salinity driven thermocline transients in a wind and thermohaline forced isopycnic coordinate model of the north atlantic abstract an isopycnic coordinate oceanic circulation model formulated with the aim of simulating thermodynamically and mechanically driven flow in realistic basins is presented special emphasis is placed on the handling of diabatic surface processes and on thermocline ventilation the model performance is illustrated by a 30 year spinup run with coarse horizontal resolution 2 mesh in a domain with north atlantic topography extending from 10 to 60 n latitude the vertical structure encompasses 10 isopycnic layers in steps of 0 2 units capped by a thermodynamically active mixed layer from an initially isohaline state with isopycnals prescribed by zonally averaged climatology the model is forced by seasonally varying wind stress radiative and freshwater fluxes and by a thermal relaxation process at the surface after a mechanical spinup time of about 15 years a quasi stationary pattern of mean circulation and annual variability ensues characterized by pronounced subtropical mode water formation

a physics based model to derive rainfall intensity duration threshold for debris flow a statistical method to establish an intensity duration curve i d curve for debris flows is highly dependent on a large amount of debris flows and rainfall events and is impossible for a gully lacking observation data to overcome this limitation a physics based model to derive the i d curve is presented in this new model the density of the debris flow is chosen as the key parameter based on which the rainfall intensity and duration necessary for fitting i d curve are obtained the physical model is validated in jiangjia gully a typical debris flow valley with several debris flows each year a series of i d curves under the conditions of different antecedent rainfalls were fitted these derived curves are similar to the shape of the curve from the statistical method but having upper and lower boundary lines related to the necessary conditions for the occurrence of debris flows the precision of the new model is identified as about 80 5 using 63 collected rainfalls in jiangjia gully in yunan province china this value is 27 7 higher than the curve fitted through the statistical method this new physical model is capable of improving the deficiency of the statistical method and has great application potential for predicting debris flows

tropical climates at the last glacial maximum a new synthesis of terrestrial palaeoclimate data i vegetation lake levels and geochemistry palaeodata in synthesis form are needed as benchmarks for the palaeoclimate modelling intercomparison project pmip advances since the last synthesis of terrestrial palaeodata from the last glacial maximum lgm call for a new evaluation especially of data from the tropics here pollen plant macrofossil lake level noble gas from groundwater and delta 18 o from speleothems data are compiled for 18 2 ka c 14 32 degrees n 33 degrees s the reliability of the data was evaluated using explicit criteria and some types of data were re analysed using consistent methods in order to derive a set of mutually consistent palaeoclimate estimates of mean temperature of the coldest month mtco mean annual temperature mat plant available moisture pam and runoff p e cold month temperature mat anomalies from plant data range from 1 to 2 k near sea level in indonesia and the s pacific through 6 to 8 k at many high elevation sites to 8 to 15k in s china and the se usa mat anomalies from groundwater or speleothems seem more uniform 4 to 6 k but the data are as yet sparse a clear divergence between mat and cold month estimates from the same region is seen only in the se usa where cold air advection is expected to have enhanced cooling in winter regression of all cold month anomalies against site elevation yielded an estimated average cooling of 2 5 to 3 k at modern sea level increasing to approximate to 6 k by 3000m how ever neotropical sites showed larger than the average sea level cooling 5 to 6 k and a non significant elevation effect whereas w and s pacific sites showed much less sea level cooling 1 k and a stronger elevation effect these findings support the inference that tropical sea surface temperatures ssts were lower than the climap estimates but they limit the plausible average tropical sea surface cooling and they support the existence of climap like geographic patterns in sst anomalies trends of pam and lake levels indicate wet lgm conditions in the w usa and at the highest elevations with generally dry conditions elsewhere these results suggest a colder than present ocean surface producing a weaker hydrological cycle more arid continents and arguably steeper than present terrestrial lapse rates such linkages are supported by recent observations on freezing level height and tropical ssts moreover simulations of greenhouse and lgm climates point to several possible feedback processes by which low level temperature anomalies might be amplified aloft

lithological and seasonal control on rainfall thresholds for the possible initiation of landslides in central italy we compiled a catalogue of 442 rainfall events with landslides in the abruzzo marche and umbria regions central italy between february 2002 and august 2010 for each event we determined the duration d in hours and the cumulated total event rainfall e in mm using rainfall measurements obtained from a dense network of 150 rain gauges landslides were mapped as single points using google earth and were attributed a level of mapping accuracy p in four classes p1 1 km2 p10 10 km2 p100 100 km2 p300 300 km2 using this information we determined cumulated event rainfall rainfall duration ed thresholds which are entirely equivalent to rainfall intensity duration id thresholds and avoid unnecessary conversions to determine the ed thresholds we modified a statistical method first proposed to determine id thresholds adopting a bootstrapping statistical technique we expanded the method to determine the uncertainty associated with the parameters that define the power law threshold model and the sensitivity of the thresholds to the number of d e data points in the empirical data set we determined ed thresholds for 1 and 5 exceedance probability levels i for the entire study area and for the three individual regions in the study area abruzzo marche and umbria ii for three main lithological domains in the study area post orogenic sediments flysch deposits carbonate rocks and iii for two seasonal periods may september october april comparison of the ed thresholds indicates that the cumulated amount of rainfall necessary to trigger landslides in flysch deposits is larger than in post orogenic sediments and carbonate rocks however the ed thresholds for post orogenic sediments and carbonate rocks were statistically indistinguishable in the study area also the seasonal thresholds were statistically different for rainfall durations shorter than 12 h and longer than 100 h but were indistinguishable in the range 12 d 100 h the results obtained are directly applicable to landslide forecasting based on empirical rainfall thresholds and have implications for landslide hazard and risk assessment as well as for landslide erosion and landscape evolution studies both in the study area and in the neighboring regions

dynamical and observational constraints on tropical pacific sea surface temperatures at the last glacial maximum asynchronously coupled atmosphere and ocean general circulation model simulations are used to examine the consequences of changes in the west east sea surface temperature sst gradient across the equatorial pacific at the last glacial maximum lgm simulations forced by the climap sst for the lgm where the west east sst gradient across the pacific is reduced compared to present produce a reduction in the strength of the trade winds and a decrease in the west east slope of the equatorial thermocline that is incompatible with thermocline depths newly inferred from foraminiferal assemblages stronger than present trade winds and a more realistic simulation of the thermocline slope are produced when eastern pacific ssts are 2 c cooler than western pacific ssts our study highlights the importance of spatial heterogeneity in tropical ssts in determining key features of the glacial climate

internal soil moisture and piezometric responses to rainfall induced shallow slope failures summary better knowledge regarding internal soil moisture and piezometric responses in the process of rainfall induced shallow slope failures is the key to an effective prediction of the landslide and or debris flow initiation to this end internal soil moisture and piezometric response of 0 7 m deep 1 5 m wide 1 7 m high and 3 94 m long semi infinite sandy slopes rested on a bi linear impermeable bedrock were explored using a chute test facility with artificial rainfall applications the internal response time defined by the inflection point of the soil moisture and piezometric response curves obtained along the soil bedrock interface were closely related to some critical failure states such as the slope toe failure and extensive slope failures it was also found that the response times obtained at the point of abrupt bedrock slope decrease can be used as indicators for the initiation of rainfall induced shallow slope failures an investigation of spatial distributions of soil water content or degrees of saturation s r in the slope at critical failure states shows that the 0 2 m below surface zone remains unsaturated with s r 40 60 regardless of their distances from the toe and the rainfall intensity non uniform distributions of or s r along the soil bedrock interface at critical failure states were always associated with near saturation states s r 80 100 around the point of bedrock slope change or around the transient toe upstream of the slumped mass induced by the retrogressive failure of the slope these observations suggest the important role of the interflow along the soil bedrock interface and the high soil water content or high porewater pressure around the point of bedrock slope deflection in the rainfall induced failure of sandy slopes consisting of shallow impermeable bedrocks the present study proposes an internal response time criterion to substantiate the prediction of rainfall induced shallow slope failures it is believed that the internal response time reflects the overall characteristics of a slope under rainfall infiltration and can be as useful as the conventional meteorology based threshold times the internal response time theory can be generalized via numerical modeling of slope hydrology slope geology and slope stability in the future

critical rainfall for typhoon induced debris flows in the western foothills taiwan abstract typhoon morakot devastated taiwan during august 6 11 2009 with a maximum total rainfall of 2884 mm causing 22 000 cases of slope failures rainfall thresholds for debris flow initiation are investigated using the hourly intensity vs duration i d hourly intensity vs cumulative rainfall i r and daily rainfall vs antecedent daily rainfall adr index methods among the 39 well documented cases 32 sites with known date and time of debris flow initiation were focused results reveal that debris flows and debris avalanches occur under a very wide range of rainfall characteristics with return periods ranging from several years to 200 years indicating that the empirical rainfall threshold alone is insufficient for an effective debris flow prediction system a consistent pattern of all i r paths for the investigated sites shows the combined effect of rainfall characteristics and inherent stability features of the slopes suggesting that the i r path is potentially useful in facilitating debris flow predictions it is also suggested that empirical rainfall thresholds should be calibrated using physical models against specific slope conditions to increase the accuracy of debris flow predictions

recognition of high frequency sea level fluctuations in proterozoic siliciclastic tidal deposits mount isa australia metre scale cyclicity is uncommon in siliciclastic sediments unlike in carbonates fischer plots of shallow subtidal to intertidal siliciclastic cycles of proterozoic age from australia reveal systematic thickening and thinning patterns that after correcting for tectonic subsidence loading and compaction are compatible with a eustatic origin both 1 5 m y and 0 25 0 50 m y period sea level changes are recognizable the longer period curves are asymmetric and indicate rapid rises followed by slow falls in sea level predictable facies and grain size trends are associated with different slopes on the longer period curve fischer plots provide an appropriate method for recognizing ecstatic effects in siliciclastic sediments that are less sensitive to sea level changes than carbonates

experimental investigation of rainfall criteria for shallow slope failures a theory of the internal response based rainfall criterion for predicting slope failure is proposed based on artificial rainfall tests for a sandy slope key elements in a generic model describing shallow slope failure are identified from the tests with extensive soil moisture and piezometric measurements the observed retrogressive slope failure was triggered by a toe failure followed by an abrupt increase in debris discharge the onset of the failure was preceded by a clear transition point on the soil moisture vs time curve at the soil bedrock interface both external and internal responses of slopes to rainfall can be expressed using widely adopted i d rainfall intensity duration plots experimental results from the tests indicate close relationships between the internal based and external based i d envelopes for critical slope states the theory of the internal based i d criterion proposed here will be useful for more accurate slope failure predictions

the determination of statistical and deterministic hydrological landslide triggering thresholds hydrological landslide triggering thresholds separate combinations of daily and antecedent rainfall or of rainfall intensity and duration that triggered landslides from those that failed to trigger landslides they are required for the development of landslide early warning systems when a large data set on rainfall and landslide occurrence is available hydrological triggering thresholds are determined in a statistical way when the data on landslide occurrence is limited deterministic models have to be used for shallow landslides directly triggered by percolating rainfall triggering thresholds can be established by means of one dimensional hydrological models linked to the infinite slope model in the case of relatively deep landslides located in topographic hollows and triggered by a slow accumulation of water at the soil bedrock contact simple correlations between landslide occurrence and rainfall can no longer be established therefore real time failure probabilities have to be determined using hydrological catchment models in combination with the infinite slope model

initiation conditions for debris flows generated by runoff at chalk cliffs central colorado abstract we have monitored initiation conditions for six debris flows between may 2004 and july 2006 in a 0 3 km 2 drainage basin at chalk cliffs a band of hydrothermally altered quartz monzonite in central colorado debris flows were initiated by water runoff from colluvium and bedrock that entrained sediment from rills and channels with slopes ranging from about 14 to 45 the availability of channel material is essentially unlimited because of thick channel fill and refilling following debris flows by rock fall and dry ravel processes rainfall exceeding i 6 61 d 0 77 where i is rainfall intensity mm h and d is duration h was required for the initiation of debris flows in the drainage basin the approximate minimum runoff discharge from the surface of bedrock required to initiate debris flows in the channels was 0 15 m 3 s colluvium in the basin was unsaturated immediately prior to antecedent and during debris flows antecedent volumetric moisture levels in colluvium at depths of 1 cm and 29 cm ranged from 4 9 and 4 7 respectively during debris flows peak moisture levels in colluvium at depths of 1 cm and 29 cm ranged from 10 20 and 4 12 respectively channel sediment at a depth of 45 cm was unsaturated before and during debris flows antecedent moisture ranged from 20 22 and peak moisture ranged from 24 38 although we have no measurements from shallow rill or channel sediment we infer that it was unsaturated before debris flows and saturated by surface water runoff during debris flows our results allow us to make the following general statements with regard to debris flows generated by runoff in semi arid to arid mountainous regions 1 high antecedent moisture levels in hillslope and channel sediment are not required for the initiation of debris flows by runoff 2 locations of entrainment of sediment by successive runoff events can vary within a basin as a function of variations in the thickness of existing channel fill and the rate of replenishment of channel fill by rock fall and dry ravel processes following debris flows and 3 rainfall and simulated surface water discharge thresholds can be useful in understanding and predicting debris flows generated by runoff and sediment entrainment

modeling shallow landsliding susceptibility by incorporating heavy rainfall statistical properties abstract we present an index based shallow landsliding susceptibility model which allows explicit incorporation of local heavy rainfall statistical properties the model called quasi dynamic shallow landsliding model qd slam is developed upon a theory for coupled shallow subsurface flow and landsliding of the soil mantle the model uses a quasi dynamic wetness index to predict the spatial distribution of soil saturation in response to a rainfall of specified duration and can take into account the spatial variability of soil properties the rainfall predicted to cause instability in each topographic element is characterized by intensity and duration the incorporation of a scaling model for the rainfall frequency duration relationship provides a parsimonious and robust way to include heavy rainfall statistical properties into shallow landsliding modeling the model is used to determine the return period of the critical rainfall needed to cause instability for each topographic element the model is validated over six different study sites where detailed inventories of shallow landslides are available two study sites are located in the north of taiwan and four are located in the italian alps the sites are characterized by different climates and by different duration of the landslide triggering storms model results are evaluated against the surveyed landslides and compared to those obtained by using a steady state model resembling shalstab it is shown that qd slam improves significantly over the steady state approach in predicting existing landslides as represented in the considered landslide inventory moreover the improvement is higher for the cases where the landslide triggering storm duration is short with respect to the length of time required for every point on a catchment to reach subsurface drainage equilibrium the results of our work highlight the capability of the model to incorporate a robust description of the heavy rainfall properties in the analysis and mapping of shallow landsliding susceptibility by using an index style approach

triggering conditions and mobility of debris flows associated to complex earthflows landslides on black marl slopes of the french alps are in most cases complex catastrophic failures in which the initial structural slides transform into slow moving earthflows under specific hydrological conditions these earthflows can transform into debris flows due to their sediment volume and their high mobility debris flow induced by landslides are far much dangerous than these resulting from continuous erosive processes a fundamental point to correctly delineate the area exposed to debris flows on the alluvial fans is therefore to understand why and how some earthflows transform into debris flow while most of them stabilize in this paper a case of transformation from earthflow to debris flow is presented and analysed an approach combining geomorphology hydrology geotechnics and rheology is adopted to model the debris flow initiation failure stage and its runout postfailure stage using the super sauze earthflow alpes de haute provence france as a case study the objective is to characterize the hydrological and mechanical conditions leading to debris flow initiation in such cohesive material results show a very good agreement between the observed runout distances and these calculated using the debris flow modeling code cemagref 1 d the deposit thickness in the depositional area and the velocities of the debris flows are also well reproduced furthermore a dynamic slope stability analysis shows that conditions in the debris source area under average pore water pressures and moisture contents are close to failure a small excess of water can therefore initiate failure seepage analysis is used to estimate the volume of debris that can be released for several hydroclimatic conditions the failed volumes are then introduced in the cemagref 1 d runout code to propose debris flow hazard scenarios results show that clayey earthflow can transform under 5 year return period rainfall conditions into 1 km runout debris flow of volumes ranging between 2000 to 5000 m 3 slope failures induced by 25 year return period rainfall can trigger large debris flow events 30 000 to 50 000 m 3 that can reach the alluvial fan and cause damage

late pleistocene paleoclimatology of the central equatorial pacific sea surface response to the southeast trade winds proxy indicators of sea surface temperature and equatorial divergence based on radiolarian assemblage data and of trade wind intensity based on eolian grain size data show similar aspects of variability during the late pleistocene all indicators fluctuate at higher frequencies than the 100 000 year glacial interglacial cycle display reduced amplitude variations since 300 000 years ago exhibit a change in the record character at about 300 000 years ago the mid brunhes climatic event and have higher amplitude variations in sediments 300 000 850 000 years old time series analyses were conducted to determine the spectral character of each record 18o of planktonic foraminifer sea surface temperature values equatorial divergence indicators and wind intensity indicators and to quantify interrecord coherence and phase relationships the record was divided at the 300 000 year clear change in climatic variability nonstationarity the 18o based time scale is better lower in the core so our spectral analyses concentrated on the interval from 402 000 774 000 years the 18o spectra show 100 000 and 41 000 year power in the younger portion 0 300 000 years and 100 000 41 000 and 23 000 year power in the older interval all highly coherent and in phase with the specmap average stacked isotope record unlike the isotope record the dominant period in both the eolian grain size and equatorial divergence indicators is 31 000 years this period is also important in the sea surface temperature signal where the dominant spectral peak is 100 000 years the 31 000 year spectral component is coherent and in phase between the eolian and divergence records confirming the link between atmospheric and ocean surface circulation for the first time in the paleoclimate record since the 31 000 year power appears in independent data sets within this core and also appears in other equatorial records j imbrie personal communication 1987 we assume it to be real and representative of both a nonlinear response to orbital forcing possibly a combination of orbital tilt and eccentricity and some resonance phenomenon required to amplify the response at this period so that it appears as a dominant frequency component the mid brunhes climatic event is an important aspect of these records but its cause remains unknown

catastrophic landslide induced by typhoon morakot shiaolin taiwan abstract typhoon morakot induced the catastrophic and deadly shiaolin landslide in southern taiwan on 9 august 2009 resulting in more than 400 casualties we undertook a geological and geomorphological investigation with the aim of reconstructing the events leading up to this landslide and to clarify factors that contributed to its development cumulative rainfall reached up to 1676 5 mm in about three days under the influence of the typhoon and the shiaolin landslide with a volume of 25 106 m3 occurred one day after the peak in rainfall intensity the landslide occurred on a dip slope overlying late miocene to early pliocene sedimentary rocks consisting of silty shale massive mudstone and sandstone it started as a rockslide in the upper third of the landslide area and transformed into a rock avalanche that crossed a series of terraces and displaced or buried the village below it buried the riverbed of the chishan river and ran up the opposite slope creating a landslide dam 60 m high which was breached about 1 h and 24 min later flooding the village the velocity of the landslide is estimated to have been 20 4 to 33 7 m s 1 and its apparent friction angle was 14 which indicates its high mobility the detachments in the source area consist of combinations of bedding planes and joints or faults the landslide was preceded by gravitational deformation which appeared as hummocky landforms before the landslide and as buckle folds exposed after the event the landslide deposits consist of fragments of mudstone shale and sandstone as well as clayey material at its base this clayey material consisting of illite chlorite quartz feldspar and calcite is assumed to have strongly influenced the long rapid runout

terrestrial conditions at the last glacial maximum and climap sea surface temperature estimates are they consistent climap 1981 seasonal reconstruction of the earth s surface at the last glacial maximum geological society of america map and chart series mc 36 boundary conditions were used as inputs to the giss general circulation model and the last glacial maximum lgm climate was simulated for six model years the simulation was compared with snow line depression and pollen inferred temperature data at low latitudes specifically for hawaii colombia east africa and new guinea the model does not produced as much cooling at low latitudes as is implied by the terrestrial evidence an alternative experiment in which the climap sea surface temperatures were uniformly lowered by 2 c produces a better fit to the land data although in hawaii model temperatures are still too warm the relatively warm climap tropical sea surface temperatures also provide for only a slight decrease in the hydrologic cycle in the model in contrast to both evidence of lgm tropical aridity and the results of the experiment with colder ocean temperatures with the climap sea surface temperatures the lgm global annual mean surface air temperature is 3 6 c colder than at present if the ocean temperatures were allowed to cool in conformity with the model s radiation balance the lgm simulation would be 5 6 c colder than today and in better agreement with the tropical land evidence

a warning system for rainfall induced shallow failures abstract it is widely recognised that soil slips and debris flows are triggered by short intense storms owing its geologic geomorphologic and climatic settings the piedmont region nw italy is highly prone to the occurrence of this kind of landslides in the last two centuries in fact a total of 105 severe meteoric events which triggered shallow failures occurred and of these 18 events took place from 1990 to 2002 a fair number of rainfall thresholds have been proposed in the literature defined both on empirical or on physical bases empirical thresholds are defined collecting rainfall data for landslide meteoric events and for events without landslides while physical thresholds are based on numerical models that consider the relation between rainfall pore pressure and slope stability the main objective of this paper is the identification of the empirical triggering thresholds for the piedmont region four meteoric events were selected and analysed november 4 5 1994 july 7 8 1996 april 27 30 2000 october 13 16 2000 because they supply a wide range of variation for both rainfall parameters duration intensity cumulative rainfalls and the number of induced landslides in the intensity duration plot the critical limit is described by the equation i 19d 0 50 where i rainfall intensity expressed in mm h and d rainfall duration expressed in hours such a limit is traced to envelop 90 of the points on the graph in the ni d diagram the triggering thresholds are given by the equations ni 0 76d 0 33 and ni 4 62d 0 79 where ni normalised intensity with respect to the annual precipitation map expressed in mm h pma 100 in the article the different meaning of these thresholds is discussed finally the diagram ni ncr is proposed the triggering threshold is given by the expression ni 0 09ln ncr 0 54 where ncr is the normalised cumulative critical rainfall mm pma 100 the application of the triggering thresholds as a fundamental element in a warning system dedicated to the safeguarding of population in landslide prone areas is discussed in detail an operating procedure which is presently being verified and tested in the studied area is described

an integrated model for predicting rainfall induced landslides this study proposes a novel method that combines a deterministic slope stability model and a statistical model for predicting rainfall induced landslides the method first uses the deterministic model to derive the rainfall rate critical to induce slope failure for each land unit then it calculates the difference between the critical rainfall threshold and estimated rainfall intensity using the difference and estimated rainfall duration as explanatory variables the method derives a logit integrated model to compute landslide occurrence probabilities to demonstrate the effectiveness of this method the study used radar rainfall estimates and landslides associated with a typhoon tropical cyclone to develop the integrated model and the same types of data associated with another typhoon to validate the model the model had a modified success rate of 84 0 for predicting landslides and stable areas and model validation yielded a modified success rate of 87 4 both rates were better than those from the critical rainfall model the main advantage of the integrated model lies in its use of rainfall variables that are not included in calculating the critical rainfall also as a probabilistic model the integrated model is better suited for decision making in watershed management this study has advanced the method for predicting rainfall triggered landslides

internal soil moisture response to rainfall induced slope failures and debris discharge article i nfo predictions of rainfall induced fast moving mass flow and or debris flows require better knowledge of the mechanism controlling the debris discharge of slopes in debris source areas a series of rainfalltests on 0 32 m deep 0 7 m high 1 35 m wide sandy slopes resting on a bi linear impermeable rigid base was performed soil moisture content and solid discharge measurements were performed to gain insights into the rainfall induced retrogressiveslopefailure thesolid ordebris dischargeisaresultof thewash outof the fluidizedslopetoeby the interflow along the soil bedrock interface characteristics of the failure process for the slopes are represented by mass wasting curves or solid discharge qs vs time t curves which are functions of the rainfall intensity and or the cumulative rainfall the mass wasting curves have inflection points representing transitions from minor toe failures into remarkable retrogressive failures the first inflection point of the soil moisture vs t curve measured at the soil bedrock interface signaling the arrival of the descending wet front may serve as a precursor for predicting the onset of an abrupt solid discharge induced by shallow slope failures the time of peak water content measured at the soil bedrock interface may approximate the time of 5 total solid volume discharge up to the time of 5 of total slope volume discharge a fully saturated state sr 100 was never observed at the 0 2 m below surface zone however it was observed along the soil bedrock interfaceat near toezoneof the slope regardlessof theintensityof rainfallinvestigated retrogressive failures were essentially associated with nonuniformly distributed water content in the slope for both the 0 2 m below surface zone and the soil bedrock interface a more uniform distribution of sr along the full height of the slope was found for slopes subjected to high rainfall intensities of 47 and 65 mm h than that for the slope subjected to a low rainfall intensity of 23 mm h at the inflection point of the qs vs t curve and 5 of total solid volume discharge values of sr at a certain distance from the toe for the soil bedrock interface were higher than those measured at the same distance fromthe toefor the 0 2 m below surface zone indicating the effect of infiltration induced interflowalong the soil bedrock interface and its effects on the fluidization of the slope toe and the retrogressive failure of the slope

relationship between the initiation of a shallow landslide and rainfall intensity duration thresholds in japan abstract the empirical rainfall intensity and duration i d threshold for the initiation of shallow landslide is newly defined for japan where heavy rainfalls frequently occur during the east asian summer monsoon season the rainfall causes sediment related disasters annually this paper presents an examination of 1174 rainfall induced shallow landslides that occurred during 2006 2008 their i d conditions were analyzed objectively from rainfall data radar raingauge analyzed precipitation to derive the i d threshold using the quantile regression method i 2 18 d 0 26 where i is measured in millimeters per hour and d in hours as measured from the beginning of rainfall to the landslide occurrence rainfall events are separated by the absence of rainfall for 24 h we then established a rescaled i d threshold by dividing the rainfall intensity by the mean annual precipitation map as imap 0 0007 d 0 21 where imap is the rescaled average per hour rainfall intensity these thresholds were defined by the second percentile regression line for d of 3 537 h the new thresholds are considerably lower than those previously reported for the world humid subtropical regions the asian monsoon region and japan the result suggests that japan is highly prone to rainfall induced shallow landslides because of its high relief topography geologic conditions human interference and rainfall characteristics during the east asian summer monsoon season

late pleistocene paleoclimatology of the central equatorial pacific a quantitative record of eolian and carbonate deposition detailed records of vso 6i3c percentage and mass accumulation rate of caco and eolian percentage mass accumulation rate and grainsize generated for core rcl l 210 from the equatorial pacific reveal the timing of paleoclimatic events over the past 950 000 yr the caco percentage record shows the standard pacific correlation of high caco content with glacial periods but displays a marked change of character about 490 000 yr ago with older stages showing much less variability the carbonate mass flux record however does not show such a noticeable change sedimentation rates vary from about 0 5 to 3 0 cm l000 yr and during the past 490 000 yr sections with enhanced sedimentation rates correspond to periods of high caco percentage eolian mass accumulation rates an indication of the aridity of the source region are usually higher during glacial times eolian grainsize an indication of the intensity of atmospheric circulation generally fluctuates at a higher frequency than the loo ooo yr glacial cycle the mid brunhes climatic event centered at 300 000 yr ago appears as a 50 000 yr interval of low intensity and reduced variability of atmospheric circulation furthermore the nature of this entire record changes then with the younger portion indicating less variation in wind intensity than the older part of the record the late matuyama increase in amplitude of paleoclimatic signals begins 875 000 yr ago in the eolian record 25 000 yr before the 6i80 and caco percentage amplitude increases about

regionalization of rainfall thresholds an aid to landslide hazard evaluation rainfall soil properties and morphology are major factors controlling shallow landsliding a series of meteorological events that triggered soil slips in northern italy were studied to define rainfall thresholds and to evaluate a possible regionalization soil properties triggering rainfall and local lithological and morphometrical settings of different sites were used as input to an infiltration model the approach allows the recognition of several triggering conditions in the piedmont pre alpine and alpine regions this suggests the need for different rainfall thresholds with respect to those derived with other methods intensity versus rainfall duration relationships become particularly important when related to soil permeability and thickness and demonstrate the role of antecedent precipitation events with exceptional water discharge from obstructed road culverts reveal the role played by anthropic structures in triggering such phenomena different approaches to slope stability analysis are shown taking into account bedrock lithology topography seepage and local saturation conditions

estimating temporal probability for landslide initiation along transportation routes based on rainfall thresholds abstract the estimation of the temporal probability of landslide initiation is an essential component in landslide hazard assessment in this paper a temporal probability model is presented for the initiation of shallow translational debris slides and debris flows along cut slopes of a railroad sector in southern india for which an extensive landslide database was available covering a time span of 15 years the model is based on rainfall thresholds and gives the likelihood of occurrence of rainfall that can trigger landslides with a certain density the temporal probability was calculated as the joint probability of annual exceedance probability of the rainfall threshold determined using a poisson probability model and the probability of landslide occurrence once the threshold had been exceeded the model was tested for a 19 km long railroad alignment in the nilgiri hills which was divided into a number of sections on the basis of terrain characteristics a landslide inventory containing dates of occurrence was prepared from historical records for the period 1987 to 2007 daily rainfall for the same period was collected from 15 rain gauges rainfall thresholds were established for the sections based on the relationship between daily and antecedent rainfalls four thresholds were defined for rainfall events that can trigger one or more landslides within each section and one threshold that can trigger 15 or more landslides along the entire route the annual temporal probability varies from 0 27 to 0 49 the model was also found useful in predicting landslides in a nearby road with similar characteristics the result indicates that more than 60 of the recorded landslides along the road occurred within the sections with high temporal probability values 0 40 the temporal probability derived from the model forms the basis for future landslide risk analysis along the transportation routes