impact of mesh and dem resolutions in sem simulation of 3d seismic response this study shows that the resolution of a digital elevation model dem and model mesh strongly influences 3d simulations of seismic response topographic heterogeneity scatters seismic waves and causes variation in seismic response am plification and deamplification of seismic amplitudes at the earth s surface dem resolution influences the accuracy and detail with which the earth s surface can be represented and hence affects seismic simulation studies apart from the spatial resolution of a dem the mesh resolution adopted in the creation of a 3d spectral element meshing also changes the detailedness of surface topography working with high resolution data is in most cases not possible on a regional scale because of its costliness in terms of time money and computation in this study we evaluate how low the resolution of dem and mesh can become before the results are significantly affected we simulated models with different combinations of dem and mesh resolutions the peak ground displacement pgd obtained from these simulations was compared with the pgd of the model with the finest mesh and dem resolution our results show that any mesh or dem resolution of 540 m or coarser will give unrealistic results these results are valid for similar terrains as studied here and might not be directly applicable to regions with significantly different topography

predicting regolith thickness in the complex weathering setting of the central mt lofty ranges south australia abstract we describe a model to predict regolith thickness in a 128 000 ha study area in the central mt lofty ranges in south australia the term regolith encompasses soil a and b horizons and highly weathered bedrock c horizon the thickness of the regolith has a major control on water holding capacity for plant growth and movement of water through the landscape and as such is important in hydropedological modelling and in evaluating land suitability e g for forestry and agriculture thickness estimates also have direct application in mineral exploration and seismic risk assessment geology and landscape evolution within the study area is complex reflecting the variable nature of bedrock materials and the partial preservation of deeply weathered profiles as a consequence of weathering processes dating to the cenozoic or possibly older these characteristics together with strong climatic gradients make the study area an ideal location to understand environmental and landscape evolution controls on weathering depth the area also features weathered landscape analogues to many parts of southern australia we use a digital soil mapping rules based approach to develop a model to predict regolith thickness this model uses statistically based relationships established between 714 regolith thickness measurements and 29 geographic environmental covariates including geology geochemistry terrain and climate themes and with a ground resolution of 10 m accuracy testing based on a 75 25 training test data split on the resulting map established a correlation r 2 of 0 64 this result is encouraging and is a significant advance over regolith depth mapping by traditionally based regolith landscape mapping methods finally it leads the way towards a nationally consistent regolith thickness map for landscape scale environmental simulation modelling and decision support

spatial and temporal monitoring of soil moisture using surface electrical resistivity tomography in mediterranean soils abstracts ert techniques are especially promising in semi arid areas with shallow and rocky soils where other methods fail to produce soil moisture maps and to obtain soil profile information electrical resistivity tomography ert was performed in the peyne catchment in southern france at four sites located on four different geological substrates the main objective was to test the usefulness of such geoelectrical method for the assessment of spatial and temporal variability of soil water content and to demarcate subsurface horizontal zones topsoil active zone and bedrock we used time lapse ert to separate lithological variability from soil moisture content and to evaluate its potential to demarcate subsurface soil horizons three measurement campaigns were carried out and field data were collected using the sting r1 ip advanced resistivity meter with one channel receiver we used an array of 28 electrodes with 1 m spacing which provided reliable resistivity information to a depth of approximately 5 5 m ert were followed by soil sampling carried out with a hand auger directly below the respective geoelectrical profiles empirical linear regression was used to determine the specific relationships between volumetric soil moisture of the field samples and electrical resistivity data obtained in situ our conclusions are that ert is a useful technique for providing information on the spatial temporal variability of water content in semi arid areas and for reaching depths otherwise inaccessible in this study we proposed a method to delineate three important different soil zones topsoil active zone bedrock based on resistivity data these three layers are essential information in understanding and modelling the interaction between subsurface and vegetation water uptake particularly in semi arid regions

spatial modelling and uncertainty assessment of pyroclastic cover thickness in the sorrento peninsula assessing spatial variability of soil thickness is a critical issue for understanding and predicting slope processes the present work was aimed at estimating the spatial scales at which the variation of pyroclastic cover thickness occurs in a sample area in the sorrento peninsula italy stochastic simulation was used to understand the spatial variability of pyroclastic cover thickness on mount pendolo and to assess its spatial uncertainty in the study area covering about 0 7 km2 thickness measurements were collected using electrical resistivity tomography profiles continuous core drillings and steel rod penetrometric tests variographic analysis revealed the occurrence of an anisotropic behaviour along the n50 and n140 directions in the latter anisotropic direction a nested variogram was fitted including 1 a long range component which could be related to large scale factors like the curvature of the slope and contributing area and 2 a shorter scale variation which is probably associated with the occurrence of denudation processes or to the articulate cover bedrock interface to assess the spatial variability and uncertainty of pyroclastic cover thickness a stochastic simulation algorithm was used and 500 equally probable images of cover thickness were yielded the results showed that a better thickness distribution map can be drawn by simulating the data collected on the slope and at the footslope separately the approach also allowed delineating the areas characterized by greater uncertainty suggesting supplementary measurements to further improve the cover thickness distribution model thus reducing the uncertainty

surficial slip and rupture geometry on the beichuan fault near hongkou during the mw 7 9 wenchuan earthquake chinasurficial slip and rupture geometry on beichuan fault near hongkou during the wenchuan earthquake

mapping the distribution of weathered pleistocene wadi deposits in southern jordan using aster spot 5 data and laboratory spectroscopic analysis abstract in the arid regions of the levant ancient wadi fills act as a terrestrial sedimentary archive with a high potential for preserving archaeological findings this current study combines remote sensing with laboratory vis spectroscopy to investigate the spatial distribution of alluvial wadi fills in a small catchment in southern jordan due to its homogeneous sandstone geology the composition of the alluvial sediments is highly influenced by the local bedrock whilst fluvial relocation and surface weathering processes initiated a secondary alteration of dominant iron oxides fe 3 the differences in mineralogical composition of the sediments enable the detection and mapping of wadi deposits by remote sensing using different spectral combinations of aster and spot 5 satellite images additionally laboratory measurements of reflectance spectra were applied on selected surface samples and soil sections from the study area in order to verify the information derived from remote sensing and to quantify the degree of surface weathering and pedogenic processes the results show that an initial transformation from hematite to goethite is the dominant process related to the recent arid conditions in the study area furthermore it is possible to predict potential new archaeological finding areas using remote sensing techniques

geophysical and remote sensing based approach to model regolith thickness in a data sparse environment abstract mapping regolith thickness to bedrock is important for environmental modeling in general and for seismic hazard assessment in particular however regolith thickness is often ignored in such studies because of its presumed difficulty of mapping in many terrains to overcome this limitation we developed a generic remote sensing and geophysics based approach to model regolith thickness for areas with limited possibility of direct field observations the approach was tested in a seismically active and depositional landscape in northern pakistan regolith thickness was sampled at exposed bedrock outcrops along the river bed and scarps at unexposed sites the regolith bedrock interface was identified through electrical resistivity survey thus providing an indirect measurement of regolith thickness a geomorphic classification of landforms and topographic attributes were derived from a remote sensing based aster digital elevation model and spot 5 satellite imagery landform was the most important predictor adjusted r2 72 1 showing the importance of geomorphic interpretation a multivariate linear model based on landform elevation and distance to stream was able to predict the regolith thickness adjusted r2 91 7 including field observed abrupt changes at landform boundaries

fractured but not fractal fragmentation of the gulf of suez basement recent geophysical studies revealed that the palaeozoic basement of the gulf of suez consists of an enormous number of fault blocks whose network qualitatively resembles the contractioncrack polygons which can be found in nature in a wide variety of materials and on all scales mud cracks hardening concrete age cracking in paintings etc the fault network of the gulf of suez basement forms a rather uniformly spaced polygonal pattern most of the blocks are four sided the lengths of block sides parallel with the gulf of suez axis are exponentially distributed the power law size distribution associated with the fractal scale free fragmentation can be possibly ruled out

regolith modeling and its relation to earthquake induced building damage a remote sensing approach regolith thickness is known as a major factor in influencing the intensity of earthquake induced ground shaking and consequently building damages it is however often simplified or ignored due to its variable and complex nature to evaluate the role of regolith thickness on earthquake induced building damage a remote sensing based methodology is developed to model the spatial variation of regolith thickness based on dem derived topographic attributes and geology regolith thickness samples were evenly collected in geological formations at representative sites of topographic attributes topographic attributes elevation slope twi distance from stream computed from the aster derived dem and a geology map were used to explore their role in spatial variation of regolith thickness stepwise regression was used to model the spatial variation of regolith thickness in erosional landscape of the study area topographic attributes and geology explain 60 of regolith thickness variation in the study area to test if the modeled regolith can be used for prediction of seismic induced building damages it is compared with the 2005 kashmir earthquake induced building damages derived from high resolution remote sensing images and field data the comparison shows that the structural damages increase with increasing regolith thickness the predicted regolith thickness can be used for demarcating site prone to amplified seismic response

measurement and characterisation of spatial distributions of fractures abstract a variety of line sample 1 d and map 2 d datasets of faults and joints has been used to investigate the spatial distributions of fractures and to test techniques of fractal analysis the natural fracture datasets have been supplemented by synthetic datasets with known characteristics the fault datasets investigated range in scale from regional to outcrop and the joint datasets are derived from outcrop 1 d datasets were analysed by the spacing population interval counting and fracture number interval counting techniques 2 d datasets were analysed by box counting and fracture number box counting techniques results indicate that fracture spacing can be characterised in line samples using either the 1 d interval counting technique or more simply by measuring the spacing population as the cumulative frequency distribution of spaces between adjacent fractures tectonic faults frequently show a power law spacing population indicating fractal dimensions of between 0 4 and 1 0 but except for outcrop data truncation effects degrade the analysis unrefined joint datasets commonly show negative exponential or lognormal spacing cumulative frequency distributions however single orientation joint sets are characterised by a regular spacing and are therefore non fractal for both fault and joint map data box counting techniques do not yield the power law relationship between box size and the number of boxes that is expected of fractal geometries it is concluded that 2 d box counting techniques are too insensitive to characterise the many different parameters of a fracture array the fracture density technique appears not to discriminate between very different fracture patterns and therefore does not provide useful results a fracture pattern incorporates several attributes e g size distribution orientation linkage density roughness each of which may scale independently and each of which may be fractal with its own fractal dimension full characterisation of fracture patterns will therefore require independent analysis of each of these attributes

comparisons of dry ert diachronic ert and the spectral analysis of surface waves for estimating bedrock depth in various mediterranean landscapes abstract bedrock depth provides important information for many applications such as groundwater modelling the estimation of soil water availability and crop production potential direct estimates of bedrock depth from destructive soil observations are discontinuous and too expensive to be used in large areas geophysical methods are often cited as possible alternatives however their ability to provide reliable estimations of bedrock depth relies greatly on local site characteristics therefore this study examines the ability of electrical resistivity tomographie ert in dry conditions diachronic ert and the spectral analysis of surface waves sasw method to determine bedrock depth bd in different geopedological contexts that are representatives of the mediterranean landscape southern france sasw was performed using the data that were measured in the field with classical seismic equipment impulse source and geophones along a transect in each study site in the same place transects of ert wenner schlumberger array 1 m electrode spaced were measured under wet and dry conditions to calibrate the geophysical measurements 131 boreholes from two to 5 m deep were interpreted to determine the bedrock depth dry ert diachronic ert and sasw were found to have highly variable performances for the estimation of bedrock depth in all geopedological contexts sasw correctly estimated the bedrock depth rmse 0 3 0 7 m in all situations except in the case of shallow soils conversely dry ert only estimated bedrock depth rmse 0 2 m in the case of a high contrast of the resistivity between the soil and bedrock by analysing the pattern of the water uptake by grapevine diachronic ert determined the bedrock depth in the case of very low contrasts in resistivity rmse 0 5 according to a prior pedological knowledge such soil maps the combination with the use of a sensor based on different physical parameters may enhance the bedrock detection

evaluation of remote sensing based seismic site characterization using earthquake damage data terra nova 24 123 129 2012 abstract preparing seismic site characterization maps requires extensive geological and geotechnical data collection and interpretation this study evaluates a remote sensing based method to generate seismic site characterization map at 30 m spatial resolution geographical object based image analysis was applied to topographic attributes computed from an advance spaceborne thermal emission and reflection radiometer digital elevation model to demarcate terrane units of mountains piedmonts and basins classified terrane units were verified through a field based landform map resulting in an accuracy of 70 to evaluate the importance of classified terrane units for seismic site characterization and their role in earthquake induced building damage the classified terrane units were compared with 2005 kashmir earthquake damage data derived from field visits and spot 5 imagery this shows that 81 of the less moderate and severe damage intensity zones correspond with mountains piedmonts and basins respectively classified terrane units were assigned vs30 to generate a seismic site characterization map

fractal and multifractal measures of natural and synthetic fracture networks we have analyzed the fractal and multifractal nature of a series of 17 natural fracture trace maps representing a wide variety of scales geological settings and lithologies as well as a number of typical synthetic fracture networks in which fracture locations orientations and lengths are drawn from various probability distribution functions recent studies have shown that multifractal methods can be used to investigate fracture networks at greater depth since the fractal dimension represents only part of the scaling spectrum characterizing each network we find that the real and synthetic fracture maps display fractal and multifractal properties moreover the properties of the synthetic networks are very similar to those of the real networks with nontrivial fractal dimensions and multifractal spectra we suggest that different fracturing mechanisms can lead to two or more distinct subranges over which a fractal dimension can be defined while the heterogeneity of the rock and the nature of the fracturing mechanisms lead to multifractal properties we also find that the fractal dimension of a synthetic fracture network is relatively insensitive to parameters such as fracture length and orientation but can be controlled by appropriate choice of the relative fracture density

fractal analysis of fracturing in two african regions from satellite imagery to ground scale abstract in two test areas of africa the fractal character of fracture fields was analyzed at very different scales on fracture maps from satellite images and from interpretation of drainage networks on topographical maps aerial photographs and ground photographs three different methods were used and the results criticized it was generally found that the area studied in western africa displays more fractal features than the area examined in central africa this might be related to the number and mechanism of fracturing phases in each region

detecting alpine landforms from remotely sensed imagery a pilot study in the bavarian alps abstract this study investigates the suitability of remote sensing for detecting rock and sediment storage areas in the reintal subcatchment 17 km2 east of zugspitze germany first characteristic features of alpine landforms such as curvature process coupling or type of deposited sediment were compiled based on this a landform classification was performed topographical information from a digital elevation model dem and spectral data from an aster advanced spaceborne thermal emission and reflection radiometer satellite scene were classified using a multiscale object oriented approach comprising four differently scaled levels the complex decision tree hierarchy is based for the most part on fuzzy membership functions and to a lesser extent on the hard nearest neighbour classifier the results show that both an identification of the present day pattern of storage types and the classification of geomorphologic units also with regard to their activity status and complexity is largely possible moreover the methodology developed in this study permits a first assessment of the upper regions of the study area which could not be included in any previous survey because of their inaccessibility coherent landform classification using remote sensing methods as developed in this study constitutes a promising scientific approach especially with regard to the enhanced spatial and spectral resolution of modern satellite systems

a case study of the reliability of multielectrode earth resistivity testing for geotechnical investigations in karst terrains abstract the thinly mantled karst areas of northeastern pennsylvania have been associated with a number of structural failures caused by sinkholes geotechnical investigations in these areas have primarily relied upon intrusive probe tests either through borings or air track drillings the silty clay soils overlying the carbonate bedrock have limited the use of nonintrusive ground penetrating radar and electromagnetic methods however multielectrode earth resistivity testing may be a suitable method for locating subsurface features associated with sinkhole formation in these areas the case study presented in this paper concerns a site in northampton county where sinkholes have been occurring at an accelerated rate due to the influence of construction the bedrock at the site is located between 1 m and approximately 10 m below the surface the soil is primarily a silty clay seventy resistivity lines using a variety of electrode and line spacings were conducted at the site using the data obtained from the earth resistivity tests 17 borings were located to assess the accuracy of the resistivity results comparisons between boring and resistivity results demonstrate that the resistivity tests provide good information concerning the depth to the irregular surface of the bedrock however use of the test to locate subsurface anomalies associated with sinkhole formation and to determine their size will require additional research the paper presents the results of the study and provides recommendations for geotechnical investigation in silty clay soils overlying shallow carbonate bedrock

a regolith depth map of the australian continent abstract the regolith is defined as weathered in situ and transported material overlying unweathered bedrock as fresh bedrock exposures form a small proportion of the landscape regolith is common in australia and varies in depth from less than a metre in upland settings to many hundreds of metres e g the cenozoic basins because of crucial fluxes in gases water nutrients and dissolved salts and variation in permeability and connectivity knowledge of the nature and depth of regolith is important to many land based industries including agriculture and forestry the minerals industry sees regolith as a barrier to discovery of mineralised rock at depth or as a host of minerals in economic concentrations there are clearly a range of important characteristics of regolith depth and therefore the quantity of regolith is fundamental for resource inventory and biophysical modelling applications a method is described that maps the depth of regolith with estimates of mapping uncertainty to the moderately weathered saprock boundary for the whole of australia our approach draws on an extensive legacy of publically available drillhole data of variable attribute consistency and applies an environmental correlation style of digital mapping prediction that utilises relevant spatial covariates e g terrain analysis climate and gamma radiometric datasets from the original database of 350 000 records we filtered and harmonised a useable dataset of 128 000 records key predictive datasets used in the depth model included weathering intensity lithology age distance to out crop elevation and relief shallowest cover corresponded to high relief erosional landscapes and deepest corresponded to cenozoic basin sediments the final map with a ground resolution of approximately 90 m 3 arcsec was generated using 100 bootstrap model iterations the reliability of the model was assessed using measures of r square 0 38 lin s concordance 0 51 mean error 5 73 m and root mean squared error 24 56 m calculated on a withheld test dataset the regolith depth map is consistent with known areas of deep in situ weathering and accumulation of recent sediment associated with the distribution of cenozoic basins and provides a testable estimate in areas with little drilling or survey history the predictive modelling approach provides a framework to further build and improve regolith depth prediction across varying spatial scales where sufficient quality drillhole data and environmental predictors exist and set priorities for new data acquisition

fractal analysis of fractures in rocks the cantor s dust method abstract the cantor s dust method of fractal analysis has been used to describe the regularity of fracture patterns in geological materials seen on a two dimensional surface this linear method of analysis is well adapted to a determination of two dimensional phenomena the determination of the fractal dimension d indicates that it varies regularly as a function of the orientation of the analysis direction this is taken to indicate that there is a relation unexplained as yet between the regularity of the fracture pattern and the forces which produced it the use of the cantor s dust method on naturally fractured materials ranging in dimension from 3 mm to 45 m in maximum dimension indicates the fractal nature of the fractures found in natural materials the analysis method can also be used to identify local variations in the stress field which caused failure such as the fractures in a feldspar compared to those in the host granite etc the method appears to be a sensitive descriptive measure of the failure patterns in rocks

architecture of the deep critical zone in the rio icacos watershed luquillo critical zone observatory puerto rico inferred from drilling and ground penetrating radar gpr

fractal clustering of metamorphic veins metamorphic veins record the fracture controlled flow of fluids throughout the oceanic and continental crust i show that the spatial distributions of veins from three diverse metamorphic settings are fractal and self similar vein densities were measured by counting the number of macroscopic veins intersected along linear transects the localities included wol lastonite quartz veins in marbles for which the fractal dimension d is 0 46 actinolite chlorite veins in hydrothermally altered oceanic diabases d 0 81 and epidote quartz veins in contact metamorphosed basalts d 0 25 0 63 the fractal clustering of veins provides a geometric framework for understanding spatial and temporal patterns of fluid flow and mineral reaction during metamorphism