regionally differentiated contribution of mountain glaciers and ice caps to future sea level rise the contribution to sea level rise from mountain glaciers and ice caps has grown over the past decades a projection of their melting during the twenty first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21 of their total global volume

on the characterization of glacier response by a single time scale glacier response to climate can be characterized by a single time scale when the glacier changes sufficiently slowly then the derivative of volume with respect to area defines a thickness scale similar to that of johannesson and others and the time scale follows from it our version of the time scale is different from theirs because it explicitly includes the effect of surface elevation on mass balance rate which can cause a major increase in the time scale or even lead to unstable response the time constant has a dual role controlling both the rate and magnitude of response to a given climate change data from south cascade glacier washington u s a illustrate the ideas some of the difficulty in obtaining accurate values for the thickness and time scales and the susceptibility of all response models to potentially large errors

flow dissolution and precipitation in dolomite 1 the evolution of hydraulic conductivity and porosity during the process of dedolomitization was examined in a series of laboratory experiments by analyzing the effects of concurrent dolomite dissolution and calcium carbonate precipitation linear flow experiments were performed in columns of crushed sucrosic dolomite by injecting different concentrations of hcl at various flow rates temporal changes in head gradient were used to calculate overall hydraulic conductivities of each column while chemical analyses of the effluent acid enabled estimation of porosity changes during the experiments after each experiment the rock samples were retrieved and sectioned in order to study the pore space geometry micromorphology and mineral concentrations a range of injected hcl concentrations and flow rates was identified which leads to oscillations in the effective hydraulic conductivity and porosity of the evolving rock samples in all cases however the porous medium ultimately clogged short term experiments were also used to study the formation of dissolution and precipitation bands along the columns under the experimental conditions dolomite dissolution is a reaction rate controlled process experiments indicated that as such the flow rate and the ph of the injected fluid affect dissolution only during the initial stages when calcium carbonate is dissolved on the other hand both the flow rate and the ph of the injected fluid strongly influence the precipitation process throughout the duration of the experiments because higher flow rates retard nucleation these findings are in qualitative accordance with field observations of dolomite formations

dynamics of the 1984 rock avalanche and associated distal debris flow on mount cayley british columbia canada implications for landslide hazard assessment on dissected volcanoes abstract in 1984 a mass of quaternary pyroclastic rock est vol 0 74 106m3 slid from the western flank of mount cayley volcano in southwest british columbia the disintegrating rock mass entrained a further 0 20 106 m3 and formed a rock avalanche that travelled a horizontal distance of 3 46 km from its source over a vertical elevation difference of 1 18 km equivalent to a fahrboschung of 19 from the superelevation of the debris trimline in the mid path it is estimated that velocities reached at least 42 m s in the upper part of its path velocities may have approached 70 m s the rock avalanche was partially transformed into a distal debris flow that travelled a further 2 6 km down turbid creek in a narrow channelised path to the squamish river temporarily blocking it the motion of the rock avalanche including the production of a distal debris flow was successfully simulated using a dynamic analytical model both the results of this analysis and field evidence indicate that the rock avalanche did not come to a halt in the upper part of its path as suggested by cruden and lu 1992 but travelled to its distal limit in one uninterrupted movement this finding has important implications for landslide hazard assessment at mount cayley and similar sites the landslide is typical of those which occur on the steep slopes of dissected volcanoes and is one of seven high velocity rock avalanches that have occurred in the garibaldi volcanic belt of southwest british columbia since 1855

a note on induced stress changes in hydrocarbon and geothermal reservoirs abstract earthquakes have been induced by oil and gas production where pore pressures have decreased in some cases by several tens of mpa it has previously been suggested that such earthquakes are caused by poroelastic stressing of crust surrounding the reservoir induced earthquakes are also common in geothermal fields such as the geysers where strong correlations between both steam production and condensate injection and earthquake activity have been observed over the last several decades stress measurements within hydrocarbon reservoirs show that the least horizontal stress decreases with declining reservoir pressure as predicted by poroelasticity for circular disk shaped reservoirs isothermal reduction in pore pressure induces a relative horizontal tension within the reservoir production induced stressing may promote frictional sliding on pre existing faults within the reservoir itself normal faulting is promoted if the regional stress is extensional and the biot coefficient is sufficiently large 0 85 for reasonable coefficients of friction on the other hand dilatant fracturing and normal faulting are always promoted in extensional environments near the edge of the reservoir or in regions of high pore pressure gradient it is suggested that such fracturing could enhance fracture permeability in tight rocks adjacent to portions of the reservoir that experience large reductions in pore pressure due to production in regional compressional environments production modestly favors reverse faulting above and below the reservoir the ratio of thermal to poroelastic stress can be quite large in geothermal reservoirs such as the geysers reservoir wide energy balance considerations suggest that the average temperature has declined at the geysers by 6 c during the past 20 years reservoir average stress changes are thus on the order of 2 mpa and are certainly much larger near injection wells and steam producing fractures

transient response of idealized glaciers to climate variations the transient response of glaciers to climate variations is investigated with a novel low order model of an idealized glacier resting on uniformly inclined bedrock the model consists of two volumes representing the accumulation and ablation areas which are joined by a flux gate controlling mass flow according to the shallow ice approximation under the assumption of a constant vertical mass balance gradient a volume length scaling relation is derived which depends explicitly on mass balance gradient and bedrock slope analytic expressions for the volume and area timescales are given which are inversely proportional to the mass balance gradient and a geometric factor which is the ratio between the vertical extent of the ablation area and the ice thickness at the equilibrium line from the low order model a dynamical system in length and volume is obtained results from this system are in good agreement with solutions obtained from a transient finite element model solving the full force balance and mass conservation equations under periodic forcing there are significant deviations of the length response which show that the usual relaxation type parameterization of length change is not well suited for short term reactions switching on and off periodic climate forcing the model glaciers show surprisingly large initial and final transient responses that have not been investigated before these results are of significance for the interpretation of length and thickness changes observed on glaciers

the role of rock fragmentation in the motion of large landslides abstract by considering the implications of the comminution generally associated with very large landslides we arrive at a simple explanation for the remarkably low frictional resistance to motion demonstrated by large intact blockslides e g waikaremoana new zealand volcanic debris avalanches e g socompa chile and large rock avalanches e g falling mountain n z which allows such mass movements to achieve unexpectedly high velocities and long runout distances during rapid grain flow under high direct stress the overall grain motion generates stresses in many force chains that strain individual grains to failure most of the elastic strain energy accumulated in these force chains before failure is returned at failure to the resulting grain fragments resulting in apparent instantaneous pressures of 3q on the surroundings where q is the ambient strength of the previously intact grains gpa these intense pressures support some of the direct force on the shear layer so that the effective intergranular stress in the shear layer is reduced because frictional resistance is proportional to effective stress this reduces the overall frictional resistance to shear the steady state effective stress is that which just allows fragmentation to continue the resistance to motion estimated from this relationship explains to much better than order of magnitude accuracy the reported motions of the large rapid mass movements we also deduce that grain fragmentation can be sustained for sufficiently long to explain the phenomena without reducing the mean grain size by volume in the granular layer to unrealistically small values the presence of pore fluid does not appear to influence the effect of fragmentation dynamics in a major way the proposed mechanism requires further laboratory and simulation studies to reduce its current dependence on limited field data but its success suggests that it is worthwhile investigating further as an explanation for large mass movements in the types of brittle rock in which fragmentation occurs

geothermal reservoir modeling in a coupled thermo hydro mechanical chemical approach a review abstract heat extraction from the geothermal reservoir is sensitive to reservoir properties operating parameters and coupling among various processes due to complex reservoir structure heat extraction performances and flow field behaviour in geothermal reservoirs are very different than the small scale laboratory model experiments in recent past significant progress in reservoir scale numerical modeling has been made for quantification of challenges in geothermal energy system development in this paper a comprehensive review of state of the art geothermal reservoir modeling for heat extraction is presented various numerical tools and approaches such as the finite difference method finite element method finite volume method etc to model the geothermal reservoir in the last four decades are discussed the thrust of this paper is on a critical review of individual evaluation of coupling among all possible processes that are thermo hydro mechanical and chemical processes on heat extraction performance future directions in developing better understanding on geothermal reservoir systems are proposed

granular flow experiments on the interaction with stationary runout path materials and comparison to rock avalanche events the central focus of this work is to study the processes acting well below the surface of a moving rock or debris avalanche during travel over stationary substrate material small scale physical models at a linear scale of 1 104 used coal as avalanche analogue material and different granular material simulating sedimentary substrates varying in frictional resistance thickness and relative basal boundary roughness as well as inerodible non deformable runout path conditions substrate materials with the least frictional resistance showed the greatest response to granular flow overriding becoming entirely mobilized beneath and ahead of the moving mass and producing the longest runout observed with a unique deposit profile shape with a smooth substrate basal contact failure occurred along this plane and avalanche and substrate became coupled during runout with a rough base however temporary force chains of grain contacts in the substrate prevailed longer imparted their resistance to motion shear into the granular flow and the flow rear section consequently halted earlier than when moving over substrates with a weak base reducing substrate thickness diminished the effect of basal contact roughness on granular flow runout and deposit length inerodible non deformable substrate conditions caused changes in granular flow behaviour from essentially en masse sliding on low friction surfaces to increasing granular agitation over rougher paths copyright 2012 john wiley sons ltd

interaction between landsliding materials and the underlying erodible bed in a loess flowslide abstract loess landslides exhibit strong interactions with the terrace sediments of the jing river on the south jingyang platform jingyang xi an china analysis of past landslide events revealed that the sand layer of this terrace was thrust up to the surface accompanied by other terrace sediments of carrying this led to the formation of a thrust nappe structure over a long distance we performed ring shear tests to examine the shear behavior of this sand layer with the finding that saturated sand was highly susceptible to liquefaction induced failure the groundwater level of the study area is high resulting in near saturation of the sand layer therefore topographic interferences contributed additional variables and increased interaction complexities simulations indicated that the liquefied sand layer was compressed and forced due to the absence of constraints the sand layer near the bottom of the slope was sheared out over a relatively short distance on the other hand particle interia and constraints of the stable layer resulted in the sand layer near the distal part of the deposits being sheared upward to the ground finally an initiation movement model of loess flowslides is proposed it describes static liquefaction of the loess layer of the slope resulted in occurrence of flowslides collisions between the deposits from the platform edge slope and terrace sediments resulted in the shear liquefaction of sands the landslide experienced four stages as they moved scraping collisions floating scrapes folded thrusts and nappe accumulation

x ray tomography characterization of fracture surfaces during dissolution 1 the changes of fracture surfaces geometry and extend are studied using x ray tomography during aperture increase due to co2 rich fluid percolation dissolution experiments were conducted on two micritic rock samples one pure calcite end member and one with typical composition for marine carbonates 85 calcite high resolution digital images of the fracture geometry allow quantifying the surface properties changes over four spatial scales with a resolution of 4 91 m fracture surfaces are self affine with an initial dimension of 2 5 dissolution of the pure calcite sample is clearly a process of homogeneous chemical erosion of the surface elevation fractal dimension and specific surface remains constant 1 5 times the planar surface conversely for the 85 calcite sample initial topographic surfaces of the fracture walls evolve rapidly toward non topographic interfaces displaying overhangs due the preferential dissolution of the carbonate grains in this case the conventional definition of the effective aperture must be revisited such structures can only be assessed from 3d observations as dissolution progresses the specific surface increases strongly more than 5 times the planar surface and probably faster than the reactive surface

thermal strain in a water saturated limestone under hydrostatic and deviatoric stress states abstract the present study is aimed at investigating the evolution of thermally induced bulk strain in a water saturated limestone blaubeuren at three different stress states three cylindrical rock samples are respectively loaded to a constant stress state 1 3 15 mpa 1 45 mpa 3 15 mpa 1 75 mpa 3 15 mpa at drained conditions in a conventional triaxial rock deformation apparatus before the sample temperature is cycled between 30 c and defined levels up to 120 c strain measurements are performed by one circumferential and two axial extensometers irreversible strain in both the lateral and axial sample directions are measured after each temperature cycle indicating permanent increases in diameter and in length the measured bulk strain is separated into different strain components related to 1 initial stress loading 2 reversible thermal expansion and contraction of rock matrix and 3 some residual strain the magnitudes of the residual strain increase with increasing deviatoric stress 1 3 in the lateral direction but decrease with increasing deviatoric stress in the axial direction the derived matrix thermal expansion coefficients range from 6 10 6 c 1 to 1 8 10 5 c 1 and from 9 10 6 c 1 to 1 5 10 5 c 1 respectively in the axial and lateral directions and present lower values at higher deviatoric stresses microstructural analyses evidence tensile cracks which are interpreted to have been induced during the temperature cycles these cracks have the potential to offset matrix thermal expansion yielding lower matrix thermal expansion coefficients at higher deviatoric stresses

investigating landslide related cracks along the edge of two loess platforms in northwest china cracks are widely developed along the edge of loess platforms in northwest china field surveys reveal that these cracks can be grouped into shallow and deeply penetrating ones the former occur at a small distance from the platform edge normally penetrate into the top unsaturated loess with the penetration depth being controlled by the joints in loess the latter penetrate deeper into the saturated loess farther away from the platform edge these cracks control the inflow and drainage of irrigation water the shallow penetrating crack can fail as a slide or fall with a volume of up to hundreds of cubic meters the deeply penetrating crack can fail as a flow like landslide with a volume of thousands of cubic meters or more a full scale field test simulating irrigation on the platform surface was conducted the two types of crack can be interconnected so that the water applied in the test finally flowed into the deep crack and was discharged from the platform analysis of soil stress states and the results of field test show that the deeply penetrating cracks could have both positive as well as negative effects on slope stability on the one hand water can flow more freely in the cracks and the loess could be saturated and trigger a landslide on the other hand the water can drain more easily along the crack and slope stability could be enhanced as the groundwater level is suppressed copyright 2012 john wiley sons ltd

sea level rise from glaciers and ice caps a lower bound 1 one of the most easily measured dimensions of a glacier the accumulation area is linked to future changes in glacier volume and consequent changes in sea level currently observed accumulation areas are too small forcing glaciers to lose 27 of their volume to attain equilibrium with current climate as a result at least 184 33 mm of sea level rise are necessitated by mass wastage of the world s mountain glaciers and ice caps even if the climate does not continue to warm if the climate continues to warm along current trends a minimum of 373 21 mm of sea level rise over the next 100 years is expected from glaciers and ice caps when compared to recent estimates from all other sources melt water from glaciers must be considered as a particularly important fraction of the total sea level rise expected this century

low sea level rise projections from mountain glaciers and icecaps under global warming the mean sea level has been projected to rise in the 21st century as a result of global warming such projections of sea level change depend on estimated future greenhouse emissions and on differing models but model average results from a mid range scenario a1b suggests a 0 387 m rise by 2100 refs 1 2 the largest contributions to sea level rise are estimated to come from thermal expansion 0 288 m and the melting of mountain glaciers and icecaps 0 106 m with smaller inputs from greenland 0 024 m and antarctica 0 074 m here we apply a melt model and a geometric volume model to our lower estimate of ice volume and assess the contribution of glaciers to sea level rise excluding those in greenland and antarctica we provide the first separate assessment of melt contributions from mountain glaciers and icecaps as well as an improved treatment of volume shrinkage we find that icecaps melt more slowly than mountain glaciers whose area declines rapidly in the 21st century making glaciers a limiting source for ice melt using two climate models we project sea level rise due to melting of mountain glaciers and icecaps to be 0 046 and 0 051 m by 2100 about half that of previous projections

the liquefaction of sands a collapse surface approach recent large scale slides occurring during the hydraulic placement of an artificial island berm in the beaufort sea resulted from the liquefaction of the berm sand subsequent laboratory tests and

synchronization of dissolution and precipitation fronts during infiltration driven replacement in porous rocks coupled dissolution precipitation reactions where two minerals share a common ion occur frequently in geological replacement the reactions are driven by an inflow of precipitating secondary ions and an outflow of dissolved primary ions although crystallization pressure is frequently invoked to explain volume preserving replacement it cannot be operative if the chemical reactions lead to a loss of mineral volume here the host rock that should confine the precipitating mineral is dissolving faster than the grains are growing in this paper we propose two chemical mechanisms by which a rapid dissolution front and a slower precipitation front can be synchronized and volume for volume replacement preserved we analyze these mechanisms within the framework of reactive transport theory and show that morphological features observed in calcite replacement can be correlated with predictions of the models

a macroscopic approach to glacier dynamics a simple approach to glacier dynamics is explored in which there is postulated to be a relationship between area and volume with three parameters the time for area to respond to changes in volume a thickness scale and an area characterizing the condition of the initial stale this approach gives a good fit to the measurements of cumulative balance and area on south cascade glacier from 1970 97 the area time scale is roughly 8 years the thickness scale about 123 m and the 1970 area roughly 4 larger than required for adjustment with volume combining this relationship with a version of mass continuity expressed in terms of area and volume produces a theory of glacier area and volume response to climate in which another time constant the volume time scale appears area and volume both respond like a damped spring and mass system the damping of the south cascade response is approximately critical and the volume time scale is roughly 48 vexes six times the area time scale the critically damped spring and mass analogy reproduces the time dependence predicted by the more complicated traditional theory of nyc

the physical basis of glacier volume area scaling ice volumes are known for only a few of the roughly 160 000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates a scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas the relationship requires four closure choices for the scaling behavior of glacier widths slopes side drag and mass balance reasonable closures predict a volume area scaling exponent which is consistent with observations giving a physical and practical basis for estimating ice volumes glacier volume is insensitive to perturbations in the mass balance scaling but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume

volume area scaling of glaciers and ice caps and their longitudinal profiles empirical data on the volume area scaling of glaciers and ice caps are compared with theoretical models of longitudinal glacier profiles ice caps are described well by theoretical solutions of the differential equations modeling longitudinal profiles but glaciers for which the surface slope is approximated by the ice thickness divided by the length are not a power law profile recently derived analytically reproduces exactly the thickness length scaling first predicted by scaling analysis for ice caps

ice volume and subglacial topography for western canadian glaciers from mass balance fields thinning rates and a bed stress model abstracta method is described to estimate the thickness of glacier ice using information derived from the measured ice extent surface topography surface mass balance and rate of thinning or thickening of the ice column shear stress beneath an ice column is assumed to be simply related to ice thickness and surface slope as for an inclined slab but this calculation is cast as a linear optimization problem so that a smoothness regularization can be applied assignment of bed stress is based on the flow law for ice and a mass balance calculation but must be preceded by delineation of the ice flow drainage basin validation of the method is accomplished by comparing thickness estimates to the known thickness generated by a numerical ice dynamics model once validated the method is used to estimate the subglacial topography for all glaciers in western canada that lie south of 60 n adding the present ice volume of each glacier gives the estimated total volume as 2320 km3 equivalent to 5 8 mm of sea leve

thermo poroelastic numerical modelling for enhanced geothermal system performance case study of the gros schonebeck reservoir abstract significant pressure and temperature changes can occur within geothermal reservoirs caused by injection and production of fluid which can affect transport properties of the rocks and therefore alter reservoir performance and sustainability to understand the coupling between transport properties evolution and state variable changes a complete description of the mechanical behavior of the reservoir is required which should consider thermo and poroelastic effects this study aims to integrate transport properties evolution for coupled thermo hydro mechanical thm process modelling of fluid bearing reservoirs this approach is here applied to the geothermal research site of gros schonebeck 40 km north of berlin germany which consists of a doublet system at a target depth of about 4100 m in which both injection and production wells have been hydraulically stimulated a 3d reservoir model including the main geological units major natural fault zones and hydraulic fractures is integrated in the finite element method based simulator opengeosys for modelling coupled thm processes during geothermal activity one challenge of this study is to integrate both hydro geological and physical complexity to better describe the dynamic behavior of the geothermal reservoir from the results of the simulation thermal breakthrough is observed after 18 years of injection and life time of the system has been evaluated as 50 years furthermore a 5 5 increase of porosity around the injection well is observed as well as an increase of the anisotropy ratio for permeability k z k xy of about 2 these transport properties enhancements lead to a decrease of the thermal breakthrough time around 8 and life time of the system 14 compared to classic thermo hydro simulations with constant transport properties the results presented here provide therefore valuable insights for understanding porosity and permeability distributions and evolutions during injection and production of geothermal fluids and related impacts on reservoir performance

modelling of fractured carbonate reservoirs outline of a novel technique via a case study from the molasse basin southern bavaria germany fluid flow in low permeable carbonate rocks depends on the density of fractures their interconnectivity and on the formation of fault damage zones the present day stress field influences the aperture hence the transmissivity of fractures whereas paleostress fields are responsible for the formation of faults and fractures in low permeable reservoir rocks fault zones belong to the major targets before drilling an estimate for reservoir productivity of wells drilled into the damage zone of faults is therefore required due to limitations in available data a characterization of such reservoirs usually relies on the use of numerical techniques the requirements of these mathematical models encompass a full integration of the actual fault geometry comprising the dimension of the fault damage zone and of the fault core and the individual population with properties of fault zones in the hanging and foot wall and the host rock the paper presents both the technical approach to develop such a model and the property definition of heterogeneous fault zones and host rock with respect to the current stress field the case study describes a deep geothermal reservoir in the western central molasse basin in southern bavaria germany results from numerical simulations indicate that the well productivity can be enhanced along compressional fault zones if the interconnectivity of fractures is lateral caused by crossing synthetic and antithetic fractures the model allows a deeper understanding of production tests and reservoir properties of faulted rocks

field testing of irrigation effects on the stability of a cliff edge in loess north west china as it is not uncommon that irrigation has triggered landslides in the chinese loess plateau a full scale field testing in a typical cracked plateau in heifangtai gansu province of china to simulate such phenomenon was conducted in the study piezometers were installed to measure the groundwater and crackmeters as well as inclinometers were used to measure the slope movement water was pumped from the nearby source daily to simulate the irrigation process there was a sharp increase of pore pressure in the undisturbed loess below the crack when the inclinometer registered considerable movement due to the inflow of water via the crack such increase in pore pressure also dissipated rapidly eventually the irrigation water daylighted at the major cracks from the face of the plateau leading to local failures the results show that cracks have significant effects on the flow of the irrigation water into the ground the rapid rise in the local pore water pressure had reduced the stability of the slope

glacier volume area relation for high order mechanics and transient glacier states 1 glacier volume is known for less than 0 1 of the world s glaciers but this information is needed to quantify the impacts of glacier changes on global sea level and regional water resources observations indicate a power law relation between glacier area and volume with an exponent 1 36 through numerical simulations of 3d high order glacier mechanics we demonstrate how different topographic and climatic settings glacier flow dynamics and the degree of disequilibrium with climate systematically affect the volume area relation we recommend more accurate scaling relations through characterization of individual glacier shape slope and size an ensemble of 280 randomly generated valley glaciers spanning a spectrum of plausible glaciological conditions yields a steady state exponent 1 46 this declines to 1 38 for glaciers that are 100 years into a sustained retreat which corresponds exceptionally well with the observed value for present day glaciers

crossover scaling phenomena for glaciers and ice caps while the terms glacier and ice cap have distinct morphological meanings no easily defined boundary or transition distinguishes one from the other despite this the exponent of the power law function relating volume to surface area differs sharply for glaciers and ice caps suggesting a fundamental distinction beyond a smoothly transitioning morphology a standard percolation technique from statistical physics is used to show that valley glaciers are in fact differentiated from ice caps by an abrupt geometric transition the crossover is a function of increasing glacier thickness but it owes its existence more to the nature of the underlying bedrock topography than to specifics of glacier mechanics the crossover is caused by a switch from directed flow that is constrained by surrounding bedrock topography to unconstrained radial flow of thicker ice that has subsumed the topography the crossover phenomenon is nonlinear and rapid so that few if any glaciers will have geometries or dynamics that blend the two extremes the exponents of scaling relationships change abruptly at the crossover from one regime to another in particular the volume area scaling exponent will switch from 1 375 for glaciers to 1 25 for ice caps with few if any ice bodies having exponents that fall between these values

occurrence of landsliding on slopes where flowsliding had previously occurred an investigation in a loess platform north west china abstract loess slides in south jingyang platform shaanxi province usually occur on slopes where loess flowslides had previously occurred numerical modeling shows that flowslide occurrence causes conditions that increase shear stress and water content in the subsequent slopes both of these factors move the soil stress states towards its theoretical failure line under these conditions only small increases in water content can cause soil collapse this leads to the backscarps of former flowslides being much more prone to landsliding wetting test results show that the loess can collapse suddenly as the water content gradually increases therefore the wetting process induced by continued irrigation may result in the subsequent slides during constant water content tests of the loess material soil shear strength increases with the development of specimen deformation therefore slide mobilization which may be a relatively slow process is dependent on whether the wetting conditions exist finally a slope evolution model for loess platforms is proposed in this study

reactive transport modeling in fractured rock a state of the science review abstract the field of reactive transport modeling has expanded significantly in the past two decades and has assisted in resolving many issues in earth sciences numerical models allow for detailed examination of coupled transport and reactions or more general investigation of controlling processes over geologic time scales reactive transport models serve to provide guidance in field data collection and in particular enable researchers to link modeling and hydrogeochemical studies in this state of science review the key objectives were to examine the applicability of reactive transport codes for exploring issues of redox stability to depths of several hundreds of meters in sparsely fractured crystalline rock with a focus on the canadian shield setting a conceptual model of oxygen ingress and redox buffering within a shield environment at time and space scales relevant to nuclear waste repository performance is developed through a review of previous research this conceptual model describes geochemical and biological processes and mechanisms materially important to understanding redox buffering capacity and radionuclide mobility in the far field consistent with this model reactive transport codes should ideally be capable of simulating the effects of changing recharge water compositions as a result of long term climate change and fracture matrix interactions that may govern water rock interaction other aspects influencing the suitability of reactive transport codes include the treatment of various reaction and transport time scales the ability to apply equilibrium or kinetic formulations simultaneously the need to capture feedback between water rock interactions and porosity permeability changes and the representation of fractured crystalline rock environments as discrete fracture or dual continuum media a review of modern multicomponent reactive transport codes indicates a relatively high level of maturity within the yucca mountain nuclear waste disposal program reactive transport codes of varying complexity have been applied to investigate the migration of radionuclides and the geochemical evolution of host rock around the planned disposal facility through appropriate near and far field application of dual continuum codes this example demonstrates how reactive transport models have been applied to assist in constraining historic water infiltration rates interpreting the sealing of flow paths due to mineral precipitation and investigating post closure geochemical monitoring strategies natural analogue modeling studies although few in number are also of key importance as they allow the comparison of model results with hydrogeochemical and paleohydrogeological data over geologic time scales

landslide mobility and hazards implications of the 2014 oso disaster abstract landslides reflect landscape instability that evolves over meteorological and geological timescales and they also pose threats to people property and the environment the severity of these threats depends largely on landslide speed and travel distance which are collectively described as landslide mobility to investigate causes and effects of mobility we focus on a disastrous landslide that occurred on 22 march 2014 near oso washington usa following a long period of abnormally wet weather the landslide s impacts were severe because its mobility exceeded that of prior historical landslides at the site and also exceeded that of comparable landslides elsewhere the 8 10 6 m 3 landslide originated on a gently sloping

thermal hydrologic mechanical chemical processes in the evolution of engineered geothermal reservoirs abstract in a companion paper taron j elsworth d min k b numerical simulation of thermal hydrologic mechanical chemical processes in deformable fractured porous media int j rock mech min sci 2009 doi 10 1016 j ijrmms 2009 01 008 we introduced a new methodology and numerical simulator for the modeling of thermal hydrologic mechanical chemical processes in dual porosity media in this paper we utilize the model to examine some of the dominant behaviors and permeability altering mechanisms that may operate in naturally fractured media permeability and porosity are modified as fracture apertures dilate or contract under the influence of pressure solution thermo hydro mechanical compaction dilation and mineral precipitation dissolution we examine a prototypical enhanced geothermal system egs for the relative temporal arrival of hydro mechanical vs thermo mechanical vs chemical changes in fluid transmission as cold 70 c water is injected at geochemical disequilibrium within a heated reservoir 275 c for an injection withdrawal doublet separated by 670 m the results demonstrate the strong influence of mechanical effects in the short term several days the influence of thermal effects in the intermediate term 1 year influence of chemical effects especially close to injection in most of the reservoir cooling enhances permeability and increases fluid circulation under pressure drive we observe thermo mechanical driven permeability enhancement in front of the advancing thermal sweep counteracted by the re precipitation of minerals previously dissolved into the cool injection water near injection calcite dissolution is capable of increasing permeability by nearly an order of magnitude while precipitation of amorphous silica onsets more slowly and can completely counteract this increase over the very long term 10 years for the reinjection of highly silica saturated water amorphous silica is capable of drastic reduction in permeability close to the injection well with combined action from all mechanisms permeability change varies by two orders of magnitude between injection and withdrawal

time scale for adjustment of glaciers to changes in mass balance the length of time tm over which a glacier responds to a prior change in climate is investigated with reference to the linearized theory of kinematic waves and to results from numerical models we show the following tm may in general be estimated by a volume time scale describing the time required for a step change in mass balance to supply the volume difference between the initial and final steady states the factor f in the classical estimate of m l u where i is glacier length and u is terminus velocity has a simple geometrical interpretation ft is the ratio of thickness change averaged over the full length i to the change at the terminus although both u and f relate to dynamic processes local to the terminus zone the ratio f u and therefore tm are insensitive to details of the terminus dynamics in contrast to conclusions derived from some simplified kinematic wave models a more robust estimate of tm independent of terminus dynamics is given by tm h b where h is a thickness scale for the glacier and b is the mass balance rate negative at the terminus we suggest that tm for mountain glaciers can be substantially less than the 1o2 103 years commonly considered to be theoretically expected

using the surface profiles of modern ice masses to inform palaeo glacier reconstructions abstract morphometric study of modern ice masses is useful because many reconstructions of glaciers traditionally draw on their shape for guidance here we analyse data derived from the surface profiles of 200 modern ice masses valley glaciers icefields ice caps and ice sheets with length scales from 100 to 103 km from different parts of the world four profile attributes are investigated relief span and two parameters c and c that result from using nye s 1952 theoretical parabola as a profile descriptor c and c respectively measure each profile s aspect ratio and steepness and are found to decrease in size and variability with span this dependence quantifies the competing influences of unconstrained spreading behaviour of ice flow and bed topography on the profile shape of ice masses which becomes more parabolic as span increases with c and c tending to low values of 2 5 3 3 m1 2 the same data reveal coherent minimum bounds in c and c for modern ice masses that we develop into two new methods of palaeo glacier reconstruction in the first method glacial limits are known from moraines and the bounds are used to constrain the lowest palaeo ice surface consistent with modern profiles we give an example of applying this method over a three dimensional glacial landscape in kamchatka in the second method we test the plausibility of existing reconstructions by comparing their c and c against the modern minimum bounds of the 86 published palaeo ice masses that we put to this test 88 are found to be plausible the search for other morphometric constraints will help us formalise glacier reconstructions and reduce their uncertainty and subjectiveness

liquefaction and flow failure during earthquakes two aspects of seismically induced liquefaction are discussed which are of vital engineering significance the triggering condition and the consequences of liquefaction the triggering condition is examined with respect to liquefaction analysis note being taken of the onset condition which is governed by cyclic strength consequences of liquefaction are discussed with respect to post seismic stability analysis in which the residual strength plays a major role procedures used for liquefaction analysis based on the results of in situ sounding tests are introduced and the applicability of this method for estimating associated ground settlements is discussed the evaluation of residual strength requires a better understanding of undrained sand behaviour results of extensive laboratory rests on japanese standard sand are examined and new index parameters are proposed to quantify undrained sand behaviour better the results of laboratory tests on silty sands are examined in the same way ah the results are

glaciers dominate eustatic sea level rise in the 21st century ice loss to the sea currently accounts for virtually all of the sea level rise that is not attributable to ocean warming and about 60 of the ice loss is from glaciers and ice caps rather than from the two ice sheets the contribution of these smaller glaciers has accelerated over the past decade in part due to marked thinning and retreat of marine terminating glaciers associated with a dynamic instability that is generally not considered in mass balance and climate modeling this acceleration of glacier melt may cause 0 1 to 0 25 meter of additional sea level rise by 2100