shear stress in the graphitization of carbonaceous matter during the low grade metamorphism from the northern parang mountains south carpathians implications to graphite geothermometry abstract low grade metamorphic rocks from the northern parang mountains south carpathians were examined to infer the temperature of metamorphism and to obtain new data to study the applicability of the geothermometers relying on the graphite crystallinity to rocks that underwent different shear stress conditions there were analyzed samples of graphitic carbonaceous matter bearing rocks that exposed dissimilar degrees of strain for which the temperature of metamorphism was calculated using the graphite geothermometers based on the lattice parameter c0 determined through x ray diffractometry and based on the peak area ratio of the first order raman spectrum the temperature was also inferred from the chemical composition of the chlorite and from the fe mg partitioning between chlorite and chloritoid the mineral chemistry being determined through electron microprobe analyses the results obtained have shown i differences of up to more than 150 c between vicinal strained and less strained zones when applying the geothermometers based on the graphite crystallinity and ii considerable discrepancies between the temperatures calculated based on the graphite crystallinity and those based on the chlorite and chloritoid chemical compositions these inconsistencies are most likely caused by the fact that the calibration of the graphite geothermometers considers temperature as being exclusively responsible for enhancing the degree of graphite crystallinity and therefore these graphite geothermometers should be adjusted accordingly by introducing a correction factor that quantifies the degree of strain of the samples analyzed in order to obtain more accurate results

graphitization of carbonaceous matter during metamorphism with references to carbonate and pelitic rocks of contact and regional metamorphisms japan this study is an attempt to correlate the graphitization process of carbonaceous matter during metamorphism with metamorphic grade graphitization can be parameterized using crystal structure and chemical and isotopic compositions the extent of graphitization could be characterized mainly by temperature duration of metamorphism and rock composition we compared the graphitization trends for two metamorphic terrains a contact aureole of the kasuga area and a regional metamorphic terrain of high temperature low pressure type of the ryoke metamorphic terrain in northern kiso area central japan and for two different lithologies carbonate and pelite using x ray diffractogram dta tg analysis and chemical and stable isotope analyses during contact metamorphism graphitization and carbon isotopic exchange reactions proceeded simultaneously in pelitic and carbonate rocks the decreases in basal spacing d 002 of the carbonaceous matter in carbonate rocks is greatly accelerated at temperatures higher than about 400 c furthermore carbon isotopic ratios of graphite in carbonate rocks also change to 13c enriched values implying exchange with carbonates the beginning of this enrichment of 13c in the carbonaceous matter coincides with an abrupt increase of the graphitization processes carbon isotopic shifting up to 5 in pelites could be observed as metamorphic temperature increased probably by about 400 c carbonaceous matter in pelitic rocks is sometimes a mixture of poorly crystallized organic matter and well crystallized graphite detritus dta tg analysis is an effective tool for the distinction of detrital graphitic material two sources for the original carbon isotopic composition of carbonaceous matter in pelites in the kasuga contact aureole can be distinguished about 28 and 24 regardless of the presence of detrital graphite and were mainly controlled by depositional environment of the sediments graphitization in limestones and pelitic rocks in regional metamorphism proceeds further than in a contact aureole in the low temperature range the differences in extent of graphitization between the two metamorphic regions is large however at temperatures higher than 600 c the extent of graphitization in both regions is indistinguishable the degree of graphitization is different in limestones and pelitic rocks from the ryoke metamorphic terrain we demonstrate that the graphitization involves a progressive re construction process of the crystal structure the sequence of the first appearance of crystal inter planar spacing correlates with the metamorphic grade and indicates the crystal growth of three dimensional structured graphite

organic metamorphism as a key for reconstructing tectonic processes a case study from the austroalpine unit eastern alps at the northwestern margin of the gurktal alps eastern alps eoalpine cretaceous thrusting of carbonaceous material cm bearing metasediments formed a very low to low grade metamorphic nappe stack above higher grade metamorphic basement nappes sedimentary burial as well as progressive metamorphism transformed the enclosed cm to anthracite metaanthracite and semigraphite in a kinematically well constrained section at the northwestern frontal margin of the nappe stack this transformation has been investigated by vitrinite reflectance measurements and raman spectroscopy of carbonaceous materials rscm automated interactive fitting of raman spectra estimates the metamorphic peak temperatures in a complete section through the upper part of the upper austroalpine unit a rscm trend indicates a temperature profile of ca 250 600 c the top part of the gradient is reconstructed by one dimensional thermal modeling the certainty of ca 25 c at a confidence level of 0 9 resembles the data variability within a sample location due to the large calibration range the method is able to reconstruct a thermal crustal profile in space and time the study highlights the versatility of rscm which characterizes almost 250 ma of a complex and polyphase tectonic history rscm data characterize the variscan metamorphic grade in nappes now imbricated in the eoalpine nappe stack they additionally constrain a numerical model which emphasizes the significance of an increased thermal gradient in a continental margin towards the western neotethyan ocean during permo triassic lithospheric extension it finally characterizes the eoalpine metamorphic gradient during nappe stacking and a significant metamorphic jump related to exhumation and normal faulting

using multiple logistic regression and gis technology to predict landslide hazard in northeast kansas usa abstract landslides in the hilly terrain along the kansas and missouri rivers in northeastern kansas have caused millions of dollars in property damage during the last decade to address this problem a statistical method called multiple logistic regression has been used to create a landslide hazard map for atchison kansas and surrounding areas data included digitized geology slopes and landslides manipulated using arcview gis logistic regression relates predictor variables to the occurrence or nonoccurrence of landslides within geographic cells and uses the relationship to produce a map showing the probability of future landslides given local slopes and geologic units results indicated that slope is the most important variable for estimating landslide hazard in the study area geologic units consisting mostly of shale siltstone and sandstone were most susceptible to landslides soil type and aspect ratio were considered but excluded from the final analysis because these variables did not significantly add to the predictive power of the logistic regression soil types were highly correlated with the geologic units and no significant relationships existed between landslides and slope aspect

thermal springs in lake baikal pore waters extracted from sediment cores were analyzed for their oxygen and hydrogen isotopic compositions and major ion chemistry to determine the source of water from a vent area for diffuse lake bottom thermal springs or seeps in frolikha bay northeastern lake baikal the delta sup 18 o values of pore waters range from minus 15 2 per thousand to minus 16 7 per thousand and delta d values range from minus 119 per thousand to minus 126 per thousand both isotopes determined relative to standard mean ocean water smow bottom water in lake baikal has a delta sup 18 o value of minus 5 6 per thousand and a delta d values of minus 120 per thousand pore waters in the vent area are significantly enriched in mg k ca and especially na and have the lowest delta d and delta sup 18 o values these pore waters are isotopically and chemically distinct from pore waters in other more typical parts of the lake the pore water isotopic data fall on a local meteoric water line and covariations in water isotopes and chemistry are not consistent with evaporation or hydrothermal water rock interaction the thermal springs represent discharging meteoric waters that have been gently heated during subsurface circulation and are largely unaltered isotopically chemical variations are most likely due to dissolution of subsurface evaporites

autologistic modelling of susceptibility to landsliding in the central apennines italy in previous research a logistic regression of landslide occurrence on several explanatory variables was fitted and used to map landslide susceptibility for a small area in the central apennines italy here the spatial dependence or spatial correlation in the residuals from the fitted regression model was accounted for by inserting an autocovariate into the model the autocovariate was estimated by applying a gibbs sampler to the susceptibilities for neighbouring pixels as in any landslide susceptibility analysis accuracy was difficult to assess because of the requirement for data on future landslides however by comparing the ordinary logistic model to the autologistic model obtained on the same set of data it was possible to assess the influence of the autocovariate the autocovariate rendered the model simpler because several variables lost their significance and were therefore omitted from the model further areas of high landslide susceptibility estimated from the autologistic model were geographically clustered as one would expect and this may be advantageous in terms of i interpreting the model and ii displaying the results to non experts

mountain building in taiwan a thermokinematic model the taiwan mountain belt is classically viewed as a case example of a critical wedge growing essentially by frontal accretion and therefore submitted to distributed shortening however a number of observations call for a significant contribution of underplating to the growth of the orogenic wedge we propose here a new thermokinematic model of the taiwan mountain belt reconciling existing kinematic thermometric and thermochronological constraints in this model shortening across the orogen is absorbed by slip on the most frontal faults of the foothills crustal thickening and exhumation are sustained by underplating beneath the easternmost portion of the wedge tananao complex tc where the uplift rate is estimated to 6 3 mm a 1 and beneath the westernmost internal region of the orogen hsueshan range units hr where the uplift rate is estimated to 4 2 mm a 1 our model suggests that the tc units experienced a synchronous evolution along strike despite the southward propagation of the collision it also indicates that they have reached a steady state in terms of cooling ages but not in terms of peak metamorphic temperatures exhumation of the hr units increases northward but has not yet reached an exhumational steady state presently frontal accretion accounts for less than 10 of the incoming flux of material into the orogen although there is indication that it was contributing substantially more 80 before 4 ma the incoming flux of material accreted beneath the tc significantly increased 1 5 ma ago our results also suggest that the flux of material accreted to the orogen corresponds to the top 7 km of the upper crust of the underthrust chinese margin this indicates that a significant amount 76 of the underthrust material has been subducted into the mantle probably because of the increase in density associated with metamorphism we also show that the density distribution resulting from metamorphism within the orogenic wedge explains well the topography and the gravity field by combining available geological data on the thermal and kinematic evolution of the wedge our study sheds new light onto mountain building processes in taiwan and allows for reappraising the initial structural architecture of the passive margin

correlation between optical chemical and micro structural parameters of high rank coals and graphite abstract in order to identify the parameters that best characterize the chemical and structural evolution of organic matter during coalification the relationships between optical chemical and micro structural parameters in high rank coals and natural graphite were studied the samples include anthracites from penarroya belmez espiel basin spain douro basin portugal and alto chicama basin peru and natural graphite from canada mozambique and austria correlations between the following optical parameters were assessed vitrinite random reflectance rr reflectance indicating surfaces ris axis rmax rint and rmin and ris parameters ram rev and rst as well as bw and ai anisotropy parameters furthermore the chemical parameters used were chosen according to their significant variation in coals namely volatile matter carbon and hydrogen contents calculated in dry ash free basis vmdaf cdaf hdaf as well as the h c atomic ratio structural organization was characterized by micro raman spectroscopy and xrd raman parameters used were the full width at half maximum fwhm and position of g and d1 bands on the first order raman spectrum and the id1 ig intensity area ratio the selected xrd parameters were interlayer spacing d002 and crystallite sizes la and lc results show that i rmax ris axis seems to correlate best with chemical and micro structural parameters ii for the majority of studied samples hdaf and h c atomic ratio are the only chemical parameters with significant correlations with rmax iii the fwhm of the g band of raman spectrum shows good linear correlation with the xrd parameter d002 and iv structural organization of carbon materials as measured by trends in their optical and crystalline parameters is influenced by their hydrogen content daf basis and therefore by the h c atomic ratio

metamorphic rates in collisional orogeny from in situ allanite and monazite dating the prograde sequence of rare earth minerals recorded in metapelites during regional metamorphism reveals a series of irreversible reactions among silicates and phosphates in individual samples from the northern lepontine central alps allanite is partly replaced by monazite at 560 580 c relic allanite retains its characteristic growth zoning acquired at greenschist facies conditions 430 450 c coexisting monazite and allanite were dated in situ to delimit in time successive stages of the barrovian metamorphism in situ sensitive high resolution ion microprobe shrimp u th pb dating of allanite 31 5 1 3 and 29 2 1 0 ma and monazite 18 0 0 3 and 19 1 0 3 ma constrains the time elapsed between 430 450 c and 560 580 c which implies an average heating rate of 8 15 c m y combined with new fission track ages zircon 10 9 ma apatite 7 5 6 5 ma metamorphic rates of the entire orogenic cycle from prograde to final cooling can be reconstructed

variscan vs alpine tectonothermal evolution of the southern carpathian orogen constraints from 40ar 39ar ages abstract 40 ar 39 ar hornblende and muscovite ages indicate that basement units exposed within all major alpine nappes of the southern carpathian orogen were penetratively deformed and metamorphosed during late variscan carboniferous tectonothermal events subsequent exhumation resulted in cooling from ca 500 c hornblende k ar retention temperature to ca 375 c muscovite k ar retention temperature between ca 320 and 295 ma late variscan exhumation of middle crustal levels is interpreted to have resulted from intracontinental contraction and regional uplift subsequent to variscan continental collision between gondwana derived tectonic elements e g africa and laurussia muscovite ages within mylonite zones suggest that late variscan shear zones were probably associated with a regional shear system that developed along the southern margins of laurussia alpine metamorphic effects within the southern carpathians are generally nonpenetrative and are only significant within narrow zones of retrogression that are interpreted to have formed during initial attenuation of variscan crust associated with formation of the jurassic severin rift

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

oxygen and hydrogen isotope systematics of lake baikal siberia implications for paleoclimate studies we interpret oxygen and hydrogen isotope data for water samples from lake baikal siberia its tributaries and other local rivers and local precipitation in terms of the known water budget for the modern lake in order to gain insight into past limnological and climatic processes that influenced the lake lake baikal is remarkably uniform in its isotopic composition i80 15 8 0 2 0 6d 123 f 2 0 and lies slightly to the right of the global meteoric water line which suggests significant evaporation water is supplied to the lake by over 300 rivers and streams the oxygen isotope values 8180 of the rivers in the baikal catchment range from 13 4 to 21 2 0 the hydrogen isotope values sd for the same area range from 103 to 156 0 both these ranges generally conform to the global meteoric water line the weighted average isotopic composition of input to the lake rivers plus precipitation is 15 2 0 for 6 0 and 116 0 for 6d values higher than those of the modern lake therefore the isotopic composition of the modem lake cannot be related to the modern input through simple evaporation instead modeling of the isotopic mass balance of the lake suggests that inputs precipitation and influx from rivers and outputs evaporation and outflow are not at a steady state equilibrium under current climate conditions we found previous input to the lake had lower zy o and 6d values than modern input which reflects cooler climates in the past compared with modern conditions under constant climate conditions steady state conditions are not expected to be reached by the lake for at least 700 yr because of its large size and the long residence time of water in the lake

metamorphism graphite crystallinity and sulfide anatexis of the rampura agucha massive sulfide deposit northwestern india located adjacent to the banded gneissic complex rampura agucha is the only sulfide ore deposit discovered to date within the precambrian basement gneisses of rajasthan the massive zn pb sulfide orebody occurs within graphite biotite sillimanite schist along with garnet biotite sillimanite gneiss calc silicate gneisses amphibolites and garnet bearing leucosomes plagioclase hornblende thermometry in amphibolites yielded a peak metamorphic temperature of 720 780 c whereas temperatures obtained from fe mg exchange between garnet and biotite 580 610 c in the pelites correspond to postpeak resetting thermodynamic considerations of pertinent silicate equilibria coupled with sphalerite geobarometry furnished part of a clockwise p t t path with peak p t of 6 2 kbar and 780 c attained during granulite grade metamorphism of the major zn rich stratiform sedimentary exhalative deposits orebody and its host rocks arsenopyrite composition in the metamorphosed ore yielded a temperature and log f s2 range of 352 c 8 2 to 490 c 4 64 thus indicating its retrograde nature contrary to earlier research on the retrogressed nature of graphite raman spectroscopic studies on graphite in the metamorphosed ore reveal variable degree of preservation of prograde graphite crystals 490 43 c with a maximum at 593 c the main orebody is mineralogically simple sphalerite pyrite pyrrhotite arsenopyrite galena deformed and metamorphosed while the pb ag rich sulfosalt bearing veins and pods that are irregularly distributed within the hanging wall calc silicate gneisses show no evidence of deformation and metamorphism the sulfosalt minerals identified include freibergite boulangerite pyrargyrite stephanite diaphorite mn jamesonite cu free meneghinite and semseyite the last three are reported from agucha for the first time stability relations of cu free meneghinite and semseyite in the pb ag rich ores constrain temperatures at 550 c and 300 c respectively features such as 1 low galena sphalerite interfacial angles 2 presence of multiphase sulfide sulfosalt inclusions 3 microcracks filled with galena pyrargyrite without any hydrothermal alteration and 4 high contents of zn ag and sb in galena indicate partial melting in the pbs fe0 96s zns 1 ag2s cufes2 system which was critical for metamorphic remobilization of the rampura agucha deposit

raman spectra of carbonaceous material in metasediments a new geothermometer metasedimentary rocks generally contain carbonaceous material cm deriving from the evolution of organic matter originally present in the host sedimentary rock during metamorphic processes this organic matter is progressively transformed into graphite s s and the degree of organisation of cm is known as a reliable indicator of metamorphic grade in this study the degree of organisation of cm was systematically characterised by raman microspectroscopy across several mesozoic and cenozoic reference metamorphic belts this degree of organisation including within sample heterogeneity was quantified by the relative area of the defect band r2 ratio the results from the schistes lustres western alps and sanbagawa japan cross sections show that 1 even through simple visual inspection changes in the cm raman spectrum appear sensitive to variations of metamorphic grade 2 there is an excellent agreement between the r2 values calculated for the two sections when considering samples with an equivalent metamorphic grade and 3 the evolution of the r2 ratio with metamorphic grade is controlled by temperature t along the tinos cross section greece which is characterised by a strong gradient of greenschist facies overprint on eclogite facies rocks the r2 ratio is nearly constant consequently the degree of organisation of cm is not affected by the retrogression and records peak metamorphic conditions more generally analysis of 54 samples representative of high temperature low pressure to high pressure low temperature metamorphic gradients shows that there is a linear correlation between the r2 ratio and the peak temperature t c 445 r2 641 whatever the metamorphic gradient and probably the organic precursor the raman spectrum of cm can therefore be used as a geothermometer of the maximum temperature conditions reached during regional metamorphism temperature can be estimated to 50 c in the range 330 650 c a few technical indications are given for optimal application

gis based logistic regression for landslide susceptibility mapping of the zhongxian segment in the three gorges area china abstract a detailed landslide susceptibility map was produced using a logistic regression method with datasets developed for a geographic information system gis known as one of the most landslide prone areas in china the zhongxian shizhu segment in the three gorges reservoir region of china was selected as a suitable case to evaluate the frequency and distribution of landslides the site covered an area of 260 9 km 2 with a landslide area of 5 3 km 2 four data domains were used in this study remote sensing products thematic maps geological maps and topographical maps all with 25 25 m 2 pixels or cells statistical relationships for landslide susceptibility were developed using landslide and landslide causative factor databases we extended the application of logistic regression approaches to use all continuous variables as they are and the landslide density is used to transform these nominal variables to numeric variable according to the map 2 8 of the study area was identified as an area with very high susceptibility whereas very low low medium and high susceptibility zones covered 18 2 36 2 26 7 and 16 1 of the area respectively the quality of susceptibility mapping was validated and the correct classification percentage and root mean square error rmse values for the validation data were 81 4 and 0 392 respectively

statistical models for slope instability classification abstract statistical models for reliable hazard assessment of landslides in a given area are presented the models are based on information theory and regression analysis information theory is a branch of probability in which the most significant feature is unpredictability and regression analysis is based on simple statistical theory both methods of statistical prediction have been applied to slope instability to provide cross validation of the results a fortran 77 program for computer aided assessment of the landslide hazard has been developed the program considers the factors affecting the slope instability and history of past landslides of the area as its input the program also calculates the information and regression value in a given area and classifies the area into different grades of instability a case study of landslide hazard assessment of a 66 km2 area in parts of the alkananda valley the gharwal himalaya is presented the factors considered in the analysis are angle and height of the slope rock type and geological structures such as faults and thrusts the results obtained are illustrated in the form of landslide hazard maps the predicted results are compared by the above methods

gis techniques and statistical models in evaluating landslide hazard geographical information systems gis and numerical cartography may greatly facilitate the development and use of statistical models for the assessment of regional landslide hazard from a small drainage basin located in central italy relevant geological and geomorphological factors were collected and processed by applying gis technology in particular modules were used which both generate high fidelity digital terrain models and automatically partition the terrain into main slope units the resulting information was then analysed by discriminant analysis which enabled landslide hazard and risk to be evaluated in each slope unit although not lacking drawbacks the method proved to be a feasible and cost effective approach to landslide susceptibility assessment and mapping

bottomwater formation due to hydrothermal activity in frolikha bay lake baikal eastern siberia hydrothermal water enters frolikha bay a well known site of high geothermal heat flux in the northern part of lake baikal at 400 m depth on the basis of ctd profiles the hydrothermal water is identified as forming an anomalous bottom layer with a higher temperature 0 15 c and salinity 2 5 mg kg 1 than the overlying water due to the entrainment of lake water a distinct dense water layer up to 40 m thick stabilised by its slightly higher salinity becomes established close to the bottom of the bay the density current thus generated flows out of the bay towards the deeper parts of the basin since helium isotope analysis shows that the geochemical characteristics of the hydrothermal water are similar to those of water from nearby hot springs on land the bottomwater of frolikha bay is easily interpreted in terms of the mixing of ordinary fresh water from the lake and hydrothermal water carrying isotopically heavy he from the continental crust because of its high crustal he content a similar hydrothermal component may even be identified in the open water of the northern basin

artificial neural networks applied to landslide susceptibility assessment abstract landslide hazard mapping is often performed through the identification and analysis of hillslope instability factors usually managed as thematic data within geographic information systems gis in heuristic approaches these factors are rated by the attribution of scores based on the assumed role played by each of them in controlling the development of a sliding process other more refined methods based on the principle that the present and the past are keys to the future have also been developed thus allowing less subjective analyses in which landslide susceptibility is assessed by statistical relationships between past landslide events and hillslope instability factors the objective of this research is to define a method with the ability to forecast landslide susceptibility through the application of artificial neural networks anns the riomaggiore catchment a subwatershed of the reno river basin located in the northern apennines italy was chosen as an ideal test site as it is representative of many of the geomorphological settings within this region in the present application two different anns used in classification problems were set up and applied one belonging to the category of multi layered perceptron mlp and the other to the probabilistic neural network pnn family the hillslope factors that have been taken into account in the analysis were the following a lithology b slope angle c profile curvature d land cover and e upslope contributing area these factors have been classified on nominal scales and their intersection allowed 3342 homogeneous domains unique condition unit ucu to be singled out which correspond to the terrain units utilized in this analysis the model vector used to train the anns is a subset of that derived from the production of unique condition units and consists of 3342 records organized in input and output variable vectors in particular the hillslope factors once classified on nominal scales as binary numbers represent the 19 input variables while the presence absence of a landslide in a given terrain unit is assumed to be the output variable the comparison between the most up to date landslide inventory of the riomaggiore catchment and the hazardous areas as predicted by the anns showed satisfactory results with a slight preference for the mlp for this reason this is an encouraging preliminary approach towards a systematic introduction of ann based statistical methods in landslide hazard assessment and mapping

assessment of shallow landslide susceptibility by means of multivariate statistical techniques several multivariate statistical analyses have been performed to identify the most influential geological and geomorphological parameters on shallow landsliding and to quantify their relative contribution a data set was first prepared including more than 30 attributes of 230 failed and unfailed slopes the performance of principal component analysis t test and one way test allowed a preliminary selection of the most significant variables which were used as input variables for the discriminant analysis the function obtained has classified successfully 88 5 per cent of the overall slope population and 95 6 per cent of the failed slopes slope gradient watershed area and land use appeared as the most powerful discriminant factors a landslide susceptibility map based on the scores of the discriminant function has been prepared for ensija range in the eastern pyrenees an index of relative landslide density shows that the results of the map are consistent copyright 2001 john wiley sons ltd language en

carbonaceous material in pelitic schists of the sanbagawa metamorphic belt in central shikoku japan abstract carbonaceous material in pelitic schists of the sanbagawa metamorphic belt in central shikoku japan was separated from the host rocks and its x ray diffraction and chemical composition were studied its crystal structure and chemistry change continously with increasing metamorphic grade and approach those of well ordered graphite near the biotite isograd as graphitization is a rate process the temperature of complete graphitization differs from one metamorphic terrain to another as a function of the duration of metamorphism in an individual metamorphic terraan however the degree of graphitization is a useful indicator of relative metamorphic temperature in lower grade rocks

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

biogenic origin of intergrown mo sulphide and carbonaceous matter in lower cambrian black shales zunyi formation southern china abstract the lower cambrian zunyi formation in southern china hosts complex intergrown phases of mo sulphides and anthracite like carbonaceous matter and graphite mosc pyrite and ni sulphides these sulphides occur in a few centimeters thick polymetallic stratiform layer in black shales above phosphorites cherts dolomites and barite the ore horizon contains 7 wt mo 2 wt ni 19 wt s and 13 wt c org and c tot co 2 58 wt 14 wt cao 1 2 wt as 2000 ppm se 5400 ppm zn 450 ppm u and v and up to 1 ppm platinum group elements three types of mosc phases always including framboidal pyrite are distinguished 1 rounded structures few hundred microns large 2 relict inclusions in diagenetic pyrite 3 grains interstitial to sulphurised and phosphatised organic matter at the nanoscale mosc is represented by nanometric porous rounded structures of mos 2 finely intergrown with carbonaceous matter of typical nano onion structures mosc also contains nanocrysts of quartz clays ca sulphate carbonate and ni sulphides micro raman spectroscopy shows that the carbon phase has a maturation grade of anthracite indicating temperatures below 300 c mosc is mainly composed of 25 wt mo 23 wt s 5 6 wt fe 2 5 wt ni 33 wt c 1 5 wt o 0 6 wt n and several hundreds of ppm of cu as se sb pd zn co and sn electron energy loss spectra show that n is related to nanosized carbonaceous matter the mean c n ratio 57 of mosc is similar to those observed in marine organic matter and those reported from zooplankton at hydrothermal vents the mineralized shales are crosscut by hydrothermal veins composed of carbonate or barite always associated with quartz apatite and fe and zn sulphides a paragenesis also observed as nanocrysts in mosc although mo originated from seawater its extreme concentration is due to an enhanced growth of bacterial consortia in a diffuse hydrothermal vent system these consortia may be dominated by nitrogen fixing and mo dependant hyperthermophilic or mesophilic species containing nitrogenase composed also of mo s fe organic matter decay led thus to the formation of mosc and the included framboidal pyrite

susceptibility zoning of shallow landslides in fine grained soils by statistical methods abstract the paper proposes a methodology in two successive steps to zone the susceptibility to shallow landslides in fine grained soils by means of statistical methods the first step of the methodology aiming at defining calibrating and validating the statistical analysis ends with a landslide susceptibility computational map the second step of the methodology is employed to produce a susceptibility map for zoning purposes this structured methodology arises from the need to distinguish at any given scale of analysis between the spatial discretization needed to perform the statistical computations terrain computational units and terrain units useful for zoning purposes terrain zoning units the applicability of the proposed methodology is tested at two different scales 1 25 000 and 1 5000 in two areas of southern italy the test area for the larger scale being a portion of the test area used for the analysis at the smaller scale this allows for the generalization of the obtained results through the comparison for the same phenomena in the same geo environmental context of the predisposing factors at two scales of analysis in both analyses the relevant variables for the susceptibility assessment are elevation zone slope gradient slope curvature and geology in the analysis at large scale also the weathered rock thickness available only at this scale assumes a relevant role in both cases the aggregation of multiple terrain computational units tcu into a larger terrain zoning unit tzu works best when focal statistic techniques are used with a characteristic dimension of the area of influence equal to 16 tcus

geomorphological and historical data in assessing landslide hazard traditionally earth scientists assess landslide occurrence on the basis of geomorphological investigations carried out through aerial photograph interpretation and eldwork conversely local administrators primarily evaluate the impact of natural catastrophes such as landsliding on the basis of historical records and data owing to the substantial difference in the structure and spatial density of these two types of information it is dif cult to compare them directly and few investigators have attempted this we compared landslide information derived from geomorphological mapping and historical data in a pilot area the staffora river basin northern italy to do this we generated two multivariate statistical models where the dependent variable was either the mapped landslide deposits geomorphological model or the historical sites affected by landslide induced damage historical model by quantitatively comparing these two model maps we demonstrate that the geomorphological model performs better in terms of percentage of terrain units correctly predicted as stable or unstable the historical model underestimates landslide hazard mainly where human structures are lacking however it highlights slopes where landslide movements take place with a high frequency at the temporal scale of human life hence the joint use of these two models may facilitate the knowledge of the overall instability conditions of a given region and the identi cation of the landslides that are most frequently reactivated copyright 2003 john wiley sons ltd

cretaceous to miocene thrusting and wrenching along the central south carpathians due to a corner effect during collision and orocline formation field studies in the romanian south carpathians longitude 22 5 to 24 2 e and latitude 45 2 to 45 6 n demonstrate 1 cretaceous top to ne shearing parallel to the present strike of the thrust system connected with coaxial flattening within the generally northwest dipping foliation 2 paleogene ductile brittle dextral wrenching e w compression 1 87 15 and basin formation petrosani basin along the cerna jiu fault system 3 large scale miocene dextral wrenching along the northern margin of moesia 1 143 16 and 4 probably pliocene early pleistocene n s compression 1 205 25 we discuss the tectonics of the south carpathians stressing the corner effect of the moesian foreland promontory during convergence and formation of the carpathian orocline up to the late early cretaceous subduction of oceanic crust was active between europe moesia on one side and east carpathia rhodopia on the other side collision and intracontinental deformation occurred during the late early and late cretaceous the pinning of the thrust front at the western tip of moesia and the foreland recess north of it caused superposition of thrusting and wrenching during collision and lateral translation tangential stretching during orocline formation and spreading into the recess further convergence during the early tertiary resulted in dislocation of the previously welded east carpathian rhodopian and moesian fragments along the cerna jiu fault system and the further northeast translation of the western segment the intramontane petrosani basin opened as a northeasterly propagating transient pull apart structure along the cerna jiu fault system which acquired a curved northwesterly convex transtensional trace due to the shape of the moesian promontory tightening of the carpathian orocline and or rearrangement of the microplate geometry during the formation of the pannonian basin system led to large scale dextral wrenching along the northern margin of moesia pliocene n s compression reflects final shortening in the carpathian system before ongoing convergence between europe and africa was transferred to the mediterranean rotation of material lines around the moesian corner is corroborated by paleomagnetic studies

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

significance of graphite occurrences in the aracena metamorphic belt iberian massif the significance of syngenetic and epigenetic graphite occurrences from the variscan high temperature low pressure aracena metamorphic belt is discussed in the framework of the tectono thermal evolution of this southern zone of the iberian massif syngenetic graphite is associated with both low to medium grade metamorphic rocks la umbria series precambrian in age and high grade granulite facies rocks the precambrian fuente del oro series and a cambrian calc silicate series epigenetic fluid deposited occurrences correspond to overgrowths on existing metamorphic graphite grains and vein type mineralization two types of graphitized particles with remarkable differences in reflectance anisotropy and size can be distinguished in the precambrian metapelites of the la umbria series large 150 m length platy crystals with high reflectance and anisotropy are interpreted as detrital and are considered indirect evidence of an old orogenic cycle prior to the cadomian orogeny during which metamorphism exceeded greenschist facies the coexistence of two types of particles explains the scattering of values of the c parameter of graphite determined by xrd c 6 72 6 74 a and the anomalously high temperatures of the dta exothermic peak close to 600 c of graphite with respect to that inferred from mineral assemblages in these rocks the presence of graphite rich quartzites and gneisses within the fuente del oro series and the calc silicate series is evidence of sedimentation under reducing conditions in a continental shelf the characteristics of graphite reflect the high grade metamorphic conditions attained in the southern area of the aracena metamorphic belt pervasive flow of fluids related to a major variscan extensional event resulted in overgrowths on the pre existing graphite in the gneisses and quartzites of the calc silicate series as evidenced by the heterogeneous isotopic composition of graphite single crystals in these rocks a later stage of graphite precipitation is represented by scarce vein type occurrences in mafic granulites that document channelled flow of fluids

siliceous sublacustrine spring deposits around hydrothermal vents in lake taupo new zealand chimneys around hydrothermal vents at a depth of c 140 m in the horomatangi reefs area in lake taupo new zealand are composed of amorphous silica opal a with lesser amounts of mn fe and hg rich precipitates detrital quartz and feldspar grains are found in the surrounding sediments the associated biota includes fish bacteria sponges crayfish amphipods copepods ostracodes annelids and other unidentified organisms much of this biota however is not preserved in the opal a deposits instead the silicified biota includes filamentous microbes and diatoms scattered coccoid microbes fungal hyphae and spores rare sponge spicules and rare worm tubes the diatoms coccoid microbes and fungi were brought into the area with the detrital sediment in ancient successions distinction between sublacustrine terrestrial and some marine hot spring deposits may be difficult because the precipitates share many similarities distinction based on the biota is viable only if palaeoecological information can be inferred from accurately identified organisms unfortunately silicification commonly disguises microbes and precludes their accurate identification diagenetic transformation of opal a to its more stable polymorphs also destroys many original depositional fabrics and silicified microbes distinction between the different types of spring deposit may therefore depend on the interpretation of their overall sedimentological and stratigraphic setting

a new old approach for shallow landslide analysis and susceptibility zoning in fine grained weathered soils of southern italy abstract rainfall induced shallow landslides involve several geo environmental contexts and different types of soils in clayey soils they affect the most superficial layer which is generally constituted by physically weathered soils characterised by a diffuse pattern of cracks this type of landslide most commonly occurs in the form of multiple occurrence landslide phenomena simultaneously involving large areas and thus has several consequences in terms of environmental and economic damage indeed landslide susceptibility zoning is a relevant issue for land use planning and or design purposes this study proposes a multi scale approach to reach this goal the proposed approach is tested and validated over an area in southern italy affected by widespread shallow landslides that can be classified as earth slides and earth slide flows specifically by moving from a small 1 100 000 to a medium scale 1 25 000 with the aid of heuristic and statistical methods the approach identifies the main factors leading to landslide occurrence and effectively detects the areas potentially affected by these phenomena finally at a larger scale 1 5000 deterministic methods i e physically based models trigrs and trigrs unsaturated allow quantitative landslide susceptibility assessment starting from sample areas representative of those that can be affected by shallow landslides considering the reliability of the obtained results the proposed approach seems useful for analysing other case studies in similar geological contexts

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

a new technique for recognition of geological and geomorphological patterns in digital terrain models abstract we have developed a technique that recognizes monoclinal sedimentary strata showing strike ridge geomorphology and fluvial deposits from digital terrain models dtms this technique is efficient and reliable and may be expanded to analysis of other landforms techniques for rapid geomorphic analysis of dtms are becoming increasingly useful since digital stereoscopic spot data will soon be available worldwide our technique recognizes geomorphic elements in two steps first elementary objects including crests thalwegs and various slope types are classified from slope changes along n s e w nw se and ne sw profiles through pixels in the dtm image second grammatical pattern recognition is used to identify and map geomorphic forms from the succession of elementary objects

multiscale characterization of pyritized plant tissues in blueschist facies metamorphic rocks pyritized plant tissues with well preserved morphology were studied in rocks from vanoise western alps france that experienced high pressure low temperature metamorphic conditions in the blueschist facies during the alpine orogeny organic and inorganic phases composing these fossils were characterized down to the nanometer scale by raman microspectroscopy scanning transmission x ray microscopy and transmission electron microscopy the graphitic but disordered organic matter composing these fossils is chemically and structurally homogeneous and mostly contains aromatic functional groups its original chemistry remains undefined likely because it was significantly transformed by diagenetic processes and or thermal degradation during metamorphism various mineral phases are closely associated with this organic matter including sulphides such as pyrite and pyrrhotite carbonates such as ankerite and calcite and iron oxides a tentative time sequence of formation of these diverse mineral phases relative to organic matter decay is proposed the absence of traces of organic matter sulphurization the pervasive pyritization of the vascular tissues and the presence of ankerite suggest that the depositional diagenetic environment of these metasediments was likely rich in reactive iron fe sulphides and ankerite likely precipitated early and might have promoted the preservation of the fossilized biological soft tissues by providing mechanical resistance to compaction during diagenesis and subsequent metamorphism in contrast iron oxides which form rims of 100 nm in thickness at the interface between organic matter and fe sulphides may result from metamorphic processes this study illustrates that it may be possible in some instances to deconvolve metamorphic from diagenetic imprints and opens new avenues to better constrain processes that may allow the preservation of organic fossils during diagenesis and metamorphism

fluid rich damage zone of an ancient out of sequence thrust kodiak islands alaska 1 the uganik thrust is a fossil out of sequence thrust fault which was active over a period of 3 ma during the early tertiary until activity ceased with the subduction of the kula farallon spreading ridge at 57 ma during this period the fault experienced at least 1 km of throw and developed a strongly asymmetric damage zone the brittle damage zone in the footwall of the fault acted as a conduit for fluid advection during the active faulting a similar asymmetrical footwall damage zone has been interpreted as a fluid conduit at the nobeoka thrust shimanto belt sw japan thermal indicators in the uppermost footwall give similar maximum paleotemperatures to those in the hanging wall 280 c while previous work elsewhere in the footwall formation suggests maximum burial temperatures of 240 c in this case similar to the irish canyon thrust in the franciscan accretionary complex the location of the thermal anomaly is spatially offset from the structural fault which caused it owing to thermal overprinting in the vicinity of the fault

the kumaun and garwhal lesser himalaya india part 2 thermal and deformation histories an integrated petrologic thermochronologic and numerical modeling study constrains the thermal evolution of the lesser himalayan sequence in the kumaun and garwhal regions of india south of the tons thrust peak metamorphic temperatures do not exceed 330 c on the northern side a transition toward higher temperatures adjacent to the main central thrust hanging wall is documented in the immediate footwall of the main central thrust peak temperatures average 550 c an inverted thermal field gradient of 30 c km beneath the vaikrita thrust is calculated an inverted thermal field gradient of 20 c km is also documented beneath a klippe of the main central thrust hanging wall 25 km south of the vaikrita thrust and a peak footwall temperature of 530 c is recorded close to the shear zone at the base of the klippe the mechanism for thermal metamorphism in the lesser himalayan sequence is interpreted to be conduction of heat from the main central thrust fault and or hanging wall to the footwall a localized thermal field gradient is also associated with the tons thrust the 40 ar 39 ar thermochronology reveals that the exposed rock in the kumaun and garwhal lesser himalaya underwent cooling below the closure temperature tc for white mica at different times in the late tertiary the proximal footwall of the munsiari thrust experienced cooling below the white mica tc at ca 8 5 ma south of the munsiari thrust in the proximal footwalls of the chaukori and askot klippen muscovites ages are ca 11 5 ma 3 ma older than samples to the north the age differences in samples from northern and southern exposures are interpreted to document cooling related to thermal relaxation following passage of the main central thrust hanging wall atop the lesser himalayan sequence results of thermal modeling achieve good fits to the data when scenarios involve an early miocene phase of overthrusting of a hot hanging wall over a downgoing footwall followed by the initiation of a duplex within lesser himalayan sequence rocks

the neoproterozoic pan african basement from the alpine lower danubian nappe system south carpathians romania abstract the south carpathians which were thrust to the moesian platform in the alpine orogeny late cretaceous to tertiary include the danubian nappe system the danubian pre alpine basement comprises two variscan nappes each one made up of partially retrogressed amphibolite facies rocks intruded by granitoids and capped by an ordovician devonian volcano sedimentary cover no lithological correlation can be established between the pre ordovician basements of these two units the metamorphic basement from the first variscan nappe the dr gsan group is composed of banded amphibolites with some augen and aluminous gneisses intruded by granodioritic to tonalitic plutons the banded structure of the amphibolites together with their geochemistry suggests a volcano sedimentary sequence zircon u pb data on an intercalated augen gneiss have given an age of 777 3 ma for the emplacement of the protolith of this gneiss nd model ages t dm for the amphibolites range from 717 ma to 817 ma at 777 ma nd values cluster is at 8 3 to 9 8 and sr initial ratios range between 0 7007 and 0 7023 indicating an oceanic origin without continental crust contamination major and trace elements from the dr gsan amphibolites consistently display an island arc signature with three differentiation trends evolving from an early tholeiitic trend to a more differentiated low k calc alkaline one the dr gsan terrane is similar to the early pan african juvenile terranes of the sahara the basement of the second variscan nappe the lainici p ius group is made up of metasedimentary rocks mainly quartzites marbles and graphitic mica gneisses cut by early leucogranitic dykes medium k calc alkaline and alkali calcic mainly granitic plutons and late medium k porphyry diorite dykes this magmatism can be bracketed between 588 ma and 567 ma u pb zircon ages the best preserved pluton tismana 567 ma old displays a composite alkali calcic very high k calc alkaline magmatic sequence ranging from gabbro diorite to monzogranite including an ultramafic pod ages and geochemical signatures resemble the saharan late pan african granitoids the existence of late precambrian partly juvenile terrains is thus confirmed within the basement of south carpathians which renders then a segment of the european alpine belt that can be successfully compared to the pan african trans saharan belt

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

structural and thermal characters of the longmen shan sichuan china article i nfo the longmen shan sichuan china is characterised by an unusual morphology which results from a triassic prism tectonics and a more recent neogene thick skin thrusting among its specific features isthe high elevation of the internal zones incontinuity with the songpan garze fold and thrust belt sg which is associated with an abrupt 20 km moho offset between the sichuan basin and the tibetan plateau as revealed by the analysis of teleseismic data acquired by a dense seismic network the jump in crustal thickness is located at the apex of the wenchuan shear zone wsz and marks the western boundary of the metamorphosed units of sg characterized by temperatures varying from 590 c down to 300 c as commonly observed in mature accretionary wedges both the structural style marked by intense shortening in tight kink folds and geophysical data suggest the presence of an horizontal discontinuity at 15 km depth over a thick crust 63 km the longmen shan east of the wsz is characterized by thick skin detachment which thrusts the internal sedimentary unitsandtheproterozoicbasementoverthe seriesof thesichuanbasindepositedona thinnercrust of 44 km thick the majorfront isthebeichuanfault zone bfz which broughtthe internalzones onto triassic and jurassic series with lower temperatures less than 400 c locally temperatures of 425 c are found just below the klippes these results are in agreement with an original contact of the sg zone represented by an accretionary wedge of sediments thrusted over the margin of the continental crust of the yangtze craton in the early stage indosinian of the evolution the present day slow e w component of the convergence added to the difference in crustal thickness caused the yangtze crust to indent the songpan tibetan crust which was softened by a high thermal regime asaresponsetheedgeofthetibetcrustwasinflatedtothebottom upto70 km whereastothetop the crystalline massif were exhumed and pushed the deformation eastward as emerging and blind thrusts this configuration reflects a moderate shortening of the crust which behaves as a soft thick material abutting the

relationships between tectonic and geomorphological linear features in the guadix baza basin southern spain linear elements of the landscape of the guadix baza basin southern spain were identified from a landsat tm image three important lineament trends have been identified in the guadix baza basin the first is ne sw which is the dominant trend in the basin the second is nw se and the third is ene wsw these three trends are correlated to the major faults of the guadix baza basin the study of linear features by the analysis of satellite data has revealed a strong link between the buried tectonic structures and the morphological features appearing at the surface the distribution and density of lineaments explains much of the morphology of the land surface it is possible to reconstruct elements of the tectonic and denudational history of the region and show that during quaternary times lineaments controlled the sedimentation of the basin and the drainage pattern copyright 1999 john wiley sons ltd

combining spatial data in landslide reactivation susceptibility mapping a likelihood ratio based approach in w belgium a key issue in landslide susceptibility mapping concerns the relevance of the spatial data combination used in the prediction various combinations of high resolution predictor variables and possibilities of selecting them from a larger dataset are analysed the scarp reactivation of several landslides in a hilly region of w belgium is investigated at the pixel scale the susceptibility modelling uses the reactivated scarp segments as the dependent variable and 13 factors at a 2 m resolution related to topography hydrology land use and lithology as potential independent variables the modelling uses a likelihood ratio approach based on the comparison for each independent variable between two empirical distribution functions edfs respectively for the reactivated and non reactivated areas it uses these edfs as favourability values to build membership values and combine them with a fuzzy gamma operator five different data combinations are tested and compared by analysing the prediction rate curves obtained by cross validation the geomorphological value of the resulting susceptibility maps is also discussed this research shows relevant results for predicting the susceptibility to scarp reactivation we highlight the need for testing several data combinations and underline that combining quantitative criteria with expert opinion is an asset for reliable predictions

probabilistic landslide hazard assessment at the basin scale abstract we propose a probabilistic model to determine landslide hazard at the basin scale the model predicts where landslides will occur how frequently they will occur and how large they will be we test the model in the staffora river basin in the northern apennines italy for the study area we prepare a multi temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999 we partition the basin into 2243 geo morpho hydrological units and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables including morphological lithological structural and land use for each mapping unit we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period assuming that landslide recurrence will remain the same in the future and adopting a poisson probability model we determine the exceedance probability of having one or more landslides in each mapping unit for different periods we obtain the probability of landslide size by analysing the frequency area statistics of landslides obtained from the multi temporal inventory map assuming independence we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size of landslide temporal occurrence and of landslide spatial occurrence

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

a chlorite solid solution geothermometer the los azufres mexico geothermal system chlorite constitutes a major hydrothermal alteration product of metamorphism of andesites in the active geothermal system of los azufres mexico electron microprobe analyses performed on a set of crystals from each sample show wide variations in composition correlation coefficients among chemical constituents were calculated it is shown that the tetrahedral charge is positively correlated with the octahedral vacancy and negatively with the iron content and there is almost no correlation with the octahedral aluminium and magnesium content a procedure is proposed to select end members and substitution vectors and to give a general formula for these chlorites

assessment of landslide susceptibility on the natural terrain of lantau island hong kong steep terrain and the high frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong for example more than 800 slope failures were triggered by a rainstorm in november 1993 on lantau island hong kong maps of recent landslides interpreted from aerial photographs in combination with a geographical information system were used to evaluate the frequency and distribution of landslides with particular reference to such physical parameters as lithology slope gradient slope aspect elevation vegetation cover and proximity to drainage line all of which are considered to be influential in the occurrence of landslides a stepwise logistic regression model was obtained between landslide susceptibility and the above mentioned physical parameters the study area has been classified into five classes of relative landslide susceptibility namely very low low moderate high and very high based on this methodology

a comparison of statistical and deterministic methods for shallow landslide susceptibility zoning in clayey soils abstract shallow landslides are widespread in different geological contexts and generally occur as multiple events over large areas when these phenomena involve fine grained soils they may cause serious consequences in terms of environmental and property damages and thus their spatial forecasting becomes a relevant issue for land use planning and design purposes the existing literature provides several methods for landslide susceptibility assessment categorized in qualitative and quantitative methods when dealing with analyses at large scale 1 5000 quantitative methods are generally preferred in this paper landslide susceptibility maps are produced for a study area prone to shallow landsliding located in catanzaro southern italy to this aim two quantitative methods are implemented the statistical information value method and the deterministic trigrs model the two approaches are compared by means of two indicators of the grade of correctness of the landslide susceptibility maps the area under curve of the roc curve auc and the overestimation index oi the results of the analyses in terms of auc values demonstrate the effectiveness and consistency of both methods in performing the susceptibility mapping of the study area when the oi values are considered the results provided by the deterministic model are slightly better than the ones resulting from the statistical analysis this does not come as a surprise for the case study at hand and it can be ascribed to the availability within the study area of a reliable database of soil properties and an in depth knowledge of the behaviour of the considered landslides

a spatiotemporal probabilistic modelling of storm induced shallow landsliding using aerial photographs and logistic regression landslides constitute one of the major natural hazards that could cause significant losses of life and property mapping or delineating areas prone to landsliding is therefore essential for land use activities and management decision making in hilly or mountainous regions a landslide hazard map can be constructed by a qualitative combination of maps of site conditions including geology topography and geomorphology by statistical methods through correlating landslide occurrence with geologic and geomorphic factors or by using safety factors from stability analysis a landslide hazard map should provide information on both the spatial and temporal probabilities of landsliding in a certain area however most previous studies have focused on susceptibility mapping rather than on hazard mapping in a spatiotemporal context this study aims at developing a predictive model based on both quasi static and dynamic variables to determine the probability of landsliding in terms of space and time the study area selected is about 13 km 2 in north lantau hong kong the source areas of the landslides caused by the rainstorms of 18 july 1992 and 4 5 november 1993 were interpreted from multi temporal aerial photographs landslide data lithology digital elevation model data land cover and rainfall data were digitized into a geographic information system database a logistic regression model was developed using lithology slope gradient slope aspect elevation slope shape land cover and rolling 24 it rainfall as independent variables since the dependent variable could be expressed in a dichotomous way this model achieved an overall accuracy of 87 2 with 89 5 of landslide grid cells correctly classified and found to be performing satisfactorily the model was then applied to rainfalls of a variety of periods of return to predict the probability of landsliding on natural slopes in space and time it is observed that the modelling techniques described here are useful for predicting the spatiotemporal probability of landsliding and can be used by land use planners to develop effective management strategies copyright 0 2003 john wiley sons ltd

prediction of landslide susceptibility using rare events logistic regression a case study in the flemish ardennes belgium abstract in this article a statistical multivariate method i e rare events logistic regression is evaluated for the creation of a landslide susceptibility map in a 200 km2 study area of the flemish ardennes belgium the methodology is based on the hypothesis that future landslides will have the same causal factors as the landslides initiated in the past the information on the past landslides comes from a landslide inventory map obtained by detailed field surveys and by the analysis of lidar light detection and ranging derived hillshade maps information on the causal factors e g slope gradient aspect lithology and soil drainage was extracted from digital elevation models derived from lidar and from topographical lithological and soil maps in landslide affected areas however we did not use the present day hillslope gradient in order to reflect the hillslope condition prior to landsliding the pre landslide hillslope was reconstructed and its gradient was used in the analysis because of their limited spatial occurrence the landslides in the study area can be regarded as rare events rare events logistic regression differs from ordinary logistic regression because it takes into account the low proportion of 1s landslides to 0s no landslides in the study area by incorporating three correction measures the endogenous stratified sampling of the dataset the prior correction of the intercept and the correction of the probabilities to include the estimation uncertainty for the study area significant model results were obtained with pre landslide hillslope gradient and three different clayey lithologies being important predictor variables receiver operating characteristic roc curves and the kappa index were used to validate the model both show a good agreement between the observed and predicted values of the validation dataset based on a qualified judgement the created landslide susceptibility map was classified into four classes i e very high high moderate and low susceptibility if interpreted correctly this classified susceptibility map is an important tool for the delineation of zones where prevention measures are needed and human interference should be limited in order to avoid property damage due to landslides

alpine polyphase tectono metamorphic evolution of the south carpathians a new overview abstract the main terrains involved in the cretaceous tertiary tectonism in the south carpathians segment of the european alpine orogen are the getic supragetic and danubian continental crust fragments separated by the severin oceanic crust floored basin during the early middle cretaceous times the danubian microplate acted initially as a foreland unit strongly involved in the south carpathians nappe stacking multistage folding thrusting events uplift erosion and extensional stages and the development of associated sedimentary basins characterize the south carpathians during cretaceous to tertiary convergence and collision events the main cretaceous tectogenetic events responsible for contraction and crustal thickening processes in the south carpathians are mid cretaceous austrian phase and latest cretaceous laramide or getic phase in age the architecture of the south carpathians suggests polyphase tectonic evolution and mountain building and includes from top to bottom the getic supragetic basement cover nappes the severin and arjana cover nappes and danubian basement cover nappes all tectonically overriding the moesian platform the severin nappe complex including obarsia and severin nappes with late jurassic early cretaceous ophiolites and turbidites is squeezed between the danubian and getic supragetic basement nappes as a result of successive thrusting of dismembered units during the inferred mid to late cretaceous subduction collision followed by tectonic inversion processes early cretaceous thick skinned tectonics was replaced by thin skinned tectonics in late cretaceous thus the former middle cretaceous austrian nappe stack and its albian lower senonian cover got incorporated in the intra senonian laramide getic stacking of the getic supragetic severin arjana nappes onto the danubian nappe duplex the two contraction events are separated by an extensional tectonic phase in the upper plate recorded by the intrusion of the banatitic magmas 84 73 ma the overthrusting of the entire south carpathian cretaceous nappe stack onto the fold thrust foredeep units and to the moesian platform took place in the late miocene intra sarmatian times and was followed by extensional events and sedimentary basin formation

sublacustrine mud volcanoes and methane seeps caused by dissociation of gas hydrates in lake baikal four lake floor seeps have been studied in the gas hydrate area in lake baikal s south basin by using side scan sonar detailed bathymetry measurements of near bottom water properties heat flow measurements and selected seismic profiles in relation to results from geochemical pore water analysis the seeps at the lake floor are identified as methane seeps and occur in an area of high heat flow where the base of the gas hydrate layer shallows rapidly toward the vent sites from 400 m to 150 m below the lake floor at the site of the seep a vertical fluid conduit disrupts the sedimentary stratification from the base of the hydrate layer to the lake floor the seeps are interpreted to result from local destabilization of gas hydrate caused by a pulse of hydrothermal fluid flow along an active fault segment this is the first time that methane seeps and or mud volcanoes as sociated with gas hydrate destabilization have been observed in a sublacustrine setting the finding demonstrates the potential of tectonically controlled gas hydrate destabiliza tion to cause extreme pore fluid overpressure and short lived mud volcanism

thermal metamorphism in the lesser himalaya of nepal determined from raman spectroscopy of carbonaceous material the determination of metamorphic conditions is critical to the understanding of the formation of mountain belts however all collisional mountain belts contain large volumes of accreted sediments generally lacking metamorphic index minerals and are therefore not amenable to conventional petrologic investigations by contrast these units are often rich in carbonaceous material making it possible to determine thermal metamorphism through raman spectroscopy of carbonaceous material rscm method a technique that has been recently calibrated beyssac et al j metamorph geol 20 2002 859 871 the lesser himalaya lh is one of these problematic cases with a very poor mineralogy but a key structural position within the himalayan system that makes lh considered as diagnostic of the overall thermal behaviour of the orogen this work demonstrates the performance of the rscm technique and shows that this technique might thus be used to detect inter sample variations as small as 10 15 c but absolute temperatures can only be determined to 50 c due to the uncertainty on the calibration this study reveals that the lh has undergone a large scale thermal metamorphism with temperature decreasing progressively from about 540 c at the top to less than 330 c within the deepest exhumed structural levels

carbon ordering in an aseismic shear zone implications for raman geothermometry and strain tracking abstract determining the burial and strain history of sedimentary rocks is important for understanding crustal behaviour when rocks contain organic carbon increased temperatures at depth can alter the molecular structure of the carbon this change known as carbon ordering can be detected using raman spectroscopy as a result raman spectroscopy is increasingly used to estimate burial depths and associated maximum temperatures in carbon bearing rocks it is known from experiments and natural samples that other factors can affect raman derived maximum temperatures including frictional heating on fault planes and interaction with hot fluids for faulted samples a question remains as to whether it is purely frictional heating that causes carbon ordering or strain or a combination of the two in this study we use a mid crustal shear zone to show that strain related carbon ordering occurs in natural rock samples during aseismic shear strain a traverse across the shear zone whose relative strain we quantify with respect to the surrounding less deformed rock shows a marked decrease in raman d g peak intensity ratios indicating greater carbon ordering within the shear zone we interpret this as evidence for carbon ordering as a result of aseismic shear strain rather than inflated temperatures due to frictional heating commonly associated with seismic strain rates on faults our results have implications for the further development of raman spectroscopy as a geothermometer which may yield erroneous results in strained rock samples and for understanding strain localisation processes in the earth s crust and its associated rheological implications

artificial neural networks and cluster analysis in landslide susceptibility zonation a landslide susceptibility analysis is performed by means of artificial neural network ann and cluster analysis ca this kind of analysis is aimed at using anns to model the complex non linear relationships between mass movements and conditioning factors for susceptibility zonation in order to identify unstable areas the proposed method adopts ca to improve the selection of training validation and test records from data managed within a geographic information system gis in particular we introduce a domain specific distance measure in cluster formation clustering is used in data pre processing to select non landslide records and is performed on the whole dataset excluding the test set landslides susceptibility analysis is carried out by means of anns on the so generated data and compared with the common strategy to select random non landslide samples from pixels without landslides the proposed method has been applied in the brembilla municipality a landslide prone area in the southern alps italy the results show significant differences between the two sampling methods the classification of the test set previously separated and excluded from the training data is always better when the non landslide patterns are obtained using the proposed cluster sampling the case study validates that by means of a domain specific distance measure in cluster formation it is possible to introduce expert knowledge into the black box modelling method implemented by anns to improve the predictive capability and the robustness of the models obtained

detrital graphite particles in the cryogenian nantuo formation of south china implications for sedimentary provenance and tectonic history abstract the tectonic history of the yangtze block of south china prior to the ediacaran period has been a matter of debate in particular the tectonic history of the shennongjia terrane in the central northern margin of the yangtze block is poorly understood and the tectonic relationship between the shennongjia terrane and the huangling massif exposed in the huangling anticline is unclear previous researchers have reported u pb dates of detrital zircons and nd isotopic compositions of clastic rocks from cryogenian successions in the shennongjia terrane to identify ancient crustal remnants and the provenance of clastic sediments and to constrain the age and crustal evolution of the yangtze block here we describe abundant graphite discs from silty mudstone of the cryogenian nantuo formation in the shennongjia area of the yangtze block these graphite discs are opaque 23 171 m in size and highly reflective most are abraded or rounded although some show hexagonal crystalline morphology their raman spectra are distinct from those of indigenous carbonaceous material cm in the sedimentary matrix from the nantuo formation at the same locality raman cm geothermometric analysis indicates that graphite discs experienced a maximum metamorphic temperature of nearly 600 c which is inconsistent with the relatively low metamorphic grade of the host rock these observations indicate that the graphite discs are of detrital origin most likely derived from high grade metamorphic rocks in the basement of the yangtze block e g the archean paleoproterozoic kongling terrain in the core of the huangling anticline consistent with the hypothesis that the shennongjia region was a part of yangtze block by the end of the cryogenian period

metamorphic evolution of a very low to low grade metamorphic core complex danubian window in the south carpathians the danubian window characterized by diagenetic to low greenschist facies conditions at a high thermal gradient is evidently of great interest for methodological studies because high metamorphic thermal gradient conditions during low grade metamorphism have received little attention so far the general increase in metamorphic grade from sw to ne in the danubian window is indicated by mineral parageneses studies as well as by illite kubler index ki measurements and organic matter reflectance omr for the first time this study distinguishes between metamorphic conditions related to jurassic ocean floor cretaceous nappe stacking post collisional accommodation and syn kinematic getic detachment metamorphism and cooling after oligocene exhumation the occurrence of the prehnite pumpellyite facies in the severin cosustea units in the southeastern area is the result of cretaceous metamorphism remnants of ocean floor metamorphism prevailed the highest pressure is constrained by the upper stability limit of prehnite to be at around 4 0 kbar the danubian units situated within the diagenetic zone were not below 200 8c due to epidote formation the ki omr and mineral data indicate diagenetic conditions assuming temperatures between 200 and 250 8c pressures between 1 8 and 2 6 kbar were calculated using kinetic and numerical maturity models orogenic collisional cretaceous peak pressure conditions of 4 0 1 0 kbar are found in the danubian nappes not altered by a subsequent syn detachment metamorphic overprint highest temperatures in chloritoid schists and epidote hornblende bearing mylonites have been inferred for samples from the northern border of the danubian window between 300 and 400 8c along a synto post detachment retrograde pressure path post dating the chloritoid formation the occurrence of clinozoisite chlorite quartz suggests temperatures 300 8c in the northwest while the association andalusite quartz and biotite muscovite indicates temperatures between 370 and 400 8c at 3 5 kbar in the northeast it is demonstrated that the slope of the regression lines between ki and omr data gives valuable qualitative information about the relative magnitudes of p and t the slope of the regression line for the danubian window samples indicates normal heat flow conditions during nappe stacking and hyperthermal conditions during the formation of the getic detachment high thermal gradient conditions can easily be explained by partly isothermal decompression during the getic detachment event the elevation of the geotherm being caused by crustal thinning and rapid exhumation of the danubian units probably also a higher heat flux prevailed at the end of the getic detachment at a time when the retrograde chloritoid decomposition reactions took place documenting late stage ht greenschist facies metamorphism from siegesmund s fugenschuh b froitzheim n eds tectonic aspects of the alpine dinaridecarpathian system geological society london special publications 298 281 315 doi 10 1144 sp298 14 0305 8719 08 15 00 the geological society of london 2008 location of the study area and

ordovician continental margin terranes in the lachlan orogen australia implications for tectonics in an accretionary orogen along the east gondwana margin 1 four continental margin turbidite black shale terranes of the lachlan orogen in the southern tasmanides of eastern australia formed in two major systems along the east gondwana margin and constrain the ordovician assembly of this accretionary orogen key features are the dissimilar stratigraphies of the adjacent bendigo and melbourne terranes in the western system the dissimilar stratigraphies of the adjacent melbourne and albury bega terranes that reflect juxtaposition of the two systems during the middle devonian and the presence of the albury bega terrane both west and east of the macquarie arc in the eastern system that also includes the ocean floor narooma terrane and igneous ocean crust terrane s repetition of the albury bega terrane either side of the arc requires either rifting or orogen parallel strike slip duplication of a once contiguous package terrane interactions began in the earliest gisbornian with early docking uplift deformation and exchange of detritus amalgamation occurred in the earliest silurian benambran orogeny with accretion in the middle devonian over 40 myr discrete turbidite terranes aligned along the gondwana margin in two systems were converted into a very wide orogen characterized by the along strike juxtaposition of superficially similar terranes

direct observation of fault zone structure at the brittle ductile transition along the salzach ennstal mariazell puchberg fault system austrian alps 1 structural analysis of two key exposures reveals the architecture of the brittle ductile transition bdt of the subvertical strike slip salzachtal fault at lichtensteinklamm the fault zone is dominantly brittle with a 70 m wide high strain fault core highlighted by a 50 m thick highly foliated gouge zone in contrast at kitzlochklamm deformation is dominantly ductile albeit with relatively low strain indicated by weak lattice preferred orientations lpos the marked contrast in structural style indicates that these sites span the bdt the close proximity of the outcrops coupled with raman spectroscopy indicating similar maximum temperatures of 400 c suggests that the difference in exhumation depth is small with a commensurately small difference in total downdip width of the bdt the small strains indicated by weak lpos at kitzlochklamm coupled with evidence for brittle slip at the main fault contact and along the sides of a 5 m wide fault bounded sliver of klammkalk exposed 30 m into the grauwacken zone rocks suggest the possibility that this exposure may record hybrid behavior at different times during the earthquake cycle with ductile deformation occurring during slow interseismic slip and brittle deformation occurring during earthquakes as dynamic coseismic stresses induced a strain rate dependent shift to brittle fault behavior within the nominally ductile regime in the lower part of the bdt a key aspect of both outcrops is evidence of a high degree of strain localization through the bdt with high strain fault cores no wider than a few tens of meters

framework for susceptibility analysis of layered rock slopes considering the dimensions of the mapping units and geological data resolution at various map scales abstract in taiwan the failure of rock slopes has caused the catastrophic loss of lives and property to understand the risks associated with rock slope failure susceptibility analysis has been widely adopted as a fundamental task however currently most susceptibility analyses have investigated only landslide occurrences and have been limited to the regional scale in this case susceptibility maps cannot provide detailed information about the rock slope stability as required by the engineers to fill this gap this study developed a methodological framework to analyze the susceptibility of layered rock slopes from regional to local scales in each map scale the appropriate size of the slope unit su was produced as the mapping unit through the object based image analysis obia method and the susceptibility map was generated with an explicit purpose according to the resolution of geological data multiscale susceptibility analysis of layered rock slopes was performed in a metamorphic area in northern taiwan the performance of the susceptibility maps was validated by the field investigations and the data of the geologically sensitive area which were released by the central geological survey of taiwan the results show that different phases of the evaluation of rock slope stability were addressed including the landslide activity and the rock slope characterization on the regional scale and the failure mechanisms on the local scale in addition suitable sus can also be semiautomatically reproduced by the obia method with suggested strategies

statistical analysis of landslide susceptibility at yongin korea the aim of this study is to evaluate the susceptibility of landslides at yongin korea using a geographic information system gis landslide locations were identified in the yongin area from interpretation of aerial photographs field surveys and maps of the topography soil type timber cover and geology these data were collected and constructed into a spatial database using gis the factors that influence landslide occurrence such as slope aspect and curvature of topography were calculated from the topographic database texture material drainage and effective soil thickness were extracted from the soil database and type age diameter and density of timber were extracted from the forest database lithology was extracted from the geological database and land use was classified from the landsat tm satellite image landslide susceptibility was analyzed using the landslide occurrence factors by probability and logistic regression methods the results of the analysis were verified using the landslide location data the validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide location the gis was used to analyze the vast amount of data efficiently and statistical programs were used to maintain specificity and accuracy the results can be used to reduce associated hazards and to plan land use and construction

calibration and testing of an empirical chloritoid chlorite mg fe exchange thermometer and thermodynamic data for daphnite a compilation of literature data on the fe mg composition of coexisting chlorite and chloritoid from metapelites metamorphosed at various p t conditions shows that the logarithm of the fe mg partitioning lnkd varies linearly with the inverse of temperature from about 2 4 at 300 c to about 1 3 at 600 c in contrast no trend was observed with pressure and the molar volumes of mg and fe chlorite end members suggest that the pressure dependence of lnkd is not significant therefore the chloritoid chlorite mg fe exchange reaction is a potential thermometer and has been empirically calibrated using the analyses of 112 chloritoid chlorite pairs from 28 different localities temperatures estimated using the chl cld thermometer were checked against independent estimates for 20 samples not involved in the calibration beni mzala window morocco and the results are in fair agreement with independent temperature estimates however the analytical uncertainties and errors are too large to obtain reliable temperature estimates for extremely mg rich or fe rich compositions the chl cld thermometer is unreliable at xmg cld 0 8 at 700 c and xmg cld 0 9 at 300 c using the results of the empirical calibration we calculated new thermodynamic data for daphnite implementing these data it becomes possible to estimate t and p conditions of metamorphism for the invariant chlorite chloritoid quartz aluminosilicate assemblage that is widespread in low grade metapelites these estimates appear to be relevant only in the stability field of kyanite whereas the uncertainties on the calculated pressure conditions are very large in the stability field of kaolinite and pyrophyllite

evaluating volume of coseismic landslide clusters by flow direction based partitioning abstract a strong earthquake can trigger thousands of co seismic landslides the evaluation of the volume of such co seismic landslides is essential for landslide risk assessment and long term post earthquake hazard evaluation empirical volume area power laws are often applied to estimate the landslide volume when several small landslide deposits form a large cluster on the hillslope blurry boundaries of the clustered co seismic landslides may lead to seemingly one large landslide and grossly overestimated landslide volume in this paper we propose a flow direction based method to identify the boundaries of a cluster of landslides and to partition co seismic landslides three watersheds that were severely impacted by co seismic landslides in the wenchuan earthquake region are chosen for case studies each co seismic landslide cluster in these watersheds was interpreted from images taken shortly after the earthquake and partitioned into individual landslides in accordance with a flow direction map that is processed based on a local digital terrain model finally the volume of each individual landslide is calculated using an empirical volume area power law the adopted power law scaling relationship is selected from six widely used empirical relations and verified by 11 local landslide cases the proposed flow direction based partitioning method is further verified by clear boundaries of landslides that were exposed after storms as well as supplementary field survey results the proposed method results in similar landslide boundaries and volumes as the field survey results the uncertainty of this approach is below 19 if no partitioning is conducted the total volume of the landslide cluster can approach twice that from the field investigations

frequency and spatial distribution of landslides in a mountainous drainage basin western foothills taiwan maps from 1904 and 1915 and air photographs from 1963 1980 1985 1993 and 1996 provide a record of landslide incidence in a 92 1 km2 drainage basin a headwater tributary of the cho shui river in taiwan interpretation of landslide patterns from the early maps indicate that in four sub basins 36 km2 structural geological factors control chronic landsliding regularly reactivated by intense rains within these four sub basins all later air photographs reveal a continuing high incidence of landslides with landslide densities of 3 11 ha km2 air photographs taken in 1963 following extensive logging in 1985 following highway construction and in 1996 following the very large typhoon herb event demonstrate the short term effects of disturbance in these structurally weak sub basins air photographs from 1980 and 1993 demonstrate recovery of the land surface from logging and highway construction impacts respectively for the adjacent sub basins 56 km2 two modes of response to perturbations were identified six sub basins 48 km2 showed direct response to logging road construction and typhoon herb and five sub basins 8 km2 were more buffered and showed some lagged responses even this last category of sub basins is more active than the average for taiwan where the mean landslide density is 0 84 ha km2 it is proposed that for the 92 1 km2 hoshe basin the formative event sensu brunsden z geomorphol suppl 79 1990 1 is one that produces approximately 200 ha of landslides a value that has been equaled or exceeded in each of the periods of study 1963 1980 1980 1985 1985 1993 and 1993 1996 logging activity major road construction and extreme typhoon and earthquake events produce short term acceleration of landslide incidence in principle recovery rates of the land from pulsed perturbations of about 20 years for logging activity and about 8 years for major road construction may also be suggested

deformation zone jumps in a young convergent setting the lengguru fold and thrust belt new guinea island abstract the lengguru fold and thrust belt in west papua indonesia has all the characteristics of a young orogen involved in a rapidly changing tectonic setting the analysis of the young wedge shows however that its internal shortening has ceased recently and that it is nowadays suffering severe extension recent topographic data marine industrial seismic lines and drilling were used with field observations and measurements to create detailed cross sections and a new structural map the study allows us to distinguish two superimposed prisms composed of stacked mesozoic marine sediments of the australian margin against a crustal buttress the construction of these two wedges is younger than 11 myr the structures of the lengguru belt external zones are sealed by an unconformable clastic series indicating that the construction of the lengguru prism had aborted suddenly due to a change in the way the australian and pacific plate convergence was accommodated at that time the internal zones probably started to exhume and the tectonic regime became extensional nowadays the internal part of the lengguru fold and thrust belt is undergoing an active east west extension we believe that the extension observed in the lengguru wedge is coeval with a transition from a compressive to a transtensional regime illustrated in the central range of papua and the onset of the tarera aiduna and paniai left lateral faults the structure of the lengguru belt therefore results from events occurring over a very short time span a previous late miocene northeast southwest compression linked to the subduction process a second from middle miocene to early pliocene and a late pliocene quaternary global extension in the whole range the evolution is compared with that of the seram wedge and the misool onin kumawa continental ridge to the west where deformation is accommodated at a localized zone which jumps as convergence between australian and pacific plate proceeds this evolution of the belt reflects rapid changes in the accommodation oblique shortening with the isolated orogenic wedge of lengguru fold and thrust belt left to collapse this example illustrates the way a long lasting subduction terminates at the lithospheric scale the deformation remains rooted at the suture zone however at the surface the shortening is suddenly widespread over a large area during a very short time span formation of the lengguru belt prior to being transferred to another plate boundary

evaluating failure mechanisms of dip slope using a multiscale investigation and discrete element modelling abstract this study proposed an in depth multiscale analysis procedure to identify the dip slope area and assess dip slope stability and influencing area the proposed analysis procedure comprised five stages 1 identifying the potential area of a dip slope 2 analyzing the possible failure types of the dip slope 3 evaluating slope activity 4 analyzing dip slope stability under the influence of possible triggering factors and 5 assessment of the deformation and deposition area to validate the proposed procedure the chaochouhu region of taiwan was analyzed as a dip slope case in stages 1 to 3 the scale of the utilized map and the precision of associated data were evaluated to identify the potential area of a dip slope the possible failure types and the activity of each slope unit in stages 4 and 5 the processes of deformation and sliding in a high activity slope unit were simulated using the discrete element method the numerical model was first verified using in situ monitoring data obtained from inclinometers subsequently the model was used to predict the slope behavior under conditions of wetting deterioration of geomaterial the multiscale analysis revealed comprehensive information regarding the dip slope the application of the proposed approach would be useful to civil engineers for evaluating dip slope stability as well as to relevant authorities for planning hazard mitigation strategies

carbonaceous material in the ryoke metamorphic rocks kinki district japan abstract carbonaceous material in the ryoke pelitic metamorphic rocks in the wazuka area kinki district japan has been studied by x ray diffraction xrd analysis detrital graphite in the lower grade rocks is recognized in both x ray diffractograms and transmission electron micrographs progressive graphitization is considered to have proceeded continuously on the basis of the xrd data of the bulk concentrates of carbonaceous material and a conspicuous asymmetric shape of xrd peaks in lower grade samples is ascribed to the mixture of carbonaceous materials with different crystallinities fully ordered graphite does not occur until the highest grade part of the chlorite biotite zone the variation of degree of crystallinity of carbonaceous materials inferred from xrd data is consistent with the prograde mineral zones the temperatures for the development of fully ordered graphite are estimated to be between 410 and 440 c in regional metamorphism through comparing the xrd data from low medium and high pressure types of metamorphic terrains

landslide characteristics and slope instability modeling using gis lantau island hong kong steep terrain and high a frequency of tropical rainstorms make landslide occurrence on natural terrain a common phenomenon in hong kong this paper reports on the use of a geographical information systems gis database compiled primarily from existing digital maps and aerial photographs to describe the physical characteristics of landslides and the statistical relations of landslide frequency with the physical parameters contributing to the initiation of landslides on lantau island in hong kong the horizontal travel length and the angle of reach defined as the angle of the line connecting the head of the landslide source to the distal margin of the displaced mass are used to describe runout behavior of landslide mass for all landslides studied the horizontal travel length of landslide mass ranges from 5 to 785 m with a mean value of 43 m and the average angle of reach is 27 7 this gis database is then used to obtain a logistic multiple regression model for predicting slope instability it is indicated that slope gradient lithology elevation slope aspect and land use are statistically significant in predicting slope instability while slope morphology and proximity to drainage lines are not important and thus excluded from the model this model is then imported back into the gis to produce a map of predicted slope instability the results of this study demonstrate that slope instability can be effectively modeled by using gis technology and logistic multiple regression analysis