photometric changes on saturn s titan evidence for active cryovolcanism 1 we report infrared spectrophotometric variability on the surface of saturn s moon titan detected in images returned by the visual and infrared mapping spectrometer vims onboard the cassini saturn orbiter the changes were observed at 7 s 138 w and occurred between october 27 2005 and january 15 2006 after that date the surface was unchanged until the most recent observation march 18 2006 we previously reported spectrophotometric variability at another location 26 s 78 w cassini synthetic aperture radar sar images find that the surface morphology at both locations is consistent with surface flows possibly resulting from cryovolcanic activity wall et al companion paper this issue the vims reported time variability and sar morphology results suggest that titan currently exhibits intermittent surface changes consistent with present ongoing surface processes we suggest that these processes involve material from titan s interior being extruded or effused and deposited on the surface as might be expected from cryovolcanism

steep sided domes on venus characteristics geologic setting and eruption conditions from magellan data a survey of more than 95 percent of the venus surface reveals 145 steep sided domes which can be subdivided into a variety of morphologic forms the most common being shaped like inverted bowls or flat topped domes results of a preliminary analysis of the distribution and geologic setting of the domes are presented the relation of the domes to analogous terrestrial features is examined and possible models for their mode of emplacement are outlined

shapes of venusian pancake domes imply episodic emplacement and silicic composition the main evidence available for constraining the composition of the large circular pancake domes on venus is their gross morphology laboratory simulations using polyethylene glycol show that the height to diameter aspect ratios of domes of a given total volume depend critically on whether their extrusion was continuous or episodic with more episodes leading to greater cooling and taller domes thus without observations of their emplacement the compositions of venusian domes cannot be uniquely constrained by their morphology however by considering a population of 51 venusian domes to represent a sampling of many stages during the growth of domes with comparable histories and by plotting aspect ratio versus total volume we find that the shapes of the domes are most consistent with episodic emplacement on earth this mode of dome growth is found almost exclusively in lavas of dacite to rhyolite composition strengthening earlier inferences about the presence of evolved magmas on venus

soil geomorphology identifying relations between the scale of spatial variation and soil processes using the variogram practitioners of geostatistics often fail to make associations between the patterns of variation on their maps of kriged predictions and the physical processes that might generate them geostatistical approaches that use knowledge of the underlying process have been proposed to reduce the number of soil samples required also if the scale of variation identified by the variogram can be linked to process it could be incorporated as a scale factor into existing deterministic models to attempt to relate the scale and pattern of variation in topsoil properties to processes the topsoil of four field sites in southern england on different parent materials and with a variety of topography was sampled relations between variogram range topography and parent material were examined the variogram ranges for parent materials that result in heavier soil textures tended to be longer as were those for plateau and valley areas compared with slopes possible links between these patterns and soil processes were investigated by examining 1 changes in soil characteristics with depth 2 moving correlations 3 variation in soil properties with topography within fields 4 directional variograms and 5 derived topographic attributes the predominance of vertical rather than lateral movements of water through the soil in plateau and valley positions was identified as responsible for the longer range of variograms in these locations hydraulic conductivity was suggested as a possible underlying cause of differences in the scale of variation in the topsoil between parent materials

field observations on the morphodynamic evolution of a low energy rip current system abstract a field experiment was conducted at palm beach nsw australia to investigate morphodynamic relationships operating within a rip current system during a near complete sequence of beach state evolution under decreasing energy conditions observations and measurements were obtained from nearshore surveys multiple dye releases oblique photographs and the deployment of various combinations of nine ducted impellor flow meters and five pressure sensors over a seven day period in rip and feeder channels the dataset provides a unique opportunity to assess and quantify aspects of the accretionary model of wright and short mar geol 56 1984 93 118 for intermediate beaches the morphology of the main rip channel exhibited distinct sequential adjustments with a narrowing of channel width an increase in channel depth a reduction in the cross sectional area available for rip flow and an increase in morphological relief rip flow velocity increased during the observed evolution and was also modulated by the tide experiencing maximums at low tide and minimums at high tide morphologic and kinematic adjustments of the rip system were most pronounced during the transition to a transverse bar and rip state the existence of a dominant feeder in a twin feeder and rip system contributed to the migration and establishment of a rip head over the seaward slope of the opposite longshore bar net erosion in the rip channel was balanced by net deposition in the feeder channels and bar crests and qualitative observations suggest that this rip head bar both receives transported sediments from the rip channel and contributes sediments to the ongoing accretion of the beach system a direct relationship was found to exist between rip morphology and flow with rip velocity increasing as cross sectional rip channel area decreases and these results are incorporated in a conceptual modification of the model of wright and short the results of this study are restricted to a subset of commonly occurring beaches but show that accretionary beach state evolution on intermediate beaches is indeed characterised by an increase in rip current velocity the nature of which can be linked to morphologic control in addition the rip head bar is identified as a potentially key component of low energy rip system evolution

stress strain time numerical modelling of a deep seated gravitational slope deformation preliminary results abstract an analysis of the effects of creep on the development of a deep seated gravitational slope deformation dsgsd carried out by numerical modelling is described the slope rock mass evolution has been simulated applying different creep rheological models the studied dsgsd is located in the central italian alps val s giacomo it is characterised by three main scarps different sets of tensile trenches and counterscarps mapped during a detailed geomorphological survey the mechanical behaviour of the rock masses in terms of elasto plastic parameters has been defined on the base of laboratory and in situ tests in order to simulate this instability process a stress strain time numerical modelling has been performed by a finite difference numerical code fast lagrangian analysis of continua flac the effects of different constitutive model laws have been considered the visco elastic maxwell model the visco elastic burger model and the elasto visco plastic burger model the modelling has been performed simulating the melting of the ancient glacier starting from its maximum load because of the difficulty to determine rock mass creep parameters for each of the rheological models a sensitivity analysis has been performed varying the physical mechanical properties the visco elasto plastic model allows to underline the formation of shear surface showing a depth and a shape in good agreement with the morphologic features of the slope the only action of unloading due to glacier melting seems to be insufficient to generate deep critical surfaces which can be related with the formation of the dsgsd

forecasting giant catastrophic slope collapse lessons from vajont northern italy rapid giant landslides or sturzstroms are among the most powerful natural hazards on earth they have minimum volumes of similar to10 6 10 7 m 3 and normally preceded by prolonged intervals of accelerating creep are produced by catastrophic and deep seated slope collapse loads similar to1 10 mpa conventional analyses attribute rapid collapse to unusual mechanisms such as the vaporization of ground water during sliding here catastrophic collapse is related to self accelerating rock fracture common in crustal rocks at loads similar to1 10 mpa and readily catalysed by circulating fluids fracturing produces an abrupt drop in resisting stress measured stress drops in crustal rock account for minimum sturzstrom volumes and rapid collapse accelerations fracturing also provides a physical basis for quantitatively forecasting catastrophic slope failure c 2003 elsevier science b v all rights reserved

dynamics of a high energy dissipative surf zone vright l d guza r t and short a d 1982 dynamics of a high energy dissipative surf zone mar geol 45 41 62 pressure and horizontal current u v time series were measured at different positions across the inner 150 m of a wide 500 m surf zone of a microtidal high wave energy beach incident waves had average heights of 3 4 m with maxima of 5 m and periods of 12 to 15 sec bores of broken waves diminished in height at a nearly constant rate as they progressed across the surf zone the ratio of bore height h to local water depth h was everywhere less than 1 for even the highest bores and was on the order of 0 40 for the significant bores at incident wave frequencies rip circulation was weak or absent but a moderate longshore current was present shore normal flows were vertically segregated with strong net onshore flows prevailing just below the surface accompanied by weaker net seaward flows near the bed spectra of water surface oscillations as determined from pressure u and v reveal that most of the energy in the inner surf zone was at infragravity frequencies periods greater than 30 sec shoreward decay of wave energy at incident wave frequencies was accompanied by shoreward growth of infragravity energy near the beach the infragravity oscillations had heights on the order of 1 m cross spectra show that the infragravity oscillations were standing in the shore normal direction from the relative magnitudes of infragravity versus incident wave currents it is inferred that the surf beat may be an order of magnitude more important than incident waves to the transport of sediment in the inner surf zone

cassini radar views the surface of titan the cassini titan radar mapper imaged about 1 of titan s surface at a resolution of 0 5 kilometer and larger areas of the globe in lower resolution modes the images reveal a complex surface with areas of low relief and a variety of geologic features suggestive of dome like volcanic constructs flows and sinuous channels the surface appears to be young with few impact craters scattering and dielectric properties are consistent with porous ice or organics dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons

geomorphologic mapping of the menrva region of titan using cassini radar data abstract we made a detailed geomorphologic map of the menrva region of titan using cassini radar data as our map base using similar techniques and approaches that were applied to mapping magellan radar images of venus and earlier more generalized titan maps we were able to define and characterize 10 radar morphologic units along with inferred dunes and fluvial channels from the radar data structural features such as scarps ridges and lineaments were also identified using principles of superposition cross cutting and embayment relations we created a sequence of map units for this region we interpret menrva to be a 440 km wide degraded impact basin in agreement with earlier studies by elachi et al elachi c et al 2006 nature 441 709 713 and wood et al wood c a lorenz r kirk r lopes r mitchell k stofan e and the cassini radar team 2010 icarus 206 334 344 and identify it as the oldest feature in the map region exogenic processes including hydrocarbon fluid channelization forming the elivagar flumina channel network and dune fields resulting from aeolian activity are the current geologic processes dominating our map area and these processes have contributed to the erosion of the crater s ejecta field there is evidence of multiple episodes of channel formation erosion and burial by aeolian deposits as observed elsewhere on titan by e g barnes et al barnes j w et al 2005 icarus 195 400 414 channel outflow regions have morphologies suggestive of streams formed by flash floods and dune fields are small and restricted rather than forming large dune seas consistent with a desert like environment for this region with low supply of hydrocarbon particles also consistent with other studies by e g lorenz et al lorenz r d et al 2008a planet space sci 56 1132 1144 there is no evidence of cryovolcanism or non impact related tectonic activity in the menrva region although this region is too small to infer anything about the roles of these processes elsewhere on titan this work suggests detailed geomorphologic mapping can confidently be applied to cassini radar data and we suggest that more extensive mapping should be done using radar iss and vims data geographically distributed across titan to assess its usefulness for a future combined radar iss vims based global geologic map

footwall slope stability analysis with the numerical manifold method abstract this paper extends the numerical manifold method nmm for footwall slope stability analysis a fracturing algorithm based on the mohr coulomb criterion with a tensile cutoff is implemented into the nmm code the developed program is first calibrated by simulating four typical crack problems it is then applied to analyze the potential footwall slope instability parametric studies with respect to dip of a bedding plane orientation of a predominant joint set the bedding profile etc are carried out numerical results indicate that the developed program can simulate the opening and sliding along pre existing discontinuities fracturing through intact rock as well as kinematics of the failed slope and can also reproduce the major failure mechanisms observed in footwall slope collapses the nmm is promising for such problems and deserves to be further developed to be practically used in natural excavated rock slope stability analysis and open pit slope design

influence of large scale topography on gravitational rock mass movements new insights from physical modeling 1 gravitational slope failures and associated rock mass movements can be observed at various scales in the same area it seems obvious that the different movement scales should be interrelated but their relationships are poorly understood we address this problem using 3 d physical modeling experiments were conducted with mechanically homogeneous models with two scale topographic features a large scale corresponds to the whole mountain several kilometers and a smaller one to a part of a mountain slope one kilometer results show that large scale relief induces large scale large volume gravitational movements introduction of small scale topographic features results not only in the generation of smaller scale landslides but also in considerable changes in the deformation pattern the various scale processes occur simultaneously and affect each other to predict the evolution of a landslide it is therefore necessary to take into account the topography and deformation pattern at various scales

vertical and horizontal structure in cross shore flows an example of undertow and wave set up on a barred beach greenwood b and osborne p d 1990 vertical and horizontal structure in cross shore flows an example of undertow and wave set up on a barred beach coastal eng 14 543 580 eulerian measurements of the horizontal cross shore velocity field in the lowermost meter of the water column in association with measurements of waves and the mean elevation of the water surface across a nontidal low relief barred surf zone reveal a spatially coherent patterns of the timeaveraged first second and third moments of the velocity field which vary temporally in direct response to the incident waves b large asymmetries in the flow field with offshore directed mean flows upto 0 20 m s a and onshore directed velocity skewness the third moment normalized by the standard deviation upto 0 60 c mean flows decrease and oscillatory flows measured by the standard deviation of the velocity field increase towards the water surface d a fourth order polynomial provides the best fit to the cross shore set up reflecting the influence of variable energy dissipation due to topographic controls on wave breaking e significant linear correlations exist between the cross shore mean velocities and the maximum set up of the still water surface near to the shoreline upto 82 of the observed variability in the former can be accounted for by linear regressions f set up is highly correlated with the incident wave height 86 of the observed variability in the former can be accounted for by a linear regression g gradients in the mean water surface are significantly less than those predicted by a linear function of beach slope as originally proposed by bowen et al even using an appropriate breaking criterion 0 4 0 6 for the spilling breakers recorded cross shore circulation over the low relief barred nearshore slope is predominantly two dimensional over the outer bar in this case study the near bed mean flow is an undertow responding to the balance between the wave generated depth dependent momentum flux directed onshore the stress induced by the onshore mass transport under waves and wind and the hydraulic pressure gradient induced by set up of the mean water level

modelling of possible mud volcanism on titan possible sedimentary basins on titan are potential sites for the formation of mud volcanoes in order to constrain the appearance of such features in remotely sensed imagery being acquired by the cassini spacecraft we have modelled the formation of mud volcanoes on titan for a series of plausible mud compositions climatic conditions and geological settings as well as addressing the full range of eruption variables mud viscosity conduit diameter and eruption duration we find that for an acetylene mud source containing 20 wt liquid methane in pore spaces overlain by a sheet of water ice 500 m thick a mud volcano can grow as high as 140 m assuming reasonable eruption parameters such an edifice may develop into a pancake like dome several kilometres in diameter if observed and properly characterised mud volcanoes would provide an important window on the subsurface distribution and dynamics of solids and liquids in sedimentary basins on titan

geomorphological map of the afekan crater region titan terrain relationships in the equatorial and mid latitude regions we carried out geomorphological mapping in a mid latitude area surrounding the afekan crater region on titan we used cassini radar synthetic aperture radar mode data as the basemap supplemented by cassini radar microwave emissivity imaging science subsystem iss infrared data visual and infrared mapping spectrometer vims spectral images and topography derived from synthetic aperture radar sar mapping was done at a spatial scale of 300 m pixel which corresponds to a map scale of 1 800 000 we describe multiple terrain units and their spatial relations we describe five broad classes of units that are in agreement with previous mapping efforts crater labyrinth hummocky mountainous plains and dune terrain classes we subdivide these into seven crater units four hummocky mountainous units six plains units and three dunes units our results show that plains are the dominant unit in titan s mid latitudes of the plains units the undifferentiated plains are the largest by total areal extent in the mapped region accounting for over 45 of the mapped area we developed a stratigraphic sequence that has the hummocky mountainous and labyrinth terrains as the oldest units the observed properties of the hummocky mountainous terrain are consistent with fractured water ice materials while the labyrinth terrains are consistent with organic materials the youngest units are the dune units and streak like plains units with the undifferentiated plains units being of intermediate age the microwave emissivity of the undifferentiated plains and dune units are consistent with organic materials given their properties and stratigraphic placement we conclude that the hummocky mountainous terrains are most consistent with the presumed crustal materials of titan the plains materials are consistent with deposits resulting from the transport and emplacement of organic rich materials predominantly by aeolian mechanisms our geomorphological mapping results are consistent with the equatorial and mid latitudes of titan being dominated by organic materials that have been deposited and emplaced by aeolian activity

the vanishing cryovolcanoes of ceres ahuna mons is a 4 km tall mountain on ceres interpreted as a geologically young cryovolcanic dome other possible cryovolcanic features are more ambiguous implying that cryovolcanism is only a recent phenomenon or that other cryovolcanic structures have been modified beyond easy identification we test the hypothesis that cerean cryovolcanic domes viscously relax precluding ancient domes from recognition we use numerical models to predict flow velocities of ahuna mons to be 10 500 m myr depending upon assumptions about ice content rheology grain size and thermal parameters slower flow rates in this range are sufficiently fast to induce extensive relaxation of cryovolcanic structures over 108 109 years but gradual enough for ahuna mons to remain identifiable today positive topographic features including a tholus underlying ahuna mons may represent relaxed cryovolcanic structures a composition for ahuna mons of 40 ice explains the observed distribution of cryovolcanic structures because viscous relaxation renders old cryovolcanoes unrecognizable

flow characteristics along the rip current system under low energy conditions abstract this paper aims to determine the flow signature of the rip current under low energy conditions based on current meters at herzliyya beach israel on the southeastern mediterranean shore field experiments conducted under relatively calm wave conditions t sig 3 6 s h sig 0 3 1 1 m included current and wave monitoring with morphological mapping current data were analysed for shore normal and resultant components and the time series of instantaneous and smoothed velocities provided current and orbital wave velocities statistical and spectral processing yielded energy distributions specific current discharge and directional data velocity and velocity time asymmetry increased from the feeders to the neck and subsequently slowed down towards the rip head the directional range of the flow was narrow in channeled feeders and even better concentrated at narrow necks with higher velocities the flows at the rip head were typically divergent systematic spatial change of energy spectra was observed along the rip system the subharmonic frequency band dominated the feeders and the inner surf embayments and decreased gradually toward the rip neck with a simultaneous gradual increase in incident wave frequency the infragravity band frequency was minor everywhere velocity spectra at oblique bars with sheltered areas differed from spectral changes at transverse bars with an exposed inshore the velocity at the rip neck was above the threshold for grain movement whereas at the head it was usually below the threshold textural parameters of the beach sand could not be systematically related to the current velocity i e no environmental groupiness was evident along the rip system

the lobes of lava flows on earth and olympus mons mars the lobate distal margins of lava flows provide a useful source of morphological information on the rheology of the lava if the lobes are assumed to represent the arrest of free flowing isothermal bingham fluids on a slope the widths of lobes are a more useful practical index than lobe thicknesses because they are about an order of magnitude larger and can be more accurately measured from aerial photographs and other remote images lobes do not suffer from the changes in morphology that channels undergo during the course of eruptions a terrestrial data set of flow lobe and ancillary measurements from lavas throughout the range alkali olivine basalt to rhyolite shows some features that are predicted by the isothermal bingham fluid model these are correlation of width and thickness over more than two orders of magnitude and essentially no correlation of aspect ratio with slope there is a positive correlation of lobe width with silica content of the lava from a data set of measurements on lava flow lobes from the martian volcano olympus mons the mean value of aspect ratio 0 07 was found to be significantly less than that for the terrestrial data set 0 19 higher general levels of effusion rate on olympus mons are probably the factor responsible after normalisation lobe widths on olympus mons are found to be largely equivalent to those expected for terrestrial flows with andesitic basaltic silica contents

scale issues in weathering studies a review of the major scale issues in weathering studies reveals concerns over the fundamental spatio temporal distributions of weathering phenomena as well as issues of upscaling microscope based observations and linking different scales of observations in explanations of landform development various strategies are proposed which can be used to tackle these issues many rooted in non linear dynamical systems ideas as an initial step spatio temporal scale distributions are estimated here for weathering processes landforms and controls based on a range of empirical data two case studies of phytokarst in grand cayman and blistering and scaling of building stones are presented to illustrate the types of data that might be used to establish more convincing scale linkages in weathering investigations

the nature and origin of charon s smooth plains charon displays extensive plains that cover the equatorial area and south to the terminator on the sub pluto hemisphere observed by new horizons we hypothesize that these plains are a result of charon s global extension and early subsurface ocean yielding a large cryoflow that completely resurfaced this area leaving the plains and other features that we observe today the cryoflow consisted of ammonia rich material and could have resurfaced this area either by cryovolcanic effusion similar to lunar maria emplacement or a mechanism similar to magmatic stoping where lithospheric blocks foundered geological observations modeling of possible flow rheology and an analysis of rille orientations support these hypotheses

spatial patterns of scale effect on specific sediment yield in the yangtze river basin abstract this paper examines the spatial variation of sediment yield in the yangtze basin in china a large basin with complex geology climate land use history and extensive sediment monitoring 287 stations with drainage area less than 10 000 km2 were used to study the scale effects of sediment yield in order to develop scale relations for regional sediment yield the whole study area was divided into eight sub basins relation between specific sediment yield and drainage basin area was built for each sub basin regional scaling relation was analyzed based on landforms geology lithology and land use of each sub basin three regional trends were identified in relation to the drainage area 1 a declining trend due to soil erosion on heavily cultivated steep land and the storage of sediment in floodplains 2 a flat trend due to mass movement on the upper reach and heavy agricultural disturbance on the middle and lower reaches and 3 an increasing trend due to downstream recruitment of sediment from land downstream where slope farming and deforestation occurred using these developed relations areally adjusted sediment yield maps were created over the entire yangtze basin

on convection in ice i shells of outer solar system bodies with detailed application to callisto it has been argued that the dominant non newtonian creep mechanisms of water ice make the ice shell above callisto s ocean and by inference all radiogenically heated ice i shells in the outer solar system stable against solid state convective overturn conductive heat transport and internal melting oceans are therefore predicted to be or have been widespread among midsize and larger icy satellites and kuiper belt objects alternatively at low stresses where non newtonian viscosities can be arbitrarily large convective instabilities may arise in the diffusional creep regime for arbitrarily small temperature perturbations for callisto ice viscosities are low enough that convection is expected over most of geologic time above the internal liquid layer for plausible ice grain sizes a few mm the alternative for early callisto a conducting shell over a very deep ocean 450 km is not compatible with callisto s present partially differentiated state moreover if convection is occurring today the stagnant lid would be quite thick 100 km and compatible with the lack of active geology nevertheless callisto s steady state heat flow may have fallen below the convective minimum for its ice i shell late in solar system history in this case convection ends the ice shell melts back at its base and the internal ocean widens considerably the presence of such an ocean of order 200 km thick is compatible with callisto s moment of inertia but its formation would have caused an 0 25 radial expansion the tectonic effects of such a late slow expansion are not observed so convection likely persists in callisto possibly subcritically ganymede due to its greater size rock fraction and full differentiation has a substantially higher heat flow than callisto and has not reached this tectonic end state titan if differentiated and triton should be more similar to ganymede in this regard pluto like callisto may be near the tipping point for convective shutdown but uncertainties in its size and rock fraction prevent a more definitive assessment

the longshore flow component in low energy rip channels the mediterranean israel abstract we examined in the field the near bed longshore v flow component in rip channels at the herzliyya beach israel on the southeastern mediterranean field experiments conducted under relatively calm wave conditions t sig 3 6 s h sig 0 3 1 1 m included current and wave monitoring and morphological mapping time series of instantaneous and smoothed shore parallel current velocities and of the orbital components were analysed including statistical and spectral processing the peak instantaneous velocities of waves and currents combined were in excess of the threshold motion of the local sand taken as 0 3 m s some velocities even exceeded the threshold for sheet flow transport 0 9 m s the feeder and the neck demonstrated the highest longshore flow components whereas the rip head typically showed the lowest longshore velocities the unsteadiness of the net longshore current was very high feeders typically showed a mean unidirectional longshore current however directional fluctuations gradually increased towards the rip head the data suggest a clear spectral structure most energy 46 67 was in the gravity range with 13 35 subharmonic and minor 13 16 in the infragravity band systematic cross shore spatial trends of the energy spectra components were linked to bar morphology and to exposure to incident waves

europa tidal heating of upwelling thermal plumes and the origin of lenticulae and chaos melting europa we show that tidal energy can be preferentially focused in rising plumes for viscosities in agreement with laboratory experiments when the plume cores reach the base of the outer cold brittle layer they spread laterally causing shallow melting disruption and formation of terrain similar to lenticulae and chaos we show that this mechanism can readily explain the major characteristics of chaos and lenticulae even if the average outer solid ice layer thickness is larger than 20 km

forecasting hazard scenarios and implications for the evaluation of countermeasure efficiency for large debris avalanches abstract the key objective of a slope failure study is to reduce deaths injuries and property damage predictions of slope failures are mandatory to reduce hazard and vulnerability of elements at risk with appropriate warning policy and properly designed countermeasures numerical modelling has been recently used as an approach to back analyse real events but few attempts have been carried out to forecast potential failure scenarios recently a debris avalanche involving about 1 2 million m 3 of debris and a nearby debris slide flow with failure volume of 0 1 million m 3 occurred in the italian prealps from the accumulation of a paleo landslide field surveys and monitoring revealed that the upper part of the slope above the largest recent landslide is unstable with a possible failure volume between 1 and 1 5 million m 3 we conducted comprehensive fieldwork and analyses including geological and geomorphological surveys compilation of a landslide inventory map collection of rainfall records study of triggering mechanisms and geotechnical properties of the failed materials slope stability analyses and back analyses of the runout phase of the landslide events through a series of slope stability analyses the possible failure volume sliding surface and topography are estimated consistent with field monitoring data furthermore with the help of calibration through back analyses of the past landslide events we assign a given degree of danger to slope elements with analogous conditions we then numerically predict the runout patterns and mobility of the potential instabilities the effectiveness of the planned passive countermeasures for potential zoning management is evaluated

cryomagmatic mechanisms for the formation of rhadamanthys linea triple band margins and other low albedo features on europa we investigate cryomagmatic mechanisms for the formation of the diffuse low albedo margins of triple bands and haloes associated with elliptical lenticulae on europa one mechanism involves explosive venting of a gas particle spray derived from a subsurface body of volatile bearing water assuming the dark features represent cryoclastic deposits erupted from a medial or central vent modeling the dynamics of the eruptive plumes indicates that eruption velocities of 30 to 250 m s 1 and volatile contents of 0 1 to 20 wt are required to produce deposits having the observed dimensions calculated heights for ballistic plumes range from 1 to 25 km as an alternative mechanism we consider conductive heating of lithospheric ice by a subsurface heat source e g a warm ice diapir or cryomagmatic intrusion which promotes enhanced sublimation of surface ice producing local enrichment of nonice material an analytical model describing a constant temperature infinite heat source places lower bounds on the time scales required to produce a detectable feature a numerical treatment of more realistic geometries and boundary conditions allows cooling of the heat source to be modeled we find that the thermal model satisfactorily explains features with the dimensions of minor lineaments and lenticulae haloes a few kilometers over time intervals of 104 to 105 years the formation of a sublimation lag deposit proceeds rapidly once the ice temperature exceeds a threshold of 130 k however for triple bands measuring up to 25 km in width additional heat sources such as repeated or multiple intrusions are necessary to reproduce the observed dimensions this is consistent with the observation that well developed triple bands typically have multiple medial ridge sets each of which may represent a discrete tabular heat source although neither the volcanic nor intrusive thermal model can be ruled out at this stage the latter is a more satisfactory explanation for some characteristics of the low albedo features analyzed in this study

the unique radar properties of silicic lava domes 1 silicic lava domes exhibit distinct morphologic characteristics at scales of centimeters to kilometers multiparameter radar observations capture the unique geometric signatures of silicic domes in a set of radar scattering properties that are unlike any other natural geologic surfaces backscatter cross section values are among the highest observed on terrestrial lava flows and show only a weak decrease with incidence angle cross polarization backscatter hv shows a unique behavior increasing with increasing wavelength circular polarization ratios are relatively high in the 0 3 0 95 range and increase with increasing wavelength field measurements of boulder size frequency distributions and microtopography indicate that silicic dome surfaces are among the roughest ever measured rms heights at a 1 m lateral scale range from 13 cm to 50 cm rms slopes at 1 m spacing range from 12 to 43 degrees modeling of the scattering behavior suggests it results from a combination of rough surface facet scattering and scattering from block edges that act as a random collection of dipoles the unusual wavelength dependence of the radar parameters appears to result from a higher component of edge scattering at large wavelengths producing for example higher cross polarized backscatter at p band 68 cm steep sided volcanic domes on venus superficially resemble terrestrial silicic domes in plan view gross morphology but few similarities remain when the radar scattering and three dimensional shapes of the features are compared the unique radar scattering properties suggest that such volcanic surfaces can be identified with multiparameter radar observations in future planetary radar missions and in active terrestrial volcanoes where dome development can represent serious hazards

the geology of hotei regio titan correlation of cassini vims and radar abstract joint cassini vims and radar sar data of 700 km wide hotei regio reveal a rich collection of geological features that correlate between the two sets of images the degree of correlation is greater than anywhere else seen on titan central to hotei regio is a basin filled with cryovolcanic flows that are anomalously bright in vims data in particular at 5 m and quite variable in roughness in sar the edges of the flows are dark in sar data and appear to overrun a vims bright substrate sar stereo topography shows the flows to be viscous 100 200 m thick on its southern edge the basin is ringed by higher 1 km mountainous terrain the mountains show mixed texture in sar data some regions are extremely rough exhibit low and spectrally neutral albedo in vims data and may be partly coated with darker hydrocarbons around the southern margin of hotei regio the sar image shows several large dendritic radar bright channels that flow down from the mountainous terrain and terminate in dark blue patches seen in vims images whose infrared color is consistent with enrichment in water ice the patches are in depressions that we interpret to be filled with fluvial deposits eroded and transported by liquid methane in the channels in the vims images the dark blue patches are encased in a latticework of lighter bands that we suggest to demark a set of circumferential and radial fault systems bounding structural depressions conceivably the circular features are tectonic structures that are remnant from an ancient impact structure we suggest that impact generated structures may have simply served as zones of weakness no direct causal connection such as impact induced volcanism is implied we also speculate that two large dark features lying on the northern margin of hotei regio could be calderas in summary the preservation of such a broad suite of vims infrared color variations and the detailed correlation with features in the sar image and sar topography evidence a complex set of geological processes pluvial fluvial tectonic cryovolcanic impact that have likely remained active up to very recent geological time

fluvial erosion and post erosional processes on titan the surface of titan has been revealed by cassini observations in the infrared and radar wavelength ranges as well as locally by the huygens lander instruments sand seas recently discovered lakes distinct landscapes and dendritic erosion patterns indicate dynamic surface processes this study focus on erosional and depositional features that can be used to constrain the amount of liquids involved in the erosional process as well as on the compositional characteristics of depositional areas fluvial erosion channels on titan as identified at the huygens landing site and in radar and visible and infrared mapping spectrometer vims observations have been compared to analogous channel widths on earth yielding average discharges of up to 1600 m3 s for short recurrence intervals that are sufficient to move centimeter sized sediment and significantly higher discharges for long intervals with respect to the associated drainage areas this roughly translates to 1 150 cm day runoff production rates with 10 years recurrence intervals and by assuming precipitation this implies 0 6 60 mm h rainfall rates thus the observed surface erosion fits with the methane convective storm models as well as with the rates needed to transport sediment during cassini s t20 fly by the vims observed an extremely eroded area at 30 w 7 s with resolutions of up to 500 m pixel that extends over thousands of square kilometers the spectral characteristics of this area change systematically reflecting continuous compositional and or particle size variations indicative of transported sediment settling out while flow capacities cease to account for the estimated runoff production and widespread alluvial deposits of fine grained material release of area dependent large fluid volumes are required only frequent storms with heavy rainfall or cryovolcanic induced melting can explain these erosional features

quaternary sea level change and slope instability in coastal areas insights from the vasto landslide adriatic coast central italy abstract this paper focuses on the possible role of sea level change in triggering and controlling large coastal slope instabilities and focuses on the representative case study of the vasto landslide the town of vasto is 143 m a s l and sits atop an uplifted quaternary regressive sequence widely outcropping along the adriatic coast of central italy the coastal slope is affected by large slope instabilities e g vasto landslide including evidence of present activity well documented historical disruptive events affected the town and the coastal slope in 1816 1942 and 1956 field evidence suggests that sea cliff retreat must have removed considerable volumes of rock before the activation of the large slope failures thus a geological evolutionary model of the landslide is proposed here that considers the landforms geological evidence and borehole stratigraphy as well as the combined effect of quaternary uplift and eustatic oscillations on the coastal slope significant evolutionary steps were identified and a slope stability analysis was performed using a stress strain numerical modeling solved by a finite difference method fdm to analyze the following 1 the landslide mechanism 2 the type of activity and 3 the cumulative deformations that occurred during the morpho evolutionary steps numerical modeling was calibrated by considering the present landforms as well as the effects recorded during historical events the results confirm that the vasto landslide was activated in the middle pleistocene 215 ka bp as a consequence of wave cut erosion and progressive uplift of the coastal slope moreover the landslide evolved as a retrogressive single styled landslide comprising two major blocks using this framework the historical events are interpreted as local re activations due to meteorological factors of the ancient rupture surfaces affecting the entire slope

transient rip currents and nearshore circulation on a swell dominated beach 1 eulerian and lagrangian measurements of nearshore circulation on a longshore uniform beach with perpendicularly incident swell waves are described both the eulerian and lagrangian data show a variable rotational part of the current field that is distinct from but coexists with that due to infragravity waves a well defined feature of the flow field includes transient rip currents which occur in varying locations and are not topographically controlled drifter trajectories show that the rips behave like a shallow plane jet consisting of a constrained neck region that flows into a spreading head region there is continuous modulation of the flow within the rip neck estimates of the length scale across the rip neck using two particle statistics are 20 30 m well defined discrete vortex features are observed at the initiation point of one of the necks and in one of the rip heads estimated dispersion values suggest that mixing is greatly enhanced outside the surf zone by the intermittent presence of the rip heads the dispersion calculated from both inside and outside the surf zone appears to show scale dependence with a power law close to 4 3 in a similar way to oceanic turbulence at much larger scales

redundancy and coherence of multi method displacement monitoring data as key issues for the analysis of extremely slow landslides isarco valley eastern alps italy abstract the paper describes the study of two extremely slow active continuous deep seated landslides located in the isarco valley eastern alps italy a multiple rotational rock slide mrrs and partial reactivation of a deep seated gravitational slope deformation dsgsd both landslides interact with viaducts on the e45 highway extensive multi method field investigation monitoring of surface and subsurface displacements and limit equilibrium stability analyses were adopted to fully characterize slope dynamics in order to overcome the limitations due to the systematic errors affecting each single monitoring system and analysis method an operative framework based on redundancy and coherence tests was introduced to check the reliability of the data and results in this framework the geological and geotechnical models of the investigated slopes were progressively refined this allowed assessment of the type of interaction between the slopes and the highway viaducts

equilibrium slopes and cross shore velocity asymmetries in a storm dominated barred nearshore system abstract the near bed 0 10 m elevation horizontal velocities were measured across a two barred lacustrine shoreface during a storm and reveal a spatially coherent but temporally variable pattern in the low order moments of the velocity field large cross shore velocity asymmetries indicated 1 1 spatially extensive and temporally persistent offshore mean flows up to 0 18 m s 1 across the landward slope of the linear outer bar reflecting an undertow driven by a wave induced setup 2 2 an onshore directed skewness opposing the mean flow of wind wave origin and persistent under propagating bores in the inner bar system long after this asymmetry had disappeared from the outer bar extensive sediment reactivation with near zero net sediment flux over the whole of the upper shoreface indicated a sediment prism in a steady state volumetrically over the storm cycle uniform depths of sediment reactivation with zero bed elevation change over the storm cycle revealed local slopes in a steady state in the outer linear bar however time integration of the near bed velocity field at this location indicated an offshore net flux of water while sedimentary structures indicated bedform migration and thus at least bedload almost uniformly onshore when ripples and megaripples were present the sediment transport giving rise to the local equilibrium cannot be explained therefore on the basis of the mean properties of the near bed velocity vector but requires knowledge of the time varying instantaneous sediment transport vector onshore migration of the inner bar correlated well with the large and persistent onshore skewness of the velocity distribution in the inner surf zone associated with translatory surf bores throughout the storm decay period low frequency oscillations were only significant close to the shoreline but may have influenced the development of a sinuous three dimensional inner bar form as it migrated onshore

microwave dielectric constant of liquid hydrocarbons application to the depth estimation of titan s lakes 1 cassini radar reveals the surface of titan since flyby ta acquired on october 2004 the radar instrument discovered volcanic structures craters dunes channels lakes and seas in particular flyby t16 realized in july 2006 imaged tens of radar dark features close to titan s north pole they are interpreted as lakes filled with liquid hydrocarbons mainly methane a key material in the geologic and climatic history of titan in order to perform quantitative analysis and modeling of the radar response of titan s lakes the dielectric constant of liquid hydrocarbons is a crucial parameter in particular to estimate the radar wave attenuation we present here first measurements of the dielectric constant of lng liquefied natural gas mainly composed of methane at ku band 10 13 ghz we obtained a value 1 75 0 002j this value is used to model the radar backscattering of lakes observed during t16 flyby using a two layer scattering model we derive a relationship that is used to estimate a minimum depth for titan s lakes the proposed relationship is also coherent with the observation that the larger and then the deeper lakes are also the darker in radar images

analysis and interpretation of cassini titan radar altimeter echoes abstract the cassini spacecraft has acquired 25 radar altimeter elevation profiles along titan s surface as of april 2008 and we have analyzed 18 of these for which there are currently reconstructed ephemeris data altimeter measurements were collected at spatial footprint sizes from 6 60 km along ground tracks of length 400 3600 km the elevation profiles yield topographic information at this resolution with a statistical height accuracy of 35 50 m and kilometer scale errors several times greater the data exhibit significant variations in terrain from flat regions with little topographic expression to very rugged titanscapes the bandwidth of the transmitted waveform admits vertical resolution of the terrain height to 35 m at each observed location on the surface variations in antenna pointing and changes in surface statistics cause the range compressed radar echoes to exhibit strong systematic and time variable biases of hundreds of meters in delay it is necessary to correct the received echoes for these changes and we have derived correction algorithms such that the derived echo profiles are accurate at the 100 m level for off nadir pointing errors of 0 3 and 0 6 for leading edge and echo centroid estimators respectively the leading edge of the echo yields the elevation of the highest points on the surface which we take to be the peaks of any terrain variation the mean value of the echo delay is more representative of the mean elevation so that the difference of these values gives an estimate of any local mountain heights finding locations where these values diverge indicates higher relief terrain elevation features are readily seen in the height profiles several of the passes show mountains of several hundred m altitude spread over 10 s or even 100 s of km in spatial extent so that slopes are very small large expanses of sub 100 m topography are commonplace on titan so it is rather smooth in many locations other areas exhibit more relief although the overall observed variation in surface height on any pass is less than about 1 km some elevation features correspond to observed changes in brightness in cassini infrared images but many do not correspondence between the imaging sar ground tracks and the altimeter paths is limited so that identifying elevation changes with higher resolution sar features is premature at present

titan s surface from cassini radar sar and high resolution radiometry data of the first five flybys abstract the first five titan flybys with cassini s synthetic aperture radar sar and radiometer are examined with emphasis on the calibration and interpretation of the high resolution radiometry data acquired during the sar mode sar radiometry maps of the 2 cm wavelength brightness temperature are obtained coincident with the sar swath imaging with spatial resolution approaching 6 km a preliminary calibration shows that brightness temperature in these maps varies from 64 to 89 k surface features and physical properties derived from the sar radiometry maps and sar imaging are strongly correlated in general we find that surface features with high radar reflectivity are associated with radiometrically cold regions while surface features with low radar reflectivity correlate with radiometrically warm regions we examined scatterplots of the normalized radar cross section 0 versus brightness temperature finding differing signatures that characterize various terrains and surface features implications for the physical and compositional properties of these features are discussed the results indicate that volume scattering is important in many areas of titan s surface particularly xanadu while other areas exhibit complex brightness temperature variations consistent with variable slopes or surface material and compositional properties

pancakelike domes on venus the shape of seven large domes on the plains of venus with volumes between 100 and 1000 km3 is compared with that of an axisymmetric gravity current spreading over a rigid horizontal surface both the altimetric profiles and the horizontal projection of the line of intersection of domes on the synthetic aperture radar images agree well with the theoretical similarity solution for a newtonian fluid but not with the shape calculated for a rigid plastic rheology nor with that for a static model with a strong skin as a viscous current spreads it generates an isotropic strain rate tensor whose magnitude is independent of radius such a flow can account for the randomly oriented cracks that are uniformly distributed on the surface of the domes the stress induced by the flow in the plains material below is obtained and is probably large enough to produce the short radial cracks in the surface of the plains beyond the domes the viscosity of the domes can be estimated from their thermal time constants if spreading is possible only when the fluid is hot and lies between 1014 and 1017 pa s laboratory experiments show that such viscosities correspond to temperatures of 610 to 700 c in dry rhyolitic magmas these temperatures agree with laboratory measurements of the solidus temperature of wet rhyolite these results show that the development of the domes can be understood using simple fluid dynamical ideas and that the magmas involved can be produced by wet melting at depths below 10 km followed by eruption and degassing

monitoring numerical modelling and hazard mitigation of the moscardo landslide eastern italian alps abstract the moscardo torrent basin eastern italian alps is a high risk site since a large roto translational landslide might dam the torrent with the consequence of increasing the possibility of large debris flow events creating a threat for the infrastructures and the socio economic activities of the villages that dot the valley below the landslide whose volume is estimated 2 million m3 has been monitored since 2006 with inclinometers electric piezometers and a gps network the velocity along the entire body of the landslide averages 1 0 1 5 cm per month the shear surface develops at depths varying from 9 to 10 m to 55 62 m while the groundwater table is almost constant throughout the year despite a cumulative rainfall of the area that usually reaches 2000 mm year the movements were simulated in a numerical model in order to estimate the stabilization effect obtained by different types of possible countermeasures the simulation was carried out using flac 2d with creep modelling visco elasto plastic model of the medium in the sliding zone was assumed allowing to determine the relation between time and displacement a 10 year displacement trend starting from the initial situation of 2006 was simulated moreover seismic conditions were taken into consideration with a quasi static approach by applying a horizontal acceleration the numerical model was built and validated on the basis of the data retrieved from geological investigations as well as from inclinometric and gps measurements the results show that an accurate and well planned multidisciplinary approach can help the decision makers in the choice of the most effective engineering solution for the mitigation of landslide hazard and risk

a giant deep seated slope deformation in the italian alps studied by paleoseismological and morphometric techniques this work proves the existence of a large deep seated gravitational slope deformation dgsd in a hilly region of the southwestern alps whereas dgsd are usually linked with high relief energy in mountain environments moreover we describe the usefulness of applying paleoseismological techniques by means of trench excavation to date and understand the deformation history and genesis of recent morphostructures and we found evidence of causative relationships between dgsd and surface landslides the studied dgsd of mt croce della tola mt scincina italy is the largest of the western alps it is 7 km long and involves a minimum area of 16 km2 with a volume 3 5 km3 probably extending further ne beneath lake maggiore surface several parallel scarps representing the surface expression of slip planes affect the upper part of the slope whereas the lower part presents a convex profile dgsd at mt croce della tola started in the last interglacial period 120 40 ka bp and the following glacial phase was not able to significantly modify the general slope geometry post glacial deformation also occurred especially at mt scincina after 25 ka bp post glacial and active surface landslides developed on the convex lower part of the slope suggesting that they resulted from instability due to the new profile assumed by the slopes during the deep seated deformation the occurrence of mt scincina dgsd with a very low topographic gradient is interpreted as an effect induced by on other large dgsd

scale in gis an overview scale has many meanings but in gis two are of greatest significance resolution and extent ideally models of physical process would be defined and tested on scale free data in practice spatial resolution will always be limited by cost data volume and other factors raster data are shown to be preferable to vector data for scientific research because they make spatial resolution explicit the effects of resolution are discussed for two simple gis functions three theoretical frameworks for discussing spatial resolution are introduced and explored the problems of cross scale inference including the modifiable areal unit problem and the ecological fallacy are described and illustrated

prerequisites for explosive cryovolcanism on dwarf planet class kuiper belt objects explosive extrusion of cold material from the interior of icy bodies or cryovolcanism has been observed on enceladus and perhaps europa triton and ceres it may explain the observed evidence for a young surface on charon pluto s surface is masked by frosts here we evaluate prerequisites for cryovolcanism on dwarf planet class kuiper belt objects kbos we first review the likely spatial and temporal extent of subsurface liquid proposed mechanisms to overcome the negative buoyancy of liquid water in ice and the volatile inventory of kbos we then present a new geochemical equilibrium model for volatile exsolution and its ability to drive upward crack propagation this novel approach bridges geophysics and geochemistry and extends geochemical modeling to the seldom explored realm of liquid water at subzero temperatures we show that carbon monoxide co is a key volatile for gas driven fluid ascent whereas co 2 and sulfur gases only play a minor role n 2 ch 4 and h 2 exsolution may also drive explosive cryovolcanism if hydrothermal activity produces these species in large amounts a few percent with respect to water another important control on crack propagation is the internal structure a hydrated core makes explosive cryovolcanism easier but an undifferentiated crust does not we briefly discuss other controls on ascent such as fluid freezing on crack walls and outline theoretical advances necessary to better understand cryovolcanic processes finally we make testable predictions for the 2015 new horizons flyby of the pluto charon system

the interaction between active normal faulting and large scale gravitational mass movements revealed by paleoseismological techniques a case study from central italy paleoseismological techniques have been applied to characterize the kinematic behaviour of large scale gravitational phenomena located in proximity of the seismogenic fault responsible for the mw 7 0 1915 avezzano earthquake and to identify evidence of a possible coseismic reactivation the above mentioned techniques were applied to the surface expression of the main sliding planes of the mt serrone gravitational deformation located in the southeastern border of the fucino basin central italy the approach allows us to detect instantaneous events of deformation along the uphill facing scarp these events are testified by the presence of faulted deposits and colluvial wedges the identified and chronologically constrained episodes of rapid displacement can be probably correlated with seismic events determined by the activation of the fucino seismogenic fault affecting the toe of the gravitationally unstable rock mass indeed this fault can produce strong short term dynamic stresses able to trigger the release of local gravitational stress accumulated by mt serrone s large scale gravitational phenomena the applied methodology could allow us to better understand the geometric and kinematic relationships between active tectonic structures and large scale gravitational phenomena it would be more important in seismically active regions since deep seated gravitational slope deformations can evolve into a catastrophic collapse and can strongly increase the level of earthquake induced hazards

mylitta fluctus venus rift related centralized volcanism and the emplacement of large volume flow units mylitta fluctus is a volcanic flow field that covers approximately 300 000 km2 in southern lavinia planitia the flows are typically radar bright with uniform surface textures central channels are common maximum flow lengths range from 400 to 1000 km flow widths range 30 100 km in the medial and distal portions of the flow field the total volume of the flow field based on estimates of flow thickness is of the order of 2 104 km3 the flow field is composed of six smaller flow fields that are interpreted to represent major eruption events in the evolution of mylitta an asymmetric shield volcano 200 km in radius with a central caldera has been identified as the single major source it is located along a possible rift zone at the northern edge of lada terra no evidence for fissure fed eruptions is observed although eruptions may have occurred along fissures within the rift before the main vent centralized mylitta is similar in scale to many terrestrial flood basalt provinces although it is lower in total estimated volume and is distinguished by the presence of a central source edifice the origin of mylitta is proposed to be linked to regional extension and possible hotspot activity in a manner similar to that suggested for the origin of terrestrial flood basalts the lower apparent volume of mylitta relative to terrestrial flood basalts suggests that the amount of material upwelling from the mantle may have been lower in this case or that the formation of the flow field has not yet finished detailed studies of the morphology and distribution of flow fields similar to mylitta should yield insight into the variation and evolution of hotspot related volcanism and the formation of possible flood basalts on venus

rip current type spacing and persistence narrabeen beach australia abstract long term daily rip observations on narrabeen beach australia were made together with daily measurements of wave height period direction surf zone width and beach state a total of 3513 rips were observed on 270 days over a 19 month period results show that rips accompany moderate to high waves and are associated with intermediate beach types rip spacing follows wave conditions increasing in spacing size and intensity as waves rise and conversely as they fall rips are a function of both the prevailing and antecedent wave conditions and the rate and direction of change in wave conditions rips are classified into three types erosion mega and accretion erosion rips are initiated by rising seas in the transverse bar and rip and higher beach states they accompany general beach erosion they are widely spaced narrabeen ys 300 500 m 100 200 m increasing in size and intensity with the waves until the fully dissipative ripless state is reached they are both temporally and spatially highly variable persisting in one location for only hours to a day or so except where topographically controlled they are a major mechanism for the seaward transport of sediment and under extreme conditions may extend over a kilometer seaward of the breaker zone mega rips are large scale 1 km topographically controlled erosion rips that persist when nearshore and or embayment topography prevents the development of the fully dissipative state by inducing wave refraction and persist longshore gradients in surf zone dynamics that in turn drive the rip circulation accretion rips prevail during stable or falling wave conditions usually following erosion rip formation they are associated with general beach accretion are more closely spaced narrabeen ys 170 250 m 100 m less intense and become increasingly topographically arrested by crescentic bars and rhythmic bar beach morphology of the longshore bar trough rhythmic bar and beach and transverse bar and rip beach states they are relatively stable both spatially and temporally and may persist in one location for days to weeks if wave conditions remain favorable they are fair weather rips which may disappear by infilling in the low tide terrace beach state or be destroyed by rising seas rips generally are absent from the reflective low tide terrace and fully dissipative beach states

structural constraints on deep seated slope deformation kinematics abstract a significant sackung type deep seated slope gravitational deformation dsgsd was recognised for the first time by the authors in the middle part of valfurva east of bormio rhaetian alps italy the reconstruction of its kinematics age and state of activity is presented through a detailed description of its morphological geomechanical and structural features an integrated multi disciplinary approach was performed to achieve a clear comprehension of the phenomenon field surveys and aero photo interpretation were carried out in order to clarify the structural geological and geomorphological setting in which the dsgsd developed a kinematic conceptual model of the slope deformation was developed through the analysis of morpho structures of their significance and relationships with lithological markers and quaternary deposits after a geomechanical characterisation of the rock mass involved in the slope deformation numerical modelling was performed to verify the hypotheses made on kinematics and driving factors of the phenomenon the sackung affects pre permian metapelites metabasites and marbles belonging to the upper austroalpine basement of the campo nappe as well as late pleistocene and holocene glacial and rock glacier deposits the deformation started after the late wurmian age 15 000 11 000 years b p and continued until few centuries ago not excluding a present day low rate activity deformation consists in a large oblique sagging along a deep confined sliding surface associated with gravitational reactivation of pre existing late alpine and recent tectonic brittle structures leading to the formation of n s and wnw ese trending gravitational morpho structures the evolution of the wnw ese trending system resulting in asymmetric trenches led to progressive failure of the lower part of the slope during the last 10 000 years as testified by large paleo landslide accumulations and it is still in progress numerical modelling indicates post glacial unloading as the main triggering factor of the slope deformation the importance of this deep seated slope deformation is enhanced by the occurrence of the 30 mm 3 active ruinon landslide in the lower part of the slope such landslide is subjected to rapid evolution and threatens the valley floor establishing an important risk factor connected to human lives and socio economic activities

alluvial and fluvial fans on saturn s moon titan reveal processes materials and regional geology fans landforms that record the storage and transport of sediment from uplands to depositional basins are found on saturn s moon titan a body of significantly different process rates and material compositions from earth images obtained by the cassini spacecraft s synthetic aperture radar reveal morphologies roughness textural patterns and other properties consistent with fan analogues on earth also viewed by synthetic aperture radar the observed fan characteristics on titan reveal some regions of high relative relief and others with gentle slopes over hundreds of kilometres exposing topographic variations and influences on fan formation there is evidence for a range of particle sizes across proximal to distal fan regions from c 2 cm or more to fine grained which can provide details on sedimentary processes some features are best described as alluvial fans which implies their proximity to high relief source areas while others are more likely to be fluvial fans drawing from larger catchment areas and frequently characterized by more prolonged runoff events the presence of fans corroborates the vast liquid storage capacity of the atmosphere and the resultant episodic behaviour fans join the growing list of landforms on titan derived from atmospheric and fluvial processes similar to those on earth strengthening comparisons between these two planetary bodies

waves currents sediment flux and morphological response in a barred nearshore system abstract a shore normal array of seven bi directional electromagnetic flowmeters and nine surface piercing continuous resistance wave staffs were deployed across a multiple barred nearshore at wendake beach georgian bay canada and monitored for a complete storm cycle time integrated estimates of total itvf and net invf sediment volume flux together with bed elevation changes were determined using depth of activity rods the three bars ranging in height from 0 10 to 0 40 m accreted during the storm 0 03 m and the troughs were scoured 0 05 m sediment reactivation depths reached 0 14 m and 12 of the nearshore control volume was mobilized however the invf value for the storm was less than 1 of the control volume revealing a near balance in sediment volume in the bar system landward migration of the inner crescentic and second sinuous bars occurred in association with an alongshore migration of the bar form itself the outermost straight shore parallel bar remained fixed in location the surf zone was highly dissipative throughout the storm 3 8 10 2 192 10 2 and the wave spectrum was dominated by energy at the incident frequency spectral peaks at frequencies of the first harmonic and at one quarter that of the incident wave were associated with secondary wave generation just prior to breaking and a standing edge wave respectively the former spectral peak was within the 95 confidence band for the spectrum while the latter contributed not more than 10 to the total energy in the surface elevation spectrum even near the shoreline during the storm wave height exceeded 2 m h s and periods reached 5 s t p k orbital velocities exceeded 0 5 m s 1 u rm s and were above the threshold of motion for the medium to fine sands throughout the storm shore parallel flows in excess of 0 4 m s 1 were recorded with maxima in the troughs and minima just landward of the bar crest the rate and direction of sediment flux is best explained by the interaction of antecedent bed slopes with spatial gradients in the mean and asymmetry of the shore normal velocity field these hydrodynamic parameters represent steady flows superimposed on the dominantly oscillatory motion and assumed a characteristic spatial pattern from the storm peak through the decay period increases spatially in the magnitudes of both the mean flows and flow asymmetries cause an increasing net transport potential erosion decreases in these values spatially cause a decreasing net transport potential and thus deposition these transport potentials are increased or decreased through the gravity potential induced by the local bed slope shore parallel flow was important in explaining sediment flux and morphological change where orbital velocities mean flows and flow asymmetries were at a minimum

modeling cryogenic mud volcanism on pluto abstract subsurface ice cryofluids and ice interactions with ammonia for cryovolcanic materials give the potential ingredients for the formation of mud volcanoes on pluto in order to constrain the possible morphology from images acquired by the new horizons spacecraft we have modeled the formation of mud volcanoes isostatic layers of ice overlain by denser material from a series of possible solid liquid mud compositions methane and ammonia as well as accounting for the full range of eruption variables e g mud viscosity conduit diameter and eruption duration we categorize them into nine specific scenarios based on the composition of the top ice layer and mud composition from these scenarios the maximum height of the potential mud volcano can be calculated we find that ammonia mud sources produce smaller edifice heights and wider flow profiles compared to methane dominant mud cryovolcanoes assuming certain preliminary parameters we also propose the evolution and development of the edifice of wright mons in as little as 3 8 million years given a 10 wt ammonia subsurface mud composition if characterized on pluto s surface mud volcanoes would provide an interesting insight on the subsurface dynamics of solids and cryofluids on pluto

radar scattering of linear dunes and mega yardangs application to titan the ku band 13 8 ghz 2 2 cm radar instrument onboard the cassini huygens spacecraft has revealed the richness of the surface of titan as numerous seas lakes rivers cryo volcanic flows and vast dune fields have been discovered linear dunes are a major geomorphological feature present on titan covering up to 17 of its surface mainly in equatorial regions however the resolution of the radar instrument is not good enough to allow a detailed study of the morphology of these features in addition other linear wind related landforms such as mega yardangs linear wind abraded ridges formed in cohesive rocks are likely to present a comparable radar signature that could be confused with the one of dunes we conducted a comparative study of the radar radiometry of both linear dunes and mega yardangs based on representative terrestrial analogues the linear dunes located in the great sand sea in western egypt and in the namib desert in namibia and the mega yardangs observed in the lut desert in eastern iran and in the borkou desert in northern chad we analysed the radar scattering of both terrestrial linear dunes and mega yardangs using high resolution radar images acquired by the x band 9 6 ghz 3 1 cm sensor of the terrasar x satellite variations seen in the radar response of dunes are the result of a contrast between the dune and interdune scattering while for mega yardangs these variations are the result of a contrast between ridges and erosion valleys we tested a simple surface scattering model with parameters derived from the local topography and surface roughness estimates to accurately reproduce the radar signal variations for both landforms it appears that we can discriminate between two types of dunes bare interdunes as in egypt and sand covered interdunes as in namibia and between two types of mega yardangs young yardangs as in iran and older ones as in chad we applied our understanding of the radar scattering to the analysis of cassini radar t8 acquisitions over the belet sand sea on titan and show that the linear dunes encountered there are likely to be of both egyptian and namibian type we also show that the radar bright linear features observed in cassini radar t64 and t83 acquisitions are very likely to be mega yardangs possible remnants of ancient lake basins at mid latitude formed when titan s climate was different

resurfacing of titan by ammonia water cryomagma the cassini titan radar mapper observed on titan several large features interpreted as cryovolcanic during the october 26 2004 pass at high northern latitudes lopes r m c and 43 colleagues 2007 icarus 186 395 412 to date models of ammonia water resurfacing have not been tied to specific events or evolutionary stages of titan we propose a model of cryovolcanism that involves cracking at the base of the ice shell and formation of ammonia water pockets in the ice as these ammonia water pockets undergo partial freezing in the cold ice shell the ammonia concentration in the pockets increases decreasing the negative buoyancy of the ammonia water mixture if the ice shell is contaminated by silicates delivered in impacts the liquid solid density difference would be even less while the liquid cannot easily become buoyant relative to the surrounding ice these concentrated ammonia water pockets are sufficiently close to the neutral buoyancy point that large scale tectonic stress patterns tides non synchronous rotation satellite volume changes solid state convection or subsurface pressure gradients associated with topography would enable the ammonia to erupt effusively onto the surface rather than suggesting steady state volcanism over the history of the solar system we favor a scenario where the cryovolcanic features could have been associated with episodic potentially late geological activity

geophysical survey to estimate the 3d sliding surface and the 4d evolution of the water pressure on part of a deep seated landslide geophysical surveys were conducted on the very unstable front part of the la clapiere landslide in the french alps alpes maritimes the electrical resistivity survey was carried out to obtain for the first time on this deep seated landslide 3d information on the slipping surface and the vertical drained faults moreover we planned to follow within time 6 months the evolution of the saturated zones presence of gravitational water and their percolation into the shearing zones our 4d results showed the importance of the complex water channelization within the slope and relation to geological discontinuities

experimental study of nearshore dynamics on a barred beach with rip channels 1 wave and current measurements are presented from a set of laboratory experiments performed on a fixed barred beach with periodically spaced rip channels using a range of incident wave conditions the data demonstrate that the presence of gaps in otherwise longshore uniform bars dominates the nearshore circulation system for the incident wave conditions considered for example nonzero cross shore flow and the presence of longshore pressure gradients both resulting from the presence of rip channels are not restricted to the immediate vicinity of the channels but instead are found to span almost the entire length of the longshore bars in addition the combination of breaker type and location is the dominant driving mechanism of the nearshore flow and both are found to be strongly influenced by the variable bathymetry and the presence of a strong rip current the depth averaged currents are calculated from the measured velocities assuming conservation of mass across the measurement grid the terms in both the cross shore and longshore momentum balances are calculated and their relative magnitudes are quantified the cross shore balance is shown to be dominated by the cross shore pressure and radiation stress gradients in general agreement with previous results however the rip current is shown to influence the wave breaking and the wave induced setup in the rip channel analysis of the longshore balance shows that the overall strength of the longshore feeder currents is governed by a balance between longshore pressure gradient forcing and an opposing radiation stress gradient in addition the longshore feeder currents show maxima in the bar trough region providing experimental evidence that longshore pressure gradients can shift longshore current maxima shoreward from the bar crest finally since the longshore radiation stress gradient in the surf zone is governed by the amount of wave dissipation on the rip current there exists a positive feedback mechanism whereby a strong rip current can weaken the radiation stress gradient opposing the feeder currents and lead to even stronger feeder currents and rips

distribution and interplay of geologic processes on titan from cassini radar data abstract the cassini titan radar mapper is providing an unprecedented view of titan s surface geology here we use synthetic aperture radar sar image swaths ta t30 obtained from october 2004 to december 2007 to infer the geologic processes that have shaped titan s surface these sar swaths cover about 20 of the surface at a spatial resolution ranging from 350 m to 2 km the sar data are distributed over a wide latitudinal and longitudinal range enabling some conclusions to be drawn about the global distribution of processes they reveal a geologically complex surface that has been modified by all the major geologic processes seen on earth volcanism tectonism impact cratering and erosion and deposition by fluvial and aeolian activity in this paper we map geomorphological units from sar data and analyze their areal distribution and relative ages of modification in order to infer the geologic evolution of titan s surface we find that dunes and hummocky and mountainous terrains are more widespread than lakes putative cryovolcanic features mottled plains and craters and crateriform structures that may be due to impact undifferentiated plains are the largest areal unit their origin is uncertain in terms of latitudinal distribution dunes and hummocky and mountainous terrains are located mostly at low latitudes less than 30 with no dunes being present above 60 channels formed by fluvial activity are present at all latitudes but lakes are at high latitudes only crateriform structures that may have been formed by impact appear to be uniformly distributed with latitude but the well preserved impact craters are all located at low latitudes possibly indicating that more resurfacing has occurred at higher latitudes cryovolcanic features are not ubiquitous and are mostly located between 30 and 60 north we examine temporal relationships between units wherever possible and conclude that aeolian and fluvial pluvial lacustrine processes are the most recent while tectonic processes that led to the formation of mountains and xanadu are likely the most ancient

ripex observations of a rip current system rip current kinematics and beach morphodynamics were measured for 44 days at sand city monterey bay ca using 15 instruments composed of co located velocity and pressure sensors acoustic doppler current profilers and kinematic gps surveys the morphology consisted of a low tide terrace with incised quasi periodic rip channels representative of transverse bars offshore 17 m depth significant wave height and peak period ranged 0 20 3 0 m and 5 20 s the mean wave direction was consistently near 08 resulting in rip channel morphology which evolved in response to the changing wave characteristics an inverse relationship between sediment accreting on the transverse bar and eroding in the rip channel was found the spatial distribution of sediment is reflected in the background rip current flow field the mean velocity magnitudes within the rip channel transverse bars increased offshore onshore with decreasing tidal elevations and increased with increasing sea swell energy eulerian averaged flows were predominantly shoreward on the transverse bars and seaward within the rip channel throughout the experiment resulting in a persistent cellular circulation except during low wave energy the rip current spacing to the rip channel width was less than or equal to two which suggests that the rip currents are influenced by each other and that no two dimensional bar return flow should be present the vertical velocity profile on the bar indicated that the flow was predominantly shoreward the flow field within the surf zone was depth uniform except for significant shear occurring near the surface owing to stokes drift the wave induced transport hypothesis is evaluated d 2005 elsevier b v all rights reserved

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

rip current review rip currents are shore normal narrow seaward flowing currents that originate within surf zone extend seaward of the breaking region rip head and can obtain relatively high velocities within the last decade there have been a significant number of laboratory and field observations within rip current systems an overview of rip current kinematics based on these observations and the scientific advances obtained from these efforts are synthesized rip current flows are partitioned into mean infragravity very low frequency vorticity and tidal contributions and it is found that each contributes significantly to the total data from the laboratory and the field suggest that the rip current strength increases with increasing wave energy and decreasing water depths the maximum mean current occurs inside the surf zone where the maximum forcing is present owing to the dissipation of waves

tracer test to assess flow and transport parameters of an earth slide the montecagno landslide case study italy abstract subsurface water processes are principle triggering and driving factors during slope movements however the hydraulic properties that drive groundwater flow along the slope remain poorly understood moreover landslide deposits are often characterized by layering and fissures that cause high heterogeneity in the distribution of hydraulic properties this heterogeneity leads to great uncertainty in the prediction of groundwater flow paths this study aimed to improve understanding of hydraulic and transport properties of deep earth slides and to identify preferential flow directions inside the landslide body a dye tracer test was used to estimate transport parameters and characterize groundwater flow paths the results indicate that in the studied landslide two groundwater flow types exist and are related to the presence of fissured rock blocks and debris horizons embedded in a fine matrix the estimated low groundwater flow velocity has rarely been estimated in other studies of this landslide type the groundwater flow direction appears to be mainly influenced by the failure surface shape and differs from the sliding direction our results differ from those in other landslide studies and improve our knowledge of groundwater flow properties in deep earth slides furthermore they offer a new contribution to slope stability analyses and formula and to the effective design of mitigation strategies

the tectonics of titan global structural mapping from cassini radar abstract the cassini radar mapper has imaged elevated mountain ridge belts on titan with a linear to arcuate morphology indicative of a tectonic origin systematic geomorphologic mapping of the ridges in synthetic aperture radar sar images reveals that the orientation of ridges is globally e w and the ridges are more common near the equator than the poles comparison with a global topographic map reveals the equatorial ridges are found to lie preferentially at higher than average elevations we conclude the most reasonable formation scenario for titan s ridges is that contractional tectonism built the ridges and thickened the icy lithosphere near the equator causing regional uplift the combination of global and regional tectonic events likely contractional in nature followed by erosion aeolian activity and enhanced sedimentation at mid to high latitudes would have led to regional infilling and perhaps covering of some mountain features thus shaping titan s tectonic landforms and surface morphology into what we see today

mean currents and sediment transport in a rip channel measurements of hydrodynamics and suspended sediment transport were carried out along a cross shore transect in a rip channel a tidally induced threshold for rip flow initiation was found this threshold depended upon the degree of wave energy dissipation and could be identified through a critical value of the ratio of significant wave height to water depth s in the rip neck with normally incident waves rip current velocities were well correlated with velocities predicted from a simple model involving the onshore mass transport in asymmetric breaking waves crossing the bar hydrodynamics and sediment transport were tidally modulated with strong offshore directed rip currents and associated offshore sediment transport due to the mean flow at low tide at high tide when the rip was inactive the tendency was for weak onshore directed mean flows and or oscillatory incident waves transporting smaller amounts of sediment landward the net result was a gradual lowering of the topographic relief along the rip channel with net deposition seaward of the rip outside the surf zone transport was mainly landward due to oscillatory incident waves

cassini radar images at hotei arcus and western xanadu titan evidence for geologically recent cryovolcanic activity 1 images obtained by the cassini titan radar mapper radar reveal lobate flowlike features in the hotei arcus region that embay and cover surrounding terrains and channels we conclude that they are cryovolcanic lava flows younger than surrounding terrain although we cannot reject the sedimentary alternative their appearance is grossly similar to another region in western xanadu and unlike most of the other volcanic regions on titan both regions correspond to those identified by cassini s visual and infrared mapping spectrometer vims as having variable infrared brightness strengthening the case that these are recent cryovolcanoes citation wall s d et al 2009 cassini radar images at hotei arcus and western xanadu titan evidence for geologically recent cryovolcanic activity geophys res lett 36 l04203 doi 10 1029 2008gl036415

the landscape of titan as witness to its climate evolution we investigated the range of titan climate evolution hypotheses regulated by the role sources and availability of methane we analyzed all available image data principally synthetic aperture radar sar of titan s landscape through the t 86 encounter starting with focused examinations of terrains that carry the markers of climate evolution traditional geologic and geomorphic landscape analysis was used to perform morphometric characterization establish time stratigraphic relationships and interpret local and regional geologic process oriented evolutionary histories we then assayed the distribution of terrains we identified with respect to both their latitudinal and altimetric occurrence our analysis of the terrain types and distributions was used to evaluate and rank the various climate evolution scenarios we favor progressive hypotheses which include a relatively brief period in which precipitation was able to affect geomorphic change in low latitudes at scales perceivable in sar data with subsequent gradual decline of precipitation intensity coupled with an increasing poleward restriction

loess and life out of earth abstract loess is a homogeneous typically nonstratified porous friable slightly coherent often calcareous fine grained silty pale yellow wind blown aeolian and often by water reworked sediment that is distributed on continents world wide recent studies have highlighted the importance of biological loess crusts in trapping and transforming aeolian material into loess and also in prevention from wind and water erosion of deposited material some planets and satellites in our solar system are characterized by conditions comparable to those related to loess formation in terrestrial environments given the requirements for loess deposition on earth this study aims to ask the following questions 1 if loess like sediment formation is possible outside earth what are the mechanisms of sediment deposition and preservation 2 could the possible loess like sediments be stabilized through the activity of extraterrestrial equivalents of biological loess crusts found on earth as loess formation on earth is related to biological activity we propose a new direction in the search for extraterrestrial life evidence about extraterrestrial loess might indicate extraterrestrial life connected to loess formation on the basis of comparative analysis of some astrophysical conditions of seven celestial bodies we propose mars and titan and possibly venus and io to be assessed for evidence of loess deposition and the possible presence of related life forms and their biomarkers following recent advances in our understanding of terrestrial loess deposition we propose new indicators of extraterrestrial life research biomarkers in loess cyanobacterial and other microbial

titan radar mapper observations from cassini s t3 fly by cassini s titan radar mapper imaged the surface of saturn s moon titan on its february 2005 fly by denoted t3 collecting high resolution synthetic aperture radar and larger scale radiometry and scatterometry data these data provide the first definitive identification of impact craters on the surface of titan networks of fluvial channels and surficial dark streaks that may be longitudinal dunes here we describe this great diversity of landforms we conclude that much of the surface thus far imaged by radar of the haze shrouded titan is very young with persistent geologic activity

structures along the orobic thrust central orobic alps italy a series of regional deformation phases is described for the metamorphic basement and the permian cover in an area in the central orobic alps northern italy in the basement deformation under low grade amphibolite metamorphic conditions is followed by a second phase during retrograde greenschist conditions these two phases predate the deposition of the permian cover and are of probable variscan age an extensional basin formed on the eroded basement during the late carboniferous filled with fan conglomerates and sandstones and rhyolitic volcanic rocks well preserved brittle extensional faults bound these basins further extension deformed basement and cover before the onset of alpine compressional tectonics cover and basement were deformed together during two phases of compressional deformation of post triassic age the first giving rise to tectonic inversion of the older extensional faults the second to new thrust faults both associated with south directed nappe emplacement and regional folding foliations develop in the cover only during the first phase of deformation as part of the activity on shortening faults main activity on the orobic thrust actually postdates the first phase of thrusting and foliation development in the cover

a trend surface technique for discrimination of surf zone morphology rip current channels a major problem facing coastal nearshore studies is the conversion of survey data to precise two and three dimensional representations of complex surf zone topography in addition to inherent problems in providing accurate survey data most signi cant topographical boundaries are often delineated in a subjective manner a trend surface technique is hereby presented which provides an objective rigorous and replicable method of identifying morphological rip system channel boundaries in the surf zone using an extensive eld dataset obtained over two eld experiments including an almost complete cycle of low energy intermediate beach state evolution this technique is shown to produce accurate planimetric dimensions for a range of topographic beach state morphologies previously absent or highly descriptive in the literature formal morphometric de nitions of geometric dimensions for rip morphologies including rip channel width relief depth and cross sectional areas are provided several new aspects of rip current morphology are discussed from results of the approach the approach described here is also intended to illustrate the potential for future trend surface applications to surf zone and other geomorphological studies copyright 2003 john wiley sons ltd

morphodynamics of a large scale rip current system at muriwai beach new zealand abstract field measurements of rip spacing nearshore morphology water surface elevation and eulerian and lagrangian flows were made in order to investigate the morphodynamics of a large scale rip current system at muriwai beach new zealand muriwai is a high energy meso tidal beach characterised by modal breaker wave heights of 2 5 m and incident wave periods of 10 15 s the monitored rip system was characterised by a 400 m long 75 m wide longshore feeder channel and a 150 m wide rip neck channel oriented obliquely to the shore and extending over a distance of almost 400 m during the experiment the beach evolved from a longshore bar trough and rip state to a transverse bar and rip configuration mean eulerian flow velocities obtained from ducted flowmeters deployed on the margin of the feeder channel and rip neck were on the order of 1 m s 1 and instantaneous flows were commonly in excess of 2 m s 1 mean lagrangian surface flow velocities extending from the base of the feeder through to the rip head were obtained by tracking rip floaters and were on the order of 0 7 m s 1 with maximums in the rip neck region of 1 4 m s 1 a distinct tidal modulation of rip current flow existed with maximum velocities occurring at low tide and minimum velocities at high tide comparison with other rip studies suggests that although the magnitude of the morphodynamic and hydrodynamic processes occurring within large scale rip systems is extreme the behaviour of these rip systems is very similar to low energy rips with much smaller spatial scales there is evidence to suggest that distinct morphodynamic scaling relationships exist between these environments

flow characteristics at the rip current neck under low energy conditions abstract this paper presents the flow signature of the rip current neck as determined by fourteen near bottom velocity records with a comparison made to 63 recordings in the surf zone the field experiments including wave monitoring and morphological mapping were conducted under relatively calm dissipative wave conditions tsig 3 6 s hsig 0 3 1 1 m at herzliya beach israel on the mediterranean shore the current data were analysed for shore normal and resultant components the processing of the time series in the form of instantaneous and smoothed velocities provided spectral energy orbital and current velocity specific current discharge and directional distribution data the unique characteristic of the neck environment was found to be its continuous unidirectional seaward flow due to the channeling effect this steady offshore drift constituted the fastest flow in the surf zone with a typically narrow 35 94 directional range through spectral analysis of the unidirectional return flow the morphodynamic process signature at the rip neck was defined by the relative contribution from the incident waves 78 the subharmonic edge waves 14 and the infragravity oscillations 8 the pulsatory jet like rip model with concentration of energy at low frequencies is not corroborated by this study the studied environment of the rip and bar pattern represented an inherited beach morphology at an initial accretional although not yet reflective stage

the role of the spatial scale and data accuracy on deep seated gravitational slope deformation modeling the ronco landslide italy abstract in recent decades numerical models have been developed and extensively used for landslide hazard and risk assessment the reliability of the outcomes of these numerical simulations must be evaluated carefully as it mainly depends on the soundness of the physical model of the landslide that in turn often requires the integration of several surface and subsurface surveys in order to achieve a satisfactory spatial resolution merging diverse sources of data may be particularly complex for large landslides because of intrinsic heterogeneity and possible great data uncertainty in this paper we assess the spatial scale and data accuracy required for effective numerical landslide modeling we focus on two particular aspects the model extent and the accuracy of input datasets the ronco landslide a deep seated gravitational slope deformation dsgsd located in the north of italy was used as a test bed geological geomorphological and geophysical data were combined and as a result eight models with different spatial scales and data accuracies were obtained the models were used to run a back analysis of an event in 2002 during which part of the slope moved after intense rainfalls the results point to the key role of a proper geomorphological zonation to properly set the model extent the accuracy level of the input datasets should also be tuned we suggest applying the approach presented here to other dsgsds with different geological and geomorphological settings to test the reliability of our findings

nearshore water motion and mean flows in a multiple parallel bar system abstract measurements of surface waves and nearshore water motion were made with wave staffs and electromagnetic currentmeters across the straight outer bars of a multiple parallel bar system at wasaga beach georgian bay ontario three sets of experiments were carried out between 1983 and 1985 and this paper examines the characteristics of spatial and temporal variations in incident waves and mean flows incident wave spectra during storms are typical of fetch limited conditions with a prominent peak in the wind wave frequency and a sharp cut off towards lower frequencies there is little evidence of significant energy at infragravity frequencies mean flows perpendicular to the shoreline during storms measured at 0 1 m above the bed are offshore with speeds of 0 04 0 10 m s 1 during moderate storms and 0 25 m s 1 during intense fall storms longshore currents are relatively weak and their direction closely follows changes in the incident wind angle about shore perpendicular there is no evidence of rip cell development and offshore return flow occurs as an undertow uniformly alongshore forming a simple two dimensional net circulation pattern the presence of the undertow very close to the bed is an important control on the direction of suspended sediment transport and thus in maintaining the equilibrium of the nearshore bars

precedent long term gravitational deformation of large scale landslides in the three gorges reservoir area china abstract large scale landslides are common in the three gorges reservoir region due to steep slopes and complex geological conditions fluctuations of reservoir level etc many phenomena and formation mechanisms related to these landslides are not well understood and need more research in this study large scale landslide evolution and formation mechanisms are thoroughly investigated in terms of precedent long term gravitational deformation pltgd three large scale landslides in the three gorges reservoir region huangtupo landslide htpl huanglashi landslide hlsl and baotaping landslide btpl are taken for example to discuss their phenomena and features of pltgd and to investigate the correlation between the pltgds and landslide many features associated with landslides are caused by slow downslope gravitational processes before landslide failure and three criteria for recognition of the pltgd features are summarized the investigation results reveal that the pltgds play an important role in landslide evolution and formation mechanism overall this paper presents evidences for pltgds of large scale landslides and their correlation with landslide evolution which is helpful to understand the formation mechanism of large scale landslides in the three gorges reservoir region

titan s inventory of organic surface materials 1 cassini radar observations now permit an initial assessment of the inventory of two classes presumed to be organic of titan surface materials polar lake liquids and equatorial dune sands several hundred lakes or seas have been observed of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on earth dark dunes cover some 20 of titan s surface and comprise a volume of material several hundred times larger than earth s coal reserves overall however the identified surface inventories 3 104 km3 of liquid and 2 105 km3 of dune sands are small compared with estimated photochemical production on titan over the age of the solar system the sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters the lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term but do not contain enough methane to sustain the atmosphere over geologic time unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate dramatic climate change on titan is likely in its past present and future

morphodynamics of a bar trough surf zone abstract a field study was made of the distinguishing morphodynamic processes operating in a surf zone which perennially exhibits accentuated bar trough topography the longshore bar trough and rhytmic bar and beach states as described by wright and short 1984 characteristic features of the morphology include a shallow bar with a steep shoreward face a deep trough and a steep beach face this morphology which is favored by moderate breaker heights and small tidal ranges strongly controls the coupled suite of hydrodynamic processes in contrast to fully dissipative surf zones the bar trough surf zone is not at all saturated and oscillations at incident wave frequency remain dominant from the break point to the subaerial beach the degree of incident wave groupiness does not change appreciably across the surf zone infragravity standing waves which in dissipative surf zones dominate the inshore energy remain energetically secondary and occur at higher frequencies in the bar trough surf zone analyses of the field data combined with numerical simulations of leaky mode and edge wave nodal antinodal positions over observed surf zone profiles indicate that the frequencies which prevail are favored by the resonant condition of antinodes over the bar and nodes in the trough standing waves which would have nodes over the bar are suppressed sediment resuspension in the surf zone appears to be largely attributable to the incident waves which are the main source of bed shear stress in addition the extra near bottom eddy viscosity provided by the reformed non breaking waves traversing the trough significantly affects the vertical velocity profile of the longshore current whereas the bar is highly mobile in terms of onshore offshore migration rates the beach face and inner regions of the trough are remarkably stable over time

surface albedo spectral properties of geologically interesting areas on titan we investigate the nature and possible formation processes of three areas on titan s surface which have been suggested as geologically interesting hotei regio tui regio and sotra patera we also reanalyze the spectral characteristics of the huygens landing site we apply a statistical principal component analysis pca and a radiative transfer rt method on the visual and infrared mapping spectrometer datacubes in order to retrieve the surface albedo of distinct spectral units in the near infrared we have been able to exploit only a subset of the currently available hotei regio data which are in general not optimal in terms of geometry for an analysis with a plane parallel rt code our inferred surface albedos present generally higher values from 1 to 2 m and lower ones at 0 94 and in the 2 6 5 m region the regions of interest rois within hotei regio tui regio and sotra patera are always significantly brighter than the surrounding areas the largest variations are found longward of 2 m and mainly at 5 m this higher surface albedo with respect to the surrounding area and in general the fact that the spectral behavior is different for each of these areas is probably indicative of diverse chemical compositions and origins we compare the spectral albedos with some suggested surface candidates on titan such as h2o co2 and ch4 ices as well as tholin and discuss possible chemical composition variations as well as other interpretations

modelling landscape evolution in the waipaoa catchment new zealand a phenomenalogical approach landscape evolution models require detailed strength measurements which are difficult to obtain for large areas we offer an alternative phenomenalogical approach to modelling landscape evolution one that requires few input parameters the phenomena are hills channels floodplains knickpoints and coastal floodplain the model is demonstrated on the highly erodible waipaoa catchment in new zealand a digital elevation model is simulated every thousand years from 63000 bp through to present day there is good agreement between predicted and observed terrace heights and also good agreement between predicted and observed knickpoint locations suggesting the phenomenalogical approach is indeed representing the main drivers of landscape evolution in the waipaoa catchment

seismic response analysis of the deep saturated soil deposits in shanghai the quaternary deposits in shanghai are horizontal soil layers of thickness up to about 280m in the urban area with an annual groundwater table between 0 5 and 0 7m from the surface the characteristics of deep saturated deposits may have important influences upon seismic response of the ground in shanghai based on the biot theory for porous media the water saturated soil deposits are modeled as a two phase porous system consisting of solid and fluid phases in this paper a nonlinear constitutive model for predicting the seismic response of the ground is developed to describe the dynamic characters of the deep saturated soil deposits in shanghai subsequently the seismic response of a typical site with 280m deep soil layers which is subjected to four base excitations el centro taft sunan and tangshan earthquakes is analyzed in terms of an effective stress based finite element method with the proposed constitutive model special emphasis is given to the computed results of accelerations excess pore water pressures and settlements during the seismic excitations it has been found that the analysis can capture fundamental aspects of the ground response and produce preliminary results for seismic assessment

a rigid and weathered ice shell on titan a strong inverse correlation between gravity and topography leads to the conclusion that saturn s largest moon titan must have a rigid ice shell with an elastic thickness exceeding 40 kilometres titan saturn s largest moon may have a stronger ice shell than previously thought several lines of evidence suggest that titan has a global subsurface ocean beneath an outer ice shell 50 200 km thick with a rigid portion that is thin and weak here hemingway et al report a strong inverse correlation between gravity and topography at long wavelengths that are not dominated by tides and rotation this finding is not compatible with a geologically active low rigidity ice shell suggesting that titan s ice shell must be substantially rigid with an elastic thickness of greater than 40 km several lines of evidence suggest that saturn s largest moon titan has a global subsurface ocean beneath an outer ice shell 50 to 200 kilometres thick1 2 3 4 if convection5 6 is occurring the rigid portion of the shell is expected to be thin similarly a weak isostatically compensated shell has been proposed7 8 to explain the observed topography here we report a strong inverse correlation between gravity3 and topography9 at long wavelengths that are not dominated by tides and rotation we argue that negative gravity anomalies mass deficits produced by crustal thickening at the base of the ice shell overwhelm positive gravity anomalies mass excesses produced by the small surface topography giving rise to this inverse correlation we show that this situation requires a substantially rigid ice shell with an elastic thickness exceeding 40 kilometres and hundreds of metres of surface erosion and deposition consistent with recent estimates from local features10 11 our results are therefore not compatible with a geologically active low rigidity ice shell after extrapolating to wavelengths that are controlled by tides and rotation we suggest that titan s moment of inertia may be even higher that is titan may be even less centrally condensed than is currently thought12

sequential stage development of crescentic bars hahoterim beach southeastern mediterranean abstract sequential bar development involving in order multiple bars ridge and runnels transverse oblique bars and meandering or crescentic shore attached or detached bars of both outer and nested inner systems were delineated at hahoterim beach northern israel the concomitant wave data including wave directions energy spectrum significant wave height and length of the calm period showed strong correlation with the bar stages there is a notable lack of correlation between bar stages and incident wave periods which were quite variable even on a daily basis two bar developmental sequences were delineated one shore normal and the other initially oblique but gradually rotating to shore normal in the mature stage threshold conditions for the initial stage development of shore normal crescentic systems were defined as h1 3 1 0 m peak spectral density of 1 m2 hz and swell directions within 7 from the normal the outer crescentic systems formed within 1 to 2 weeks the nested inner crescentic bar system formed under different wave conditions development of inner micro cresentic bars required 3 to 7 weeks of calm waves h1 3 0 3 m except for a short initiating pulse of wave energy from waves of about i m in height the double crescentic pattern indicates the optimal evolutiona y stage of crescentic systems the residence time of bar types was determined by the frequency of crossing of these threshold conditions the outer bars and the mega rip channels composed the most stable inshore elements out of phase relationships between inner and outer bar systems resulted from the lag in response of the outer bars behind changes in wave direction among the inner crescentic bars and shore rhythms phase correlation was the was the rule regional aerial photography and wave data indicate that the bar wave relationships at hahoterim axe representative of the eastern flank of the nile including most of the israeli coast although the bar types described from other coasts are similar to those mapped at hahoterim and the threshold wave conditions for initiation of bar stage development appear to be similar the frequency of occurrence of specific bar types appears to be different at hahoterim

cryovolcanic features on titan s surface as revealed by the cassini titan radar mapper abstract the cassini titan radar mapper obtained synthetic aperture radar images of titan s surface during four fly bys during the mission s first year these images show that titan s surface is very complex geologically showing evidence of major planetary geologic processes including cryovolcanism this paper discusses the variety of cryovolcanic features identified from sar images their possible origin and their geologic context the features which we identify as cryovolcanic in origin include a large 180 km diameter volcanic construct dome or shield several extensive flows and three calderas which appear to be the source of flows the composition of the cryomagma on titan is still unknown but constraints on rheological properties can be estimated using flow thickness rheological properties of one flow were estimated and appear inconsistent with ammonia water slurries and possibly more consistent with ammonia water methanol slurries the extent of cryovolcanism on titan is still not known as only a small fraction of the surface has been imaged at sufficient resolution energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of titan

short term changes in the morphodynamic states of beaches and surf zones an empirical predictive model a time series of 6 5 years of daily observations of beach states and wave characteristics from southeastern australia was analyzed with the aim of determining the degree to which time varying beach state can be explained and predicted the six commonly occurring beach states dissipative longshore bar trough rhythmic bar and beach transverse bar and rip low tide terrace and reflective discussed earlier were related by means of discrete discriminant analyses to the parameter hb wst where hb is breaker height ws is the fall velocity of the beach sand and t is peak breaker period using a total of 1545 cases two values were used in the analyses the immediate value occurring on the day the particular state was observed and a weighted mean value expressing recently antecedent conditions the immediate value made a negligible contribution to explaining day to day beach state observations however the antecedent conditions showed a strong relationship and provide a successful means of prediction by examining cases where the time derivatives of both state and were near zero it was possible to define the equilibrium conditions associated with each state directions of change erosional or accretionary are predicted in terms of departures of from the equilibrium value appropriate to the beach state prevailing at the time change begins