assessment of rockfall susceptibility by integrating statistical and physically based approaches in val di fassa dolomites eastern italian alps rockfalls constitute the most significant gravity induced natural disaster that threatens both the inhabitants of the valley who are few and the thousands of tourists who populate the area in summer and winter to assess rockfall susceptibility we developed an integrated statistical and physically based approach that aimed to predict both the susceptibility to onset and the probability that rockfalls will attain specific reaches through field checks and multi temporal aerial photo interpretation we prepared a detailed inventory of both rockfall source areas and associated scree slope deposits using an innovative technique based on gis tools and a 3d rockfall simulation code grid cells pertaining to the rockfall source area polygons were classified as active or inactive based on the state of activity of the associated scree slope deposits the simulation code allows one to link each source grid cell with scree deposit polygons by calculating the trajectory of each simulated launch of blocks by means of discriminant analysis we then identified the mix of environmental variables that best identifies grid cells with low or high susceptibility to rockfalls among these variables structural setting land use and morphology were the most important factors that led to the initiation of rockfalls we developed 3d simulation models of the runout distance intensity and frequency of rockfalls whose source grid cells corresponded either to the geomorphologically defined source polygons geomorphological scenario or to study area grid cells with slope angle greater than an empirically defined value of 37 empirical scenario for each scenario we assigned to the source grid cells an either fixed or variable onset susceptibility the latter was derived from the discriminant model group active inactive membership probabilities comparison of these four models indicates that the geomorphological scenario with variable onset susceptibility appears to be the most realistic model nevertheless political and legal issues seem to guide local administrators who tend to select the more conservative empirically based scenario as a land planning tool

microstructural controls and the role of graphite in matrix porphyroblast exchange during synkinematic andalusite growth in a granitoid aureole in the contact metamorphic aureole of the tinaroo batholith north queensland australia mylonitic rocks were metamorphosed during a regional folding crenulation event d2 synchronous with the emplacement of muscovite bearing granitoids prismatic and skeletal andalusite porphyoblasts grew in carbonaceous schists mainly from the dissolution of staurolite muscovite quartz and biotite played a dual role in this reaction acting in a catalytic capacity as well as reactants or products staurolite was replaced by coarse grained muscovite biotite whereas andalusite locally replaced quartz muscovite biotite with diffusion of h al si mg fe and k ionic species linking sites of dissolution and growth graphite contributed to the reaction mechanism in a number of ways accumulations of graphite in front of advancing andalusite crystal faces led to skeletal growth and the formation of chiastolite structure where incremental growth occurred on adjacent 110 faces with subsequent filling in and inclusion of graphite along the diagonal zones the presence of graphite in some layers in the schist matrix prevented recrystallization of strained muscovite grains the muscovite grains in these layers in contrast to adjacent thin non graphitic layers were preferentially replaced by quartz this resulted in muscovite depletion haloes in graphitic layers around andalusite porphyroblasts somewhat arcuate zones of graphite concentrated during dissolution of quartz along a crenulation cleavage occur on some andalusite faces reactivation of the mylonitic foliation during the formation of d2 crenulations led to a preferential dissolution of quartz in zones of progressive shearing localized near andalusite porphyroblasts and hence the accumulation of graphite lack of deflection of the pre existing mylonitic foliation and anastomosing of the axial planes of d2 crenulations around andalusite porphyroblasts demonstrate not only the timing of growth but also that growing porphyroblasts do not push aside existing foliations

evidence of syndeformational contact metamorphism from porphyroblast matrix microstructural relationships abstract cordierite porphyroblasts in three high level contact metamorphic aureoles in southeast australia show microstructural evidence of having grown during the development of a crenulation foliation the evidence includes curvature of straight inclusion trails into crenulated matrix folia and deflection of matrix foliations including micaceous crenulation folia axial surfaces around porphyroblasts in some rocks coarsening has obliterated evidence of crenulations in the matrix owing to heating having outlasted deformation the crenulations are confined to the contact aureoles of granitoid plutons that have not undergone penetrative post intrusion deformation therefore the crenulations appear to have resulted from local deformation caused by the intrusion

optimal landslide susceptibility zonation based on multiple forecasts abstract environmental and multi temporal landslide information for an area in umbria italy was exploited to produce four single and two combined landslide susceptibility zonations the 78 9 km2 study area was partitioned in 894 slope units and the single susceptibility zonations were obtained through linear discriminant analysis lda quadratic discriminant analysis qda logistic regression lr and by training a neural network nn the presence or absence of landslides in the slope units in the period from pre 1941 to 1996 training set was used as the dependent variable for the terrain classification next adopting a regression approach two optimal combinations of the four single zonations were prepared the single and the combined zonations were tested against landslides in the 9 year period from 1997 to 2005 validation set different metrics were used to evaluate the quality of the susceptibility zonations including degree of model fit uncertainty in the probability estimates and model prediction skills these metrics showed that the degree of model fit was not a good indicator of the model forecasting skills zonations obtained through classical multivariate classification techniques lda qda and lr produced superior predictions when compared to the nn model that over fitted the landslide information in the training set lda and lr produced less uncertain zonations than qda and nn the combined models resulted in a reduced number of errors and in less uncertain predictions an important result that suggests that the combination of landslide susceptibility zonations can provide optimal susceptibility assessments

foliation development and refraction in metamorphic rocks reactivation of earlier foliations and decrenulation due to shifting patterns of deformation partitioning reactivation of early foliations accounts for much of the progressive strain at more advanced stages of deformation its role has generally been insufficiently emphasized because evidence is best preserved where por phyroblasts which contain inclusion trails are present reactivation occurs when progressive shearing operating in a synthetic anastomosing fashion parallel to the axial planes of folds changes to a combination of coarse and fine scale zones of progressive shearing some of which operate antithetically relative to the bulk shear on a fold limb reactivation of earlier foliations occurs in these latter zones reactivation decrenulates pre existing or just formed crenulations generating shearing along the decrenulated or rotated pre existing foliation planes partitioning of deformation within these foliation planes such that phyl losilicates and or graphite take up progressive shearing strain and other minerals accom modate progressive shortening strain causes dissolution of these other minerals this results in concentration of the phyllosilicates in a simi lar but more penetrative manner to the for mation of a differentiated crenulation cleavage except that the foliation can form or intensify on a fold limb at a considerable angle to the axial plane of synchronous macroscopic folds reactivation can generate bedding parallel schistosity in multideformed and meta morphosed terrains without associated folds heterogeneous reactivation of bedding gen erates rootless intrafolial folds with sigmoidal axial planes from formerly through going struc tures reactivation causes rotation or refrac tion of axial plane foliations forming in the same deformation event causing reactivation in those beds or zones in which an earlier foli ation has been reactivated and results in destruction of the originally axial plane foli ation at high strains reactivation also provides a simple explanation for the apparently wrong sense but normally observed rotation of gar net porphyroblasts whereby the external foli ation has undergone rotation due to antithetic shear on the reactivated foliation alter natively the rotation of the external foliation can be due to its reactivation in a subsequent deformation event porphyroblasts with inclusion trails com monly preserve evidence of reactivation of earl ier foliations and therefore can be used to ident ify the presence of a deformation that has not been recognized by normal geometric methods because of penetrative reactivation reac tivation often reverses the asymmetry between pre existing foliations and bedding on one limb of a later fold leading to problems in the geo metric analysis of an area when the location of early fold hinges is essential the stretching lineation in a reactivated foliation can be rad ically reoriented potentially causing major errors in determining movement directions in mylonitic schistosities in folded thrusts geometric relationships which result from reactivation of foliations around porphyroblasts can be used to aid determination of the timing of the growth of porphyroblasts relative to deformation events other aspects of reac tivation however can lead to complications in timing of porphyroblast growth if the presence of this phenomenon is not recognized for example d grown porphyroblasts may be dis solved against reactivated s and hence appear to have grown syn d

an estimate of kinematic vorticity from rotated elongate porphyroblasts internal fabric in strain shadows around elongate rutile porphyroblasts indicates rotation of porphyroblasts relative to the incremental stretching direction during deformation within a regional scale shear zone in south central alaska for porphyroblasts of various aspect ratios and initial orientations this fabric is used to assess the sense of rotation relative to the direction of maximum incremental stretching the total rotation and the vorticity the total rotation of porphyroblasts relative to the external fabric based on these parameters varies as a function of porphyroblast orientation all 111 porphyroblasts regardless of orientation have rotated in a clockwise sense relative to the external fabric comparison of these results with previous models suggests that the deformation which affected the porphyroblasts took place in the field of continuous forward rotation with a maximum ratio of the rate of pure shearing to the rate of simple shearing sr of 0 21 or a kinematic vorticity number wk 0 92 the model curves showing rotation vs final orientation do not vary significantly over the range of sr and r that is relevant to this study the data have significant scatter yet there is remarkable agreement between the data and the model for a of 1 5 these results illustrate how strain shadows around porphyroblasts with large aspect ratios and variable initial orientations provide a more complete assessment of kinematics than inclusion trails within more equant porphyroblasts

modelling of erosion processes associated with rainfall triggered lahars following the 2011 cordon caulle eruption chile abstract in this work we investigate the sheet and rill erosion process as a possible lahar initiation mechanism in two catchments located in villa la angostura argentina southern andes in association with the 2011 eruption of cordon caulle chile a few days after the climactic phase of the eruption several lahar events occurred in villa la angostura where 15 cm of tephra mantled the slopes the physically based model lisem openlisem 2013a b was applied to two small catchments where sheet and rill erosion of tephra deposits was observed model input parameters related to vegetation soil surface and infiltration were obtained from field measurements geotechnical tests and the literature a total of 20 scenarios were simulated using a range of values of rainfall intensity and duration and hydraulic conductivity only 16 of these scenarios resulted in erosion results show that hydraulic conductivity ks and rainfall intensity significantly affect the runoff volume with the smallest ks i e the tephra deposits associated with the largest fraction of fine ash being associated with the largest eroded volumes and the largest discharges of water and sediment the scenarios with the highest hydraulic conductivity did not show erosion for any modelled rainfall intensity nonetheless we conclude that sheet and rill erosion were not the principal mechanism for rain triggered lahars associated with the cordon caulle eruption but mostly shallow landslide and similar erosion mechanisms contributed to lahars in villa la angostura in fact the eroded volumes calculated with lisem are significantly smaller than the volume calculated with shallow landslide models for the same catchments trigrs

aureole deformation by flattening around a diapir during in situ ballooning the cannibal creek granite the cannibal creek granite a foliated pluton within a strongly deformed aureole shows several diagnostic features of a diapir the intensity of the aureole deformation diminished away from the contact the aureole foliation is continuous with that of the granite and forms closed elliptical trend lines and the contact metamorphic minerals are synkinematic with regard to the aureole foliation the pluton deformed its aureole in three stages involving initially brittle then ductile and finally brittle deformation styles initial intrusion of a low strength magma stoped kinked and flexed aside its overburden crystallization of the magma prevented further rise and it ballooned and deformed its aureole evidently entirely by ductile bulk shortening perpendicular to the contact this the major stage of aureole deformation records no evidence of vertical movement of the pluton or of progressive simple shear along its margin during this stage the magma may have been theologically a high strength bing

the role of debris supply conditions in predicting debris flow activity debris flow frequency and magnitude were determined for 33 basins in southwest british columbia basins were first classifiedaseitherweathering limitedortransport limitedusingadiscriminantfunctionbasedondebris contributingarea an area weighted terrain stability number and drainage density multiple regression was used to predict magnitude peak discharge frequency and activity frequency times magnitude within each group of basins model performance was improved by stratifying the total sample of debris flow basins into weathering and transport limited groups explained varianceincreasedbyanaverageof15percentinthetransport limitedsample indicatingthatsedimentsupplyconditionsin themoreactivebasinsarefundamentalinpredictingdebrisflowactivity anindependenttestoftheregressionmodelswith 11basinsyieldedgenerallygoodresultsfordebrisflowmagnitudeandpeakdischarge predictionofdebrisflowfrequency provedproblematicalinweathering limitedbasins themethodsdevelopedhereprovideestimatesofdebrisflowattributes in basins for which few data on past events are available copyright 1999 john wiley sons ltd

characteristics and mode of emplacement of gneiss domes and plutonic domes in central eastern pyrenees abstract gneiss domes and plutonic granitoid domes make up almost 50 of the pre hercynian terrains in the central and eastern pyrenees from a structural study of the shape and internal structure of the domes and of their relationships with the enclosing rocks it can be shown that both types of domes were emplaced diapirically during the major regional deformation phase and the peak of regional metamorphism the study also shows that the internal structure the overall shape and general behaviour relative to the host rocks are similar for plutonic domes and for gneiss domes this appears to be in good agreement with h ramberg s 1967 gravity deformation and the earth s crust academic press london 1970 model studies in relation to intrusion of plutonic bodies in mechanisms of igneous intrusion edited by newall g rast n geol j spec issue 2 261 286 model studies showing that dome or mushroom like structures similar to those observed develop when there is a small viscosity ratio between the rising body and its enclosing medium this implies a high crystal content for the granitoid magma this crystal content has been estimated by i calculating the viscosity and density in natural conditions from petrological data for the magma considered as a suspension using the model and program of j p carron et al 1978 bull soc geol fr 20 739 744 ii using the recent results of experimental deformation of partially melted granites of i van der molen m s paterson 1979 contr miner petrol 70 299 318 and ii comparing the preceding results with the data obtained by deformation experiments on rocks similar to those enclosing the domes the minimum crystal content for the development of a dome like structure has been thus estimated to about 70 i e a value very close to that estimated by van der molen paterson 1979 to be the critical value separating the granular framework flow from suspension like behaviour the effect of small variations in the viscosity of the rising body are then simulated by centrifuge experiments these small variations appear to exert a strong control on the shape and rate of rise of the domes they are thought to be sufficient to account for the variations in shape and structure and the level of emplacement of the different types of gneissic and plutonic domes finally more complex experiments with models built in order to simulate as closely as possible the natural structural evolution of the region as deduced from petrological and structural data are reported their implications for the regional interpretation of the relationships between gneissic and plutonic domes is then discussed

porphyroblast nucleation growth and dissolution in regional metamorphic rocks as a function of deformation partitioning during foliation development in regional metamorphic rocks the partitioning of deformation into progressive shearing and progressive shortening components results in strain and strain rate gradients across the boundaries between the partitioned zones these generate dislocation density gradients and hence chemical potential gradients that drive dissolution and solution transfer phyllosilicates and graphite are well adapted to accommodating progressive shearing without necessarily building up large dislocation density gradients within a grain because of their uniquely layered crystal structure however most silicates and oxides cannot accommodate strain transitions within grains without associated dislocation density gradients and hence are susceptible to dissolution and solution transfer as a consequence zones of progressive shearing become zones of dissolution of most minerals and of concentration of phyllosilicates and graphite exceptions are mylonites where strain rates are commonly high enough for plastic deformation to dominate over diffusion rates and therefore over dissolution and solution transfer porphyroblastic minerals cannot nucleate and grow in zones of active progressive shearing as they would be dissolved by the effects of shearing strain on their boundaries however they can nucleate and grow in zones of progressive shortening and this is aided by the propensity for microfracturing in these zones which allows rapid access of fluids carrying the material presumed to be necessary for nucleation and growth zones of progessive shortening also have a number of characteristics that help to lower the activation energy barrier for nucleation this includes a build up of stored strain energy relative to zones of progressive shearing in which dissolution is occuring porphyroblast growth is generally syndeformational and previously accepted criteria for static growth are not valid when the role of deformation partitioning is taken into account porphyroblasts in a contact aureole do not grow statically either as microfracturing associated with emplacement allows access of fluids in a fashion that is similar to microfracturing in zones of progressive shortening the criteria used for porphyroblast timing can be readily accommodated in terms of deformation partitioning reactivation of deforming foliations and a general lack of rotation of porphyroblasts with the spectacular exception of genuinely spiralling garnet porphyroblasts

physically based modelling of soil erosion induced by rainfall in small mountain basins abstract in coarse grained unsaturated soils heavy rainstorms may cause either shallow landslides or superficial soil erosion the triggering of both of these phenomena is related to infiltration runoff and overland flow which are key processes requiring investigation in particular the quantitative estimates of the sediment yield at the outlet of mountain basins requires suitable physically based modelling in this paper the available approaches to soil erosion analysis are first reviewed and the capabilities and limitations of a physically based model are then evaluated through a case study of two small mountain basins the results obtained are in good agreement with those in the literature and with specific field data from a test area specifically for distinct realistic rainfall scenarios soil suction is found to be a key factor in the spatial temporal evolution of infiltration and runoff inside a mountain basin and soil suction and rainfall intensity greatly influence the total peak discharge of water and sediments the maximum volumetric concentration of sediments transported by water to the outlet of a mountain basin is found to be primarily related to the basin s specific morphometry

late carboniferous syn tectonic magmatic flow at the northern margin of the north china craton evidence for the reactivation of cratonic basement abstract syn tectonic magmatic flow which typically occurs along continental margins or in orogenic belts deformed by tectonic stresses may indicate the re melting of middle lower crust tectonic setting of the magmatic plutons or the reactivation of cratonic basement the northern margin of the north china craton hosts late carboniferous plutons that show evidence of magmatic flow the plutons were emplaced at 320 300 ma as indicated by zircon u pb shrimp and la icp ms dating rather than high grade metamorphic rocks such as archean or paleoproterozoic gneiss as previously thought these granitic plutons composed of granite and granodiorite contain a south vergent shallow dipping transposition foliation and recumbent folds features of magmatic flow are overprinted by a north dipping foliation and solid state thrusting and shearing deformation aluminum in hornblende geobarometry shows that magmatic flow occurred in the middle to lower crust at a depth of approximately 19 5 km the occurrence of southward magmatic flow at 320 300 ma at the northern margin of the north china craton indicates the reactivation of cratonic basement

micromechanical modelling of rainsplash erosion in unsaturated soils by discrete element method abstract the rainsplash erosion is one important mechanism in natural and artificial slopes and the raindrops impact contributes to the amount of solids conveyed at the outlet of a mountain basin rainsplash erosion involves individual or small clusters of soil particles it is a dynamic temporally and spatially variable process and mainly occurs in unsaturated soils where capillarity forces allow steep slopes to be stable the discrete element method dem was firstly applied in this paper for the analysis of rainsplash erosion assuming realistic rainfall intensities and a range of both slope steepness and capillary forces in a parametric analysis the dem numerical results highlight the specific role of the slope steepness capillarity force and rainfall intensity towards the final volume of the solid eroded from the ground surface at the computational domain it is also valuable that the numerical results are in good agreement with literature formulations and increasing power law functions were found to relate well the eroded volume to rainfall intensity

oriented growth of sillimanite in andalusite placitas juan tabo area new mexico u s a in metapelitic schists near the sandia granite in the placitas juan tabo area new mexico nucleation sites for sillimanite are very variable but growth of sillimanite in andalusite is common either as bundles of fibrous fibrolitic sillimanite crystals or as coarser grained parallel prisms or dendritic crystals of sillimanite optical relationships indicate a coaxial relationship between the andalusite and the sillimanite but with a and b axes interchanged stacking faults formed by dissociated screw dislocations in the andalusite may have provided nucleation sites for sillimanite some large sillimanite grains appear to have formed by coarsening of fibrous sillimanite but others show no evidence of such coarsening some fibrous sillimanite occurs in folia in zones of inferred noncoaxial strain accumulation some occurs in radiating or crystallographically controlled aggregates in low strain zones between sillimanite folia these aggregates do not necessarily indicate postdeformation growth exce

landslide zoning over large areas from a sample inventory by means of scale dependent terrain units abstract a procedure is proposed to produce landslide distribution zoning maps to be considered preparatory to susceptibility hazard and risk zoning maps based on 1 the results from a statistical multivariate analysis of a landslide inventory which must be available for only a portion of the territory to be zoned and 2 the use of appropriately defined terrain mapping units the units are divided into terrain computational units tcus and terrain zoning units tzus whose size is related to the scale of zoning the procedure comprises three phases calibration validation and prediction the purpose of the prediction phase is the application of a calibrated and validated statistical model in a territory previously recognized as viable on the basis of a priori applicability maps for which no information is available regarding the distribution of landslides or where the information provided by the landslides inventory is unreliable or heterogeneous the proposed procedure is applied to two case studies in southern italy for the analysis and zoning of slow moving landslides at 1 25 000 and 1 100 000 scales respectively the first case study illustrates the applicability of the procedure the aim of the second case study is to address the part of the procedure related to the evaluation of the computational maps at the end of the calibration and validation phases

on erosion characteristics of compacted loess during wetting procedure under laboratory conditions the erosion of engineered slope surfaces has become an urgent problem in loess regions in china which has a serious impact on the safety and stability of the slope projects in this paper to study the effect of the confining pressure dry density of the slope surface and water flow velocity during wetting procedure on the erosion characteristics of compacted loess we developed a laterally confined uniaxial compression erosion apparatus which was characterized by the fact that it can change the confining pressure of the being eroded soil sample to analyze the loess erosion rates and particle size distributions of the eroded sediments the fractal dimensions of the eroded sediments were calculated by fractal theory and their variations were analyzed results show that the erosion rate is approximately linearly related to the confining pressure the higher pressure has a tendency to move towards the free top of soil sample the erosion rate increases compared with the water flow velocity the higher confining pressure plays a greater role in the erosion rate the influence of water flow velocity on the erosion rate decreases with the increase of dry density the erosion rate decreases the higher dry density enhances the ability of soil sample to resist water erosion the confining pressure changes the particle size distribution of the eroded sediments of loess samples the median diameter d50 increases however the fractal dimension decreases with the increase in confining pressure the confining pressure of slope surface has a negative effect on the loess anti erosion characteristics the results in this paper would provide detailed information on the mechanisms of loess erosion which could contribute toward prevention of surface erosion of high fill slopes in loess regions

recent glacial recession in the rwenzori mountains of east africa due to rising air temperature based on field surveys and analyses of optical spaceborne images landsat5 landsat7 we report recent decline in the areal extent of glaciers in the rwenzori mountains of east africa from 2 01 0 56 km 2 in 1987 to 0 96 0 34 km 2 in 2003 the spatially uniform loss of glacial cover at lower elevations together with meteorological trends derived from both station and reanalysis data indicate that increased air temperature is the main driver clear trends toward increased air temperatures over the last four decades of similar to 0 5 degrees c per decade exist without significant changes in annual precipitation extrapolation of trends in glacial recession since 1906 suggests that glaciers in the rwenzori mountains will disappear within the next two decades

the application of gis based logistic regression for landslide susceptibility mapping in the kakuda yahiko mountains central japan as a first step forward in regional hazard management multivariate statistical analysis in the form of logistic regression was used to produce a landslide susceptibility map in the kakuda yahiko mountains of central japan there are different methods to prepare landslide susceptibility maps the use of logistic regression in this study stemmed not only from the fact that this approach relaxes the strict assumptions required by other multivariate statistical methods but also to demonstrate that it can be combined with bivariate statistical analyses bsa to simplify the interpretation of the model obtained at the end in susceptibility mapping the use of logistic regression is to find the best fitting function to describe the relationship between the presence or absence of landslides dependent variable and a set of independent parameters such as slope angle and lithology here an inventory map of 87 landslides was used to produce a dependent variable which takes a value of 0 for the absence and 1 for the presence of slope failures lithology bed rock slope relationship lineaments slope gradient aspect elevation and road network were taken as independent parameters the effect of each parameter on landslide occurrence was assessed from the corresponding coefficient that appears in the logistic regression function the interpretations of the coefficients showed that road network plays a major role in determining landslide occurrence and distribution among the geomorphological parameters aspect and slope gradient have a more significant contribution than elevation although field observations showed that the latter is a good estimator of the approximate location of slope cuts using a predicted map of probability the study area was classified into five categories of landslide susceptibility extremely low very low low medium and high the medium and high susceptibility zones make up 8 87 of the total study area and involve mid altitude slopes in the eastern part of kakuda mountain and the central and southern parts of yahiko mountain

recognition classification and mechanical description of debris flows abstract various types of flow or mass movement involving water and sediments occur on steep slopes in mountainous areas among them debris flows are peculiar events during which a large volume of a highly concentrated viscous water debris mixture flows through a stream channel throughout the world these phenomena cause considerable damage but remain poorly understood although a basic knowledge is already available concerning their recognition and propagation firstly a synthesis of the useful practical criteria of recognition is proposed debris flows must be seen as intermediate phenomena between hyperconcentrated flows intense bed load transport and landslides separated from them by sharp transitions of some characteristics celerity deposit nature and flow type two parameters solid fraction and material type thought to be appropriate for a sound and practical classification are brought out and the corresponding complete classification of flow and mass movements in mountain areas is presented two extreme debris flow types are thus distinguished muddy debris flows and granular debris flows a critical review of recent advances in debris flow dynamic is then proposed it is pointed out that adequate work must be carried out in the field of non newtonian fluid mechanics in particular one fundamental rheological property of debris flow materials is the yield stress which explains thick deposits on steep slopes and can be inferred from field measurements furthermore it can be used to estimate viscous dissipation within the bulk during flow relevant models predicting muddy debris flow dynamics are already available whereas further progress is needed concerning granular flows

slope stability models for rainfall induced lahars during long lasting eruptions abstract in this study we analyse the spatial distribution of potential lahar sources during long lasting eruptions using two slope stability models shalstab and trigrs the analysis is based on observed deposit grain size and thickness rainfall data and slope angle of the lahar events in the area surrounding the cordon caulle volcano chile that occurred during the 2011 eruption the main phase of the eruption 4 7 june was characterized by eruptive plumes from 7 to 11 km high which dispersed most of the tephra eastward toward argentina with a total estimated volume of about 1 km3 tephra fallout blanketed the region from ese to ene of the volcano with the thickness of the tephra fallout layers between approximately 1 m 15 km from vent and 0 06 m 240 km from the vent on 10 june 2011 a major lahar occurred close to the argentina chile border that reached the national road 231 28 km from the vent three field campaigns were undertaken to collect samples and data from tephra fallout deposits and triggering mechanisms in the lahar source area model input parameters were obtained from geotechnical tests and field measurements several metrics were used for model evaluation and best fit to the data were obtained for simulations considering non cohesive ash layers for shalstab and a cohesion of 0 5 kpa for trigrs both models are sensitive to the physical properties of the tephra fallout deposit and the hydraulic and materiel strength properties of the study area they both also show good agreement with field data but provide different information trigrs provides an estimate of the timing based on a storm event and location of a potentially unstable area while shalstab simulations result in landslide susceptibility classes based on critical rainfall value these outcomes provide fundamental insights into lahar triggering during long lasting volcanic eruptions and are crucial to the compilation of lahar hazard maps and emergency management plans in the south andes volcanic region

spectral signature of alpine snow cover from the landsat thematic mapper mapping of snow and estimation of snow characteristics from satellite remote sensing data require that we distinguish snow from other surface cover and from clouds and compensate for the effects of the atmosphere and rugged terrain the spectral signature of the snowpack is calculated from a radiative transfer model accounting for scattering and absorption by the ice grains water inclusions and particulates in interpreting the spectral reflectance measured from the thematic mapper or from any other satellite we need to account for topographic effects without requiring that satellite data be precisely registered to digital elevation data because the poor quality of most digital elevation data introduces considerable noise into calculations of slope and azimuth for a range of snow types atmospheric profiles and topographic illumination conditions i estimate typical spectral signatures for the landsat thematic mapper tm images of the southern sierra nevada are analyzed to distinguish several classes of snow from other surface covers snow can be reliably distinguished from other surfaces and from clouds at all sun angles encountered in the mid latitudes in tm band 1 or 2 snow is brighter than other natural surfaces and in band 5 clouds are usually much more reflective than snow therefore the intersection of the following criteria maps the snow cover planetary reflectance rp in tm band 1 is greater than about 0 16 rp tm5 is less than about 0 2 the normalized band 2 5 difference rp tm2 rp tm5 rp tm2 rp tm5 is greater than about 0 4 large surface grain sizes can be distinguished from areas where the grain size is finer at the snow surface using tm bands 2 4 and 5 because of saturation in tm band 1 estimation of the degree of contamination by absorbing aerosols is not feasible rp tm2 rp tm5 rp tm2 rp tm5 is

dome emplacement and formation of kilometre scale synclines in a granite greenstone terrain quadrilatero ferrifero southeastern brazil the quadrilatero ferrifero is a portion of the brazilian precambrian shield containing a granite greenstone terrain characterized by granite gneiss domes encircled by kilometre scale synclines integration of porphyroblast matrix microtextures c axis fabrics analysis and strain analysis with outcrop scale structural relationships indicates that the main phase of domes and synclines evolution occurred during the westerly directed 0 8 0 6 ga pan african brasiliano regional shortening this tectonic event has produced the single pervasive foliation observed in the folded supracrustal sequences of the quadrilatero ferrifero dip slip ductile shear zones developed at the dome supracrustal interface are synchronous with dome evolution during the pan african brasiliano deformation as indicated by contemporaneous growth of aureole porphyroblasts in the shear planes these shear zones facilitated steeply directed downward flow of country rock material around the granite gneiss domes the marked density contrast between granite gneiss material and the iron rich supracrustals provided a gravitationally favourable environment for downward wallrock flow variations in shear zone kinematics away from the domes combined with kilometer scale viscous drag contributed to produce kilometre scale synclines in the supracrustal rocks constrained between upward moving domes

automated mapping of montane snow cover at subpixel resolution from the landsat thematic mapper a fully automated method uses landsat thematic mapper data to map snow cover in the sierra nevada and make quantitative estimates of the fractional snow covered area within each pixel we model winter and spring reference scenes as linear mixtures of image end member spectra to produce the response variables for tree based regression and classification models decision trees identify cloud cover and fractional snow covered area we test the algorithm on a different thematic mapper scene and verify with high resolution large format color aerial photography the accuracy of the automated classification of thematic mapper data equals that obtainable from the aerial photographs but is faster cheaper and covers a vastly larger area the mapping method is insensitive to the choice of lithologic or vegetation end members the water equivalent of the snow pack snow grain size or local illumination angle

the ardara pluton ireland deflating an expanded intrusion abstract the ardara pluton north western ireland is a circular monzodiorite granodiorite intrusion with a tail it has been regarded as a typical example of a pluton emplaced entirely by expansion balloning after initial intrusion most of the foliation in the pluton is magmatic with weak superimposed solid state features apart from a thin rind of strong solid state deformation the solid state deformation in the pluton appears to be largely if not entirely of post intrusive tectonic origin flattened microgranitoid enclaves a concentric magmatic flow foliation and compositional zoning in the pluton are consistent with some expansion of magma prior to crystallization however strains in the wall rocks indicate that only a small amount 25 38 of the volume of the pluton can be ascribed to ballooning this relatively small amount of expansion could account for a observed structural concordance and strong syn metamorphic deformation in the aureole b flattening of microgranitoid enclaves magma globules in the pluton and possibly c a small amount of solid state deformation in the pluton during lock up of magmatic flow evidence of solid state deformation superimposed on a strong magmatic flow foliation in the tail of the pluton implies that a fault was active during emplacement and may have assisted the intrusion further space for the pluton may have been made by a complex interaction of processes many of which cannot be constrained from a two dimensional cross section through the area these possibilities highlight the limitations of attempting to constrain emplacement mechanisms on the sole basis of structures adjacent to plutons

magmatic strains and foliation triple points of the merrimac plutons northern sierra nevada california implications for pluton emplacement and timing of subduction abstract cross cutting relationships between regional structures and post tectonic plutons of known age are commonly used to date regional deformation in orogenic belts in order to show that a pluton is post tectonic one must demonstrate that the strains within the pluton are not due to regional tectonic processes this paper reports strain measurements associated with pluton emplacement in northern sierra nevada these strain data and a microstructural analysis indicate that strains within the merrimac plutons are due to igneous not tectonic processes which strengthens the hypothesis that the plutons were emplaced after the formation of regional structures and melanges radiometric ages of the merrimac pluton in concert with structural data place a more reliable upper jurassic limit on the age of the subduction in the western belt of northern sierra nevada this paper also reports constrictional strains around plutons and suggests that the merrimac plutons contributed significantly to the ductile strains observed in the wall rocks

a review of criteria for the identification of magmatic and tectonic foliations in granitoids abstract foliations in granitoids can form by magmatic flow submagmatic flow high temperature solid state deformation and moderate to low temperature solid state deformation a review of previous work suggests that no single criterion can consistently distinguish foliations in granitoids formed by flow during ascent diapiric emplacement and expansion emplacement during regional deformation or regional deformation post dating emplacement however a magmatic origin is favoured for foliations defined by the alignment of igneous commonly euhedral minerals particularly where the foliation is parallel to internal or external pluton contacts foliations formed during expansion or ballooning of diapirs may be strictly magmatic in origin although some studies suggest that solid state deformation also may occur if so we would hope to find evidence of deformation of crystal melt systems and that the solid state deformation occurred at high temperatures the inference of syntectonic foliations is most convincing where magmatic and high temperature solid state foliations are subparallel these foliations are continuous with regionally developed foliations in the wall rocks synkinematic porphyroblasts are present in the wallrocks and igneous minerals have the same age as metamorphic minerals associated with the regional cleavage a strictly tectonic origin for foliations in granitoids is favoured when the foliation is defined by metamorphic minerals no alignment of igneous minerals occurs the foliation is locally at high angles to pluton wallrock contacts and the foliation is continuous with a regionally developed cleavage

analysis of three dimensional strain modified uniform distributions andalusite fabrics from a granite aureole a method of analysing finite strain from an initial random distribution of lines or planes is presented the shape of the strain ellipsoid is mapped to the eigenvalue ratios of an orientation matrix the method is used to interpret the andalusite fabrics from the aureole of the ardara granite county donegal ireland the high flattening strains determined in the aureole are accompanied by oblate strains in the granite margins and support the concept of deformation produced by expansion of the pluton

sequential porphyroblast growth and crenulation cleavage development during progressive deformation abstract six stages of crenulation cleavage development during a single deformation event d2 can be recognised in both matrix and porphyroblast inclusion trails in the robertson river formation n e australia these stages progress from undeformed to crenulation and differentiated crenulation of s1 through development of differentiated crenulation cleavage s2 and differentiated schistosity s2 to homogeneous foliation s2 these rocks underwent prograde metamorphism during d2 and chloritoid garnet staurolite andalusite and sillimanite isograds have been mapped most rocks are rich in porphyroblasts which commonly contain well defined inclusion trails the geometry of these trails varies from one mineral type to the next depending on the timing of porphyroblast growth relative to the stage of crenulation cleavage development in the schistose matrix the deformation history involved progressive bulk inhomogeneous shortening and the strain is very heterogeneous on all scales partly as a consequence of this hence each of the six stages of crenulation cleavage development formed locally at various times during d2 therefore if a porphyroblast grew late in the deformation it could overgrow all stages of crenulation cleavage development including the very early ones the temperature increased during metamorphism in any one locality and consequently some porphyroblasts overgrew others that were unstable in the new conditions preserving them from destruction hence the precise timing of mineralogical reactions deduced from isograds and mineral chemistry relative to the stages in schistosity development can also be determined in the andalusite zone the sequence of porphyroblasts in decreasing order of age is biotite garnet biotite staurolite andalusite dissolution of garnet occurred during growth of staurolite and especially andalusite and dissolution of staurolite accompanied andalusite growth

usage of high resolution landsat 7 band 8 for single band snow cover classification with the launch of landsat 7 a new band was added to the landsat enhanced thematic mapper plus etm the new panchromatic band 8 covers wavelengths of 0 52 0 92 m and extends over band 2 0 525 0 605 m band 3 0 630 0 690 m and band 4 0 750 0 900 m its high resolution with a pixel length of 15 m is of interest for high spatial resolution analysis this project focused on using landsat 7 band 8 as a precise tool to obtain remotely the size and shape of permanent snowpatches in the mountainous area west of abisko sweden in the supervised classification employed shadowed and non shadowed areas were classified separately supervision of the classification was based on ground truthing consisting of photographic mapping of the snow cover in the study area the results from this single band classification were compared to the results from the normalized difference snow index ndsi and false color images using bands 2 4 and 5 this comparison showed similar estimates of the total amount of snow covered area with the additional advantage that the landsat 7 band 8 lb8 classification detects details in the extent of individual snowfields this new application and the insights documented here support the use of landsat 7 band 8 for snow cover investigations in the future

some aspects of the initiation of debris avalanches in the campania region the role of morphological slope discontinuities and the development of failure abstract in may 1998 a prolonged period of rainfall caused disastrous landslides in the sarno quindici area campania southern italy the landslides initiated as small debris slides and developed into debris avalanches and debris flows involving the shallow pyroclastic deposits that lie on the steep vegetated slopes of this area in view of the potential for such events to occur again in this area an understanding of the initial failure mechanism is crucial if assessments are to be made of the hazard levels in this paper the results of detailed surveys of the morphological characteristics of the source areas are presented statistical analyses and parametrical relationships have been performed on key parameters demonstrating that the initial failures were associated with the presence of morphological discontinuities such as limestone scarps and road cuts notably the presence of man made cuts appears to have been responsible for about the 60 of the initial debris slides morphometric analysis has shown that the debris avalanches are characterised by a typical triangular shape statistical analyses have been used to try to relate the apex angles to relevant geomorphological parameters allowing for differences in local morphology the findings show some significant correlation

interference between pluton expansion and non coaxial tectonic deformation three dimensional computer model and field implications abstract structures in orogenic belts are greatly controlled by interactions between pluton related and tectonic related strain fields however many aspects of the geometry and evolution of these structures are poorly known for example 1 what is the geometry of these structures if regional deformation is coaxial 2 how does this geometry change with progressive deformation this paper describes a three dimensional simulation of strain shape and magnitude as well as foliation and lineation patterns formed by interactions between pluton expansion and homogeneous coaxial deformation this simulation suggests that interactions between pluton expansion and regional uniaxial shortening generate patterns that are distinct from the patterns produced by regional uniaxial extension or regional non coaxial deformation for example shortening produces doughnut shaped constrictional rings about the pluton whereas extension produces apple shaped flattening regions around the pluton in addition shortening produces one continuous doughnut shaped low strain region around the pluton on the other hand extension creates two separate ellipsoidal low strain regions at the ends of the pluton furthermore shortening forms foliation rings that have triangular two dimensional sections and lineation is concentric around the axis of maximum shortening in contrast extension produces two separate foliation and lineation cones at the ends of the pluton all these structural and strain elements migrate away from the pluton with increasing expansion rates and towards the pluton with increasing tectonic deformation rates although structural studies around plutons should always integrate microstructural radiometric and field measurements simulation generated patterns can be used to evaluate 1 origin geometry and evolution of structures around plutons 2 mechanisms that explain inclusion trails within porphyroblasts 3 contribution of pluton related strains to strains measured in the country rock and 4 type and three dimensional orientation of regional kinematic schemes

spatial and temporal occurrence of rainfall induced shallow landslides of flow type a case of sarno quindici italy article i nfo rainfall induced shallow landslides of flow type provide unstable masses which often travel long run out distances with high velocities thus posing a high societal risk when they affect large areas therefore analysis of their spatial and temporal occurrence is relevant to landslide hazard assessment as the first step of the risk analysis in order to address this issue this paper outlines a multidisciplinary procedure that is applied to the may 1998 sarno quindici landslides southern italy whose spatial and temporal occurrence is not satisfactorily addressed in current literature the spatial occurrence of the landslides is analysed using heuristic models for both the source and propagation areas the temporal occurrence of the landslides is firstly compiled and then related to the cumulated rainfall stratigraphy and hydraulic boundary conditions finally the spatial and temporal occurrence of the main landslide triggering mechanism is modelled over the whole affected area by analysing the groundwater regime and slope stability conditions the obtained results show that the spatial and temporal occurrence is strongly related to stratigraphy and hydraulic boundary conditions at both the slope and massif scales they also highlight a suitable procedure for assessing the spatial and temporal occurrence of complex landslides over large areas