assessment of heavy metals concentrations with emphasis on arsenic in the tabriz plain aquifers iran the tabriz area is one of the most industrialized areas in northwest of iran the heavy industrialization and the increasing urbanization are responsible for the rapidly increasing stress on the groundwater of the area the objective of this study was to evaluate heavy metals such as fe mn al zn as and cr in groundwater and their spatial distribution in tabriz plain aquifer the concentrations of fe cr mn as and al in some of the groundwater samples exceed the maximum admissible concentration mac correlation matrix cm and principal components analysis pca methods were employed to identify source apportionment of contamination parameters in groundwater there are two types of aquifers with different quality of water in the plain an unconfined aquifer with saline water and a confined aquifer with fresh water quality arsenic concentrations in the unconfined aquifer and in the recharge areas of the plain boundary are low with an average of 25 8 g l while in the confined aquifer and deep wells the concentrations are high with an average of 122 5 g l the arsenic occurring in groundwater resources of the area originates from geological formations such as alluvial tuffs of sahand mountain and its concentration is highly dependent on hydrogeological and environmental reducing conditions residence time of water and depth of the sampling wells

a study of the hydrogeological environment of the lishan landslide area using resistivity image profiling and borehole data abstract resistivity image profiling rip surveys was used to develop a lithological and hydrogeological model of the subsurface in the southeastern part of lishan landslide area of central taiwan the bedrock consists of slate in the study area based on rip and rock samples collected from boreholes results three electrical strata are recognized colluvium the shear zone composed of shear gouges and shattered slate and the undisturbed slate formation the steep shear zone with resistivity ranging between 100 260 m plays a crucial role in the local hydrogeological environment because it forms a natural barrier which blocks and retains groundwater flowing down the slope groundwater will brim over the barrier when the water level is high thus the inclined groundwater table remains stable from long term monitoring it strongly indicates that the groundwater recharge is greater than that of discharge therefore the shear zone can provide information about the optimum locations for draining the excess groundwater in situ for slope stability consideration the curved basal surface of the colluvium and the weathered slate can also be discerned from the resistivity variations and boreholes data a series of circular patterns may associate with the main slope failure which migrated upwards from the lower slope

geophysical investigation of a large landslide in glaciolacustrine clays in the trieves area french alps abstract slope movements in clay deposits are spread all over the world and result from complex deformation processes including internal strains in the landslide body and slipping along rupture surfaces such mass movements are likely to generate changes in the geophysical parameters characterizing the ground which can be used to map the landslide body in the last decade geophysical techniques have been increasingly used for landslide investigation purposes however the success of any geophysical technique is overall controlled by the existence of a geophysical contrast differentiating the body to be mapped for landslides affecting thick clay materials from soft clay to shale or marl electrical and seismic techniques have been mainly applied in the past in this study we attempt to physically characterize the deformation within a large slide avignonet affecting laminated clays which were deposited in a glacially dammed lake during the wurm period clay deposits which cover an area of 300 km2 south of grenoble french alps and have a maximum thickness of 200 m overlay compact alluvial layers and marly limestone of mesozoic age piezometric data at avignonet show that the water table is very shallow implying that the slide developed in saturated clay several seismic and electrical profiles were performed in order to tentatively correlate the variations of p wave vp velocity s wave velocity vs and electrical resistivity with geotechnical data and morphological observations in such saturated and fine material it turned out that only the s wave velocity exhibits significant variations with the displacement rates and the morphological features vs values at shallow depth were found to be inversely correlated with displacement rates measured by gps with a division by at least a factor of 2 between the zones unaffected and strongly deformed by the landslide these results suggest that vs mapping could provide valuable information on the deformation state of the clay material and that the evolution of vs with time could be used as an indicator for characterizing the landslide activity in the subsurface including the evolution into a flow

determination of mechanisms and hydrogeological environments of gangxianlane landslides using geoelectrical and geological data in central taiwan electrical resistivity tomography ert single point resistance logging with time lapse and geological and groundwater level data are utilized to determine the mechanism of and a hydrogeological model of the gangxianlane landslide in the west central part of taiwan the rock surface and geometry of the colluviums were found by integrating ert and borehole data the iso resistivity line in the bedrock broadly followed the bedding plane indicating that the contribution of lithology to resistivity exceeds that of groundwater the results of single point resistance logging with time lapse and borehole data reveal that the bedrock has low permeability which is associated with poorly developed joints and fractures the fine grain content part including the clayey layer almost parallel to the bedding plane of the bedrock and between the colluvium and the bedrock in the upper part of the landslide served as the slip surface and is believed to have been recently produced it can block and retain water in the colluviums accordingly this slip surface has the potential to re slip in the future another slope failure involved rock collapse by a well developed open release joint close to the huoshaoping terrace it is also related to groundwater flow over a large gradient from the huoshaoping terrace it is a key to determining whether this landslide will expand in the future

the geochemistry and petrology of the late precambrian georgeville group a volcanic arc rift succession in the avalon terrane of nova scotia

application of electrical resistivity tomography technique for investigation of landslides a case from turkey electrical resistivity imaging is a widely used tool in near surface geophysical surveys for investigation of various geological environmental and engineering problems including landslide in this study an electrical resistivity tomography ert survey was conducted in a landslide area located in the soke district of aydin turkey in 2003 the neogene aged units on the slope next to a newly built school building became unstable due to an excavation work and moved after a heavy rainfall the resulting landslide partly covered the school the authors carried out a 2 d resistivity survey along three profiles over the landslide mass using a wenner configuration it yielded useful information about the geometry and characteristics of the landslide in addition a 2 d synthetic resistivity modelling study was carried out to understand the response of the resistivity method to a landslide problem before the field surveys eight boreholes were also drilled in the landslide area both the drilling and resistivity results indicated the presence of a fault in the site also the resistivity data from the line measured along the axis of the landslide revealed the surface of rupture

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

resistivity and induced polarization surveys for slope instability studies in the swiss alps a geoelectrical investigation has been carried out in the swiss alps near the dent de nendaz within the southern part of the rhone valley in the swiss alps to delineate groundwater circulation within an unstable slope this unstable zone is characterized by a landslide area with clear scarps and hummocky ground at the bottom of the slope large scale apparent resistivity mapping provided information on the main pathways for water transport within the slope subsequently 2d resistivity and induced polarization imaging supplied details on the region of instability located at the bottom of the slope polarizable units identified in the region of instability could be linked to a clay rich unit or to local enrichment of graphite within the bedrock our results illustrate how low permeability clay graphite units and permeable water bearing units could be distinguished using a combined interpretation of resistivity and ip data in slope instability studies

groundwater flow after heavy rain in landslide slope area from 2 d inversion of resistivity monitoring data in the interest of monitoring the flow of groundwater from heavy rains we conducted surface resistivity tomography through the vadose zone over several days the measured data were modeled by 2 d inversion a laboratory experiment was carried out to estimate the difference in geological characteristics we measured the effects of groundwater fluctuation using two tank models one using sand and one using bricks which represent unconsolidated sediments and jointed rocks respectively in the sand model we succeeded in monitoring water level fluctuation as the change in resistivity over time in the brick model the water level did not appear as a distinct boundary field experiments were carried out in an area in which the near surface conditions consisted of heavily weathered rocks with an extensive shear zone several tens of meters thick measurements were performed over 42 days during which we observed changes in resistivity associated with heavy rainfall it became clear that resistivity decreases of up to 8 were present in highly porous zones in heavily weathered layers this result suggests a connection between a decrease in resistivity and the infiltration of rainwater in particular a pronounced zone of minimum resistivity may indicate infiltration of rainwater into the vadose zone the relationship between resistivity changes and rainfall was inferred to depend on the permeability of geological structure

the upper hadrynian jeffers group cobequid highlands avalon zone of nova scotia a back arc volcanic complex the upper hadrynian jeffers group of the cobequid highlands avalon zone of northern nova scotia consists of volcanic rocks of the gilbert hills formation interfingering deeper water argillite of the humming brook formation and overlying turbidite lithic arkose and siltstone of the cranberry lake formation the jeffers group has a spatially inhomogeneous flat lying cleavage associated with thrust faults of late hadrynian age that were in part reactivated during carboniferous strike slip motion on the cobequid fault the basal rocks of the gilbert hills formation consist of felsic pyroclastics and minor mafic and felsic flows of the lakelands facies locally passing up into sandstone and marble overlain by the humming brook formation thrust over this sequence is the harrington river facies of the gilbert hills formation comprising flows ranging in composition from subalkalic basalt to rhyodacite and pyroclastic rocks two groups of igneous rocks are distinguished geochemically high ti basalts of the lakelands facies and associated hypabyssal intrusions have tholeiitic character enrichment in ba rb and k flat light ree spectra little or no depletion in nb and ta and high feo t and ti they are associated with voluminous felsic rocks the harrington river facies has a calc alkaline differentiation series from basalt to rhyodacite but with more enrichment in feo t p nb and zr than is found in typical calc alkaline rocks these two groups are also represented in hypabyssal rocks the jeffers group rocks are compared geochemically with other predominantly continental back arc basins in the aegean sea and bransfield strait all three basins show the presence of a rock phase derived from partial melting of mantle only slightly modified by subduction processes the lakelands facies tholeiites of the jeffers group they all also contain a more differentiated series showing more subduction related chemical characteristics the harrington river facies of the jeffers group geochemical differences between these rocks and typical calc alkali series are related to the lesser role of hydrous fluids in the back arc basins as a result titanomagnetite and amphibole are not important fractionating phases and nb and ta are not significantly depleted

well logging methods in groundwater surveys of complicated aquifer systems bohemian cretaceous basin geophysical well logging methods including borehole flow logging can significantly contribute to a detailed understanding of hydrogeological conditions in basins with complicated sedimentary structure in studies undertaken to make optimal use of water sources or to protect those resources from contamination it is a common practice to delineate geological and hydrogeologic conditions at the scale used in geological maps and surface surveys however there is a need for more detailed descriptions of basin structure for many tasks related to water resources management and hydrologic research this paper presents four specific examples of boreholes in complex hydrogeologic settings where useful information was provided by geophysical logging 1 identification of large scale upward cross flow between aquifer horizons in an open borehole 2 confirmation of continuous permeability throughout a long borehole interval 3 identification of leakage into a test well via a defective casing joint 4 evidence for downward flow in open boreholes and 5 identification of permeable beds associated with water inflows during aquifer tests these borehole geophysical measurements provide important information about the detailed lithological profiles of aquifers especially in the absence of core enabling the optimization of groundwater monitoring resource use and wellhead protection activities

reconnaissance geophysical methods in landslide investigations abstract landslides are a natural hazard in many countries and often affect civil engineering structures and projects three aspects in particular require examination in a geotechnical appraisal of a landslide s stability in engineering terms 1 the definition of its three dimensional shape with particular reference to shear surfaces and failure planes 2 the definition of the hydrogeological regime with regard to water input to the landslide and its distribution within the slip mass 3 the detection of movement by or within the slip mass and the characterisation of such movements the site investigation costs may be very high since landslides may be extremely large structurally complex and topographically severe it is therefore advantageous in suitable circumstances to carry out reconnaissance geophysical surveys to define the structure and to guide optimum siting of boreholes and pits and ultimately the installation of piezometers inclinometers etc standard surface geophysical techniques including the seismic electrical resistivity acoustic emission and borehole methods have all been applied with varying success to look at a landslide before a major site investigation commences in recent years electromagnetic methods have been the subject of considerable research in this field and significant advances have been made in this paper the application of the above geophysical methods at the reconnaissance stage in a landslide investigation has been reviewed and illustrated with several case histories taken from different geological settings

practical techniques for 3d resistivity surveys and data inversion1 techniques to reduce the time needed to carry out 3d resistivity surveys with a moderate number 25 to 100 of electrodes and the computing time required to interpret the data have been developed the electrodes in a 3d survey are normally arranged in a square grid and the pole pole array is used to make the potential measurements the number of measurements required can be reduced to about one third of the maximum possible number without seriously degrading the resolution of the resulting inversion model by making measurements along the horizontal vertical and 45 diagonal rows of electrodes passing through the current electrode the smoothness constrained least squares inversion method is used for the data interpretation the computing time required by this technique can be greatly reduced by using a homogeneous half space as the starting model so that the jacobian matrix of partial derivatives can be calculated analytically a quasi newton updating method is then used to estimate the partial derivatives for subsequent iterations this inversion technique has been tested on synthetic and field data where a satisfactory model is obtained using a modest amount of computer time on an 80486dx2 66 microcomputer it takes about 20 minutes to invert the data from a 7 by 7 electrode survey grid using the techniques described below 3d resistivity surveys and data inversion can be carried out using commercially available field equipment and an inexpensive microcomputer

the analysis of rainfall induced slope failures at iva valley area of enugu state nigeria this paper analyses the dominant mechanisms of slope failures and identifies potential obstacles to landslide hazard reduction at the iva valley area enugu nigeria the landscape is replete with landslide scars and gullies of varied sizes and the slope deposits comprise unconsolidated friable sands inter bedded with thin units of montmorillonitic claystone forty three landslide events were identified in the study area with most being shallow short run out movements with slip surface depth 2 m the study found the landslides mainly occur in the beginning of rainy season characterized by short duration high intensity rainfall an integrated approach comprising field mapping laboratory tests and numerical analyses reveals that the barren nature of the slopes prior to the outset of rainy season high rainfall intensity erosion overgrazing soil characteristics and the site s unique lithologic sequence are the main causes of instability shearing tests under several conditions showed that the soils strongly strain soften until low steady state strength is achieved a computer code based on this strength reduction technique used input parameters obtained from the field and laboratory studies to simulate a landslide with similar structure travel distance and distribution area it is noted that urbanization has gradually increased the vulnerability of the society s poor to landslide hazards as they now erect unplanned residence tents and blocks on the slopes this work is part of a regional study aimed at finding ways of protecting the vulnerable by generating data that could be used to build future landslide susceptibility map

wave setup at river entrances recent observations of elevated water levels in rivers on the coast of southern queensland and northern new south wales are summarised the date from cyclone roger indicates very substantial super elevations of the order 0 5m which cannot be accounted for by fresh water flow wind setup and the inverse barometer effect however the alternative explanation that these overheights be caused by wave setup does not totally agree with detailed measurements obtained from the brunswick river on other occasions more detailed measurements from the field and the laboratory are required to clarify the issue

petrology of upper ordovician lower silurian rocks of the antigonish highlands nova scotia upper ordovician to lower silurian rocks in the antigonish highlands consist of interlayered basalts rhyodacites arkoses and conglomerates overlain by a thick sequence of marine clastic rocks and minor rhyolites the stratigraphy documents a marine transgression the volcanic rocks were deposited in a within plate continental extensional environment the basalts display alkalic and tholeiitic affinities and the rhyodacites were formed by anatexis of the crust the origin of the younger rhyolites is not clear they are compositionally distinct from the rhyodacites but may be related to them as late stage differentiates at present it is not possible to evaluate whether the tectonic setting and magmatic affinities are regionally or locally controlled the geological history is very similar to that of lower silurian rocks immediately north of the antigonish highlands at arisaig in the simplest sense this indicates these areas may have been juxtaposed prior to the late ordovician and limits cumulative

geochemistry of the north mountain basalts nova scotia canada abstract the early mesozoic north mountain basalts of nova scotia canada are continental tholeiites similar in composition to numerous triassic diabase dykes of the northern appalachians all these rocks probably originated during the initial opening of the atlantic ocean the lavas have been affected by zeolite facies metamorphism which caused mobilization of some elements such as li and cu the north mountain basalts underwent extensive fractional crystallization dominated by pyroxene and plagioclase separation compared to oceanic tholeiites these basalts have similar abundances of major rare earth and some high field strength elements and corresponding element ratios but they have higher contents of th and k and associated elements their normalized trace element patterns are closely similar to those of some other continental tholeiites and to the average continental crust and display negative nb anomalies it is suggested that continental tholeiites were derived from an upper mantle source similar to that for oceanic tholeiites but were affected by crustal contamination

2d electrical resistivity imaging of some complex landslides in lucanian apennine chain southern italy we use high resolution electrical resistivity imaging to delineate the geometry of complex landslides in the lucanian apennine chain of southern italy to identify the discontinuity between the landslide material and bedrock and to locate possible surfaces of reactivation the lucanian apennine chain is characterized by high hydrogeological hazard and shows a complete panorama of mass movements in this area all typologies of landslides markedly predisposed and tightly controlled by the geostructural characteristics are found rotational and translational slides rototranslational slides earth and mudflows as well as deep seated gravitational slope phenomena with a predominance of rototranslational slides evolving as earthflow slides three test sites characterized by complex geology and a high hydrogeologic hazard are studied the giarrossa and varco izzo earthflow slides are located to the west and east of the town of potenza whereas the latronico slide is located close to the town of latronico

suspect terranes and accretionary history of the appalachian orogen the north american connection or the grenvillian continental crust that separated from eastern north america during the initiation of the appalachian orogenic cycle is poorly defined within the present orogen a variety of terranes occur outboard of the north american miogeocline all structurally uncoupled and therefore suspect stratigraphic analysis indicates that appalachian accretion progressed from the miogeocline outward the boundaries of the earliest accreted western terranes are marked by melange and ophiolite complexes later boundaries between eastern terranes are steep mylonitic zones and brittle faults accretionary events defined by stratigraphic analysis correspond to times of major deformation plutonism and metamorphism in the history of the orogen

monitoring landslides with geophysical and geodetic observations the objective of this study was to evaluate and predict land movement by integrating geodetic geophysical and meteorological data in a landslide area specifically electrical resistivity tomography surveying global navigation satellite system and terrestrial laser scanning techniques were integrated to monitor a landslide the study area lies to the southeast of the town of taskent in southern turkey close to balcilar in the central taurus mountain chain landslides result in considerable damage to structures farmland and the environment in this area therefore it is important to characterise the size extent and timing of past land movements in order to mitigate damage from future landslides analysis presented in this paper shows that the greatest land movements in the region occur in spring when average motions can be up to 1 5 m per month it is demonstrated that integrated techniques provide a better means for monitoring landslide processes and gathering data for predictions of future movements mapping landslide movements by integrating geophysical and geodetic observations can provide a meaningful evaluation of a landslide and its dynamics