Geophysical Survey Methods Research Articles

Laboratory Assessment of Chemical Characteristics using Electrical Resistivity (ER) Technique in Highway Construction

Electrical Resistivity (ER) technique was applied for simulation model constructed at University of Technology / Civil Engineering Department Laboratories, Baghdad-Iraq. The study aims to determine the relationship between changing the chemical properties of the soil and the resistivity of soil layers using 1-D VES. ER has been chosen as a nondestructive geophysical survey method to identify some soil characteristics without destructing the soil by making surface measurements using Wenner configuration. The obtained data results showed that there is a relationship between ER and some soil characteristics. The ER values change with the change of soil properties. Two models were created. In the first model, the ER was measured without changing any of the soil characteristics, and it was with optimum water content. In the second model, 5% of the sodium chloride salt was added to the soil after dissolving with water then the ER was measured. It was found that after adding the salt, the ER is decreased significantly, and thus the ER was affected by the addition of the salt.

Integration of geophysics and remote sensing techniques in mapping zones mineralised with disseminated gold and sulphide minerals in Lolgorien, Narok County, Kenya

Even though ground geophysical surveys (especially Induced polarization and resistivity) are applied in mineral exploration, their effectiveness in identification of mineralised zones is often enhanced by integrating other mineral exploration techniques such as remote sensing and geological investigations. Integrating different techniques helps in reducing uncertainty that is often associated with mineral exploration. The methods being integrated also depend on characteristics of mineralisation and those of host rock. In this study, geophysical survey methods (induced polarization and resistivity) were integrated with remote sensing and geological methods to delineate mineralised zones in Lolgorien beyond reasonable doubt. By integrating these methods, it was found that Lolgorien’s gold and sulphide minerals (disseminated minerals) are hosted in massive quartz veins and auriferous quartz veins hosted in Banded Iron Formations. It was also found that this mineralisation was controlled by faults which mainly trend in two directions (NW-SE) and (NE-SW).
 Keywords: hydrothermal alteration, chargeability, resistivity, band ratio, lineament density

GPR imaging of traffic compaction effects on soil structures

Spatial and depth variability of soil characteristics greatly influence its optimum utilization and management. Concealing nature of soil subsurface horizons has made the traditional soil investigations which rely on point information less reliable. In this study, an alternative use of ground penetrating radar (GPR)—a near-surface geophysical survey method—was tested to address the shortcomings. The focus of the study was on assessment of characteristics variability of soil layers at a test site and evaluation of effects of compaction caused by machinery traffics on soil. GPR methods utilize electromagnetic energy in the frequency range of 10 MHz and 3.0 GHz. Fourteen profiles GPR data were acquired at the test site-a farmland in Krakow, Poland. Compaction on parts of the soil was induced using tractor movements (simulating traffic effects) at different passes. Data were processed using basic filtering algorithms and attributes computations executed in Reflexw software. Attempt made in the study was on use of GPR geophysical technique for soil assessment. The method allows delineation of the soil horizons which depicts characteristic depth changes and spatial variability within the horizons. Moreover, traffic effects that caused compaction on parts of the soil horizons were discernable from the GPR profile sections. Thus, similar densification like hardpan that may develop in natural setting can be investigated using the method. The results have shown the suitability of the method for quick, noninvasive and continuous soil investigation that may also allow assessment of temporal soil changes via repeated measurement.

Исследование собственных колебаний нефти в вертикальной скважине

In the oil industry, an important aspect in the production of hydrocarbons is the control of the state of the well and the study of the near-wellbore zone adjacent to it. For this purpose, various geophysical well survey methods (GIS) are used. One of the methods of well logging is acoustic spectroscopy of wells, where the characteristics of the well and reservoir can be studied by means of excitation of natural oscillations of the fluid. In this paper, the problem of natural oscillations of a fluid in a vertical well, which arose as a result of a sharp opening or closing of the well, is investigated. To describe this process, a mathematical model of natural oscillations of the liquid column in the well, which communicates with the reservoir through the permeable walls of the open area, is constructed using the mass and momentum conservation equation in the well area, the mass conservation equation in the open area of ??the well, and the filtration equation in the reservoir. Taking into account the initial and boundary conditions, an analytical solution was found in the form of standing waves to determine the pressure and velocity of oil in the well. The dependences of the oscillation frequency, decrement and damping factor on the reservoir permeability are shown, the pressure dynamics in the well is given and the amplitude of the oscillations is considered. A comparative analysis of changes in such indicators as oscillation frequency, decrement and damping coefficient has been carried out. The influence of such parameters as the length of the bottomhole zone and the permeability coefficient on the nature of the change in the natural fluctuations of the fluid has been established.

PALEOGEOMORPHOLOGICAL FEATURES OF THE SRIBNENSKA DEPRESSION IN THE LOW CARBON TIME ASSOCIATED WITH OIL AND GAS

The work is devoted to the study of geomorphological features of the marine paleobasin and adjacent territories in the Lower Carboniferous time. The object of the study was the Upper Cretaceous terrigenous-domanitic-clay complex deposits of the Dnieper­Donets avalanche. This complex is located within the Sribnenska Depression and its bordering areas. The geological study of this area, borehole data and the results of geophysical survey methods contributed to the possibility of paleogeomorphological modeling of the sedimentary basin. This made it possible to determine the basic criteria and regularities of hydrocarbon trap genesis. Based on the results of well core studies, lithological features of silty-sandy sediments and clayey rocks were established. The Upper Terrigenous-Domanicoid Clayey Complex is predominantly represented by dark-colored flichoidal clayey sediments of the depressive type. Sandstones comprising the terrigenous portion of the complex are characterized by a massive texture and multidirectional layering. Cement in the sandstones is represented by flake monoclinic kaolinite; admixture of degraded hydromica, less frequently calcite, ankerite, and siderite is also observed. Sediments of this type are typical of fluvial outcrops in a depressive, stagnant marine basin. sediments were deposited by submarine delta and turbid currents and contour currents. Paleogeological models reflecting the facies distribution patterns of the paleobasin during the Upper Thaw time have been created on the basis of the logging data. It is shown that structural relations in summer play the role of traps for hydrocarbons. The sedimentation and paleogeomorphological preconditions of oil and gas deposits formation in the terrigenous-domanicoid-clay complex are analyzed on the examples of the known fields and the areas favorable for formation of hydrocarbon deposits are singled out.

Combined Magnetic, Transient Electromagnetic, and Magnetotelluric Methods to Detect a BIF-Type Concealed Iron Ore Body: A Case Study in Gongchangling Iron Ore Concentration Area, Southern Liaoning Province, China

The detection and evaluation of concealed mineral resources deep in metallic mines and in the surrounding areas remain technically difficult. In particular, due to the complex topographic and geomorphic conditions on the surface, the detection environments in these areas limit the choices of detection equipment and data collection devices. In this study, based on metallogenic theory and the metallogenic geological characteristics of banded iron formation (BIF)-type iron ores, equipment for surface geophysical surveys (i.e., the high-precision ground magnetic survey method, the transient electromagnetic method, and the magnetotelluric method) and data collection devices capable of taking single-point continuous measurements were employed to detect the concealed iron ore bodies in the transition zone CID-1 between the Hejia and Dumu iron deposits in the Gongchangling iron ore concentration area in the Anshan-Benxi area (Liaoyang, China), a representative area of BIF-type iron ores. The results showed that an optimal combination of these geophysical survey methods accurately determined the anomalous planar spatial locations and anomalous profile morphologies of the concealed iron ore bodies. On this basis, we determined their locations, burial depths, and scales. Two anomalous zones induced by concealed iron ore bodies, YC-1 and YC-2, were discovered in zone CID-1. Two concealed iron-bearing zones, one shallow (0–150 m) and one deep (300–450 m), were found in YC-1. A 100 m scale drilling test showed that the cumulative thickness of the shallow iron-bearing zone was over 23.6 m.

Condition Assessment of Building Foundation in Karst Terrain Using both Electrical Resistivity Tomography and Multi-channel Analysis Surface Wave Techniques

In foundation survey projects for hotel buildings in Kentucky, assisted by drilling data, an integrated geophysical survey was undertaken. The main goal of the project was to investigate the depth of the top rock and the void locations, if any present. The project used shallow non-invasive geophysical survey methods, including electrical resistivity tomography (ERT) and multi-channel analysis of surface wave (MASW). A shallow subsurface survey was performed using the MASW equipped with a 24-geophone array, equipped with 4.5 Hz geophones to estimate the clay/soil thickness. The 22 2-d ERT profiles for imaging resistivity changes in subterranean formations were used to survey the top rock and delineate possible karst areas in the area. These methods successfully reflect the top of the rock at an average depth of about 60 ft. Additionally, several relatively large karst feature zones in the study area were mapped with the use of the ERT data. Finally, the 2-d ERT profiles were used to study the geological properties of the foundation structure. Using the established geophysical model, the internal structure of the foundation was revealed. The results are in good agreement with the actual situation in the study area as evinced by available borehole data, and can guide engineers when solving foundation problems and reveal the weakness of the karst lava development area that may appear under a foundation during its construction.

The Use of Combined Geophysical Survey Methods for Groundwater Investigation in a Typical Basement Complex Terrain: Case Study of Erunmu, Ibadan, Southwest Nigeria

A combined Survey involving the very low frequency electromagnetic (VLF – EM) and Electrical resistivity surveys were carried out in order to appraise the groundwater potential, and locate appropriate positions for sighting boreholes in Erunmu Community, Egbeda local government area, Oyo State, Nigeria. VLF data were obtained along five traverses as the first step in order to locate suitable vertical electrical sounding (VES) stations. Vertical Electrical Soundings using Schlumberger array were thereafter carried out at twenty 20) locations. The integrated interpretation of both data confirms the presence of aquifers, which includes, weathered zone and basement transition/fractures beneath the area, which prior to this investigation have a history of failed boreholes and wells. The resistivity curve types obtained includes H and A which revealed the presence of 3 to 4 subsurface layers consisting of topsoil, the clay, the sandy clay, fractured zone and the highly resistive bedrock. The resulting geo-electric section from the interpretation revealed the Reflection coefficient which ranges from 0.45 – 0.98. The dominated curve type in the area investigated is the H which is typical of basement complex while the A-type is about 20% of the total curves. Hydrogeological, the topsoil is not important because the degree of water saturation in this layer is very low and cannot be utilized for groundwater. The fractured basement layer (which is present in less than 15% of the study area is very relevant in groundwater prospecting; when it is thick enough the layer could support borehole drilling. Areas identified as geological interfaces in the VLF anomaly charts were also confirmed by the interpreted VES data as poor and intermediate zones for groundwater potential in the study area. The significance of this study is such that it will serve as a useful reference for future research efforts in the aspect of basement complex groundwater studies.

Polarity Change Extraction of GPR Data for Under-road Cavity Detection: Application on Sudeoksa Testbed Data

Ground penetrating radar (GPR) is one of the most widely used geophysical survey methods to locate cavities under roads due to its speedy exploration and high-resolution imaging. To locate underground cavities using GPR, we need to distinguish between cavity-induced reflections and other reflections, which can be achieved by examining the polarity change in reflections compared to the polarity of the transmitted signal. The polarity change can be measured from the phase shift between the target and first reflections. To estimate the phase shift in reflections, the method of computing the power spectrum difference between the original trace and background signal was proposed, but the method has a limitation for shallow reflectors. As an alternative method to avoid this limitation, we propose using only one component of the power spectrum difference, the cross-correlation between the target reflection and background signal. The cross-correlation has its maximum peak at a time lag between the target and first reflection (from the air-ground interface). Additionally, the phase at that time lag represents a phase shift between the two reflections. We compare our cross-correlation-based method with the conventional method of computing the whole power spectrum difference and investigate the feasibility of our method for distinguishing cavity-induced reflections using a 2D field data set acquired in a testbed in Sudeoksa, Korea.

The Messapic Site of Muro Leccese: New Results from Integrated Geophysical and Archaeological Surveys

The regular application of geophysical survey techniques to evaluate archaeological sites is well established as a method for locating, defining, and mapping buried archaeological materials. However, it is not always feasible to apply a range of different methods over a particular site or landscape due to constraints in time or funding. This paper addresses the integrated application of three geophysical survey methods over an important archaeological site located in south Italy. In particular, it is focused on the results achieved from a past geophysical survey and the ongoing excavations performed by archaeologists in the site of Muro Leccese. Muro Leccese (Lecce) is one of the most important Messapian archaeological sites in southern Italy. The archaeological interest of the site was generated since the discovery of the remains of Messapian walls (late 4th–3rd centuries BC). With the aim of widening the archaeological knowledge of the Messapian settlement, several integrated methods, including magnetometry, ground-penetrating radar, and electrical resistivity tomography were used on site to fulfill a number of different research objectives. Since the most important targets were expected to be located at shallow soil depth, a three-dimensional (3D) ground-penetrating radar (GPR) survey was carried out in two zones, which were labeled respectively as zone 1 and zone 2, and were both quite close to the archaeological excavations. The GPR investigations were integrated with a 3D electrical resistivity tomography (ERT) survey in zone 1 and with a magnetometric, in gradiometry configuration survey in zone 2. The integration of several techniques allowed mapping the structural remains of this area and leading the excavation project. The geophysical results show a good correspondence with the archaeological features that were found after the excavation. Current work on the geophysical survey data using different codes for the processing of the data and merging different datasets using a Geographic Information System allowed achieving a user-friendly visualization that was presented to the archaeologists.

Development of the exploration method and integrated interpretation tool for Seafloor Massive Sulfide（SMS）

In recent years, numerous geophysical survey method has been developed for exploring the marine resources in the EEZ （Exclusive Economic Zone） of Japan. Exploration targets have been gas hydrates, mineral resources （manganese nodule, cobalt rich crust or rare earth） and especially seafloor massive sulfide （SMS） deposits.

Data-Driven Attenuation Compensation Via a Shaping Regularization Scheme

Seismic prospecting is one of the most important geophysical survey methods to understand the earth's structure. Properly compensating the anelastic attenuation of seismic data help to clearly characterize the structure of subsurface. Inverse Q-filtering processing is one of the most efficient ways to compensate for anelastic attenuation caused by the earth's structure. Stability is the most challenging task in inverse Q-filtering processing. In this letter, we introduce a shaping regularization method to stabilize the amplitude compensation operator in the inverse Q-filtering. The stabilization operator can be used simultaneously with a phase correction operator. To further improve the robustness of our method to noise, we adopt an adaptive tapering window to control the compensation frequency components according to the frequency bandwidth of seismic data. These schemes can accentuate the attenuated amplitude through Q-filtering and improve the stability of our method to noise. To demonstrate the effectiveness of our method, we first apply it to synthetic examples and to a real seismic data. Both results illustrate that the proposed shaping regularization inverse Q-filtering is an efficient adaptive data-driven inverse Q-filtering method.

Identification of Karstic Features in Lateritic Soil by an Integrated Geophysical Approach

Lateritic soils are widely spread across the southern and central parts of India. Lateritic formations usually have soft sediments, entrapped between hard to medium soft lateritic rock, which are leached due to the ingress of water during rainy seasons creating hollow sections or cavities which span over large lengths. Laterites are highly heterogeneous and prone to cavitation due to its weathering process; a sound knowledge of the subsurface condition is required before starting any construction. This study presents the application of integrated geophysical investigation for the identification of cavities at a mega construction site in Kerala State, India. Geophysical survey methods, namely ground penetrating radar (GPR) and multichannel analysis of surface waves (MASWs) techniques, are used to identify the heterogeneities in lateritic soils and localized cavities. The survey areas identified are critical sections of a mega construction project subjected to heavy dynamic and static loads. The preliminary GPR survey is carried out across the study areas at specific interval spacing to identify probable heterogeneities. Confirmative survey or detailed GPR and MASW surveys are carried out at the locations identified in the preliminary survey at close intervals to confirm the presence of an anomaly and identify its location. The anomalies in the GPR radargram are identified by visual inspection and trace amplitude approach. Using MASW survey, a 2D shear wave velocity profile is generated to identify low shear wave velocity zones which confirm the presence of an anomaly. On comparing the data from both GPR and MASW survey techniques, the underground cavities were successfully identified at multiple locations with further crosschecking with borings. The study further provided details on subsurface lithology at survey locations.

First evidence of a lake at Ancient Phaistos (Messara Plain, South-Central Crete, Greece): Reconstructing paleoenvironments and differentiating the roles of human land-use and paleoclimate from Minoan to Roman times

Phaistos was one of the most important Minoan palaces in Crete and previous studies have addressed its relationship with the paleo-seashore position during historical times. Here, we reconstruct the environmental evolution of Phaistos from Early Minoan to Roman times. Study of two stratigraphic sections and nine boreholes drilled in the westernmost part of the Messara Plain has revealed the stratigraphy of the Mid- to Late-Holocene sediments. Laboratory analyses comprise granulometry, magnetic susceptibility measurements and identification of mollusks, diatoms and pollen grains. Eighteen radiocarbon dates provide a robust chronostratigraphy. In addition, a geophysical survey (electric resistivity tomography (ERT) method) was conducted to reveal the sub-surface morphology in the coring area. The results reveal that a freshwater lake existed from ca. 2100–2000 BC to ca. 1200–1100 BC, which subsequently became swampland until ca. 700 BC. A lake retreat is identified at ca. 1200–1000 BC and can be interpreted as resulting from the 3.2 cal kyr BP rapid climate change (RCC) dry event, observed elsewhere in the Eastern Mediterranean. Subsequently, from the 7th to the 5th century BC, there was the input of detrital material and fluvial dynamics prevailed until at least Roman times. The origin of the lake and its disappearance are discussed in the context of regional climate change and local tectonic activity, without excluding possible human influences. We also reconstruct the vegetation history for the period from the Late Minoan to the Early Archaic period. Pollen analysis reveals a Mediterranean maquis landscape dominated by Olea, together with hygrophilous vegetation, and highlights a clear transition from limnic to swampy environmental conditions around 1100 BC. The pollen sequence is also important for assessing the impact of the 3.2 cal. kyr BP RCC event and for assessing the possibility of an abrupt discontinuity in human activity around Phaistos after the demise of the Minoan Civilization.

Creating volume estimates for buried shell deposits: A comparative experimental case study using ground‐penetrating radar (GPR) and electrical resistivity under varying soil conditions

AbstractSampling issues represent a persistent problem in shell matrix research, particularly for large shell deposits. When small samples are taken from large buried deposits it is almost impossible, under current research practices, to understand how representative that sample is of the overall deposit. This case study tests a novel method for creating a better understanding of the buried deposits from which excavated samples are taken, thereby allowing for improved sampling strategies and a better understanding of how representative those samples are of the overall site. The case study employs two geophysical survey methods, ground‐penetrating radar (GPR) and electrical resistivity, to investigate buried shell deposits under experimental conditions. The survey results were used to create volume estimations and three‐dimensional (3D) models of buried shell deposits. This method is novel to shell matrix research and the current case study was designed to test the viability of the method under differing conditions. As well as testing the two geophysical methods, surveys were conducted under different moisture levels, soil types and survey transect spacings. Results showed that the 3D models and volume estimates of the deposit were successful in creating a representative understanding of the nature of the buried deposit, but with varying degrees of accuracy. GPR results created more accurate volume estimates and 3D models than the electrical resistivity results. Both geophysical methods produced more accurate results under drier conditions, though the electrical resistivity produced more visually distinct results with higher moisture levels. Analysis of the volume results revealed an error margin (to a confidence level of 95%) of 9.5% ± 15.5% for the GPR, and 44.5% ± 31.5% to 56 ± 70.5% for the electrical resistivity, depending on the interpretation method used to create the models.

Feature-Scale Analysis Using Ground-Penetrating Radar and Low Altitude Prospection at the Collins Mounds Site, Northwest Arkansas

Geophysical survey and other non-invasive methods are, in some cases, the only options available for archaeological investigation. This is exemplified at the Collins site, a possible Late Woodland to Middle Mississippian period, multi-mound, civic ceremonial center in Northwest Arkansas. The site is located on private property and although excavation is not allowed, non-invasive survey methods are permitted on its northern section. This paper presents the results of a ground-penetrating radar survey over Mounds B, C, and D. The results reveal a number of features that are interpreted as mortuary structures as well as evidence of multiple building episodes over time within distinct layers of Mound C. A high-resolution DEM generated with aerial imagery is used in interpreting the GPR data as well as to provide an updated map of mound size and distribution. By integrating the GPR data with the DEM, orthoimagery, and magnetic gradiometry data from a previously documented survey, and comparing the results to ethnohistoric accounts, interpretation of the geophysical data is enhanced. Geophysical survey is often used to assess an archaeological site on a landscape scale. By narrowing the scope to individual mounds, this article demonstrates how multiple, complementary technologies, when used in concert, can inform on the feature level.

Geoarchaeological Core Prospection as a Tool to Validate Archaeological Interpretation Based on Geophysical Data at the Roman Settlement of Auritz/Burguete and Aurizberri/Espinal (Navarre)

Geophysical survey methods are broadly used to delimit and characterize archaeological sites, but the archaeological interpretation of geophysical data remains one of the challenges. Indeed, many scenarios can generate a similar geophysical response, and often interpretations can not be validated without access to the subsoil. In large geophysical surveys many anomalies are detected and validation through archaeological trenches can not be afforded. This paper analyses the validity of geoarchaeological core survey to check the archaeological interpretations based on geophysical results. The Roman site located at Auritz/Burguete and Aurizberri/Espinal (Navarre), provides a great case of study as many investigations have been carried out. After the gradiometer survey performed in 2013 a sediment core survey was designed. 132 cores were drilled using a hand-held coring machine and the sediments were analysed in situ. Site delimitation and archaeological interpretations based on magnetic data could be improved or corrected. In this regard, the core survey proved to be an useful methodology as many anomalies could be checked within reasonable time and resources. However, further geophysical investigations trough GPR revealed unexpected remains in areas where no archaeological deposits were identified through coring. Excavations showed poor conservation level in some of those areas, leading to thin archaeological deposits hard to identify at the cores. The sediment core survey, therefore, was proved to be inconclusive to delimit the archaeological site.

Equivalent-linear site response analysis on the site of the historical Trakošćan Castle, Croatia, using HVSR method

This paper presents a major extension of seismic vulnerability research project on the site of Trakoscan Castle based on the initial horizontal-to-vertical-spectral-ratio (HVSR) results from Stanko et al. (2016). The estimated HVSR site frequencies and HV amplification at Trakoscan Castle can only be used as an indication of the initial soil site frequency and amplification, so-called natural soil model, corresponding to the subsoil profile without the influence of an earthquake. The equivalent-linear (EQL) site response analysis has been carried out for different earthquake scenarios for a maximum input rock peak ground acceleration (PGAROCK) that corresponds to return periods of 95 (0.08 g), 475 (0.18 g) and 1000 years (0.31 g). The aim of the research is to evaluate structural seismic design responses and to determine type and degree of damage caused by local site effect, which is the result of an alluvial basin and topographic influences. The main objective of this research is the formation of local microseismic zones based on an EQL analysis: surface spectral acceleration and amplification maps at the predominant frequency. Based on the HVSR frequency response of the core structure of Trakoscan Castle and the Tower itself (fundamental and higher frequency modes), maps of surface spectral acceleration and soil amplification at different frequencies (3, 5 and 10 Hz) are developed for different input PGAROCK levels (0.08, 0.18 and 0.31 g) to evaluate seismic response of the Castle. Observed amplifications are correlated with ground motion polarization and directionality of the ground motion from the alluvial basin to the hilltop. Shortening of predominant frequencies (lengthening of the period), particularly in the alluvial basin, has been observed with higher input PGAROCK in the EQL analysis. This effect is not manifested in the Trakoscan hill, and predominant frequencies match HVSR frequencies. The use of certain geophysical survey methods at historical sites is a big problem, because terrain features (e.g. steep hills, mountains, ridges, slopes, cliffs) create lack of space and make it impossible to carry out geophysical investigation. Microtremor measurements at historical sites can overcome this limitation and provide local seismic response and vulnerability behaviour of historical monuments without destroying their authenticity. Also, computational modelling can greatly improve the results. The EQL site response analysis on the site of Trakoscan Castle has confirmed and improved the results of seismic response and vulnerability based on HVSR method.

Research progress of geophysical vector magnetic field survey technology

Vector magnetic survey technique is one of the most effective methods for engineering and environmental geophysical exploration. Compared with the traditional geophysical magnetic survey methods, i.e., measurement of the total magnetic field intensity or its gradient, vector magnetic survey can simultaneously obtain the modulus and direction information of the earth magnetic field, which can effectively reduce the multiplicity on data inversion, contribute to the quantitative interpretation of the magnetic body and obtain more precise information and characteristics of magnetic field resource, so as to improve the detection resolution and positioning accuracy of the underground target body. In this paper, based on different application fields, we summarize the application situation, the technical feature and the instrument development of ground vector magnetic survey technique, wells vector magnetic survey technique, marine vector magnetic survey technique, airborne vector magnetic survey technique and satellites vector magnetic survey technique, respectively. As the basic method of the vector magnetic survey technique, ground vector magnetic survey development is the earliest and the technique is the most mature. The accuracy of the instrument system for ground vector magnetic survey is high and the working performance is reliable. But there are also some problems, e.g., the detection depth is shallow and working efficiency is low. Wells vector magnetic survey is one useful tool for the earth’s deep mineral resources exploration. It can finish the detection work that the ground vector magnetic measurement can’t do. But due to the limit of the bore diameter and the high temperature in well, the detection accuracy of the instrument system is lower than the ground magnetic instrument. Marine vector magnetic survey has the irreplaceable effect in the application of military or other ocean engineering. Its working mode changes from the method of ship drag-and-drop to small unmanned underwater vehicle, which can measure more precise underwater magnetic anomaly. Airborne vector magnetic survey has the superiority of fast detection, high efficiency and strong practicality to geophysical environment, etc. But because of magnetic interference and the posture change of the aircraft carrier, detection accuracy reduces. The study of magnetic compensation and data processing methods of aero three-component and full-tensor magnetic gradient is also needed. Satellites vector magnetic survey can obtain high-quality and whole global magnetic field data. Compared with the research abroad, the development of satellites vector magnetic survey in China is later and the technique is relatively backward although lots of exploration work has been done in recent years. We should take full advantage of the opportunity of China aerospace business development to actively carry out research work for the satellites vector magnetic survey. In conclusion, each magnetic survey method has its unique superiority and defect. Any single method has difficulty meeting the requirement of modern geophysical detection application. With the development of magnetic survey technique and instrument system, the future magnetic survey will change from the traditional work mode, i . e ., measuring the total magnetic field intensity or its gradient to the vector information of magnetic field, then to multi-parameter measurements. The magnetic survey application field will change from the traditional ground magnetic survey method with low efficiency and shallow detection depth to high efficient airborne magnetic survey, deep well magnetic survey and abysmal sea magnetic survey, then gradually to the joint detection and interpretation combining with the five kinds of magnetic survey methods mentioned above. Through the combination of a variety of detection methods to realize advantageous complementarities, further improvement of detection accuracy and inversion resolution for earth magnetic field will be implemented.

Resistivity and induced polarization to support morphological modeling in limestone mining

This paper presents the results of the application of geophysical surveys to update the morphological model of a limestone and gneiss deposit of a mining company near the city of Taubaté, Brazil. The research began with a test to verify the accuracy of the geophysical survey method and it was conducted in the same area as a previous drilling campaign with the aim of confirming the possibility of using Vertical Electrical Sounding (VES) and induced polarization (IP) methods, in order to obtain the required information for the deposit morphological modeling. As a result, the application of geophysical methods in the study area reduced up to 75% the data collection time and presented similar accuracy levels as conventional exploration methods used for the same research objectives.