Applied Geophysics

The Very Low Frequency Electromagnetic (VLF-EM) method, which enables surveying without contact with the ground, is suitable for ground surveys in a wide area and has been used in mapping geology and in mineral exploration for decades. The technique makes use of signal radiation from military navigation radio transmitters operating in the frequency range of 15-30 kHz. When the electromagnetic wave impinges on the surface it is both reflected back into the air and refracted into the earth. By measuring the shifted reflected magnetic field relative to the primary field, subsurface structures can be constrained. Freely and readily available primary signals anywhere around the earth make the VLF method very convenient and efficient for field data collection. Further, VLF data processing using digital linear filtering is quite accurate and very efficient in depicting the qualitative information about subsurface conductors, even though quantitative interpretation of VLF data is as complex as other EM data interpretation. In this study, various aspect of VLF-EM method such as basic theory, worldwide VLF transmitters, and quantities measured and a case study review of the integrated geophysical exploration for sulphide minerals In the Wadi Sa'al area, south Sinai in Egypt (only the VLF-EM method used in this study were review).

This paper presents the results of the application of the Ground Penetrating Radar (GPR) method, or Georadar, in outlining a zone of contamination due to solid residues at the waste burial site of Rio Claro in the state of São Paulo, SE Brazil. A total of eight GPR profiles with 50-and 100-MHz antennae were surveyed. Six profiles were located within the landfill site and the remaining two were outside. The main objective of the GPR survey was to evaluate the side extension of contamination. A Vertical Electric Sounding (VES) survey was performed at four points within the site in order to investigate the vertical extent of the contamination plume and to define the bottom of the landfill. Two additional VESs were done outside the landfill with the purpose of determining the top of the ground water table and the geoelectric stratigraphy of the background. From the interpretation of the GPR profiles, it was possible to locate the top of the contamination plume and to infer that it was migrating laterally beyond the limits of the waste disposal site. This was observed along the profile situated close to the highway SP-127, which was about 20 m from the limit of the site. The signature of the contaminant appears as a discontinuous reflector that is believed to be a shallow ground water table. The discontinuity is marked by a shadow zone, which is characteristic of conductive contaminant residues. The contamination did not move far enough to reach a sugar cane plantation located at approximately 100 m from the border of the site. In the regions free from contamination, the ground water table was mapped at approximately 10 m of depth, and it was characterized by a strong and continuous reflector. The radar signal penetrated deep enough and enabled the identification of a second reflector at approximately 14 m deep, interpreted as the contact between the Rio Claro and the Corumbataí formations. The contact is marked by the presence of gravel characterized by ferruginous concretes, which cause the strong amplitude reflection in the GPR profile. Within the landfill site, the quantitative interpretation of the VES results showed the contamination zone. The base of the landfill varies between 11 and 15 m deep. Outside the landfill site, the VES results showed no indication of contamination and allowed the determination of the top of the ground water table and the contact between the Rio Claro and the Corumbataí formations. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology and information from several boreholes, about 17 m depth, on average. The bottom of the landfill reaches a maximum of 14.5 m depth. D

In elastic wave forward modeling, absorbing boundary conditions (ABC) are used to mitigate undesired refl ections from the model truncation boundaries. The perfectly matched layer (PML) has proved to be the best available ABC. However, the traditional splitting PML (SPML) ABC has some serious disadvantages: for example, global SPML ABCs require much more computing memory, although the implementation is easy. The implementation of local SPML ABCs also has some diffi culties, since edges and corners must be considered. The traditional non-splitting perfectly matched layer (NPML) ABC has complex computation because of the convolution. In this paper, based on non-splitting perfectly matched layer (NPML) ABCs combined with the complex frequency-shifted stretching function (CFS), we introduce a novel numerical implementation method for PML absorbing boundary conditions with simple calculation equations, small memory requirement, and easy programming.

The goal of cathodic protection is to prevent corrosion by maintaining buried pipelines at a constant potential with respect to the surrounding soil. In practice, however, the implementation is very complicated since many factors can contribute to the current flowing off the pipe. Design requires characterization of the parameters impacting the corrosion process, such as soil resistivity, size of the pipe and quality of the coating.

A number of lode-gold occurrences are hosted by hydrothermally altered greenstones along the southern boundary of the Palaeoproterozoic Central Lapland Greenstone Belt. The hydrothermally altered and mineralised zones are related to a major thrust and shear zone system that extends much across northern Finland. Spatial correlation between mineralized zones, brittle structural features and chemical alteration was explored and identified from high-resolution aeromagnetic data, in combination with airborne electromagnetic and gamma-ray spectrometric data and coupled with petrophysical and palaeomagnetic studies. The most prominent magnetic, ductile signatures formed during the Svecofennian Orogeny (1900-1800 Ma), resulting in elastic, curved, continuous magnetic patterns. These elastic anomaly patterns were disturbed by tectonic stress from S-SW, resulting in parallel, regularly oriented fracture families and thrust faults normal to the main stress direction. According to aeromagnetic, palaeomagnetic and structural evidence, the thrust zone was active during the latest stage of the orogenic event, but was also reactivated at a later date. Airborne gamma-ray data reveals zones of potassic alteration in the ultramafic rock units in the vicinity of cross-sections of these two fault sets. Chemical and mineralogical changes during alteration and metamorphism strongly affected the mafic and ultramafic host rocks throughout the deformation zone. The strong potassium enrichment and coinciding destruction of magnetic minerals resulted in enhanced potassium concentration and reduction of magnetic anomaly amplitudes. Palaeomagnetic results indicate that the remanent magnetization for the altered ultramafic rocks along the thrust zone is of chemical origin (CRM) and was acquired at 1880-1840 Ma, which is presumed also to be the age of the chemical alteration related to gold mineralization.

Levees are civil engineering structures built to protect human lives, property, and agricultural lands during flood events. To keep these important structures in a safe condition, continuous monitoring must be performed regularly and thoroughly. Small rodent burrows are one of the major defects within levees; however, their early detection and repair helps in protecting levees during flooding events. A set of laboratory experiments was conducted to analyze the polarity change in GPR signals in the presence of subsurface voids and water-filled cavities. Ground Penetrating Radar (GPR) surveys using multi frequency antennas (400 MHz and 900 MHz) were conducted along an 875 meter section of the Lollie Levee near Conway, Arkansas, USA, to assess the levee's structural integrity. Many subsurface animal burrows, water-filled cavities, clay clasts, and metallic objects were investigated and identified. These anomalies were located at different depths and have different sizes. To ground truth the observations, hand dug trenches were excavated to confirm several anomalies. Results show an excellent match between GPR interpreted anomalies and the observed features. In-situ dielectric constant measurements were used to calculate the feature depths. The results of this research show that the 900 MHz antenna has more advantages over the 400 MHz antenna.

A Valley of Mummies was discovered recently by an Egyptian team at Bahariya Oasis, located about 380 km west of the pyramids. Four tombs were excavated, and inside them were found one hundred and five mummies (105), many of them beautifully gilded. These mummies, many sumptuously decorated with religious scenes, are the very best Roman-Period mummies ever found in Egypt. These remains are around 2000 years old, but they are in remarkable condition. A Ground-Penetrating Radar (GPR) had proved successful in detecting the cavities in resistive soil in which the mummies were found.The GPR survey conducted near the earlier-discovered tombs at Kilo-6 El-Bahariya to Farafra Oasis road is the focus of this paper. The GPR survey was conducted using the SIR-2000 attached to a 200 MHz monostatic antenna. The two areas to be surveyed were selected by the archaeologists in situ.Area one was 40 m × 40 m and Area two was 30 m × 15 m. A grid pattern survey in one direction; with one-meter profile s...

Dear researchers, Geoscience and the progress of technology can be put to the service of the environment for the improvement of human living conditions. In this context, the Laboratory of Geodynamics and Natural Resources (LGRN), Department of Geology, The Second Edition of Doctoral Days (2EJD), to be held on January 14 & 15, 2019 at the Faculty of Sciences Dhar El Mahraz, Sidi University Mohamed Ben Abdellah, Fez, Morocco. Research Ph.D. students will then have the opportunity to disseminate their research and share their experiences with other researchers. This edition will cover a wide range of topics in the fields of Geoscience and Natural Resources. Researchers who want to participate in the event Email: [email protected] We look forward to meeting you at the Faculty of Sciences Dhar El Mahraz.

With this depletion in the groundwater table, there has been an overuse of water in the aquifers. Hence, in order to study the subsurface geology of the area and in order to investigate the aquifer presence in the area, we selected 8 points namely S1 to S8 for Vertical Electrical Soundings (VES1 to VES8 respectively). Using this method, resistivity data was collected, interpreted and aquifer strata were explored which is the main aim here. Schlumberger electrode configuration was used here. IGIS DDR3 DC resistivity meter was used to carry out the exploration in Chapabandi mouza, Durgapur, District Burdwan, West Bengal having lateral extension of 600m (AB). Hence the penetration depth of current was nearly 160-170m. It was established that a deeper claysand stratum exists comprising of medium to fine grained sand at points S2, S4and S7 where drilling up to 150-160m was recommended.

This brief review presents the international approaches to
assessment of the content of geotaxis impurities (residual solvents
and various inorganic and organic impurities) in pharmaceuticals.
Nowadays, it has become necessary to provide not only purity
profile but also impurity profile of a particular pharmaceutical
product because of national and international regulations. These
aspects along with significance of the quality, efficacy and safety
of pharmaceuticals, including the source of impurities, kinds
of impurities, control of impurities and regulatory aspects are
discussed.

Recently, encouraging results have been obtained to estimate hydraulic conductivity in unconsolidated sediments from induced polarisation (IP) measurements. The work focussed on laboratory experiments in order to establish semi-empirical relationships between complex electrical conductivity and hydraulic parameters. Although field studies are certainly important to evaluate the feasibility of the method in practice, only a limited number of case histories have

To improve the knowledge of the regionally important Continental Terminal 3 (CT3) aquifer in south-western Niger, fifteen magnetic resonance soundings (MRS) were carried out in December 2005 in the vicinity of wells and boreholes. The output MRS geophysical parameters, i.e. water content and decay constants versus depth, were compared to hydrogeological characteristics, i.e. water table depth, total porosity, specific yield and transmissivity estimated from direct measurements, pumping tests and transient groundwater modelling. The MRS-determined parameters were then used to estimate the rates of groundwater recharge.

Ground-penetration radar (GPR) is a geophysical method that is commonly used in archaeological and forensic investigations, including the determination of the exact location of graves. Whilst the method is rapid and does not involve disturbance of the graves, the interpretation of GPR profiles is nevertheless difficult and often leads to incorrect results. Incorrect identifications could hinder criminal investigations and complicate burials in cemeteries that have no information on the location of previously existing graves. In order to increase the number of unmarked graves that are identified, the GPR results need to be verified by comparing them with the soil and vegetation properties of the sites examined. We used a modern cemetery to assess the results obtained with GPR which we then compared with previously obtained tachymetric data and with an excavation of the graves where doubt existed. Certain soil conditions tended to make the application of GPR difficult on occasions, but a rough estimation of the location of the graves was always possible. The two different methods, GPR survey and tachymetry, both proved suitable for correctly determining the exact location of the majority of graves. The present study thus shows that GPR is a reliable method for determining the exact location of unmarked graves in modern cemeteries. However, the method did not allow statements to be made on the stage of decay of the bodies. Such information would assist in deciding what should be done with graves where ineffective degradation creates a problem for reusing graves following the standard resting time of 25 years.

The MT interpretation procedure begins with a set of sounding data in the frequency domain. The overall quality of these data can be variable both as a function of frequency and location. Many simple interpretation procedures, such as the assessment of static distortion, act directly on the sounding data. A number of response characteristics, such as the location (in frequency) and number of turning points, are important to the interpretation. Localised scatter (noise) in the response estimates can produce false gradients which degrade the quality of the inferences made from the data. This study considers how the D + solution can be used to process the raw sounding data to provide a number of interpretational advantages. Although the D + solution has strict formal roots in 1D inverse theory, it is used here simply to enhance those data attributes, particularly that of physical validity, which lead to a more meaningful assessment of data characteristics. The data considered are 84 broadband array soundings from the Paraná basin, Brazil. The advantages provided by the D + processed data set are demonstrated by using the raw and processed data in two main interpretational procedures. The first procedure concerns the ability of the data to provide quantitative assessments of the influence of static distortion. The second procedure concerns the application of transform methods which attempt to recover a resistivity/depth or reflectivity profile directly from the sounding data.

Stratigraphy and the oil industry are intricately intertwined and have been so ever since the early days of hydrocarbon exploitation. Stratigraphic understanding forms the basis for all upstream activity from basin exploration through field evaluation to reservoir development and production. In the quest for hydrocarbons, both the exploration and exploitation programs can be greatly enhanced by applying stratigraphic analysis. This technique provides the explorationist with the capability to recognize, discover and evaluate new hydrocarbon reservoirs and to reduce the risk in management's decision-making.
Stratigraphic approach to hydrocarbon studies can make use of high-resolution biostratigraphic and pale bathymetric data, well-log signatures and seismic-reflection profiles, and well core data to determine the lithostratigraphy, lithofacies, depositional sequences, and the sequence boundaries.
This study explores the integration of seismic and well-log data for stratigraphic studies. The identification of depositional environments from well logs is based on the principle that well log responses are related to changes in thickness, texture, grain size, and lithology along the well path, while the relection pattern recorded on seismic sections can be interpreted in term of depositional environment and lithofacies.
A case study of the Sequence Stratigraphy of Akos Field in the Coastal Swamp Depobelt of the Niger Delta was considered. From which it can be concluded that the integration of seismic and well log data for stratigraphic studies is a valuable tool for oil and gas exploration.

Collapse and overtopping repeatedly occur in LUSI Embankment. Discontinuities (crack or fracture) in the embankment are major reasons for embankment failures or collapses. Very-low frequency electromagnetic (VLF-EM) measurement is essentially a non-destructive technique which displays subsurface 2-D cross section of resistivity. The cross section result has the possibility of detecting discontinuities and liquid saturation in embankment before it collapsed by observing which part of it in the cross section has low resistivity. This paper presents results of a survey conducted at the LUSI embankment in Eastern Java, Indonesia in a part of potential collapse. VLF-EM profiles measured along the embankment crest provided an overview of the whole embankment and served to detect anomalous zones. The noise assisted multivariate empirical mode decomposition (NA-MEMD) is applied to reject unwanted VLF-EM noise and Inv2DVLF software is applied to obtain result of 2-D resistivity models. In the selected area, the drill log and the standard penetration test (SPT) value gave detailed information about subsurface layer below embankment. This information is valuable for supporting 2-D resistivity image obtained from VLF-EM data inversion. Furthermore, the low resistivity in embankment layer is associated to discontinuities (fracture, crack or fault) along the embankment which caused its collapse.

Different types of sinkholes have been recognized in the Kingdom of Saudi Arabia. The sinkholes are of various sizes and shapes and occur at different depths. Their presence may create a direct risk to the infrastructural facilities such as urban areas, roads, future development areas, and farmlands. Recently, more than eight sinkholes have collapsed to the west of the Al Khafji and An Nu'ayriyah areas (northern eastern side of the Kingdom). Geologically, the area is composed of Dammam, Hadrukh, and Dibdibba formations. The essence of this paper is to integrate remote sensing analysis throughout surface features with the geophysical studies to detect the subsurface sinkholes. Our findings show that there are possible correlations between the clear circular features (ring structures) detectable in remote sensing images and geophysical observations (using two electrical resistivity surveys), indicating unconsolidated material in the subsurface (karst phenomena).

An important problem of marble-quarry management is assessing the quality and the homogeneity of quarry blocks before excavation. In this study, we decided to image the limestone, which we studied in a marble quarry, in terms of layer thickness, discontinuities and cavities using the ground-penetrating-radar (GPR) method. The method was successfully applied to detect and map the fractures with the cavities in a marble layer according to depth in the Ankara City Polatli Town (Turkey) region, which represents upper Miocene-Pliocene lacustrine carbonate rocks.

The aim of this study is to define and characterize water bearing geological formation and to test the possibility of using geophysical techniques to determine the hydrogeological parameters in three areas in the Vientiane basin, Laos. The investigated areas are part of the Khorat Plateau where halite is naturally occurring at depths as shallow as 50 m in the Thangon Formation. Magnetic Resonance Sounding (MRS) has been used in combination with Vertical Electrical Sounding (VES) in different geological environments. In total, 46 sites have been investigated and the MRS and VES recognized the stratigraphic unit N 2 Q 1-3 , consisting of alluvial unconsolidated sediments, as the main water bearing unit. The aquifer thickness varies usually between 10 and 40 m and the depth to the main aquifer range from 5 to 15 m. The free water content is here up to 30%, and the decay times vary between 100 and 400 ms, suggesting a mean pore size equivalent to fine sand to gravel. The resistivity is highly variable, but usually around 10-1500 Ω-m, except for some sites in areas 1 and 2, where the aquifer is of low resistivity, probably related to salt water. Hydraulic and storage-related parameters such as transmissivity, hydraulic column, have been estimated from the MRS. The MRS together with VES has been shown to be a useful and important tool for identifying and distinguishing freshwater from possible salt-affected water as well as the salt-related clay layer of the Thangon Formation. This clay layer is characterized by very low free water content and a resistivity lower than 5 Ω-m and can be found in all 3 areas at depths from 15 to 50 m.

The paper presents a numerical algorithm that performs accurate lithology corrections for thermal (CNL/TNPH, CNL/NPHI) and epithermal (SNP) neutron logs, in the whole range of porosities normally encountered in practice. It is known that neutron logs respond not only to a formation’s true porosity, but, to some extent, also to its lithology (the so-called "matrix effect"). Because the matrix effect is nonlinear and varies with true porosity, which is unknown beforehand, an iterative process is needed in order to carry out proper lithology corrections and obtain formation's porosity. The relationships between measured neutron porosity and true porosity for the common reservoir lithologies (sandstones, limestones and dolomites), at different formation water salinities, are approximable via suitable regression polynomials. Nonlinear neutron responses thus expressed are combined with the responses of density and sonic velocity logs, together with the volumetric unity constraint, into a system which is solved using a Newton-Raphson root-finding routine. The algorithm, implemented as a set of Matlab™ codes, provides optimal petrophysical models for the interpretation of neutron-density-sonic log suites and is easily adaptable in order to include additional linear or nonlinear log response equations. A case study regarding its applicability is also presented in the paper.

Laboratory and field measurements were made in a study of a small number of chromite deposits in the Josephine ultramafic complex of northwest California, to examine their physical properties and to search for possible diagnostic geophysical signatures. Though the sample was small, the results show that no single geophysical method gives  unequivocal identification of buried massive pods of chromite, but that a combination of gravity, magnetics, and seismics, and complex resistivity might be used to explore successfully if used in a systematic fashion. Some of the geophysical signatures appear to be secondary or associative in nature, raising the possibility that a specific method or combination of methods might have to be modified for application in
an area other than where they were developed.

In hydrogeology there is a variety of empirical formulae available for determination of hydraulic conductivity of porous media, all based on the analysis of grain size distributions of aquifer materials. Sensitivity of NMR measurements to pore sizes makes it a good indicator of hydraulic conductivity. Analogous to laboratory NMR, Magnetic Resonance Sounding (MRS) relaxation data are of a multi-exponential (ME) nature due to the distribution of different pore sizes in an investigated rock layer. ME relaxation behaviour will also arise due to the superposition of NMR signals which originate from different layers. It has been shown, that both kinds of ME behaviour coexist in MRS and can principally be separated by ME inversion of the field data. Only a few publications exist that have proposed approaches to qualitatively and quantitatively estimate petrophysical parameters such as the hydraulic conductivity from MRS measurements, i.e. MRS porosity and decay times. The so far used relations for the estimation of hydraulic conductivity in hydrogeology and NMR experiments are compared and discussed with respect to their applicability in MRS. Taking into account results from a variety of laboratory NMR and MRS experiments mean rock specific calibration factors are introduced for a data-base-calibrated estimation of hydraulic conductivity when no on-site calibration of MRS is available. Field data have been analysed using conventional and ME inversion using such mean calibration values. The results for conventional and ME inversion agree with estimates obtained from well core analysis for shallow depths but are significantly improved using a ME inversion approach for greater depths.

In contrast to the use of marine seismic reflection techniques for reservoir-scale applications, where seismic inversion for quantitative sediment analysis is common, shallow-water, very-high-resolution seismic reflection data are seldom used for more than qualitative reflection interpretation. Here, a quantitative analysis of very-high-resolution marine seismic reflection profiles from a shallow- water (<50 m water depth) fjord in northern Norway is presented. Acquired using Sparker, Boomer, and Chirp sources, the failure plane of multiple local landslides correlates with a composite reflection that reverses polarity to the south. Using a genetic algorithm, a 1D post-stack acoustic impedance inversion of all three profiles is performed, calibrating against multi-sensor core logger (MSCL) data from cores. Using empirical relationships the resulting impedance profiles are related to remote sediment properties, including: P-wave velocity; density; mean grain size; and porosity. The composite reflector is consistently identified by all three data sources as a finer-grained (by one Phi), lower density (c. 0.2 g/cm3 less than background) thin bed, with an anomalous low velocity zone (at least 100 m/s lower than background) associated with the polarity reversal to the south. Such a velocity contrast is consistent with an accumulation of shallow free gas trapped within the finer- grain, less permeable layer. This study represents the first application of acoustic impedance inversion to very-high-resolution seismic reflection data and demonstrates the potential for directly relating seismic reflection data with sediment properties using a variety of commonly used shallow seismic profiling sources.

Geophysical methods play an important role in exploration strategies worldwide. The addition of such data can contribute to a better understanding of the geological sector of interest. By carefully applying basic principles, explorers can maximize their chances for success: 1) Seek a rigorous understanding of the physical properties of the rocks under investigation 2) Associate geophysical data with geological data and expertise to better constrain the geological model 3) Use creativity to interpret new data and/or re-interpret historical data in order to provide new insights about the geological processes being studied.

2D seismic refraction data, from seven traverse lines, were used to investigate subsurface geology in the Appollonian Formation of the onshore Tano Basin of Ghana. Tano Basin is one of the four basins of Ghana and the most important one when it comes to oil potential of Ghana. The survey covered approximately a total area of about 113,000 m 2. With the exception of one traverse line which had the length of 60 m, each of the remaining traverse lines had a length of 120m. The results from the data analysis indicated that, the surveyed area is underlain by three geological units although results from two traverse lines revealed two geological units. The P-wave velocity of the first layer ranges between 335.00-468.00 m/s and the average velocity of 391.57 m/s. It has a thickness range of 5.0-27.5 m with an average thickness of 16.25 m. The layer is interpreted as a weathered layer and consist of soil and dry loose sand which might be formed as beach deposit. The second layer has P-wave velocity range of 590.00-1133.00 m/s and the average velocity of 881.71 m/s. The layer thickness ranges between 14.5-31.0 m and the average of 25.80 m. The layer may consist of unconsolidated water-saturated sand and clay. The last layer detected by this survey has P-wave velocity range of 1068.00-2724.00 m/s and the average of 2074.20 m/s. The layer is interpreted as the bedrock underlining the surveyed area. The layer may consist of gravel, sandstone and limestone.

The determination of index properties of rock, such as Cerchar Abrasivity Index, Shore Hardness, Protodyakonov Index and Vickers Hardness in laboratory or insitu conditions is time-consuming and requires special equipment and expertise. However, the use of P-wave technology to measure the P-wave velocity of rock is a relatively simple task because the portable equipment can be used in the laboratory or in the field without tedious preparation of rock cores and it is non-destructive. This paper presents an experimental study of the measurement of P-waves of several types of igneous, sedimentary and metamorphic rock. The index properties were also determined in the laboratory to obtain correlations between P-waves and various index properties. Good linear relationships were found between all the index properties determined and the P-wave measurements.

Electrical Resistivity Tomography (ERT) has been used in association with Standard Penetration Test (SPT) and Dynamic Cone Penetration Test (DCPT) for Geotechnical investigations at two sites, proposed for thermal power plants, in Uttar Pradesh (UP), India. SPT and DCPT tests were conducted at 28 points and two ERT profiles, each measuring 355 m long, were recorded using 72 electrodes deployed at 5 m spacing. Electrical characterization of subsurface soil was done using borehole data and grain size analysis of the soil samples collected from boreholes. The concept of electrical resistivity variation with soil strength related to the grain size distribution, cementation, porosity and saturation has been used to correlate the transverse resistance of soil with the number of blow counts (N-values) obtained from SPT and DCPT data. It was thus observed that the transverse resistance of soil column is linearly related with the number of blow counts (N-values) at these sites. The linear relationships are site-specific and the coefficients of linear relation are sensitive to the lithology of subsurface formation, which was verified by borehole data. The study demonstrates the usefulness of the ERT method in geotechnical investigations, which is economic, efficient and less time consuming in comparison to the other geotechnical methods, such as SPT and DCPT, used for the purpose.

An innovative sensor technique has been developed to detect water leaks in supply pipes, especially in cases where the existing prevailing methods do not offer reliable solution, such as in PVC pipelines or for minor leaks. The presented system uses a Continuous Wave (CW) Doppler sensing unit operating at 2.45 GHz, consisting of a low power transmitter, a homodyne receiver and a digital signal processing unit. The operation principle is the detection of the Doppler frequency shift of the reflected electromagnetic wave by slightly moving water that leaks out of a pipe. A first prototype has already been developed and tested in test sites as well as in real water leaking conditions. The system has additionally been compared to the commercially available water leaking methods, verifying its reliability and accuracy in the detection of water leaks.

Since 2016 the Department of Culture and Civilization History at the University of Bologna has been conducting a study under the direction of Giuseppe Lepore and Enrico Giorgi, on the 3rd insula of the Roman Hellenistic Quarter of Agrigento. The tradition of studies starts from the latter part of 1800, but many questions remain. One of these concerns the original phases of the urban planning ascribed to the pre-roman age (VI-V century BC) of which there are currently few traces. We have tried to give attention to the preventive archaeology through a methodological and innovative approach with surveying techniques and non-invasive investigation of the subsoil (coordinated by Federica Boschi). The investigation carried out with the GPR method – where possible – involved all the houses of the insula III and the stenopòs III for a total surface area of around 5600 square meters. With the geomagnetic method in gradiometric configuration was carried out an investigation in an open country spaces never explored before again. Both methods proved to be quite effective, although some limitations were found during the acquisition phase due to disturbances caused by logistic impediments (tight spaces inside the already excavated houses; metal bounding fences and trees in pasture spaces) and the
physical characteristics of the site. These factors have partially affected the interpretation of the data, making it more problematic. Despite the difficulties the results obtained have given us important data that will contribute to the wider debate on the evolution of the housing area.

Small, low cost Autonomous underwater vehicles (AUVs) provide ideal platforms for shallow water survey, as they are capable of unmanned navigation and can be programmed to acquire data at constant depth, or constant altitude above the seabed. AUVs can be deployed under most sea states and are unaffected by vessel motions that often degrade sonar and magnetometer data quality. The integration of sonar and magnetometer sensors on AUV’s is challenging, however, due to limited payload and strong magnetic fields produced by the vehicle motor.
In this study, a Marine Magnetics Explorer Overhauser magnetometer was mated to a portable AUV (OceanServer Iver2) creating the first practical AUV- deployed magnetic survey system. To eliminate magnetic interference from the AUV, the magnetometer was tethered to the AUV with a 5 m tow cable, as determined by static and dynamic instrument testing. The results of the magnetic tests are presented, along with field data from a shallow water test area in Lake Ontario near Toronto, Canada. AUV-acquired magnetic survey data were compared directly with a conventional boat-towed magnetic survey of the same area. The AUV magnetic data were of superior quality despite being collected in rough weather conditions that would have made conventional survey impossible. The resulting high-resolution total magnetic intensity and analytic signal maps clearly identify several buried and surface ferrometallic targets that were verified in 500-kHz side- scan sonar imaging and visual inspection by divers.

The electromagnetic profiling and Vertical Electrical Sounding (VES) data were acquired from some communities in the Twifo-Hemang Lower Denkyira District of the Central region of Ghana, in order to determine zones of high groundwater potentials and to recommend suitable sites to drill boreholes for community water supply. The research reported here covered three communities namely; Esukese Ekyire, Kwanyarko. First the electromagnetic measurements were carried out, qualitative interpretations of the data were carried out and weathered rock zones were identified. Then the VES measurements using Schlumberger array were conducted at points on the electromagnetic traverse that displayed weathered zones. ZONDIP1D software was used in creating 1D sounding curve models of geological subsurface structures beneath the sounding points. Results of the modelling suggest that the communities are underlain by three to four geological layers. Interpretations of the 1D inversion of the VES data provide the resistivities and thicknesses of subsurface layers. On the basis of resistivity values and thicknesses of the layers in the 1D models, sites were recommended to drill boreholes for community water supply.

Integrated electrical and electromagnetic surveys were carried out in hard rock areas of Purulia district (West Bengal), India, for delineation of groundwater-bearing zones that would be suitable for construction of deep tube-wells for large amounts of water. Groundwater movement that occurs through fractures in hard rocks is suitable to be delineated by very low frequency (VLF) electromagnetic surveys. A detailed survey of the area was done using a VLF-WADI instrument and appropriate locations were selected for further study using Schlumberger resistivity sounding. Hence, the entire area was surveyed in a relatively short time by the combined use of resistivity and electromagnetic surveys.

Introducing and applying an appropriate strategy for reservoir modeling in strongly heterogeneous and fractured reservoirs is a controversial issue in reservoir engineering. Various integration approaches have been introduced to combine different sources of information and model building techniques to handle heterogeneity in geological complex reservoir. However, most of these integration approaches in several studies fail on modeling strongly fractured limestone reservoir rocks of the Zagros belt in southwest Iran. In this study, we introduced a new strategy for appropriate modeling of a production formation fractured rock. Firstly, different rock types in the study area were identified based on well log data. Then, the Sarvak Formation was divided into nine zones, and the thinner subzones were used for further fine modeling procedure. These subzones were separated based on different fracture types and fracture distribution in each zone. This strategy provided sophisticated distribution of petrophysical parameters throughout the grids of the model, and therefore, it can handle strong heterogeneity of the complex reservoir. Afterward, petrophysical parameters were used to produce an up-scaled 3D gridded petrophysical model. Subsequently, maps of petrophysical properties were derived for each zone of the Sarvak Formation. Evidences achieved in this study indicates Sarvak Formation zone 2 as the target production zone with better performance of reservoir rock and the southwestern part of the field as area of maximum porosity.