A multi-scale ground and drone-borne magnetic survey approach for the detection and investigation of archaeological structures

2021 ◽  
Author(s):  
Bruno Gavazzi ◽  
Hugo Reiller ◽  
Marc Munschy ◽  
Gilles Pierrevelcin ◽  
Florian Basoge ◽  
...  
Keyword(s):  
Vertical Component ◽  
High Amplitude ◽  
Magnetic Survey ◽  
Rhine River ◽  
Near Surface ◽  
Multi Scale ◽  
Electric Power Line ◽  
Frequency Magnetic Field ◽  
Ground Magnetic

<p><span>Ground magnetic surveys are commonly used for imaging near-surface structures in archaeological studies. Usually, surveys are conducted using vertical component gradiometers or scalar gradiometers to produce a vertical pseudo-gradient map. Scalar magnetometers can also be used, albeit less frequently, to produce maps of the total magnetic anomaly. In all these cases, the equipment is pushed or pulled by an operator or carried behind a vehicle. Here we present a third approach made available by the use of three-component fluxgate magnetometers: fast surveys over large areas using a compact lightweight drone flying automatically 1 to 2 m above the ground and high precision surveys acquired by an operator 0,2 to 1 m above the ground. A case study on the gallo-roman site of Oedenburg, </span><span>located</span><span> along the Rhine River in its upper valley, illustrates the results that can be obtained with the approach. A comparison with previously acquired pseudo-gradient surveys show</span><span>s</span><span> that the presented method allows a faster coverage, a greater resolution for the imaging of short wavelength structures (such as walls) and a better capacity of imaging large wavelength structures (such as pathways, palaeochannels or soil composition variations). As the site is crossed by a high voltage electric power line, a method to suppress the high-amplitude 50 Hz frequency magnetic field is presented.</span></p>

scholarly journals Real magnetic stripping method in unexploded ordnance detection and remediation – a case study from Rohožník military training range in SW Slovakia

2021 ◽  
Vol 51 (3) ◽  
pp. 277-294
Author(s):  
Roman PAŠTEKA ◽  
Miroslav HAJACH ◽  
Bibiana BRIXOVÁ ◽  
Ján MIKUŠKA ◽  
John STANLEY
Keyword(s):  
Military Training ◽  
High Amplitude ◽  
Magnetic Data ◽  
Unexploded Ordnance ◽  
High Definition ◽  
Near Surface ◽  
3D Euler Deconvolution ◽  
Explosive Ordnance Disposal ◽  
Deep Source

In this contribution we present results from a case-study, which was performed in collaboration between geophysicists and explosive ordnance disposal technicians at the Rohožník military training range in SW Slovakia. The aim of this study was to locate a deep-penetrated unexploded Mk-82 aerial bomb using high-definition digital magnetometry. The location where this bomb had entered the ground was known but its final position needed to be determined so that a safe excavation and disposal could be conducted. However, the detection of this unexploded ordnance object was complicated by the presence of intense magnetic interference from a number of near surface ferrous items including non-explosive test bombs, fragmentation and other iron junk. These items contributed a localised, high amplitude of magnetic clutter masking any deeper source. Our strategy was to approach the problem in three stages. First, we used magnetic data to locate the near surface items. After the detection and before the excavation of the searched objects, two quantitative interpretation methods were used. These involved an optimised modelling of source bodies and the application of a 3D Euler deconvolution. Both methods yielded acceptable results, but the former was found to be more accurate. After the interpretation phase, many of the items were then safely excavated and removed individually. A second magnetic mapping was then performed and from this data which was now significantly less cluttered, we were able to identify but not quantify, two deep source items and to confirm that all remaining near surface items were significantly smaller in size than a Mk-82 bomb. As the remaining near surface sources were interpreted as being contained within the surface one metre of soil and being small they could be assured to be non-explosive, it was considered most practical to mechanically excavate and remove this soil and the remaining objects contained.

Delineating hydrothermal stockwork copper deposits using controlled-source and radio-magnetotelluric methods: A case study from northeast Iran

Geophysics ◽  
2009 ◽  
Vol 74 (5) ◽  
pp. B167-B181 ◽  
Author(s):  
Mehrdad Bastani ◽  
Alireza Malehmir ◽  
Nazli Ismail ◽  
Laust B. Pedersen ◽  
Farhang Hedjazi
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Near Surface ◽  
2D Inversion ◽  
Controlled Source ◽  
Copper Mineralization ◽  
Radio Transmitters ◽  
Ground Magnetic ◽  
2D Resistivity

Radio- and controlled-source-tensor magnetotelluric (RMT and CSTMT) methods are used to target hydrothermal veins of copper mineralization. The data were acquired along six east-west- and three north-south-trending profiles, covering an area of about [Formula: see text]. The tensor RMT data were collected in the [Formula: see text] frequency band. A double horizontal magnetic dipole transmitter in the [Formula: see text] frequency range allowed us to constrain the deeper parts of the resistivity models better. To obtain optimum field parameters, ground magnetic profiling was conducted prior to the RMT and CSTMT surveys. Although the study area (in Iran) is remote, a number of radio transmitters with acceptable signal-to-noise ratio were utilized. The 2D inversion of RMT data led to unstable resistivity models with large datamisfits. Thus, the RMT data were used to complement and analyze the near-surface resistivity anomalies observed in the 2D CSTMT models. Analyses of strike and dimensionality from the CSTMT data suggests that the low-resistivity structures are mainly three dimensional; therefore, 2D inversion of determinant data is chosen. Independent 2D inversion models of the determinant CSTMT data along crossing profiles are in good agreement. Known copper mineralization is imaged well in the CSTMT models. The thinning of the conductive overburden correlates very well with magnetic highs, indicating the bedrock is resistive and magnetic. In this sense, the magnetic and electromagnetic fields complement each other. Analysis of the 2D resistivity models indicates the volcanic rock deepens at the center of the study area. This zone is associated with a magnetic low and therefore is recommended for detailed exploration work.

Epigenetic versus syngenetic magnetite as a cause of magnetic anomalies

Geophysics ◽  
1992 ◽  
Vol 57 (1) ◽  
pp. 60-68 ◽  
Author(s):  
S. Parker Gay
Keyword(s):  
Magnetic Susceptibility ◽  
High Frequency ◽  
Magnetic Anomalies ◽  
High Amplitude ◽  
Sulfide Mineral ◽  
Unconsolidated Sediments ◽  
Near Surface ◽  
Surface Magnetization ◽  
Ground Magnetic ◽  
Low Amplitude

Studies carried out a decade ago at Cement Field, Oklahoma, suggesting evidence of epigenetic (diagenetic) magnetite are shown to have been flawed for two reasons. Aeromagnetic surveying over the field could not have yielded the type of broad, low‐amplitude anomalies expected from hypothesized diagenetic magnetite sources because of the occurrence of numerous high‐amplitude magnetic spikes over cultural sources. Applied Geophysics, Inc., flew a low level (approximately 30 m above ground) aeromagnetic profile along the long axis of the field in 1983 and encountered nearly 40 such spikes due to culture. Additionally, studies of drill cuttings from 23 wells in the field showed them all to be contaminated by rust, scale, and bit shavings, in approximately the same percentages as had been postulated for diagenetic magnetite in 5 wells examined in the prior study. Subsequent studies in support of the diagenetic magnetite hypothesis in other areas have relied on the occurrence of “high‐wavenumber” (i.e., high‐frequency) aeromagnetic or ground magnetic anomalies as indicators of such magnetite. These studies do not take into account the possibility of detrital magnetite as the cause of the high‐frequency anomalies. Detrital magnetite is of near‐universal occurrence in small quantities in both unconsolidated sediments and sedimentary rocks and is easily concentrated by fluvial processes which would affect ground magnetic surveys in particular, but airborne surveys as well. In rocks of Mesozoic age or younger, detrital magnetite occurs in sufficient quantity in some areas to give quite detectable airborne magnetic anomalies. Four such localities have recently been documented, one in the Utah‐Idaho‐Wyoming USA thrust belt; and two in the western United States and one in Central America. However, recent measurements of soil magnetic susceptibility over oil fields do present intriguing evidence for anomalous near‐surface magnetization associated with hydrocarbon leakage plumes. Based on previous experience with sulfide mineral deposits, I postulate that small quantities of pyrite, and perhaps lesser quantities of other sulfide minerals that are sometimes precipitated by rising hydrocarbons, are oxidized above the water table in the vadose zone to secondary magnetic iron oxides. This thin layer of weak anomalous magnetization, when properly distinguished from magnetization due to detrital magnetite, would be recognizable with shallow magnetic susceptibility measurements, and possibly ground magnetic surveys, but probably not with airborne surveys, except under exceptional circumstances.

scholarly journals Land Magnetic survey along a profile from Akaz to Rutba town and its applications

2012 ◽  
Vol 9 (1) ◽  
pp. 63-71
Author(s):  
Baghdad Science Journal
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Measurements ◽  
Continuation Method ◽  
Vertical Component ◽  
Base Station ◽  
Western Desert ◽  
Magnetic Survey ◽  
Fracture Density ◽  
Geological Time ◽  
Near Surface

A land magnetic survey was carried out along regional profile, which is located at the north part of the Iraqi western desert. It starts from al –Qaam City (at north) toward Rutba City (at south) with a total length of 238km. The survey was carried out along the paved road between the two cities, About 113 measuring points were done with inter-station distance of 2 km (for 198 km) and 2 to 5km (for 40km). Two proton magnetometers were used in this survey. One of them is used for base station monitoring, which was fixed as of Salah Aldin field (Akkas). Its readings were used for diurnal corrections. All magnetic measurements were corrected for normal and topographic corrections. The readings were reduced to a certain base level. The resulted magnetic anomalies show a good correlation with those of Arial - magnetic survey anomalies conducted by (C.G.G, 1974). This is true for those anomalies with wavelength more than 50km. While the land magnetic survey has shown more small anomalies which may reflect near surface sources. In addition, there is a considerable difference between the magnetic intensity values of both surveys. The downward continuation method was used in this study for detecting the depth of magnetic anomaly source. But before applying this method the total magnetic field was converted to its vertical component using computer program packages. The 2.5 mathematical modeling techniques were used for interpreting magnetic anomaly. Several models were suggested according to the geological and geophysical surface and subsurface data. These models clearly suggest that the tectonic of the studied area may be completely affected by deep faults that could reach the basements or even cut it. These faults resulted in tectonic blocks with relative movements that could happen through the geological time, and they may be responsible for the tectonic features of the western desert. These faults could also responsible for the lateral and vertical variations that are noticed in subsurface rocks of the studied area. The subsurface lateral susceptibility variation between the different blocks could result from the variation in physical parameter of the rocks (like porosity, fracture density…) and there is a possibility that rocks beneath 18km (lower crust) still possess some magnetic properties.

A LOOK INTO THE EARTH: EVALUATING THE USE OF MAGNETIC SURVEY IN AFRICAN ARCHAEOLOGY

2004 ◽  
Vol 2 (1) ◽  
pp. 49-63 ◽  
Author(s):  
Carlos Magnavita ◽  
Norbert Schleifer
Keyword(s):  
Geophysical Methods ◽  
Field Research ◽  
Archaeological Sites ◽  
Magnetic Survey ◽  
The Past ◽  
Common Technique ◽  
Sub Saharan ◽  
Prehistoric Settlements ◽  
Present Case Study

In the last decades, geophysical methods such as magnetic survey have become a common technique for prospecting archaeological sites. At sub-Saharan archaeological sites, however, magnetic survey and correlated techniques never came into broad use and there are no signs for an immediate change of this situation. This paper examines the magnetic survey undertaken on the Nigerian site of Zilum, a settlement of the Gajiganna Culture (ca 1800-400 BC) located in the Chad Basin and dated to ca 600-400 BC. By means of the present case study, we demonstrate the significance of this particular type of investigation in yielding complementary data for understanding the character of prehistoric settlements. In conclusion, we point out that geophysical methods should play a more important role in modern archaeological field research, as they furnish a class of documentation not achievable by traditional survey and excavation methods, thus creating new perspectives for interpreting the past of African societies.

scholarly journals Improved Process Monitoring Scheme Using Multi-Scale Independent Component Analysis

2021 ◽  
Author(s):  
K Ramakrishna Kini ◽  
Muddu Madakyaru
Keyword(s):  
Fault Detection ◽  
Independent Component Analysis ◽  
Component Analysis ◽  
Independent Component ◽  
Noisy Environment ◽  
Process Data ◽  
Multi Scale ◽  
Efficient Information ◽  
Non Gaussian

AbstractThe task of fault detection is crucial in modern chemical industries for improved product quality and process safety. In this regard, data-driven fault detection (FD) strategy based on independent component analysis (ICA) has gained attention since it improves monitoring by capturing non-gaussian features in the process data. However, presence of measurement noise in the process data degrades performance of the FD strategy since the noise masks important information. To enhance the monitoring under noisy environment, wavelet-based multi-scale filtering is integrated with the ICA model to yield a novel multi-scale Independent component analysis (MSICA) FD strategy. One of the challenges in multi-scale ICA modeling is to choose the optimum decomposition depth. A novel scheme based on ICA model parameter estimation at each depth is proposed in this paper to achieve this. The effectiveness of the proposed MSICA-based FD strategy is illustrated through three case studies, namely: dynamic multi-variate process, quadruple tank process and distillation column process. In each case study, the performance of the MSICA FD strategy is assessed for different noise levels by comparing it with the conventional FD strategies. The results indicate that the proposed MSICA FD strategy can enhance performance for higher levels of noise in the data since multi-scale wavelet-based filtering is able to de-noise and capture efficient information from noisy process data.

Multi-scale flooding hazards evaluation using a nested flood simulation model: Case study of Jamuna River, Bangladesh

2021 ◽  
pp. 1-38
Author(s):  
Masakazu Hashimoto ◽  
Kenji Kawaike ◽  
Tomonori Deguchi ◽  
Shammi Haque ◽  
Arpan Paul ◽  
...  
Keyword(s):  
Simulation Model ◽  
Model Case ◽  
Flood Simulation ◽  
Multi Scale ◽  
Flooding Hazards

A hydrochemical and isotopic case study around a near surface radioactive waste disposal

2007 ◽  
Vol 95 (1) ◽  
Author(s):  
Zs. Szántó ◽  
É. Svingor ◽  
I. Futó ◽  
L. Palcsu ◽  
M. Molnár ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Waste Treatment ◽  
Radioactive Waste Disposal ◽  
Ion Chemistry ◽  
Continuous Transition ◽  
Near Surface ◽  
Disposal Facility ◽  
Treatment And Disposal ◽  
Site Characterisation

As part of the site characterisation program for the near surface radioactive waste treatment and disposal facility (RWTDF) at Püspökszilágy, Hungary, water quality and environmental isotope investigations have been carried out. Water samples for major ion chemistry, tritium,The chemical composition of groundwaters presented a continuous transition from waters situated on one side to waters on the top and on the other slope of the disposal suggesting the mixing of the three hydrochemical “endmembers”.Most of δ

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