precipitation over eastern south america and the south atlantic sea surface temperature during neutral enso periods the dominant mode of coupled variability over the south atlantic ocean is known as south atlantic dipole sad and is characterized by a dipole in sea surface temperature sst anomalies with centers over the tropical and the extratropical south atlantic previous studies have shown that variations in sst related to sad modulate large scale patterns of precipitation over the atlantic ocean here we show that variations in the south atlantic sst are associated with changes in daily precipitation over eastern south america rain gauge precipitation satellite derived sea surface temperature and reanalysis data are used to investigate the variability of the subtropical and tropical south atlantic and impacts on precipitation sad phases are assessed by performing singular value decomposition analysis of sea level pressure and sst anomalies we show that during neutral el nino southern oscillation events sad plays an important role in modulating cyclogenesis and the characteristics of the south atlantic convergence zone positive sst anomalies over the extratropical south atlantic sad negative phase are related to increased cyclogenesis near southeast brazil as well as the migration of extratropical cyclones further north as a consequence these systems organize convection and increase precipitation over eastern south america

a field experiment for calibrating landslide time of failure prediction functions over the last decades time of failure semi empirical prediction functions have been developed and applied to different landslides with mixed results in this study a field experiment was carried out to calibrate these functions with the simultaneous consideration of small size landslides and landslides that occur on slopes modified by human activities four years of continuous monitoring using an integrated platform consisting of both traditional sensors i e inclinometers piezometers load cells topographic measurement and innovative remote sensing equipment i e terrestrial sar interferometer resulted in the collection of a notably large amount of data several landslides affecting different slopes i e cut slopes cut slopes covered by spritz beton and slopes stabilised by anchored bulkheads were observed as part of the experiment thus facilitating the inference of detailed information for the pre failure behaviour nine landslides were back analysed thus allowing for calibration of the failure prediction functions for different types of slopes from these observations it was found that events occurring on slopes modified by human interventions could be effectively predicted using the voight function if suitable parameters are used as a general remark the landslides that originate from cut slopes in natural terrain behave similar to large landslides reported in the literature similar values of a and while landslides that originate from cut slopes covered by spritz beton and slopes stabilised by anchored bulkheads show values that are significantly lower and a values that are significantly higher than those of landslides on natural terrains

mechanisms by which gulf of guinea and eastern north atlantic sea surface temperature anomalies can influence african rainfall abstract the sensitivity of precipitation over west africa to sea surface temperature anomalies sstas in the gulf of guinea and the eastern north atlantic is studied using a gcm results from nine perpetual july simulations with various imposed sstas are presented and analyzed to reveal associations between the precipitation and sst fields via large scale circulation and atmospheric moisture anomalies rainfall increases over the guinean coast and decreases over the congo basin when warm sstas are present in the gulf of guinea these precipitation perturbations are related to the forcing of a kelvin and a rossby wave the former is associated with a weakening of the walker circulation while the latter strengthens the west african monsoon rainfall over west africa is less sensitive to cold sstas than to warm anomalies three contributing factors are identified as follows 1 latitude of the sst forcing 2 background flow and 3 nonlinearity of the clausius clapeyron equation no more than a 20 effec

early detection of first time slope failures using acoustic emission measurements large scale physical modelling early warning systems for slope instability need to alert users of accelerating slope deformation behaviour to enable safety critical decisions to be made this study shows that acoustic emission

clinoforms and clinoform systems review and dynamic classification scheme for shorelines subaqueous deltas shelf edges and continental margins abstract clinoforms are inclined and normally basinward dipping horizons developed over a range of spatial and temporal scales in both siliciclastic and carbonatic systems the study of clinoform successions underpins sequence stratigraphy and all efforts to reconstruct the relative partitioning of reservoir seal and source rocks along shoreline to basin floor profiles here we review clinoform research and propose a more systematic description and classification of clinoforms this is a crucial step to improve predictions of facies and lithology distribution within shoreline to continental shelf and abyssal plain successions together with the genesis drivers and dynamics of their constituent sedimentary units four basic clinoform types are here distinguished in delta shorelines lacustrine and marine environments on the basis of their overall spatial and temporal scale morphology outbuilding dynamic and geodynamic and depositional setting 1 2 delta scale clinoforms which in turns are sub divided into shoreline and delta scale subaqueous clinoforms 3 shelf edge clinoforms and 4 continental margin clinoforms delta scale clinoform sets are tens of metres high and typically represent 1 103 kyr with progradation rates ranging from 1 000 100 000 m kyr for shorelines and subaerial deltas to 100 20 000 m kyr for subaqueous deltas shelf edge clinoform sets are hundreds of metres high and are nucleated and accreted in 0 1 20 myr usual progradation rates of 1 100 m kyr by successive cross shelf transits of delta scale clinoforms continental margin clinoform sets are thousands of metres high hallmark key geodynamic crustal boundaries e g continent ocean transition and slowly prograde basinwards in ca 5 100 myr with typical rates of 0 1 10 m kyr as a consequence of the very different progradation rates and of the difficulty of large scale clinothems to backstep during transgressions shorelines are the most dynamic clinoforms with regards to position continental margins the least and shelf edges are intermediate shortly after a transgression therefore the four clinoform types may prograde synchronously along shoreline to abyssal plain transects forming compound clinoform systems during the subsequent regressive cycle however due to the dissimilarity in progradation rates different clinoform types will normally merge progressively with each other giving rise to hybrid clinoforms e g shelf edge deltas and fewer depositional breaks in slope are distinguished along a single shoreline to abyssal plain transect overall all clinoform systems are the result of the dynamic evolution of compound and hybrid clinoforms along a temporal and spatial continuum regulated by the cyclical backstepping of the smaller scale system within natural progradational retrogradational cycles of larger scale clinothem outbuilding all clinothem types may show either an accretionary active or draping passive style depending on the proximity to the sediment source draping clinothems are nearly always composed of condensed fine grained sediments while actively accreting clinothems can be composed of predominantly coarse grained i e reservoir forming or predominantly fine grained i e non reservoir lithotypes a novel hierarchical classification scheme for both recent and ancient clinoforms is here proposed consisting of 12 classes the four basic clinoform types delta scale shoreline delta scale subaqueous shelf edge and continental margin are sub divided into eight accretionary active and draping passive sub types 8 division each accretionary sub type is then sub divided into a sandstone prone and mudstone prone variant 12 division which can be at least tentatively predicted on the basis of the clinoform morphology even in the absence of direct stratigraphic logs

vertical sequence and lateral transitions in the facies of a barred nearshore environment abstract nine tube cores 7 cm in diameter and up to 150 cm long from a nearshore crescentic bar in kouchibouguac bay new brunswick canada reveal the vertical sequence and lateral transitions of facies previously identified only in shallow box cores the facies are a inner shelf shoreface transition bioturbated fine sands and silts with remnant primary structures b seaward slope planar lamination in medium to fine sands dipping gently seaward and composite bed sets of planar to ripple cross lamination in fine sand chevron lamination is rare c bar crest low angle planar lamination dipping both landward and seaward and medium scale trough cross lamination in medium to coarse sands d landward slope planar lamination dipping landward with small scale la dward dipping trough cross lamination occasionally small to medium scale trough cross lamination is found with seaward dips e trough massively bedded lags of coarse gravelly sands with abundant shell fragments contrast with isolated very thin units of massive silt and units of well sorted sands the latter display subhorizontal planar lamination and small to medium scale trough cross lamination polymodal dips indicate bed form migration landward alongshore and offshore vertical sequences and lateral transitions seaward of the bar crest suggest that three wedge shaped units inner shelf shoreface transition seaward slope bar crest interdigitate in an offlap onlap sequence to landward the trough and landward slope facies interfinger complexly while the crest facies forms a simple onlap over landward slope facies total reworking of sediments within the bar trough system is expected every 5 to 6 years and long term preservation is limited to the inner shelf shoreface transition seaward slope and trough facies

on the connection between benguela and equatorial atlantic ninos and the role of the south atlantic anticyclone for the eastern tropical atlantic two recurring el nino like phenomena with high interannual sst anomalies have been described one centered in the equatorial region as part of the atlantic zonal mode and one off angola referred to as benguela nino both events are supposed to be generated not locally but by a relaxation of the trade winds in the western equatorial atlantic here the connection between sst variations in the two regions is investigated with observational data sets as well as ocean model simulations they are correlated to such an extent that joint events should rather be viewed as one atlantic nino an intriguing feature counterintuitive in view of the remote forcing mechanism is that sst anomalies off angola precede those in the equatorial atlantic we show this behavior to be related to the difference in thermocline depths and a different seasonality of interannual sst variability in the two regions while benguela ninos peak in austral fall due to the angola benguela front being located furthest to the south and high interannual variability in coastal kelvin wave activity warm events at the equator are phase locked to austral winter when the thermocline is shallow perturbation experiments confirm the importance of remote forcing from the equator for sst variability off angola and demonstrate the leading role of wind stress in the generation of sst anomalies in the eastern tropical atlantic these wind stress variations are shown to be linked to fluctuations in the strength of the south atlantic anticyclone a connection that might be important with respect to the predictability of atlantic ninos

microseismic emissions from flowslide type movements in south wales abstract many of the unstable hillslopes of south wales have landslides that turn into flowslides over part of their tract the valley slopes at pant teg and glynrhigos are unstable as they possess the optimum requirements for slope failure they have probably been affected by repeated movements during the last 10 000 years significant acoustic emissions ae have been recorded from two landslide sites both subsequent to a major failure pant teg and during continuous movement glynrhigos four distinct types of ae have been recognised so far with frequencies in the 1 7 khz bandwidth with particular peaks at 1 2 2 0 4 2 4 9 5 5 and 6 5 khz the results indicate that there is a potential in developing a warning system for identifying increasing instability

the effectiveness of dendrogeomorphic methods for reconstruction of past spatio temporal landslide behaviour abstract dendrogeomorphic methods are in fact frequently used for spatio temporal landslide behaviour reconstruction however their real accuracies have not yet been deeply evaluated the purpose of this study is to evaluate the effectiveness and accuracy of tree ring based methods by comparing them with field monitoring data on landslide behaviours a total of 876 increment cores have been extracted from 219 p sylvestris individuals to reconstruct the past spatio temporal activity of the ubietova landslide 1977 the landslide re activation events recorded within the tree ring series of each tree have been spatially interpolated those data have been compared with the long term field monitoring based on the measured changes in the stabilized geodetic point positions in general the tree ring based spatio temporal landslide evolution revealed a higher landslide activity than the monitoring based one particularly in the lower part of the landslide however higher activity was recorded from the monitoring in the northern part of the upper half of the landslide while approximately 30 of the studied landslide area revealed highly similar normalized values based on both approaches the best fit between the results 80 was in areas with mean cumulative surface displacements of approximately 200 mm monitoring based results and mean event recurrence time of 14 5 years tree ring based results the potential sources of uncertainties that should be considered in future dendrogeomorphic research are the irregular spatial positions and spatial density of trees the physiology of the tree species the inertia of tree growth responses within tree ring sequences and the type of studied landslide

kinematic behaviour and velocity characteristics of a complex deep seated crystalline rockslide system in relation to its interaction with a dam reservoir abstract this paper presents the geometry kinematics and temporal deformation characteristics of a deep seated rockslide system the hochmais atemkopf situated above the gepatsch dam reservoir in northern tyrol austria results from surface and subsurface geological investigations and deformation monitoring indicate that the hochmais atemkopf rockslide system involves several sliding masses one on top of the other characterized by different velocity characteristics with displacements being greater for the shallower slide bodies during the initial impounding phases of the gepatsch reservoir uplift forces beneath the foot of the slope led to the activation of one of these shallower slide bodies moving it more than 10 m downslope in 2 years after continuous deceleration of the sliding mass the deformation rates reduced to about 2 to 4 cm per year these were found to show seasonal fluctuations that correlated with reservoir levels and drawdown conditions with induced slope accelerations peaking when reservoir levels were at their lowest this suggests in part a controlling mechanism based on seepage forces where reservoir drawdown drives the episodic rockslide deformation behaviour together the data and analyses presented demonstrate the importance of integrating detailed geology and monitoring data to derive a basic understanding of the kinematics and controlling mechanisms of a deep seated rockslide system in advance of undertaking comprehensive numerical modelling

role of tropical sst variability on the formation of subtropical dipoles abstractinterannual variations of sea surface temperature sst in the midlatitudes of the southern hemisphere play an important role in the rainfall variability over the surrounding countries by modulating synoptic scale atmospheric disturbances these are frequently associated with a northeast southwest oriented dipole of positive and negative sst anomalies in each oceanic basin referred to as a subtropical dipole this study investigates the role of tropical sst variability on the generation of subtropical dipoles by conducting sst nudging experiments using a coupled general circulation model in the experiments where the simulated sst in each tropical basin is nudged to the climatology of the observed sst the subtropical dipoles tend to occur as frequently as the case in which the simulated sst is allowed to freely interact with the atmosphere it is found that without the tropical sst variability the zonally elongated atmospheric mode in the mid to high latitudes called the antarctic oscillation

acoustic emission behaviour of dense sands interpretation of acoustic emission ae generated by particulate materials has to date been qualitative the objective of this study was to move the discipline towards quantitative interpretation

twelve year dynamics and rainfall thresholds for alternating creep and rapid movement of the hooskanaden landslide from integrating insar pixel offset tracking and borehole and hydrological measurements

seismic detection and evaluation of delta and turbidite sequences their application to exploration for the subtle trap energy conditions at the seaward edge of deltas allow their division into fluvial dominated wave dominated and tide dominated deltas each kind of delta has a distinct framework orientation and depositional pattern which results in a characteristic seismic reflection pattern fluvial dominated deltas are characterized by clinoform seismic reflection patterns which include oblique tangential complex oblique tangential sigmoid and complex sigmoid oblique seismic facies analysis can be used to define those facies which should contain sand wave dominated deltas are characterized by shingled seismic reflection patterns seismic facies analysis of this delta is not effective in identifying those facies which should be sand prone shingled reflections may be used in determining the possible location and depositional attitude of strandline sands tide dominated deltas have not yet been identified using seismic stratigraphic methods and therefore are not covered in this paper turbidite fans are sequences of sands and shales deposited in conjunction with and basinward of deltas or submarine canyons turbidite sands can be classified generally into channel and suprafan sands certain seismic events and reflection patterns occurring in various combinations may suggest the presence of turbidites these indicators include troughs submarine canyons mounds prograded fluvial dominated delta reflection patterns which vary in thickness and onlap offlap patterns on depositional slopes regional studies provide the best means of identifying and mapping depositional sequences examples from the north sea gulf coast and sacramento valley illustrate the geologic and geophysical expression of delta and turbidite sequences and their interrelations

acoustic emission sensing of pipe soil interaction full scale pipelines subjected to differential ground movements abstractthis paper presents the first full scale demonstration of the potential use of pipe soil interaction generated acoustic emission ae for early detection of buried pipe deformation full sc

experimental investigation on progressive deformation of soil slope using acoustic emission monitoring abstract the deformation process of soil slopes observed during a landslide can have progressive characteristics which can be quantified through acoustic emission ae monitoring a model test is designed based on the geological model of a translational landslide and experiments are conducted to reproduce the three stage deformation process of a soil slope the deformation process of progressive landslides is described using equations and an entire loading process is realized using a programmable logic controller plc the maximum velocity of a sliding body is measured to be approximately 6 mm s with the final displacement exceeding 210 mm the ae deformation and mechanical measurements of the entire process are compared to comprehensively evaluate the evolution behavior of progressive soil landslides the experiments demonstrate that ae rates can linearly quantify slope velocity as well as help quantify slope acceleration a copper tube and an aluminum tube are compared as different waveguides and the quantitative relationship between the ae and deformation obtained by the active copper waveguide is found to be more distinct the experiments also show that the acceleration of a slope can be effectively used as a discriminant index of progressive landslides which has the potential to be applied in field monitoring

an equatorial extratropical dipole structure of the atlantic nino abstractequatorial atlantic variability is dominated by the atlantic nino peaking during the boreal summer studies have shown robust links of the atlantic nino to fluctuations of the st helena subtropical anticyclone and benguela nino events furthermore the occurrence of opposite sea surface temperature sst anomalies in the eastern equatorial and southwestern extratropical south atlantic ocean sao also peaking in boreal summer has recently been identified and termed the sao dipole saod however the extent to which and how the atlantic nino and saod are related remain unclear here an analysis of historical observations reveals the atlantic nino as a possible intrinsic equatorial arm of the saod specifically the observed sporadic equatorial warming characteristic of the atlantic nino 0 4 k is consistently linked to southwestern cooling 0 4 k of the atlantic ocean during the boreal summer heat budget calculations show that the saod is largely driven by the surface net heat flux anoma

assessment of ground based monitoring techniques applied to landslide investigations a landslide complex in the whitby mudstone formation at hollin hill north yorkshire uk is periodically re activated in response to rainfall induced pore water pressure fluctuations this paper compares long term measurements i e 2009 2014 obtained from a combination of monitoring techniques that have been employed together for the first time on an active landslide the results highlight the relative performance of the different techniques and can provide guidance for researchers and practitioners for selecting and installing appropriate monitoring techniques to assess unstable slopes particular attention is given to the spatial and temporal resolutions offered by the different approaches that include real time kinematic gps rtk gps monitoring of a ground surface marker array conventional inclinometers shape acceleration arrays saa tilt meters active waveguides with acoustic emission ae monitoring and piezometers high spatial resolution information has allowed locating areas of stability and instability across a large slope this has enabled identification of areas where further monitoring efforts should be focused high temporal resolution information allowed the capture of s shaped slope displacement time behaviour i e phases of slope acceleration deceleration and stability in response to elevations in pore water pressures this study shows that a well balanced suite of monitoring techniques that provides high temporal and spatial resolutions on both measurement and slope scale is necessary to fully understand failure and movement mechanisms of slopes in the case of the hollin hill landslide it enabled detailed interpretation of the geomorphological processes governing landslide activity it highlights the benefit of regularly surveying a network of gps markers to determine areas for installation of movement monitoring techniques that offer higher resolution both temporally and spatially the small sensitivity of tilt meter measurements to translational movements limited the ability to record characteristic s shaped landslide movements at hollin hill which were identified using saa and ae measurements this high sensitivity to landslide movements indicates the applicability of saa and ae monitoring to be used in early warning systems through detecting and quantifying accelerations of slope movement

progradational sequences in miocene shoreline deposits southeastern caliente range california abstract an exceptionally well exposed marine nonmarine transition in middle miocene strata exists in the southeastern caliente range california about 50 individual progradational sequences form a succession that ranges in thickness from approximately 1000 m where predominantly nonmarine to more than 2500 m where predominantly marine paleogeographic evidence in basalt flows near the top of the succession and in overlying fluvial deposits indicates that these middle miocene strata were deposited across a north northwest trending shoreline a complete progradational sequence typically is several meters to a few tens of meters thick and includes strata that represent three intertonguing stratigraphic units individual sequences generally rest on a thin gravel deposit interpreted as a transgressive lag on an erosional surface the gravel is overlain by structureless siltstone or fine grained sandstone deposited at water depths where the rate of faunal mixing exceeded that of production of structures by physical processes these rocks grade upward into bedded fine sandstone deposited closer to shore where physical processes exceeded bioturbation crossbedded lenses of coarse sand or fine gravel in the upper part of this facies suggest the presence of fairly long period surface waves the bedded fine sandstone is sharply ove lain by a cross bedded coarse sandstone facies that is interpreted as a combined offshore bar rip channel surf zone assemblage cross strata dip dominantly offshore suggesting substantial deposition from rip currents a secondary shoreparallel mode of cross strata direction suggests longshore currents produced by surface waves from the northwest the crossbedded coarse grained sandstone grades upward into planar bedded medium grained sandstone that is interpreted as a beach foreshore this facies grades upward through structureless medium grained sandstone into nonmarine or lagoonal red and green mudstone of the caliente formation the middle miocene succession was deposited in a subsiding basin that was otherwise remarkably stable tectonically the position of the strand line differed no more than a few kilometers through a period of 1 to 3 m y the average duration of the transgressive regressive cycles a few tens of thousands of years together with their distribution in groups of three or four in the lower two thirds of the succession is consistent with the pattern of long term climatic cycles produced by periodicity of the earth s solar orbit and may be related to eustatic sea level changes attendant to the development of the antarctic ice cap changes in the pattern of progradation in the upper part of the succession and nearby basaltic eruptions may have been precursors to the onset of movement along th san andreas fault in this area 12 14 m y ago

bedforms and depositional sedimentary structures of a barred nearshore system eastern long island new york abstract the depositional sedimentary structures and textures of a single barred nearshore system on the atlantic coast of eastern long island new york were studied along seven shore normal transects data along these transects consisted of textural analysis of 160 sediment samples temporal bedform observations and 42 can cores for the analysis of sedimentary structures six sedimentary subenvironments were observed based on distinct combinations of sediment color and texture bedforms physical and biogenic sedimentary structures and benthic infaunal communities the shoreface environment is divided into the upper shoreface the longshore trough and the longshore bar the divisions of the inner shelf environment are the shoreface inner shelf transition the offshore and the coarse grained deposit the first five subenvironments are arranged in bands parallel to the shoreline whereas the coarse grained deposit occurs in patches across the inner shelf the location of fair weather wave base coinciding with a reduction in slope 3 0 0 3 from the shoreface to the inner shelf is characterized by the cessation of debris surge in the troughs of ripples the formation of a rust layer of microorganisms over the bedform surface and a sediment color change caused by an increase in organic detritus the sequence of bedforms and physical sedimentary structures observed in this system fits well with existing wave generated oscillatory flow regime models these models explain the observed sequences as a response to the degree of asymmetric flow created by shoaling waves distribution of biogenic structures and assemblages of infaunal organisms is influenced by the distance landward or seaward of fair weather wave base the overall relationships of this nearshore system can then be summarized as a hypothetical prograding stratigraphic sequence the entire sequence is underlain by organic rich bioturbated offshore deposits overlying the offshore is the planar laminated sediments of the transition grading upward from the transition are the cleaner planar laminated seaward slope deposits of the longshore bar above this is a distinct erosional surface indicating the base of the massive to cross laminated coarse sediments of the longshore trough capping the sequence are the cross to planar laminated clean sands of the upper shoreface and foreshore

integration of advanced monitoring and numerical modeling techniques for the complete risk scenario analysis of rockslides the case of mt beni florence italy on december 28 2002 a landslide occurred on the eastern flank of mt beni florence italy on a slope where jointed basalts and ophiolitic breccias overlie mesozoic limestones calcari a calpionelle formation the collapse was preceded by several forewarning signals the evolution of the slope deformation was the most important of them and its analysis was the starting point for a risk scenario assessment in fact during the management of the emergency period which began on april 13 2002 in effort to evaluate the actual extension of the landslide the distribution of the displacements within the mass its kinematical characteristics and its spatial and temporal evolution data obtained by means of geomechanical surveys laboratory analyses geotechnical investigations geophysical surveys seismic and gbinsar monitoring systems distometric and automatic and distinct element numerical modeling were integrated thus it has been possible to provide public authorities with all necessary information to plan suitable measures for risk management and reduction after the event the study was completed with a runout back analysis that highlighted successes and failures of the predictive investigations

annular modes in the extratropical circulation part i month to month variability the leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep zonally symmetric or annular structures with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 458 latitude the structure and dynamics of the southern hemisphere sh annular mode have been extensively documented whereas the existence of a northern hemisphere nh mode herein referred to as the arctic oscillation ao has only recently been recognized like the sh mode the ao can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields in this paper the structure and seasonality of the nh and sh modes are compared based on data from the national centers for environmental prediction national center for atmospheric research reanalysis and supplementary datasets the structures of the nh and sh annular modes are shown to be remarkably similar not only in the zonally averaged geopotential height and zonal wind fields but in the mean meridional circulations as well both exist year round in the troposphere but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave mean flow interaction midwinter in the nh and late spring in the sh during these active seasons the annular modes modulate the strength of the lagrangian mean circulation in the lower stratosphere total column ozone and tropopause height over mid and high latitudes and the strength of the trade winds of their respective hemispheres the nh mode also contains an embedded planetary wave signature with expressions in surface air temperature precipitation total column ozone and tropopause height it is argued that the horizontal temperature advection by the perturbed zonal mean zonal wind field in the lower troposphere is instrumental in forcing this pattern a companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades

simulations of the atmospheric response to south atlantic sea surface temperature anomalies abstract the sensitivity of the atmospheric circulation to sea surface temperature sst anomalies in the tropical and subtropical south atlantic ocean is studied by means of simulations with an atmospheric general circulation model gcm two types of prescribed sst anomalies are used motivated by previous analyses of data the first occurs during austral summers in association with a strengthening of the south atlantic convergence zone sacz and consists of cold sst anomalies over the subtropical south atlantic the second is the leading seasonally varying empirical orthogonal function of sst consisting of warm basin scale anomalies with maximum amplitude in the subtropics during january march and at the equator in june an ensemble of about 10 seasonal simulations is made using each type of anomaly focusing on the january march period in the first case and the january june seasonal evolution in the second during january march both experiments yield a statistically significant baroclinic response o

the use of surface monitoring data for the interpretation of landslide movement patterns the tessina landslide is a large seasonally active slope failure located on the southern slopes of mt teverone in the alpago valley of ne italy consisting of a complex system that has developed in tertiary flysch deposits the landslide which first became active in 1960 threatens two villages and is hence subject to detailed monitoring with high quality data being collected using piezometers inclinometers extensometers and through the use of a highly innovative automated electronic distance measurement edm system which surveys the location of a large number of reflector targets once every 6 h these systems form the basis of a warning system that protects the villages but they also provide a very valuable insight into the patterns of movement of the landslide in this paper analysis is presented of the movement of the landslide concentrating on the edm dataset which provides a remarkable record of surface displacement patterns it is proposed that four distinct movement patterns can be established which correspond closely to independently defined morphological assessments of the landslide complex any given block of material transitions through the four phases of movement as it progresses down the landslide with the style of movement being controlled primarily by the groundwater conditions the analysis is augmented with modelling of the landslide undertaken using the itasca flac code the modelling suggests that different landslide patterns are observed for different parts of the landslide primarily as a result of variations in the groundwater conditions the model suggests that when a movement event occurs displacements occur initially at the toe of the landslide then retrogress upslope

interannual and interdecadal variability of the south atlantic convergence zone interannual variations of the summertime january march atmospheric circulation over subtropical south america are examined during the period 1958 97 using the national centers for environmental prediction national center for atmospheric research reanalysis data it is found from an empirical orthogonal function analysis that an anomalous upper tropospheric large scale stationary eddy in the lee of the andes tends to accompany a dipole in anomalous vertical motion an anomalous cyclonic anticyclonic eddy accompanies an intensified diffuse south atlantic convergence zone sacz with anomalous descent ascent to the southwest the cold core equivalent barotropic vertical structure of the anomalous cyclonic eddy and the 200 hpa vorticity balance are both characteristic of a stationary rossby wave the tendency for the eddy to be advected downstream by the mean westerlies is compensated by meridional advection of planetary vorticity and stretching associated with vertical motion the anomalous cyclonic flow at low levels reinforces the thermally direct circulation associated with the sacz a weak funneling of submonthly rossby wave activity into this descent region is also identified the interannual time series of the eddy is significantly correlated with north south dipolar sea surface temperature sst anomalies over the southwest atlantic one standard deviation 200 hpa wind speed anomalies of up to 5 m s21 are accompanied by sst anomalies of up to 0 38c a near cyclic 15 yr component is identified which the authors corroborate from independent analyses of southwest atlantic ssts and river flows both are

the impact of enso on the south atlantic subtropical dipole mode abstractthe impact of el nino southern oscillation enso on the south atlantic subtropical dipole mode sasd is investigated using both observations and model simulations the sasd is the dominant mode of coupled ocean atmosphere variability in the south atlantic this study focuses on austral summer when both enso and sasd peak it is shown that negative sasd events are associated with central pacific el nino events by triggering the pacific south american wave train psa the latter resembles the third leading mode of atmospheric variability in the southern hemisphere psa2 and causes a weakening and meridional shift of the south atlantic subtropical high which then generates the negative sasd events on the other hand a strengthening of the south atlantic subtropical high related to central la nina teleconnections causes positive sasd events the results herein show that the psa2 triggered by central pacific enso events connects the tropical pacific to the atlantic this connection is absent f

does a monsoon climate exist over south america the climatology and the basic state of the summertime circulation and rainfall over south america are studied using assimilation products from the data assimilation system of goddard earth observing system 1 geos1 and satellite derived rainfall results indicate the existence of a regional summer monsoon circulation regime induced by strong diabatic heating over the subtropical south american highland centered at the altiplano plateau sensitivity of the results to the assimilation scheme is tested by comparing that with the national centers for environmental prediction ncep reanalysis and with satellite rainfall estimates results show general agreement between the model produced rainfall anomaly and the satellite estimates as well as consistency between the basic circulation features in the geos 1 and the ncep reanalyses a case study of 1989 90 south american summer monsoon sasm reveals the following characteristics 1 in late spring the onset of sasm is signaled by an abrupt merging of the upper tropospheric double westerly jets one in the subtropics and the other in the subpolar region into a single jet in the midlatitudes this is followed by the establishment of a vortex to the southeast of altiplano and occurrence of heavy precipitation over subtropical eastern brazil 2 during the mature phase of sasm the heavy rainfall zone moves over the altiplano plateau and the southernmost brazilian highland the fully established sasm features are the following a an enhancement of equatorial north atlantic trade wind which emanates from the sahara high and crosses the equator over the south american continent b a buildup of strong northwesterlies along the eastern side of the tropical andes and c development of the south atlantic convergence zone in the southernmost position with strong convective activity meanwhile the upper tropospheric return flow emerges from an anticyclone formed over the altiplano plateau crosses the equator and sinks over northwestern africa 3 the withdrawal of sasm in late summer is signaled by the resplitting of the midlatitude westerly jet at the same time the low level northwest monsoon flow diminishes reducing the moisture supply and leading to the termination of heavy precipitation over the subtropical highland results also show that the above mentioned characteristics of sasm are clearly linked to the tropospheric temperature changes over the central south american highland sensible versus latent heating over the highland are bound to play an important role in the evolution of sasm to provide further support of presence of a monsoon climate over south america sasm is compared and contrasted to the classic east asian summer monsoon easm many similar features including evolution characteristics between the two systems have been identified contrasting aspects of the sasm from the easm are also discussed it is pointed out that a number of monsoonal characteristics of the climate of south america such as the seasonal reversal of the low level wind become apparent only when the strong annual mean wind is removed based on the characteristic features and their evolution the authors conclude that a monsoon climate does exist over south america

tropical atlantic variability modes 1979 2002 part i time evolving sst modes related to west african rainfall abstract this work presents a description of the 1979 2002 tropical atlantic ta sst variability modes coupled to the anomalous west african wa rainfall during the monsoon season the time evolving sst patterns with an impact on wa rainfall variability are analyzed using a new methodology based on maximum covariance analysis the enhanced climate prediction center cpc merged analysis of precipitation cmap dataset which includes measures over the ocean gives a complete picture of the interannual wa rainfall patterns for the sahel dry period the leading ta sst pattern related to the atlantic el nino is coupled to anomalous precipitation over the coast of the gulf of guinea which corresponds to the second wa rainfall principal component the thermodynamics and dynamics involved in the generation development and damping of this mode are studied and compared with previous works the sst mode starts at the angola benguela region and is caused by alongshore wind anomalies it then propagates wes

use of bed form climb models to analyze geometry and preservation potential of clastic facies and erosional surfaces based on a combination of walther s law of facies and bed form climb theory we propose a model that explains how erosion surfaces and vertical sequences of clastic strata are preserved where deposition occurs in channelized or locally erosional environments including fluvial and submarine channel deposits barred beaches and transgressive coastlines the model considers both lateral and vertical migration of a scour surface and its associated depositional products as in studies of bed form climb we recognize subcritical critical and supercritical climb of scour surfaces relative to adjacent depositional forms for a given erosion surface the amount of underlying material removed is dictated by the climb angle of the erosion surface preservation of sequences also d pends on whether conditions were relatively variable or invariable one important conclusion of this study is the recognition of the bed form climb angle s control on the thickness of a sedimentary facies estimates of paleochannel depth or paleowater depth based on facies thickness can be made only if the climb angle is zero by combining depositional models of fluvial nearshore and offshore facies it is theoretically possible to model depositional systems such as deltas and passive continental margins potential applications are limited by several factors including influence of sea level climatic fluctuations on sedimentation and variable migration of facies or nonideal behavior or sedimentary environments in addition negative climb angles or climb angles less than horizontal can result in the removal of large amounts of material such negative climb angles may be caused by drops in eustatic sea level and lowering of base levels of drainage systems we believe that this heuristic model has considerable potential in helping sedimentologists and stratigraphers predict the consequences of facies mi ration

basal sliding and plastic deformation of a slow reactivated landslide in new zealand abstract the taihape landslide is a large deep seated translational rockslide in central north island of new zealand one of over 7000 large landslides mapped in the late neogene deposits of this area this study examined its patterns of movement using high temporal resolution high precision monitoring and explored the relationships between the movement and triggering mechanisms during the 30 year monitoring period movement was always extremely slow but included periods of faster and slower motion due to a combination of simultaneous basal sliding internal plastic deformation and seasonal soil shrinkage and swelling the data suggested that movement rate was not controlled by pore water pressure or any other monitored parameter intervals of more rapid movement appear to follow toe erosion that debuttress the landslide mass an example of which occurred following a flood in february 2004 that had a return period of about 100 years the high temporal and spatial frequency of the monitoring and the measurement precision of the instruments have allowed new insights into the complex movement patterns of deep seated slow moving rockslides the patterns of movement observed here and the techniques described to collect and analyse the data are applicable to many slowly moving landslides in new zealand and to those occurring in similar environments worldwide

variability in the south atlantic anticyclone and the atlantic nino mode sea surface temperature sst anomalies in the eastern equatorial atlantic are connected to modulations in the strength of the south atlantic subtropical high pressure system referred to as the south atlantic anticyclone saa using ocean and atmosphere reanalysis products we show here that the strength of the saa from february to may impacts the timing of the cold tongue onset and the intensity of its development in the eastern equatorial atlantic eea via anomalous tropical wind power this modulation of the timing and amplitude of the seasonal cold tongue development manifests as anomalous sst events peaking between june and august the timing and impact of this connection is not completely symmetric for warm and cold events for cold events an anomalously strong saa in february and march leads to positive wind power anomalies from february to june resulting in an early cold tongue onset and subsequent cold sst anomalies in june and july for warm events the anomalously weak saa persists until may generating negative wind power anomalies that lead to a late cold tongue onset as well as a suppression of the cold tongue development and associated warm sst anomalies mechanisms by which saa induced wind power variations south of the equator influence eea sst are discussed including ocean adjustment via rossby and kelvin wave propagation meridional advection and local intraseasonal wind variations

a physical basis for the interannual variability of rainfall in the sahel a major factor in rainfall variability over sahelian west africa is the latitudinal location of the tropical rainbelt when it is displaced abnormally far northward the sahel experiences a wet year an anomalous southward displacement results in drought in this paper we examine the question of what controls the location during the boreal summer hypothesizing that inertial instability plays a role an analysis of surface pressure and temperature fields wind fields divergence and vertical motion show that the criteria for inertial instability are satisfied in wet augusts but not in dry ones the key determinant appears to be the surface pressure gradient between the continent and the equatorial atlantic when this is large inertial instability results in the development of a low level westerly jet the presence of this jet enhances the horizontal and vertical shear and displaces the african easterly jet northwestward associated with this situation is strong vertical motion over the sahel and subsidence over the guinea coast producing dry conditions over the latter the result is a rainfall dipole one of two major modes of variability over west africa important factors include sea surface temperatures ssts in the equatorial atlantic and pressure in the south atlantic the first of these factors suggests a link with the atlantic nino mode of tropical atlantic variability while the second suggests a possible link with the pacific and the extratropical south atlantic overall our study relates the well known sst influence on sahel rainfall to atmospheric dynamics over the continent copyright 2007 royal meteorological society

temperature dependent residual shear strength characteristics of smectite bearing landslide soils this paper presents experimental investigations regarding the effect of temperature on the residual strength of landslide soils at slow to moderate shearing velocities we performed ring shear tests on 23 soil samples at temperatures of 6 29 c the test results show that the shear strength of smectite rich soils decreased when temperatures were relatively low these positive temperature effects strength losses at lower temperatures observed for smectite bearing soils are typical under relatively slow shearing rates in contrast under relatively high shearing rates strength was gained as temperature decreased as rheological properties of smectite suspensions are sensitive to environmental factors such as temperature ph and dissolved ions we inferred that temperature dependent residual strengths of smectitic soils are also attributed to their specific rheological properties visual and sem observations of ca bentonite suggest that slickensided shear surfaces at slow shearing rates are very shiny and smooth whereas those at moderate shearing rates are not glossy and are slightly turbulent indicating that platy smectite particles are strongly orientated at slow velocities the positive temperature effect is probably due to temperature dependent micro friction that is mobilized in the parallel directions of the sheet structure of hydrous smectite particles on the contrary the influence of micro viscous resistance which appears in the vertical directions of the lamination is assumed to increase at faster velocities our results imply that if slip surface soils contain high fractions of smectite decreases in ground temperature can lead to lowered shear resistance of the slip surface and trigger slow landslide movement

quartzose turbidites of the accretionary complex of barbados ii variations in bedding styles facies and sequences abstract barbados provides the only subaerial exposures of the barbados ridge an accretionary complex lying outboard of the lesser antilles volcanic arc within nine measured sections of quartzose turbidites five major types of sequences are recognized 1 1 progradational sequences basin plain outer fan of uniformly fine grained flat based base absent turbidites that thicken upward and gradually become coarser grained and base present at the top of the sequence 2 2 a single rejuvenation rapid progradational sequence was identified as an abrupt progradational sequence above abandoned lobe deposits and is not characterized by stacked well developed upward thickening successions as many progradational sequences are 3 3 channelized successions of coarse grained base present turbidites arranged in packets 5 20 or 50 140 m thick which are midfan and inner fan deposits respectively the distinction between predominance of base present and base absent turbidites seems to correspond with the interpreted change from midfan channelized to outer fan sheet flow deposition 4 4 one example of a major retrogradational sequence of midfan deposits above inner fan sandstones has been found on barbados minor sequences of facies retrogradation are relatively common in the outer fan environment where upward thinning sandstone beds overlie upward thickening units to define symmetric sequences 5 5 abandonment successions are major as indicated by massive accumulations of mudstone minor as indicated by abrupt reversals of upward thickening trends in outer fan lobe deposits and cryptic where indicated by thick 4 m bioturbated zones of massive sandstone

towards a complete understanding of the triggering mechanism of a large reactivated landslide in the three gorges reservoir abstract the primary aim of this study is to research the characteristics of a slide motion and its relationships with environmental triggers with reference to the quchi landslide which is a large slow moving reactivated landslide in the three gorges reservoir region since 2006 this instability has been involved in a slow moving process with clearly visible signs ground fissures cracking of houses and road the landslide consists of 18 mm3 rock masses threatening quchi town and a road that is crucial for local transportation for civil protection purposes a continuous monitoring system has been put into use since 2009 combining four years of meteorological and hydrological data with gps displacement measurements and in situ observations allows a detailed identification of the key processes involved the deformation is thought to be closely related to precipitations and fluctuating reservoir levels slope movements have a highly distinctive pattern that is characterized by high deformation starting in june and lasting into september when the reservoir level drops and rainfall increases followed by a rapid transition to constant deformation until the next wet season in order to investigate in detail the influences of rainfall and fluctuating water levels on the hydromechanical behavior of the landslide a series of two dimensional numerical simulations are performed using the universal distinct element code udec the modeling reveals that precipitation mainly mobilizes the slope materials on the upper part of the slope while the other trigger factor fluctuating water levels destabilizes the foot of the slope into a multistage failure with a remarkable retrogressive evolution the slide is most likely to collapse in a complex pattern characterized by en masse sliding on the upper part of the slope and a retrogressive rupture at its foot

influence of the south atlantic ocean dipole on west african summer precipitation abstract this paper demonstrates a causal link between the air sea phenomenon referred to as the south atlantic ocean sao dipole saod and the interannual variability of precipitation over west africa during the boreal summer monsoon rainy season in which most of the annual rainfall is recorded using an array of observational datasets analyses show that positive precipitation anomalies exceeding 40 mm month 1 over most locations at the guinea coast are associated with the positive phase of the saod which is characterized by warm sea surface temperature anomalies sstas in the northeastern part of the sao or the northeast pole nep that is the atlantic nino sector and cool ssta in the southwestern part southwest pole swp off the argentina uruguay brazil coast on the other hand interannual variability in the sahel is closely connected to the west african summer monsoon and the atlantic nino the results of this study reveal that the well known influence of the atlantic nino on guinea coast pre

atmosphere ocean coupled variability in the south atlantic abstract the climate variability of the south atlantic region is determined from 40 yr 1953 92 of comprehensive ocean atmosphere data set monthly sea surface temperature sst and sea level pressure slp data using the empirical orthogonal function eof and the singular value decomposition svd analysis methods the eof method is applied to each field separately whereas the svd method is applied to both fields simultaneously the significance of the atmosphere ocean interaction is revealed by a strong resemblance between individual eof and coupled svd modes of sst and slp the three leading modes of coupled variability on interannual and interdecadal timescales are discussed in some detail the first coupled mode which accounts for 63 of the total square covariance represents a 14 16 yr period oscillation in the strength of the subtropical anticyclone accompanied by fluctuations of a north south dipole structure in the sst the atmosphere ocean coupling is strongest during the southern summe

interactions between sea surface temperature over the south atlantic ocean and the south atlantic convergence zone 1 interactions between the sea surface temperature sst over the south atlantic ocean 40 s equador and the south atlantic convergence zone sacz were studied through numerical experiments with an atmospheric general circulation model agcm and an ocean general circulation model ogcm the agcm experiments showed that warm sst anomalies over the south atlantic tend to intensify the sacz and shift it northward while cool sst anomalies over the south atlantic tend to weaken the sacz the ogcm experiments on the other hand showed that the intensification of the sacz contributes to cool the underlying ocean through the reduction of incident shortwave solar radiation causing the appearance of cold sst anomalies or the weakening of pre existing warm sst anomalies the most important finding in this work was the predominance of the cloud shortwave sst negative thermodynamic feedback between the atmosphere and the ocean over the southwest tropical atlantic this is one order of magnitude larger than the dynamic feedback associated with ekman pumping the latter was verified only during strong sacz events the results suggest that negative sst anomalies often observed underlying the sacz represent an ocean response to atmospheric forcing

morphology structure and kinematics of a rainfall controlled slow moving andean landslide peru the large slow moving landslide of maca is located in the upper colca valley southern peru a region characterized by a well pronounced rainy period and intense and recurrent sustained seismicity the landslide developed in deep lacustrine deposits has recently accelerated threatening the maca village this work aims at understanding the rupture mechanism and the causes of the recent landslide reactivation acceleration we present a multidisciplinary characterization of the maca landslide that includes i geological and morphological mapping in the field ii remote sensing analysis using an historical aerial photograph of 1955 and the pleiades satellite images 2013 iii global positioning system gps including time series of surveys over 13 years and continuous measurements over 14 months iv a geophysical campaign with deep electrical resistivity tomography profiles acquired across the landslide mass our study shows that this 60 mm3 landslide which can be classified as a clay silt compound landslide moved by 15 m between 2001 and 2014 with a large inter annual velocity variation up to a factor of 500 depending on the rainfall intensity we suggest that these dramatic changes in velocity are the result of the combination of a threshold mechanism and the short intense rainy season in peru this study reveals three main driving factors acting at different timescales i over several decades the river course has significantly changed causing the maca landslide reactivation in the 1980s due to the erosion of its toe ii at the year scale a minimum amount of rainfall is required to trigger the motion and this amount controls the landslide velocity iii transient changes in slide velocity may occur anytime due to earthquakes this study particularly highlights the non linear behaviour of the motion with rainfall copyright 2016 john wiley sons ltd

diverse slow slip behavior at the hikurangi subduction margin new zealand 1 the installation of a continuous gps cgps network in new zealand since 2002 has enabled the discovery of 15 slow slip events at the hikurangi subduction margin our analysis and interpretation of the cgps data reveal a marked diversity in characteristics of slow slip events sses in the north island with durations varying from 6 days to 1 5 years equivalent moment release between mw 6 3 7 2 and recurrence intervals of repeating sses on the order of 2 years to more than 5 years the duration and magnitude characteristics of hikurangi sses appear to be related to the depth where they occur the deepest longest duration and largest sses occur at the southern hikurangi margin near the downdip limit of deep down to 40 km depth strong interseismic coupling the shallowest shortest duration smallest and most frequent sses occur at the northern and central hikurangi margin near the downdip limit of unusually shallow 10 15 km depth interseismic coupling the direction of slip on the interface in the hikurangi sses is consistent with slip partitioning at the hikurangi subduction margin we also show that moment accumulation rates on the interface for the time periods between sses are 40 higher than for the period of more than a decade averaging through the sses indicating that sses compose a major portion of the overall moment release budget of the hikurangi subduction interface

using advanced insar techniques to monitor landslide deformations induced by tunneling in the northern apennines italy synthetic aperture radar sar interferometry insar is used to make measurements of small surface displacements in different situations including ground settlement landslides and excavations we document the deformation history of four dormant deep seated landslides in the northern apennines of italy that were reactivated by the excavation of a double road tunnel the tunnel is part of a larger infrastructure project that involves the improvement of the a1 highway which connects bologna and florence the excavation of the tunnel under the landslides basal shear surfaces started in 2011 and with the advance of the tunnel front deformation began to occur causing damages to homes and infrastructures the tunnel passes under the small villages of ripoli and santa maria maddalena the deformation slowed down after the tunnel was completed in november 2014 and low surface displacement rates were registered for the period between october 2014 and june 2016 we show the results of an insar analysis designed to measure surface movements between 2003 and 2016 the insar displacements are derived from the envisat cosmo skymed and sentinel 1 datasets and cover the main construction phase of the tunnel 2011 2015 a detailed geological and geomorphological mapping of the slope is developed based on the field evidence and on the spatial pattern of surface deformation provided by our insar analysis together with the map a new conceptual geological model of the slope in tectonically sheared and weathered flysch is presented the satellite insar data show good agreement with available ground based monitoring data that include inclinometer and gps measurements while small differences occur with respect to deformation time series obtained from a ground based insar instrument in particular the insar results for the x band data of cosmo skymed demonstrate the close relationship between the position of the excavation front and the displacement rates of previously dormant landslide deposits conversely the concurrent rainfall does not appear to significantly influence the observed behavior and if any had only a minor influence on the displacement history of the investigated landslides

mechanisms limiting the southward extent of the south american summer monsoon an intermediate atmospheric model coupled with a simple land surface model and a mixed layer ocean model is used to examine effects that determine the southward extension of summer precipitation over south america the extent of the continental convergence zone is mainly determined by two mechanisms which we term ventilation and the interactive rodwell hoskins mechanism ventilation refers to the import into south america of low moist static energy air from the cooler ocean primarily the pacific in the interactive rodwell hoskins mechanism rossby wave induced subsidence to the west of the diabatic heating interacts with the convection zone because of the shape of south america the interactive rodwell hoskins mechanism is of comparable importance to ventilation soil moisture feedback also helps limit poleward movement of the continental convergence zone but its effect is relatively weak compared to the above two effects the characteristic northwest southeast tilt of the continental convergence zone appears to be due to a combination of ventilation and the interactive rodwell hoskins mechanism

flow units connectivity and reservoir characterization in a wave dominated deltaic reservoir meren reservoir nigeria the meren e 01 agbada formation middle miocene reservoir offshore nigeria consists of a lower progradational shoreface succession terminated by a minor sequence boundary overlain by a progradational and retrogradational shoreface succession deposition occurred in a wave dominated delta front as indicated by the presence in core of hummocky cross beds slumped units and turbidites eight flooding surfaces were correlated and isopach maps sandstone quality trend maps and mudstone quality trend maps were constructed for each parasequence this work revealed a complex reservoir architecture characterized by shoreface clinoforms and a history of progradation and retrogradation cycles three different three dimensional geological characterizations of the e 01 reservoir were built a geostatistical model that used only well data a more geologically complex facies based model that used the sandstone quality trend maps in addition to well data and the most geologically complex sequence stratigraphic model that used mudstone quality trend maps in addition to the above data the three models were analyzed in terms of sandstone continuity and connectivity to hypothetical injector and producer wells only the sequence stratigraphic model predicted significant vertical compartmentalization through tortuosity generated by flooding surface mudstones waterflood fluid flow simulation of a downdip sector of the geologic models predicts similar recovery for the three models but a significantly different distribution of unswept oil only the sequence stratigraphic model identified parasequences with abundant unswept oil that are large enough to be economic infill prospects history matched full field fluid flow simulations verify both the reservoir compartments predicted by the sequence stratigraphic model and infill targets

on the triggering of benguela ninos remote equatorial versus local influences 1 the relative importance of remote and local influences in the development of benguela ninos is examined using observations and a coupled general circulation model capable of simulating interannual variability in the tropical atlantic while previous studies have emphasized the role of equatorially excited kelvin waves the present study finds that meridional wind anomalies along the southwest african coast contribute substantially both observations and model output indicate that sea surface temperatures along the southwest african coast respond rapidly to changes in meridional wind stress these wind anomalies form part of a basin scale weakening of the subtropical anticyclone that extends to the equator as the weakening begins three months before the peak of the event it might have some predictive potential results also indicate that the close correlation between benguela and atlantic ninos in observations might result from the large spatially coherent wind stress anomalies associated with the weakened anticyclone

understanding the kinematic behavior of the active gascons rockslide from in situ and satellite monitoring data abstract the monitoring of the 410 000 m3 coastal gascons rockslide began in 2009 this paper presents and analyzes combined in situ and satellite based monitoring data to interpret the kinematic behavior of the slide and the evolution of the rockslide and the possible mechanisms that can lead to an accelerating phase of movement the available data are 1 relative displacements measured by thirteen crackmeters and manually with an extensometer tape 2 absolute displacements obtained from inclinometers and vertical shape accelerometer arrays in boreholes total station surveys and satellite based point target analysis insar pta 3 the settlement of the railway ballast monitored by two horizontal shape accelerometer arrays 4 groundwater pressures from nine vibrating wire piezometers and 5 weather conditions the study indicates that the role of water on displacements varies spatially within the rockslide the rockslide s kinematic behavior enables us to develop evolution scenarios of the rockslide which could be useful to conduct a risk analysis this leads to the identification of critical zones for railroad safety the unique set of monitoring data helps to elucidate the complexity of the rockslide s behavior

a multi model approach to the atlantic equatorial mode impact on the west african monsoon this paper is focused on the west african anomalous precipitation response to an atlantic equatorial mode whose origin development and damping resembles the observed one during the last decades of the xxth century in the framework of the amma eu project this paper analyses the atmospheric response to the equatorial mode using a multimodel approach with an ensemble of integrations from 4 agcms under a time varying equatorial sst mode the guinean gulf precipitation which together with the sahelian mode accounts for most of the summer west african rainfall variability is highly coupled to this equatorial atlantic sst mode or atlantic nino in a previous study done with the same models under 1958 1997 observed prescribed ssts most of the models identify the equatorial atlantic sst mode as the one most related to the guinean gulf precipitation the models response to the positive phase of equatorial atlantic mode warm ssts depicts a direct impact in the equatorial atlantic leading to a decrease of the local surface temperature gradient weakening the west african monsoon flow and the surface convergence over the sahel

effects of the foot evolution on the behaviour of slow moving landslides the paper presents a time dependent 2d numerical model which has been developed with the purpose of highlighting the effects of the slope foot evolution on the behaviour of slow moving landslides the model allows to quantitatively analyse how foot mass variations can influence the stability and the movement rates of the landslide the landslide body is modelled as composed of two rigid blocks sliding on two different planes and interacting through a common boundary which position is assumed fixed during the analysis a finite difference approach is used to discretize the time for each time increment changes in model parameters are allowed including variations in shearing resistances groundwater level and block masses in order to simulate foot erosion during each iteration the overall stability of the system is checked computing the safety factor assuming that the percentage of mobilized shear strength is the same for the three surfaces if the system is not stable or if it is not at rest the velocity of the system is computed solving the momentum equations for the two blocks taking into account destabilising and resisting forces the mechanical interaction between the blocks and viscous components computed velocities are iteratively used to compute mass accumulation at the foot which in turn results in a change of the stability condition of the system examples are provided in order to highlight the roles of the model parameters finally the application to a real landslide vallcebre spain is presented which shows the advantage of considering the foot mass in the analysis of the displacement trends and the possibility to take into account the foot erosion in the long term behaviour of the slope

three dimensional displacements of a large volcano flank movement during the may 2010 eruptions at pacaya volcano guatemala although massive flank failure is fairly common in the evolution of volcanoes measurements of flank movement indicative of instability are rare here 3 d displacements from airborne radar amplitude images derived using an amplitude image pixel offset tracking technique show that the west and southwest flanks of pacaya volcano in guatemala experienced large 4 m discrete landsliding that was ultimately aborted pixel offset tracking improved measurement recovery by nearly 50 over classic interferometric synthetic aperture radar techniques providing unique measurements at the event the 3 d displacement field shows that the flank moved coherently downslope along a complex failure surface involving both rotational and along slope movement notably the lack of continuous movement of the slide in the years leading up to the event emphasizes that active movement should not always be expected at volcanoes for which triggering factors e g magmatic intrusions and eruptions could precipitate sudden major flank instability

rotational translational landslides in the neogene basins at the northeast margin of the tibetan plateau abstract rotational translational landslides are common in neogene basins throughout the world and are of high risk to the public to understand the mechanism of rotational translational failure the spatial distribution and deformation of rotational translational landslides in the northeast of the tibetan plateau are investigated in this study the spatial distribution of these landslides is dependent on the regional tectonics and geomorphology crustal stresses and lithological properties the rotational translational landslides are concentrated in the neogene mudstone basins and the intensities of these landslides are observed to gradually decrease from the hinterland of the plateau to the marginal basins the bedding parallel shear zones within the location of the rotational translational landslides are present in the overconsolidated neogene mudstones with high clay content nearly horizontal tectonic stresses and erosion cause the formation of horizontal shear stresses in the sliding masses in this stress environment materials with low internal friction angle

in situ monitoring platform and preliminary analysis of monitoring data of majiagou landslide with stabilizing piles abstract reservoir landslide evolution is a complex multi fields dynamic process which involves the interaction of the seepage field stress field displacement field and temperature field after installing the stabilizing structure into landslide the landslide and stabilizing structure will establish the landslide stabilization system and lead to a more complex multi fields evolution process under the reservoir operation to study this complex problem this paper designs and establishes a comprehensive in situ multi fields information monitoring platform which has been installed on majiagou landslide in three gorges reservoir area the multi fields information monitoring platform has four components the landslide stabilization system the in situ multi field monitoring system the data transmission and receiving system and the database management system the landslide stabilization system includes majiagou landslide and two experimental reinforced concrete piles the in situ monitoring system consists of landslide surface deformation monitoring system experimental piles monitoring system and boreholes monitoring system the landslide surface deformation monitoring system includes gps stations and fiber lines the experimental pile monitoring system consists of earth pressure cells around piles stress and strain gauges on steel bars and strain and temperature fiber sensors in piles the borehole monitoring system includes boreholes with inclinometers water pressure and water level gauges fiber sensors therefore the in situ monitoring system can monitor the seepage stress displacement and temperature fields in the landslide as well as the force and deformation in the experimental piles currently the data transmission and management system is under construction and will be finished soon current monitoring results show that the landslide moves along three slip surfaces and the deformation of the experimental piles is influenced by reservoir operation this platform can provide multi fields data for scholars to study the evolution of landslide stabilization system

dominant modes of variability in the south atlantic a study with a hierarchy of ocean atmosphere models using an atmosphere model of intermediate complexity and a hierarchy of ocean models the dominant modes of interannual and decadal variability in the south atlantic ocean are studied the atmosphere simplified parameterizations primitive equation dynamics speedy model has t30l7 resolution the physical package consists of a set of simplified physical parameterization schemes based on the same principles adopted in the schemes of state of the art agcms it is at least an order of magnitude faster whereas the quality of the simulated climate compares well with those models the hierarchy of ocean models consists of simple mixed layer models with an increasing number of physical processes involved such as ekman transport wind induced mixing and wind driven barotropic transport finally the atmosphere model is coupled to a regional version of the miami isopycnal coordinate ocean model micom covering the south atlantic with a horizontal resolution of 1 and 16 vertical layers the coupled modes of mean sea level pressure and sea surface temperature simulated by speedy micom strongly resemble the modes as analyzed from the ncep ncar reanalysis indicating that this model configuration possesses the required physical mechanisms for generating these modes of variability using the ocean model hierarchy the authors were able to show that turbulent heat fluxes ekman transport and wind induced mixing contribute to the generation of the dominant modes of coupled sst variability the different roles of these terms in generating these modes are analyzed variations in the wind driven barotropic transport mainly seem to affect the sst variability in the brazil malvinas confluence zone the spectra of the mixed layer models appeared to be too red in comparison with the fully coupled speedy micom model due to the too strong coupling between sst and surface air temperatures sats resulting from the inability to advect and subduct sst anomalies by the mixed layer models in speedy micom anomalies in the southeastern corner of the south atlantic are subducted and advected toward the north brazilian coast on a time scale of about 6 yr

quantification of landslide velocity from active waveguide generated acoustic emission acoustic emission ae has become an established approach to monitor stability of soil slopes however the challenge has been to develop strategies to interpret and quantify deformation behaviour from the measured ae ae monitoring of soil slopes commonly utilizes an active waveguide that is installed in a borehole through the slope and comprises a metal waveguide rod or tube with a granular backfill surround when the host slope deforms the column of granular backfill also deforms and this generates ae that can propagate along the waveguide results from the commissioning of dynamic shear apparatus used to subject full scale active waveguide models to simulated slope movements are presented the results confirm that ae rates generated are proportional to the rate of deformation and the coefficient of proportionality that defines the relationship has been quantified e g 4 4 105 for the angular gravel examined it is demonstrated that slope velocities can be quantified continuously in real time th

characteristics of a pennsylvanian ravinement surface abstract a transgressive ravinement surface is documented above the mary lee coal zone of the lower pennsylvanian pottsville formation black warrior basin northwestern alabama this ravinement surface separates an underlying non marine regression sequence from an overlying marine one and is marked by a thin ravinement bed two types of ravinement beds are identified 1 a mudstone bed with an autochthonous pelecypod and brachiopod assemblage and 2 a sandstone bed with an autochthonous zoophycos and an allochthonous trilobite crinoid brachiopod assemblage under a subcritical condition in which the shoreface angle is greater than the gradient of coastal areas gradual rise of sea level causes erosion of the existing shoreface landward and upward migration of the shoreface has two genetic consequences 1 the formation of a ravinement surface consisting of a series of erosional surfaces and 2 the deposition of ravinement beds the sediments of which are controlled by the properties of the eroded shoreline the areal distribution of the two types of the ravinement beds represents a more than 60 km retreat of the shoreline in response to a long term change of sea level the recognition of the pennsylvanian ravinement surface not only provides a correlative surface for coal bearing rocks but also documents the basinal transgressive histories not previously recognized

atmospheric response to south atlantic sst dipole 1 recent analyses of historical data and output of numerical models have suggested a dipolar mode of decadal variability in the south atlantic in this work the the atmospheric response to such anomalous sst dipole in the south atlantic is investigated with a numerical model the results show a deep baroclinic response over the equatorward pole and a shallow equivalent barotropic response over the poleward pole the baroclinic response is strongest during the austral summer it affects the meridional circulation over the tropical atlantic with anomalous downward motion north of the itcz and anomalous ascending motion southward of it resulting in a southward shift of the itcz the itcz response is enhanced due to a positive feedback induced by anomalous low level convergence of moisture changes in cloud cover counteract the variations in latent heat flux north of the itcz thereby prohibiting the generation of an ssta of opposite sign as suggested by the wind evaporation sst wes feedback

on pore water pressure variations causing slide velocities and accelerations observed in a seasonally active landslide individual block displacements continuously recorded in spring 1987 in a landslide in the french alps are strongly affected by rain and dry spells although a viscous component is present in the sliding mechanism variation of the plastic strength characteristics is necessary to explain the controlled sliding a stick slip movement behaviour and a diurnal variation in slide rate attributed to the diurnal variation in evapotranspiration were recorded the observed numerous accelerations and decelerations of the blocks movements are attributed to small variations in pore pressure these variations are explained and their magnitude is calculated starting from limit equilibrium increases of pore water pressure smaller than 0 1 k pa are sufficient to provoke the maximum recorded acceleration and velocity for a block of 2000 tons in weight

kinematics of a giant slow moving landslide in northwest china constraints from high resolution remote sensing imagery and gps monitoring abstract slow moving landslides generally are long lived and characterized by continuous movement with some fluctuation in sliding rate following changes of environmental factors such as rainfall and earthquake analysis on kinematics of this type of landslide is essential for understanding its mechanism and identifying causal factors controlling its movement behavior this paper presents a study on kinematics of a giant slow moving landslide in northwest china called the xieliupo landslide which is about 72 10 6 m 3 in volume and has been slowly moving for more than 100 years this study is conducted using archival high resolution remote sensing images from multi sources over a period about 43 years and the data from 15 month gps monitoring six sets of multi source remote sensing images in 1969 1971 2004 2008 2010 and 2012 with spatial resolution higher than 2 5 m were used and gps monitoring data were recorded from september 2012 to december 2013 obvious geomorphologic changes identified from the images in 1971 and 2004 confirm that this landslide did move slowly in the past quantitative analysis reveals that movement of the landslide was persistent and behaved in a block by block mode with the greatest and the least velocities in its middle and lower parts respectively distance measurement between the homologous point pairs on the orthorectified images in 2005 2010 and 2012 indicates that annual ground displacement of the landslide ranged from 0 52 m to 6 54 m in the seven years gps monitoring data shows that the landslide ground displacement in the 15 months varied from 0 49 m to 2 91 m and annually between 0 39 m and 2 33 m with a rather uniform movement pattern as identified using the remote sensing images gps monitoring results also reveal that the landslide movement is intermittent inter annually it is further discussed that movement behavior of the landslide is largely controlled by its topography with great influence of the active fault along its left hand flank and river erosion at its toe rainfall may affect inter annual movement behavior of the landslide

application of sequence and genetic stratigraphic concepts to carboniferous coal bearing strata an example from the black warrior basin usa carboniferous strata provide an excellent example on which to test the application of genetic stratigraphic and sequence stratigraphic concepts both approaches are employed in the evaluation of the coal bearing strata of the black warrior basin south eastern usa bounding hiatal surfaces have been recognized in the succession of rock that includes the mary lee coal zone within the framework of genetic stratigraphy one genetic sequence has been identified comprised of offlap progradational and aggradational facies and onlap aggradational and transgressive facies components seven parasequence sets have been delimited according to the concepts of sequence stratigraphy these have been ascribed to transgressive highstand and shelf margin systems tracts the identification of components of these contrasting frameworks provide the basis for evaluating other carboniferous strata

pliocene exhumation and landscape evolution of central north island new zealand the role of the upper mantle 1 mudstone porosity analyses show that over 2 km of exhumation has occurred in central north island new zealand since 5 ma this combined with a coeval surface uplift of 500 m indicates a maximum 2 5 km of rock uplift in central north island the magnitude and wavelength 400 km of the rock uplift is similar to some topographic doming observed in continental areas associated with mantle upwelling yet central north island is recognized as a region of back arc extension marine terraces 100 150 km from the center of maximum exhumation show uplift rates of 0 2 0 3 mm yr 1 consistent with about 1 km of exhumation if averaged over 4 5 myr which compares well with mudstone porosity analyses seismic attenuation and slow pn velocities indicate that a thermal anomaly in the upper mantle is the source of this rock uplift the rock uplift may be explained by the replacement of a 100 km thick mantle lid by asthenosphere with a density 66 kg m 3 less than the lid about half this density contrast can be explained by thermal expansion and the rest is ascribed to partial melts in the upper mantle southward migration for the locus of maximum rock uplift is consistent with the zone of maximum incision erosion being 50 km south of the southernmost volcano such a migration is in keeping with other geological markers of volcanic and thermal phenomena and further strengthens the link of landscape evolution at active continental margins with processes in the mantle

seismological aspects of the 1989 1990 eruption at redoubt volcano alaska the materials failure forecast method ffm with rsam and ssam seismic data abstract seismic activity during the december 1989 to april 1990 eruption of redoubt volcano alaska has been tracked by the alaska volcano observatory using real time seismic amplitude measurement rsam and seismic spectral amplitude measurement ssam systems with up to five stations data consist of 10 minute averages of the absolute amplitudes of seismometer output these data have been used to test in hindsight the materials failure forecast method ffm which attempts to define the time of eruption with a time series for precursory phenomena whose rate of change accelerates measurably before events practical application of the method emphasizes inverse rate plots both for early detection of signal emergent from background and for event forecasting eruption windows are determined by graphical or numerical extrapolation of the inverse rate trend and by intersection of a data envelope reflecting data scatter and consistency with an empirical critical rate near the time of eruption prior to the dome destroying eruption of january 2 rate changes were of sufficient consistency duration and intensity for a qualitative or quantitative ffm predictive analysis using either rsam or ssam signal to noise ratio was high for both rsam or ssam data sets and ffm analyses could have provided useful support for decision making following january 2 in association with a rapid succession of dome collapse eruptions signal strength diminished and rsam signal to noise ratio declined the most distinct patterns on rsam reflected noise rather than signal and forecasting exclusively based for rsam would have been misleading by eliminating the noise in excluded frequencies an enhanced signal to noise ratio was generally produced by ssam for banded frequencies near 2 hz after january 2 only ssam exhibited signal to noise ratios suitable for ffm analysis inverse ssam plots could have been informative for early detection of precursory long period seismicity the prospect of combining the ffm approach with spectral amplitudes in selected frequencies offers considerable promise

deformation responses of slow moving landslides to seasonal rainfall in the northern apennines measured by insar abstract slow moving landslides are widespread geomorphological features in the northern apennines of italy where they represent one of the main landscape forming processes the lithology of the northern apennines fold and thrust belt is characterized by alternations of sandstone siltstone and clayshales also known as flysch and clay shales with a chaotic block in matrix fabric which are often interpreted as tectonic or sedimentary melanges while flysch rocks with a high pelitic fraction host earthslides that occasionally evolve into flow like movements earthflows are the dominant landslide type in chaotic clay shales in the present work we document the kinematic response to rainfall of landslides in these different lithologies using radar interferometry the study area includes three river catchments in the northern apennines here the mediterranean climate is characterized by two wet seasons during autumn and spring respectively separated by dry summers and winters with moderate precipitation we use sar imagery from the x band satellite cosmo skymed and from the c band satellite sentinel 1 to retrieve spatial displacement measurements between 2009 and 2016 for 25 landslides in our area of interest we also document detailed temporal and spatial deformation signals for eight representative landslides although the insar derived deformation signal is only well constrained by our dataset during the years 2013 and 2015 in spring 2013 long enduring rainfalls struck the study area and numerous landslide reactivations were documented by the regional authorities during 2013 we measured higher displacement rates on the landslides in pelitic flysch formations compared to the earthflows in the clay shales slower mean velocities were measured on most landslides during 2015 we analyse the temporal deformation signal of our eight representative landslides and compare the temporal response to precipitation we show that earthslides in pelitic flysch formations accelerate faster than earthflows in chaotic clay shales and reach higher velocities while the kinematic behaviour of the earthflows can be described as rather steady with only minor accelerations although we have no detailed pore pressure measurements for the period of interest the observed behaviour can be explained in our view by the morphological and hydrological characteristics of the different landslide types on the one hand landslide material and bedrock in the pelitic flysch rocks are more resistant which is why slope angles are higher in this lithology on the other hand landslides in the pelitic flysch formations have often deeper slip surfaces and landslide material is more permeable this is why long persistent rainfall is necessary to saturate the landslide material and induce pore pressures that are high enough to trigger displacement

el nino modoki and its possible teleconnection 1 using observed data sets mainly for the period 1979 2005 we find that anomalous warming events different from conventional el nino events occur in the central equatorial pacific this unique warming in the central equatorial pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly ssta on both sides along the equator empirical orthogonal function eof analysis of monthly tropical pacific ssta shows that these events are represented by the second mode that explains 12 of the variance since a majority of such events are not part of el nino evolution the phenomenon is named as el nino modoki pseudo el nino modoki is a classical japanese word which means a similar but different thing the el nino modoki involves ocean atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution analogous to the southern oscillation in the case of el nino hence the total entity is named as el nino southern oscillation enso modoki the enso modoki events significantly influence the temperature and precipitation over many parts of the globe depending on the season the impacts over regions such as the far east including japan new zealand western coast of united states etc are opposite to those of the conventional enso the difference maps between the two periods of 1979 2004 and 1958 1978 for various oceanic atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline this appears to be a cause of more frequent and persistent occurrence of the enso modoki event during recent decades

analysis and modeling of the combined effects of hydrological factors on a reservoir bank slope in the three gorges reservoir area china abstract more than 5000 landslides have been identified in the three gorges reservoir tgr area since the impoundment in 2003 which posed great threats to the residential houses transportation on the yangtze and dam stability this paper focuses on the evaluation of the coupled influence of rainfall and reservoir water on deformation characteristics and failure evolution of the outang landslide in china based on field investigations a statistical pearson cross correlation coefficient analysis multi technique monitoring data and a numerical model this instability is a reactivated ancient landslide with a volume of approximately 90 mm3 located in the three gorges reservoir the slope behavior is featured with a short period of fast displacement and a relatively long period of semi constant displacement rates per hydrological year and displacements velocities quicken gradually upslope rainfall and reservoir water level are the main triggering factors of slope movement existing in the upper and the lower parts of the landslide respectively based on the numerical results the failure evolution of this landslide is a compounded push retrogression type failure process involving a a first rupture at the toe caused by the reservoir water level that will rapidly mobilize a second and subsequent collapses upwards retrogression type and b the rock mass at the upper part will be pushed out and failed downslope push type due to precipitation these results provide a comprehensive analysis of the outang landslide which is critical for its management as well as for disaster prevention and mitigation of analogous reservoir induced landslides

slow moving landslides kinematic analysis and movement evolution modeling three of the most well known historical landslide areas in western greece were examined concerning their temporal and kinematic evolution long term ground displacements based on inclinometer data were analyzed the aim of this study is to estimate the velocity trend type of movement through the years the total time frame of kinematic evolution regarding the three currently studied landslide locations was over 20 years for panagopoula 1995 2017 10 years for karya 2005 2017 and 6 years for platanos 2011 2017 all three landslides occur in soil or soft rock of flysch and neogene formations in addition two statistical approaches time series decomposition and autoregressive integrated moving average arima method were applied to identify the specific kinematic features as well as model movement evolution in general these techniques are used to improve forecasts as to better understand the time series characteristics as a result the movement evolution over time is substituted into a model that explains the behavior of the displacements time series the models extracted from this analysis could overcome a common problem in long term monitoring regarding measurement missing data due to technical matters or non recorded periods

correlation of acoustic emissions with patterns of movement in an extremely slow moving landslide at peace river alberta canada the peace river region alberta canada has experienced extensive landslide activity since deglaciation shear zones within weak lacustrine silt and clay layers typically experience continuous cre

gis based landslide susceptibility assessment in seoul south korea applying the radius of influence to frequency ratio analysis the objective of this paper is to map landslide susceptibility using a statistical analysis model and the radius of influence within a geographic information systems environment the statistical analysis included triggering factors e g topography land cover forest and soil properties of adjacent areas in addition to the landslide sites themselves to estimate the probability of landslide occurrence using the radius of influence and to produce a landslide susceptibility index lsi we performed frequency radio fr analysis by applying the radius of influence to the domain of specific training sites landslide susceptibility maps were generated for each radius of influence ranging from 0 to 300 m in 30 m increments we observed enhanced fr index values corresponding to reduced exaggeration of statistical anomalies within the proper radius of influence it is referred that by adopting the radius of influence the classes that not only affect the landslide occurrence from the adjacent areas but also make anomaly errors can be taken into account in fr analysis moreover comparing the fr values between adopting the optimum radius of influence or not we inferred that the greater the gap the bigger influence of adjacent areas the classes have in the validation stage we identified the optimum radius of influence by measuring the area beneath the relative operating characteristics curve we found that the optimum radius of influence in the study area is 240 m for which the lsi map is 5 95 points more accurate than when not considering the radius of influence

experimental evidence for shallow slow moving landslides activated by a decrease in ground temperature in order to understand the trigger mechanism of slow moving landslides occurring in the early cold season from late autumn to winter we investigated the effect of temperature on the shear strength of slip surface soils displacement controlled and shear stress controlled box shear experiments were performed on undisturbed slip zone soils under residual strength conditions test results conducted at temperatures from 9 to 25 c showed remarkable shear strength reductions with decreasing temperature creep like slow shear displacements were induced by a decrease in temperature these temperature dependent shear behaviors are attributed to the rheological properties of hydrous smectite that dominantly compose the soil material along the failure surface our experimental results imply that ground temperature conditions influence slope instability especially for shallow landslides occurring in smectite bearing rock areas

landward migration of inner bars abstract a field investigation was carried out to collect data of inner bar migration profiles were measured once or twice a week for a two year period at naka beach ibaraki prefecture japan it was found that the onshore migration of inner bars could be described by two dimensionless quantities as 5d h b max h b max gt 2 max 20d h b max where h b max is the maximum value of daily average breaker height during one interval between surveys t max is the average wave period of the day giving h b max d is the mean size of the beach sediment and g is the acceleration due to gravity analyses based on surfzone sediment dynamics yields v wd b 2 10 11 h b d 3 where v is the average speed of onshore bar migration b is the bar height h b is the average breaker height and w is the fall velocity of the beach sediment nomographs for the speed of landward migrating bars are also presented

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

can tree tilting indicate mechanisms of slope movement abstract slope movements are a common natural hazard that is why considerable funds are spent annually to limit their effects or to research their prevention this study evaluates dendrometric approaches as a fast and low cost alternative to classical methods of slope movement mechanism analysis a total of 1688 trees growing on the mazak landslide in the moravskoslezske beskydy mts and 100 reference trees growing out of the landslide area were analysed the mazak landslide is approximately 400 m in length and presents varied morphological features scarps rotated blocks scree slopes shallow landslide areas etc the slope and direction of stem inclination was recorded for each tree the results were categorized into four distinct landforms scarp with outcrops of bedrock scree slope front of partial landslide block plateau of partial landslide block and were then compared with parameters for the reference trees the general model of tree tilting for the landslide area was verified and partially confirmed trees growing on the plateau of rotated blocks are predominantly oriented upslope trees growing on scree slopes of shallow movement and creep are predominantly oriented downslope trees growing on rocky scars do not differ significantly from the reference trees trees growing from fronts of rotated blocks are oriented both upslope and downslope from these results several recommendations regarding dendrometric evidence of slope movement mechanisms are presented i all trees growing on the landslide are to be analysed ii old trees maintain stem tilt intensities and directions for long periods but young trees are more sensitive to ground movements iii tree root depth influences root sensitivity to movements of various depths iv the general shape of a stem can denote specific mechanisms of slope movement and v comparisons with reference trees should always be conducted to exclude potential non geomorphic effects on tree stem tilt

remote sensing monitoring of a coastal valley earthflow in northwestern galicia spain abstract historical air photographs lidar and an unmanned aerial vehicle uav were used to record the movement from 1956 to 2018 of a clay and clast earthflow in a coastal valley in northwestern spain two procedures were employed the first tracked changes in a gis environment in the location of eight easily identified objects on the surface of the deposit large boulders topographic lobes and the foundations of an old hut the second used dems of difference dods based on digital elevation models from a 2011 lidar flight and two uav flights in 2016 and 2018 obtained by structure from motion photogrammetry techniques while the first procedure provided estimates for earthflow movement over a 62 year period the second produced more precise data for periods of up to 8 years the first procedure indicated that the mean rate of movement was 0 48 m yr 1 increasing from only 0 14 m yr 1 from 1956 to 1983 to between 0 50 and 0 83 m yr 1 from 1983 to 2018 despite some temporal and spatial changes in direction rates of surface movement were quite uniform on the deposit the increase in earthflow movement after 1983 may be related to an increase in rainfall although human activities associated with the removal of a wrecked ship from the nearshore may have been a contributing factor the role of debuttressing due to the wave induced removal of lateral support from the toe of the deposit is less clear while there was no clear relationship between wave erosion and rates of movement coastal retreat may have triggered changes in the direction and sediment flux in the toe of the deposit this effect could have been tempered by negative feedback however whereby coastal erosion and increased flow activity were countered by the protection afforded by the accumulation of large dislodged boulders on the beach because of this feedback it is difficult to predict the impact of sea level rise and other elements of climate change along this coast

some mudslide movement patterns a study has been made of the mechanisms of movement in a mudslide and the interrelationships between the controlling variables detailed monitoring has been conducted on a mudslide developed in the wealden beds a cretaceous mudrock the parameters which govern mudslide instability have been continuously monitored using electronic datalogging techniques slip can be divided into four components small multiple stick slip movements which are grouped temporally gradual or graded slip within defined temporal limits rapid surge events which occur over a short time interval and involve large displacements and unexplained random movements each of these four components occurs with varying frequency and at different times in the seasonal record slip is usually separated by periods of little or no change each component of mudslide movement displays characteristic patterns of pore water pressure change

failure forecast for large rock slides by surface displacement measurements forecasting the failure of large rock slides is difficult because of nonlinear time dependency and seasonal effects which affect the displacements starting from the accelerating creep theory prop

dendrogeomorphic chronologies of landslides dating of true slide movements dendrogeomorphic chronologies of landslide movements are frequently used to investigate past landslide activity slide areas are often affected by other slope movements e g creep simultaneously trees growing on landslides record all types of ground movements which potentially creates significant noise in tree ring based chronologies of landslide movements the effect of creep movements on dendrogeomorphic landslide chronologies was evaluated in a block type landslide in the south western foreland of the orlicke hory mts in total 272 trees p abies and f sylvatica were sampled 1088 increment cores on the sub horizontal surfaces of rotated slide blocks which were presumably created only by slide movements and on the steep internal scarps separating landslide blocks which were presumably created and affected by a combination of slide and creep movements ground movements were dated based on growth disturbances identified in an analysis of eccentric tree growth the trees growing on the internal landslide scarps separating the rotated blocks exhibited a significantly higher number and frequency of growth disturbances than those growing on the sub horizontal block surfaces all eight dated block surface movements were also identified on the internal scarps creep based events represented as many as 70 of the dated movement events on the internal scarps varying the it thresholds did not filter out more than 40 of the noise without significantly reducing the number of true dated slide events a significant difference was observed between the ability of p abies and f sylvatica to record ground movements by eccentric growth probably due its shallower roots and weaker anchoring of the tree to landslide blocks p abies appears to be more sensitive to surficial ground movement which potentially increases the proportion of dated creep events noise thus the careful selection of sampled tree species with different physiologies should be considered during dendrogeomorphic field sampling

transient reactivation of a deep seated landslide by undrained loading captured with repeat airborne and terrestrial lidar landslides reactivate due to external environmental forcing or internal mass redistribution but the process is rarely documented quantitatively we capture the three dimensional 1 m resolution surface deformation field of a transiently reactivated landslide with image correlation of repeat airborne lidar undrained loading by two debris flows in the landslide s head rather than external forcing triggered reactivation after that loading the lower 2 km of the landslide advanced by up to 14 m in 2 years before completely stopping the displacement field over those 2 years implies that the slip surface gained 1 kpa of shear strength which was likely accomplished by a negative dilatancy pore pressure feedback as material deformed around basal roughness elements thus landslide motion can be decoupled from external environmental forcing in cases motivating the need to better understand internal perturbations to the stress field to predict hazards and sediment fluxes as landscapes evolve