styles of failure in late holocene highstand prodelta wedges on the adriatic shelf on the continental shelves of the northern mediterranean basin the late holocene highstand systems tract hst prograded un der the influence of major rivers after the attainment of the present sea level highstand about 5 5 cal kyr bp on the adriatic shelf the thickness distribution of the late holocene hst reflects the location of major deltas on the western side of the basin and the geostrophic cir culation which prevents a more uniform sediment dispersal toward the center of the basin very high sediment accumulation rates 1 to 10 cm year resulted in the construction of a hst depocenter up to 35 m thick this shore parallel depocenter is affected by failure of limited displacement over as much as 40 of its extent gas impregnation is common in the topset region and occurs at very shallow levels a few meters below the sea floor five areas are characterized by a variety of sea floor and subsurface crenulations although locally some of these crenulations have an intriguingly regular geometry sediment failure is the most plausible mechanism for their formation sediment failure better explains the large variety of geometries that characterizes the coastal mud prism of the late holocene hst furthermore we observe that these crenulations occur only where the downlap surface at the base of the hst is disrupted and affected by geometries that are con sistent with fluid escape processes this relationship suggests that the basal surface acts as a weak layer for sediment failure failure occurred in variable water depths from the northern slope of the modern po prodelta 10 20 m water depth to the narrow shelf offshore bari 40 110 m water depth in all these areas the proximal part of the hst prodelta wedge is intensely gas charged the thickness and age of the sediment sections affected by failure are slightly differ ent from place to place but appear everywhere younger than 5 5 cal kyr bp where failure affects the entire hst the detachment occurs on the downlap surface at its base failure geometries characterize the head region whereas compressional features such as pressure ridges and mud diapirs dominate in the toe region ranging in depth between 70 and 110 m where failure is limited to the upper few meters of the hst there is a clear lithologic change decrease in carbonate fraction and grain size across the basal surface this lithological change reflects a switch in sediment supply from local apennine rivers below to po derived mud this change occurred at the onset of the little ice age documenting the indirect control of short term climate change and hu man impact on sediment architecture the deformations affecting the late holocene hst in the various areas show differences in internal geometry but appear everywhere to be characterized by limited downward displacement and can be attri buted to shear dominated retrogressive failure it is suggested that some degree of consolidation occurred immediately after mobilization possibly induced by the escape of fluids nowhere has failure evolved into disintegration and flow likely because the type of cyclic loading that triggered it was not prolonged over a long enough interval short lived radionuclides in the uppermost stratigraphic layers which postdate the failure in the area offshore ortona allowed us to quantify systematic changes in sediment accumulation rates as a func tion of the underlying deformed sea floor in areas of wavy sea floor troughs show sediment accumulation rates of greater than 16 mm yr a figure that is fourfold the rate measured on the flanks of the troughs

a high resolution record of the last deglaciation in the southern tyrrhenian sea environmental and climatic evolution a multidisciplinary study was carried out on core c106 collected in the salerno gulf southern tyrrhenian sea two tephra layers recovered in the core n 18 o record of globigerinoides ruber and globigerina bulloides and seven 14 c calibrated ages provided the stratigraphic framework the core sediments cover the last 28 kyr bp seismostratigraphic analysis of a high resolution acoustic profile integrated by the dated core samples allowed us to reconstruct the architecture and age of sedimentary bodies on the continental shelf an integrated study based on different taxonomic groups nannofossils pteropods foraminifera and palynomorphs provided palaeoclimatic trends in agreement with changes in the isotopic composition of oxygen the upper part of the last glacial period the deglaciation phase and the holocene were identified correlation between marine and continental records of palaeoenvironmental changes confirms a similar reconstruction of the last deglaciation as in the central and southern mediterranean sea the late pleistocene holocene boundary was recognised at about 11 7 kyr bp between about 9 5 and 6 kyr bpand at 3 3 kyr bpsome warmer episodes were recorded the measured lower isotopic values together with some features of the fossil assemblages recorded from 9 5 to 6 kyr bp may be related to the oceanographic setting that led to the deposition of sapropel s1 in the mediterranean basin 2002 elsevier science b v all rights reserved

detransformation of the british geomagnetic secular variation record for holocene times in this note we replot the british post glacial secular variation curve in terms of actual values of declination and inclination rather than the transformed declination and inclination system used in our original paper turner thompson 1981 this should facilitate the comparison of our record with contemporaneous european archaeomagnetic data our composite record was obtained by averaging the dated records from 10 cores of lake sediment the sequence of unit vectors describing the magnetic direction record of each core was rotated so as to place its mean direction the mean over the section of core dated between 0 and 7000 bp the time span of the shortest core at zero transformed declination and inclination dt o it 0 the transformed coordinate frame of each core is thus derived from its mean direction assumed to represent the mean geomagnetic field direction over the 7000 yr period rather than from the core tube and its orientation during coring hence the problem of not knowing the azimuthal orientation and inclination of the corer during core collection is avoided and the 10 records can be averaged in this coordinate system transformed coordinates then provide a convenient generalised method of plotting averaged sediment records however in the archaeomagnetic method sample orientation is straightforward and the results can readily be plotted as absolute declination and inclination values so for consistency when comparing the two we have attempted here to detransform our record the following procedures assumptions and approximations were taken to produce the detransformed magnetograms and bauer type plots of figs 1 and 2 1 amplitude correction although the combination of 10 data sets produces a good estimate of the signature of the geomagnetic variations the following factors contribute to an overall loss of amplitude in both declination and inclination a the quality of magnetic recording varies widely between different sediments depending on the porosity of the sediment the size and shape distributions and the nature of the magnetic carrier verosub 1979 the loch lomond sediments carry a good high amplitude pattern of remanent directions of which the most recent closely follow the london observatory records the much wetter and less compacted sediments of llyn geirionydd on the

the summer circulation in the gulf of suez and its influence in the red sea thermohaline circulation abstractthe gulf of suez is accepted as an important location for red sea deep water formation but the circulation and exchange with the red sea around the year remains elusive a summer cruise in the area gives the opportunity to investigate features of the summertime hydrological structure and exchange with the red sea an inverse estuarine circulation and exchange with the red sea is evident the topographic patterns of the gulf play an important role in the circulation two sills one in midbasin and a second at the mouth of the gulf inhibit the bottom flow topographically trapping waters that were formed in the cold season although the water mass characteristics of the outflowing waters during the other seasons are not directly related to the deep waters they can influence the water column structure of the northern red sea a simple box model shows that their contribution can have a significant influence in the formation of the intermediate layer a hypersaline 40 6 psu but relatively warm 23

holocene history of deep seated landsliding in the north fork stillaguamish river valley from surface roughness analysis radiocarbon dating and numerical landscape evolution modeling documenting spatial and temporal patterns of past landsliding is a challenging step in quantifying the effect of landslides on landscape evolution while landslide inventories can map spatial distributions lack of dateable material landslide reactivations or time access and cost constraints generally limit dating large numbers of landslides to analyze temporal patterns here we quantify the record of the holocene history of deep seated landsliding along a 25 km stretch of the north fork stillaguamish river valley washington state usa including the 2014 oso landslide which killed 43 people we estimate the ages of more than 200 deep seated landslides in glacial sediment by defining an empirical relationship between landslide deposit age from radiocarbon dating and landslide deposit surface roughness we show that roughness systematically decreases with age as a function of topographic wavelength consistent with models of disturbance driven soil transport the age roughness model predicts a peak in landslide frequency 1 000 ybp with very few landslide deposits older than 7 000 ybp or younger than 100 ybp likely reflecting a combination of preservation bias and a complex history of changing climate base level and seismic shaking in the study area most recent landslides have occurred where channels actively interact with the toes of hillslopes composed of glacial sediments suggesting that lateral channel migration is a primary control on the location of large deep seated landslides in the valley

a source to sink perspective of the waipaoa river margin abstract a fundamental goal of the earth science community is to understand how perturbations on earth s surface are preserved in the stratigraphic record recent source to sink s2s studies of the waipaoa sedimentary system wss new zealand are synthesized herein to provide a holistic perspective of the processes that generate transport and preserve sedimentary strata and organic carbon on the waipaoa margin in the late quaternary rapid uplift associated with subduction processes and weak sedimentary units have conspired to generate rapid rates of incision and erosion in the waipaoa catchment since the last glacial maximum lgm we show that although much of the sediment exported offshore during this time interval originated from valley excavation a substantial portion emanated from hillslopes mostly through deep seated landslide and earthflow processes that were vigorous during periods of rapid fluvial incision just prior to the pleistocene holocene transition lacustrine sediments deposited in naturally dammed 7 ky old lake tutira provide a record of holocene environmental controls on upper catchment sedimentation in the wss with 1400 storms identified storm frequency is modulated by the waxing and waning of atmospheric teleconnections between the tropics and antarctica furthermore clear long term changes in sediment yield are evident from the lake tutira record following human settlement as conversion to pasture is accompanied by a 3 fold increase in the long term lake sediment accumulation rate whereas there is ample evidence that waipaoa river flood deposits are routinely deposited offshore in the sheltered confines of poverty bay over the longer term waves and currents subsequently resuspend and transport these deposits both landward sandy fraction and seaward finer fraction thus the timing of sediment supply to areas of net sediment accumulation is more often driven by wave events that are not associated with river flooding therefore we conclude that asynchronicity of river sediment delivery and of wave resuspension in most instances precludes the direct preservation of flood events in the stratigraphic record of the waipaoa shelf over the longer term the sediment package preserved on the shelf and slope since the lgm can be explained in large measure by sequence stratigraphic models forced by varying sea level and ongoing tectonic deformation of the margin as sea level rose sediment supply to the slope was reduced by about a factor of 5 due to shelf trapping despite this reduction turbidites are found at similar frequency throughout the lgm present as the dominant trigger appears to be subduction earthquakes with large ones having a return interval of about 200 100 years sediment budget exercises that consider both modern river discharge versus centennial accumulation rates and post lgm terrestrial production versus offshore isopachs mass balances indicate that about half of the total sediment production from the waipaoa escapes the study area moreover a coupled sediment transport hydrodynamic model and observations of textural trends on the shelf indicate that a large fraction of the sediment is carried outside the study area along the shelf to the northeast by the river plume or by combined current wave activity therefore we conclude that the wss is an open system with sediment escape from the present day through the lgm the organic matter associated with sediment as it moves from upland source to marine sink is a product of particle history and provides a record of materials that have cycled over timescales of days to millions of years the ubiquity of fossil organic carbon oc in both the terrestrial and marine realms of the waipaoa attests both to the chronic nature of its source crumbling mudstones further destabilized by land use and its biogeochemical recalcitrance modern oc persists by virtue of its continual production along the s2s transit and is buried and preserved within the adjacent marine depocenters the waipaoa contrasts with dispersal systems on wide energetic shelves e g the amazon and fly rivers where sediment is extensively refluxed in oxygenated overlying water resulting in the biogeochemical incineration of particulate oc the waipaoa like other small mountainous rivers on active margins exhibits a high riverine oc preservation efficiency 50 in its marine depocenters because of the relatively rapid event driven accumulation of sediment

new advances for paleomagnetic studies of sediment cores using u channels accurate and detailed paleomagnetic data can be obtained from continuous measurements of u channels extracted from sedimentary cores using a small diameter pass through magnetometer and high resolution signal response pick up coils the spatial resolution is not significantly lower than that obtained by measuring standard paleomagnetic samples and features on the order of 3 5 cm can be confidently resolved we propose a method to analyze the demagnetization data based on the angular dispersion of the directions between successive demagnetization steps and the downcore changes in the rate of intensity decrease this technique allows us to distinguish very rapidly between intervals with well identified characteristic magnetic components and zones characterized by a more complex behavior during demagnetization it is also possible to directly measure the magnetic susceptibility and to induce and measure most rock magnetic properties along the u channels thus all parameters necessary for a complete paleomagnetic study of sediment cores can be confidently obtained directly from u channels without extracting individual samples finally this equipment makes possible the measurement and complete demagnetization of up to 10 single samples at a time in less than one hour by using techniques similar to those developed for the u channels

a cosmic trip 25 years of cosmogenic nuclides in geology terrestrial cosmogenic nuclides produced by secondary cosmic ray interactions in the atmosphere and in situ within minerals in the shallow lithosphere are widely used to date surface exposure of rocks and sediments to estimate erosion and weathering rates and to date sediment deposition or burial their use has transformed geomorphology and quaternary geology for the first time allowing landforms to be dated and denudation rates to be measured over soil forming time scales the application of cosmogenic nuclides to geology began soon after the invention of accelerator mass spectrometry ams in 1977 and increased dramatically with the measurement of in situ produced nuclides in mineral grains near earth s surface in the 1980s the past 25 yr have witnessed the development of cosmogenic nuclides from their initial detection to their prevalence today as a standard geochronological and geochemical tool this review covers the major developments of the past 25 yr by comparing the state of the field in 1988 with that of today and by identifying key advances in that period that moved the field forward we emphasize the most commonly used in situ produced nuclides measured by ams for geological applications but we also discuss other nuclides where their applications overlap our review covers ams instrumentation cosmogenic nuclide production rates the methods of surface exposure dating measurement of erosion and weathering and burial dating and meteoric 10 be in memoriam devendra lal 1929 2012 whose vision inspired the field

using dinsar airborne lidar and archival air photos to quantify landsliding and sediment transport 1 we demonstrate the ability of coupled remote sensing tools to characterize large slow moving landslides in the eel river catchment northern california from a stack of alos interferograms we identified 5 large 1 km long landslides that exhibited significant activity from february 2007 to february 2008 for the boulder creek earthflow we used orthorectified air photos taken in 1964 and unfiltered airborne lidar flown in 2006 to map the displacement of trees growing on the landslide surface combining those displacement orientations with stacked dinsar data we observed average downslope velocities of 0 65 m yr 1 through the central transport zone of the landslide given landslide depth estimates minimum sediment transport and denudation rates are estimated to be 4100 m3 yr 1 and 1 6 mm yr 1 respectively our results demonstrate the highly erosive role of large slow moving landslides in landscape evolution and suggest that the superposition of dense ephemeral gully networks and rapidly moving zones within the landslide may facilitate delivery of slide mobilized sediment into adjacent fluvial channels

high resolution petrophysical and palaeomagnetic study of late holocene shelf sediments salerno gulf tyrrhenian sea records of geomagnetic secular variation have been obtained from three cores recovered from the salerno gulf southern italy high resolution petrophysical and palaeomagnetic measurements enabled the reconstruction of a composite curve of geomagnetic palaeosecular variation psv which is compared with the reconstructed psv curve from britain and with the french archaeomagnetic data of the last 2 1ka the good agreement of the salerno gulf record with the above data conforms that our psv record reaches back for some 9 0ka in addition to a thick pumice layer originated during the somma vesuvius eruption at 79 two other tephra layers were recognized at about 1 3 and 3 0ka bp that are probably also of vesuvian origin the comparison provides an initial chronological framework for assessing the increasing trend of sedimentation rate and its significant changes at about 2 7ka and 7 0ka bp this variation in the deposition rate suggests a link with climatic changes recognized in the mediterranean region

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

sea level change along the french mediterranean coast for the past 30 000 years abstract observational evidence for sea level change along the french mediterranean coast has been examined and compared with glacio hydro isostatic models to predict the spatial and temporal patterns of change for about the past 30 000 14c years these predictions are pertinent to discussions of changing ocean volumes during this interval the tectonic stability or otherwise of the coastal areas mantle rheology and the timing of possible human occupation of the now submerged coastal plain and caves such as cosquer cave near marseille the principal results from the analysis are i sea levels along this section of the coast have risen continually since the time of the last glacial maximum lgm and at no time during the holocene has the mean sea level been higher than that of today ii the coast has been tectonically stable between marseille and nice as well as further to the west in roussillon western corsica may have experienced a slow tectonic uplift of between 0 15 0 3 mm year for the past 3000 years but northernmost corsica appears to have been stable during this same interval iii during the lgm sea levels along the coast and immediate off shore areas stood at between 105 115 m below present level the range reflecting the importance of the isostatic contributions during oxygen isotope stage 3 sea levels do not appear to have risen locally above about 60 m iv the rebound parameters describing the mantle rheology and ice sheets required to match the limited observational evidence are consistent with the results of similar analyses carried out for other parts of europe because of its distance from the former northern ice sheets the isostatic factors are particularly sensitive to the value of the lower mantle viscosity v the model predictions for sea level change at the cosquer cave site and for its immediate environments indicate that the cave was last readily accessible before about 10 700 500 14c years about 12 500 500 cal years bp and that the cave entrance was completely flooded by 9000 200 radiocarbon years bp between about 9800 and 10 300 calibrated years bp the cave was above sea level throughout the oxygen isotope stage 3

10be distribution in soils from merced river terraces california abstract the distribution and residence time of cosmogenic 10 be in clay rich soil horizons is fundamental to understanding and modelling the migration of 10 be on terrestrial sediments and in groundwater solutions we have analyzed seven profiles of clay rich soils developed from terrace sediments of the merced river california the terraces and soils of increasing age are used to compare the 10 be inventory with a simple model of accumulation decay and erosion the data show that the distribution of 10 be varies with soil horizon clay content that the residence time of 10 be in these horizons exceeds 10 5 years and that to a rough approximation the inventory of 10 be in a thoroughly sampled soil profile fits the equation n q em 1 e where q is delivery rate e is erosion rate m is the concentration of 10 be in the eroding surface layer is the decay constant and t is the age of the depositional unit from which the soil has developed the general applicability of this model is uncertain and warrants further testing in well calibrated terrace sequences

quantification of soil production and downslope creep rates from cosmogenic 10be accumulations on a hillslope profile average soil transport rates over a period of 3500 yr on a convex soil mantled hillslope have been quantified using a mass balance model that incorporates the soil concentration of the cosmogenic isotope 10 be the 10 be model results support the assumption used in most geomorphic models that the soil creep rate is proportional to surface gradient the predicted diffusion coefficient is 360 55 cm 3 yr 1 cm 1 contour length and the average rate of soil production is 0 026 0 007 cm yr within the uncertainty of this technique the data do not reject g k gilbert9s hypothesis that some hillslopes may exist in a condition of dynamic equilibrium with a uniform soil production rate however the model does not require an assumption of dynamic equilibrium and may be an approach that uniquely allows the quantification of a local soil production rate law

the holocene paleosecular variation record from elk lake minnesota the paleosecular variation record of the geomagnetic field from elk lake minnesota is presented and its implications are discussed the elk lake record is compiled from measurements of four parallel cores with a 2 cm sampling interval 15 years time control is provided by radiocarbon dates and by annual laminations varves in the sediment stratigraphic control is provided by the annual laminations and by fine scale 2 5 cm variations in magnetic susceptibility the varve chronology provides improved time control for the central north american paleosecular variation record back to about 4000 years the results of this study largely confirm the results of lund and banerjee from lake st croix and kylen lake and demonstrate the general utility of holocene sediment paleomagnetic records differences between the records appear to be due to experimental procedure so minimal procedures are recommended for future work comparison of north american and european records suggests that two drifting non dipole sources one having its advent during the last 5000 years can account for much of the secular variation

landslide kinematics and their potential controls from hourly to decadal timescales insights from integrating ground based insar measurements with structural maps and long term monitoring data abstract knowledge of kinematics is rudimentary for understanding landslide controls and is increasingly valuable with greater spatiotemporal coverage however characterizing landslide wide kinematics is rare especially at broadly ranging timescales we used highly detailed kinematic data obtained using photogrammetry and field mapping during the 1980s and 1990s and our 4 3 day ground based insar survey during 2010 to study kinematics of the large persistently moving slumgullion landslide the landslide was segregated into 11 kinematic elements using the 1980s 1990s data and the insar survey revealed most of these elements within a few hours averages of insar derived displacement point measures within each element agreed well with higher quality in situ observations averaging was deemed necessary because adverse look angles for the radar coupled with tree cover on the landslide introduced error in the insar results we found that the landslide moved during 2010 at about half its 1985 1990 speed but slowing was most pronounced at the landslide head gradually decreased precipitation and increased temperature between the periods likely resulted in lower groundwater levels and consequent slowing of the landslide we used gps survey results and limit equilibrium modeling to analyze changing stability of the landslide head from observed thinning and found that its stability increased between the two periods which would result in its slowing and the consequent slowing of the entire landslide additionally insar results suggested movement of kinematic element boundaries in the head region and our field mapping verified that they moved and changed character likely because of the long term increasing head stability on an hourly basis insar results were near error bounds but suggested landslide acceleration in response to seemingly negligible rainfall pore pressure diffusion modeling suggested that rainfall infiltration affected frictional strength only to shallow depths along the landslide s marginal faults highlighting their importance in controlling landslide stability hourly results also suggested that motion propagated along the 3 9 km length of the active landslide even following sub millimeter displacements while strengthening of landslide shear boundaries during faster movement was likely critical in regulating the landslide s motion hence detailed kinematic characterizations obtained from traditional and emerging approaches helped to reveal that mechanisms controlling landslide movement and evolution over decades also are critical to sub millimeter movement on a nearly continuous basis

a comparison of different magnetic methods for determining the relative grain size of magnetite in natural materials some results from lake sediments abstract a new rapid method for identifying relative grain size variations in magnetic involves the parameter anhysteretic susceptibility arm i e specific arm obtained in a 1 oe steady field which is particularly sensitive to the single domain sd and small pseudo single domain psd grains of the finer magnetite fraction a second parameter low field susceptibility is relatively more sensitive to the coarser magnetite fraction larger psd and smaller multidomain md grains we can then obtain a measure of the ratio of coarse to fine grain magnetite for large numbers of samples by plotting arversus a simple idealized model based on sized magnetite samples is proposed to explain the use of the armversus plot for detecting relative grain size changes in the magnetic content of natural materials the sediments of three lakes that contain magnetite or a similar magnetic carrier and have a wide range of values of arm and are used to test the model the model is used to interpret the magnetic variations observed and the interpretations are supported by high field hysteresis measurements of the same sediments the combination of the high field hysteresis method of day et al 1 and the arm vs method is a powerful technique allowing the rapid identification of both the relative grain size and domain state for large numbers of samples containing magnetite the armvs method should be used as an intial means of identifying distinct groups of samples the high field hysteresis method should then be applied to a few representative samples from each group to confirm the initial interpretation

palaeomagnetism of holocene and late pleistocene sediments from lago di mezzano and lago grande di monticchio italy initial results abstract palaeomagnetic records of the geomagnetic secular variation reaching back to 31 and 102 kyr cal bp respectively were obtained from two sediment cores from lago di mezzano central italy and two cores from lago grande di monticchio southern italy intra lake correlation was based on continuous high resolution susceptibility measurements and discrete dry density samples characteristic remanent magnetization chrm of all 4800 samples was determined by analysis of the results of progressive alternating field af demagnetization intra lake comparison of the resulting chrm directions confirms that the inclination and declination records reflect the palaeosecular variation of the local geomagnetic field composite curves of geomagnetic palaeosecular variations psv were created for each lake in order to compare the reconstructed psv records with those from lac du bouchet massif central france and lac de joux switzerland the good agreement in the general patterns of the inclination and declination records of all lakes mentioned above confirms the reconstructed psv records of the italian lakes investigated

unsteady sediment discharge in earth flows a case study from the mount pizzuto earth flow southern italy abstract surface mapping gps surveys t lidar surveys boreholes seismic profiles and hvsr measurements were used to study the mechanisms of sediment transport along the mount pizzuto earth flow in southern italy the earth flow has several kinematic zones with transitional areas marked by changing structural styles from compressional structures thrusts upslope to extensional structures normal faults downslope we relate sediment discharge at these transitional zones to internal strain the results suggest that during surge events flow acceleration starts within the head and propagates downslope inducing a cascade effect between kinematic zones during surge events the average sediment discharge is nearly constant and a change from sliding to flowing allows propagation of movement towards the toe during slow movement kinematic zones are independent and sediment discharge varies along the flow in general the velocity profile and the structural style are controlled by the basal slip surface the implications are i sediment discharge is not constant but is a function of the earth flow activity ii during surge earth flow material behaves similar to an incompressible fluid and iii the distribution of surface structures can provide information about the geometry of the slip surface and the velocity profile additionally earth flows with a well defined neck seem to be more likely to surge with respect to those without

meteoric 10be in soil profiles a global meta analysis abstract in order to assess current understanding of meteoric 10 be dynamics and distribution in terrestrial soils we assembled a database of all published meteoric 10 be soil depth profiles including 104 profiles from 27 studies in globally diverse locations collectively containing 679 individual measurements this allows for the systematic comparison of meteoric 10 be concentration to other soil characteristics and the comparison of profile depth distributions between geologic settings percent clay 9 be and dithionite citrate extracted al positively correlate to meteoric 10 be in more than half of the soils where they were measured but the lack of significant correlation in other soils suggests that no one soil factor controls meteoric 10 be distribution with depth dithionite citrate extracted fe and cation exchange capacity are only weakly correlated to meteoric 10 be percent organic carbon and ph are not significantly related to meteoric 10 be concentration when all data are complied the compilation shows that meteoric 10 be concentration is seldom uniform with depth in a soil profile in young or rapidly eroding soils maximum meteoric 10 be concentrations are typically found in the uppermost 20 cm in older more slowly eroding soils the highest meteoric 10 be concentrations are found at depth usually between 50 and 200 cm we find that the highest measured meteoric 10 be concentration in a soil profile is an important metric as both the value and the depth of the maximum meteoric 10 be concentration correlate with the total measured meteoric 10 be inventory of the soil profile in order to refine the use of meteoric 10 be as an estimator of soil erosion rate we compare near surface meteoric 10 be concentrations to total meteoric 10 be soil inventories these trends are used to calibrate models of meteoric 10 be loss by soil erosion erosion rates calculated using this method vary based on the assumed depth and timing of erosional events and on the reference data selected

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

a 1 d mechanistic model for the evolution of earthflow prone hillslopes 1 in mountainous terrain deep seated landslides transport large volumes of material on hillslopes exerting a dominant control on erosion rates and landscape form here we develop a mathematical landscape evolution model to explore interactions between deep seated earthflows soil creep and gully processes at the drainage basin scale over geomorphically relevant 10 3 year timescales in the model sediment flux or incision laws for these three geomorphic processes combine to determine the morphology of actively uplifting and eroding steady state topographic profiles we apply the model to three sites one in the gabilan mesa california with no earthflow activity and two along the eel river california with different lithologies and varying levels of historic earthflow activity representative topographic profiles from these sites are consistent with model predictions in which the magnitude of a dimensionless earthflow number based on a non newtonian flow rheology reflects the magnitude of recent earthflow activity on the different hillslopes the model accurately predicts the behavior of earthflow collection and transport zones observed in the field and estimates long term average sediment fluxes that are due to earthflows in agreement with historical rates at our field sites finally our model predicts that steady state hillslope relief in earthflow prone terrain increases nonlinearly with the tectonic uplift rate suggesting that the mean hillslope angle may record uplift rate in earthflow prone landscapes even at high uplift rates where threshold slope processes normally limit further topographic development

historic drought puts the brakes on earthflows in northern california california s ongoing unprecedented drought is having profound impacts on the state s resources here we assess its impact on 98 deep seated slow moving landslides in northern california we used aerial photograph analysis satellite interferometry and satellite pixel tracking to measure earthflow velocities spanning 1944 2015 and compared these trends with the palmer drought severity index a proxy for soil moisture and pore pressure that governs landslide motion we find that earthflow velocities reached a historical low in the 2012 2015 drought but that their deceleration began at the turn of the century in response to a longer term moisture deficit our analysis implies depth dependent sensitivity of earthflows to climate forcing with thicker earthflows reflecting longer term climate trends and thinner earthflows exhibiting less systematic velocity variations these findings have implications for mechanical hydrologic interactions that link landslide movement with climate change as well as sediment delivery in the region

a high resolution late holocene palaeo environmental record from the central adriatic sea a multi proxy study of a holocene sediment core rf 93 30 from the western flank of the central adriatic in 77 m of water reveals a sequence of changes in terrestrial vegetation terrigenous sediment input and benthic fauna as well as evidence for variations in sea surface temperature spanning most of the last 7000 yr the chronology of sedimentation is based on several lines of evidence including ams 14c dates of foraminifera extracted from the core palaeomagnetic secular variation pollen indicators and dated tephra the temporal resolution increases towards the surface and for some of the properties measured is sub decadal for the last few centuries the main changes recorded in vegetation sedimentation and benthic foraminiferal assemblages appear to be directly related to human activity in the sediment source area which includes the po valley and the eastern flanks of the central and northern appenines the most striking episodes of deforestation and expanding human impact begin around 3600 bp late bronze age and 700 bp medieval and each leads to an acceleration in mass sedimentation and an increase in the proportion of terrigenous material reflecting the response of surface processes to widespread forest clearance and cultivation although human impact appears to be the proximal cause of these changes climatic effects may also have been important during these periods signs of stress are detectable in the benthic foram morphotype assemblages between these two periods of increased terrigeneous sedimentation there is smaller peak in sedimentation rate around 2400bp which is not associated with evidence for deforestation shifts in the balance between terrigenous and authigenic sedimentation or changes in benthic foraminifera the mineral magnetic record provides a sensitive indicator of changing sediment sources during forested periods of reduced terrigenous input it is dominated by authigenic bacterial magnetite whereas during periods of increased erosion anti ferromagetic minerals haematite and or goethite become more important as well as both paramagnetic minerals and super paramagnetic magnetite analysis of the alkenone u37k record provides an indication of possible changes in sea surface temperature during the period but it is premature to place too much reliance on these inferred changes until the indirect effects of past changes in the depth of the halocline and in circulation have been more fully evaluated the combination of methods used and the results obtained illustrate the potential value of such high resolution near shore marine sedimentary sequences for recording wide scale human impact documenting the effects of this on marine sedimentation and fauna and potentially disentangling evidence for human activities from that for past changes in climate

simulating the mobility of meteoric 10be in the landscape through a coupled soil hillslope model be2d meteoric 10be allows for the quantification of vertical and lateral soil fluxes over long time scales 103 105yr however the mobility of meteoric 10be in the soil system makes a translation of meteoric 10be inventories into erosion and deposition rates complex here we present a spatially explicit 2d model simulating the behaviour of meteoric 10be on a hillslope the model consists of two parts the first component deals with advective and diffusive mobility of meteoric 10be within the soil profile and the second component describes lateral soil and meteoric 10be fluxes over the hillslope soil depth is calculated dynamically accounting for soil production through weathering as well as downslope fluxes of soil due to creep water and tillage erosion synthetic model simulations show that meteoric 10be inventories can be related to erosion and deposition across a wide range of geomorphological and pedological settings our results also show that meteoric 10be can be used as a tracer to detect human impact on soil fluxes for soils with a high affinity for meteoric 10be however the quantification of vertical mobility is essential for a correct interpretation of the observed variations in meteoric 10be profiles and inventories application of the be2d model to natural conditions using data sets from the southern piedmont bacon et al 2012 and appalachian mountains jungers et al 2009 west et al 2013 allows to reliably constrain parameter values good agreement between simulated and observed meteoric 10be concentrations and inventories is obtained with realistic parameter values furthermore our results provide detailed insights into the processes redistributing meteoric 10be at the soil hillslope scale

topographic signatures and a general transport law for deep seated landslides in a landscape evolution model a fundamental goal of studying earth surface processes is to disentangle the complex web of interactions among baselevel tectonics climate and rock properties that generate characteristic landforms mechanistic geomorphic transport laws can quantitatively address this goal but no widely accepted law for landslides exists here we propose a transport law for deep seated landslides in weathered bedrock and demonstrate its utility using a two dimensional numerical landscape evolution model informed by study areas in the waipaoa catchment new zealand and the eel river catchment california we define a non dimensional landslide number which is the ratio of the horizontal landslide flux to the vertical tectonic flux that characterizes three distinct landscape types one is dominated by stochastic landsliding whereby discrete landslide events episodically erode material at rates exceeding the long term uplift rate another is characterized by steady landsliding in which the landslide flux at any location remains constant through time and is greatest at the steepest locations in the catchment the third is not significantly affected by landsliding in both the stochastic landsliding and steady landsliding regimes increases in the non dimensional landslide number systematically reduce catchment relief and widen valley spacing producing long low angle hillslopes despite high uplift rates the stochastic landsliding regime captures the frequent observation that deep seated landslides produce large sediment fluxes from small areal extents while being active only a fraction of the time we suggest that this model is adaptable to a wide range of geologic settings and is useful for interpreting climate driven changes in landslide behavior

structural and sedimentary features in the tyrrhenian margin off campania southern italy abstract the utilization of multichannel seismic reflection profiles permits the identification of the generally e w trending miocene orogenic and plio quaternary post orogenic features of apennine nw se and anti apennine ne sw trends in the campanian margin the former features are constituted by carbonate and or allochthonous sheets which were thrust mainly towards the north and northeast during the miocene tectogenetic phases the latter are represented by extensional structures which affected the orogenic features during plio quaternary times the anti apennine tectonic trend is responsible for the recent late pliocene quaternary and remarkable block faulting differential subsidence of the southern margin as well as for its present morphology the ragged and disconnected pattern of the allochthonous units over the present day slope and their accumulation underneath the shelf area suggest that they are the result of gravitational gliding tectonics gravity cores and 3 5 khz subbottom profiles indicate that the salerno trough and capri basin areas are characterized by a particular neotectonic mobility this is proved by the thick and coarse grained sediment accumulation from steep relief produced by block faulting this faulting created uplift belts serving as sediment source

surface movement in an earthflow complex raukumara peninsula new zealand abstract the surface movement of an unstable earthflow complex was studied over a 10 year period using a network of pegs inserted to a depth of 1 m the mean and maximum surface movement velocities in the transport zones of the two study earthflows ranged from 0 2 0 4 m and 1 7 2 8 m month respectively maximum velocities for individual pegs ranged up to 3 m month the movement data indicated that the earthflows were approximately in a steady state for the 10 year duration of the study application of iverson s theory for the kinematics of unsteady non uniform landslide movement indicated that the earthflows had pe values in the range of 0 1 to 2 0 pe is the dimensionless parameter known as the landslide peclet number these values indicated that the earthflows showeda blend of plastic and viscous behaviour and that diffusion might be more significant than kinematic wave propagation in transmitting disturbances

long term kinematics and sediment flux of an active earthflow eel river california although earthfl ows are the dominant erosion mechanism in many mountainous landscapes estimates of long term earthfl ow driven sediment fl ux remain elusive because landslide displacement data are typically limited to contemporary time periods combining high resolution topography from airborne lidar light detection and ranging total station surveying orthorectifi ed historical aerial photographs and inventories of meteoric 10 be in soil pits we quantifi ed 150 years of slope movement on a 1 5 km long earthfl ow in the eel river catchment northern california united states using lidar derived topography we mapped the upper half of the earthfl ow into three distinct kinematic zones an upslope source area a long narrow transport zone and a mid slope compressional zone from our air photo analysis 1944 2006 average velocities are fastest in the transport zone 1 7 m a slowest in the source zone 1 m a and decrease monotonically over the past 30 years in all three zones meteoric 10 be inventories systematically increase with distance downslope of the source area consistent with the notion that the elongate transport zone acts like a relatively undeformed soil conveyor that can be used to quantify long term displacement because our 10 be derived transport zone velocity of 2 1 m a averages over the past 150 years pre 1944 velocities likely approached 2 5 m a suggesting that twentieth century land use practices have not increased rates of sliding although our results reveal a progressive decline in velocity that may refl ect exhaustion of readily mobilized source material velocities temporarily increased in the midtwentieth century due to major hydrologic events given an average velocity of 2 m a the kekawaka earthfl ow is defl ating its source area over 20 times faster than the regional erosion rate emphasizing the localized and vigorous role of active earthfl ows in landscape evolution

sediment yield spatial characteristics and the long term evolution of active earthflows determined from airborne lidar and historical aerial photographs eel river california in mountainous landscapes with weak fine grained rocks earthflows can dominate erosion and landscape evolution by supplying sediment to channels and controlling hillslope morphology to estimate the contribution of earthflows to regional sediment budgets and identify patterns of landslide activity earthflow movement needs to be quantified over significant spatial and temporal scales presently there is a paucity of data that can be used to predict earthflow behavior beyond the seasonal scale or over spatially extensive study areas across 226 km 2 of rapidly eroding franciscan complex rocks of the eel river catchment northern california we used a combination of lidar light detection and ranging and orthorectified historical aerial photographs to objectively map earthflow movement between 1944 and 2006 by tracking the displacement of trees growing on earthflow surfaces we find that 7 3 of the study area experienced movement over this 62 yr interval preferentially in sheared argillaceous lithology this movement is distributed across 122 earthflow features that have intricate elongate planform shapes a preferred south southwesterly aspect and a mean longitudinal slope of 31 the distribution of mapped earthflow areas is well approximated by a lognormal distribution with a median size of 36 500 m 2 approximately 6 of the study area is composed of earthflows that connect to major channels these flows generated an average sediment yield of 19 000 t km 2 yr 1 rock erosion rate of 7 6 mm yr over the 62 yr study period equating to a regional yield of 1100 t km 2 yr 1 0 45 mm yr if distributed across the study area as such a small fraction of the landscape can account for half of the regional denudation rate estimated from suspended sediment records 2200 t km 2 yr 1 or 0 9 mm yr we propose a conceptual model for long term earthflow evolution wherein earthflows experience intermittent activity and long periods of dormancy when limited by the availability of readily mobilized sediment on upper slopes ultimately high order river channels and ephemeral gully networks may serve to destabilize hillslopes controlling the evolution of earthflow prone terrain

fault zone controls on the spatial distribution of slow moving landslides slow moving landslides earthflows can dominate hillslope sediment flux and landscape erosion in hilly terrain with mechanically weak fine grained rock controls on the occurrence of slow moving landslides are poorly constrained and need to be understood for landscape evolution models sediment budgets and infrastructure and hazards planning here we use airborne interferometric synthetic aperture radar insar and aerial photographs to document 150 previously unidentified active earthflows along the central creeping portion of the san andreas fault california the earthflows move seasonally in response to winter rainfall occur on hillslopes at 20 40 gradients less than typically associated with rapid catastrophic landslides and have similar morphological characteristics to earthflows in different climatic and tectonic settings although our data extend up to 10 km from the fault trace 75 of detected landslides occur within 2 km of the active fault topographic precipitation and rock type metrics alone are not enough to explain the observed spatial distribution of earthflows instead we hypothesize that earthflows cluster near the creeping san andreas fault because of a fault induced zone of reduced bulk rock strength that increases hillslope susceptibility to failure in addition similar lithology topography and climate exist north of the creeping section of the fault yet earthflows there are rare this may be due to large magnitude earthquakes episodically triggering coseismic rapid landslides which preferentially remove weak rock from the fault damage zone our analysis suggests that the necessary conditions for earthflow formation in central california include some combination of reduced rock strength fine grained sedimentary rock threshold precipitation and relief and possibly the absence of large magnitude earthquakes these conditions likely hold for earthflow development in other areas and our work suggests that local variations in rock strength and seismicity such as those associated with fault zones need to be taken into account in order to accurately predict earthflow occurrence

a method for correcting geographically separated remanence directions for the purpose of archaeomagnetic dating summary spatial variations in the geomagnetic field must be taken into account if secular variation master curves and directional magnetic dates are to be optimized two methods for relocating remanence vectors have been proposed and in this paper their relative accuracies are compared using a numerical model based on the present day field a method which converts archaeomagnetic directions via a virtual geomagnetic pole is shown to be the more efficient transformation for an archaeomagnetic region the size of the british isles 900 km radius the maximum error in relocating vectors to a central location is predicted to be of the order of 1 2

holocene geomagnetic secular variation records from north eastern australian lake sediments summary secular variation records have been obtained from cores from lakes barrine and eacham two north eastern australian volcanic crater lakes the results from several cores have been stratigraphically correlated and then stacked and smoothed the chronology provided by radiocarbon dating indicates that the lake eacham sequence spans the last 5700 calendar years the time scale for the lake barrine record is less weil constrained but it

shallow methane hydrate system controls ongoing downslope sediment transport in a low velocity active submarine landslide complex hikurangi margin new zealand morphological and seismic data from a submarine landslide complex east of new zealand indicate flow like deformation within gas hydrate bearing sediment this creeping deformation occurs immediately downslope of where the base of gas hydrate stability reaches the seafloor suggesting involvement of gas hydrates we present evidence that contrary to conventional views gas hydrates can directly destabilize the seafloor three mechanisms could explain how the shallow gas hydrate system could control these landslides 1 gas hydrate dissociation could result in excess pore pressure within the upper reaches of the landslide 2 overpressure below low permeability gas hydrate bearing sediments could cause hydrofracturing in the gas hydrate zone valving excess pore pressure into the landslide body 3 gas hydrate bearing sediment could exhibit time dependent plastic deformation enabling glacial style deformation we favor the final hypothesis that the landslides are actually creeping seafloor glaciers the viability of rheologically controlled deformation of a hydrate sediment mix is supported by recent laboratory observations of time dependent deformation behavior of gas hydrate bearing sands the controlling hydrate is likely to be strongly dependent on formation controls and intersediment hydrate morphology our results constitute a paradigm shift for evaluating the effect of gas hydrates on seafloor strength which given the widespread occurrence of gas hydrates in the submarine environment may require a reevaluation of slope stability following future climate forced variation in bottom water temperature

the search for a topographic signature of life landscapes are shaped by the uplift deformation and breakdown of bedrock and the erosion transport and deposition of sediment life is important in all of these processes over short timescales the impact of life is quite apparent rock weathering soil formation and erosion slope stability and river dynamics are directly influenced by biotic processes that mediate chemical reactions dilate soil disrupt the ground surface and add strength with a weave of roots over geologic time biotic effects are less obvious but equally important biota affect climate and climatic conditions dictate the mechanisms and rates of erosion that control topographic evolution apart from the obvious influence of humans does the resulting landscape bear an unmistakable stamp of life the influence of life on topography is a topic that has remained largely unexplored erosion laws that explicitly include biotic effects are needed to explore how intrinsically small scale biotic processes can influence the form of entire landscapes and to determine whether these processes create a distinctive topography

widespread initiation reactivation and acceleration of landslides in the northern california coast ranges due to extreme rainfall episodically to continuously active slow moving landslides are driven by precipitation climate change which is altering both the frequency and magnitude of precipitation worldwide is therefore predicted to have a major impact on landslides here we examine the behavior of hundreds of slow moving landslides in northern california in response to large changes in annual precipitation that occurred between 2016 and 2018 we quantify the landslide displacement using repeat pass radar interferometry and pixel offset tracking techniques on a novel data set from the airborne nasa jpl uninhabited aerial vehicle synthetic aperture radar we found that 312 landslides were moving due to extreme rainfall during 2017 compared to 119 during 2016 which was the final year of a historic multiyear drought however with a return to below to average rainfall in 2018 only 146 landslides remained in motion the increased number of landslides during 2017 was primarily accommodated by landslides that were smaller than the landslides that remained active between 2016 and 2018 furthermore by examining a subset of 51 landslides we found that 49 had increased velocities during 2017 when compared to 2016 our results show that slow moving landslides are sensitive to large changes in annual precipitation particularly the smaller and thinner landslides that likely experience larger basal pore water pressure changes based on climate model predictions for the next century in california which include increases in average annual precipitation and increases in the frequency of dry to wet extremes we hypothesize that there will be an overall increase in landslide activity

regolith production and transport at the susquehanna shale hills critical zone observatory part 2 insights from meteoric 10be 1 regolith mantled hillslopes are ubiquitous features of most temperate landscapes and their morphology reflects the climatically biologically and tectonically mediated interplay between regolith production and downslope transport despite intensive research few studies have quantified both of these mass fluxes in the same field site here we present an analysis of 87 meteoric 10be measurements from regolith and bedrock within the susquehanna shale hills critical zone observatory ssho in central pennsylvania meteoric 10be concentrations in bulk regolith samples n 73 decrease with regolith depth comparison of hillslope meteoric 10be inventories with analyses of rock chip samples n 14 from a 24 m bedrock core confirms that 80 of the total inventory is retained in the regolith the systematic downslope increase of meteoric 10be inventories observed at ssho is consistent with 10be accumulation in slowly creeping regolith 0 2 cm yr 1 regolith flux inferred from meteoric 10be varies linearly with topographic gradient determined from high resolution light detection and ranging based topography along the upper portions of hillslopes at ssho however regolith flux appears to depend on the product of gradient and regolith depth where regolith is thick near the base of hillslopes meteoric 10be inventories at the north and south ridgetops indicate minimum regolith residence times of 10 5 3 7 and 9 1 2 9 ky respectively similar to residence times inferred from u series isotopes in ma et al 2013 the combination of our results with u series derived regolith production rates implies that regolith production and erosion rates are similar to within a factor of two on ssho hillcrests

holocene history of earthflow mass movements in south central british columbia the influence of hydroclimatic changes large earthflows in south central british columbia have exhibited regionally consistent fluctuations in their movement during the holocene over the past 60 years air photographs show that many earthflows were reactivated during the relatively wet period 1950 1985 over the past 300 years a fairly coherent relationship is established between periods of wetter climate defined by the tree ring record and phases of slope movement defined by the record of compression wood development in conifers located near earthflow headscarps on a time scale of several thousand years stratigraphic evidence shows that many large earthflows in the region underwent significant reactivation of movement in the post mazama period during the relatively wet cool neoglacial interval of the holocene these lines of evidence indicate that holocene hydroclimatic changes have exerted an important influence on the regimen of large earthflows earthflows present a wealth of paleogeomorphic information hitherto largely neglected

rainfall ground water flow and seasonal movement at minor creek landslide northwestern california physical interpretation of empirical relations simple ground water flow analyses can clarify complex empirical relations between rainfall and landslide motion here we present detailed data on rainfall ground water flow and repetitive seasonal motion that occurred from 1982 to 1985 at minor creek landslide in northwestern california and we interpret these data in the context of physically based theories we find that landslide motion is closely regulated by the direction and magnitude of near surface hydraulic gradients and by waves of pore pressure caused by intermittent rainfall diffusive propagation of pore pressure waves accompanies downward ground water flow along nearly vertical hydraulic gradients that exist in most of the landslide field data combined with a pore pressure diffusion analysis show that single rainstorms typically produce short period waves that attenuate before reaching the landslide base in contrast seasonal rainfall cycles produce long period waves that modify basal pore pressures but only after time lags that range from weeks to months such tune lags can depend on antecedent moisture storage and can explain variable delays between the onset of the wet season and seasonal landslide motion limit equilibrium analysis shows that when seasonal pressure waves reach the landslide base they establish a critical distribution of effective stress that delicately triggers landslide motion the critical effective stress balance is extremely sensitive to the direction and magnitude of hydraulic gradients although pervasively downward gradients instigate seasonal motion we infer from theory and limited data that ground water also may circulate locally in near surface cells the circulation can further reduce the landslide s frictional strength particularly in areas of nearly horizontal ground water flow that occur beneath steep faces of hummocks hummocky topography that results from slope instability may therefore cause ground water flow that perpetuates instability

lake sediment record of the geomagnetic secular variation in britain during holocene times summary a palaeomagnetic record of the geomagnetic secular variation during the last 10000 years has been obtained from 10 cores of sediment from loch lomond scotland lake windermere north england and llyn geirionydd north wales a time scale is provided by 30 radiocarbon age determinations and pollen analyses on several of the cores the main swings and much fine detail of both declination and inclination records repeat well between cores and between lakes and the overall record is much more detailed than previous european records the new record shows that neither declination nor inclination swings have been periodic over the past 10000 years but that the main swings have become progressively shorter in duration during that time each swing is characterized by fine detail which enables use of the record as a secondary method of dating other european sediments the motion of the geomagnetic vector has been predominantly clockwise throughout the time period spanned but confirms a period of anticlockwise motion from 1100 to 600 bp first discovered by british archaeomagnetic investigations the record agrees with british and czechoslovakian archaeomagnetic records but not with japanese archaeomagnetic or north american lake sediment records this suggests that the secular changes are controlled by local growing and decaying drifting sources rather than by wobbling of the main geomagnetic dipole

influence of anthropogenic land use change on hillslope erosion in the waipaoa river basin new zealand european settlement of the poverty bay region resulted in deforestation and conversion of 90 of the landscape to pastureland the resulting loss of vegetation triggered a rapid increase in hillslope erosion as widespread landslide complexes and gully systems developed on weak lithologic units in the waipaoa basin to quantify the rate and volume of historic hillslope degradation we used a 1956 2010 sequence of aerial photographs for a 16 km2 catchment to map temporal changes in the spatial extent of active landslides then we created a turf index based on the extent and style of pastoral ground disruption which correlates with downslope velocity based on the movement of trees and other features we assigned average velocities to the turf classes as follows 1 minimal disrupted ground 0 6 m yr 2 a mix of disrupted ground and intact blocks 3 4 m yr and 3 no intact blocks or vegetation 6 m yr we then calculated the average annual sediment flux using these turf derived velocities the width of the landslide channel intersection and an average toe depth of 4 4 1 3 m mean standard deviation sd from 37 field measurements the resulting catchment averaged erosion rates are mean sd 29 9 12 9 mm yr 1956 28 8 13 7 mm yr 1969 13 4 4 9 mm yr 1979 17 0 6 2 mm yr 1988 and 9 9 3 6 mm yr 2010 compared with long term post 18 ka erosion rates 1 6 mm yr and the long term uplift rate 1 mm yr for this site the 50 year anthropogenically driven rate is an order of magnitude larger 20 mm yr previously we measured an increase in erosion over the past 3 4 kyr 2 2 mm yr and here we demonstrate this increase could be primarily due to human land use change showing that a century of rapid erosion superimposed on the background geologic rate can profoundly skew the interpretation of erosion rates copyright 2016 john wiley sons ltd

controls on the seasonal deformation of slow moving landslides article history precipitation drives seasonal velocity changes in slow moving landslides by increasing pore water pressure and reducing the effective normal stress along basal shear zones this pressure change is often modeled as a pore water pressure wave that diffuses through the landslide body such that the minimum time required for landslides to respond to rainfall should vary as the square of landslide depth which often approximates the saturated thickness and inversely with hydraulic diffusivity here we assess this model with new observations from the landslide prone eel river catchment northern california using satellite radar interferometry insar time series precipitation data and high resolution topographic data from airborne lidar we quantify the seasonal dynamics of 10 slow moving landslides which share the same lithologic tectonic and mediterranean climate conditions these slope failures have areas ranging from 0 16 to 3 1 km 2

large area landslide detection and monitoring with alos palsar imagery data over northern california and southern oregon usa abstract multi temporal alos palsar images are used to automatically investigate landslide activity over an area of 200 km by 350 km in northern california and southern oregon interferometric synthetic aperture radar insar deformation images insar coherence maps sar backscattering intensity images and a dem gradient map are combined to detect active landslides by setting individual thresholds more than 50 active landslides covering a total of about 40 km 2 area are detected then the short baseline subsets sbas insar method is applied to retrieve time series deformation patterns of individual detected landslides down slope landslide motions observed from adjacent satellite tracks with slightly different radar look angles are used to verify insar results and measurement accuracy comparison of the landslide motion with the precipitation record suggests that the landslide deformation correlates with the rainfall rate with a lag time of around 1 2 months between the precipitation peak and the maximum landslide displacement the results will provide new insights into landslide mechanisms in the pacific northwest and facilitate development of early warning systems for landslides under abnormal rainfall conditions additionally this method will allow identification of active landslides in broad areas of the pacific northwest in an efficient and systematic manner including remote and heavily vegetated areas difficult to inventory by traditional methods

surface ages and weathering rates from 10be meteoric and 10be 9be insights from differential mass balance and reactive transport modeling abstract to reconstruct the dynamic evolution of weathered material at the earth s surface requires techniques that record the fluxes of material into and out of the weathering zone cosmogenic isotopes formed in situ within the earth s surface or in the atmosphere meteoric are important chronometers for both time and fluxes meteoric 10 be has been used to evaluate surface ages soil residence times and rates of sediment transport however the meteoric 10 be dating tool relies on complete retention of 10 be on mineral surfaces within the weathered regolith an assumption that will not be valid where soil ph is low or mineral surface area available for sorption is lacking here we evaluate whether the stable isotope of 9 be that is released upon weathering reactive be can be used to correct for 10 be mobility this approach relies on the inventory of reactive 9 be in the weathering zone as a measure of the mass depletion whereas the 10 be inventory is a function of age to explore the spatial and temporal relationship between the be isotopes we use a multi component reactive transport model framework to evaluate a set of differential mass balance equations for the 10 be 9 be composition of the bulk solid and sorbed reservoirs on non eroding surfaces we first find that the 10 be 9 be reac is inversely proportional to the long term chemical weathering rate even in cases of incomplete be retention second we find that coupling 10 be and 9 be to provide a tool for surface age dating 10 be is complex because incomplete retention affects each isotope to a different extent beryllium 10 is supplied at the surface of soil where sorption onto secondary minerals is more extensive while 9 be is released from primary minerals at the weathering front where secondary minerals are less abundant if 9 be loss is less than about 15 we find 9 be inventories can be used to reliably correct 10 be inventories to within 10 the error associated with the correction also increases with increasing age and thus the correction is more favorable for younger surfaces over longer timescales the error on the age introduced by the loss correction using 9 be is magnified whereas the error associated with uncorrected ages decreases because the 10 be is more strongly retained as chemical weathering progresses we also find that the reactive transport model confirms a set of simple mass balance descriptions providing guidance for future data collection collectively the modeling results suggest that measurement of be isotopes in weathered regolith provides a unique approach to determine both surface ages and chemical weathering rates

geomorphic coupling between hillslopes and channels in the swiss alps the coupling relationships between hillslope and channel network are fundamental for the understanding of mountainous landscapes evolution here we applied dendrogeomorphic methods to identify the hillslope channel relationship and the sediment transfer dynamics within an alpine catchment at the highest possible resolution the schimbrig catchment is located in the central swiss alps and can be divided into two distinct geomorphic sectors to the east the schimbrig earth flow is the largest sediment source of the basin while to the west the rossloch channel network is affected by numerous shallow landslides responsible for the supply of sediment from hillslopes to channels to understand the connectivity between hillslopes and channels and between sources and sink trees were sampled along the main rossloch stream on the schimbrig earth flow and on the rossloch depositional area geomorphic observations and dendrogeomophic results indicate different mechanisms of sediment production transfer and deposition between upper and lower segments of the channel network in the source areas upper part of the rossloch channel system sediment is delivered to the channel network through slow movements of the ground typical of earth flow shallow landslides and soil creep contrariwise in the depositional area lower part of the channel network the mechanisms of sediment transfer are mainly due to torrential activity floods and debris flows tree analysis allowed the reconstruction of periods of high activity during the last century for the entire catchment the collected dataset presents a very high temporal resolution but we encountered some limitations in establishing the source to sink connectivity at the catchment wide scale despite these uncertainties for decennial timescales the results suggest a direct coupling between hillslopes and neighbouring channels in the rossloch channel network and a de coupling between sediment sources and sink farther downstream with connections possible only during extraordinary events

estimating river sediment discharge to the ocean application to the eel margin northern california abstract hydrotrend a synthetic river discharge numerical model can simulate the natural variability daily annually and longer in the flux of water and sediment delivered to the coastal ocean the numerical model is designed to make discharge predictions based on climate even though field measurements of river flow are not available provided that appropriate assumptions are made regarding past climate the model can predict how a river may have behaved in the geological past sediment load is determined from a river s rating coefficients when applied to the flood dominated eel river northern california hydrotrend captures the intermonthly and interannual variability of discharge and loads over a century or more hydrotrend is applied to the ice age paleo eel river when sea level was lower and climate much cooler and wetter the paleo eel river at 18 000 year bp would see its hinterland runoff increase but not the magnitude of the peak discharges the post dicted sediment load of the paleo eel river was 25 greater than today s although basin precipitation was 45 greater and the hinterland area 4 greater through sea level lowering a method is provided to obtain sediment discharge rating coefficients for unmonitored modern rivers and paleo rivers the relationship q s g 1 2 h 3 2 a 1 2 provides for an estimate of a river s sediment load q s to within a factor of 3 over 7 orders of magnitude from knowledge of basin relief h and basin area a rating coefficients are determined from this estimate of q s and the power law rating curve q s aq b 1 where q is discharge

seasonal movement of the slumgullion landslide determined from global positioning system surveys and field instrumentation july 1998 march 2002 abstract measurements of landslide movement made by global positioning system surveys and extensometers over a 3 5 year period show that the slumgullion landslide in the san juan mountains of southwest colorado moved throughout the monitoring period but that daily velocities varied on a seasonal basis landslide velocities peaked in the early spring and summer in response to snowmelt and summer thunderstorms respectively velocities were slowest in mid winter when air and soil temperatures were coldest and precipitation was generally low and or in the form of snow with a low water content we hypothesize that the seasonal variability in velocities is due to ground water levels and corresponding pore pressures that decrease when surface water is unavailable or cannot infiltrate frozen landslide material and increase when surface water from melting snow or rainfall infiltrates unfrozen landslide material we also suggest that patches of bouldery debris and fractures created by continuous movement of the landslide are conduits through which surface water can infiltrate regardless of the frozen or unfrozen state of the landslide matrix material therefore the availability of surface water is more important than landslide temperature in controlling the rate of landslide movement this hypothesis is supported by field instrumentation data that show 1 landslide velocities coinciding with precipitation amounts regardless of the depth of freezing of landslide material 2 spring and annual landslide velocities that were greatest when the depth of freezing was also the greatest and 3 a rapid several weeks or less velocity and pore pressure response to rainfall the persistent but seasonally variable movement of the landslide fits the bathtub model for landslide movement described by baum and reid baum r l reid m e 2000 ground water isolation by low permeability clays in landslide shear zones in bromhead e n dixon n ibsen m l eds landslides in research theory and practice proc 8th int symp on landslides cardiff wales vol 1 139 144 in their model the landslide is isolated both mechanically and hydrologically from adjacent materials by low permeability clays these clays cause the landslide to retain water our data support this model by suggesting that pore pressures at the basal landslide surface are always adequate to maintain landslide movement and that any infiltration of water at the surface of the landslide is adequate to rapidly increase landslide velocity

kinematics of earthflows in the northern california coast ranges using satellite interferometry abstract slow moving landslides exhibit persistent downslope motion with variations in velocity driven by transient stress perturbations along the sliding surface here we use satellite insar and high resolution topographic data to identify 50 slow moving landslides in the northern california coast ranges and monitor their seasonal kinematics over 4 years these landslides have similar mechanical properties and are subject to the same external forcings which allows us to explore geometrical controls on kinematics to overcome errors associated with large deformation gradients we incorporate a deformation model in the insar processing that enables us to generate deformation time series we test our novel methodology using a synthetic deformation time series confirming our ability to resolve seasonal velocity patterns time series analysis of four representative landslides reveals that seasonal velocity changes are characterized by comparatively rapid acceleration and gradual deceleration each slide displays distinct kinematic zones with different mean velocities although velocity changes appear to occur synchronously along the landslide body over seasonal timescales because these deformation patterns are sensitive to subsurface geometry we employ a commonly used non newtonian viscous flow law to infer slide thickness and find that these slides likely exhibit a highly variable thickness and an irregular i e rough and non planar basal sliding surface our results suggest that slide geometry controls long term motion but does not strongly regulate their response to seasonal stress perturbations