3d seismic study of a shale expulsion syncline at the base of the champion delta offshore brunei and its implications for the early structural evolution of large delta systems an example of a late miocene expulsion rollover syncline related to mobile shale is described from 3d seismic data offshore brunei prodelta shales accumulated in the subsiding syncline were altered after deep burial by overpressure increase and hydraulic fracturing consequently seismic facies was modified from a continuous divergent reflection pattern to a low amplitude disrupted to chaotic seismic facies bounded by a high amplitude event that cross cuts original stratification without the resolution provided by 3d data the high amplitude event would be mistaken for early growth faults and the subdued country rock reflections for mobile shale typical features at the base of large deltas this study shows the existence of expulsion rollovers related to mobile shale which have not been described before and demonstrates that not all bright reflections at chaotic coherent facies boundaries are actually fault planes it also suggests that expulsion synclines even during early phases of delta development may be compaction related features rather than ones that drive the shale mass out of the area of progradation

towards a protocol for laser scanning in fluvial geomorphology advances in spatial analytical software allow digital elevation models dems to be produced which accurately represent landform surface variability and offer an important opportunity to measure and monitor morphological change and sediment transfer across a variety of spatial scales many of the techniques presently employed aerial lidar edm theodolites gps photogrammetry suffer coverage or resolution limitations resulting in a trade off between spatial coverage and morphologic detail captured this issue is particularly important when rates of spatial and temporal change are considered for fluvial systems this paper describes the field and processing techniques required for oblique laser scanning to acquire 0 01 m resolution digital elevation data of an upland reach of the river wharfe in the uk the study site is variable with rapidly changing morphology diverse vegetation and the presence of water and these are evaluated with respect to laser data accuracy scan location frequency and distance are discussed with reference to survey accuracy and efficiency and a field protocol is proposed scan data cloud merging was achieved with a high degree of precision sub centimetre and positional data are shown to be very accurate for exposed surfaces vegetation and water decrease the accuracy as the laser pulse is often prevented from reaching the ground surface or is not returned copyright 2006 john wiley sons ltd

high resolution seismic imaging in deep sea from a joint deep towed obh reflection experiment application to a mass transport complex offshore nigeria we assess the feasibility of high resolution seismic depth imaging in deep water based on a new geophysical approach involving the joint use of a deep towed seismic device sysif and ocean bottom hydrophones obhs source signature measurement enables signature deconvolution to be used to improve the vertical resolution and signal to noise ratio the source signature was also used to precisely determine direct traveltimes that were inverted to relocate source and receiver positions the very high accuracy of the positioning that was obtained enabled depth imaging and a stack of the obh data to be performed the determination of the p wave velocity distribution was realized by the adaptation of an iterative focusing approach to the specific acquisition geometry this innovative experiment combined with advanced processing succeeded in reaching lateral and vertical resolution 2 5 and 1 m in accordance with the objectives of imaging fine scale structures and correlation with in situ measurements to illustrate the technological and processing advances of the approach we present a first application performed during the erig3d cruise offshore nigeria with the seismic data acquired over ng1 a buried mass transport complex mtc interpreted as a debris flow by conventional data evidence for a slide nature of a part of the mtc was provided by the high resolution of the obh depth images rigid behaviour may be inferred from movement of coherent material inside the mtc and thrust structures at the base of the mtc furthermore a silt layer that was disrupted during emplacement but has maintained its stratigraphic position supports a short transport distance

tectono sedimentary analysis of a complex extensional neogene basin formed on thrust faulted northern apennines hinterland radicofani basin italy abstract large nw se oriented neogene quaternary structural depressions up to about 200 km long and 25 km wide have developed on the western side hinterland of the northern apennines over thrust substrate the depressions are now for the most part laterally bounded by normal faults and are longitudinally separated into basins by transfer zones a debate exists in the literature as to whether these basins have developed as half graben under a predominantly extensional regime since late miocene or as thrust top basins under a predominantly compressional regime that has continued until the pleistocene the radicofani basin is one of the best preserved basins it developed mainly during the late miocene early pliocene in the southern half of the siena radicofani structural depression and is now bounded on the east by normal faults that transect a thrust anticline nose in the substrate to the north by a substrate high or transfer zone and to the south and west by quaternary igneous volcanic edifices the basin experienced variable differential tectonic and associated sedimentation along linking normal boundary faults along its eastern margin it shows the development of thick 600 m alluvial fans that developed in relay areas between boundary faults and transverse faults and transfer zones well exposed sections generally show upward transitions from conglomeratic alluvial fans to shoreface sandstone to offshore mudstones locally the transition is marked by deltas primarily characterised by thick gravelly sandy stacked cross sets the thicker sandy gravel to gravelly sand cross sets 5 8 m thick are interpreted as gilbert type deltas interstratified thinner 0 5 1 m thick generally openwork gravelly strata are part of delta topset assemblages and probably represent prograding fluvial bars tectonic movements provided the accommodation space for the total 2700 m thick basin fill sea level fluctuations that led to the repeated development of the cross sets may also have been influenced by climatic or eustatic changes possibly related to the effects of early antarctic glaciations some features of the radicofani basin can be found in both extensional and compressional basins however the position of the basin in the mountain chain and the development of alluvial fans fandeltas and associated deposits along the main boundary fault combined with structural evidence from seismic lines show that during the early pliocene this basin best conforms to existing models of half graben

why does salt start to move abstract this paper concerns mechanisms of salt and ductile shale movement it investigates salt flow due to differential loading folding of the overburden during compression and drag by a moving overburden the approach is to compare the salt flux caused by these processes to that generated by buoyancy it is demonstrated that overburden folding and drag by the overburden can under commonly encountered conditions result in greater amounts of salt movement than that produced by buoyancy or differential loading these conclusions apply during the early stages of salt anticline salt pillow and salt roller formation but not during the later stages of salt diapir and salt wall growth when buoyancy dominates the quantitative significance of these alternatives to buoyancy is determined by considering an elastic plate overlying a viscous fluid this is the simplest mathematical model that can reproduce the processes considered the model shows that 1 under certain conditions these mechanisms produce more salt movement than buoyancy differential loading dominates when the surface slopes become more than a small fraction of the slope of the salt top overburden buckling dominates if the in plane stress exceeds a critical value drag dominates when the salt layer is thinner than a few hundred metres 2 the strength of the overburden inhibits formation of salt diapirs even those due to buoyancy on wavelengths less than about 12 km

objective landslide detection and surface morphology mapping using high resolution airborne laser altimetry a map of extant slope failures is the most basic element of any landslide assessment without an accurate inventory of slope instability it is not possible to analyze the controls on the spatial and temporal patterns of mass movement or the environmental human or geomorphic consequences of slides landslide inventory maps are tedious to compile difficult to make in vegetated terrain using conventional techniques and tend to be subjective in addition most landslide inventories simply outline landslide boundaries and do not offer information about landslide mechanics as manifested by internal deformation features in an alternative approach we constructed accurate high resolution dems from airborne laser altimetry lidar data to characterize a large landslide complex and surrounding terrain near christchurch new zealand one dimensional circular 2 d and spherical 3 d statistics are used to map the local topographic roughness in the dems over a spatial scale of 1 5 to 10 m the bedrock landslide is rougher than adjacent unfailed terrain and any of the statistics can be employed to automatically detect and map the overall slide complex furthermore statistics that include a measure of the local variability of aspect successfully delineate four kinematic units within the gently sloping lower half of the slide features with a minimum size of surface folds that have a wavelength of about 11 to 12 m and amplitude of about 1 m are readily mapped two adjacent earthflows within the landslide complex are distinguished by a contrast in median roughness and texture and continuity of roughness elements the less active of the earthflows has a surface morphology that presumably has been smoothed by surface processes the laplacian operator also accurately maps the kinematic units and the folds and longitudinal levees within and at the margins of the units finally two dimensional power spectra analyses are used to quantify how roughness varies with length scale these results indicate that no dominant length scale of roughness exists for smooth unfailed terrain in contrast zones with different styles of landslide deformation exhibit distinctive spectral peaks that correspond to the scale of deformation features such as the compression folds the topographic based analyses described here may be used to objectively delineate landslide features generate mechanical inferences about landslide behavior and evaluate relatively the recent activity of slides published by elsevier science b v

displacement fields from point cloud data application of particle imaging velocimetry to landslide geodesy 1 acquiring spatially continuous ground surface displacement fields from terrestrial laser scanners tls will allow better understanding of the physical processes governing landslide motion at detailed spatial and temporal scales problems arise however when estimating continuous displacement fields from tls point clouds because reflecting points from sequential scans of moving ground are not defined uniquely thus repeat tls surveys typically do not track individual reflectors here we implemented the cross correlation based particle image velocimetry piv method to derive a surface deformation field using tls point cloud data we estimated associated errors using the shape of the cross correlation function and tested the method s performance with synthetic displacements applied to a tls point cloud we applied the method to the toe of the episodically active cleveland corral landslide in northern california using tls data acquired in june 2005 january 2007 and january may 2010 estimated displacements ranged from decimeters to several meters and they agreed well with independent measurements at better than 9 root mean squared rms error for each of the time periods the method provided a smooth nearly continuous displacement field that coincides with independently mapped boundaries of the slide and permits further kinematic and mechanical inference for the 2010 data set for instance the piv derived displacement field identified a diffuse zone of displacement that preceded by over a month the development of a new lateral shear zone additionally the upslope and downslope displacement gradients delineated by the dense piv field elucidated the non rigid behavior of the slide

stabilization by geomorphic reclamation of a rotational landslide in an abandoned mine next to the alto tajo natural park abstract two abandoned kaolin mines surrounding one of the most outstanding natural parks of spain the alto tajo have caused frequent environmental impacts within these are unstable areas prone to extensive mass movements that influence off site sediment dynamics over the fluvial system a waste dump in the nuria mine obstructing a stream in the center of a valley experienced a rotational landslide mass movement between 2012 and 2014 was 0 025 0 026 m day 1 to mitigate the high risk of an earthflow a novel stabilizing surface drainage technique was implemented two remedial valleys designed with fluvial channels were constructed surrounding the landslide main body using natural landform design and regrading with no need for artificial materials such as concrete or piles this novel remediation process is generically termed geomorphic reclamation the specific method applied to this site was geofluv with natural regrade software before 2014 and after geomorphic stabilization 2015 2017 the landslide was monitored using digital elevation models dems of difference dods obtained by a geomorphic change detection gcd tool two modern techniques terrestrial laser scanning tls and structure from motion photogrammetry combined with an unmanned aerial vehicle sfm uav were used to acquire high resolution topographies hrts from which dems were derived data analysis and field monitoring results demonstrate that i the nuria mine transformed almost 50 of the upper part of a natural catchment ii a waste dump active landslide with a surface rupture

kinematic analysis of faults in a physical model of growth faulting above a viscous salt analogue abstract syn sedimentary faults overlying an extended ductile layer within a sand model provide an analogue for studying some aspects of the geometry and kinematics of basin scale extensional listric faults associated with salt rollers the displacement analysis techniques used to examine displacement variations over fault surfaces within the sand model show that displacement varies in a regular and predictable manner deviations from simple fault displacement patterns are due to transfers of displacement onto adjacent synthetic faults aggregation of the displacements on adjacent synthetic faults produces more regular patterns of displacement distribution and demonstrates the geometric coherence of the aggregated faults rapid upward decreases in displacement on the model faults are due to fault growth during sedimentation elsewhere in the model post sedimentary faulting is associated with very low upward displacement gradients and pre and syn faulting sedimentation are readily distinguished on cross sectional fault traces in three dimensions a non horizontal line separating the pre faulting and syn faulting sequences tracks the lateral extent of a fault through time backstripping of fault displacements by subtracting the fault displacement of a sedimentary horizon from the displacements of underlying horizons gives the displacement distribution on a fault surface at the time of deposition of the backstripped horizon backstripped fault displacement distributions also allow examination of the general fault structure through time backstripping of fault displacements on one of the larger faults within the model and on an associated hanging wall synthetic splay shows that the two structures originated as a relay zone which was breached by lateral propagation of one of the overlapping faults which form the relay zone the backstripping technique allows determination of the geometrical changes during growth of a fault system

raft tectonics the effects of basal slope angle and sedimentation rate on progressive extension abstract in the gulf of guinea the upper cretaceous tertiary sedimentary cover has undergone gravity gliding above an aptian salt layer for various basal slope angles from 0 to 4 gliding started during albian time and evolved up to the present with variable sedimentation rates faulting patterns are seen to vary in particular as a function of the basal slope angle and the syn kinematic sedimentation rates a series of laboratory experiments on small scale models is used to study the effects of the two parameters mentioned above models are composed of two layer slabs with newtonian silicone putty at the base to represent a basal salt decollement and dry sand on top to represent the sedimentary overburden models are allowed to deform under their own weight for various basal slope angles ranging from 0 to 5 with two different syn kinematic sedimentation rates it is shown that the basal slope angle controls the location of faulting in the overburden within a single downslope deformation domain for values smaller than 2 and within two domains lying downslope and upslope for higher values of the width of the deformation domains also varies as a function of overburden faulting always starts with syn kinematic grabens which evolve into symmetric or asymmetric grabens or into tilted blocks bounded by listric normal faults while synthetic listric normal faults characterize the downslope deformation domains both synthetic and antithetic listric normal faults can occur in the upslope deformation domain ductile deformation within the basal decollement layers results from variable combinations of pure shear and simple shear interaction of ductile deformation in the ductile decollement layer with faulting in the overburden locally produces complex and heterogeneous strain patterns notably within salt rollers finally increasing rates of syn kinematic sedimentation are seen to increase the rate of downslope displacement and to enhance and favour the development of listric normal faults

multitemporal alsm change detection sediment delivery and process mapping at an active earthflow remote mapping and measurement of surface processes at high spatial resolution is among the frontiers in earth surface process research remote measurements that allow meter scale mapping of landforms and quantification of landscape change can revolutionize the study of landscape evolution on human timescales at mill gulch in northern california usa an active earthflow was surveyed in 2003 and 2007 by airborne laser swath mapping alsm enabling meter scale quantification of landscape change we calculate four year volumetric flux from the earthflow and compare it to long term catchment average erosion rates from cosmogenic radionuclide inventories from adjacent watersheds we also present detailed maps of changing features on the earthflow from which we can derive velocity estimates and infer dominant process these measurements rely on proper digital elevation model dem generation and a simple surface matching technique to align the multitemporal data in a manner that eliminates systematic error in either dataset the mean surface elevation of the earthflow and an opposite slope that was directly influenced by the earthflow decreased 14 1 mm yr from 2003 to 2007 by making the conservative assumption that these features were the dominant contributor of sediment flux from the entire mill gulch drainage basin during this time interval we calculate a minimum catchment averaged erosion rate of 0 30 0 02 mm yr analysis of beryllium 10 10be concentrations in fluvial sand from nearby russian gulch and the south fork gualala river provide catchment averaged erosion rates of 0 21 0 04 and 0 23 0 03 mm yr respectively from translated landscape features we can infer surface velocities ranging from 0 5 m yr in the wide upper source portion of the flow to 5 m yr in the narrow middle transport portion of the flow this study re affirms the importance of mass wasting processes in the sediment budgets of uplifting weak lithologies copyright 2011 john wiley sons ltd

airborne lidar in support of geomorphological and hydraulic modelling this paper considers the application of airborne laser altimetry lidar to the provision of elevation data at accuracies and spatial densities commensurate with the current generation of high resolution hydraulic models three sets of issues are addressed with reference to a telemac 2d model of a morphologically complex estuary in eastern england first the quality of airborne lidar data is assessed via multiscale calibration against surveyed sections and supplementary control points second image processing techniques are used for i identification of multiple regions of interest within large lidar mosaics ii subregional infilling of voids left by data drop outs iii filtering and subsampling to match topographic information content with model resolution and the density of the computational mesh third the implications of improved terrain data are considered with reference to the estimation of elevations and potential tidal volumes for a number of discrete flood compartments and the modelling of hypothetical inundation scenarios after minor offset correction to ensure registration with local benchmarks the quality of lidar elevation data within a 12 km x 4 kin coverage is found to be consistent with the published specification 0 10 to 0 15 m image processing tools provide an efficient means of managing information content and interfacing this with the gis based functionality of the preprocessing software used in conjunction with the hydraulic model the accuracy and spatial resolution of the lidar data allow the identification of subtle but important topographic variations between adjacent flood compartments in many cases differences in model results obtained using these data relative to previously estimated average flood compartment elevations are small importantly however lidar provides topographic information at an accuracy and resolution close to the present limits of model representation reliable representation of form allows the modeller to concentrate on the physical aspects of model parameterization whilst minimizing the conflation of parameter effects with those of poorly constrained geometric representation copyright c 2003 john wiley sons ltd

effects of land use changes on badland erosion in clayey drainage basins radicofani central italy abstract hillslopes of the radicofani area in the upper valley of the orcia river southern tuscany region italy consist mainly of early pliocene clayey sediments and are widely affected by frequent badland erosion reforestation with frugal conifers has been carried out in the area over the last 50 years the goal of the present study is to evaluate the impact of reforestation and land use change on erosion rates in nine small drainage basins through a multidisciplinary approach geological geomorphological hydrological and land use characteristics were analyzed by a diachronic confrontation between pre reforestation 1954 and post reforestation 2007 situations aerial photo interpretation and processing in gis allowed us to quantify changes in areas affected by badland erosion land use and variations in erosion rates moreover dendrometric data were gathered from 18 circular sample plots in forest stands of 40 years old this allowed us to evaluate both the adaptability of different forest species to the clayey substrate and reforestation fragmentation the differences between the pre and post reforestation situations led to increases in arable land and forest areas and considerable decreases in erosion rates and badland areas however no significant correlation between the erosion rates and the forest area emerged due to the excessive fragmentation of reforestation cores and relatively small reforested surfaces land reclamation seems to have played a more important role in reducing erosion in the clayey substrate the integrated method presented here is an important tool useful to understand the morphological dynamics of badlands in relation to forest vegetation and for land planning and management

tracking and evolution of complex active landslides by multi temporal airborne lidar data the montaguto landslide southern italy abstract a multi temporal lidar study of an active landslide at montaguto italy is presented four lidar derived digital terrain models acquired on may 2006 july 2009 april 2010 and june 2010 are used the interpretation of selected morphometric parameters surface roughness residual topographic surface and the statistical analysis of the temporal variations of such parameters allowed the reconstruction and tracking of the landslide the landslide boundary monitoring was achieved and zones of uplift and subsidence volumes of removed and or accumulated material and average rates of vertical and horizontal displacement retreat rate of the crown and advancement rate of the toe were estimated deformation structures scarps cracks folds affecting the landslide in different times were also mapped some of such structures represent precursors of impending instability processes or give information on the mechanism of emplacement various types of activity e g rock fall flow and geometry e g channelized flow are recognized and zones whose topographic features change with time due to artificial drainage and earth handling removal work were detected the lidar derived information allows us to decipher the kinematics of the landslide the results provide new insight on the use of airborne lidar in the monitoring strategies of gravity controlled processes

estimating volume of deep seated landslides and mass transport in basihlan river basin taiwan abstract deep seated landslides are often caused by severe rainfall but the displaced potential landslide mass often does not slide downslope entirely in one time evaluation of the mobilized volume of the deep seated landslide and the volume of the remaining potentially unstable landslide mass on the slope is vital for hazard mitigation in this study an integrated method was developed for evaluation of the potential landslide volume and mass transport of deep seated landslides caused by typhoon morakot in basihlan river basin taiwan a combination of various types of remote sensing data including aerial photographs satellite images and light detection and ranging lidar data from before and after the event were used for locating landslides and the deep seated landslides were identified in the basihlan river basin liuoguey district kaohsiung city taiwan a stability analysis and a profile analysis were conducted to determine the critical sliding surface of each deep seated landslide and the volumes masses of the landslides were estimated the total volume of all the deep seated landslides was approximately 6 017 000 m3 in the basihlan river basin a topographic analysis was performed to evaluate the mass transport of the deep seated landslides using lidar derived digital terrain models dtms before and after typhoon morakot the mass transport of deep seated landslides in the basihlan river basin was determined to be approximately 3 527 300 m3 which suggested the volume of the remaining potentially unstable landslide mass on slope of approximately 41 4 the available field data suggested subsequent reactivations of the deep seated landslides after typhoon morakot including debris flow generation which damaged the infrastructure thus a large landslide volume remaining in the basihlan river basin can cause more landslides or debris flow hazards in the future estimation of the potential landslide volume and mass volume remaining on slopes is essential for both short and long term mitigation strategies

sedimentation and shale tectonics of the northwestern niger delta front abstract the modern day slope and outer shelf of the niger delta are characterized by fault bounded sedimentary depocentres and intervening shale structures some of which are diapiric using two dimensional seismic reflection data and stratigraphic information from five wells the neogene history of a 70 30 km portion of the northwestern niger delta shelf and slope has been examined the shale structures were established by late miocene time probably in response to lateral shale withdrawal from beneath the advancing deltaic load combined with compressional uplift and folding of pro delta strata during pliocene and pleistocene time these structures were buried by the prograding delta and extensional growth faulting commenced stacked onlap relationships and stacked erosional channels indicate that the shale structures continued to influence sedimentation patterns throughout this period throughout the pliocene extension and subsidence were concentrated in a graben like depocentre bounded by both regional and counter regional growth faults during the early pleistocene subsidence on the regional growth fault ceased and growth was transferred to the counter regional growth fault set the geometry and history of the depocentre is analogous to salt related depocentres typical of the northern gulf of mexico and atlantic margins of brazil and angola to explain the history of the niger delta study area a model is proposed in which the miocene pleistocene sedimentary package has slid basinward breaking up during extension thereby creating seaward stepping depocentres examples from analogue modelling studies are used to suggest possible origins for the large counter regional growth faults

spatial characterization resolution and volumetric change of coastal dunes using airborne lidar cape hatteras north carolina the technological advancement in topographic mapping known as airborne light detection and ranging lidar allows researchers to gather highly accurate and densely sampled coastal elevation data at a rapid rate the problem is to determine the optimal resolutions at which to represent coastal dunes for volumetric change analysis this study uses digital elevation models dem generated from lidar data and spatial statistics to better understand dune characterization at a series of spatial resolutions the lidar data were collected jointly by the national aeronautics and space administration nasa the national oceanic and atmospheric administration noaa and the u s geological survey usgs dems of two study sites 100 200 m located in cape hatteras national seashore north carolina were generated using a raster based geographic information system gis changes in the dune volume were calculated for a 1 year period of time fall 1996 1997 at grid cell resolutions ranging from 1 1 to 20 20 m directional statistics algorithms were used to calculate local variance and characterize topographic complexity data processing was described in detail in order to provide an introduction to working with lidar data in a gis results from these study sites indicated that a 1 2 m resolution provided the most reliable representation of coastal dunes on cape hatteras and most accurate volumetric change measurements results may vary at other sites and at different spatial extents but the methods developed here can be applied to other locations to determine the optimum resolutions at which to represent and characterize topography using common gis and database software

application of a multi temporal lidar derived digital terrain model in a landslide volume estimation sediments produced by landslides are crucial in the sediment yield of a catchment debris flow forecasting and related hazard assessment on a regional scale however it is difficult and time consuming to measure the volumes of such sediment this paper uses a lidar derived digital terrain model dtm taken in 2005 and 2010 at 2 m resolution to accurately obtain landslide induced sediment volumes that resulted from a single catastrophic typhoon event in a heavily forested mountainous area of taiwan the landslides induced by typhoon morakot are mapped by comparison of 25 cm resolution aerial photographs taken before and after the typhoon in an 83 6 km2 study area each landslide volume is calculated by subtraction of the 2005 dtm from the 2010 dtm and the scaling relationship between landslide area and its volume are further regressed the relationship between volume and area are also determined for all the disturbed areas vl 0 452al1 242 and for the crown areas of the landslides vl 2 510al1 206 the uncertainty in estimated volume caused by use of the lidar dtms is discussed and the error in absolute volume estimation for landslides with an area 105 m2 is within 20 the volume area relationship obtained in this study is also validated in 11 small to medium sized catchments located outside the study area and there is good agreement between the calculation from dtms and the regression formula by comparison of debris volumes estimated in this study with previous work it is found that a wider volume variation exists that is directly proportional to the landslide area especially under a higher scaling exponent copyright 2013 john wiley sons ltd

kinematics of active earthflows revealed by digital image correlation and dem subtraction techniques applied to multi temporal lidar data earthflow type landslides are persistent natural hazards having deep socio economic and environmental consequences they have significantly contributed to the geomorphic evolution of mountainous slopes in europe since the late glacial an understanding of their complex kinematics is crucial to better constrain the processes governing their occurrence and mobility in this work we explored the possibility to quantify displacement vectors on a spatially distributed basis and to quantify volumetric transfer at the slope scale with regard to a large flow type landslide located in the northern apennines of italy for this purpose we applied digital image correlation dic and digital elevation model differencing demod techniques to multi temporal airborne lidar surveys of 2006 2007 and 2009 the dic was applied to greyscale slope gradient maps retrieved after precise co registration of lidar surveys thereby movement patterns over various sectors of the landslide were reconstructed and quantified most notably up to 20 m in the head zone up to 51 m in the lower main track and up to about 27 m at the landslide toe the demod analysis revealed significant mass transfer from the source to the tracks and toe zone with the upper flow tracks acting as temporal storage of large amounts of material the mass balance indicated that significant amounts of advancing landslide debris were eroded by a local stream an integrated analysis of demod and dic results allowed for a discussion of governing processes such as the transition from slide to flow the influence of underlying topography on earthflow mobility and the role of undrained loading as a mechanism of toe zone reactivation in conclusion the successful application of dic and demod to the case study underlines the added value of high resolution dems in the analysis of earthflow kinematics toward a better understanding of their role in the geomorphic evolution of slopes copyright 2012 john wiley sons ltd

runout analysis of a large rockfall in the dolomites italian alps using lidar derived particle sizes and shapes lidar data were used to quantify and analyse a rockfall event which occurred in 2003 in the western dolomites italian alps in addition to previously existing airborne laserscanning als data high resolution terrestrial laserscanning tls data were collected by using the original point clouds the volume axial ratio and runout length of single boulders as well as the surface roughness in the runout zone of the rockfall were derived the total volume of the rockfall event of approximately 10 000 m was estimated by a reconstruction of the pre event surface at the detachment zone the analysis of the laser scanning data of the accumulation zone revealed a power law scaling for boulder volumes larger than 8 m the dependence of runout length on boulder volume is complex it is moderated by particle sphericity in addition we used als and tls data to derive the spatial distribution of surface roughness on the talus cone tls allow for more accurate roughness mapping than als data but for most applications the point density of als data seems to be sufficiently high to derive measures of roughness different sampling approaches for plane fitting on the scale of 5 m did not show significant effects besides the computational time the results of our analyses provide important perspectives for rockfall modelling and process understanding with potential applications in both applied natural hazards and pure geomorphological research copyright 2012 john wiley sons ltd

lidar monitoring of mass wasting processes the radicofani landslide province of siena central italy abstract the radicofani basin stretching about 30 km nw se is an intra central apennine basin connected to pliocene pleistocene extensional tectonics it consists of an early to middle pliocene succession including essentially shelf pelites in the radicofani area province of siena tuscany region morphodynamic processes are very frequent with widespread badlands and rapidly evolving mudflows in order to evaluate the general instability of the radicofani area geological and geomorphological surveys were carried out the 1954 1990 and 2003 aerial surveys allowed a comparison of the changes in the various morphological aspects of the study area which suggested an increase in slope instability with time a new complex translational landslide evolving into mudflows activated during the winter of 2003 was monitored using an experimental system based on terrestrial lidar light detection and ranging and gps global positioning system technologies this system allowed the monitoring of the morphologic and volumetric evolution of the landslide a comparison of the monitoring data of october 2004 june 2005 may 2006 and may 2007 points out that the evolution is characterised by the sliding of displaced materials a volume of about 1300 m 3 of materials was removed during the period 2004 2005 300 m 3 for 2005 2006 and 400 m 3 for 2006 2007 the greater initial mass movement probably reflects a greater static imbalance during the early period of landslide movement and increased rainfall therefore the proposed monitoring system methodology allows the numerical evaluation of the landslide morphological evolution and to validate the landslide evolution model based on geological and geomorphological field surveys

digital photogrammetric analysis and electrical resistivity tomography for investigating the picerno landslide basilicata region southern italy abstract digital photogrammetric analysis and electrical resistivity tomography ert techniques were applied to evaluate the volume of material involved in a complex roto translational slide occurred in the territory of picerno basilicata region southern italy analytical and digital photogrammetric techniques facilitated a multi temporal analysis of aerial photos for the years 1997 2004 and 2006 in order to identify different geomorphologic features scarps terraces and trenches of the landslide and their development the analytical and digital photo interpretation was performed at the maximum scale of 1 5000 geological and geomorphological surveys were carried out to verify photo interpretation results digital elevation models dems for 1997 2004 and 2006 were produced by applying the grid adaptive method the differential dems 2006 1997 2006 2004 2004 1997 for the most dangerous part of the landslide allowed us to recognize the areas affected either by deposition or erosion and also estimate any altitudinal changes in each geomorphologic unit to detect the sliding surface and estimate the thickness of the sliding material several transversal and longitudinal ert profiles were obtained the electrical images of subsurface supported by stratigraphical data from boreholes were integrated with the information from the dems the altitudinal changes and the sizes of the source and accumulation areas allowed us to estimate the volume of material involved in the mass movement the fusion of data from different sensors allows us to gather indications on the surface and subsurface characteristics of the landslide providing useful information for landslide mitigation activities such an approach can help both to improve our knowledge and overcome the drawbacks of each methodology

rheological and tectonic modeling of salt provinces abstract technological improvements and a more rigorous research approach have led the petroleum industry to renew and expand its interest in physical modeling of faulting associated with halokinesis salt tectonics and the formation of structural hydrocarbon traps can be reproduced in models using viscous polymers for the substratum and frictional plastic granular materials for the overburden the fault patterns simulated in these dynamically scaled models are remarkably similar to those in depth converted seismic sections scale models are therefore useful for generating new concepts and for reconstructing the structural evolution of hydrocarbon traps although even unsealed models may help generating ideas the full transfer of quantitative data requires that models be dynamically scaled to their natural prototypes previously published scaling theory for salt tectonics has erroneously assumed fluid behaviour of the overburden this paper provides a sound scaling approach for geological deformations involving brittle overburdens on ductile substrata rheological data from overburden rocks and salt are compiled and compared to model rheologies using dimensions of laboratory analogs and other intrinsic material properties scaling approaches are compared and rules are formulated for achieving dynamic similarity in models of salt tectonics including those with synkinematic sedimentation

use of digital photogrammetry for the study of unstable slopes in urban areas case study of the el biar landslide algiers abstract recent developments in remote sensing techniques provide powerful tools for geomorphological studies the geometric and kinematic characterization of landslides is a key factor in understanding the mechanisms of movement the purpose of this publication is to show the potential of digital photogrammetry in the spatiotemporal study of landslides in urban areas the case study focuses on the landslide of el biar in algiers comparison of digital elevation models generated following an established methodology shows the morphological evolution of the site orthophotos are used to measure surface displacements the analysis of horizontal displacements between 1995 and 2007 shows that the landslide of el biar can be divided into two zones a peripheral zone moving at an average speed of about 5 cm per year and a central zone moving at an average speed of about 10 cm per year comparing the results with those obtained by traditional survey methods shows a remarkable consistency thus validating the techniques used this study demonstrates that digital photogrammetry when combined with geological and geotechnical data can improve the characterization and understanding of landslide mechanisms and thus help defining mitigation solutions

substrate deformation associated with the jocotitlan edifice collapse and debris avalanche deposit central mexico abstract an impressive debris avalanche deposit is preserved at jocotitlan volcano in central mexico the northern flank of this edifice collapsed 9690 years b p resulting in a 80 km 2 covering clast supported deposit that lacks substantial matrix fine weak or hydrothermally altered materials the deposit can be subdivided into three morphologically distinct areas which are each accompanied by specific and often unique deformation features in the underlying and adjacent volcaniclastic and lacustrine sediments from these features a complex history of pre and syn avalanche events was reconstructed beginning with edifice spreading on the weak substrate material prior to and in preparation of part of the flank collapse event the north eastern flank in particular was strongly coupled with the deforming substrate material as is still evident in its extensional profile and the unique mode of failure during the catastrophic event resulting in the deposition of what resembles non volcanic blockslide deposits rather than the typical hummocky volcanic debris avalanche morphology this latter type of failure occurred at the north western flank of jocotitlan volcano where few signs of substrate interactions are preserved in a deposit dominated by large conical hummocks in addition to substrate response interaction with pre avalanche topography in the eastern deposit area facilitated the emplacement of a lobe roughly perpendicular to the flank failure direction at apparent high emplacement velocity and with longitudinal ridges as its most striking surface expression

landslide inventory maps new tools for an old problem landslides are present in all continents and play an important role in the evolution of landscapes they also represent a serious hazard in many areas of the world despite their importance we estimate that landslide maps cover less than 1 of the slopes in the landmasses and systematic information on the type abundance and distribution of landslides is lacking preparing landslide maps is important to document the extent of landslide phenomena in a region to investigate the distribution types pattern recurrence and statistics of slope failures to determine landslide susceptibility hazard vulnerability and risk and to study the evolution of landscapes dominated by mass wasting processes conventional methods for the production of landslide maps rely chiefly on the visual interpretation of stereoscopic aerial photography aided by field surveys these methods are time consuming and resource intensive new and emerging techniques based on satellite airborne and terrestrial remote sensing technologies promise to facilitate the production of landslide maps reducing the time and resources required for their compilation and systematic update in this work we first outline the principles for landslide mapping and we review the conventional methods for the preparation of landslide maps including geomorphological event seasonal and multi temporal inventories next we examine recent and new technologies for landslide mapping considering i the exploitation of very high resolution digital elevation models to analyze surface morphology ii the visual interpretation and semi automatic analysis of different types of satellite images including panchromatic multispectral and synthetic aperture radar images and iii tools that facilitate landslide field mapping next we discuss the advantages and the limitations of the new remote sensing data and technology for the production of geomorphological event seasonal and multi temporal inventory maps we conclude by arguing that the new tools will help to improve the quality of landslide maps with positive effects on all derivative products and analyses including erosion studies and landscape modeling susceptibility and hazard assessments and risk evaluations

p and s velocity structure of the yellowstone volcanic field from local earthquake and controlled source tomography the three dimensional p and s velocity from vp vs ratios distribution and improved hypocenters for the yellowstone volcanic field have been determined from inversion of first arrival times from 7942 local earthquakes and 16 controlled source explosions the p velocity model has an rms residual of 0 09 s whereas the vp vs ratio model calculated from 511 earthquakes has an rms residual of 0 29 s high p and s velocities outside the yellowstone caldera represent thermally undisturbed basement and sedimentary rocks a caldera wide 15 decrease from regional p velocities at depths of 6 to 12 km is coincident with a 60 mgal gravity anomaly and is interpreted as a hot subsolidus granitic batholith with a quasi plastic rheology localized 30 reductions from regional seismic velocities and higher vp vs ratios 8 km beneath yellowstone s resurgent domes are interpreted as partial melts and vestigial magma systems associated with youthful less than 2 ma silicic volcanism additional low seismic velocities and vp vs ratios and a 20 mgal gravity low less than 4 km beneath the northeast caldera rim are interpreted as a hydrothermal fracture zone thermally driven by underlying partial melt hypocenters relocated with the three dimensional p velocity model show subparallel alignment with nw se trending postcaldera volcanic vents and normal faults northwest of the caldera focal depths of relocated earthquakes decrease from more than 11 km outside the caldera to less than 6 km within the caldera reflecting thinning and heating of the seismogenic crust

morphological and kinematic evolution of a large earthflow the montaguto landslide southern italy article ml ong earthflow in the southern apennines of italy following an analysis of th ed ifferent methods and techniques available to measure surface modifications caused by a large earthflow we selected a combination of monitoring techniques com patible with the montaguto case study we exploited i visual interpretation of aerial and satellite imagery ii quantitative analysis of six digital elevation model s dems covering the landslide area and iii al arge set of high accuracy three dimensional topographic measurements captured by three robotised total stations rtss in tegration of the results obtained from the different monitoring techniques allowed us to investigate the long multi decadal and short seasonal term evolution of the montaguto earthflow in the 58 year period 1954 2011 the examination of the available aerial satellit ea nd hill shade images revealed ac yclic long term behaviour of mass movements of different types in the rio nocelle catchment occupied by the recent montaguto earthflow the combined analysis of the six dems allowed measuring the material eroded from the landslide crown area v 1 4 10 6

long range terrestrial laser scanning for geomorphological change detection in alpine terrain handling uncertainties long range terrestrial laserscanning tls is an emerging method for the monitoring of alpine slopes in the vicinity of infrastructure nevertheless deformation monitoring of alpine natural terrain is difficult and gets even more challenging with larger scan distances in this study we present approaches for the handling of spatially variable measurement uncertainties in the context of geomorphological change detection using multi temporal data sets a robust distance measurement is developed which deals with surface roughness and areas of lower point densities the level of detection lod i e the threshold distinguishing between real surface change and data noise is based on a confidence interval considering the spatial variability of tls errors caused by large laser footprints low incidence angles and surface roughness spatially variable positional uncertainties are modelled for each point according to its range and the object geometry hit the local point cloud roughness is estimated in the distance calculation process from the variance of least squares fitted planes distance calculation and lod assessment are applied in two study areas in the eastern alps austria using multi temporal laserscanning data sets of slopes surrounding reservoir lakes at finstertal two tls point clouds of high alpine terrain and scanned from ranges between 300 and 1800 m are compared at gepatsch the comparison is done between an airborne laserscanning als and a tls point cloud of a vegetated mountain slope scanned from ranges between 600 and 3600 m although these data sets feature different conditions regarding the scan setup and the surface conditions the presented approach makes it possible to reliably analyse the geomorphological activity this includes the automatic detection of rock glacier movement rockfall and debris slides even in areas where a difference in vegetation cover could be observed this article is protected by copyright all rights reserved

review of earth science research using terrestrial laser scanning abstract the application of advanced remote sensing technologies including terrestrial laser scanning tls to the earth sciences has increased rapidly in the last two decades improving the spatial and temporal resolution of data terrestrial laser scanning units have evolved into a common tool in studies of spectral and structural geology seismology natural hazards geomorphology and glaciology special consideration of the advantages and limitations of tls in each of these fields is discussed in depth in the context of important work published in each field the workflow used in a tls survey is crucial to the success of the survey and field specific earth science workflows are therefore also discussed products based on tls data such as triangulated irregular networks tin and digital surface models dsm are commonplace tools throughout the earth sciences and the use of these tools to measure slip distributions fault geometries aeolian transport river bed morphologies and flows and other research problems is expanded on where appropriate the review concludes with a discussion of recent trends in tls instrument development and their potential impact on the use of tls in the earth sciences in the future

interactions between continental breakup dynamics and large scale delta system evolution insights from the cretaceous ceduna delta system bight basin southern australian margin 1 the interpretation of two regional seismic reflection profiles and the construction of a balanced cross section through the southern australian margin bight basin are designed to analyze the influence of the australia antarctica continental breakup process on the kinematic evolution of the cretaceous ceduna delta system the data show that the structural architecture of this delta system consists of two stacked delta systems the lower white pointer delta system late albian santonian is an unstable tectonic wedge regionally detached seaward above late albian ductile shales sequential restoration suggests that the overall gravitational sliding behavior of the white pointer delta wedge 45 km of seaward extension i e 27 is partially balanced by the tectonic denudation of the subcontinental mantle we are able to estimate the horizontal stretching rate of the mantle exhumation between 2 and 5 km ma 1 the associated uplift of the distal part of the margin and associated flexural subsidence in the proximal part of the basin are partially responsible for the decrease of the gravitational sliding of the white pointer delta system lithospheric failure occurs at 84 ma through the rapid exhumation of the mantle the upper hammerhead delta system late santonian maastrichtian forms a stable tectonic wedge developed during initial slow seafloor spreading and sag basin evolution of the australian side margin lateral variation of basin slope related to the geometry of the underlying white pointer delta wedge is associated with distal raft tectonic structures sustained by high sedimentation rates finally we propose a conceptual low angle detachment fault model for the evolution of the australian antarctic conjugate margins in which the antarctic margin corresponds to the upper plate and the australian margin to the lower plate

utilizing dems derived from lidar data to analyze morphologic change in the north carolina coastline by using digital elevation model dem data derived from light detection and ranging lidar data an approximately 70 km stretch of the southern north carolina coastline was studied the coastline consists of five barrier islands located between masonboro island at the southern extent and topsail island at the northern extent the high resolution dem data allowed for a comprehensive visual quantitative investigation into the spatial patterns of morphologic change that occurred to the barrier islands oceanfront beaches between 1997 and 2000 this study also demonstrated the usefulness of using laser altimetry to examine barrier islands response to level of tropical activity and showed that the coastal process of overwash was recognized as an integral component of barrier island landward migration means of net volumetric change per unit area m 3 m 2 for study areas of different beach management practices characterized as developed undeveloped and nourished beaches on a yearly basis for the period between 1997 and 2000 were derived t test of the means has been conducted and results showed that beaches differed statistically if different management practices were applied to them and the differences were minimized or disappeared if sequential hurricanes or storms affected the beaches d 2002 elsevier science inc all rights reserved

review of major shale dominated detachment and thrust characteristics in the diagenetic zone part i meso and macro scopic scale there is considerable variability in the thickness structure and macroscopic deformation style within shale prone major thrust zones which also impacts the structural style in the overlying and sometimes the underlying section the properties and percentages of clay minerals and percentages of organic material quartz and calcite affect fault zone weakness and behaviour the distribution of competent units within a shale prone zone can also significantly affect fault zone architecture even over short strike distance of 10s to 100s of metres other influences include high pore fluid pressures and associated veins deformation of the fault zone may disrupt the original principal displacement zones and force them to relocate including switching lithologies calcite veins can become concentrated locally in the fault zone and become a focus of fault zone weakness we still need many more descriptions of shale prone fault zones to understand the potential variations in thrust sheet structural style caused by differences in shale detachment characteristics the variations in structural style in the hanging walls of shale detachments are broad and range between the sledge runner style in many appalachian examples and the extensive closely spaced imbricate style of the osen roa detachment southern norway such contrasts are related to several factors including thrust sheet mechanical stratigraphy thickness of the overburden lateral continuity of the detachment detachment mechanical properties composition pore fluid pressures presence absence of higher level detachments and strain rate in many structural locations and at many scales shale prone sequences will pile up to produce over thickened masses cleavage duplexes s c fabrics duplexes imbricates pseudo duplexes and vein formation can all contribute to the thickening at nested scales a mixture of brittle and solution diffusion processes overall cause the affected unit to exhibit flow like characteristics while the broad principles are now well established considerable work remains to be done understanding the full range of structural geometries associated with shale detachments what factors regarding the nature of the detachments affect overlying structural styles rates of deformation and the controls on deformation mechanisms within the thrust zones

sediment creep on slopes in pelagic limestones upper jurassic of northern calcareous alps austria abstract slump structures in upper jurassic pelagic limestones of the northern calcareous alps were studied using methods of ductile structural geology the early deformation observed cannot be explained by conventional models for slumping commonly describing slump complexes with an extending upper and contracting lower part instead the structures suggest distributed bedding parallel surficial stretching and folding localized by roll over normal faulting the initially isoclinal and recumbent folds are pervasively overprinted by stretching causing reorientation of fold axes into the downslope direction transport of folds separates antiformal and synformal hinges and the resulting isolated hinges resemble intrafolial folds in metamorphic terranes only folds formed late in the process of lithification allow insight in the early stages of fold evolution we suggest that this type of early deformation represents sediment creep that may be characteristic for slump structures in pelagic carbonates

gravity driven deformation controlled by the migration of the delta front the plio pleistocene of the eastern niger delta abstract the occurrence in large shelf edge deltas of gravity driven deformation related to overpressured shales is now well documented in many natural examples in this paper we explored the implications of the migration of the delta front on the kinematics of gravity driven deformation in a case where the stratigraphic framework is detailed enough to discuss deformation kinematics and sedimentary supply at high temporal resolution 0 1 myr we determined the deformation for the last 4 myr at the scale of the whole eastern niger delta the upslope extensional domain showed ew asymmetric grabens the transitional domain displayed i deformation restricted to folding to the east and ii a thicker sedimentary wedge and a larger deformation accommodated by thrust related folds to the west the compressional front was a fold and thrust belt extensional deformation decreased in amount and rate over the plio pleistocene it also evolved significantly from distributed over the whole area to localized either to the western or eastern domains over that period the compressional deformation followed the same evolution i e the greater the extension the greater the compression in either time or space demonstrating the strong coupling between the extensional and compressional domains gravity deformation during the plio pleistocene was driven by the continental slope spanning the coastal plain to distal deposits over the oceanic crust about 2800 m of gravity potential the superimposition of the delta front migration area and the extensional domain show that the associated pressure gradient localized the extensional domain deformation was closely linked to migrations of the delta front and the sedimentary supply reaching the delta i the decrease in extension rate over the plio pleistocene is related to a decrease in sedimentary supply over the plio pleistocene and ii the spatial variations in extension intensity and rate are related to spatial variations of sedimentary supply

deformation and recrystallization mechanisms in actively extruding salt fountain microstructural evidence for a switch in deformation mechanisms with increased availability of meteoric water and decreased grain size qum kuh central iran microstructural study of rocksalt samples from an active salt fountain qum kuh central iran enabled to identify the relative contribution of different deformation mechanisms on extrusive salt flow the microstructural study combined reflected and transmitted light microscopy of gamma irradiated thin sections textural analysis of digitized microstructures and electron back scattered diffraction ebsd deformation microstructures record the strongly variable deformation conditions of salt flow in the diapiric system from the diapiric stem towards the distal part of the mature viscous fountain high stress deformation conditions typical for diapiric stems are recorded in the small subgrains within the porphyroclasts of all documented samples recovery and recrystallization due to divergent and decelerating flow associated with differential stress drop in the salt extrusion above the diapiric orifice is reflected by abundant growth band microstructures this study reveals also evidence for penetration of rainwater into the salt mass and documents the switch from the dominant dislocation creep into dominant solution precipitation creep from the upper part to the distal part of the fountain this deformation mechanism switch is provided by influx of meteoric water and grain size decrease likely controlled by subgrain rotation and grain boundary migration recrystallization

beach dune morphological relationships and erosion accretion an investigation at five sites in england and wales using lidar data abstract the critical relationships between beach and nearshore parameters and the erosion accretion status of frontal dunes have been investigated using lidar data complemented by data obtained from conventional topographic and bathymetric surveys at five dune systems in england and wales morphometric parameters calculated from the lidar data demonstrate the presence of a general relationship between beach morphology dune morphology and erosion accretion eroding dunes were found to be associated with narrower steeper beaches whilst accreting dunes were associated with wider low angle beaches however the critical beach width mean slope angle separating eroding dunes from stable or accreting dunes was found to vary between sites at any given site changes in beach width slope over time can be used to provide an early warning of changes in frontal dune erosion accretion behaviour

excursus on gravity gliding and gravity spreading abstract the terms gravity gliding and gravity spreading have long been used to describe deformation driven by gravity alone however the traditional definitions of these terms cannot be applied unambiguously in many situations the primary difficulties arise because rocks are not ideally rigid detachment surfaces may not be planar substrates may be deformable and rock bodies do not deform in isolation the term gravity spreading is still useful if it is simply defined as gravity driven lateral extension and vertical contraction regardless of basal slope and coherence of the body i suggest that the term gravity gliding should be used rarely and only if the defining characteristics are clearly stated and understood in most cases more detailed descriptions should be used instead of or in addition to either of these terms to capture the behavior of rock masses deforming under gravity

the application of a long range laser scanner for monitoring volcanic activity on mount etna abstract there is a requirement for rapid remote monitoring of ground deformation of volcanoes especially during eruptions a long range reflector less laser scanning instrument manufactured by riegl laser measurement systems was used on mount etna in october 2000 and its potential for monitoring ground surface changes associated with volcanic activity was evaluated the 3dlm lr1 scanner system can measure distances up to 2 km with an accuracy of 25 mm in typical conditions measurement rates range from 1 point per second at 2 km to 4 points per second at 10 m the system also records reflective intensity and this proved useful in distinguishing between different types of volcanic material cloud and gas obscured some measurements but the scanning nature of the instrument coupled with effective data filtering software allowed robust digital terrain models to be created

wedge geometry and detachment strength in deepwater fold thrust belts deepwater fold thrust belts dwftbs have been classified into three groups according to the present day stress regime and tectonic setting near field stress driven dwftbs are usually associated with passive margins they are thin skinned gravitational deformation with thick salt or overpressured shale detachments dwftbs formed by far field stresses are primarily associated with continent convergent zones and active margins mixed near and far field stress driven dwftbs have aspects of both thin skinned and thick skinned tectonics detachment strength is the primary control on the first order wedge geometry of a dwftbs and is controlled by lithology and overpressure based on analysis of fault strength calculated from critical taper measurements it is found that detachments beneath different classes of dwftbs are not analogously weak near field stress driven dwftbs at passive margins generally have smaller wedge taper angles and weaker detachments far field stress driven and mixed near and far field stress driven dwftbs at continent convergent zones or active margins generally have larger wedge taper angles and stronger detachments differences in the way overpressures are generated and dissipated between the different types of dwftb are thought to be primarily responsible for the systematic variations in shale prone basal detachment weakness found in this study clear lithology related differences in dwftb critical taper are shown between shale higher taper and salt lower taper dominated basal detachments

allochthonous salt structure and stratigraphy of the north eastern gulf of mexico part ii structure abstract the kinematic evolution of allochthonous salt in the north eastern gulf of mexico proceeds in three stages 1 since its middle jurassic deposition the louann salt was loaded by sediments causing episodic basinward movement of salt ultimately leading to large concentrations of salt masses in a slope environment by the end of the lower cretaceous 2 a regime of starved sedimentation during late cretaceous and early oligocene is responsible for the stabilization of these early salt accumulations 3 with renewed rapid accumulation of sediments during the neogene and pliocene extensive allochthonous salt tongues and sheets formed by gravity spreading within the younger sediments of the slope autochthonous salt allochthonous salt and detached allochthonous salt are typical stages of evolution major down to the basin growth faults separate allochthonous salt sheets from their original feeder stocks extension along down to the basin master growth faults is compensated mainly by salt withdrawal and partly by basinward shortening

balancing deformation in nw borneo quantifying plate scale vs gravitational tectonics in a delta and deepwater fold thrust belt system abstract recent gps measurements demonstrate that nw borneo undergoes 4 6 mm of plate scale shortening a year which is not accommodated by plate scale structures the only geological structure in nw borneo described to accommodate on going shortening is the baram delta system located on the outer shelf to basin floor delta toe fold thrust belts are commonly thought to be caused by margin normal compressional stresses generated by margin parallel upslope gravitational extension the baram delta system is divided into three neotectonic provinces 1 an inactive onshore and inner shelf region of inversion superimposed on an older extensional deltaic province 2 an outer shelf region of present day deltaic extension and 3 a compressional delta toe however it is uncertain whether compression in the delta toe area is purely driven by gravity i e shortening is less than upslope extension or if there is a component of regional shortening involved which can only be demonstrated if shortening is greater than upslope extension in order to quantify the balance between the shortening related to the upslope gravitational extension and the shortening related to the regional geodynamic framework in the baram delta system we have used a geomechanical code based on the finite element method and conservation of mass and momentum dynel 2d this enabled us to reconstruct the tectonic evolution of the delta and to demonstrate for the first time that the total shortening observed in the delta toe does not balance against the active extension in the delta top with the system exhibiting 1 8 shortening overall or 2 0 km this additional shortening is therefore attributed to plate scale shortening across nw borneo produced by far field compression using a convergence rate of 4 mm y 1 demonstrated by gps measurements the delta toe has accommodated far field compression only in the last 0 5 my

an experimental investigation of gravity driven shale tectonics in progradational delta abstract many deltas exhibit gravitational deformation of their sedimentary cover in these systems the decollement layers do not always consist of rock salt but sometimes of overpressured shale unlike salt the efficiency of detachment in shale depends on the magnitude of fluid overpressures and it varies through time and space as rapid sedimentary burial progrades into deeper water as a result the gravity deformational domains are progressively translated seaward sandbox models involving high air pore pressures were used to simulate such gravity driven shale tectonics in prograding deltas models were built with sand of various permeabilities and air was injected to simulate the mechanical effects of fluid overpressure our apparatus for the injection of air allowed us to control subsurface pressures in space and time during the experiments and it was used to simulate the advance of the front of the overpressured domain during the sedimentary progradation in our models sand kept obeying a frictional behavior for medium to high pore pressures and the detachment appeared as very thin shear bands compressional belts that formed during the experiment were dominated by asymmetric basinward verging fore thrusts as is often observed in deep water shale detached foldbelts where the value of fluid pressures approached that of the lithostatic stress sand was fluidized resulting in ductile strains analogous to what occurs in highly overpressured mobile shale during progradation ancient buried thrustbelts were reactivated thereby controlling later extension during the experiments sand volcanoes analogous to mud volcanoes formed in relation with tectonic structures some of them developed near normal faults but many of them formed directly above old buried thrusts

remote sensing data types and techniques for lahar path detection a case study at mt ruapehu new zealand mt ruapehu is new zealand s most active onshore volcano in 2007 the volcano produced a large lahar following a break out from the summit crater lake here satellite and airborne remote sensing and image processing is used to extract the path of the lahar using aster and spot5 visible and near infra red imagery alos palsar l band synthetic aperture radar data and airborne lidar the results obtained from each of these datasets were compared to the lahar deposit manually digitized from aerial photography spot5 imagery produced the most accurate map of the lahar deposit 77 correct even though these data were acquired a year after the event this is attributed to the spatial resolution of the data the alos palsar coherence mapping calculated from images acquired 2 months before and nine months after the lahar was not as accurate as that obtained using the optical imagery 43 correct but this was still considered an important tool for acquiring data during cloudy periods lidar topographic data collected to constrain geomorphic changes caused by the lahar was the least accurate in terms of mapping the lahar path 28 correct no single technique was deemed to be the most accurate under all circumstances and a combination of data types would produce the best results by combining the satellite and lidar data it was possible to accurately classify 92 of the lahar path

the impact of syn and post extension prograding sedimentation on the development of salt related rift basins and their inversion clues from analogue modelling abstract various studies have demonstrated the intrinsic interrelationship between tectonics and sedimentation in salt related rift basins during extension as well as during their inversion by compression here we present seven brittle ductile analogue models to show that the longitudinal or transverse progradation of sediment filling an elongate extensional basin has a substantial impact on the growth of diapirs and their lateral geometrical variations we use five extensional models to reveal how these prograding systems triggered diapir growth variations from proximal to distal areas relative to the sedimentary source in the models continuous passive diapir walls developed after a short period of reactive active diapiric activity during syn extensional homogeneous deposition in contrast non rectilinear diapir walls grew during longitudinal prograding sedimentation both longitudinal and transverse post extensional progradation triggered well developed passive diapirs in the proximal domains whereas incipient reactive active diapirs incipient roller like diapirs or poorly developed diapirs were generated in the distal domains depending on the modelled sedimentary pattern two models included final phases of 6 and 10 shortening associated with basin inversion by compression respectively to discriminate compressional from purely extensional geometries with the applied shortening the outward flanks of existing diapir walls steepened their dips from 8 17 to 30 50 likewise 6 of shortening narrowed the diapir walls by 32 72 with their fully closing salt welds with 10 of shortening we compare our results with the distribution of salt walls and minibasins of the central high atlas diapiric basin in morocco which was infilled with a longitudinally prograding mixed siliciclastic and carbonatic depositional sequence during the early middle jurassic with a minimum thicknesses of 2 5 4 0 km

the importance of high resolution monitoring in erosion and deposition dynamics studies examples from estuarine and fluvial systems abstract erosion and deposition processes lie at the centre of geomorphological explanation but progress in understanding has been limited by a lack of appropriate high resolution monitoring methodologies which permit detection of erosion and deposition dynamics this paper presents a case for monitoring erosion and deposition at high temporal resolutions and uses hypothetical approaches supported by example erosion and deposition events and analyses drawn from estuarine and fluvial systems the paper first presents testable hypotheses to demonstrate the complexity of possible event combinations sequences and juxtapositions for the erosion driving forces which underpin the need for high resolution monitoring second it summarises recent improvements to the photo electronic erosion pin peep automatic erosion and deposition monitoring system including the novel concept of thermal consonance timing tct which is particularly promising because it helps to define the timing of nocturnal events and through the entire hydrograph third example results are discussed from high resolution monitoring of bank erosion at a tidal site at burringham on the river trent in northern england tidal banks are revealed to be much more dynamic than previous conventional monitoring has indicated a key result is that because the high resolution approach allows erosional and depositional activity to be assigned to specific periods of tidal inundation it becomes possible for the first time routinely to produce event based erosion 36 mm h 1 and deposition rates 4 5 and 8 4 mm h 1 such rate determinations are potentially very useful in the field validation of sedimentological and geomorphological models including grain settling and resuspension theory fourth through a longer term of aggregated daily data a striking 2 week cycle of deposition and erosion emerges which correlates most strongly with spring neap tidal cycling but is moderated by wind stress effects sediment was deposited on the bank relatively quickly over 4 5 days but then removed by erosion rather slowly over 9 10 days fifth the dangers of low resolution monitoring are illustrated by comparing the daily peep data set with a series resampled at a lower 14 day frequency to simulate the information generated by conventional resurvey methodologies the low frequency series failed adequately to represent the cyclicity mean range variability and trend of bank elevation changes and without this dynamics information rate and process definition is very difficult largely because of self concealing activity sixth a useful advance is illustrated by the fluvial erosion sequence for the river wharfe n england this shows how tct can generate rare and important results with the definition of the precise time of an erosion event within the hydrograph bank retreat here occurred very quickly after initial inundation and within 4 h of the flow peak information which can be used to define thresholds for entrainment e g critical shear stresses such high resolution monitoring helps to unravel some of the erosional effects of complex sequences combinations and juxtapositions of similar or different forcing events finally high resolution approaches have been adopted worldwide for fluvial estuarine mudflat and canal systems but considerable potential exists for their development and use in these and other contexts e g gully hillslope beach and dune environments to improve understanding and modelling of geomorphological processes more widely

evolution of solution structures in a deformed quartz arenite geometric changes related to permeability changes abstract quartz arenite of the silurian keefer sandstone at a site in west virginia u s a records an early pervasive solution related deformation by grain interpenetration volume losses measured by the pss method show shortening directions from both diagenetic compaction and early tectonic layer parallel shortening later solution related tectonic deformation during folding formed transgranular stylolites along pre existing faults or in rock volumes with abundant microfractures thus the geometry of solution related deformation changed progressively from pervasive at grain scale to focused along transgranular surfaces we propose that this geometric change resulted from intense porosity and permeability reduction during diagenetic cementation and early layer parallel shortening which required fluids to exploit tectonically created pathways along faults or networks of microfractures during later deformation

simultaneous inversion for lateral velocity variations and hypocenters in the yellowstone region using earthquake and refraction data a three dimensional upper crustal p wave velocity structure of the yellowstone region was determined by simultaneous inversion using pg refracted arrival times and earthquake generated direct p wave arrival times the velocity structure was modeled by a two layer block configuration with the velocity of the surface layer fixed the inversion was performed on a 14 4 km thick second layer 5 6 blocks using an optimal block size of 21 2 18 3 km and incorporated the method of separation of parameters results show volumes of higher velocities approximately 6 3 km s north of the yellowstone caldera that correlate with gravity anomaly highs and are interpreted to be associated with near surface crystalline basement the upper crust beneath the caldera showed an average velocity of 5 8 km s with prominent low velocity zones of 4 9 and 5 2 km s in the northeast and southwest portions of the caldera respectively the 4 9 km s low velocity layer in the northeast corner of the caldera coincides with a localized 20 mgal bouguer gravity low and the largest area of hydrothermal activity in yellowstone national park relocating earthquakes with the new velocity model showed a systematic migration of epicenters radially toward the caldera by an average of 1 2 km relative to locations using a homogeneous velocity model

use of lidar derived images for mapping old landslides under forest large deep seated landslides are common features in the flemish ardennes belgium as most of these old 100 years landslides are located under forest in this hilly region aerial photograph interpretation is not an appropriate landslide mapping method this study tested the potential of lidar light detection and ranging images for mapping old landslides under forest landslide inventory maps were created for a 125 km2 area by applying the expert knowledge of seven geomorphologists to lidar derived hillshade slope and contour line maps in a gis environment each of the seven lidar based landslide inventories was compared i with the other six ii with a detailed field survey based inventory and iii with a comparable study in which topographic data were extracted from a topographical map the combination of the percentage of field landslides indicated by an expert and the percentage of positional discrepancies expressed in terms of positional mismatch were used to evaluate the quality of the lidar based inventory maps high quality lidar derived landslide inventory maps contain more than 70 per cent of the landslides mapped during the field survey and have positional discrepancies smaller than 70 per cent when compared with the field survey based inventory map four experts and the combination map of all experts satisfied these criteria together the seven experts indicated all landslides mapped in the field importantly lidar enabled the experts to find ten new landslides and to correct the boundaries of eleven of the 77 landslides mapped during the field survey hence this study showed that large scale lidar derived maps analysed by experienced geomorphologists can significantly improve field survey based inventories of landslides with a subdued morphology in hilly regions copyright 2006 john wiley sons ltd

dynamics of orogenic wedges and the uplift of high pressure metamorphic rocks subduction accretion complexes can be approximated as wedge shaped continua with a rigid buttress behind and a subducting litho spheric slab beneath thick wedges undergoing prograde metamorphism have a negligible long term yield strength and are likely to exhibit a complex nonlinear viscous rheology such a wedge will tend to deform internally until it reaches a stable configuration in which the gravitational forces generated by the wedge geometry balance the traction exerted on its underside by the subducting slab accretion of material at the wedge front will lengthen the wedge and cause it to shorten internally to regain the stable geometry this shortening will be expressed as late out of sequence thrusting backthrusting and folding conversely underplating of sediment or crustal slices will thicken the wedge which may need to extend internally to regain stability extension will cause listric normal faults that may merge downward into zones of ductile extension continued underplating at depth and compensating extension above provides a mechanism for bringing high p low t metamorphic rocks to upper levels in the rear of the wedge where they are commonly observed many major tectonic boundaries in convergent orogens such as the coast range thrust in the franciscan complex major nappe contacts in the alps and the contact between the nevado filabride and higher betic nappe complexes in the betic cordillera show abrupt increases in metamorphic grade downward across them this is consistent with their origin or reactivation as uplift related extensional structures

preorogenic folds and syn orogenic basement tilts in an inverted hyperextended margin the northern pyrenees case study the chainons bearnais cb north pyrenean zone resulted from the cenozoic contractional reactivation of the salt tectonics bearing hyperextended margin that initiated at the europe iberia transition during the early cretaceous in this tectonic scenario assessing the relative contribution of extension and contraction to the present day structure is crucial to reconstruct the hyperextended margin geometry and to quantify the subsequent shortening this study undertakes this issue by defining the relationship between folding and two bedding independent references peak temperature isotherms and paleomagnetic data isotherms were reconstructed from 76 new measurements of raman spectroscopy on carbonaceous materials rscm and indicate temperatures at the time of peak metamorphism in the cb 110 85 ma end of extension they are shallowly to moderately northwards dipping and cut across most of the folds deforming the mesozoic units paleomagnetic data from 29 sites evidence a widespread remagnetization carried by pyrrhotite that was probably blocked during the early paleogene before the onset of continental collision and postdated folding in the cb abnormal inclinations in this remagnetization suggest syn collision tilts up to 60 to the north in the back limb of the axial zone based on the presented data set we propose that the folding of the cover above the evaporitic decollement was almost fully completed by the end of the cretaceous extension with 85 100 of the dip of fold limbs being acquired before the remagnetization time cenozoic contraction reactivated the extensional faults in the shallow basement as top to the s thrusts leading to the passive transport and northwards tilting of the folded cover

extensional fault systems in sedimentary basins a review of analogue model studies abstract scaled analogue models have provided graphic new insights into the progressive development of extensional fault systems this paper reviews recent results of an on going analogue modelling programme and compares the structural styles in the models with examples of natural extensional fault systems four fundamental model styles scaled to simulate deformation in brittle sedimentary rocks in the upper 10 km of the crust are reviewed extension above a basal detachment which undergoes stretching over a limited are produces an asymmetric rift graben bounded by planar faults and in which the internal deformation is accommodated by rotational domino faults these experimental results are directly comparable to structures found in intracontinental rifts extension above a basal detechment which undergoes extension under the whole model and which has no constraints at the ends produces domino style fault arrays in the pre rift sequence and listric growth faults in the syn rift sequence these results compare with highly extended rift basins and terranes such as the basin and range province usa extension above a simple listric fault produces a characteristic hangingwall roll over and crestal collapse graben system at high values of extension superposed crestal collapse grabens occur and a fan of listric growth faults is developed these structures bear striking similarities to growth faults in progradational delta systems ramp flat listric extensional fault systems using sand mica models produce a characteristic family of structures with an upper roll over crestal collapse system a ramp syncline and reverse fault fold zone and a lower roll over crestal collapse system an example of a ramp flat fault system from the gulf coast usa is presented as a comparison with the analogue model results preliminary results of three dimensional extensional model experiments are presented to illustrate the complexities in such fault systems in all of the experimental models it is found that the geometry of the underlying detachment system exerts fundamental control on structures produced in the hangingwall the analogue models illustrated in this review provide valid geometric and kinematic templates for the progressive evolution of extensional fault systems in sedimentary basins

impact of solid second phases on deformation mechanisms of naturally deformed salt rocks kuh e namak dashti iran and rheological stratification of the hormuz salt formation abstract viscosity contrasts displayed in flow structures of a mountain namakier kuh e namak dashti between weak second phase bearing rock salt and strong pure rock salt types are studied for deformation mechanisms using detailed quantitative microstructural study while the solid inclusions rich dirty rock salts contain disaggregated siltstone and dolomite interlayers clean salts reveal microscopic hematite and remnants of abundant fluid inclusions in non recrystallized cores of porphyroclasts although the flow in both the recrystallized dirty and clean salt types is accommodated by combined mechanisms of pressure solution creep ps grain boundary sliding gbs transgranular microcracking and dislocation creep accommodated grain boundary migration gbm their viscosity contrasts observed in the field outcrops are explained by 1 enhanced ductility of dirty salts due to increased diffusion rates along the solid inclusion halite contacts than along halite halite contacts and 2 slow rates of intergranular diffusion due to dissolved iron and inhibited dislocation creep due to hematite inclusions for clean salt types rheological contrasts inferred by microstructural analysis between both salt rock classes apply in general for the dirty salt forming lower hormuz and the clean salt forming the upper hormuz of the hormuz formation and imply strain rate gradients or decoupling along horizons of mobilized salt types of different composition and microstructure

niger delta gravity driven deformation above the relict chain and charcot oceanic fracture zones gulf of guinea insights from analogue models abstract the niger delta is a classic example of a passive margin delta that has gravitationally deformed above an overpressured shale decollement the outboard niger delta clastic wedge including the akata formation overpressured shale decollement is differentially thickened across relict oceanic basement steps formed at the chain and charcot fracture zones in this study five analogue models were applied to investigate the effects of a differentially thickened overpressured shale decollement across relict stepped basement on niger delta gravity driven deformation gravity driven delta deformation was simulated by allowing a lobate layered sandpack to deform by gravity above a ductile polymer a first series of experiments had a featureless horizontal basement whereas a second series had differentially thickened polymer above niger delta like basement steps two syn kinematic sedimentation patterns were also tested surface strains were analysed using digital image correlation and key models were reconstructed in 3d all five model deltas spread radially outward and formed plan view arcuate delta top grabens and arcuate delta toe folds the arcuate structures were segmented by dip oriented radial grabens and delta toe oblique extensional tear faults which were formed by along strike extensional strains during spreading basement steps partitioned delta toe gravity spreading into dual divergent directions similarities between the analogue model structures and the niger delta strongly suggest a history of outward radial gravity spreading at the niger delta the niger delta western lobe has potentially spread downdip more rapidly due to a thicker or more highly overpressured underlying akata fm shale detachment faster western lobe spreading may have produced the niger delta toe dual lobe geometry perturbed up dip niger delta top growth fault patterns and implies that western lobe toe thrusts have been very active

analysis of lidar derived topographic information for characterizing and differentiating landslide morphology and activity abstract this study used airborne laser altimetry lidar to examine the surface morphology of two canyon rim landslides in southern idaho the high resolution topographic data were used to calculate surface roughness slope semivariance and fractal dimension these data were combined with historical movement data global positioning systems gps and laser theodolite and field observations for the currently active landslide and the results suggest that topographic elements are related to the material types and the type of local motion of the landslide weak unconsolidated materials comprising the toe of the slide which were heavily fractured and locally thrust upward had relatively high surface roughness high fractal dimension and high vertical and lateral movement the body of the slide which predominantly moved laterally and consists mainly of undisturbed older canyon floor materials had relatively lower surface roughness than the toe the upper block consisting of a down dropped section of the canyon rim that has remained largely intact had a low surface roughness on its upper surface and high surface roughness along fractures and on its west face unrelated to landslide motion the upper block also had a higher semivariance than the toe and body the topographic data for a neighboring older and larger landslide complex which failed in 1937 are similarly used to understand surface morphology as well as to compare to the morphology of the active landslide and to understand scale dependent processes the morphometric analyses demonstrate that the active landslide has a similar failure mechanism and is topographically more variable than the 1937 landslide especially at scales 20 m weathering and the larger scale processes of the 1937 slide are hypothesized to cause the lower semivariance values of the 1937 slide at smaller scales