size distributions and failure initiation of submarine and subaerial landslides abstract landslides are often viewed together with other natural hazards such as earthquakes and fires as phenomena whose size distribution obeys an inverse power law inverse power law distributions are the result of additive avalanche processes in which the final size cannot be predicted at the onset of the disturbance volume and area distributions of submarine landslides along the u s atlantic continental slope follow a lognormal distribution and not an inverse power law using monte carlo simulations we generated area distributions of submarine landslides that show a characteristic size and with few smaller and larger areas which can be described well by a lognormal distribution to generate these distributions we assumed that the area of slope failure depends on earthquake magnitude i e that failure occurs simultaneously over the area affected by horizontal ground shaking and does not cascade from nucleating points furthermore the downslope movement of displaced sediments does not entrain significant amounts of additional material our simulations fit well the area distribution of landslide sources along the atlantic continental margin if we assume that the slope has been subjected to earthquakes of magnitude 6 3 regions of submarine landslides whose area distributions obey inverse power laws may be controlled by different generation mechanisms such as the gradual development of fractures in the headwalls of cliffs the observation of a large number of small subaerial landslides being triggered by a single earthquake is also compatible with the hypothesis that failure occurs simultaneously in many locations within the area affected by ground shaking unlike submarine landslides which are found on large uniformly dipping slopes a single large landslide scarp cannot form on land because of the heterogeneous morphology and short slope distances of tectonically active subaerial regions however for a given earthquake magnitude the total area affected by subaerial landslides is comparable to that calculated by slope stability analysis for submarine landslides the area distribution of subaerial landslides from a single event may be determined by the size distribution of the morphology of the affected area not by the initiation process

spatially integrated geodetic glacier mass balance and its uncertainty based on geostatistical analysis application to the western svartisen ice cap norway estimates of glacier mass balance using geodetic methods can differ significantly from estimates using direct glaciological field based measurements to determine if such differences are real or methodological there is a need to improve uncertainty estimates in both methods in this paper we focus on the uncertainty of geodetic methods and describe a geostatistical technique that takes into account the spatial correlation of the elevation differences when calculating spatially averaged elevation changes we apply this method to the western svartisen ice cap norway using elevation differences from the surrounding bedrock derived from stereophotogrammetry we show that the uncertainty is not only dependent on the standard error of the individual elevation differences but is also dependent on the size of the averaging area and the scale of the spatial correlation to assess if the geostatistical analysis made over bedrock is applicable to glacier surfaces we use concurrent photogrammetrical and laser scanning data from bedrock and a range of glacier surfaces to evaluate the dependency of the geostatistical analysis on the surface type the estimated geodetic mass balance and its uncertainty is 2 6 0 9 m w e for the period 1968 85 and 2 0 2 2 m w e for 1985 2002

self excitation process due to local seismic amplification responsible for the reactivation of the salcito landslide italy on 31 october 2002 1 an integrated numerical and geophysical approach was used to investigate the role of local seismic amplification in the reactivation of the salcito landslide italy after the molise earthquake of 31 october 2002 numerical stress strain analysis with flac 5 0 fdm software performed in dynamic configuration showed that the 1 hz frequency was consistent with landslide instability conditions the fourier spectrum of the triggering earthquake showed two main peaks occurring at 1 and 2 hz respectively which could be related to local effects the analysis of h v spectral ratios of ambient noise records obtained in the landslide area evidenced amplification effects in the 1 3 hz range on the basis of an engineering geology model numerical modeling of both 1 d and 2 d seismic wave propagation was conducted using linear and nonlinear solutions the simulation outputs showed 1 a 1 hz amplification ascribable to 2 d effects due to a landslide mass lying within a basin like geological structure 2 a double peak amplification at about 2 and 3 hz respectively ascribable to 1 d resonance of the landslide mass and 3 1 d plus lateral wave effects within the landslide mass in the 2 5 3 5 hz frequency range these findings suggest that local amplification of ground motion by the salcito landslide mass may generate a self excitation process responsible for its reactivation

present day south american climate abstract this paper documents the main features of the climate and climate variability over south america on the basis of instrumental observations gathered during the 20th century it should provide a modern reference framework for paleoclimate research in south america targeting high resolution proxies over the past few centuries several datasets suitable for present day climate research are first described highlighting their advantages as well as their limitations we then provide a basic physical understanding of the mean annual cycle of the precipitation and atmospheric circulation over the continent and the adjacent oceans in particular the diversity of precipitation temperature and wind patterns is interpreted in terms of the long meridional extent of the continent and the disruption of the large scale circulation caused by the andes cordillera the contrasting oceanic boundary conditions and the landmass distribution similarly the intensity and timing of the interannual and interdecadal climatic fluctuations exhibit considerable geographical dependence as some regions are more influenced by large scale phenomena rooted in the tropical oceans while others are more influenced by high latitude phenomena the impact of these large scale phenomena over south america is documented by a regression analysis between selected atmospheric indices and the precipitation and temperature fields we have included a discussion on the seasonality and long term stability of such impacts and complemented our general description by an updated review of the literature on climate variability over specific regions

extraordinary distance limits of landslides triggered by the 2011 mineral virginia earthquake the 23 august 2011 mineral virginia earthquake m w 5 8 was the largest to strike the eastern u s since 1897 and was felt over an extraordinarily large area although no large landslides occurred the shaking did trigger many rock and soil falls from steep river banks and natural cliffs in the epicentral area and from steep road cuts along and northwest of the blue ridge parkway we mapped the occurrence of rock falls to determine distance limits that could be compared with those from other documented earthquakes studies of previous earthquakes indicated a maximum epicentral distance limit for landsliding of 60 km for an m 5 8 earthquake the maximum distance limit for the 2011 earthquake was 245 km the largest exceedance of the historical limit ever recorded likewise the previous maximum area affected by landslides for this magnitude was 1500 km2 the area affected by landslides in the 2011 earthquake was 33 400 km2 these observations provide physical evidence that attenuation of strong shaking for eastern u s earthquakes is significantly lower than for plate boundary earthquakes also distance limits parallel to the regional structural trend are greater than those that transect the structure which suggests anisotropic attenuation related to the regional geologic structure peak ground acceleration pga at the landslide distance limits is estimated to have been about 0 02 0 04 g

multiarchive paleoseismic record of late pleistocene and holocene strong earthquakes in switzerland a multiarchive approach has been applied to the investigation of the late pleistocene and holocene record of strong earthquakes in switzerland the geological archives used for this study include active faults lake deposits slope instabilities and caves in the basle area eight trenches were opened across the basle reinach fault nearby rockfall deposits were systematically investigated sediment cores were taken from two lakes and nine caves were studied in central switzerland five lakes were investigated by means of high resolution seismic lines and sediment cores furthermore three caves were studied in central switzerland altogether the investigations are based on more than 350 km of high resolution reflection seismic lines 450 m of core samples 260 m of trenches and 245 radiocarbon age determinations the measured co seismic displacements along the basle reinach fault supply independent information for the magnitude of the ad 1356 basle earthquake exclusively based on geological evidence deformation features related to three well documented strong historic earthquake shocks were identified deformation features of the ad 1774 altdorf and ad 1601 unterwalden earthquakes can be used to calibrate paleoseismic evidence in central switzerland altogether traces of 13 earthquakes could be found in the two study areas all of them with magnitudes mw 6 or greater for the first time the earthquake catalogue for switzerland can be extended back beyond historic records into the late pleistocene spanning 15 000 years d 2005 elsevier b v all rights reserved

rockfalls triggered by the ad 1356 basle earthquake in the basle region of switzerland we demonstrate that rockfall blocks can be dated accurately using the radiocarbon method soil beneath rockfall blocks containing organic macro remains was sampled at four cliff sites in the tabular jura south east of basle a lightweight drilling rig drills a 101 mm diameter hole through rockfall blocks up to 6 m in height a downhole sampler is used to recover soil samples from below the blocks eighteen radiocarbon dates on charcoal wood needles of conifers and organic macro remains from 11 blocks gave dates between 970 and 440 bp calibrated ages range between ad 1210 and ad 1450 these results along with field observations and historical research suggest that a large number of blocks toppled as rockfalls within a short time interval in the epicentral area of the ad 1356 basle earthquake

rupture process of the 1987 superstition hills earthquake from the inversion of strong motion data a pair of significant earthquakes occurred on conjugate faults in the western imperial valley involving the through going superstition hills fault and the elmore ranch cross fault the first event was located on the elmore ranch fault m s 6 2 and the larger event on the superstition hills fault m s 6 6 the latter event is seen as a doublet teleseismically with the amplitudes in the ratio of 1 2 and delayed by about 8 sec this 8 sec delay is also seen in about a dozen strong motion records these strong motion records are used in a constrained least squares inversion scheme to determine the distribution of slip on a 2 d fault upon closer examination the first of the doublets was found to be itself complex requiring two episodes of slip thus the rupture model was allowed to have three separate subevents treated as separate ruptures with independent locations and start times the best fits were obtained when all three events initiated at the northwestern end of the fault near the intersection of the cross fault their respective delays are 2 1 and 8 6 sec relative to the first subevent and their moments are 0 4 0 9 and 3 5 10 25 dyne cm which is about half of that seen teleseismically this slip distribution suggests multi rupturing of a single asperity with stress drops of 60 200 and 15 bars respectively the first two subevents were confined to a small area around the epicenter while the third propagated 18 km southwestward compatible with the teleseismic and afterslip observations

microstructures of different soil layers caused by the high rise building group in shanghai the engineering characteristics of soils are controlled by the state of the microstructure of soils to a great extent with the withdrawal of groundwater controlled reasonably the engineering environmental effect of the high rise building group becomes the main cause of land subsidence in shanghai this paper studied the microstructure of each soil layer under the building loads in the centrifuge model by the scanning electron microscopy and the mercury intrusion porosimetry mip for qualitative analysis and quantitative analysis respectively the shape size and contact condition of the basic unit of the soil microstructure were analyzed the pore structure of each soil layer was studied by mip and the pore distribution of each soil layer was studied by the fractal theory the ink bottle effect exists in the intrusion stage in the mip test there are four different fractal dimensions for silty clay of layer no 4 and clayey soil of layer no 8 and three different fractal dimensions for silty sand of layer no 7 and layer no 9 the micro and macro mechanisms of land subsidence caused by the high rise building group were analyzed

hazardous processes and events from glacier and permafrost areas lessons from the chilean and argentinean andes glacier and permafrost hazards such as glacial lake outburst floods and rock ice avalanches cause significant socio economic damages worldwide and these processes may increase in frequency and magnitude if the atmospheric temperature rises in the extratropical andes nearly 200 human deaths were linked to these processes during the twentieth century we analysed bibliographical sources and satellite images to document the glacier and permafrost dynamics that have caused socio economic damages in this region in historic time including glacial lake outburst floods ice and rock ice avalanches and lahars to unravel their causes and geomorphological impacts in the extratropical andes at least 15 ice dammed lakes and 16 moraine dammed lakes have failed since the eighteenth century causing dozens of floods some floods rank amongst the largest events ever recorded 5000 106 m3 and 229 106 m3 respectively outburst flood frequency has increased in the last three decades partially as a consequence of long term decades to centuries climatic changes glaciers shrinkage and lake growth short term days to weeks meteorological conditions i e intense and or prolonged rainfall and high temperature that increased meltwater production have also triggered outburst floods and mass movements enormous mass failures of glaciers and permafrost 10 106 m3 have impacted lakes glaciers and snow covered valleys initiating chain reactions that have ultimately resulted in lake tsunamis and far reaching 50 km flows the eruption of ice covered volcanoes has also caused dozens of damaging lahars with volumes up to 45 106 m3 despite the importance of these events basic information about their occurrence e g date causes and geomorphological impact which is well established in other mountain ranges is absent in the extratropical andes a better knowledge of the processes involved can help to forecast and mitigate these events copyright 2014 john wiley sons ltd

calving processes and the dynamics of calving glaciers abstract calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world calving rates can increase dramatically in response to increases in velocity and or retreat of the glacier margin with important implications for sea level change despite their importance calving and related dynamic processes are poorly represented in the current generation of ice sheet models this is largely because understanding the calving problem involves several other long standing problems in glaciology combined with the difficulties and dangers of field data collection in this paper we systematically review different aspects of the calving problem and outline a new framework for representing calving processes in ice sheet models we define a hierarchy of calving processes to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events the first order control on calving is the strain rate arising from spatial variations in velocity particularly sliding speed which determines the location and depth of surface crevasses superimposed on this first order process are second order processes that can further erode the ice margin these include fracture propagation in response to local stress imbalances in the immediate vicinity of the glacier front undercutting of the glacier terminus by melting at or below the waterline and bending at the junction between grounded and buoyant parts of an ice tongue calving of projecting submerged ice feet can be regarded as a third order process because it is paced by first or second order calving above the waterline first order calving can be represented in glacier models using a calving criterion based on crevasse depth which is a function of longitudinal strain rate modelling changes in terminus position and calving rates thus reduces to the problem of determining the ice geometry and velocity distribution realistic solutions to the problem of modelling ice flow therefore depend critically on an appropriate choice of sliding law models that assume that basal velocities are controlled by basal drag can replicate much of the observed behaviour of calving glaciers with grounded termini but an important limitation is that they cannot be used to model floating glacier termini or ice shelves alternative sliding laws that parameterise drag from the glacier margins provide more flexible and robust ways of representing calving in ice sheet models such models can explain a remarkable range of observed phenomena within a simple unifying framework including downglacier increases in velocity and strain rates where basal and or lateral drag diminishes flow acceleration in response to thinning through time the tendency for glaciers to stabilise at pinning points in relatively shallow water or fjord narrowings the constraints on ice shelf stability and the contrasts in calving rates between tidewater and freshwater calving glaciers many unresolved issues remain however including the role played by the removal of backstress in the acceleration of retreating calving glaciers and the controls on melting at and below the waterline

swell and shrinkage characterizations of unsaturated expansive clays from texas abstract expansive soils have long been recognized as problematic because they cause failure to civil structures constructed above them the main problem of these soils can be attributed to poor understanding of the volume changes caused by moisture fluctuations current swell and shrinkage characterization models are limited by both the lack of standardized tests and tests that employ volume changes in uniaxial direction in the present research a comprehensive laboratory investigation was undertaken to study the volume change related swell shrinkage behaviors of five different types of expansive clayey soils sampled from various regions in texas usa extensive experimental programs consisting of basic chemical and mineralogical soil properties were first determined three dimensional free swell and shrinkage tests were performed on all soils at various compaction moisture content conditions soil water characteristic curves swccs of all test soils were determined by studying the suction potentials of these soils over a wide range of moisture contents volume change measurements of soils showed a good correlation with soil properties including plasticity and soil compaction properties swcc results also showed a clear variation in swcc profiles of soils with respect to soil plasticity overall a large database of soil properties was developed and is presented here it includes physical and mineralogical properties as well as engineering swell shrinkage and swcc test results

relation of landslides triggered by the kiholo bay earthquake to modeled ground motion abstract the 2006 kiholo bay hawaii earthquake triggered high concentrations of rock falls and slides in the steep canyons of the kohala mountains along the north coast of hawaii within these mountains and canyons a complex distribution of landslides was triggered by the earthquake shaking in parts of the area landslides were preferentially located on east facing slopes whereas in other parts of the canyons no systematic pattern prevailed with respect to slope aspect or vertical position on the slopes the geology within the canyons is homogeneous so we hypothesize that the variable landslide distribution is the result of localized variation in ground shaking therefore we used a state of the art high resolution ground motion simulation model to see if it could reproduce the landslide distribution patterns we used a 3d finite element analysis to model earthquake shaking using a 10 m digital elevation model and slip on a finite fault model constructed from teleseismic records of the mainshock ground velocity time histories were calculated up to a frequency of 5 hz dynamic shear strain also was calculated and compared with the landslide distribution results were mixed for the velocity simulations with some areas showing correlation of landslide locations with peak modeled ground motions but many other areas showing no such correlation results were much improved for the comparison with dynamic shear strain this suggests that 1 rock falls and slides are possibly triggered by higher frequency ground motions velocities than those in our simulations 2 the ground motion velocity model needs more refinement or 3 dynamic shear strain may be a more fundamental measurement of the decoupling process of slope materials during seismic shaking

remote sensing based assessment of hazards from glacier lake outbursts a case study in the swiss alps glacier lakes are a common phenomenon in high mountain areas outbursts from glacier lakes have repeatedly caused the loss of human lives as well as severe damage to local infrastructure in several high mountain ranges around the world a grave uncertainty about the hazard potential of glacier lakes still exists especially with respect to the effects of accelerating rates of glacier retreat as a consequence of atmospheric warming area wide detection and modeling of glacier lake hazard potentials is therefore a major challenge in this study an approach integrating three scale levels allows for the progressive focus on critical glacier lakes remote sensing methods for application in glacier lake hazard assessment are presented and include channel indexing data fusion and change detection each method matches the requirements of a certain scale level for estimating potential disaster amplitudes assessments must be made of maximum discharge and runout distance of outbursts floods and debris flows existing empirical relations are evaluated and complementary ones as derived from available data are proposed tests with observations from a recent outburst event from a moraine dammed lake in the swiss alps show the basic applicability of the proposed techniques and the usefulness of empirical relations for first hazard assessments in particular the observed runout distance of the debris flow resulting from the outburst does not exceed the empirically estimated maximum runout distance a list of decision criteria and related remote sensing techniques are discussed in conclusion such a list is an essential tool for evaluating the hazard potential of a lake a systematic application of remote sensing based methods for glacier lake hazard assessment is recommended

the 2015 chileno valley glacial lake outburst flood patagonia abstract glacial lake outburst floods glofs have become increasingly common over the past century in response to climate change posing risks for human activities in many mountain regions in this paper we document and reconstruct the sequence of events and impact of a large glof that took place in december 2015 in the chileno valley patagonia hydrograph data suggests that the flood continued for around eight days with an estimated total discharge of 105 6 106 m3 of water the sequence of events was as follows 1 a large debris flow entered the lake from two steep and largely non vegetated mountain gullies located northeast of the chileno glacier terminus 2 water displaced in the lake by the debris flow increased the discharge through the chileno lake outflow 3 lake and moraine sediments were eroded by the flood 4 eroded sediments were redistributed downstream by the glof the post glof channel at the lake outlet widened in some places by 130 m and the surface elevation of the terrain lowered by a maximum of 38 8 1 5 m farther downstream large amounts of entrained sediment were deposited at the head of an alluvial plain and these sediments produced an 340 m wide fan with an average increase in surface elevation over the pre glof surface of 4 6 1 5 m we estimate that around 3 5 million m3 of material was eroded from the flood affected area whilst over 0 5 million m3 of material was deposited in the downstream glof fan the large debris flow that triggered the glof was probably a paraglacial response to glacier recession from its little ice age limits we suggest that glofs will continue to occur in these settings in the future as glaciers further recede in response to global warming and produce potentially unstable lakes detailed studies of glof events are currently limited in patagonia and the information presented here will therefore help to inform future glacial hazard assessments in this region

quantitative estimation of clay mineralogy in fine grained soils stabilization design guidelines based on soil plasticity properties have certain limitations soils of similar plasticity properties can contain different dominant clay minerals and hence their engineering behavior can be different when stabilized with the same chemical additive and dosage it is essential to modify stabilizer design guidelines by including clay mineralogy of the soil and its interactions with chemical additives used chemical properties of a soil including cation exchange capacity cec specific surface area ssa and total potassium tp are dependent on clay mineral constituents and an attempt is made in this study to develop a rational and practical methodology to determine both clay mineralogy distribution and dominant clay mineral in a soil by using three measured chemical soil properties and their analyses this approach has been evaluated by determining and evaluating clay minerals present in artificial and natural clayey soils of known and unknown clay mineralogy a total of twenty natural and six artificial soils were considered and used in the chemical analyses test results and subsequent analyses including the development of artificial neural network ann based models are evaluated and described in this paper

statistical approach to earthquake induced landslide susceptibility susceptibility analysis for predicting earthquake induced landslides has most frequently been done using deterministic methods multivariate statistical methods have not previously been applied in this study however we introduce a statistical methodology that uses the intensity of earthquake shaking as a landslide triggering factor this methodology is applied in a study of shallow earthquake induced landslides in central western taiwan the results show that we can accurately interpret landslide distribution in the study area and predict the occurrence of landslides in neighboring regions this susceptibility model is capable of predicting shallow landslides induced during an earthquake scenario with similar range of ground shaking without requiring the use of geotechnical groundwater or failure depth data

near source attenuation of peak horizontal acceleration strong motion data recorded within 50 km of the rupture zone were used to study near source attenuation characteristics of horizontal peak ground acceleration for worldwide earthquakes of magnitudes 5 0 to 7 7 the data base consisted of 229 horizontal components of peak acceleration recorded from 27 earthquakes including the 15 october 1979 imperial valley earthquake these data were found to be adequately represented by the functional relationship pga a exp b m r c m d where pga represents the mean of the peak values scaled from the two horizontal components of each recording m is richter magnitude and r is distance from the fault rupture zone peak acceleration was found to be lognormally distributed with a standard error representing a 45 per cent increase in the median estimate the regression analysis statistically confirmed the results of earthquake simulation studies that have predicted peak acceleration to become independent of magnitude and distance in the near field an extensive sensitivity study showed that predictions based on our attenuation relationships are stable with respect to reasonable model and parameter variations an analysis of residuals was used to investigate the behavior of peak acceleration with respect to various earthquake site and recording parameters the more significant findings being 1 a similarity in the level of acceleration recorded on soil or rock 2 larger than average accelerations recorded at sites located on shallow soils or in areas of steep topography 3 larger than average accelerations associated with earthquakes having reverse fault mechanisms and 4 lower than average accelerations recorded in large embedded structures

control of hazard due to seismicity induced by a hot fractured rock geothermal project in 2003 hydraulic stimulations were carried out in a geothermal field in eastern el salvador central america as part of a project to explore the feasibility of commercial hot fractured rock energy generation a key requisite for this environmentally friendly energy source is that the fracturing of the hot rocks at depths of 1 2 km must not produce levels of ground shaking at the surface that would present a serious disturbance or threat to the local population thresholds of tolerable ground motion were inferred from guidelines and regulations on tolerable levels of vibration and from correlations between instrumental strong motion parameters and intensity considering the vulnerability of the exposed housing stock the thresholds were defined in terms of peak ground velocity pgv and incorporated into a traffic light system that also took account of the frequency of occurrence of the induced earthquakes the system was implemented through a dedicated seismograph array and locally derived predictive equations for pgv the traffic light was used as a decision making tool regarding the duration and intensity of pumping levels during the hydraulic stimulations the system was supplemented by a small number of accelerographs and re calibrated using records obtained during the rock fracturing

flotation and retreat of a lake calving terminus mendenhall glacier southeast alaska usa mendenhall glacier is a lake calving glacier in southeastern alaska usa that is experiencing substantial thinning and increasingly rapid recession long term mass wastage linked to climatic trends is responsible for thinning of the lower glacier and leaving the terminus vulnerable to buoyancy driven calving and accelerated retreat bedrock topography has played a major role in stabilizing the terminus between periods of rapid calving and retreat lake terminating glaciers form a population distinct from both tidewater glaciers and polar ice tongues with some similarities to both groups lacustrine termini experience fewer perturbations e g tidal flexure high subaqueous melt rates and are therefore inherently more stable than tidewater termini at mendenhall rapid thinning and simultaneous retreat into a deeper basin led to flotation conditions along approximately 50 of the calving front this unstable terminus geometry lasted for approximately 2 years and culminated in large scale calving and terminus collapse during summer 2004 buoyancy driven calving events and terminus break up can result from small rapidly applied perturbations in lake level

assessment of the effects of historical strong earthquakes on large scale landslide groupings in the wei river midstream abstract regional active tectonics and historical earthquake records indicate the importance of the triggering effects of historical strong earthquakes on groups of large scale landslide occurrences in the wei river midstream section in this study a method to assess the triggering effects of historical earthquakes on regional large scale landslides is presented the greatest epicentral distances of seismically induced landslides were calculated the triggering effects of four key historical strong earthquakes with epicenters within 300 km of the wei river midstream section were analyzed these are the ms 7 0 qishan earthquake of 780 bce the ms 8 0 tianshui earthquake of 1654 ce the ms 8 25 huaxian earthquake of 1556 ce and the ms 8 5 haiyuan earthquake of 1920 ce taking the qishan earthquake as an example a seismically induced landslide displacement and hazard assessment method based on the newmark displacement model was developed the degree of spatial matching of the results for historical earthquake triggered landslides and the distribution of actual large scale landslide deposits were compared quantitatively using the success rate curve method the results show that of the four historical earthquakes the tianshui earthquake had the strongest effect of inducing large scale landslides regionally along the wei river midstream section

evaluation of swell behavior of expansive clays from internal specific surface and pore size distribution abstractthe interdependency of microsoil fabric related properties and swell shrink behavior of expansive soils needs to be identified to achieve a more thorough and accurate prediction of heave of expansive soils in a recent research study two microsize related properties of a soil pore size distribution and specific surface area were identified and examined in an effort to address their synergistic effects on swelling behavior of soils to study this aspect in detail eight natural expansive clayey soils from known expansive soil regions were sampled and studied by using two test methods conventional one dimensional vertical swell tests and novel three dimensional volumetric swell strain tests microinternal structural details including pore void distribution were obtained from mercury intrusion porosimetry mip studies on compacted soil specimens specific surface area ssa details of the same soils were determined using the chemical ethylene glycol monoethyl ether egme method attempts were m

thermo erosional notch development at fresh water calving tasman glacier new zealand controls on glacier calving rates are receiving increased scientific interest at fresh water calving glaciers limnological factors might be more important than glaciological ones measurements of thermo erosional notch development at the calving ice cliff of tasman glacier new zealand suggest that the calving rates at this glacier are directly controlled by the rate of thermal undercutting notch formation rates typically vary between 10 and 30 cm d 1 maximum rate 65 cm d 1 in summer corresponding to an average calving rate of 34 m a 1 notch formation is slower than waterline melt and is controlled by water temperatures and circulation cliff geometry debris supply and water level fluctuations the latter shift the position of undercutting resetting the level of the notch formation process and thereby slowing it the geometry of the notch and the debris supply determine the extent of influence of the lake on notch water temperatures and circulation hence water temperatures in the lake are not necessarily indicative of the rate of notch formation the prediction of rate of notch formation from far field variables is hampered by the complex interaction of the influencing factors the significance of thermal undercutting as a calving rate controlling process decreases with increasing ice velocities calving rates and surface gradients

slope stabilization and landslide size on mt 99 peaks after chichi earthquake in taiwan the study focuses on the landslide characteristics of mt 99 peaks in nantou county the most serious landslide prone area caused by chichi earthquake in taiwan several investigations and field surveys were made on mt 99 peaks for 5 years to research the landslide area and depth rainfall trend and slope stabilization the total landslide volume caused by the earthquake on mt 99 peaks was about 1 47 106 m3 and the mean landslide thickness was about 0 22 m gravel layers with a volume of more than 80 of total soil profile dominated mt 99 peaks the landslide on mt 99 peaks was induced by heavy rainfall from july to september because the rainfall on mt 99 peaks had a nonuniform distribution in time although the vegetation recovery on mt 99 peaks was in progress the soil slope had remained unstable as a result typhoon mindulle occurred in july 2004 collapsed the hillslope again after 5 years of chichi earthquake this study suggests that vegetation recovery on mt 99 peaks for 5 years was insufficient to stabilize the landslide affected area

assessment of earthquake induced landslide hazard in greece from arias intensity to spatial distribution of slope resistance demand abstract the earthquake induced landslide hazard in greece is evaluated by means of a parametric time probabilistic approach first by taking into account the characteristics of seismicity affecting greece we calculated occurrence probabilities for different levels of seismic shaking expressed in terms of arias intensity for a time interval of 50 yrs then by utilizing the linkage of newmark displacement with arias intensity and critical acceleration we mapped the spatial distribution of the slope strength demand that imply a 10 probability that displacement will exceed critical thresholds for potential seismic triggering of incoherent and coherent landslides the obtained results suggest that the areas of western greece and the broader region of the gulf of corinth are the most exposed to conditions of seismic triggering of both kinds of landslides the derived slope strength demand maps could provide the basis for the assessment of whether particular slopes have a significant failure probability by comparing the estimated strength demand with the actual critical acceleration values calculated from slope material properties and slope angle we exemplified this approach at a coastal area of the western gulf of corinth where by considering situations expected in dry and wet periods we also demonstrated that earthquake effects on slope stability depend on the season of earthquake occurrence

spatial and temporal variability of air temperature on a melting glacier atmospheric controls extrapolation methods and their effect on melt modeling juncal norte glacier chile 1 temperature data from three automatic weather stations and twelve temperature loggers are used to investigate the spatiotemporal variability of temperature over a glacier its main atmospheric controls the suitability of extrapolation techniques and their effect on melt modeling we use data collected on juncal norte glacier central chile during one ablation season we examine temporal and spatial variability in lapse rates lrs together with alternative statistical interpolation methods the main control over the glacier thermal regime is the development of a katabatic boundary layer kbl katabatic wind occurs at night and in the morning and is eroded in the afternoon lrs reveal strong diurnal variability with steeper lrs during the day when the katabatic wind weakens and shallower lrs during the night and morning we suggest that temporally variable lrs should be used to account for the observed change they tend to be steeper than equivalent constant lrs and therefore result in a reduction in simulated melt compared to use of constant lrs when extrapolating from lower to higher elevations in addition to the temporal variability the temperature elevation relationship varies also in space differences are evident between local lrs and including such variability in melt modeling affects melt simulations extrapolation methods based on the spatial variability of the observations after removal of the elevation trend such as inverse distance weighting or kriging do not seem necessary for simulations of gridded temperature data over a glacier

rupture process of the ms 6 6 superstition hills california earthquake determined from strong motion recordings application of tomographic source inversion abstract we analyze strong motion recordings of the m s 6 6 superstition hills earthquake to determine the timing location spatial extent and rupture velocity of the subevents that produced the bulk of the high frequency 0 5 to 4 hz seismic energy radiated by this shock the earthquake can be characterized by three principal subevents the largest ones occurring about 3 and 10 sec after initiation of rupture timing relationships between pulses on the seismograms indicate that the three subevents are located within 8 km of each other along the northern portion of the superstition hills fault the two largest subevents display different directivity effects we apply a tomographic source inversion to the integrated accelerograms to determine the slip acceleration on the fault as a function of time and distance based on a one dimensional fault model the azimuthal distribution of amplitudes for the second subevent can be largely explained by a rupture that propagated about 2 km to the southeast along the superstition hills fault at a velocity about equal to the p wave velocity an alternative model with rupture propagating to the northeast along a conjugate fault plane can also account for the observed directivity of this subevent but it is not supported by the aftershock distribution the third subevent ruptured to the southeast along an 8 km long portion of the superstition hills fault at about the shear wave velocity this rupture propagation caused the relatively large accelerations and velocities observed in strong motion records for stations southeast of the hypocenter the long time intervals between the subevents and their relative proximity to each other indicate a very slow component to the rupture development the southern half of the superstition hills fault did not generate significant high frequency strong ground motion although it showed substantial co seismic surface displacement the subevents are situated along the same northern portion of the fault where most of the aftershocks are located the locations of the subevents appear to be controlled by bends in the fault mapped at the surface and by changes in basement structure at depth

using an ultra long range terrestrial laser scanner to monitor the net mass balance of urumqi glacier no 1 eastern tien shan china at the monthly scale we describe the use of a terrestrial laser scanner tls to monitor the net mass balance of urumqi glacier no 1 eastern tien shan we used an ultra long range riegl vz 6000 tls which is specially designed for surveying snow and ice covered terrain to create repeated high spatiotemporal resolution dems focusing on the monthly scale 25 april 28 may 2015 net mass balance according to the tls derived dems the area of urumqi glacier no 1 was 1 558 km 2 on 25 april 2015 and the average surface elevation change was 0 225 m by comparing the results from the use of tls with the conventional glaciological mass balance method the correlation coefficient r 2 between glaciological elevation changes of individual stakes and the tls derived geodetic elevation change of corresponding points was 0 85 considering the uncertainty of both methods this is a promising result using the in situ measured snow densities snow pits of the glacier surface the geodetic net mass balance was 0 074 m w e which is slightly positive the mean uncertainty in the tls derived monthly net mass balance was 0 018 m w e showing that the tls surveying system presented accurate and relevant results and is therefore suitable to monitor mass balance evolution of mountain glaciers

spatial variability and attenuation of arias intensity during the 1999 chi chi mw 7 6 earthquake taiwan arias intensity is a measure of earthquake intensity that captures the potential destructiveness of an earthquake using the strong ground motion records of the m w 7 6 chi chi earthquake taiwan we analyze the spatial distribution of the vertical horizontal fault parallel and fault normal components of the arias intensity we investigate the effects of the hanging wall and footwall on ground motions and develop a relationship between arias intensity and peak ground acceleration pga incorporating the influence of local site conditions we also evaluate the applicability of some widely used arias intensity attenuation relationships by comparing the observed values with empirical estimates our results show the vertical arias intensity is generally lower than the horizontal component with nearly 90 of the vertical to horizontal ratios between 0 1 and 0 6 during this typical reverse mechanism earthquake the fault normal component of the arias intensity is approximately 20 higher than the fault parallel component for sites within 40 km of the fault arias intensities on the hanging wall are systematically higher than those on the footwall indicating clear hanging wall effects site conditions influence the correlation between arias intensity and pga arias intensity shows a good correlation with pga and v s 30 arias intensity increases with increasing pga and decreasing v s 30 the arias intensities observed within 40 km of site class c locations and within 80 km of site class d locations are generally lower than the mean estimates from empirical predictions in contrast at distances of 80 km from site class d locations the observed arias intensities are much larger than the empirical predictions as a result of site amplification considering the variability of ground motion between earthquakes the attenuation model of travasarou et al 2003 model 4 of stafford et al 2009 and the model of lee et al 2012 provide a good fit with observations from the chi chi earthquake online material table of station coordinates fault distances footwall hanging wall indicator site classes v s 30 and measured arias intensities

the interaction of seismic waves with step like slopes and its influence on landslide movements abstract the interaction of seismic waves with slopes is a major factor influencing landslide movements that involve slope stability local site seismic amplification and topographic effects affecting ground motion the results of a numerical study of landslide movements induced by the interaction of seismic waves with step like slopes are presented here to investigate this input slope interaction a dynamic analysis was performed using the finite difference stress strain numerical code flac 6 0 under visco plastic conditions the dynamic signals were selected to be representative of different peak ground accelerations pgas arias intensities and frequency contents and they were used in a parametric study of different step like slopes with different geometrical configurations in terms of dip height and thickness of geological strata the derived outputs were processed for a seismic amplification analysis and to evaluate the induced stress strain effects in terms of progressive failure and resulting displacements the obtained results i describe a fundamental role of topography in amplifying or de amplifying the seismic ground motion ii demonstrate that the progressive failure of unsheared slopes influences the seismic amplification iii show that the strain effects on unsheared slopes in terms of progressive failure are more intense with increasing arias intensity and slope dip iv prove that amplification or de amplification processes can justify the values of displacements involving pre existing landslide masses which are significantly different with respect to those expected on the basis of sliding block approaches i e newmark s and flexible sliding block methods v highlight that in the geological setting considered here the seismically induced displacements arising from the reactivation of pre existing landslide masses can be significantly underestimated by sliding block approaches in the case of low angle slopes characterised by high k values i e the ratios between the critical pseudostatic threshold ky of the landslide and pgas of the applied seismic input

ground motions at the outermost limits of seismically triggered landslides abstract over the last few decades we and our colleagues have conducted field investigations in which we mapped the outermost limits of triggered landslides in four earthquakes 1987 whittier narrows california m 5 9 1987 superstition hills california m 6 5 1994 northridge california m 6 7 and 2011 mineral virginia m 5 8 in an additional two earthquakes 1976 guatemala m 7 5 and 1983 coalinga california m 6 5 we determined limits using high resolution aerial photographic interpretation in conjunction with more limited ground investigation limits in these earthquakes were defined by the locations of the very smallest failures 3 from the most susceptible slopes that can be identified positively as having been triggered by earthquake shaking because we and our colleagues conducted all of these investigations consistent methodology and criteria were used in determining limits in the six earthquakes examined we correlated the outermost landslide limits with peak ground accelerations pgas from shakemap models of each earthquake for the four earthquakes studied by field investigation the minimum pga values associated with farthest landslide limits ranged from 0 02 g to 0 08 g the range for the two earthquakes investigated using aerial photographic interpretations was 0 05 0 11 g although pga values at landslide limits depend on several factors including material strength topographic amplification and hydrologic conditions these values provide an empirically useful lower limiting range of pga needed to trigger the smallest failures on very susceptible slopes in a well recorded earthquake this pga range can be used to identify an outer boundary within which we might expect to find landsliding in earthquakes that are not well recorded mapping the outermost landslide limits provides a useful clue about ground motion levels at the mapped limits

statistical evaluation of the effect of earthquake with other related factors on landslide susceptibility using the watershed area of shihmen reservoir in taiwan as a case study landslide susceptibility evaluation is one of the most important issues in watershed management after an earthquake the landslide susceptibility decreases functionally with increases in the distance from the epicenter under the same rainfall intensity landslides are more likely to occur in an area where earthquakes occur more frequently however the questions of how much an earthquake should be weighted and how to evaluate the effects of an earthquake still need to be studied to understand how earthquakes affect rainfall triggered landslides the horizontal peak ground acceleration pga data from the central weather bureau seismic network is used as the earthquake factor and combined with other factors to determine the weight of earthquakes in landslide susceptibility using logistic regression the results indicate that the ability of landslide prediction is better when considering the earthquake factor this study also proved that although there are no co seismic landslides after earthquakes in the study area the earthquake factor is still required to increase the model accuracy pga has been described as a usable factor in areas with frequent earthquakes and high geological activity when using historical data to evaluate landslide susceptibility the earthquake factor should be taken into consideration to prevent errors

teleseismic source parameters and rupture characteristics of the 24 november 1987 superstition hills earthquake long period body waves from the 24 november 1987 superstition hills earthquake are studied to determine the focal mechanism and spatial extent of the seismic source the earthquake is a complex event consisting of two spatially distinct subevents with different focal mechanisms two consistent models of rupture are developed for both models the second subevent begins 8 sec after the initiation of the first subevent and the preferred centroid depth lies between 4 to 8 km model 1 consists of two point sources separated by 15 to 20 km along strike of the superstition hills fault model 2 consists of one point source and one line source with a rupture velocity of 2 5 km sec with moment release distributed along strike of the focal plane at a distance of 10 to 22 km from the epicenter these moment release patterns show that a significant amount of long period energy is radiated from the southern segment of the fault total moment release for both models is approximately 8 10 25 dyne cm both models also suggest a change of dip from near vertical near the epicenter to steeply southwesterly dipping along the southern segment of the fault the difference in rupture characteristics and fault dips seen teleseismically is also reflected in aftershock and afterslip data and crustal structure underlying the two fault segments the northern segment had more aftershocks and a smaller proportion of afterslip than the southern segment the boundary between the two segments lies at a step in the basement that separates a deeper metasedimentary basement to the south from a shallower crystalline basement to the north

a preliminary probabilistic seismic hazard assessment in terms of arias intensity in southeastern spain financiado por el grupo de investigacion peligrosidad sismica y microzonificacion de la junta de andalucia rnm 0217 y por el proyecto de la cicyt ries ctidib 2002 177

glacier inventory and recent glacier variations in the andes of chile south america the first satellite derived inventory of glaciers and rock glaciers in chile created from landsat tm etm images spanning between 2000 and 2003 using a semi automated procedure is presented in a single standardized format large glacierized areas in the altiplano palena province and the periphery of the patagonian icefields are inventoried the chilean glacierized area is 23 708 1185 km 2 including 3200 km 2 of both debris covered glaciers and rock glaciers glacier distribution varies as a result of climatic gradients with latitude and elevation with 0 8 occurring in the desert andes 17 30 32 s 3 6 in the central andes 32 36 s 6 2 in the lakes district and palena province 36 46 s and 89 3 in patagonia and tierra del fuego 46 56 s glacier outlines across all glacierized regions and size classes updated to 2015 using landsat 8 images for 98 complexes indicate a decline in areal extent affecting mostly clean ice glaciers 92 3 4 6 km 2 whereas debris covered glaciers and rock glaciers in the desert and central andes appear nearly unchanged in their extent glacier attributes estimated from this new inventory provide valuable insights into spatial patterns of glacier shrinkage for assessing future glacier changes in response to climate change

melt and surface sublimation across a glacier in a dry environment distributed energy balance modelling of juncal norte glacier chile previous estimates of melt and surface sublimation on glaciers of the subtropical semiarid andes 29 34 s have been obtained at few specific locations but it is not clear how ablation components vary across the entire extent of a glacier in this dry environment here we simulate the distributed energy and mass balance of juncal norte glacier 33 s during a 2 month summer period forcing fields of near surface air temperature and wind speed are generated using two methods accounting for the main physical processes that shape their spatial variations simulated meteorological variables and ablation agree well with observations on the glacier tongue and reveal complex patterns of energy and mass fluxes ablation decreases from 70 mm w e d 1 at the low albedo glacier terminus 3000 m where almost 100 of total ablation corresponds to melt to 75 of total ablation our simulations provide the first glacier scale estimates of ablation components on a glacier in the study region and better reproduce the observed and expected spatial variations of melt and surface sublimation in comparison with more simple assumptions such as linear gradients and uniform wind speeds

glacier area changes in the central chilean and argentinean andes 1955 2013 14 to improve our knowledge of glacier area changes in the central chilean and argentinean andes 32 9 s 33 4 s two new glacier inventories from 1989 to 2013 14 are compared with a reinterpreted inventory from 1955 comparisons show glacier area retreat of 30 3 since 1955 decreasing from 134 to 94 km2 in 2013 14 whilst the annual rate of area loss showed a small increase insignificant between the periods of 1955 1989 and 1989 2013 14 separate analysis of the 1989 and 2013 14 inventories including a larger sample revealed a higher rate of glacier change compared with the smaller samples of these inventories additionally an analysis at 5 year intervals for six major glaciers 1955 2013 indicates large variability in response times and area loss magnitudes glacier olivares alfa for example lost 63 of its ice area while the juncal norte glacier lost only 10 1955 2013 the findings from this study improve our current knowledge base concerning widespread glacier decline in the southern andes and furthers monitoring efforts in this poorly described region of the world a region containing vital water resources for populated areas in south america

spatial distribution of landslides triggered from the 2007 niigata chuetsu oki japan earthquake abstract understanding the spatial distribution of earthquake induced landslides from specific earthquakes provides an opportunity to recognize what to expect from future events the july 16 2007 mw 6 6 mjma 6 8 niigata chuetsu oki japan earthquake triggered hundreds of landslides in the area surrounding the coastal city of kashiwazaki and provides one such opportunity to evaluate the impacts of an offshore magnitude 6 earthquake on a steep coastal region as part of a larger effort to document all forms of geotechnical damage from this earthquake we performed landslide inventory mapping throughout the epicentral area and analyzed the resulting data for spatial seismic motion and geologic correlations to describe the pattern of landsliding coupled with examination of a third party aerial photo based landslide inventory our analyses reveal several areas of high landslide concentration that are not readily explained by either traditional epicentral and fault plane distance metrics or by recorded and inferred ground motions whereas average landslide concentrations averaged less than 1 landslide per square kilometer ls km2 some areas reached up to 2 ls km2 in the nishiyama hills to the northeast of kashiwazaki and between 2 and 11 ls km2 in coastal areas to the north and south of the city correlation with seismometer based and monument overturning back calculated ground motions suggests that a minimum peak ground acceleration pga of approximately 0 2 g was necessary for landsliding throughout the region but does not explain the subregional areas of high landslide concentration however analysis of topographic slope and the distribution of generally weak dip slope geologic units does sufficiently explain why on a sub regional scale high landslide concentrations occurred where they did these include 1 an inland region of steep dip slope anticlinal sedimentary strata with associated fold belt compression and uplift of the anticline and 2 coastal areas with generally weaker weathered outcrop lithology and steeper slopes resulting from active marine and terrestrial cliff processes the results offer lessons for understanding the effects of earthquakes on both regional and subregional scales with regard to the spatial distribution of landsliding

regional cooling in a warming world recent temperature trends in the southeast pacific and along the west coast of subtropical south america 1979 2006 1 while it is widely accepted that the global mean atmospheric temperature has increased in recent decades the spatial distribution of global warming has been complex in this study we comprehensively characterize the spatial pattern including vertical structure of temperature trends along the subtropical west coast of south america continental chile for the period 1979 2006 and examine their consistency with expectations based on the cmip 3 ensemble of coupled ocean atmosphere simulations for the late 20th century in central and northern chile 17 37 s the most notable feature is a strong contrast between surface cooling at coastal stations 0 2 c decade and warming in the andes 0 25 c decade only 100 200 km further inland coastal radiosonde data imply that the coast andes variation is largely due to strong vertical stratification of temperature trends in the atmosphere west of the andes the coastal cooling appears to form part of a larger scale la nina like pattern and may extend below the ocean mixed layer to depths of at least 500 m over continental chile the cmip 3 gcm ensemble predicts temperature trends similar to those observed in the andes the cooling along the chilean coast is not reproduced by the models but the mean sst warming is weaker there than any other part of the world except the southern ocean it is proposed that the intensification of the south pacific anticyclone during recent decades which is also a simulated consequence of global warming is likely to play a major role in maintaining cooler temperatures off the coast of chile

rapid expansion of glacial lakes caused by climate and glacier retreat in the central himalayas glacial lake outburst floods are among the most serious natural hazards in the himalayas such floods are of high scientific and political importance because they exert trans boundary impacts on bordering countries the preparation of an updated inventory of glacial lakes and the analysis of their evolution are an important first step in assessment of hazards from glacial lake outbursts here we report the spatiotemporal developments of the glacial lakes in the poiqu river basin a trans boundary basin in the central himalayas from 1976 to 2010 based on multi temporal landsat images studied glacial lakes are classified as glacier fed lakes and non glacier fed lakes according to their hydrologic connection to glacial watersheds a total of 119 glacial lakes larger than 0 01km 2 with an overall surface area of 20 22km 2 10 8 were mapped in 2010 with glacier fed lakes being predominant in both number 69 58 0 and area 16 22km 2 80 2 we found that lakes connected to glacial watersheds glacier fed lakes significantly expanded 122 1 from 1976 to 2010 whereas lakes not connected to glacial watersheds non glacier fed lakes remained stable 2 8 during the same period this contrast can be attributed to the impact of glaciers retreating glaciers not only supply meltwater to lakes but also leave space for them to expand compared with other regions of the hindu kush himalayas hkh the lake area per glacier area in the poiqu river basin was the highest this observation might be attributed to the different climate regimes and glacier status along the hkh the results presented in this study confirm the significant role of glacier retreat on the evolution of glacial lakes copyright c 2014 john wiley sons ltd

earthquake induced landslides in central america central america is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides data are presented for earthquake triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude we find that the areas affected by landslides are similar to other parts of the world but in certain parts of central america the numbers of slides are disproportionate for the size of the earthquakes we also find that there are important differences between the characteristics of landslides in different parts of the central american isthmus soil falls and slides in steep slopes in volcanic soils predominate in guatemala and el salvador whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in costa rica and panama methods for assessing landslide hazards considering both rainfall and earthquakes as triggering mechanisms developed in costa rica appear not to be suitable for direct application in the northern countries of the isthmus for which modified approaches are required

regional arias intensity attenuation relationship for taiwan considering vs30 the arias intensity is a measure of earthquake intensity arrived at through the integration of a square of the acceleration time history it has been demonstrated to be an effective predictor of earthquake damage potential in relation to short period structures liquefaction and seismic slope stability and has begun to be considered as a ground motion measure suitable for use in probabilistic seismic hazard analysis psha as well as earthquake loss estimation a new empirical arias intensity attenuation relationship for shallow crustal earthquakes is developed where both fault type and a continuous site variable vs30 are considered the relationship is based on a large number of strong motion records 6570 from a wide range of earth quake magnitudes 3 9 7 6 from the taiwan strong motion instrument program tsmip network its functional form is modified from that of travasarou et al 2003 which is derived from a point source model and the coefficients are determined through nonlinear regression analyses using a mixed effects model the results show that the incorporation of vs30 can significantly reduce regression error the arias intensity value predicted in the present study is generally similar to that obtained by travasarou et al 2003 but is different in detail being more suitable for usage in psha for a tectonically young orogenic belt like that in taiwan or new zealand

long term glacier variations in the central andes of argentina and chile inferred from historical records and tree ring reconstructed precipitation abstract snow and ice in the central andes of chile and argentina 33 36 s are the major source of water for the highly populated regions near the cities of santiago and mendoza however our knowledge of the forces driving the general glacier retreat in the region is limited in order to obtain a long term perspective of glacier fluctuations and their relationships with climate in the central andes historical glacier variations were documented and compared with a tree ring precipitation reconstruction based upon austrocedrus chilensis trees a multi proxy approach historical documents old aerial photographs and satellite imagery was used to map the fluctuations of eight glaciers including the cipreses glacier which provides the oldest record of glacier variations in the region starting in ad 1842 all the studied glaciers exhibited a negative trend during the 20th century with mean frontal retreats between 50 and 9 m y 1 thinning rates between 0 76 and 0 56 m y 1 and a mean ice area reduction of 3 since 1955 more than 350 tree ring cores were combined into three tree ring chronologies which strongly correlate with the instrumental precipitation in santiago de chile 33 26 s 70 41 w 520 m asl based on these records a 712 year precipitation reconstruction was developed this reconstruction is characterised by a centennial oscillation indicating marked dry conditions around the years 1440 and 1600 ad wet conditions were prevalent in the years 1500 1650 and particularly around 1850 ad since this precipitation maximum the reconstruction shows a clear secular decreasing trend the reduction in precipitation indicated by this reconstruction for the last 150 yr in combination with a significant warming recorded in central chile are the main causes of the observed current glacier retreats

landslides triggered by the 20 april 2013 lushan earthquake sichuan province china abstract the 20 april 2013 lushan earthquake with a magnitude of m s 7 0 induced widespread landsliding along the southern segment of the longmen shan fault zone this paper presents a preliminary analysis of the characteristics of these co seismic landslides triggered in an area of 13 323 km 2 a total of 3810 individual landslide points were identified through an intensive field investigation and from digital aerial photographs taken after the lushan earthquake to facilitate the more detailed analysis on the areal frequency of co seismic landslides as polygons we selected an area of 732 km 2 around the epicenter that had the highest density of co seismic landslides the sizes of the landslides are in general much smaller than those that were triggered by the 2008 wenchuan earthquake the most common types of landslides in the study area were rock falls and shallow disrupted landslides from steep slopes which typically involved the top few meters of weathered bedrock and colluvium in this study the relation between the landslide distribution and five main factors was analyzed fault proximity epicenter proximity peak ground acceleration pga slope angle and lithology our study results show that the landslide concentration tends to decrease with distance from the seismogenic fault and the highest landslide concentration is located within a distance of 5 km regarding the distance to the epicenter the largest landslide density is found at a distance between 5 and 10 km the landslide concentration also increases with increasing slope angle until a maximum for the slope class 45 55 in addition results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the most susceptible to co seismic landslides in this study we found that the location of the hanging wall and the footwall of the fault did not seem to have an important effect on the landslide distribution this is in contradiction to what has been reported in other earthquake areas such as the wenchuan area

the new remote sensing derived swiss glacier inventory i methods a new swiss glacier inventory is to be compiled from satellite data for the year 2000 the study presented here describes two major tasks 1 an accuracy assessment of different methods for glacier classification with landsat thematic mapper tm data and a digital elevation model dem 2 the geographical information system gis based methods for automatic extraction of individual glaciers from classified satellite data and the computation of three dimensional glacier parameters such as minimum maximum and median elevation or slope and orientation by fusion with a dem first results obtained by these methods are presented in part ii of this paper kaab and others 2002 thresholding of a ratio image from tm4 and tm5 reveals the best suited glacier map the computation of glacier parameters in a gis environment is efficient and suitable for worldwide application the methods developed contribute to the u s geological survey led global land ice measurements from space glims project which is currently compiling a global inventory of land ice masses within the framework of global glacier monitoring haeberli and others 2000

source complexity of the 1987 whittier narrows california earthquake from the inversion of strong motion records strong motion records for the whittier narrows earthquake are inverted to obtain the history of slip both constant rupture velocity models and variable rupture velocity models are considered the results show a complex rupture process within a relatively small source volume with at least four separate concentrations of slip two sources are associated with the hypocenter the larger having a slip of 55 90 cm depending on the rupture model these sources have a radius of approximately 2 3 km and are ringed by a region of reduced slip the aftershocks fall within this low slip annulus other sources with slips from 40 to 70 cm each ring the central source region and the aftershock pattern all the sources are predominantly thrust although some minor right lateral strike slip motion is seen the overall dimensions of the whittier earthquake from the strong notion inversions is 10 km long along the strike and 6 km wide down the dip the preferred dip is 30 degree and the preferred average rupture velocity is 2 5 km s moment estimates range from 7 4 to 10 0 times 10 sup 24 dyn cm depending on the rupture model

centreline and cross glacier air temperature variability on an alpine glacier assessing temperature distribution methods and their influence on melt model calculations the spatio temporal distribution of air temperature over mountain glaciers can demonstrate complex patterns yet it is often represented simplistically using linear vertical temperature gradients vtgs extrapolated from off glacier locations we analyse a network of centreline and lateral air temperature observations at tsanteleina glacier italy during summer 2015 on average vtgs are steep 1 but they are shallow under warm ambient conditions when the correlation between air temperature and elevation becomes weaker published along flowline temperature distribution methods explain centreline observations well including warming on the lower glacier tongue but cannot estimate lateral temperature variability application of temperature distribution methods improves simulation of melt rates rmse in an energy balance model by up to 36 compared to the environmental lapse rate extrapolated from an off glacier station however results suggest that model parameters are not easily transferable to glaciers with a small fetch without recalibration such methods have potential to improve estimates of temperature across a glacier but their parameter transferability should be further linked to the glacier and atmospheric characteristics furthermore cold spots which can be 2 c cooler than expected for their elevation whose occurrence is not predicted by the temperature distribution models are identified at one quarter of the measurement sites

shaking intensity thresholds for rock falls and slides evidence from 1987 whittier narrows and superstition hills earthquake strong motion records due to inconsistencies in using descriptive intensity scales to describe earthquake shaking necessary to trigger landslides arias intensity a quantity calculated from seismic strong motion records has been employed as a measure of the seismic energy required to initiate landslides because arias intensity is defined as the sum of all the squared acceleration values from a strong motion record it is a measure of the energy dissipated at a site by shaking it incorporates both amplitude and duration information making it more useful to compare with the failure of slopes than parameters such as peak acceleration arias intensities calculated from the 24 october 1987 superstition hills and the 1 october 1987 whittier narrows earthquakes in southern california allow comparisons with the limits of landslides specifically falls and slides from rock and soil in these two earthquakes these comparisons establish two shaking thresholds for the limits of falls and slides a range of 0 08 to 0 6 m sec is observed for tertiary and younger deposits while the range of 0 01 to 0 07 m sec is observed for mesozoic and older rocks these two ranges of shaking levels are controlled by the relative degree of fracturing and aperture of fracture systems within the two general age groups of rocks and soils in the los angeles area and the imperial valley

dendrogeomorphic dating of rockfalls on low latitude high elevation slopes rodadero iztaccihuatl volcano mexico dynamics and rates of rockfalls have been repeatedly studied in mountain environments with archival records as well as lichenometric radiocarbon or dendrogeomorphic approaches in this study we test the potential of conifers growing at a low latitude high elevation site as a dendrogeomorphic tool to reconstruct to calendar dates associated rockfall activity analysis is based on tree ring records of mexican mountain pine pinus hartwegii lindl growing at timberline 4000 m above sea level a s l and at the runout fringe of a north northeast nne facing slope of the dormant iztaccihuatl volcano mexico which is subject to frequent rockfalls the potential and limitations of tree ring data are demonstrated based on 67 rockfall impacts dated in the increment ring series of 24 trees since ad 1836 while findings of this paper are site specific the study clearly shows the potential of dendrogeomorphic approaches in extra alpine low latitude environments and for the understanding of rockfall processes in space and time copyright 2011 john wiley sons ltd

examining the effects of ground motion and rock strength on the size of boulders falling from an overhanging cliff the presence of boulders a result of rockfall events at the foot of cliffs testifies for a mass wasting process which is widely observed and is often considered to be triggered by earthquakes here we investigate boulders under an overhanging cliff with an emphasis on the principal factors that control boulder size we used a conceptual cantilever beam model to predict the expected maximum length of the overhanging cliff we then compared these calculated lengths to those of the field observed boulders and the length of the overhanging cliff ledge our observations show that the actual lengths of the boulders and overhanging cliff are much shorter than expected from the model as the study area is located in a tectonically active region we first suggested solving this discrepancy by adding the possible effect of ground motion on the size of a boulder detailed pseudo static and dynamic analysis of the effect of earthquakes on the failure of rock beams shows that boulder length may not significantly be shortened by induced ground motions we therefore conclude that strong earthquakes although triggering rockfalls are not expected to control the resultant size of the boulders found at the base of overhanging cliffs we alternatively suggest that the maximum length of a boulder is strongly controlled by the rock strength we conclude that the maximum boulder size that may fall during an earthquake event can be predicted by calculating the cantilever critical length including the effect of the rock size on its tensile strength this together with the measured rock discontinuities in an overhanging cliff suggests an upper bound for the volume of the falling boulders a crucial factor in assessing rockfall hazards

comparison of satellite derived with ground based measurements of the fluctuations of the margins of vatnajokull iceland 1973 92 vatnajokull iceland is the earth s most studied ice cap and represents a classical glaciological field site on the basis of s palsson s seminal glaciological field research in the late 18th century since the 19th century vatnajokull has been the focus of an array of glaciological studies by scientists from many nations including many remote sensing investigations since 1951 landsat derived positions of the termini of 11 outlet glaciers of vatnajokull were compared with frontal positions of six of these 11 outlet glaciers determined by field observations during the period 1973 92 the largest changes during the 19 year period 1973 92 occurred in the large lobate surge type outlet glaciers along the southwestern western and northern margins of vatnajokull tungnaarjokull receded 1413 112 m 1380 1 m from ground observations and bruarjokull receded 1975 191 m 2096 5 m from extrapolated ground observations between 1973 and 1992 satellite images can be used to delineate glacier margin changes on a time lapse basis if the glacier margin can be spectrally discriminated from terminal moraines and sandur deposits and if the advance recession is larger than maximum image pixel size local knowledge of glaciers is critically important however in the accurate delineation of glacier margins on landsat images

an approach to time probabilistic evaluation of seismically induced landslide hazard the need for effective strategies for preventing and mitigating damage caused by earthquake induced landslides has stimulated recent developments of techniques for the assessment of seismic landslide exposure at a regional scale however for a rational risk management a crucial element is represented by the time horizon of the hazardous events a new way to incorporate the time factor in seismic landslide hazard assessment is proposed here it consists of evaluating the temporal recurrence of seismically induced slope failure conditions inferred from the newmark s model first by adopting arias intensity to quantify seismic shaking well established methods of seismic hazard assessment are employed to obtain the occurrence probabilities for different levels of seismic shaking in a time interval of interest then some empirical relations based on the newmark s model are employed to evaluate the slope critical acceleration a c for which a prefixed probability exists that seismic shaking would result in landslide triggering the obtained a c values represent the minimum slope resistance required to keep the probability of seismic landslide triggering within the prefixed value therefore the space distribution of the calculated a c values can be promptly compared with the actual in situ a c values of specific slopes to estimate whether these slopes have a significant probability of failing under seismic action in the future an example of this approach applied to an area in southern italy daunia region shows that the introduction of the time factor significantly modifies the representation of the spatial hazard and allows evaluation of the relevance of seismicity as a landslide triggering agent

on the applicability of available regression models for estimating newmark displacements for low to moderate magnitude earthquakes the case of the betic cordillera s spain abstract newmark displacement estimation is generally computed using empirical models these models are estimated from large datasets that mainly comprise moderate to high magnitude events mw 6 0 in this work we study the performance of several of these models to study moderate to low magnitude scenarios for this purpose data from the betic cordillera s spain with magnitudes ranging from mw 3 5 to 6 3 were used to compare with model predictions the results show that errors in the estimates depend on the magnitude of events or on the yielding acceleration considered to estimate the displacement the availability of an appropriate range of data magnitude and yielding acceleration when defining the regression model may overcome the differences due to specific characteristics of the seismotectonic context of the area where data derives from the results also show that performance of models including several ground motion predictors is better than those based on a single parameter regardless of the combination these predictors furthermore regression models with polynomial forms present a better performance than other functions based on the logarithm of these predictors finally new specific models for the betic cordillera are proposed especially suitable for low magnitude events

the 1987 whittier narrows earthquake sequence in los angeles southern california seismological and tectonic analysis the october 1 1987 whittier narrows earthquake m l 5 9 was located at 34 2 96 n 118 4 86 w at a depth of 14 6 0 5 km in the northeastern los angeles basin the focal mechanism of the mainshock derived from first motion polarities shows pure thrust motion on west striking nodal planes with dips of 25 5 and 65 5 respectively the aftershocks define an approximately circular surface that dips gently to the north centered at the hypocenter of the mainshock with a diameter of 4 6 km hence the spatial distribution of the mainshock and aftershocks as well as the focal mechanisms of the mainshock indicate that the causative fault was a 25 north dipping thrust fault striking west and is confined to depths from 10 to 16 km although most of the 59 aftershock focal mechanisms presented here document a complex sequence of faulting they are consistent with deformation of the hanging wall caused by the thrust faulting observed in the mainshock a cluster of reverse faulting events on north striking planes occurred within hours after the mainshock 2 km to the west of the mainshock the largest aftershock m l 5 3 occurred on october 4 and showed mostly right lateral faulting on the same north northwest striking plane within the hanging wall similarly several left lateral focal mechanisms are observed near the eastern edge of the mainshock rupture the earthquake and calibration blast arrival time data were inverted to obtain two refined crustal velocity models and a set of station delays when relocating the blast using the new models and delays the absolute hypocentral location bias is less than 0 5 km the mainshock was followed by nearly 500 locatable aftershocks which is a small number of aftershocks for this magnitude mainshock the decay rate of aftershock occurrences with time was fast while the b value was low 0 67 0 05 for a los angeles basin sequence

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

the benner pass rock avalanche cluster suggests a close relation between long term slope deformation dsgsds and translational rock slides and catastrophic failure abstract in mountain ranges deep seated gravitational slope deformations dsgsds and extremely rapid mass wastings of rock 105 m3 in volume catastrophic rock slope failures crf are present yet their mutual relation is poorly documented near the brenner pass 1370 m asl in the eastern alps five catastrophic rock slope failures of medium to high grade metamorphites are clustered brenner pass cluster bpc and three of them are related to dsgsds the catastrophic rock slope failures involved volumes from 12 to 110 mm3 and show fahrboeschung angles of 10 27 numerical dating 14c 234u 230th suggests that all catastrophic slope failures of the bpc occurred between 13 5 and 6 2 ka three of the crf events may have occurred during the younger dryas 12 7 11 7 ka whereas two events occurred during the holocene backwater basins dammed up by the crfs range from 2 5 km2 ridnaun rock avalanche to 15 5 km2 stilfes rock avalanche three of the catastrophic rock slope failures are associated with and developed as a partial failure of a dsgsd this suggests that progressively slow deformation of slopes ultimately exceeded a stability threshold resulting in catastrophic rock slope failures the initial kinematic mechanisms of failure vary between large scale toppling wedge sliding and planar sliding and are strongly controlled by the structural setting of the slopes a direct connection of catastrophic mass wasting with specific palaeoclimatic conditions e g phases of enhanced precipitation is not indicated however this does not exclude specific meteorological situations e g occurrence of short term heavy rainfall that may have expedited slope instability and perhaps even triggered catastrophic events attempts to correlate catastrophic rock slope failures with specific palaeoclimatic regimes are still encumbered by substantial methodical uncertainties and imprecisions as well as the scarcity of dated crf events the mapped distribution of crfs unequivocally indicates that structural predisposition is the most significant long term control in forming crf clusters

a semi empirical swell prediction model formulated from clay mineralogy and unsaturated soil properties abstract swell behavior of expansive clays is an inherent property that can be better explained through its hydro mechanical volume change behavior arising from soil attributes like matric suction and clay mineralogy information previous swell related modeling studies have not incorporated these attributes for swell behavior thereby leading to poor to erroneous characterization practices both chemical and hydrological attributes of the soils are targeted in this expansive soil modeling eight natural expansive soils were collected and their swell strains were measured under different confining pressure conditions soil suction properties of expansive soils as well as soil water characteristic curves swcc s were determined using standard measurement procedures including pressure plate and filter paper techniques slope of the paths traversed by the soil specimens in a void ratio soil matric suction framework are determined and used as mechanical input parameters for the heave modeling a new parameter mechanical hydro chemical parameter mhcp is used that accounts for both matric suction and clay mineralogy information this parameter is correlated with swell property measurements and the correlations developed provided reliable and reasonable swell property predictions independent validations with other soils are still needed for further enhancement of the mhcp framework for more reliable predictions

statistical seismic landslide hazard analysis an example from taiwan abstract following the work of lee et al 2008a a statistical approach is applied to seismic landslide hazard analysis for the whole of taiwan all the work is done using new data sets which include a new and carefully mapped chi chi earthquake induced landslide inventory a 5 m dem and a new version of the 1 50 000 scale geologic map of taiwan landslide causative factors used in the susceptibility analysis include the slope gradient slope aspect terrain roughness slope roughness total curvature total slope height and lithology the corrected arias intensity taking topographic amplification into consideration is used as a triggering factor firstly a susceptibility model is built using the 1999 chi chi shallow landslides as a training data set and multivariate logistic regression as the analytical tool this model is validated by using the 1998 jueili earthquake induced landslide data then a probability of failure curve is established by comparing the chi chi landslide data and the susceptibility values after which the spatial probability of landslide occurrence is drawn the temporal probability may be accounted for with the triggering factor the hazard level of the arias intensity which was obtained through regular probabilistic seismic hazard analysis finally the susceptibility model and the probability of failure curve are applied to the whole of taiwan using the topographically corrected 475 year arias intensity as a triggering factor to complete a seismic shallow landslide probability map for ground motions having a 475 year return period

two decades of glacier mass loss along the andes andean glaciers are among the fastest shrinking and largest contributors to sea level rise on earth they also represent crucial water resources in many tropical and semi arid mountain catchments yet the magnitude of the recent ice loss is still debated here we present andean glacier mass changes from 10 n to 56 s between 2000 and 2018 using time series of digital elevation models derived from aster stereo images the total mass change over this period was 22 9 5 9 gt yr 1 0 72 0 22 m w e yr 1 m w e metres of water equivalent with the most negative mass balances in the patagonian andes 0 78 0 25 m w e yr 1 and the tropical andes 0 42 0 24 m w e yr 1 compared to relatively moderate losses 0 28 0 18 m w e yr 1 in the dry andes subperiod analysis 2000 2009 versus 2009 2018 revealed a steady mass loss in the tropics and south of 45 s conversely a shift from a slightly positive to a strongly negative mass balance was measured between 26 and 45 s in the latter region the drastic glacier loss in recent years coincides with the extremely dry conditions since 2010 and partially helped to mitigate the negative hydrological impacts of this severe and sustained drought these results provide a comprehensive high resolution and multidecadal data set of recent andes wide glacier mass changes that constitutes a relevant basis for the calibration and validation of hydrological and glaciological models intended to project future glacier changes and their hydrological impacts glaciers in the andes have lost about 23 gt of mass per year between 2000 and 2018 with the fastest loss in patagonia according to time series of digital elevation models that are based on aster stereo images

3d pore analysis of sedimentary rocks abstract a 3d representation of the internal structure and fabric of sedimentary rocks is of paramount interest to evaluate their structural parameters such as porosity pore size distribution and permeability the classical experimental technique to evaluate the pore space volume and pore size distribution is the mercury intrusion porosimetry mip computer based methods use 3d imaging technologies such as computer tomography ct scanned images to construct and evaluate a 3d virtual representation of the internal pore distribution in this work based on a three samples set of sandstone we apply two numerical computer based methods in order to reconstruct and analyse the internal pore network and compare it with the results obtained by mip analysis the first numerical method performs a virtual simulation of mip the second one obtains a graph of pores using a sphere filling based approach for all methods we compute the global porosity and the pore size distribution moreover with the numerical methods we obtain the total porosity and a graph representing the pore space that can be visualized with 3d illustration techniques