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Mass movements in wavy topographic zones pose a constant danger to infrastructure, water management, plantation formation, and human life. A commonly used method in near-surface geophysical surveys is Electrical Resistivity Tomography (ERT) to define various strata levels and calculate the likely slip surface of landslides. We use a developed algorithm named ResIPy to be able to incorporate surface topography using triangular cells in finite element forward and inversion processes. Initially, a synthetic landslide case demonstrates that employing the triangular mesh results in more accurate identification of the geological formations than the rectangular mesh, which requires more CPU time. Then, field data from a prone landslide at approximately 20 km NW of the Tehran province, in Iran, was investigated using eight geoelectrical profiles spaced 20 m along the sliding surface accompanying one borehole. The sliding surface corresponds to a deep zone with low resistivity due to the presence of shale, and the sliding material is composed of gravelly soil, silt, and tuff. According to the field observations, the crown portion is vulnerable to sliding because there are transverse cracks in the uphill slope. [ABSTRACT FROM AUTHOR]

This paper describes the usage of fuzzy knowledge based method to integrate various geophysical data in order to prepare Mineral Prospectivity Map (MPM). Different geophysical layers which are derived from magnetic and electrical surveys are used to evaluate Seridune copper deposit located in the Kerman province of Iran. Since, electrical layers involving resistivity, induced polarization and metal factor, in comparison with layers derived from magnetic survey, are more important in porphyry copper exploration, fuzzy Analytical Hierarchy Process (AHP) is used to determine the weights belonged to each of them. Four layers which are derived from magnetic data involving upward continuation, analytic signal, reduced to pole and pseudo gravity are considered in this study. Three geoscientists who are expert in geophysical prospecting are used to implement fuzzy AHP. After determination of the normalized weights of the seven evidential layers as main criteria, fuzzy operators are applied to integrate different layers. To evaluate the result of the approach, drilled boreholes are used to validate final MPM. By considering a borehole which is belonged to the suggested area for drilling, a satisfactory result was obtained. The proposed method can be a useful approach for integrating various geodata sets for MPM. [ABSTRACT FROM AUTHOR]

This paper describes usage of the Normalized Full Gradient (NFG) method to selfpotential (SP) data. It can be used to estimate location, depth to the top, and center of the deposit. One of the important parameters to estimate, the accurate shape of the deposit, is true selection of the harmonic number. In this paper, the correct harmonic number is determined by the trial-and-error method, and then this method would be tested for noisecorrupted synthetic data. As a consequence of using the NFG method to anomalies of simple geometric-shaped models including vertical sheet and inclined sheet, the underground structures are found very close to their actual locations. In order to see the capability of the method to localize multi-object simultaneously, the NFG method could accurately indicate location of both constructed structures along a profile. Subsequently, reasonable results are acquired after corrupting the anomalies with noise. Finally, the NFG is applied to SP data from a galena deposit located in the NW of Iran, Khalf village. Geological interpretation of the study area confirmed occurrence of a Galena vein. The vein deposit can be simulated by a simple sheet model. After implementation of the method, a general view of the deposit structure is obtained and it helped us to get a fast interpretation. Final result of this method showed that the deposit began from the surface to approximately less than 50 m. [ABSTRACT FROM AUTHOR]

In projects involving reserves estimation, a principal aim is to reduce the variance of the estimation and related uncertainty. This requires extensive and costly drilling. Among the variety of geostatistical-based techniques used to reduce the variance of the estimation in mineral reserves modelling, multivariate geostatistical methods can be appropriate tools when a sparse pattern of drilling boreholes exist. The present work introduces collocated cokriging and kriging with an external drift as multivariate geostatistical methods to incorporate sulphide factor as a secondary correlated variable to estimate Cu grade distribution. The study area is one of the potential zones of porphyry Cu occurrences, located in the Kerman province of southern Iran. To estimate the Cu grade distribution in this region, sulphide factor data as a dense correlated geophysical variable with the primary variable was used because this incurs less cost than drilling holes. Application of these multivariate geostatistical techniques to a specific exploration such as Seridune Copper Deposit in interpolating Cu grade measurements (primary data) using weakly correlated sulphide factor (secondary data) suggests that when Cu grade is undersampled, the secondary data can contribute substantially to identifying primary data. The results show that incorporating a secondary variable leads to better results than ordinary kriging (as a univariate method) that does not incorporate sulphide factor data. The validation of leave-out samples was used to compare the performance of the methods. Based on mean absolute error, root mean square error and the correlation coefficient of the observed and estimated values, the methods of the collocated cokriging and the kriging with an external drift outperformed grade estimation in comparison with ordinary kriging. [ABSTRACT FROM AUTHOR]