4 d imaging of subsurface changes with coda waves numerical studies of 3 d combined sensitivity kernels and applications to the m_ mathrm w m w 7 9 2008 wenchuan earthquake in the context of seismic monitoring recent studies made successful use of seismic coda waves to image the lateral extent of medium changes locating the depth of the changes however remains a challenge we use multiply scattered body and surface wave 3 d combined sensitivity kernels to address this problem we show that we can locate velocity perturbations at depth with numerical data from elastic wave field simulations in 3 d heterogeneous media this procedure is then applied to assess the extent of the crustal damage due to the m mathrm w 7 9 2008 wenchuan earthquake we discuss the potential and limitations of our approach to retrieve the depth information of temporal changes occurring in heterogeneous structures

train traffic as a powerful noise source for monitoring active faults with seismic interferometry laboratory experiments report that detectable seismic velocity changes should occur in the vicinity of fault zones prior to earthquakes however operating permanent active seismic sources to monitor natural faults at seismogenic depth is found to be nearly impossible to achieve we show that seismic noise generated by vehicle traffic and especially heavy freight trains can be turned into a powerful repetitive seismic source to continuously probe the earth s crust at a few kilometers depth results of an exploratory seismic experiment in southern california demonstrate that correlations of train generated seismic signals allow daily reconstruction of direct p body waves probing the san jacinto fault down to 4 km depth this new approach may facilitate monitoring most of the san andreas fault system using the railway and highway network of california

a rudimentary mechanistic model for soil production and landscape development a rudimentary mechanistic model for soil production and landscape development is proposed the continuity equation of the model assumes that the change in soil thickness over time depends on the production of soil from the weathering of bedrock and the transport of soil through natural surface erosion the parameters for the model include the weathering rate and erosive diffusivity weathering rate is expressed as an exponential decay function of soil thickness which represents mechanical weathering erosive diffusivity can be estimated from soil erosion models the model is solved numerically using the finite difference approach and is applied to a numerical example simulation is performed for a hypothetical landscape with a series of hills and valleys results show the development rate of soil initially is very large and slows down until it reaches a steady state defined by a constant change in soil thickness the model also exhibits the characteristics of a nonlinear dynamic system nonlinearity of soil thickness and curvature and initial randomness appears to cause chaos instability in the system the results show promising progress in quantitative modelling of pedogenesis the limitations and suggested improvements of the model are also presented

inversion of fluvial channels for paleorock uplift rates in taiwan the transient response of erosion to changes in rock uplift rate leads to the preservation of rock uplift history in the long profiles of rivers however extracting this information is nontrivial as changes in channel steepness are the result of both spatial and temporal changes in rock uplift rate as well as other factors such as climate and rock type we exploit an analytical linear solution for river channel profile evolution in response to erosion and tectonic uplift to investigate the rock uplift history of taiwan the analytical approach allows us to solve the linear inverse problem efficiently extracting rock uplift as a function of space and time from digital elevation data we assess the potential of fluvial topography to resolve rock uplift rates using three approaches 1 a synthetic resolution test 2 analysis of the forward model to demonstrate where in space and time the fluvial topography constrains rock uplift rate and 3 interpretation of the model resolution matrix furthermore the potential to analyze large data sets reduces the influence of stochastic processes such as landslides small scale river network reorganization and also local lithological variability in taiwan our analysis suggests that current rock uplift rates exceed erosion rates across much of the island and that there has been an increase in rock uplift rates since 0 5 ma across the central range

mechanistic soil landscape modelling as an approach to developing pedogenetic classifications pedologists classify soil individuals into groups in order to communicate with each other about the properties of the soil individuals ideally the classification should be meaningful and not arbitrary some argue that it should be based on the genetics or evolutionary history of soil such that it predicts properties of newly discovered or poorly known soil individuals here we propose pedogenetic systematics which is an attempt to understand the pedogenetic interrelationships trying to interpret the way in which soil has diversified and changed over time pedogenetic systematics may be defined as the reconstruction of the pattern of events that have led to the distribution and diversity of soil this paper presents a mechanistic model for soil formation which considers the weathering of the bedrock and soil distribution by erosion using this model we simulated soil development in a landscape the simulated soil genetic properties at different times were grouped into numerical soil classes this allows us to follow the evolution of the soil classes with time starting with a single soil class thin soil soil individuals in the landscape develop into more complex and diversified soil classes this paper presents our first attempt to build a soil phylogenetic tree which allows us to begin formalising the concept of pedogenetic systematics

the implications of geology soils and vegetation on landscape morphology inferences from semi arid basins with complex vegetation patterns in central new mexico usa abstract this paper examines the relationship between land surface properties e g soil vegetation and lithology and landscape morphology quantified by the catchment descriptors the slope area s a relation curvature area c a relation and the cumulative area distribution cad in two semi arid basins in central new mexico the first site is composed of several basins located in today s desert elevations with mesic north facing and xeric south facing hillslopes underlain by different lithological formations the second site is a mountainous basin exhibiting vegetation gradients from shrublands in the lower elevations to grasslands and forests at higher elevations all three land surface properties were found to have significant influences on the s a and c a relations while the power law exponents of the cads for these properties did not show any significant deviations from the narrow range of universal scaling exponents reported in the literature among the three different surface properties we investigated vegetation had the most profound impact on the catchment descriptors in the s a diagrams of the aspect controlled ecosystems we found steeper slopes in north facing aspects than south facing aspects for a given drainage area in elevation controlled ecosystems forested landscapes exhibited the steepest slopes for the range of drainage areas examined followed by shrublands and grasslands in all soil textures and lithologies in the c a diagrams steeper slopes led to a higher degree of divergence on hillslopes and a higher degree of convergence in the valleys than shallower slopes the influence of functional types of vegetation detected on observed topography provided some initial understanding of the potential impacts of life on the organization of topography this finding also emphasizes the critical role of climate in catchment development we suggest that climatic fluctuations that are capable of replacing vegetation communities could lead to highly amplified hydrological and geomorphic responses

temporal changes of subsurface velocities during strong shaking as seen from seismic interferometry 1 we apply a deconvolution method to a strong motion data set recorded at the surface and in boreholes in northeast honshu japan we try to characterize the nonlinear effects of the subsurface soil during strong shaking and show the change of the subsurface velocity structure during the shaking the deconvolved waveforms reflect the subsurface velocity structure and their horizontal and vertical components correspond to s and p wave respectively traveling from the borehole to the ground surface the strong motion records with smaller values of peak acceleration do not include significant nonlinear effects so the deconvolved waveforms of the observed accelerations can be well simulated by the program shake91 for high acceleration motions during the shaking of two separate earthquakes large reductions of near surface velocities are seen in results for the 2008 iwate miyagi nairiku earthquake the large high frequency ground motions over 4g at one near source station caused a nonlinear response of the soil and the reduction of the average shear wave velocity reached 24 this corresponds to a stiffness change of over 75 the soil properties and the stiffness coefficient which changed during the shaking did not fully recover after the shaking leaving a static change

an assessment of the fluvial geomorphology of subcatchments in parana valles mars this paper uses a multifaceted remote sensing and morphometric approach to investigate if the surface of subcatchments in the parana valles area of mars 20 30 s 0 20 w is reflective of hydrology and sediment transport by water using digital elevation model dem data obtained from the mars orbiter laser altimeter mola three nested subcatchments were examined using a suite of terrestrial geomorphic and hydrologic statistics to determine if their shape and form lies within the known range of fluvial catchment properties on earth further an examination of statistical accuracy via an innovative pixel by pixel solution of two statistics established that despite mineralogical homogeneity confirmed by the compact reconnaissance imaging spectrometer for mars crism spectral survey erosion processes were likely to be variable across the study site the dem based methods outlined here can be employed at other sites to investigate geomorphic properties and attributes of the martian surface

seismic velocity reduction and accelerated recovery due to earthquakes on the longmenshan fault various studies report on temporal changes of seismic velocities in the crust and attempt to relate the observations to changes of stress and material properties around faults although there are growing numbers of observations on coseismic velocity reductions generally there is a lack of detailed observations of the healing phases here we report on a pronounced coseismic reduction of velocities around two locked sections asperities of the longmenshan fault with a large slip during the 2008 mw 7 9 wenchuan earthquake and subsequent healing of the velocities the healing phase accelerated significantly at the southern asperity right after the nearby 2013 mw 6 6 lushan earthquake the results were obtained by joint inversions of travel time data at four different periods across the wenchuan and lushan earthquakes the rapid acceleration of healing in response to the lushan earthquake provides unique evidence for the high sensitivity of seismic velocities to stress changes we suggest that stress redistribution plays an important role in rebuilding fault strength after a fault ruptures the recovery of its strength may be accelerated by earthquakes that redistribute stress according to an analysis of temporal variation in crustal seismic velocity on the longmenshan fault in china

environmental arsenopyrite stability and dissolution theory experiment and field observations arsenopyrite has traditionally been considered to be chemically unstable in the surficial environment however field evidence demonstrates that arsenopyrite does not readily decompose under water saturated near surface conditions arsenopyrite occurs in the heavy mineral suite of a variety of thin sediments in southern new zealand with no evidence for chemical corrosion these sediments have been water saturated but within metres of the surface for 10 60 28000 and 2 million years these observations of long term arsenopyrite stability are in accord with geochemical predictions based on recent experimentally determined thermodynamic data for arsenopyrite calculations using the new thermodynamic data suggest that arsenopyrite has similar eh ph stability range to pyrite except under acid conditions ph 4 where arsenopyrite should transform to realgar or orpiment calculated as concentrations in equilibrium with the pyrite arsenopyrite assemblage in the surficial environment are 0 01 0 1 ppm similar to groundwater in arsenopyrite bearing rocks in this study 0 005 0 3 ppm and these waters may be in chemical equilibrium arsenopyrite decomposes in oxidised waters to yield up to 1100 ppm dissolved as in the laboratory and up to 400 ppm dissolved as in mine processing waters these concentrations of dissolved as are several orders of magnitude lower than equilibrium solubility of arsenopyrite because of kinetic effects and development of protective oxide coatings on arsenopyrite grains mine tailings containing arsenopyrite should be chemically stable during longterm storage provided they are kept water saturated and moderately reduced d 2003 elsevier science b v all rights reserved

a seismological model for earthquakes induced by fluid extraction from a subsurface reservoir a seismological model is developed for earthquakes induced by subsurface reservoir volume changes the approach is based on the work of kostrov 1974 and mcgarr 1976 linking total strain to the summed seismic moment in an earthquake catalog we refer to the fraction of the total strain expressed as seismic moment as the strain partitioning function a probability distribution for total seismic moment as a function of time is derived from an evolving earthquake catalog the moment distribution is taken to be a pareto sum distribution with confidence bounds estimated using approximations given by zaliapin et al 2005 in this way available seismic moment is expressed in terms of reservoir volume change and hence compaction in the case of a depleting reservoir the pareto sum distribution for moment and the pareto distribution underpinning the gutenberg richter law are sampled using monte carlo methods to simulate synthetic earthquake catalogs for subsequent estimation of seismic ground motion hazard we demonstrate the method by applying it to the groningen gas field a compaction model for the field calibrated using various geodetic data allows reservoir strain due to gas extraction to be expressed as a function of both spatial position and time since the start of production fitting with a generalized logistic function gives an empirical expression for the dependence of on reservoir compaction probability density maps for earthquake event locations can then be calculated from the compaction maps predicted seismic moment is shown to be strongly dependent on planned gas production

induced seismicity of the groningen gas field history and recent developments abstract induced seismicity of the groningen gas field is caused by the production of gas because of the large areal extent of the reservoir the long history of depletion and the available data sets which exist as a result of consequences and public unrest caused by induced seismicity the field presents a valuable case for studying the relationships among geologic flow dynamic geomechanical and seismological models gas production from the groningen field started in 1963 induced seismicity of the field first was recorded in 1991 ml 2 4 during the subsequent 10 years induced seismicity stayed at a rate of about five events ml 1 5 per year starting in 2003 the number of events and magnitudes started to increase in 2012 the largest event ml 3 6 occurred which caused the most damage to date as a consequence studies carried out in 2013 have fundamentally changed the way to look at the relationship between induced seismicity and gas depletion there appears to be a close link between

the effect of spatial heterogeneities on geomorphic expression in a model of basin evolution spatial variability is a basic component of all natural systems the system being studied here is the topography of an evolving drainage basin spatially heterogeneous erosivity within the drainage basin influences the structure of the drainage network the roughness of small scale features and the overall appearance of the simulated topography the presence of heterogeneities does not simply blur and smear analytical relationships the heterogeneities themselves introduce new structure to the organization of the drainage basin three measures the slope area relationship the cumulative area relationship and the hypsometric distribution are all systematically affected by spatial heterogeneity we will demonstrate how and why these relationships are affected and also how different structures in the heterogeneities themselves are manifested in the resulting simulated topography

modelling landscape evolution geomorphology is currently in a period of resurgence as we seek to explain the diversity origins and dynamics of terrain on the earth and other planets in an era of increased environmental awareness yet there is a great deal we still do not know about the physics and chemistry of the processes that weaken rock and transport mass across a planet s surface discovering and refining the relevant geomorphic transport functions requires a combination of careful field measurements lab experiments and use of longer term natural experiments to test current theory and develop new understandings landscape evolution models have an important role to play in sharpening our thinking guiding us toward the right observables and mapping out the logical consequences of transport laws both alone and in combination with other salient processes improved quantitative characterization of terrain and process and an ever improving theory that describes the continual modification of topography by the many and varied processes that shape it together with improved observation and qualitative and quantitative modelling of geology vegetation and erosion processes will provide insights into the mechanisms that control catchment form and function this paper reviews landscape theory in the form of numerical models of drainage basin evolution and the current knowledge gaps and future computing challenges that exist copyright 2010 john wiley sons ltd

a lumped parameter model of groundwater influx to a mine adit in mountainous terrain 1 acidic and metal laden drainage from the portals of abandoned mines is a serious environmental problem in wet mountainous regions where steep hydraulic gradients ensure that fresh recharge waters are continuously flushed through the workings hydrogeological characterization of these sites is hampered by their geological complexity and their frequent inaccessibility this paper presents a material balance model for the groundwater capture zone associated with influx to a mountainside adit the model can be used to estimate bulk hydraulic properties of the rock surrounding an adit from hydrograph data commonly recorded at its portal this application is illustrated using data from the myra falls mining camp vancouver island british columbia by simultaneously fitting base flow recession slopes for hydrographs of discharge water table elevation and head in an underground borehole the model yields plausible and well constrained estimates of hydraulic conductivity porosity skin factor and hydraulic gradient

a rudimentary mechanistic model for soil formation and landscape development ii a two dimensional model incorporating chemical weathering the necessity for a quantitative analysis of pedogenesis has become more compelling in the last few decades in part one of this paper we proposed a rudimentary mechanistic model that considers soil formation spatially at the catena scale this paper extends the model for soil formation in a landscape conditioned by a digital elevation model and further illustrates the application of the model in quantifying pedogenesis the current model states that the change in soil thickness over time depends on the physical weathering rate of rock the loss due to chemical weathering and the transport of soil through erosion the rate of physical weathering or lowering of the bedrock surface is represented as an exponential decline with soil thickness the chemical weathering rate is modelled as a negative exponential function of both soil thickness and time assuming uni dimensional weathering the rate of chemical weathering can be expressed as a reduction in soil thickness the movement of materials in the landscape is characterized by diffusive transport the model is solved numerically using the finite difference approach and applied to a digital elevation model the results for simulation of soil formation in a landscape after 10 000 years shows that the soil accumulates thickens in the gullies and erodes thins in the ridges the soil from the upper slope is transported down slope by the erosion processes and fills the gullies soil thickness is highly correlated with the profile curvature the effect of climate rock type and land management is illustrated by different combinations of weathering rate and erosive diffusivity to illustrate the effect of irregularity and randomness on the stability of the solution and the soil development spatially correlated normally distributed random numbers were added to the initial soil elevation the small randomness appears to cause instability chaos in the system dimensionality analysis of the soil thickness as a function of time confirms the non linear chaotic behaviour of the model rather than merely random noise a difference plot of the soil thickness time series unveiled the presence of a strange attractor alternatively these results may be a result of numerical instability

rocks under strain strain induced time lapse time shifts are observed for depleting reservoirs pressure depletion as a result of oil and gas production creates changes in the stress and strain fields of the rock material both inside and outside the reservoir seismic waves propagating through these rocks have different traveltimes before and after depletion because the layer thicknesses change and the seismic velocity is altered by the changes in the stress and strain fields the cumulative change in two way traveltimes with depth is referred to as time lapse time shift

basin and river profile morphometry a new index with a high potential for relative dating of tectonic uplift abstract geomorphometry may be a powerful tool to describe the characteristics of the landscape s response to tectonic signals but the meaning of morphometric indices is often obscured by the interplay between the many variables controlling the geomorphological evolution moreover although the so called hypsometric integral refers to the basin scale most indices are generally derived from the river long profiles and thus focus mainly on the short term response of a drainage network to base level change providing limited information in regions of older and or moderate uplift here using the rhenish shield western europe an area of moderate quaternary uplift as a test case i attempt to build an index yielding a comprehensive view of the stage attained by the landscape s response and indirectly an evaluation of the timing of the triggering base level change this index called r 1 is a ratio of differences between the three integrals linked respectively to the classical basin s hypsometric curve to the main river s long profile and at the intermediate level to a drainage network s hypsometric curve while its ratio form minimizes the lithological effect on r 1 this index is strongly correlated with basin size regional correlation coefficients are in the range 0 88 0 93 reflecting the way an erosion wave propagates from the outlet of a basin toward its headwaters therefore it is not directly usable as a proxy for relative uplift age however one can show that the relation between r 1 and basin size is theoretically expected to change with time following uplift the slope s r of the linear relation r 1 f ln a first increases rapidly but briefly then it gradually diminishes over several million years this is fully confirmed by the analysis of r 1 and s r in the study area once its initial increase is completed assumedly in a few ten thousand years s r appears to be a reliable indicator of relative uplift or any other cause of base level lowering age

monitoring a building using deconvolution interferometry i earthquake data analysis abstract for health monitoring of a building we need to separate the response of the building to an earthquake from the imprint of soil structure coupling and from wave propagation below the base of the building seismic interferometry based on deconvolution where we deconvolve the wave fields recorded at different floors is a technique to extract this building response and thus estimate velocity of the wave that propagates inside the building deconvolution interferometry also allows us to estimate the damping factor of the building compared with other interferometry techniques such as cross correlation and cross coherence interferometry deconvolution interferometry is the most suitable technique to monitor a building using earthquake records for deconvolution interferometry we deconvolve the wave fields recorded at all levels with the waves recorded at a target receiver inside the building this receiver behaves as a virtual source and we retrieve the response of a cut off building a short building that is cut off at the virtual source because the cut off building is independent from the structure below the virtual source the technique might be useful for estimating local structure and local damage we apply deconvolution interferometry to 17 earthquakes recorded during two weeks at a building in fukushima japan and estimate time lapse changes in velocity and normal mode frequency as shown in a previous study the change in velocity correlates with the change in normal mode frequency we compute the velocities from both traveling waves and the fundamental mode using coda wave interferometry these velocities have a negative correlation with the maximum acceleration of the observed earthquake records

spatial and temporal evolution of injected co2 at the sleipner field north sea time lapse three dimensional 3d seismic surveys have imaged an accumulation of injected co 2 adjacent to the sleipner field in the north sea basin the changing pattern of reflectivity suggests that co 2 accumulates within a series of interbedded sandstones and mudstones beneath a thick caprock of mudstone nine reflective horizons within the reservoir have been mapped on six surveys acquired between 1999 and 2008 these horizons have roughly elliptical planforms with eccentricities ranging between two and four in the top half of the reservoir horizon areas grow linearly with time in the bottom half horizon areas initially grow linearly for about eight years and then progressively shrink the central portions of deeper reflective horizons dim with time amplitude analysis of horizons above within and below the reservoir show that this dimming is not solely caused by acoustic attenuation instead it is partly attributable to co 2 migration and or co 2 dissemination which reduce the impedance contrast between sandstone and mudstone layers growth characteristics and permeability constraints suggest that each horizon grows by lateral spreading of a gravity current this model is corroborated by the temporal pattern of horizon velocity pushdown beneath the reservoir horizon shrinkage may occur if the distal edge of a co 2 filled layer penetrates the overlying mudstone if the buoyant plume draws co 2 upward or if the effective permeability of deeper mudstone layers increases once interstitial brine has been expelled topographic control is evident at later times and produces elliptical planforms especially toward the top of the reservoir our results show that quantitative mapping and analysis of time lapse seismic surveys yield fluid dynamical insights which are testable shedding light on the general problem of co 2 sequestration

the use of digital elevation models in the identification and characterization of catchments over different grid scales this study examines the ability of well known hydrological and geomorphological descriptors and statistics to differentiate between catchments with spatially varying geology size and shape subject to the same climate in the northern territory australia the effect of digital elevation model grid resolution on these statistics is also examined results demonstrate that catchment descriptors such as the area slope relationship cumulative area distribution and hypsometric curve can differentiate between catchments with different geology and resultant morphology but catchment network statistics are insensitive to differences in geology examination of the effects of digital elevation model grid scale demonstrates that while considerable catchment information can be gained at digital elevation grids greater than 10 m by 10 m hillslope and hydrological detail can be lost geomorphic descriptors such as the area slope relationship cumulative area distribution width function and strahler statistics were shown to be sensitive to digital elevation model grid scale but the hypsometric curve was not consequently caution is needed when deciding on an appropriate grid resolution as well as the interpretation and analysis of catchment properties at grid scales greater than that for optimal hillslope and area aggregation definition copyright 2005 john wiley sons ltd

geospatial technologies and digital geomorphological mapping concepts issues and research geomorphological mapping plays an essential role in understanding earth surface processes geochronology natural resources natural hazards and landscape evolution it involves the partitioning of the terrain into conceptual spatial entities based upon criteria that include morphology form genetics process composition and structure chronology environmental system associations land cover soils ecology as well as spatial topological relationships of surface features landforms historically the power of human visualization was primarily relied upon for analysis introducing subjectivity and biases with respect to selection of criteria for terrain segmentation and placement of boundaries this paper reviews new spatio temporal data and geocomputational approaches that now permit earth scientists to go far beyond traditional mapping permitting quantitative characterization of landscape morphology and the integration of varied landscape thematic information numerous conceptual theoretical and information technology issues are at the heart of digital geomorphological mapping dgm and scientific progress has not kept pace with new and rapidly evolving geospatial technologies consequently new capabilities exist but numerous issues have not been adequately addressed therefore this paper discusses conceptual foundations and illustrates how geomorphometry and mapping approaches can be used to produce geomorphological information related to the land surface and landforms process rates process form relationships and geomorphic systems

abrupt changes in the rate of andean plateau uplift from reversible jump markov chain monte carlo inversion of river profiles abstract knowledge of the rate of surface uplift of the central andean plateau provides important boundary conditions for regional geodynamic models and paleoclimate reconstructions here we present a fully nonlinear inverse method to extract the rock uplift history of the central andean plateau from the cotahuasi river and its tributaries our approach is based on an analytical solution to the stream power model that relates elevation to rock uplift history under the assumptions of constant climatic conditions in space and time and spatially invariant rock uplift we use a bayesian framework that allows us to quantify the full state of knowledge of model parameters i e uncertainties trade offs the erosional efficiency defines the landscape response time and this must be determined using independent data therefore using thermochronometric data from the cotahuasi ocona canyon which record rapid fluvial incision at 13 10 ma we calibrate our results to infer a rock uplift history for the north central andean plateau we infer a pulse of rock uplift between 25 and 10 ma at rates as high as 0 25 km my however the rock uplift rate inferred during this pulse is not as high as is predicted if the central andean plateau grew as a result of loss of unstable lithospheric mantle therefore our results are more consistent with models requiring gradual uplift of the central andean plateau

a methodology for calculating the spatial distribution of the area slope equation and the hypsometric integral within a catchment 1 the area slope relationship and the hypsometric curve are well known catchment descriptors the main shortcoming of traditional area slope and hypsometry extraction methods is their limited ability to represent heterogeneity within the catchment here we present a new methodology for explicit calculation of the spatial distribution at a pixel scale within a catchment of the area slope parameters and the hypsometric integral this method allows us to create a quantitative representation of the area slope equation and the hypsometric integral which can potentially be used in a variety of geomorphologic applications the results show that the spatial distribution of both the area slope equation and the hypsometric integral are noisy at the pixel scale in order to reduce the noise three averaging techniques were examined subcatchment scale averaging was found to be the best at identifying the spatial distribution of the area slope equation and hypsometric integral at the subcatchment scale the spatial distribution of the area slope equation and the hypsometric integral approximated the spatial distribution of soil morphological and geological units of the goulburn river catchment in eastern australia the spatially distributed area slope results were tested using manually extracted subcatchment average area slope values and found to be well correlated the spatially distributed hypsometric integral was also well correlated with landform concavity and convergence the subcatchment scale averaging of the spatially distributed area slope equation and hypsometric integral is shown to be a promising tool for producing spatially distributed data the techniques are demonstrated on a catchment that has marked spatial variation in soils and geology the results show that the spatially explicit maps can potentially identify the spatial extent of these soil types and geological features and agrees well with existing soil maps

feasibility of borehole ambient noise interferometry for permanent reservoir monitoring the analysis of seismic ambient noise acquired during temporary or permanent microseismic monitoring campaigns e g improved enhanced oil recovery monitoring surveillance of induced seismicity is potentially well suited for time lapse studies based on seismic interferometry no additional data acquisition required ambient noise processing can be automatized to a high degree and seismic interferometry is very sensitive to small medium changes thus there is an opportunity for detection and monitoring of velocity variations in a reservoir at negligible additional cost and effort data and results are presented from an ambient noise interferometry study applied to two wells in a producing oil field in romania borehole microseismic monitoring on three component geophones was performed for four weeks concurrent with a water flooding phase for improved oil recovery from a reservoir in ca 1 km depth both low frequency 2 hz 50 hz p and s waves propagating through the vertical borehole arrays were reconstructed from ambient noise by the virtual source method the obtained interferograms clearly indicate an origin of the ambient seismic energy from above the arrays thus suggesting surface activities as sources it is shown that ambient noise from time periods as short as 30 seconds is sufficient to obtain robust interferograms sonic log data confirm that the vertical and horizontal components comprise first arrivals of p wave and s waves respectively the consistency and high quality of the interferograms throughout the entire observation period further indicate that the high frequency part up to 100 hz represents the scattered wave field the temporal variation of apparent velocities based on first arrival times partly correlates with the water injection rate and occurrence of microseismic events it is concluded that borehole ambient noise interferometry in production settings is a potentially useful method for permanent reservoir monitoring due to its high sensitivity and robustness

the use of a landscape simulator in the validation of the siberia landscape evolution model transient landforms siberia is a physically based model for the geomorphic evolution of landforms it is essential that the siberia model be tested or validated against controlled landform development previous studies have demonstrated that siberia is able to simulate declining equilibrium landforms and in this paper we examine siberia s ability to simulate landforms as they evolve to their declining equilibrium form these landscapes are termed transient landforms landscapes generated by siberia were compared to those produced by a physical model experimental model landforms at stages of evolution comparison of the experimental landscapes with the simulated landscapes using total mass hypsometric curve width function cumulative area distribution and area slope demonstrate that siberia can simulate the experimental model landscape during development i e transient landscapes copyright 2002 john wiley sons ltd

hypsometry of glaciated landscapes hypsometry frequency distribution of elevations is often used to characterize landscape morphology traditionally in the context of the degree of uvial dissection recently the hypsometry of glaciated regions has been used to infer how rates of glacial erosion compare with tectonic uplift rates however many factors other than tectonics can also exert a major in uence on the hypsometry of a glaciated landscape resulting in a wide variety of hypsometries using examples from the eastern sierra nevada california the western sangre de cristo range colorado and the ben ohau range new zealand we demonstrate that all else being equal the hypsometries of neighbouring basins can indicate the relative degree of glacial modi cation in each a selection of drainage basins from the rocky mountains shows that the position of the equilibrium line altitude ela within the drainage basin relief is a dominant variable in determining the hypsometry of a glaciated basin this is a non linear effect once the ela falls to some critical level the glaciers scour deeply below the ela causing a noticeably different hypsometry the hypsometry of an arbitrary region encompassing many drainage basins can disguise the variation present in the hypsometries and thus landforms of the individual basins unique local circumstances such as the presence of a mountain ice eld waiho basin southern alps substantial hanging valleys avalanche creek glacier national park a narrow outlet canyon sawmill creek sierra nevada and isolated geologic structures baker creek sierra nevada can have a major impact on the hypsometry of an individual basin copyright 2004 john wiley sons ltd

p and s velocity structure in the groningen gas reservoir from noise interferometry noise interferometry has proven to be a powerful tool to image seismic structure in this study we used data from 10 geophones located in a borehole at 3 km depth within the groningen gas reservoir in the netherlands the continuous data cross correlations show that noise predominantly comes in from above the observed daily and weekly variations further indicate that the noise has an anthropogenic origin the direct p wave emerges from the stacked vertical component cross correlations with frequencies up to 80 hz and the direct s wave is retrieved from the horizontal components with frequencies up to 50 hz the measured inter geophone travel times were used to retrieve the p and s velocity structure along the borehole and a good agreement was found with well log data in addition from the s wave polarizations we determined azimuthal anisotropy with a fast direction of n65 w 18 and an estimated magnitude of 4 2 the fast polarization direction corresponds to the present direction of maximum horizontal stress measured at nearby boreholes but is also similar to the estimated paleostress direction

scale dependence of hypsometric integrals an analysis of southeast african basins abstract previous studies have shown that the hypsometry of individual drainage basins is sensitive to both tectonic uplift rates and variations in erosional resistance of different lithological units however basin hypsometry has also been found to be related to the size the shape and relief of the sampled area as well as factors such as the type of dominant erosional process this study extends the evaluation of the controls on a basin s hypsometry by assessing factors that might influence the spatial distribution of hypsometric integrals at different scales the method is applied to catchments draining the southeast margin of southern africa kwazulu natal region because of the region s rather uniform runoff a rather well constrained denudational history and a relatively simple coastward sequence of bedrock geology several sets of basins were extracted from an srtm derived 90 m resolution dem one set of main basins those that have outlets at sea level and six sets of sub basins of different size based on strahler order the mean area of the sub basins sampled ranged from 9 km2 for strahler order 2 through to 3215 km2 for strahler order 6 in contrast to previous studies data from this study fail to show a correspondence between hypsometric integral and indices of basin dimension such as basin area and basin relief rather basin hypsometry in se africa varies spatially and with scale in particular a mountain range scale positive hypsometric integral anomaly situated between 10 and 100 km of the coast line was observed but only in basins of strahler order 5 and less this anomaly is compatible with moderate crustal displacement focussed midway between the coast and the drakensburg escarpment some intermediate scale positive hypsometric integral anomalies in basins of strahler order 4 and less was also observed in some cases these anomalies correspond to differences in erosional resistance among major lithological groups finally numerous local basin scale positive hypsometric integral anomalies in basins of strahler order 3 and less were also observed in many cases these latter anomalies are related to local differences in lithological resistance e g the presence of dolerite sills and dikes the analysis of the spatial variation of hypsometric integrals in basins of different size ranges is therefore a useful first step in assessing factors that control landscape development

channel head location and characteristics using digital elevation models the drainage network is the conduit through which much surface water and sediment are routed within a catchment in a catchment the position of where hillslopes begin and channels end has long been considered the position of transition between diffusive processes upslope and the more incisive fluvial processes downslope consequently understanding channel head location is an important issue in understanding catchment hydrology and geomorphology this study examines channel head position and characteristics in a catchment in arnhem land northern territory australia in this study the position of channel heads was mapped within the catchment and plotted on a reliable digital elevation model of the catchment it was found that the majority of channel heads have relatively small source areas and that graphical catchment descriptors such as the area slope relationship and cumulative area distribution can provide reliable measures of the field position of the heads of first order streams and the transition from hillslope to channel the area slope relationship and cumulative area distribution are also shown to be good tools for determining digital elevation model grid size which can capture hillslope detail and the transition from hillslope to channel copyright 2005 john wiley sons ltd

measuring the imprint of orographic rainfall gradients on the morphology of steady state numerical fluvial landscapes we explore the imprint of spatial rainfall patterns on steady state landscapes with uniform rock uplift rate a two dimensional 2d orographic precipitation module is incorporated into the child numerical landscape evolution model to provide a quantitative tool for exploring the co evolution of rainfall patterns and fluvial topography our results suggest that network organization and planform morphology are strongly impacted by rainfall patterns rainfall gradients that are perpendicular to a mountain range front produce narrower watersheds because channels show a tendency to flow along the rainfall gradient rather than across it the change in watershed shape is evidenced by smaller values of the exponent on distance in hack s law and a less peaked width function narrower watersheds also lead to an increase in the valley spacing ratio and constrain trunk channels to follow a more direct path to the mountain front rainfall gradients also influence the distribution of topography across a watershed channel profiles record rainfall patterns in both the channel concavity and the channel steepness index ksn across short tributaries along which rainfall rate changes little ksn decreases systematically with tributary averaged rainfall rate the hypsometric integral hi which increases with the amount of topography that is at relatively high elevations within a watershed is negatively correlated with the profile concavity of the trunk channel high rainfall rates at the ridge top lead to mainstem channels that have relatively low concavity and watersheds with relatively higher hi in comparison with landscapes that have uniform rainfall finally we contrast the impacts of rainfall patterns on landscape morphology with those resulting from a linear rock uplift gradient and uniform rainfall uplift patterns may have a similar impact on landscape morphology as rainfall gradients making it challenging to decipher the relative roles of climate and tectonics on landscape evolution without a quantitative assessment of morphologic parameters copyright 2015 john wiley sons ltd

review paper a semi empirical model of strain sensitivity for 4d seismic interpretation we reformulate the original model of hatchell and bourne and roste stovas and landro that couples fractional velocity change to subsurface strain via a fundamental constant r the new model combines elastic compressibility of a dual porosity system for a sand shale mixture with horizontal planes of inter granular weakness the majority of observed r factor magnitudes from post stack 4d seismic data in both the reservoir and overburden can thus be explained r is predicted to depend strongly on lithology and also initial strain state the model is also extended to predict the observed angle dependence of time lapse time shifts from pre stack data an expression for the gradient of time shift with incidence angle is obtained in terms of the background vp vs and also the ratio of tangential to normal compliances bt bn representing loss or creation of inter granular coupling if accurately estimated from data this compliance ratio can be used as an additional parameter to assess the post production state of the overburden it is concluded that whilst r remains the over arching parameter controlling the magnitude of time shifts measured from 4d seismic data bt bn is a subtler parameter that may also prove of future value

a physical explanation for an observed area slope elevation relationship for catchments with declining relief a general relationship between the contributing area slope and mean elevation of catchments with relief declining after a tectonic uplift event is presented this relationship is based on the continuity equation for runoff and erosion processes in the catchment the key hypothesis underlying this relationship is that as a catchment declines the nondimensionalized catchment approaches a constant form this hypothesis is verified for computer simulated catchments the area slope elevation relationship covers several cases catchments declining toward a peneplain catchments declining from a high slope dynamic equilibrium resulting from a high rate of tectonic uplift to a low slope one resulting from a lower rate of tectonic uplift and catchments declining from an elevated initial condition as for example in the decline of a mine spoil heap a previously published relationship between slope and area for catchments in dynamic equilibrium and based on runoff and erosion physics is shown to be a special case of this general relationship the new area slope elevation relationship is compared with data from simulated catchments and a field catchment it is thus shown that for declining catchments the area slope elevation relationship is a good predictor of catchment form for catchments with declining relief it is argued that the slope area elevation relationship is sufficient with the planiform drainage pattern to completely define the elevation properties of the catchment such as for instance the hypsometric curve

revisiting the hypsometric curve as an indicator of form and process in transport limited catchment hypsometry has historically been used as an indicator of geomorphic form of catchments and landforms yet there has been little work aimed at relating hypsometry to landform process and scale this paper uses the siberia catchment evolution model to explore linkages between catchment process and hypsometry siberia generates results that are qualitatively and quantitatively similar to observed hypsometric curves for physically realistic parameters however we show that not only does the hypsometry reflect landscape runoff and erosion process but it is strongly dependent on channel network and catchment geometry we show that the width to length ratio of the catchment has a significant influence on the shape of the hypsometric curve though little on the hypsometric integral for landforms dominated by fluvial sediment transport the classic strahler mature hypsometric curve is only generated for catchments with roughly equal width and length narrow catchments show a hypsometric curve more similar to strahler s monadnock form for landscapes dominated by diffusive transport the simulated hypsometric curve is concave down everywhere this being consistent with curves reported for some example catchments in france because the transition between diffusive dominance to fluvial is scale dependent with larger catchments exhibiting greater fluvial dominance then the hypsometric curve is a scale dependent descriptor of landforms experimental results for simulated landforms from a small scale rainfall erosion simulator are reported it is shown that siberia yields satisfactory fits to the data confirming its ability to predict the form of the hypsometric curve from a simple model of geomorphic processes 1998 john wiley sons ltd

a physical explanation of an observed link area slope relationship an observed log log linear relationship between channel slope and contributing area is explained by the erosional physics that lead to catchment form it is postulated that tectonic uplift is in balance with the fluvial erosion down wasting that dominates catchment erosion and it is shown that this relationship results in the observed log log linear relationship at dynamic equilibrium in addition it has been observed that there are deviations from this log log linear relationship near the catchment divide with observed slopes being lower than those predicted from the relationship this is explained by noting that for small areas fluvial erosion effects are dominated by soil creep and rain splash modeled by diffusive physics the area at which this deviation from log log linearity occurs is that point on the hillslope at which diffusive physics like soil creep and rain splash begin to dominate fluvial erosion these predictions are confirmed by numerical simulations using a catchment evolution model

structural monitoring of a highway bridge using passive noise recordings from street traffic structural damage on bridges presents a hazard to public safety and can lead to fatalities this article contributes to the development of an alternative monitoring system for civil structures based on passive measurements of seismic elastic waves cross correlations of traffic noise recorded at geophone receiver pairs were found to be sufficiently stable for comparison and sensitive to velocity changes in the medium as such velocity variations could be caused by damage their detection would be valuable in structural health monitoring systems a method originally introduced for seismological applications and named passive image interferometry was used to quantify small velocity fluctuations in the medium and thereby observe structural changes evaluation of more than 2 months of continuous geophone recordings at a reinforced concrete bridge yielded velocity variations v v in the range of 1 5 to 2 1 the observed fluctuations correlate with associated temperature time series with a striking resem

near surface weakening in japan after the 2011 tohoku oki earthquake 1 the magnitude mw 9 0 tohoku oki earthquake on 11 march 2011 was one of the largest in recent history ground motion caused by the seismicity around the time of the main shock was recorded by kik net the strong motion network that covers most of japan by deconvolving waveforms generated by earthquakes that are recorded at the surface and in a borehole at kik net station fksh18 we detect a reduction of shear wave velocity in the upper 100 m of about 10 and a subsequent healing that varies logarithmically with time using all available borehole and surface records of more than 300 earthquakes that occurred between 1 january 2011 and 26 may 2011 we observe a reduction in the shear wave velocity of about 5 in the upper few hundred meters after the tohoku oki earthquake throughout northeastern japan the area of the velocity reduction is about 1 200 km wide which is much wider than earlier studies reporting velocity reductions following other larger earthquakes the reduction of the shear wave velocity is an indication that the shear modulus and hence the shear strength is reduced over a large part of japan

trace element zoning in dolomite proton microprobe data and thermodynamic constraints on fluid compositions abstract lower cretaceous euhedral dolomite crystals from the gargano peninsula italy have been analyzed by scanning proton microprobe spm for the trace elements sr zn fe mn cu ni y and rb intricate decoupled zoning patterns for fe mn and zn are a ubiquitous feature of the outer 55 microns of the dolomite crystals differences between peak and baseline concentrations are on the order of several hundred parts per million in contrast sr concentrations are nearly constant at 110 ppm the concentrations of the other cations are all low cu 20 ppm y 10 ppm and ni and rb 5 ppm in order to investigate the origin of the gargano dolomite we have used the method of tardy and garrels to estimate equilibrium partition coefficients for divalent cations between aqueous fluids and the dolomite structure 18o measurements on gargano dolomites show that they formed at a maximum temperature of 75 c 7 c estimated equilibrium constants for substitution of the cation m into dolomite calculated baseline molar cation ratios for fluids in equilibrium with gargano dolomite and measured cation ratios for seawater and marine sediment pore fluids at 75 c are as follows m n k eq log10 calculated ratio log10m n measured ratio in seawater log10m n measured ratio marine pore fluids mn mg 1 27 4 62 7 17 2 75 fe mg 12 66 4 77 6 57 3 81 zn mg 6 85 5 27 6 72 4 84 sr ca 0 17 2 94 1 92 1 83 cation ratios of fluids in equilibrium with the baseline concentrations of mn fe and zn in the gargano dolomite samples are bracketed by the cation ratios measured in seawater and in marine sediment pore fluids the factor often discrepancy for sr in the predicted fluid compared with seawater is probably due to nonideal mixing of sr on the ca site the decoupled fluctuations of the mn and fe concentrations in these samples can be explained by eh fluctuations in the reactant fluid zn fluctuations may be a product of ph dependent oxide surface reactions to test this hypothesis of origin unzoned tertiary dolomites from enewetak atoll and from the bahama bank have also been analyzed the homogeneous sr concentration in the gargano dolomite is similar to the sr concentrations measured in the enewetak atoll 175 ppm and bahama bank 150 ppm dolomites samples which in both cases almost certainly grew in equilibrium with seawater gargano baseline mn 20 ppm and fe 80 ppm concentrations are also much the same as the bahama bank dolomite mn 15 ppm and fe 140 ppm concentrations the lack of sr zoning in the gargano samples and the similarity of their sr mn and fe content to dolomite that formed in equilibrium with seawater indicates that the dolomitizing fluid was most likely seawater or a seawater type brine low sr concentrations 12 ppm in pore filling calcite from the gargano suggests that in contrast to the dolomite the calcite precipitated from meteoric fluids

geochemistry of mine waters draining a low sulfide gold quartz vein deposit bralorne british columbia abstract the bralorne and pioneer mines now inactive produced over 4 million ounces of au from an orogenic lode au deposit located on the eastern edge of the coastal mountains of sw british columbia between 2007 and 2009 drainage from a recently developed exploration adit was investigated in order to better understand and anticipate potential environmental management issues associated with the development of this type of deposit in the future portal discharge rate and specific conductance were monitored continuously over a 14 month period during which 36 water samples were collected additional samples were collected from flooded workings within the adit concentrations of as and sb at the portal range as high as 1738 and 316 g l respectively while those in the mine pool reach 3304 and 349 g l respectively effluent chemistry is mildly alkaline ph 8 7 and is dominated by na ca mg hco3 and so4 geochemical inverse modeling of effluent composition indicates weathering of albite 2515 kg a ferroan dolomite 718 kg a pyrite 456 kg a arsenopyrite 23 kg a and stibnite 2 kg a modeled sulfide reaction coefficients normalized by their corresponding host rock concentrations suggest that oxidation of arsenopyrite is 25 times slower than that of pyrite whereas oxidation of stibnite is 1 5 times faster oxidative dissolution of arsenopyrite and stibnite releases 10 6 kg a of as and 1 1 kg a of sb of which 57 and 46 respectively are sorbed to ferrihydrite and gibbsite on the bed of the shallow channel through which the mine pool drains to the portal although mass balance calculations predict the formation of sufficient ferrihydrite to sorb 100 of the as dissolved in the mine pool this attenuation process was ineffective possibly because the precipitated sorbents settled to the bottom of the water column or because of competition for sorption sites from ca and hco3 the dissolved sb as molar ratio in portal effluent 0 082 is much greater than the sb as ratio of the mineralization 0 002 because of slower arsenopyrite oxidation and somewhat lesser sorption of sb

investigating links between climate and orography in the central andes coupling erosion and precipitation using a physical statistical model prior studies evaluated the interplay between climate and orography by investigating the sensitivity of relief to precipitation using the stream power erosion law spel for specified erosion rates here we address the inverse problem inferring realistic spatial distributions of erosion rates for present day topography and contemporaneous climate forcing in the central andes similarities in the altitudinal distribution and density of first order stream outlets and precipitation suggest a direct link between climate and fluvial erosion erosion rates are estimated with a bayesian physical statistical model based on the spel applied at spatial scales that capture joint hydrogeomorphic and hydrometeorological patterns within five river basins and one intermontane basin in peru and bolivia topographic slope and area data were generated from a high resolution 90 m digital elevation map and mean annual precipitation was derived from 14 years of tropical rainfall measuring mission 3b42v 7 product and adjusted with rain gauge data estimated decadal scale erosion rates vary between 0 68 and 11 59 mm yr with basin averages of 2 1 8 5 mm yr even accounting for uncertainty in precipitation and simplifying assumptions these values are 1 2 orders of magnitude larger than most millennial and million year timescale estimates in the central andes using various geological dating techniques e g thermochronology and cosmogenic nuclides but they are consistent with other decadal scale estimates using landslide mapping and sediment flux observations the results also reveal a pattern of spatially dependent erosion consistent with basin hypsometry the modeling framework provides a means of remotely estimating erosion rates and associated uncertainties under current climate conditions over large regions 2014 american geophysical union all rights reserved