detection of illegal mine voids using electrical resistivity tomography the case study of raniganj coalfield india abstract unauthorised coal mining activities may result in development of hidden hollows rat holes galleries goafs shafts etc which pose great threats of land subsidence fire water flooding leading to severe environmental hazards health problems and safety issues to the local people present study deals with delineation and mapping of unauthorised coal mine voids galleries over an abandoned old mine around khudia open cast mine nirsa raniganj coalfield india electrical resistivity tomography ert study comprising wenner schlumberger dipole dipole and gradient arrays has been carried out along three parallel profiles over the affected area further joint inversion of all combined arrays has also been carried out using 2 5d resistivity inversion program to combine the relative advantages of all the arrays for producing superior results 2d ert sections have been generated for the filtered data sets with a constant quality factors and two different current thresholds the best results have been obtained from joint inversion of all combine arrays for the filtered data with higher current threshold the observed resistivity anomalies are well correlated with the depth of coal seam occurrences as observed in the borehole litholog of nearby area finally a geoelectric model of four unauthorised coal mine galleries has been established with their extension and orientation over the study area the results demonstrate the suitability of the ert technique through joint inversion of all combined arrays for characterization of illegal coal mine workings

characterization of shallow karst using electrical resistivity imaging in a limestone mining area the guangxi area is famous for its high degree of karstification due to a long period of groundwater erosion and the development of fracture networks karst collapse appeared during the mining process and caused many environmental problems applying electrical resistivity imaging eri is the most cost effective method to study the characteristic of the subsurface karst environment in this area more than 24 km of eri profiles around a mining area is carried out to present the development of karst which will be used to evaluate the effects on the ground water and the surrounding environment the area represents a classical limestone rock which is of high quality and is used for cement production in this study the eri is used to determine the geometry of the karst range at depth the results are in good agreement with drilling experiments the eri survey provided near surface resistivity information which is very useful for establishing the geometry and the position of potential karst

comparison of geoelectrical imaging and tunnel documentation at the hallandsas tunnel sweden article i nfo for construction in rock a thorough pre investigation is important in order to avoid unforeseen conditions which may delay the work it is crucial to remember the results from this investigation in the further work and use the experience from the construction to update the geological prognosis and reduce the uncertainties different geophysical methods have proved valuable tools in such investigations in this work the electrical imaging is evaluated with regards to the method s applicability the evaluation is done qualitatively by comparing the electrical imaging with tunnel documentation from a tunnel in southern sweden by evaluating the result continuously when making the tunnel a more detailed geological prognosis can be compiled and used in the continued work with the tunnel the parameters used for the comparison are lithology q rqd weathering and water leakage the result was that virtually every change in electrical resistivity image coincides with a change in rock conditions the general trend was that high resistivity corresponded with good quality gneiss whereas low resistivity corresponds to poor quality rock e g high weathering low rqd low q and or several lithological contacts the intermediate resistivity is often amphibolites or rock with water bearing fractures the results were supported by in situ resistivity measurements inside the tunnel and resistivity logging in a core drilling geoelectrical imaging proved to give valuable information for a detailed geological model which could be compiled for a section where the tunnel had not yet been drilled as a help for planning of the continued tunnel work as is the case other geophysical methods it is clear that for the interpretation of data a priori information about the geological setting is necessary

modelling the hydrogeochemical evolution of mine water in a decommissioned opencast coal mine abstract a method for the geochemical modelling of transient contaminant release from rehabilitated opencast coal mines including calibration against existing data is proposed the need for such a methodology is illustrated by a directive received by a decommissioned opencast coal mine in mpumalanga south africa groundwater monitoring data geochemical analyses numerical flow modelling and geochemical modelling are used to model the hydrogeochemical evolution of mine water over time models presented in this study are based on a conceptual model detailing groundwater levels and flow directions hydraulic conductivities groundwater chemistry precipitation evaporation surface water bodies and potential sources additional to this mineralogical analyses leaching tests and acid base accounting were performed to obtain a better understanding of the site geochemistry a geochemical model was constructed which was used to obtain a statistically representative mineral assemblage based on laboratory data which was calibrated against leaching test data this assemblage was simulated in field conditions as input to a numerical flow and transport model the transport of sulfate was modelled accordingly and sulfate concentrations from monitoring data were used for chemical calibration following this long term contaminant release was simulated calibration graphs from the transport model indicated concentrations within a 20 mg l error margin showing that the proposed methodology can be used to calculate contaminant concentrations in an aquifer over time within an acceptable range this approach could provide an improved estimate of the duration of the first flush which upon completion will transform decommissioned collieries into large scale reservoirs of utilisable groundwater

geochemistry of surface and ground water in guiyang china water rock interaction and pollution in a karst hydrological system the chemical compositions of the surface ground water of guiyang the capital city of guizhou province china are dominated by ca2 mg2 hco3 andso42 which have been derived largely from chemical weathering of carbonate rocks limestone and dolomite the production of so42 has multiple origins mainly from dissolution of sulfate evaporites oxidation of sulfide minerals and organic s in the strata and anthropogenic sources most ground water is exposed to soil co2 and therefore the h2co3 which attacks minerals contains much soil c in addition the h2so4 produced as a result of the oxidation of sulfides in s rich coal seams and or organic s is believed to be associated with the chemical weathering of rocks the major anthropogenic components in the surface and ground water include k na cl so42 andno3 with cl and no3 being the main contributors to ground water pollution in guiyang and its adjacent areas the seasonal variations in concentrations of anthropogenic components demonstrate that the karst ground water system is liable to pollution by human activities the higher content of no3 in ground water compared to surface water during the summer and winter seasons indicates that the karstic ground water system is not capable of denitrification and therefore does not easily recover once contaminated with nitrates

subsurface cavity detection over patherdih colliery jharia coalfield india using electrical resistivity tomography the present study deals with delineation and mapping of subsurface voids which are very common around the patherdih colliery of jharia coal field india these are caused by coal fire and old unplanned illegal mining activity initially a conceptual model of void formation associated with coal fire has been proposed the burning of coal leads to the void formation due to volume reduction because of transformation of coal to ashes it is supposed to have significant resistivity contrasts between bedrock i e mainly sandstone clay stone shale etc and void space which are filled with ashes generated from burned coal seam field situations have been simulated through forward modeling and the data generated by gradient and dipole dipole arrays have been corrupted by 5 noise the simulations have been carried out for two voids with varied resistivity the inversions of the data for both the arrays bring up the dimension of the void within reasonable accuracy unlike its resistivity in fact the considered resistive void seems to be a conducting void in the present study data have been collected by a state of the art flashres universal electrical resistivity tomography ert instrument which have 61 channel and 64 electrode data acquisition capacity ert sections have been generated over two profiles using wenner schlumberger gradient dipole dipole and joint inversion of all combine arrays different resistive anomalous features with resistivity of about 300 200 m have been delineated in both profiles these are associated with voids at the depths of about 23 25 and 45 54 m generated by burning of coal seams xiva and xiv respectively the obtained results are in broad agreement with the available litholog and surface manifestation of coal fire the results prove the efficacy of the ert technique for detection of voids associated with coal fire

integrated high resolution geophysical investigations as potential tools for water resource investigations in karst terrain karstic aquifers can be particularly vulnerable to both pollution from surface activities and large scale dewatering from mineral winning operations this is because of the enhanced vertical and lateral flow paths resulting from the dissolution of carbonate species by rainfall often this process results in the development of voids that can range in size from several centimetres to several tens of metres to date groundwater vulnerability maps for england and wales including karst areas have been produced using a methodology that does not consider the presence of karst features the uncertainties that are presented by the potential for pollution by the presence of water carrying conduits in karst areas where there are proposed or existing limestone quarries require new techniques for detecting and delineating underground cave systems in order for any mapping technique to provide an acceptable assessment of vulnerability the location and spatial distribution of high permeability flow paths need to be established of the available geophysics techniques that may allow for the identification of such features microgravity and resistivity imaging are likely to be the most successful microgravity surveying has the potential to identify the presence and location of such voids and with the integration of electrical tomographic work can provide targets for the location of monitoring boreholes whilst these techniques are intensive and may not be cost effective on a regional scale they do have the potential to provide high resolution data over smaller areas which would be invaluable to any site or area specific assessment of vulnerability

a numerical comparison of 2d resistivity imaging with 10 electrode arrays numerical simulations are used to compare the resolution and efficiency of 2d resistivity imaging surveys for 10 electrode arrays the arrays analysed include polepole pp pole dipole pd half wenner hw wenner wn schlumberger sc dipole dipole dd wenner wb array gm multiple or moving gradient array gd and midpoint potential referred measurement mpr arrays five synthetic geological models simulating a buried channel a narrow conductive dike a narrow resistive dike dipping blocks and covered waste ponds were used to examine the surveying efficiency anomaly effects signal to noise ratios and the imaging capabilities of these arrays the responses to variations in the data density and noise sensitivities of these electrode configurations were also investigated using robust l1 norm inversion and smoothness constrained least squares l2 norm inversion for the five synthetic models the results show the following i gm and wn are less contaminated by noise than the other electrode arrays ii the relative anomaly effects for the different arrays vary with the geological models however the relatively high anomaly effects of pp gm and wb surveys do not always give a high resolution image pd dd and gd can yield better resolution images than gm pp wn and wb although they are more susceptible to noise contamination sc is also a strong candidate but is expected to give more edge effects iii the imaging quality of these arrays is relatively robust with respect to reductions in the data density of a multi electrode layout within the tested ranges iv the robust inversion generally gives better imaging results than the l2 norm inversion especially with noisy data except for the dipping block structure presented here v gd and mpr are well suited to multichannel surveying and gd may produce images that are comparable to those obtained with dd and pd accordingly the gd pd dd and sc arrays are strongly recommended for 2d resistivity imaging where the final choice will be determined by the expected geology the purpose of the survey and logistical considerations

hydrogeochemical processes governing the origin transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters abstract the formation of acid mine drainage from metals extraction or natural acid rock drainage and its mixing with surface waters is a complex process that depends on petrology and mineralogy structural geology geomorphology surface water hydrology hydrogeology climatology microbiology chemistry and mining and mineral processing history the concentrations of metals metalloids acidity alkalinity cl f and so 4 2 found in receiving streams rivers and lakes are affected by all of these factors and their interactions remediation of mine sites is an engineering concern but to design a remediation plan without understanding the hydrogeochemical processes of contaminant mobilization can lead to ineffective and excessively costly remediation furthermore remediation needs a goal commensurate with natural background conditions rather than water quality standards that might bear little relation to conditions of a highly mineralized terrain this paper reviews hydrogeochemical generalizations primarily from us geological survey research that enhance our understanding of the origin transport and fate of contaminants released from mined and mineralized areas mobility of potential or actual contaminants from mining and mineral processing activities depends on 1 occurrence is the mineral source of the contaminant actually present 2 abundance is the mineral present in sufficient quantity to make a difference 3 reactivity what are the energetics rates and mechanisms of sorption and mineral dissolution and precipitation relative to the flow rate of the water and 4 hydrology what are the main flow paths for contaminated water estimates of relative proportions of minerals dissolved and precipitated can be made with mass balance calculations if minerals and water compositions along a flow path are known combined with discharge these mass balance estimates quantify the actual weathering rate of pyrite mineralization in the environment and compare reasonably well with laboratory rates of pyrite oxidation except when large quantities of soluble salts and evaporated mine waters have accumulated underground quantitative mineralogy with trace element compositions can substantially improve the identification of source minerals for specific trace elements through mass balances post dissolution sorption and precipitation attenuation reactions depend on the chemical behavior of each element solution composition and ph aqueous speciation temperature and contact time with mineral surfaces for example little metal attenuation occurs in waters of low ph

identifying hydrologic flowpaths on arctic hillslopes using electrical resistivity and self potential shallow subsurface flow is a dominant process controlling hillslope runoff generation soil development and solute reaction and transport despite their importance the location and geometry of these flow paths are difficult to determine in arctic environments shallow subsurface flow paths are limited to a thin zone of seasonal thaw above permafrost which is traditionally assumed to mimic the surface topography we have used a combined approach of electrical resistivity tomography ert and self potential sp measurements to map shallow subsurface flow paths in and around water tracks drainage features common to arctic hillslopes ert measurements delineate thawed zones in the subsurface that control flow paths whereas sp is sensitive to groundwater flow we have found that areas of low electrical resistivity in the water tracks were deeper than manual thaw depth estimates and varied from the surface topography this finding suggests that traditional techniques might underestimate active layer thaw and the extent of the flow path network on arctic hillslopes sp measurements identify complex 3d flow paths in the thawed zone our results lay the groundwork for investigations into the seasonal dynamics hydrologic connectivity and climate sensitivity of spatially distributed flow path networks on arctic hillslopes

pleistocene terraces of the vltava river in the budějovice basin southern bohemian massif new insights into sedimentary history constrained by luminescence data abstract we studied quaternary sediments from the bud jovice basin in southern bohemia now being able to reconstruct the landscape formation of this area during the late pleistocene the main objective of this study was to map fluvial terraces of the rivers vltava and malse in the basin and to constrain their ages by luminescence dating topographic data from a high resolution dem in combination with lithological profiles of more than 1000 boreholes allowed identifying five terrace levels bb 1 to bb 5 with bases ranging from 7 m below to 26 m above the recent mean water level of the vltava river for the lowermost terrace level bb 1 a consistent stratigraphy with ages ranging between 84 5 9 0 ka and 7 9 0 8 ka was constrained additionally we obtained luminescence ages of alluvial fan and colluvial deposits which allow us to better constrain the late pleistocene sedimentation history of the study area based on the spatial distribution of derived ages the terrace level bb 1 represents a complex sediment body incorporating more distinct packages of river aggradation the presence of stacked fluvial deposits of pleistocene age underneath the recent floodplain points to an ongoing subsidence or relative tectonic stability of the bud jovice basin during the late pleistocene

delineation of fracture zone for groundwater using combined inversion technique this paper deals with severe issue of groundwater crisis over a part of hard rock terrain in the premises of central institute of mining and fuel research cimfr dhanbad jharkhand india the goal of this study is delineation and mapping of fractured rock mass for groundwater exploration generally fractured rock formation is the only source of groundwater in hard rock terrain electrical resistivity tomography ert survey was conducted along three profiles over different parts of cimfr premises using wenner schlumberger and dipole dipole arrays combined inversion of both arrays has been carried out during data analysis for better delineation of fracture rock masses in the complex geological environment two water saturated fracture zones have been identified for the availability of groundwater which has been confirmed by direct borehole drilling this proves the effectiveness of ert survey by combined inversion of both arrays for delineation of fracture zones

combined electrical resistivity imaging and ground penetrating radar study for detection of buried utilities in federal university of agriculture abeokuta nigeria the knowledge of the exact location and depth of buried utility such as pipes assists greatly for prevention of accidents and wastage of resources this study addresses the application of integrated geophysical methods for detections of buried utility in student s residential hostels federal university of agriculture abeokuta southwestern nigeria the goals of the surveys are to determine the effectiveness of the applied methods in detection of buried utilities locations and their depths as well as verification of obtained depths to the top of target by excavation method 2d electrical resistivity imaging eri using wenner array with electrode separation ranging from 0 25 to 1 25 m and ground penetrating radar gpr survey using a common offset profiling and center frequency of 400 mhz were carried out along ten traverses in the study area the field data were processed using res2dinv and radan 7 softwares for resistivity and gpr data respectively inverted resistivity sections and radar images generated information up to a depth of 0 80 m and 3 00 m respectively the position size and depth of buried pipes cannot be determined precisely by ert compared to gpr survey the depths to the top of buried pipes by ert ranges from 0 20 to 0 46 m while the gpr measured depths ranged from 0 16 to 0 55 m from the surface integrated interpretation showed that gpr can effectively provide information about locations and depths to the top of buried pipes with a higher precision than ert method comparisons of measured gpr depths with in situ verification using excavation method correlate fairly well

identification of hydrogeochemical processes and pollution sources of groundwater resources in the marand plain northwest of iran the main aims of the present study are to identify the major factors affecting hydrogeochemistry of groundwater resources in the marand plain nw iran and to evaluate the potential sources of major and trace elements using multivariate statistical analysis such as hierarchical clustering analysis hca and factor analysis fa to achieve these goals groundwater samples were collected in three sampling periods in september 2013 may 2014 and september 2014 and analyzed with regard to ions e g ca2 mg2 na and k hco3 so4 2 cl f and no3 and trace metals e g cr pb cd mn fe al and as the piper diagrams show that the majority of samples belong to na cl water type and are followed by ca hco3 and mixed ca na hco3 cross plots show that weathering and dissolution of different rocks and minerals ion exchange reverse ion exchange and anthropogenic activities especially agricultural activities influence the hydrogeochemistry of the study area the results of the fa demonstrate that 6 factors with 81 7 of total variance are effective in the overall hydrogeochemistry which are attributed to geogenic and anthropogenic impacts the hca categorizes the samples into two clusters samples of cluster c1 which appear to have higher values of some trace metals like pb and as are spatially located at the eastern and central parts of the plain while samples of cluster c2 which express the salinization of the groundwater are situated mainly westward with few local exceptions

actual extension of sinkholes considerations about geophysical geomorphological and field inspection techniques in urban planning projects in the ebro basin ne spain abstract aerial photographs historical cartographies and field inspection are useful tools in urban planning design on mantled karst because they permit a wide time interval to be analyzed in the case of zaragoza city several works have confirmed the interest of these approaches in configuring the urban planning code and therefore represent a promising technique nevertheless some caveats should be taken into account when using this kind of information a detailed analysis is presented comparing in a case study from the surroundings of zaragoza geomorphological historical analysis and field inspection with geophysical data field inspection in a noncultivated area permits the constraint of the presence of karst indicators below the geomorphological resolution of aerial photographs and shows results consistent with geophysical surveys the studied case shows an inner zone coinciding with the sinkhole mapped from aerial photographs that correlates with changes in the position of the substratum and changes in thickness of alluvial sediments the integrated analysis permits us to define an external subsidence ring around the geomorphological sinkhole whose surface is twice the size of the inner zone this outer ring is indicated by geometrical changes in gpr profiles increases of thickness of the conductive shallower unit toward the collapse and small collapses on marginal cracks these results support the higher extension of karst hazards linked to sinkholes with respect to their geomorphological expression and the needed detailed analysis to constrain the real sinkhole size or the use of security radii surrounding this surficial evidence when geomorphological data is used for the hazard analyses or the urban planning at karstic zones

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

control of coal facies to adsorption desorption divergence of coals a case from the xiqu drainage area gujiao cbm block north china abstract adsorption and desorption of coal to methane are substantially related to coal facies referring to the production potential of a coalbed methane cbm well based on analyses of the stratified channel samples from coal seams no 2 no 4 and no 9 in the xiqu drainage area gujiao cbm block north china the relationship between coal facies and adsorption desorption behaviors was first proposed and discussed using the coal facies diagrams suggested by previous investigators four types of coal facies were distinguished in the coal seams including the upper delta plain wet forest swamp i the lower delta plain fen ii the lower delta plain marsh iii and the back barrier low moor iv the upper delta plain wet forest swamp occurred dominantly developing at the bottom and top of all the coal seams both the ash yield and groundwater index gwi tend to increase from coal facies i to iv whereas the volatile compounds fixed carbon organic sulfur total sulfur micropore volume and specific surface area tissue preservation index tpi and vegetation index vi decreased which indicates changes in the vegetation types water supplements and disturbance acid base properties and redox conditions in the paleomires paleomire evolution accompanied the rise and drop of the sea level with a transgression or regression process that could be represented by the coal facies sequence coal seams no 2 no 4 and no 9 were discriminated into two three and two evolving stages respectively and these stages were characterized by complete cycles except stage 4 i from the lower delta plain marsh mudstone partings in the coal seams deposited during the highest sea level collectively paleomire environments especially the variation of vegetation types and mire water condition result in adsorption and desorption divergences among different coal facies arborescent plants decrease from coal facies i to iv as the hydrodynamic intensity increases leading to corresponding changes in botanical tissue preservation medium oxidizability mineral content and ultimately adsorption and desorption behaviors in view of the gas content and desorption capacity of the coal layers in the same coal seam the layers from the upper delta plain wet forest swamp may have the best potential for cbm drainage followed by those from the lower delta plain fen and marsh while those from the back barrier low moor may have the worst potential

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

electrical resistivity and seismic refraction tomography to detect buried cavities near surface cavities can pose serious hazards to human safety especially in highly urbanized town centres the location of subsurface voids the estimation of their size and the evaluation of the overburden thickness are necessary to assess the risk of collapse in this study electrical resistivity tomography ert and seismic refraction tomography data are integrated in a joint interpretation process for cavity location in the city of rome ert is a well established and widely employed method for cavity detection however additional information provided by seismic refraction tomography is capable of eliminating some potential pitfalls in resistivity data interpretation we propose that the structure of the cavities defined by ert can be used as a base to optimize seismic refraction tomography investigations within the framework of a joint interpretation process data integration and the insertion of a priori information are key issues for reducing the uncertainties associated with the inversion process and for optimizing both acquisition procedures and computation time herein the two geophysical methods are tested on both synthetic and real data and the integration of the results is found to be successful in detecting isolated cavities and in assessing their geometrical characteristics the cavity location inferred by geophysical non invasive methods has been subsequently confirmed by direct inspection

comparison of gpr 2d resistivity and traditional techniques for the subsurface exploration of the oschingen landslide swabian alb germany abstract numerous rotational and translational slides of different sizes cause considerable economic damage in the swabian alb sw germany and are a challenge for risk assessment the oschingen landslide is a typical example for landslides occurring along the escarpment lithology consists of jurassic sedimentary rocks involving clays overlain by marls and limestones a combination of traditional methods drilling mapping inclinometers and geophysical techniques 2d resistivity ert ground penetrating radar gpr was applied to gain knowledge about the thickness and internal structure of the landslide the drillings and penetration tests provided point information on landslide extent structure and material involved in general all inclinometers showed very little movement if at all the gpr results were affected by strong signal attenuation and by overhead reflections from the nearby woods despite these general obstacles for the application of gpr on landslides near surface sediment structures were detected in the 2d resistivity sections higher resistive limestone blocks reaching 10 15 m in thickness could be clearly distinguished from the underlying bedrock the detailed two dimensional data of the electrical resistivity tomography ert along with the rather high survey speed turned out to be the best choice to gain detailed spatial information on thickness and extent of the slope movement the measured profiles coincide with the gpr data and correspond to borehole data surprisingly all results from the applied methods clearly detected the absence of large landslide blocks in the north west of the study area this finding could not be concluded from local geomorphology of this area regarding the current landslide displacement derived from the inclinometer measurements the large landslide blocks seem to be dormant during the measured period

determining the factors controlling the chemical composition of groundwater using multivariate statistics and geochemical methods in the xiqu coal mine north china studying the hydrogeochemical processes that control groundwater quality in different aquifers helps to identify the sources of inrush water into coal mines in this paper 65 mine water samples were collected from xiqu coal mine during 2016 and 2017 to determine the hydrogeochemical processes and controlling factors of mine water using hydrochemical methods and multivariate statistical analysis the mine water is acidic to alkaline in nature the dominant anions in the mine water are so42 and hco3 and cations were dominated by ca2 na and mg2 the dominant hydrochemical facies of groundwater were so4 na ca and so4 ca mg water types based on multivariate statistical analysis four principal components and two clusters were obtained concentrations of so42 showed significant positive correlations with ca2 mg2 fe2 and fe3 and strong negative correlations with hco3 and ph the mine water chemistry was dominated by the oxidation of iron bearing sulfide minerals cation exchange and the dissolution of silicate carbonate and sulfate minerals in addition human activities such as agriculture are also likely to have influences groundwater chemistry at the mine site

detection of underground cavities by combining gravity magnetic and ground penetrating radar surveys a case study from the zaragoza area ne spain a geophysical survey routine is proposed to detect underground cavities and dolines it is based on the sequential application of magnetic low frequency ground penetrating radar gpr and microgravity techniques a case study near zaragoza ebro valley spain demonstrates the applicability of these methods the strong contrast of magnetic and electromagnetic properties and to a lesser scale of density between the doline filling and the surrounding stratified tertiary and quaternary rocks allows the shape of filled cavities to be clearly outlined by these methods

ground penetrating radar geologic field studies of the ejecta of barringer meteorite crater arizona as a planetary analog 1 ground penetrating radar gpr has been a useful geophysical tool in investigating a variety of shallow subsurface geological environments on earth here we investigate the capabilities of gpr to provide useful geologic information in one of the most common geologic settings of planetary surfaces impact crater ejecta three types of ejecta are surveyed with gpr at two wavelengths 400 mhz 200 mhz at meteor crater arizona with the goal of capturing the gpr signature of the subsurface rock population in order to ground truth the gpr characterization subsurface rocks are visually counted and measured in preexisting subsurface exposures immediately adjacent to and below the gpr transect the rock size frequency distribution from 10 to 50 cm based on visual counts is well described by both power law and exponential functions the former slightly better reflecting the control of fragmentation processes during the impact ejection event gpr counts are found to overestimate the number of subsurface rocks in the upper meter by a factor of 2 3x and underestimate in the second meter of depth 0 6 1 0x results attributable to the highly scattering nature of blocky ejecta overturned ejecta that is fractured yet in which fragments are minimally displaced from their complement fragments produces fewer gpr returns than well mixed ejecta the use of two wavelengths and division of results into multiple depth zones provides multiple aspects by which to characterize the ejecta block population remote gpr measurement of subsurface ejecta in future planetary situations with no subsurface exposure can be used to characterize those rock populations relative to that of meteor crater