave dominated estuaries but also shows how the transition to a wave dominated delta prograding at the time of sea level highstand occurred changes in sediment input climatic variations and more recently human activities played a major role in the development of the tiber delta during the last 20 000 yr bp in the last 3000 years a relationship between progradational phases of the delta and flood events of the tiber river has been highlighted suggesting also the formation and merging of barrier spits to the mainland

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

on the absence of insar detected volcano deformation spanning the 1995 1996 and 1999 eruptions of shishaldin volcano alaska shishaldin volcano a large frequently active basaltic andesite volcano located on unimak island in the aleutian arc of alaska had a minor eruption in 1995 1996 and a vei 3 sub plinian basaltic eruption in 1999 we used 21 synthetic aperture radar images acquired by ers 1 ers 2 jers 1 and radarsat 1 satellites to construct 12 coherent interferograms that span most of the 1993 2003 time interval all interferograms lack coherence within 5 km of the summit primarily due to persistent snow and ice cover on the edifice remarkably in the 5 15 km distance range where interferograms are coherent the insar images show no intrusion or withdrawal related deformation at shishaldin during this entire time period however several insar images do show deformation associated with a shallow ml 5 2 earthquake located 14 km west of shishaldin that occurred 6 weeks before the 1999 eruption we use a theoretical model to predict deformation magnitudes due to a volumetric expansion source having a volume equivalent to the 1999 erupted volume and find that deformation magnitudes for sources shallower than 10 km are within the expected detection capabilities for interferograms generated from c band ers 1 2 and radarsat 1 synthetic aperture radar images we also find that insar images cannot resolve relatively shallow deformation sources 1 2 km below sea level due to spatial gaps in the insar images caused by lost coherence the lack of any deformation particularly for the 1999 eruption leads us to speculate that magma feeding eruptions at the summit moves rapidly at least 80m day from n10 km depth and that the intrusion eruption cycle at shishaldin does not produce significant permanent deformation at the surface published by elsevier b v

wave influence in the construction shaping and destruction of river deltas a review abstract waves are an important agent in the construction shaping and destruction of river deltas notwithstanding the commonality of waves in oceans and seas wave influence on deltas varies considerably depending on the coastal morphology and nearshore bathymetry although there have been advances in understanding the way waves approaching a delta shape its shoreline much still remains to be known of the interactions between waves and river deltas deltas are built essentially from sediments supplied by rivers sand sized and coarser sediments may also be derived from nearby abandoned delta lobes or from older relict nearshore deposits transported by wave reworking and longshore currents alternatively delta erosion by waves can also release sediment that is redistributed alongshore or that accumulates offshore the extent to which bedload is supplied to and sequestered in or lost by deltas through waves and longshore transport strongly depends on interactions between waves and fluvial discharge at the river mouth these interactions and the mutual adjustments they engender are not only important in the overall balance between delta retreat progradation or aggradation but also in processes such as avulsion and channel switching as well as in the eventual survival of a delta in the face of sea level rise where waves are important fluvial liquid discharge is high and sediment supply is rich in bedload two important aspects are the blocking of waves and longshore currents by strong river discharge and the formation of bars at the river mouth field studies of the complex interactive processes prevailing where river flows encounter waves are however non existent and numerical modelling though promising hampered by scale constraints and the difficulty of replicating them and generating mouth bars in the presence of longshore currents this interaction influences the seaward extent of the delta mouth protuberance and its stability this protuberance then forming the regional shoreline template to which waves and longshore currents adjust longshore currents can redistribute wave reworked mouth bar deposits emplaced during strong river flow transport may be either divergent from the mouth or may be regionally unidirectional but wherein the symmetry of some deltas probably rare may be maintained by a strong river blocking effect on transport from the updrift flank the mouth protuberance may be such as to foster transport reversal counter drift at the delta margins that contributes to sediment sequestering within the delta these interactions largely contribute in shaping delta shorelines and together with the abundance of sediment supply and grain size determine the resultant wave formed shoreline barrier types which include spits more or less closely spaced beach ridges and barrier islands and cheniers in situations of punctuated progradation or retreat where several distributary mouths occur pronounced longshore variability in wave processes and wave induced sediment transport may ensue resulting in multiple drift cells that assure the retention of sand and coarse grained sediments within the delta waves can also be an important agent in the reworking and retreat of mud rich deltas that generally conform in morphology to the river dominated such as the mississippi or tide dominated such as the ganges brahmaputra or chao phraya types resulting in the episodic formation of sandy cheniers and beach ridges although sea level rise is likely to lead to enhanced wave reworking of deltas the possible prevalence of aggradation in lieu of progradation channel switching and avulsion and washover processes may contribute to the disorganization of waves and longshore transport fostering deltaic sequestering of sand and coarser sized sediment and delta survival the weakening of river discharges resulting from human activities will invariably lead however to enhanced wave reworking of deltas and to deltaic sediment redistribution by longshore currents the massive swing towards significant reductions in fluvial sediment supply today may signify the ultimate demise of many deltas in the coming decades through a process of delta shoreline straightening by waves in addition to accelerated sinking these various foregoing aspects of the relationship between waves and river deltas are reviewed here across a range of timescales and new interaction concepts proposed using numerous examples of deltas in the world and on the basis of case studies conceptual studies and numerical modelling studies in the literature spanning more than forty years

beach dune interactions on the dry temperate danube delta coast abstract beach dune seasonal elevation changes aeolian sand transport measurements bathymetric surveys and shoreline evolution assessments were used to investigate annual and seasonal patterns of dune development on sf ntu gheorghe beach the danube delta coast from 1997 to 2004 dune volume increased consistently 1 96 m 3 m 1 y 1 to 5 1 m 3 m 1 y 1 over this 7 year period with higher rates in the southward downdrift direction dune aggradation is periodically limited by storms each of which marks a new evolutionary phase of the beach dune system as a consequence of the variable beach morphology and vegetation density during a year foredune growth occurs during the april december interval while between december and april a slightly erosive tendency is present the pattern of erosion and deposition shown by the topographical surveys is in good agreement with the sand transport measurements and demonstrates the presence of a vigorous sand flux over the foredunes which is 20 50 smaller than on the beach this high sand flux due to low precipitation and sparse vegetation cover creates an aerodynamically efficient morphology on the seaward dune slope the seaward dune face accretes during low to medium onshore winds 5 5 12 m s 1 and erodes during high winds 12 m s 1

seasonal interannual and mesoscale variability of the black sea upper layer circulation derived from altimeter data 1 topex poseidon and ers altimeter data comprising the period from may 1992 to may 1999 are assimilated into a shallow water model for providing a dynamically consistent interpretation of the sea surface height variations and estimation of the temporal and spatial characteristics of the upper layer circulation in the black sea these 7 year long observations offer a new capability for interpretation of major transient and quasi permanent features of the upper layer circulation the instantaneous flow fields involve a complex eddy dominated system with different types of structural organizations in which the eddies and the gyres of the interior cyclonic cell interact continuously among themselves and with meanders and filaments of the rim current the circulation possesses a distinct seasonal cycle whose major characteristic features repeat every year with some year to year variability an organized two gyre winter circulation system disintegrates gradually into a series of interconnecting eddies in the summer and autumn months which are also characterized by more pronounced and complex mesoscale activity in the peripheral flow system our analyses suggest a revised schematic circulation picture of the major quasi permanent and recurrent elements of the black sea

unified view of sediment transport by currents and waves iv application of morphodynamic model the tr2004 transport formulations for clay silt and sand as proposed in parts 1 and 2 have been implemented in morphodynamic models to predict bed level changes these models have been verified using various laboratory and field data cases concerning coastal flow in offshore and near shore zones furthermore the model has been applied to two complicated sediment environments concerning the flow around a spurdike in a river and the tidal flow of cohesive sediments in the yangtze estuary in china overall it is concluded that the morphodynamic models using default settings performs reasonably well the applied scaling factors of the sediment transport model are in the generally accepted range of 0 5 2

process based modelling of a shoreface nourishment abstract a state of the art process based model is applied to hindcast the morphological development of a shoreface nourishment along the barrier island of terschelling the netherlands the applied morphodynamic model is delft3d for fully three dimensional flow and sediment transport in coastal environments owing to a complex geomorphological setting of the study area the curvi linear model includes adjacent tidal inlets and covers 40 70 km with an increasing grid size resolution towards the nourishment site in the center of the island in 1993 a total of 2 mm3 of sand was supplied to the nearshore bar zone off terschelling filling up the trough between the middle and outer bar by spring 1994 most of the nourished sediment had been redistributed onshore and welded onto the middle bar where it remained in the following years the morphodynamic model is applied to the prediction of this rapid nearshore profile behaviour the calibration of the model against an extensive set of full scale hydrodynamic data at several locations throughout the nearshore bar zone shows a good representation of the measured hydrodynamics morphodynamic results show a dependency on spatial scale on the scale of precise bed level evolution with respect to bar migration and growth model predictions are poor as the nearshore bars are predicted to flatten out resorting to bulk volumes integrated over larger spatial scales the model clearly has skill in predicting the overall effects of the nourishment the lack of phase shift between sediment transport and bathymetry is identified as the key controlling factor for the poor sandbar predictions

holocene sedimentation in the southwestern black sea interplay between riverine supply coastal eddies of the rim current surface and internal waves and saline underflow through the strait of bosphorus abstract an extensive grid of high resolution huntec deep tow seismic reflection profiles 9150 line km complemented by 72 gravity cores and 25 piston cores reveals that the sedimentary architecture of the southwestern black sea above a prominent shelf crossing unconformity is characterized by three allostratigraphic units allounits 1b 1c 1d separated by two regional unconformities and their correlative conformities 1 and 2 a fourth allounit 1a occurs as patchy remnants between the unconformity and a deeper pleistocene erosional unconformity 0 the chronology is established using 56 radiocarbon dates in five key piston cores the unconformity developed as a ravinement surface during the transgression associated with the transition from the last glacial maximum to holocene thus defines the base of the holocene successions allounit 1b is bounded at its base and top by the and 1 unconformities correlative conformities it was deposited between 12 5 and 7 4 cal ka and shows a notably patchy but widespread distribution across the southwestern shelf allounit 1c is bounded at its base and top by the 1 and 2 unconformities correlative conformities it was deposited between 7 4 and 5 3 cal ka allounit 1d accumulated above the 2 unconformity correlative conformity and was deposited since 5 3 cal ka interpretation of radiometrically dated cores and several detailed regional maps reveal that the widespread occurrence of 12 5 7 4 cal ka deposits allounit 1b across the middle and outer shelf provides no possibility for a holocene evaporative drawdown to a lowstand elevation of 120 m at 9 4 cal ka as suggested by yanchilina et al 2017 instead the volume of detritus in allounit 1b can only be explained if base level was sufficiently high to allow major distant rivers in bulgaria and romania e g kamchiya danube to contribute mud through long distance marine transport along a submerged shelf there is no evidence in any cores which sample allounit 1b that the sites were located in limans rather than on a transgressed shelf which had been flooded by post glacial meltwater and enhanced river runoff as the climate became more humid in the early holocene a prolonged stillstand at the spill depth controlled by the sill in the strait of bosphorus is confirmed by the elevation of a drowned recurved spit downdrift from cape emine bulgaria the development of the subaqueous unconformities correlative conformities 1 and 2 was facilitated by storm induced wave erosion transport bypass and erosion under the rim current and its anticyclonic eddies and possibly breaking internal waves volumetrics based on isopach maps and pre industrial sediment discharge rates of various rivers entering the western and southwestern black sea suggest that the total sediment yields of bulgarian and turkish rivers can only account for 13 14 of the total holocene succession allounits 1b 1d and that major input from the danube river via along shelf long distance transport must have occurred through the entire holocene

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

connecting large scale coastal behaviour with coastal management of the rhone delta abstract the aim of this paper is to connect the large scale coastal behaviour lscb of the rhone delta shoreface sediment budget river sediment input to the beaches climatic change with the impact and efficiency of hard engineering coastal structures the analysis of the 1895 to 1974 bathymetric maps as well as 2d modelling of the effect of wave blocking on longshore transport allows us to draw up a conceptual model of the lscb of the rhone delta the river sand input settled in the mouth area prodeltaic lobe favours the advance of adjacent beaches there is however a very weak alongshore sand feeding of the non adjacent beaches farther off the mouth after a mouth shift the prodelta is eroded by aggressive waves and the sand is moved alongshore to build spits this conceptual model suggests that there is a timeshift between the input of river sediments to the sea and the build up of a beach nonadjacent to the mouth nowadays as the river channels are controlled by dykes and human interventions a river shift is not possible it thus appears unlikely that the river sediments can supply the beaches of the rhone delta coast under these conditions we must expect that the problems of erosion will continue at saintes maries de la mer and on the faraman shore in areas with chronic erosion where the shoreline retreat has been partially stopped by hard engineering practices in the 1980s therefore these artificially stabilised sectors remain potentially under threat because of profile steepening and downdrift erosion evidenced in this paper by bathymetric profile measurements in the long term 1905 to 2003 the temporal analysis of the storm surges and the sea level show very weak but reliable increasing trends thus these climatic agents will be more aggressive on the beaches and on the coastal structures calling their efficiency into question we also evidence that the hard engineering structures were built in a favourable climatic context during the 1980s meanwhile the storm surges and the sea level rise are stronger since the 1990s regarding to the lscb of the rhone delta and the impact of hard engineering coastal structures we suggest that classical hard coastal protections are not the best option to protect the coast

elastic rebound following the kocaeli earthquake turkey recorded using synthetic aperture radar interferometry a basic model incorporating satellite synthetic aperture radar sar interferometry of the fault rupture zone that formed during the kocaeli earthquake of august 17 1999 documents the elastic rebound that resulted from the concomitant elastic strain release along the north anatolian fault for pure strike slip faults the elastic rebound function derived from sar interferometry is directly invertible from the distribution of elastic strain on the fault at criticality just before the critical shear stress was exceeded and the fault ruptured the kocaeli earthquake which was accompanied by as much as 5 m of surface displacement distributed strain 110 km around the fault prior to faulting although most of it was concentrated in a narrower and asymmetric 10 km wide zone on either side of the fault the use of sar interferometry to document the distribution of elastic strain at the critical condition for faulting is clearly a valuable tool both for scientific investigation and for the effective management of earthquake hazard

the topsar interferometric radar topographic mapping instrument the authors have augmented the nasa dc 8 airsar instrument with a pair of c band antennas displaced across track to form an interferometer sensitive to topographic variations of the earth s surface during the 1991 dc 8 flight campaign data were acquired over several sites in the us and europe and topographic maps were produced from several of these flight lines analysis of the results indicate that statistical errors are in the 2 4 m range while systematic effects due to aircraft motion are in the 10 20 m range the initial results from development of a second generation processor show that aircraft motion compensation algorithms reduce the systematic variations to 2 m while the statistical errors are reduced to 2 3 m

analysis of coseismic surface displacement gradients using radar interferometryc new insights into the landers earthquake the map of the coseismic displacement field generated by interferometric processing of synthetic aperture radar lsarr images taken before and after the june 28 1992 landers earthquake sequence brings new insights into the nature of deformation caused by these earthquakes we use the interferometric map generated by massonnet et al l1993r to analyze the surface displacement field in the vicinity of the fault trace complexities in the fringe pattern near the fault reflect shorthwavelength variations of the surface rupture and slip distribution and attest to large displacement gradients along two sections of the fault characteristic fringe patterns can be recognized contrasting in density and direction with patterns observed away from the rupture in order to understand the observed fringe patterns we compute synthetic interferograms in three simple cases l1r rigidhbody rotations about a vertical axis l2r about a horizontal axis ltiltr and l3r distributed simple shear the orientation and spatial separation of interferometric fringes predicted by these models help constrain nearhfield deformation and rupture parameters where the kickapoo fault connects with the homestead valley fault the interferogram shows a clear pattern of parallel n20 w fringes separated by about 160 m this pattern and vertical offsets measured along the kickapoo fault suggest that the block between this fault and the johnson valley fault may have been tilted down to the west a 5hkm block lifted by l m on one side would be tilted by an angle of 0 01 l190 radr producing fringes separated by about 160 m parallel to the tilt axis such a tilt parallel to a n20 w direction would account for the gradual northward increase of the vertical slip component observed along the kickapoo fault this tilt may also explain the 1 m of reverse slip observed along the slip gap section of the homestead valley break between the southern end of the johnson valley fault and the eureka peak fault where no surface rupture has been mapped the dense pattern of fringes implies distributed shear probably resulting from fault slip at depth the density and direction of the fringes in the gap are consistent with a righthlateral slip of 1 2 3 8 m on a blind fault locked above the depth of 1 5 2 km such observations of small wavelength features in the sar interferogram bring new insights into the nearhfield displacement gradient and thus on response of the uppermost crust to seismic rupture

transgressive depositional systems of the mississippi delta plain a model for barrier shoreline and shelf sand development abstract depositional sequences generated in the mississippi river delta plain consist of a regressive and a transgressive component the transgressive component has been considerably less studied but accounts for the majority of the surface area on the lower mississippi river delta plain and up to 50 percent of the total sequence thickness in shallow water deltas the development and preservation of transgressive depositional systems in abandoned delta complexes follows the process of transgressive submergence in which the horizontal component of reworking occurs during shoreface retreat combined with a vertical component of submergence acting to preserve the sequence the evolution of transgressive depositional systems in each of the abandoned holocene mississippi river delta complex s can be summarized in a three stage model beginning with stage 1 an erosional headland and flanking barriers in this stage regressive sand deposits contained within abandoned deltaic headlands are reworked by the eroding shoreface and dispersed longshore into contiguous flanking barriers enclosing restricted interdistributary bays submergence of the delta plain during relative sea level rise generates an intradeltaic lagoon separating the former stage 1 sand body from the shoreline forming stage 2 a transgressive barrier island arc the landward migrating barrier island arc is unable to keep pace with relative sea level rise and the retreating mainland shoreline resulting in submergence and the formation of stage 3 an inner shelf shoal following submergence the former barrier island arc sand body continues to be reworked into a marine sand body on the inner continental shelf during stage 3 this sequence of coastal evolution provides direct evidence of barrier island formation with each stage producing a distinctive stratigraphic signature the current sea level rise models of shoreface retreat and in place drowning developed for the u s atlantic continental shelf do not adequately explain either the morphology or the stratigraphy of transgressive mississippi river delta sand bodies current models of mississippi deltaic stratigraphy emphasize the deep water artificially maintained balize delta which differs considerably from the shallow water shelf phase delta complexes that are the primary depositional constituents of he holocene mississippi river delta plain

ground deformation associated with the march 1996 earthquake swarm at akutan volcano alaska revealed by satellite radar interferometry in march 1996 an intense swarm of volcano tectonic earthquakes 3000 felt by local residents mmax 5 1 cumulative moment of 2 7 1018 n m beneath akutan island in the aleutian volcanic arc alaska produced extensive ground cracks but no eruption of akutan volcano synthetic aperture radar interferograms that span the time of the swarm reveal complex island wide deformation the western part of the island including akutan volcano moved upward while the eastern part moved downward the axis of the deformation approximately aligns with new ground cracks on the western part of the island and with holocene normal faults that were reactivated during the swarm on the eastern part of the island the axis is also roughly parallel to the direction of greatest compressional stress in the region no ground movements greater than 2 83 cm were observed outside the volcano s summit caldera for periods of 4 years before or 2 years after the swarm we modeled the deformation primarily as the emplacement of a shallow east west trending north dipping dike plus inflation of a deep mogi type magma body beneath the volcano the pattern of subsidence on the eastern part of the island is poorly constrained it might have been produced by extensional tectonic strain that both reactivated preexisting faults on the eastern part of the island and facilitated magma movement beneath the western part alternatively magma intrusion beneath the volcano might have been the cause of extension and subsidence in the eastern part of the island we attribute localized subsidence in an area of active fumaroles within the akutan caldera by as much as 10 cm during 1992 1993 and 1996 1998 to fluid withdrawal or depressurization of the shallow hydrothermal system

medium term coastal response at the ebro delta spain abstract measurements of shoreline displacements along the ebro delta coast have been used to estimate the medium term evolution of the coastline aerial photographs and beach profile surveys covering the last 35 years have been used shoreline data obtained from beach surveys have been analysed using a linear regression technique in order to filter out short term components the medium term scale has been derived from the asymptotic trend with this filtered analysis results have been compared with trends observed in the past and a similar qualitative behaviour has been found rates of change have decreased because the shoreline has slowly evolved towards a more stable configuration a profile closure depth of 7 m has been estimated based on morphological changes in the submerged profiles and then used to convert shoreline displacements into yolume changes from these a medium term sediment budget has been calculated based on the available evidence it has been assumed that these changes are mainly due to wave induced longshore transport gradients assuming proper boundary conditions the net longshore transport scheme has been estimated for each hemidelta the results obtained using this method are in good agreement with the longshore transport rates predicted by well known transport formulae