scholarly journals First geophysical results in the Archeological sites of Θούρια (Péloponnèse, Hellas) and Sibari-Thurii (southern Italy)

2018 ◽  
Vol 40 (3) ◽  
pp. 1080
Author(s):  
B. Di Fiore ◽  
D. Chianese ◽  
A. Loperte ◽  
G. Conte ◽  
A. Dibenedetto ◽  
...  
Keyword(s):  
High Resolution ◽  
Information Quality ◽  
Southern Italy ◽  
Magnetic Measurements ◽  
Early Stage ◽  
Geophysical Methods ◽  
Magnetic Data ◽  
Near Surface ◽  
Data Inversion ◽  
Near Surface Geophysics

High resolution techniques for data acquisition and processing procedures are increasingly applied in near-surface geophysics for archaeology. In this paper we present the preliminary results of two geophysical measurements campaigns aimed to the investigation of buried remains in the archaeological sites of Θουρία (Péloponnèse, Hellas) and Sibari (Southern Italy). In the first field survey the geophysical approach involved the integrated application of the geoelectrical and magnetic methods and an innovative tomographic analysis for the inversion of both resistivity and magnetic data. In the second case, we carried out high resolution magnetic measurements, interpreted by means of the use of an appropriate filtering procedure. The applied data inversion allows us to provide reliable space patterns of the most probable specific target boundaries, improving the information quality of geophysical methods. The results obtained at this early stage of data processing confirm some archaeological hypothesis about the investigated areas and confirm that the use of integrated geophysical methods allows the archaeologists to reduce the time and the costs of their surveys.

scholarly journals APPLICATION OF UNMANNED AERIAL VEHICLE AS A BASE MAP LAYER IN NEAR-SURFACE GEOPHYSICS

2021 ◽  
Vol 13 (1) ◽  
pp. 26
Author(s):  
Muhammad Yanis ◽  
Aprilla Hasibuan Anggini ◽  
Faisal Abdullah ◽  
Muzakir Zainal ◽  
Marwan Abubakar
Keyword(s):  
Data Analysis ◽  
High Resolution ◽  
Good Condition ◽  
Data Interpretation ◽  
Research Area ◽  
Magnetic Data ◽  
Physical Parameters ◽  
Large Area ◽  
Near Surface ◽  
Near Surface Geophysics

The Geophysical method is operated by using physical parameters above the surface to estimate the subsurface structures. In data interpretation, all 3D surveys, i.e., magnetic, gravity, magnetotelluric, and airborne, are required for geographical conditions in the research area. In a large area, global DEM data is used to explain the field condition, but for local measurement, the data is not efficient due to low resolution (15-30 m/px). This research uses UAV technology to produce a high-resolution topography in local Geophysical measurement (500 x 600 m). The survey was conducted to map the coal structure in the subsurface. UAV data were also compared to SRTM (30 m/px) and DEMNAS (8 m/px) as global topography. Based on data processing, the UAV topographic was have a high resolution of 2.5 cm/px. Comparison of UAV and magnetic data are able to explain a good condition of field measurement than a global DEM data, even in a relatively small area; outcrops of the coal (50x50 m) can show a good differences contrast of topography. Based on data analysis, we can conclude that UAV technology can interpret the geophysical data measured in a local area.Keywords: UAV, SRTM, Topography, Geophysical Interpretation.Metode Geofisika bekerja dengan memanfaatkan parameter fisis diatas permukaan untuk pendugaan struktur bawah permukaan. Dalam tahapan interpretasi data, semua pengukuran 3D Geofisika; magnetic, gravity, magnetotelluric, dan airbone sangat membutuhkan keadaan geografis lapangan. Pada area yang luas, data DEM global digunakan untuk menjelaskan deskripsi lapangan, namun untuk pengukuran dekat permukaan yang bersifat lokal, data ini tidaklah efesien, karena resolusi yang relative rendah (15 – 30 m/px). Kami menggunakan teknologi UAV untuk menghasilkan topografi resolusi tinggi pada area pengukuran Geofisika dengan luas 500 x 600 m, yang disurvei untuk pemetaan batubara dibawah permukaan. Data UAV juga dibandingkan dengan topografi global SRTM (30 m/px) dan DEMNAS (8 m/px). Hasil pengolahan data menunjukkan data UAV menghasilkan topografi dengan resolusi 2.5 cm/px. Hasil overlay UAV dengan Geofisika magnetik mampu menjelaskan deskripsi lapangan dengan sangat baik dibandingkan DEM global, bahkan pada area yang relative kecil seperti singkapan batuabara (50x50 m) dapat menunjukkan keadaan perbedaan topografi dengan kontras. Berdasarkan data analysis, topografi UAV sangat potensial digunakan untuk interpretasi data Geofisika dekat permukaan yang diukur pada area yang relative lokal.Kata kunci: UAV, SRTM, Topografi, Interpretasi Geofisika.

scholarly journals Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling

Solid Earth ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 1685-1705
Author(s):  
Silvia Salas-Romero ◽  
Alireza Malehmir ◽  
Ian Snowball ◽  
Benoît Dessirier
Keyword(s):  
Large Scale ◽  
Geophysical Methods ◽  
Hydrological Modelling ◽  
P Wave ◽  
Coarse Grained ◽  
Near Surface ◽  
Reflection Seismic ◽  
Geotechnical Investigations ◽  
Quick Clay ◽  
Near Surface Geophysics

Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.

scholarly journals Subsurface structures of a quick-clay sliding prone area revealed using land-river reflection seismic data and hydrogeological modelling

2019 ◽  
Author(s):  
Silvia Salas-Romero ◽  
Alireza Malehmir ◽  
Ian Snowball ◽  
Benoît Dessirier
Keyword(s):  
Large Scale ◽  
Geophysical Methods ◽  
Coarse Grained ◽  
Magnetic Data ◽  
Near Surface ◽  
Side Scan Sonar ◽  
Reflection Seismic ◽  
Subsurface Structures ◽  
Geotechnical Investigations ◽  
Quick Clay

Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identifying coarse-grained materials associated to the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with the radio magnetotelluric and traveltime tomography models. The morphology of the river bottom and riverbanks, as e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits is clearly revealed. An extensive coarse-grained layer exists in the sedimentary sequence and is interpreted and modelled in a regional context. Individual fractures and fracture zones are identified within bedrock and sediments. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops. The groundwater flow in the coarse-grained layer promotes leaching of marine salts from the overlying clays by slow infiltration and/or diffusion, which helps in the formation of potential quick clays. Magnetic data show coarse-grained materials at the landslide scar located in the study area, which may have acted as a sliding surface together with quick clays.

Ultra-lightweight integrated unmanned aerial systems for a wide range of geophysical magnetic exploration: a single system for high-precision archaeological surveys to rugged topography geological acquisitions

2021 ◽  
Author(s):  
Jeanne Mercier de Lépinay ◽  
Tristan Fréville ◽  
Baptiste Kiemes ◽  
Luis Miguel Sanabria ◽  
Bruno Gavazzi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
High Precision ◽  
Adaptive Systems ◽  
Magnetic Measurements ◽  
Magnetic Sensor ◽  
Magnetic Data ◽  
Industrial Sectors ◽  
Wide Range ◽  
The Magnetic Field

<p>Magnetic mapping is commonly used in the academic and industrial sectors for a wide variety of objectives. To comply with a broad range of survey designs, the use of unmanned aerial vehicles (UAVs) has become frequent over the recent years. The majority of existing systems involves a magnetic acquisition equipment and its carrier (an UAV in this context) with no -or very few- connections between the two systems. Terremys is conceiving and optimizing UAVs specifically adapted for geophysical magnetic acquisitions together with the appropriate processing tools, and performs magnetic surveying in challenging environments. Terremys’ “Q6” system weights 2.5 kg in air, including UAV & instrumentation, and allows 30 min swarm or individual flights.</p><p>Rotary-wing UAVs are found to be the most adaptive systems for a wide range of contexts and constraints (extensive range of flights heights even with steep slopes). They offer more flight flexibility than fixed-wing aircrafts. One of the major problems in the use of rotary-wings UAVs for magnetic mapping is the magnetic field generated by the aircraft itself on the measurements. Towing the magnetic sensor 2 to 5 m under the aircraft reduces data positioning accuracy and decreases the performances of the UAV, which can be critical for high-resolution surveys. To overcome these problems, a deployable 1 m long boom is rigidly attached to the UAV. The UAV magnetic signal can be divided between 1-the magnetic field of the whole equipment and 2-a low to high frequency magnetic field mostly originating from the motors. The magnetization of the system is the principal source of magnetic noise. It is modelled and corrected by calibration-compensation processes permitted by the use of three-component fluxgate magnetometers. The time-varying noise depends on the motors rotational speed and is minimized by optimizing the UAV components and characteristics along with the boom’s length.</p><p>The final set-up is able to acquire magnetic data with a precision of 1 to 5 nT at any height from 1 to 150 m above ground level. The high-precision magnetic measurements are coupled with a centimetric RTK navigation system to allow for high-resolution surveying. The quality of the obtained data is similar to that obtained with ground or aerial surveys with conventional carriers and matches industrial standards. Moreover, Terremys’ systems merge in real-time data from all the aircraft instruments in order to integrate magnetic measurements, positioning information and all the UAV’s flight data (full telemetry) into a unique synchronized data file. This opens up many possibilities in terms of QA/QC, data processing and facilitates on-field workflows.</p><p>Case studies with diverse designs, flight altitudes and targets are presented to investigate the acquisition performances for different applications, as distinct as network positioning, archaeological prospecting or geological mapping.</p><p>The full integration of the magnetic sensor to the drone opens the possibility for implementation additional sensors to the system. The adjoining of other magnetic sensors would allow multi-sensors surveying and increases daily productivity. Diverse geophysical sensors can also be added, such as thermal/infrared cameras, spectrometers, radar/SAR.</p>

Multi-length TDR probes: future perspectives

2021 ◽  
Author(s):  
Raffaele Persico ◽  
Lourdes Farrugia ◽  
Iman Farhat ◽  
Charles Sammut
Keyword(s):  
Magnetic Properties ◽  
Early Stage ◽  
Coaxial Cable ◽  
Magnetic Characteristics ◽  
Future Perspectives ◽  
Near Surface ◽  
Work Related ◽  
Properties Of Materials ◽  
Near Surface Geophysics ◽  
Engineering Geophysics

<p>In this contribution we will propose the use of multi-length TDR probes for measurements of the dielectric and possibly magnetic characteristics of a material under test (MUT) as a function of frequency. The multi-length strategy, consisting in making use of a TDR probe with adjustable length of the conductors, can allow the meaningful increase of information achievable about the MUT at each test frequency. We are still at an early stage about these possibilities, and many questions are still open at this time. However, some of our previous studies [1-3] show that the method is promising and can permit the acquisition of some information not intrinsically available from a traditional TDR probe, especially if the MUT shows a dispersive behaviour and possibly magnetic properties. In this contribution, we will discuss the recent work related in particular to geophysical applications.</p><p><strong>Acknowledgements</strong></p><p>This work in progress is being carried out within the European Cost Action CA17115 Mywave.</p><p><strong>References</strong></p><p>[1] R. Persico, M. Pieraccini, Measurement of dielectric and magnetic properties of Materials by means of a TDR probe, Near Surface Geophysics, vol. 16, n.2, pp.1-9, DOI:10.3997/1873-0604.2017046, 2018.</p><p>[2] R. Persico, I. Farhat, L. Farrugia, S. d’Amico, C. Sammut, An innovative use of TDR probes: First numerical validations with a coaxial cable, Journal of Environmental & Engineering Geophysics, doi.org/10.2113/JEEG23.4.437, 23 (4): 437-442, 2018.</p><p>[3] I. Farhat, L. Farrugia, R. Persico, S. D’Amico, and C. Sammut, Preliminary Experimental Measurements of the Dielectric and Magnetic Properties of a Material with a Coaxial TDR Probe in Reflection Mode, Progress In Electromagnetics Research M, Vol. 91, 111–121, 2020.</p>

Characterization of heterogeneous landfill: seismic waveform inversion and wavefield retrieval to integrated quantitative inversion of high-resolution seismic-electrical datasets

2020 ◽  
Author(s):  
Ranajit Ghose
Keyword(s):  
High Resolution ◽  
Preferential Flow ◽  
Waveform Inversion ◽  
Geophysical Methods ◽  
Matric Suction ◽  
Phreatic Surface ◽  
Near Surface ◽  
Degradation Processes ◽  
Seismic Waveform ◽  
Seismic Wavefield

<p>A landfill body is typically highly heterogeneous. The scale of these heterogeneities - which are relevant for the purpose of assessment of preferential flow paths, the degradation processes, and the spatio-temporally varying aging and settlements - is quite often small considering the limiting resolution and confidence of the prevalent near-surface geophysical methods. High-density areas act as obstruction to fluid flow and are important for understanding the degradation processes. These areas manifest as scatterers in the recorded seismic wavefield. Strong presence of scattered energy is typical of seismic datasets acquired on landfills. Our research has been concentrated on resolving and monitoring density and porosity variations, as well as distribution of water saturation, phreatic surface, matric suction and stress. Dedicated schemes of early-arrival waveform tomography, full-waveform inversion and interferometric seismic wavefield retrieval complemented by electrical resistivity tomography show promise in high-resolution delineation and monitoring of these properties in a heterogeneous landfill. We will discuss the results of a novel inversion scheme which allows quantitative estimation of spatio-temporally heterogeneous matric suction, stress and porosity.</p>

scholarly journals Interpretation of high resolution airborne magnetic data (HRAMD) of Ilesha and its environs, Southwest Nigeria, using Euler deconvolution method

2017 ◽  
Vol 64 (4) ◽  
pp. 227-241
Author(s):  
Oluwaseun Tolutope Olurin
Keyword(s):  
High Resolution ◽  
High Amplitude ◽  
Sharp Contrast ◽  
Magnetic Data ◽  
Magnetic Intensity ◽  
Euler Deconvolution ◽  
Southwestern Nigeria ◽  
Near Surface ◽  
Low Amplitude ◽  
Airborne Magnetic

AbstractInterpretation of high resolution aeromagnetic data of Ilesha and its environs within the basement complex of the geological setting of Southwestern Nigeria was carried out in the study. The study area is delimited by geographic latitudes 7°30′–8°00′N and longitudes 4°30′–5°00′E. This investigation was carried out using Euler deconvolution on filtered digitised total magnetic data (Sheet Number 243) to delineate geological structures within the area under consideration. The digitised airborne magnetic data acquired in 2009 were obtained from the archives of the Nigeria Geological Survey Agency (NGSA). The airborne magnetic data were filtered, processed and enhanced; the resultant data were subjected to qualitative and quantitative magnetic interpretation, geometry and depth weighting analyses across the study area using Euler deconvolution filter control file in Oasis Montag software. Total magnetic intensity distribution in the field ranged from –77.7 to 139.7 nT. Total magnetic field intensities reveal high-magnitude magnetic intensity values (high-amplitude anomaly) and magnetic low intensities (low-amplitude magnetic anomaly) in the area under consideration. The study area is characterised with high intensity correlated with lithological variation in the basement. The sharp contrast is enhanced due to the sharp contrast in magnetic intensity between the magnetic susceptibilities of the crystalline and sedimentary rocks. The reduced-to-equator (RTE) map is characterised by high frequencies, short wavelengths, small size, weak intensity, sharp low amplitude and nearly irregular shaped anomalies, which may due to near-surface sources, such as shallow geologic units and cultural features. Euler deconvolution solution indicates a generally undulating basement, with a depth ranging from −500 to 1000 m. The Euler deconvolution results show that the basement relief is generally gentle and flat, lying within the basement terrain.

Introduction to this special section: Near-surface geophysics

2019 ◽  
Vol 38 (6) ◽  
pp. 434-434
Author(s):  
Adam Mangel ◽  
Steve Sloan
Keyword(s):  
Special Section ◽  
Geophysical Methods ◽  
National Research Council ◽  
Natural World ◽  
Food Sources ◽  
Natural Ecosystems ◽  
Near Surface ◽  
The Past ◽  
The Earth ◽  
Near Surface Geophysics

The near surface of the earth, a.k.a. the critical zone (National Research Council, 2001), is defined as the outer 50–100 m of the planet, which contains biota, bedrock, soil, water, and gasses. As humans, we rely on this layer for many functions including storage of water resources, housing of our infrastructure, storage of our wastes, and cultivation of our food sources. Several natural ecosystems are also dependent on this layer of our planet, which in turn provide us with ecosystem services. The historic and lasting importance of this layer to our environment emphasizes the value in understanding major environmental fluxes, impact of human activities, and the interface between the natural world and our infrastructure. Application of geophysical methods in this field has increased steadily over the past 15 years and continues to grow, especially as the human impact on the globe continues to increase.

scholarly journals Joint inversion of EM and magnetic data for near‐surface studies

Geophysics ◽  
2002 ◽  
Vol 67 (6) ◽  
pp. 1729-1739 ◽  
Author(s):  
Christophe Benech ◽  
Alain Tabbagh ◽  
Guy Desvignes
Keyword(s):  
Magnetic Susceptibility ◽  
Case Studies ◽  
Joint Inversion ◽  
Synthetic Data ◽  
Magnetic Data ◽  
Near Surface ◽  
Data Inversion ◽  
Electromagnetic Measurements ◽  
Geophysical Surveys ◽  
Depth Analysis

Magnetic and electromagnetic measurements are influenced by magnetic susceptibility and, thus, are widely used in geophysical surveys for archeology or pedology. To date, the data inversion is performed separately. A filtering process incorporating both types of data is presented here. After testing the algorithm with synthetic data, the algorithm is used in several case studies in archeological prospecting. This approach presents two advantages: establishing the presence of remanent magnetizations (viscous or thermoremanent), and achieving more refined depth analysis of the anomaly.

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